File: | build/source/llvm/lib/Analysis/ValueTracking.cpp |
Warning: | line 5641, column 22 Called C++ object pointer is null |
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1 | //===- ValueTracking.cpp - Walk computations to compute properties --------===// | |||
2 | // | |||
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | |||
4 | // See https://llvm.org/LICENSE.txt for license information. | |||
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | |||
6 | // | |||
7 | //===----------------------------------------------------------------------===// | |||
8 | // | |||
9 | // This file contains routines that help analyze properties that chains of | |||
10 | // computations have. | |||
11 | // | |||
12 | //===----------------------------------------------------------------------===// | |||
13 | ||||
14 | #include "llvm/Analysis/ValueTracking.h" | |||
15 | #include "llvm/ADT/APFloat.h" | |||
16 | #include "llvm/ADT/APInt.h" | |||
17 | #include "llvm/ADT/ArrayRef.h" | |||
18 | #include "llvm/ADT/STLExtras.h" | |||
19 | #include "llvm/ADT/ScopeExit.h" | |||
20 | #include "llvm/ADT/SmallPtrSet.h" | |||
21 | #include "llvm/ADT/SmallSet.h" | |||
22 | #include "llvm/ADT/SmallVector.h" | |||
23 | #include "llvm/ADT/StringRef.h" | |||
24 | #include "llvm/ADT/iterator_range.h" | |||
25 | #include "llvm/Analysis/AliasAnalysis.h" | |||
26 | #include "llvm/Analysis/AssumeBundleQueries.h" | |||
27 | #include "llvm/Analysis/AssumptionCache.h" | |||
28 | #include "llvm/Analysis/ConstantFolding.h" | |||
29 | #include "llvm/Analysis/GuardUtils.h" | |||
30 | #include "llvm/Analysis/InstructionSimplify.h" | |||
31 | #include "llvm/Analysis/Loads.h" | |||
32 | #include "llvm/Analysis/LoopInfo.h" | |||
33 | #include "llvm/Analysis/OptimizationRemarkEmitter.h" | |||
34 | #include "llvm/Analysis/TargetLibraryInfo.h" | |||
35 | #include "llvm/Analysis/VectorUtils.h" | |||
36 | #include "llvm/IR/Argument.h" | |||
37 | #include "llvm/IR/Attributes.h" | |||
38 | #include "llvm/IR/BasicBlock.h" | |||
39 | #include "llvm/IR/Constant.h" | |||
40 | #include "llvm/IR/ConstantRange.h" | |||
41 | #include "llvm/IR/Constants.h" | |||
42 | #include "llvm/IR/DerivedTypes.h" | |||
43 | #include "llvm/IR/DiagnosticInfo.h" | |||
44 | #include "llvm/IR/Dominators.h" | |||
45 | #include "llvm/IR/EHPersonalities.h" | |||
46 | #include "llvm/IR/Function.h" | |||
47 | #include "llvm/IR/GetElementPtrTypeIterator.h" | |||
48 | #include "llvm/IR/GlobalAlias.h" | |||
49 | #include "llvm/IR/GlobalValue.h" | |||
50 | #include "llvm/IR/GlobalVariable.h" | |||
51 | #include "llvm/IR/InstrTypes.h" | |||
52 | #include "llvm/IR/Instruction.h" | |||
53 | #include "llvm/IR/Instructions.h" | |||
54 | #include "llvm/IR/IntrinsicInst.h" | |||
55 | #include "llvm/IR/Intrinsics.h" | |||
56 | #include "llvm/IR/IntrinsicsAArch64.h" | |||
57 | #include "llvm/IR/IntrinsicsRISCV.h" | |||
58 | #include "llvm/IR/IntrinsicsX86.h" | |||
59 | #include "llvm/IR/LLVMContext.h" | |||
60 | #include "llvm/IR/Metadata.h" | |||
61 | #include "llvm/IR/Module.h" | |||
62 | #include "llvm/IR/Operator.h" | |||
63 | #include "llvm/IR/PatternMatch.h" | |||
64 | #include "llvm/IR/Type.h" | |||
65 | #include "llvm/IR/User.h" | |||
66 | #include "llvm/IR/Value.h" | |||
67 | #include "llvm/Support/Casting.h" | |||
68 | #include "llvm/Support/CommandLine.h" | |||
69 | #include "llvm/Support/Compiler.h" | |||
70 | #include "llvm/Support/ErrorHandling.h" | |||
71 | #include "llvm/Support/KnownBits.h" | |||
72 | #include "llvm/Support/MathExtras.h" | |||
73 | #include <algorithm> | |||
74 | #include <cassert> | |||
75 | #include <cstdint> | |||
76 | #include <optional> | |||
77 | #include <utility> | |||
78 | ||||
79 | using namespace llvm; | |||
80 | using namespace llvm::PatternMatch; | |||
81 | ||||
82 | // Controls the number of uses of the value searched for possible | |||
83 | // dominating comparisons. | |||
84 | static cl::opt<unsigned> DomConditionsMaxUses("dom-conditions-max-uses", | |||
85 | cl::Hidden, cl::init(20)); | |||
86 | ||||
87 | ||||
88 | /// Returns the bitwidth of the given scalar or pointer type. For vector types, | |||
89 | /// returns the element type's bitwidth. | |||
90 | static unsigned getBitWidth(Type *Ty, const DataLayout &DL) { | |||
91 | if (unsigned BitWidth = Ty->getScalarSizeInBits()) | |||
92 | return BitWidth; | |||
93 | ||||
94 | return DL.getPointerTypeSizeInBits(Ty); | |||
95 | } | |||
96 | ||||
97 | namespace { | |||
98 | ||||
99 | // Simplifying using an assume can only be done in a particular control-flow | |||
100 | // context (the context instruction provides that context). If an assume and | |||
101 | // the context instruction are not in the same block then the DT helps in | |||
102 | // figuring out if we can use it. | |||
103 | struct Query { | |||
104 | const DataLayout &DL; | |||
105 | AssumptionCache *AC; | |||
106 | const Instruction *CxtI; | |||
107 | const DominatorTree *DT; | |||
108 | ||||
109 | // Unlike the other analyses, this may be a nullptr because not all clients | |||
110 | // provide it currently. | |||
111 | OptimizationRemarkEmitter *ORE; | |||
112 | ||||
113 | /// If true, it is safe to use metadata during simplification. | |||
114 | InstrInfoQuery IIQ; | |||
115 | ||||
116 | Query(const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, | |||
117 | const DominatorTree *DT, bool UseInstrInfo, | |||
118 | OptimizationRemarkEmitter *ORE = nullptr) | |||
119 | : DL(DL), AC(AC), CxtI(CxtI), DT(DT), ORE(ORE), IIQ(UseInstrInfo) {} | |||
120 | }; | |||
121 | ||||
122 | } // end anonymous namespace | |||
123 | ||||
124 | // Given the provided Value and, potentially, a context instruction, return | |||
125 | // the preferred context instruction (if any). | |||
126 | static const Instruction *safeCxtI(const Value *V, const Instruction *CxtI) { | |||
127 | // If we've been provided with a context instruction, then use that (provided | |||
128 | // it has been inserted). | |||
129 | if (CxtI && CxtI->getParent()) | |||
130 | return CxtI; | |||
131 | ||||
132 | // If the value is really an already-inserted instruction, then use that. | |||
133 | CxtI = dyn_cast<Instruction>(V); | |||
134 | if (CxtI && CxtI->getParent()) | |||
135 | return CxtI; | |||
136 | ||||
137 | return nullptr; | |||
138 | } | |||
139 | ||||
140 | static const Instruction *safeCxtI(const Value *V1, const Value *V2, const Instruction *CxtI) { | |||
141 | // If we've been provided with a context instruction, then use that (provided | |||
142 | // it has been inserted). | |||
143 | if (CxtI && CxtI->getParent()) | |||
144 | return CxtI; | |||
145 | ||||
146 | // If the value is really an already-inserted instruction, then use that. | |||
147 | CxtI = dyn_cast<Instruction>(V1); | |||
148 | if (CxtI && CxtI->getParent()) | |||
149 | return CxtI; | |||
150 | ||||
151 | CxtI = dyn_cast<Instruction>(V2); | |||
152 | if (CxtI && CxtI->getParent()) | |||
153 | return CxtI; | |||
154 | ||||
155 | return nullptr; | |||
156 | } | |||
157 | ||||
158 | static bool getShuffleDemandedElts(const ShuffleVectorInst *Shuf, | |||
159 | const APInt &DemandedElts, | |||
160 | APInt &DemandedLHS, APInt &DemandedRHS) { | |||
161 | if (isa<ScalableVectorType>(Shuf->getType())) { | |||
162 | assert(DemandedElts == APInt(1,1))(static_cast <bool> (DemandedElts == APInt(1,1)) ? void (0) : __assert_fail ("DemandedElts == APInt(1,1)", "llvm/lib/Analysis/ValueTracking.cpp" , 162, __extension__ __PRETTY_FUNCTION__)); | |||
163 | DemandedLHS = DemandedRHS = DemandedElts; | |||
164 | return true; | |||
165 | } | |||
166 | ||||
167 | int NumElts = | |||
168 | cast<FixedVectorType>(Shuf->getOperand(0)->getType())->getNumElements(); | |||
169 | return llvm::getShuffleDemandedElts(NumElts, Shuf->getShuffleMask(), | |||
170 | DemandedElts, DemandedLHS, DemandedRHS); | |||
171 | } | |||
172 | ||||
173 | static void computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
174 | KnownBits &Known, unsigned Depth, const Query &Q); | |||
175 | ||||
176 | static void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth, | |||
177 | const Query &Q) { | |||
178 | // Since the number of lanes in a scalable vector is unknown at compile time, | |||
179 | // we track one bit which is implicitly broadcast to all lanes. This means | |||
180 | // that all lanes in a scalable vector are considered demanded. | |||
181 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
182 | APInt DemandedElts = | |||
183 | FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1); | |||
184 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
185 | } | |||
186 | ||||
187 | void llvm::computeKnownBits(const Value *V, KnownBits &Known, | |||
188 | const DataLayout &DL, unsigned Depth, | |||
189 | AssumptionCache *AC, const Instruction *CxtI, | |||
190 | const DominatorTree *DT, | |||
191 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
192 | ::computeKnownBits(V, Known, Depth, | |||
193 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
194 | } | |||
195 | ||||
196 | void llvm::computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
197 | KnownBits &Known, const DataLayout &DL, | |||
198 | unsigned Depth, AssumptionCache *AC, | |||
199 | const Instruction *CxtI, const DominatorTree *DT, | |||
200 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
201 | ::computeKnownBits(V, DemandedElts, Known, Depth, | |||
202 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
203 | } | |||
204 | ||||
205 | static KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
206 | unsigned Depth, const Query &Q); | |||
207 | ||||
208 | static KnownBits computeKnownBits(const Value *V, unsigned Depth, | |||
209 | const Query &Q); | |||
210 | ||||
211 | KnownBits llvm::computeKnownBits(const Value *V, const DataLayout &DL, | |||
212 | unsigned Depth, AssumptionCache *AC, | |||
213 | const Instruction *CxtI, | |||
214 | const DominatorTree *DT, | |||
215 | OptimizationRemarkEmitter *ORE, | |||
216 | bool UseInstrInfo) { | |||
217 | return ::computeKnownBits( | |||
218 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
219 | } | |||
220 | ||||
221 | KnownBits llvm::computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
222 | const DataLayout &DL, unsigned Depth, | |||
223 | AssumptionCache *AC, const Instruction *CxtI, | |||
224 | const DominatorTree *DT, | |||
225 | OptimizationRemarkEmitter *ORE, | |||
226 | bool UseInstrInfo) { | |||
227 | return ::computeKnownBits( | |||
228 | V, DemandedElts, Depth, | |||
229 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
230 | } | |||
231 | ||||
232 | bool llvm::haveNoCommonBitsSet(const Value *LHS, const Value *RHS, | |||
233 | const DataLayout &DL, AssumptionCache *AC, | |||
234 | const Instruction *CxtI, const DominatorTree *DT, | |||
235 | bool UseInstrInfo) { | |||
236 | assert(LHS->getType() == RHS->getType() &&(static_cast <bool> (LHS->getType() == RHS->getType () && "LHS and RHS should have the same type") ? void (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\"" , "llvm/lib/Analysis/ValueTracking.cpp", 237, __extension__ __PRETTY_FUNCTION__ )) | |||
237 | "LHS and RHS should have the same type")(static_cast <bool> (LHS->getType() == RHS->getType () && "LHS and RHS should have the same type") ? void (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\"" , "llvm/lib/Analysis/ValueTracking.cpp", 237, __extension__ __PRETTY_FUNCTION__ )); | |||
238 | assert(LHS->getType()->isIntOrIntVectorTy() &&(static_cast <bool> (LHS->getType()->isIntOrIntVectorTy () && "LHS and RHS should be integers") ? void (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\"" , "llvm/lib/Analysis/ValueTracking.cpp", 239, __extension__ __PRETTY_FUNCTION__ )) | |||
239 | "LHS and RHS should be integers")(static_cast <bool> (LHS->getType()->isIntOrIntVectorTy () && "LHS and RHS should be integers") ? void (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\"" , "llvm/lib/Analysis/ValueTracking.cpp", 239, __extension__ __PRETTY_FUNCTION__ )); | |||
240 | // Look for an inverted mask: (X & ~M) op (Y & M). | |||
241 | { | |||
242 | Value *M; | |||
243 | if (match(LHS, m_c_And(m_Not(m_Value(M)), m_Value())) && | |||
244 | match(RHS, m_c_And(m_Specific(M), m_Value()))) | |||
245 | return true; | |||
246 | if (match(RHS, m_c_And(m_Not(m_Value(M)), m_Value())) && | |||
247 | match(LHS, m_c_And(m_Specific(M), m_Value()))) | |||
248 | return true; | |||
249 | } | |||
250 | ||||
251 | // X op (Y & ~X) | |||
252 | if (match(RHS, m_c_And(m_Not(m_Specific(LHS)), m_Value())) || | |||
253 | match(LHS, m_c_And(m_Not(m_Specific(RHS)), m_Value()))) | |||
254 | return true; | |||
255 | ||||
256 | // X op ((X & Y) ^ Y) -- this is the canonical form of the previous pattern | |||
257 | // for constant Y. | |||
258 | Value *Y; | |||
259 | if (match(RHS, | |||
260 | m_c_Xor(m_c_And(m_Specific(LHS), m_Value(Y)), m_Deferred(Y))) || | |||
261 | match(LHS, m_c_Xor(m_c_And(m_Specific(RHS), m_Value(Y)), m_Deferred(Y)))) | |||
262 | return true; | |||
263 | ||||
264 | // Peek through extends to find a 'not' of the other side: | |||
265 | // (ext Y) op ext(~Y) | |||
266 | // (ext ~Y) op ext(Y) | |||
267 | if ((match(LHS, m_ZExtOrSExt(m_Value(Y))) && | |||
268 | match(RHS, m_ZExtOrSExt(m_Not(m_Specific(Y))))) || | |||
269 | (match(RHS, m_ZExtOrSExt(m_Value(Y))) && | |||
270 | match(LHS, m_ZExtOrSExt(m_Not(m_Specific(Y)))))) | |||
271 | return true; | |||
272 | ||||
273 | // Look for: (A & B) op ~(A | B) | |||
274 | { | |||
275 | Value *A, *B; | |||
276 | if (match(LHS, m_And(m_Value(A), m_Value(B))) && | |||
277 | match(RHS, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) | |||
278 | return true; | |||
279 | if (match(RHS, m_And(m_Value(A), m_Value(B))) && | |||
280 | match(LHS, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))) | |||
281 | return true; | |||
282 | } | |||
283 | IntegerType *IT = cast<IntegerType>(LHS->getType()->getScalarType()); | |||
284 | KnownBits LHSKnown(IT->getBitWidth()); | |||
285 | KnownBits RHSKnown(IT->getBitWidth()); | |||
286 | computeKnownBits(LHS, LHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
287 | computeKnownBits(RHS, RHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
288 | return KnownBits::haveNoCommonBitsSet(LHSKnown, RHSKnown); | |||
289 | } | |||
290 | ||||
291 | bool llvm::isOnlyUsedInZeroEqualityComparison(const Instruction *I) { | |||
292 | return !I->user_empty() && all_of(I->users(), [](const User *U) { | |||
293 | ICmpInst::Predicate P; | |||
294 | return match(U, m_ICmp(P, m_Value(), m_Zero())) && ICmpInst::isEquality(P); | |||
295 | }); | |||
296 | } | |||
297 | ||||
298 | static bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, | |||
299 | const Query &Q); | |||
300 | ||||
301 | bool llvm::isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL, | |||
302 | bool OrZero, unsigned Depth, | |||
303 | AssumptionCache *AC, const Instruction *CxtI, | |||
304 | const DominatorTree *DT, bool UseInstrInfo) { | |||
305 | return ::isKnownToBeAPowerOfTwo( | |||
306 | V, OrZero, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
307 | } | |||
308 | ||||
309 | static bool isKnownNonZero(const Value *V, const APInt &DemandedElts, | |||
310 | unsigned Depth, const Query &Q); | |||
311 | ||||
312 | static bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q); | |||
313 | ||||
314 | bool llvm::isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth, | |||
315 | AssumptionCache *AC, const Instruction *CxtI, | |||
316 | const DominatorTree *DT, bool UseInstrInfo) { | |||
317 | return ::isKnownNonZero(V, Depth, | |||
318 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
319 | } | |||
320 | ||||
321 | bool llvm::isKnownNonNegative(const Value *V, const DataLayout &DL, | |||
322 | unsigned Depth, AssumptionCache *AC, | |||
323 | const Instruction *CxtI, const DominatorTree *DT, | |||
324 | bool UseInstrInfo) { | |||
325 | KnownBits Known = | |||
326 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
327 | return Known.isNonNegative(); | |||
328 | } | |||
329 | ||||
330 | bool llvm::isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth, | |||
331 | AssumptionCache *AC, const Instruction *CxtI, | |||
332 | const DominatorTree *DT, bool UseInstrInfo) { | |||
333 | if (auto *CI = dyn_cast<ConstantInt>(V)) | |||
334 | return CI->getValue().isStrictlyPositive(); | |||
335 | ||||
336 | // TODO: We'd doing two recursive queries here. We should factor this such | |||
337 | // that only a single query is needed. | |||
338 | return isKnownNonNegative(V, DL, Depth, AC, CxtI, DT, UseInstrInfo) && | |||
339 | isKnownNonZero(V, DL, Depth, AC, CxtI, DT, UseInstrInfo); | |||
340 | } | |||
341 | ||||
342 | bool llvm::isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth, | |||
343 | AssumptionCache *AC, const Instruction *CxtI, | |||
344 | const DominatorTree *DT, bool UseInstrInfo) { | |||
345 | KnownBits Known = | |||
346 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
347 | return Known.isNegative(); | |||
348 | } | |||
349 | ||||
350 | static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth, | |||
351 | const Query &Q); | |||
352 | ||||
353 | bool llvm::isKnownNonEqual(const Value *V1, const Value *V2, | |||
354 | const DataLayout &DL, AssumptionCache *AC, | |||
355 | const Instruction *CxtI, const DominatorTree *DT, | |||
356 | bool UseInstrInfo) { | |||
357 | return ::isKnownNonEqual(V1, V2, 0, | |||
358 | Query(DL, AC, safeCxtI(V2, V1, CxtI), DT, | |||
359 | UseInstrInfo, /*ORE=*/nullptr)); | |||
360 | } | |||
361 | ||||
362 | static bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, | |||
363 | const Query &Q); | |||
364 | ||||
365 | bool llvm::MaskedValueIsZero(const Value *V, const APInt &Mask, | |||
366 | const DataLayout &DL, unsigned Depth, | |||
367 | AssumptionCache *AC, const Instruction *CxtI, | |||
368 | const DominatorTree *DT, bool UseInstrInfo) { | |||
369 | return ::MaskedValueIsZero( | |||
370 | V, Mask, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
371 | } | |||
372 | ||||
373 | static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts, | |||
374 | unsigned Depth, const Query &Q); | |||
375 | ||||
376 | static unsigned ComputeNumSignBits(const Value *V, unsigned Depth, | |||
377 | const Query &Q) { | |||
378 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
379 | APInt DemandedElts = | |||
380 | FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1); | |||
381 | return ComputeNumSignBits(V, DemandedElts, Depth, Q); | |||
382 | } | |||
383 | ||||
384 | unsigned llvm::ComputeNumSignBits(const Value *V, const DataLayout &DL, | |||
385 | unsigned Depth, AssumptionCache *AC, | |||
386 | const Instruction *CxtI, | |||
387 | const DominatorTree *DT, bool UseInstrInfo) { | |||
388 | return ::ComputeNumSignBits( | |||
389 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
390 | } | |||
391 | ||||
392 | unsigned llvm::ComputeMaxSignificantBits(const Value *V, const DataLayout &DL, | |||
393 | unsigned Depth, AssumptionCache *AC, | |||
394 | const Instruction *CxtI, | |||
395 | const DominatorTree *DT) { | |||
396 | unsigned SignBits = ComputeNumSignBits(V, DL, Depth, AC, CxtI, DT); | |||
397 | return V->getType()->getScalarSizeInBits() - SignBits + 1; | |||
398 | } | |||
399 | ||||
400 | static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1, | |||
401 | bool NSW, const APInt &DemandedElts, | |||
402 | KnownBits &KnownOut, KnownBits &Known2, | |||
403 | unsigned Depth, const Query &Q) { | |||
404 | computeKnownBits(Op1, DemandedElts, KnownOut, Depth + 1, Q); | |||
405 | ||||
406 | // If one operand is unknown and we have no nowrap information, | |||
407 | // the result will be unknown independently of the second operand. | |||
408 | if (KnownOut.isUnknown() && !NSW) | |||
409 | return; | |||
410 | ||||
411 | computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q); | |||
412 | KnownOut = KnownBits::computeForAddSub(Add, NSW, Known2, KnownOut); | |||
413 | } | |||
414 | ||||
415 | static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW, | |||
416 | const APInt &DemandedElts, KnownBits &Known, | |||
417 | KnownBits &Known2, unsigned Depth, | |||
418 | const Query &Q) { | |||
419 | computeKnownBits(Op1, DemandedElts, Known, Depth + 1, Q); | |||
420 | computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q); | |||
421 | ||||
422 | bool isKnownNegative = false; | |||
423 | bool isKnownNonNegative = false; | |||
424 | // If the multiplication is known not to overflow, compute the sign bit. | |||
425 | if (NSW) { | |||
426 | if (Op0 == Op1) { | |||
427 | // The product of a number with itself is non-negative. | |||
428 | isKnownNonNegative = true; | |||
429 | } else { | |||
430 | bool isKnownNonNegativeOp1 = Known.isNonNegative(); | |||
431 | bool isKnownNonNegativeOp0 = Known2.isNonNegative(); | |||
432 | bool isKnownNegativeOp1 = Known.isNegative(); | |||
433 | bool isKnownNegativeOp0 = Known2.isNegative(); | |||
434 | // The product of two numbers with the same sign is non-negative. | |||
435 | isKnownNonNegative = (isKnownNegativeOp1 && isKnownNegativeOp0) || | |||
436 | (isKnownNonNegativeOp1 && isKnownNonNegativeOp0); | |||
437 | // The product of a negative number and a non-negative number is either | |||
438 | // negative or zero. | |||
439 | if (!isKnownNonNegative) | |||
440 | isKnownNegative = | |||
441 | (isKnownNegativeOp1 && isKnownNonNegativeOp0 && | |||
442 | Known2.isNonZero()) || | |||
443 | (isKnownNegativeOp0 && isKnownNonNegativeOp1 && Known.isNonZero()); | |||
444 | } | |||
445 | } | |||
446 | ||||
447 | bool SelfMultiply = Op0 == Op1; | |||
448 | // TODO: SelfMultiply can be poison, but not undef. | |||
449 | if (SelfMultiply) | |||
450 | SelfMultiply &= | |||
451 | isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT, Depth + 1); | |||
452 | Known = KnownBits::mul(Known, Known2, SelfMultiply); | |||
453 | ||||
454 | // Only make use of no-wrap flags if we failed to compute the sign bit | |||
455 | // directly. This matters if the multiplication always overflows, in | |||
456 | // which case we prefer to follow the result of the direct computation, | |||
457 | // though as the program is invoking undefined behaviour we can choose | |||
458 | // whatever we like here. | |||
459 | if (isKnownNonNegative && !Known.isNegative()) | |||
460 | Known.makeNonNegative(); | |||
461 | else if (isKnownNegative && !Known.isNonNegative()) | |||
462 | Known.makeNegative(); | |||
463 | } | |||
464 | ||||
465 | void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges, | |||
466 | KnownBits &Known) { | |||
467 | unsigned BitWidth = Known.getBitWidth(); | |||
468 | unsigned NumRanges = Ranges.getNumOperands() / 2; | |||
469 | assert(NumRanges >= 1)(static_cast <bool> (NumRanges >= 1) ? void (0) : __assert_fail ("NumRanges >= 1", "llvm/lib/Analysis/ValueTracking.cpp", 469, __extension__ __PRETTY_FUNCTION__)); | |||
470 | ||||
471 | Known.Zero.setAllBits(); | |||
472 | Known.One.setAllBits(); | |||
473 | ||||
474 | for (unsigned i = 0; i < NumRanges; ++i) { | |||
475 | ConstantInt *Lower = | |||
476 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 0)); | |||
477 | ConstantInt *Upper = | |||
478 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1)); | |||
479 | ConstantRange Range(Lower->getValue(), Upper->getValue()); | |||
480 | ||||
481 | // The first CommonPrefixBits of all values in Range are equal. | |||
482 | unsigned CommonPrefixBits = | |||
483 | (Range.getUnsignedMax() ^ Range.getUnsignedMin()).countl_zero(); | |||
484 | APInt Mask = APInt::getHighBitsSet(BitWidth, CommonPrefixBits); | |||
485 | APInt UnsignedMax = Range.getUnsignedMax().zextOrTrunc(BitWidth); | |||
486 | Known.One &= UnsignedMax & Mask; | |||
487 | Known.Zero &= ~UnsignedMax & Mask; | |||
488 | } | |||
489 | } | |||
490 | ||||
491 | static bool isEphemeralValueOf(const Instruction *I, const Value *E) { | |||
492 | SmallVector<const Value *, 16> WorkSet(1, I); | |||
493 | SmallPtrSet<const Value *, 32> Visited; | |||
494 | SmallPtrSet<const Value *, 16> EphValues; | |||
495 | ||||
496 | // The instruction defining an assumption's condition itself is always | |||
497 | // considered ephemeral to that assumption (even if it has other | |||
498 | // non-ephemeral users). See r246696's test case for an example. | |||
499 | if (is_contained(I->operands(), E)) | |||
500 | return true; | |||
501 | ||||
502 | while (!WorkSet.empty()) { | |||
503 | const Value *V = WorkSet.pop_back_val(); | |||
504 | if (!Visited.insert(V).second) | |||
505 | continue; | |||
506 | ||||
507 | // If all uses of this value are ephemeral, then so is this value. | |||
508 | if (llvm::all_of(V->users(), [&](const User *U) { | |||
509 | return EphValues.count(U); | |||
510 | })) { | |||
511 | if (V == E) | |||
512 | return true; | |||
513 | ||||
514 | if (V == I || (isa<Instruction>(V) && | |||
515 | !cast<Instruction>(V)->mayHaveSideEffects() && | |||
516 | !cast<Instruction>(V)->isTerminator())) { | |||
517 | EphValues.insert(V); | |||
518 | if (const User *U = dyn_cast<User>(V)) | |||
519 | append_range(WorkSet, U->operands()); | |||
520 | } | |||
521 | } | |||
522 | } | |||
523 | ||||
524 | return false; | |||
525 | } | |||
526 | ||||
527 | // Is this an intrinsic that cannot be speculated but also cannot trap? | |||
528 | bool llvm::isAssumeLikeIntrinsic(const Instruction *I) { | |||
529 | if (const IntrinsicInst *CI = dyn_cast<IntrinsicInst>(I)) | |||
530 | return CI->isAssumeLikeIntrinsic(); | |||
531 | ||||
532 | return false; | |||
533 | } | |||
534 | ||||
535 | bool llvm::isValidAssumeForContext(const Instruction *Inv, | |||
536 | const Instruction *CxtI, | |||
537 | const DominatorTree *DT) { | |||
538 | // There are two restrictions on the use of an assume: | |||
539 | // 1. The assume must dominate the context (or the control flow must | |||
540 | // reach the assume whenever it reaches the context). | |||
541 | // 2. The context must not be in the assume's set of ephemeral values | |||
542 | // (otherwise we will use the assume to prove that the condition | |||
543 | // feeding the assume is trivially true, thus causing the removal of | |||
544 | // the assume). | |||
545 | ||||
546 | if (Inv->getParent() == CxtI->getParent()) { | |||
547 | // If Inv and CtxI are in the same block, check if the assume (Inv) is first | |||
548 | // in the BB. | |||
549 | if (Inv->comesBefore(CxtI)) | |||
550 | return true; | |||
551 | ||||
552 | // Don't let an assume affect itself - this would cause the problems | |||
553 | // `isEphemeralValueOf` is trying to prevent, and it would also make | |||
554 | // the loop below go out of bounds. | |||
555 | if (Inv == CxtI) | |||
556 | return false; | |||
557 | ||||
558 | // The context comes first, but they're both in the same block. | |||
559 | // Make sure there is nothing in between that might interrupt | |||
560 | // the control flow, not even CxtI itself. | |||
561 | // We limit the scan distance between the assume and its context instruction | |||
562 | // to avoid a compile-time explosion. This limit is chosen arbitrarily, so | |||
563 | // it can be adjusted if needed (could be turned into a cl::opt). | |||
564 | auto Range = make_range(CxtI->getIterator(), Inv->getIterator()); | |||
565 | if (!isGuaranteedToTransferExecutionToSuccessor(Range, 15)) | |||
566 | return false; | |||
567 | ||||
568 | return !isEphemeralValueOf(Inv, CxtI); | |||
569 | } | |||
570 | ||||
571 | // Inv and CxtI are in different blocks. | |||
572 | if (DT) { | |||
573 | if (DT->dominates(Inv, CxtI)) | |||
574 | return true; | |||
575 | } else if (Inv->getParent() == CxtI->getParent()->getSinglePredecessor()) { | |||
576 | // We don't have a DT, but this trivially dominates. | |||
577 | return true; | |||
578 | } | |||
579 | ||||
580 | return false; | |||
581 | } | |||
582 | ||||
583 | static bool cmpExcludesZero(CmpInst::Predicate Pred, const Value *RHS) { | |||
584 | // v u> y implies v != 0. | |||
585 | if (Pred == ICmpInst::ICMP_UGT) | |||
586 | return true; | |||
587 | ||||
588 | // Special-case v != 0 to also handle v != null. | |||
589 | if (Pred == ICmpInst::ICMP_NE) | |||
590 | return match(RHS, m_Zero()); | |||
591 | ||||
592 | // All other predicates - rely on generic ConstantRange handling. | |||
593 | const APInt *C; | |||
594 | if (!match(RHS, m_APInt(C))) | |||
595 | return false; | |||
596 | ||||
597 | ConstantRange TrueValues = ConstantRange::makeExactICmpRegion(Pred, *C); | |||
598 | return !TrueValues.contains(APInt::getZero(C->getBitWidth())); | |||
599 | } | |||
600 | ||||
601 | static bool isKnownNonZeroFromAssume(const Value *V, const Query &Q) { | |||
602 | // Use of assumptions is context-sensitive. If we don't have a context, we | |||
603 | // cannot use them! | |||
604 | if (!Q.AC || !Q.CxtI) | |||
605 | return false; | |||
606 | ||||
607 | if (Q.CxtI && V->getType()->isPointerTy()) { | |||
608 | SmallVector<Attribute::AttrKind, 2> AttrKinds{Attribute::NonNull}; | |||
609 | if (!NullPointerIsDefined(Q.CxtI->getFunction(), | |||
610 | V->getType()->getPointerAddressSpace())) | |||
611 | AttrKinds.push_back(Attribute::Dereferenceable); | |||
612 | ||||
613 | if (getKnowledgeValidInContext(V, AttrKinds, Q.CxtI, Q.DT, Q.AC)) | |||
614 | return true; | |||
615 | } | |||
616 | ||||
617 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { | |||
618 | if (!AssumeVH) | |||
619 | continue; | |||
620 | CallInst *I = cast<CallInst>(AssumeVH); | |||
621 | assert(I->getFunction() == Q.CxtI->getFunction() &&(static_cast <bool> (I->getFunction() == Q.CxtI-> getFunction() && "Got assumption for the wrong function!" ) ? void (0) : __assert_fail ("I->getFunction() == Q.CxtI->getFunction() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 622, __extension__ __PRETTY_FUNCTION__ )) | |||
622 | "Got assumption for the wrong function!")(static_cast <bool> (I->getFunction() == Q.CxtI-> getFunction() && "Got assumption for the wrong function!" ) ? void (0) : __assert_fail ("I->getFunction() == Q.CxtI->getFunction() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 622, __extension__ __PRETTY_FUNCTION__ )); | |||
623 | ||||
624 | // Warning: This loop can end up being somewhat performance sensitive. | |||
625 | // We're running this loop for once for each value queried resulting in a | |||
626 | // runtime of ~O(#assumes * #values). | |||
627 | ||||
628 | assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 629, __extension__ __PRETTY_FUNCTION__ )) | |||
629 | "must be an assume intrinsic")(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 629, __extension__ __PRETTY_FUNCTION__ )); | |||
630 | ||||
631 | Value *RHS; | |||
632 | CmpInst::Predicate Pred; | |||
633 | auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V))); | |||
634 | if (!match(I->getArgOperand(0), m_c_ICmp(Pred, m_V, m_Value(RHS)))) | |||
635 | return false; | |||
636 | ||||
637 | if (cmpExcludesZero(Pred, RHS) && isValidAssumeForContext(I, Q.CxtI, Q.DT)) | |||
638 | return true; | |||
639 | } | |||
640 | ||||
641 | return false; | |||
642 | } | |||
643 | ||||
644 | static void computeKnownBitsFromCmp(const Value *V, const ICmpInst *Cmp, | |||
645 | KnownBits &Known, unsigned Depth, | |||
646 | const Query &Q) { | |||
647 | unsigned BitWidth = Known.getBitWidth(); | |||
648 | // We are attempting to compute known bits for the operands of an assume. | |||
649 | // Do not try to use other assumptions for those recursive calls because | |||
650 | // that can lead to mutual recursion and a compile-time explosion. | |||
651 | // An example of the mutual recursion: computeKnownBits can call | |||
652 | // isKnownNonZero which calls computeKnownBitsFromAssume (this function) | |||
653 | // and so on. | |||
654 | Query QueryNoAC = Q; | |||
655 | QueryNoAC.AC = nullptr; | |||
656 | ||||
657 | // Note that ptrtoint may change the bitwidth. | |||
658 | Value *A, *B; | |||
659 | auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V))); | |||
660 | ||||
661 | CmpInst::Predicate Pred; | |||
662 | uint64_t C; | |||
663 | switch (Cmp->getPredicate()) { | |||
664 | default: | |||
665 | break; | |||
666 | case ICmpInst::ICMP_EQ: | |||
667 | // assume(v = a) | |||
668 | if (match(Cmp, m_c_ICmp(Pred, m_V, m_Value(A)))) { | |||
669 | KnownBits RHSKnown = | |||
670 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
671 | Known.Zero |= RHSKnown.Zero; | |||
672 | Known.One |= RHSKnown.One; | |||
673 | // assume(v & b = a) | |||
674 | } else if (match(Cmp, | |||
675 | m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)), m_Value(A)))) { | |||
676 | KnownBits RHSKnown = | |||
677 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
678 | KnownBits MaskKnown = | |||
679 | computeKnownBits(B, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
680 | ||||
681 | // For those bits in the mask that are known to be one, we can propagate | |||
682 | // known bits from the RHS to V. | |||
683 | Known.Zero |= RHSKnown.Zero & MaskKnown.One; | |||
684 | Known.One |= RHSKnown.One & MaskKnown.One; | |||
685 | // assume(~(v & b) = a) | |||
686 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))), | |||
687 | m_Value(A)))) { | |||
688 | KnownBits RHSKnown = | |||
689 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
690 | KnownBits MaskKnown = | |||
691 | computeKnownBits(B, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
692 | ||||
693 | // For those bits in the mask that are known to be one, we can propagate | |||
694 | // inverted known bits from the RHS to V. | |||
695 | Known.Zero |= RHSKnown.One & MaskKnown.One; | |||
696 | Known.One |= RHSKnown.Zero & MaskKnown.One; | |||
697 | // assume(v | b = a) | |||
698 | } else if (match(Cmp, | |||
699 | m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), m_Value(A)))) { | |||
700 | KnownBits RHSKnown = | |||
701 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
702 | KnownBits BKnown = | |||
703 | computeKnownBits(B, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
704 | ||||
705 | // For those bits in B that are known to be zero, we can propagate known | |||
706 | // bits from the RHS to V. | |||
707 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; | |||
708 | Known.One |= RHSKnown.One & BKnown.Zero; | |||
709 | // assume(~(v | b) = a) | |||
710 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))), | |||
711 | m_Value(A)))) { | |||
712 | KnownBits RHSKnown = | |||
713 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
714 | KnownBits BKnown = | |||
715 | computeKnownBits(B, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
716 | ||||
717 | // For those bits in B that are known to be zero, we can propagate | |||
718 | // inverted known bits from the RHS to V. | |||
719 | Known.Zero |= RHSKnown.One & BKnown.Zero; | |||
720 | Known.One |= RHSKnown.Zero & BKnown.Zero; | |||
721 | // assume(v ^ b = a) | |||
722 | } else if (match(Cmp, | |||
723 | m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), m_Value(A)))) { | |||
724 | KnownBits RHSKnown = | |||
725 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
726 | KnownBits BKnown = | |||
727 | computeKnownBits(B, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
728 | ||||
729 | // For those bits in B that are known to be zero, we can propagate known | |||
730 | // bits from the RHS to V. For those bits in B that are known to be one, | |||
731 | // we can propagate inverted known bits from the RHS to V. | |||
732 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; | |||
733 | Known.One |= RHSKnown.One & BKnown.Zero; | |||
734 | Known.Zero |= RHSKnown.One & BKnown.One; | |||
735 | Known.One |= RHSKnown.Zero & BKnown.One; | |||
736 | // assume(~(v ^ b) = a) | |||
737 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))), | |||
738 | m_Value(A)))) { | |||
739 | KnownBits RHSKnown = | |||
740 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
741 | KnownBits BKnown = | |||
742 | computeKnownBits(B, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
743 | ||||
744 | // For those bits in B that are known to be zero, we can propagate | |||
745 | // inverted known bits from the RHS to V. For those bits in B that are | |||
746 | // known to be one, we can propagate known bits from the RHS to V. | |||
747 | Known.Zero |= RHSKnown.One & BKnown.Zero; | |||
748 | Known.One |= RHSKnown.Zero & BKnown.Zero; | |||
749 | Known.Zero |= RHSKnown.Zero & BKnown.One; | |||
750 | Known.One |= RHSKnown.One & BKnown.One; | |||
751 | // assume(v << c = a) | |||
752 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)), | |||
753 | m_Value(A))) && | |||
754 | C < BitWidth) { | |||
755 | KnownBits RHSKnown = | |||
756 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
757 | ||||
758 | // For those bits in RHS that are known, we can propagate them to known | |||
759 | // bits in V shifted to the right by C. | |||
760 | RHSKnown.Zero.lshrInPlace(C); | |||
761 | Known.Zero |= RHSKnown.Zero; | |||
762 | RHSKnown.One.lshrInPlace(C); | |||
763 | Known.One |= RHSKnown.One; | |||
764 | // assume(~(v << c) = a) | |||
765 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))), | |||
766 | m_Value(A))) && | |||
767 | C < BitWidth) { | |||
768 | KnownBits RHSKnown = | |||
769 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
770 | // For those bits in RHS that are known, we can propagate them inverted | |||
771 | // to known bits in V shifted to the right by C. | |||
772 | RHSKnown.One.lshrInPlace(C); | |||
773 | Known.Zero |= RHSKnown.One; | |||
774 | RHSKnown.Zero.lshrInPlace(C); | |||
775 | Known.One |= RHSKnown.Zero; | |||
776 | // assume(v >> c = a) | |||
777 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shr(m_V, m_ConstantInt(C)), | |||
778 | m_Value(A))) && | |||
779 | C < BitWidth) { | |||
780 | KnownBits RHSKnown = | |||
781 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
782 | // For those bits in RHS that are known, we can propagate them to known | |||
783 | // bits in V shifted to the right by C. | |||
784 | Known.Zero |= RHSKnown.Zero << C; | |||
785 | Known.One |= RHSKnown.One << C; | |||
786 | // assume(~(v >> c) = a) | |||
787 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shr(m_V, m_ConstantInt(C))), | |||
788 | m_Value(A))) && | |||
789 | C < BitWidth) { | |||
790 | KnownBits RHSKnown = | |||
791 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
792 | // For those bits in RHS that are known, we can propagate them inverted | |||
793 | // to known bits in V shifted to the right by C. | |||
794 | Known.Zero |= RHSKnown.One << C; | |||
795 | Known.One |= RHSKnown.Zero << C; | |||
796 | } | |||
797 | break; | |||
798 | case ICmpInst::ICMP_SGE: | |||
799 | // assume(v >=_s c) where c is non-negative | |||
800 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A)))) { | |||
801 | KnownBits RHSKnown = | |||
802 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
803 | ||||
804 | if (RHSKnown.isNonNegative()) { | |||
805 | // We know that the sign bit is zero. | |||
806 | Known.makeNonNegative(); | |||
807 | } | |||
808 | } | |||
809 | break; | |||
810 | case ICmpInst::ICMP_SGT: | |||
811 | // assume(v >_s c) where c is at least -1. | |||
812 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A)))) { | |||
813 | KnownBits RHSKnown = | |||
814 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
815 | ||||
816 | if (RHSKnown.isAllOnes() || RHSKnown.isNonNegative()) { | |||
817 | // We know that the sign bit is zero. | |||
818 | Known.makeNonNegative(); | |||
819 | } | |||
820 | } | |||
821 | break; | |||
822 | case ICmpInst::ICMP_SLE: | |||
823 | // assume(v <=_s c) where c is negative | |||
824 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A)))) { | |||
825 | KnownBits RHSKnown = | |||
826 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
827 | ||||
828 | if (RHSKnown.isNegative()) { | |||
829 | // We know that the sign bit is one. | |||
830 | Known.makeNegative(); | |||
831 | } | |||
832 | } | |||
833 | break; | |||
834 | case ICmpInst::ICMP_SLT: | |||
835 | // assume(v <_s c) where c is non-positive | |||
836 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A)))) { | |||
837 | KnownBits RHSKnown = | |||
838 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
839 | ||||
840 | if (RHSKnown.isZero() || RHSKnown.isNegative()) { | |||
841 | // We know that the sign bit is one. | |||
842 | Known.makeNegative(); | |||
843 | } | |||
844 | } | |||
845 | break; | |||
846 | case ICmpInst::ICMP_ULE: | |||
847 | // assume(v <=_u c) | |||
848 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A)))) { | |||
849 | KnownBits RHSKnown = | |||
850 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
851 | ||||
852 | // Whatever high bits in c are zero are known to be zero. | |||
853 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); | |||
854 | } | |||
855 | break; | |||
856 | case ICmpInst::ICMP_ULT: | |||
857 | // assume(v <_u c) | |||
858 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A)))) { | |||
859 | KnownBits RHSKnown = | |||
860 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
861 | ||||
862 | // If the RHS is known zero, then this assumption must be wrong (nothing | |||
863 | // is unsigned less than zero). Signal a conflict and get out of here. | |||
864 | if (RHSKnown.isZero()) { | |||
865 | Known.Zero.setAllBits(); | |||
866 | Known.One.setAllBits(); | |||
867 | break; | |||
868 | } | |||
869 | ||||
870 | // Whatever high bits in c are zero are known to be zero (if c is a power | |||
871 | // of 2, then one more). | |||
872 | if (isKnownToBeAPowerOfTwo(A, false, Depth + 1, QueryNoAC)) | |||
873 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros() + 1); | |||
874 | else | |||
875 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); | |||
876 | } | |||
877 | break; | |||
878 | case ICmpInst::ICMP_NE: { | |||
879 | // assume (v & b != 0) where b is a power of 2 | |||
880 | const APInt *BPow2; | |||
881 | if (match(Cmp, m_ICmp(Pred, m_c_And(m_V, m_Power2(BPow2)), m_Zero()))) { | |||
882 | Known.One |= BPow2->zextOrTrunc(BitWidth); | |||
883 | } | |||
884 | } break; | |||
885 | } | |||
886 | } | |||
887 | ||||
888 | static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known, | |||
889 | unsigned Depth, const Query &Q) { | |||
890 | // Use of assumptions is context-sensitive. If we don't have a context, we | |||
891 | // cannot use them! | |||
892 | if (!Q.AC || !Q.CxtI) | |||
893 | return; | |||
894 | ||||
895 | unsigned BitWidth = Known.getBitWidth(); | |||
896 | ||||
897 | // Refine Known set if the pointer alignment is set by assume bundles. | |||
898 | if (V->getType()->isPointerTy()) { | |||
899 | if (RetainedKnowledge RK = getKnowledgeValidInContext( | |||
900 | V, { Attribute::Alignment }, Q.CxtI, Q.DT, Q.AC)) { | |||
901 | if (isPowerOf2_64(RK.ArgValue)) | |||
902 | Known.Zero.setLowBits(Log2_64(RK.ArgValue)); | |||
903 | } | |||
904 | } | |||
905 | ||||
906 | // Note that the patterns below need to be kept in sync with the code | |||
907 | // in AssumptionCache::updateAffectedValues. | |||
908 | ||||
909 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { | |||
910 | if (!AssumeVH) | |||
911 | continue; | |||
912 | CallInst *I = cast<CallInst>(AssumeVH); | |||
913 | assert(I->getParent()->getParent() == Q.CxtI->getParent()->getParent() &&(static_cast <bool> (I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && "Got assumption for the wrong function!" ) ? void (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 914, __extension__ __PRETTY_FUNCTION__ )) | |||
914 | "Got assumption for the wrong function!")(static_cast <bool> (I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && "Got assumption for the wrong function!" ) ? void (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 914, __extension__ __PRETTY_FUNCTION__ )); | |||
915 | ||||
916 | // Warning: This loop can end up being somewhat performance sensitive. | |||
917 | // We're running this loop for once for each value queried resulting in a | |||
918 | // runtime of ~O(#assumes * #values). | |||
919 | ||||
920 | assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 921, __extension__ __PRETTY_FUNCTION__ )) | |||
921 | "must be an assume intrinsic")(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 921, __extension__ __PRETTY_FUNCTION__ )); | |||
922 | ||||
923 | Value *Arg = I->getArgOperand(0); | |||
924 | ||||
925 | if (Arg == V && isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
926 | assert(BitWidth == 1 && "assume operand is not i1?")(static_cast <bool> (BitWidth == 1 && "assume operand is not i1?" ) ? void (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 926, __extension__ __PRETTY_FUNCTION__ )); | |||
927 | (void)BitWidth; | |||
928 | Known.setAllOnes(); | |||
929 | return; | |||
930 | } | |||
931 | if (match(Arg, m_Not(m_Specific(V))) && | |||
932 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
933 | assert(BitWidth == 1 && "assume operand is not i1?")(static_cast <bool> (BitWidth == 1 && "assume operand is not i1?" ) ? void (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 933, __extension__ __PRETTY_FUNCTION__ )); | |||
934 | (void)BitWidth; | |||
935 | Known.setAllZero(); | |||
936 | return; | |||
937 | } | |||
938 | ||||
939 | // The remaining tests are all recursive, so bail out if we hit the limit. | |||
940 | if (Depth == MaxAnalysisRecursionDepth) | |||
941 | continue; | |||
942 | ||||
943 | ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg); | |||
944 | if (!Cmp) | |||
945 | continue; | |||
946 | ||||
947 | if (!isValidAssumeForContext(I, Q.CxtI, Q.DT)) | |||
948 | continue; | |||
949 | ||||
950 | computeKnownBitsFromCmp(V, Cmp, Known, Depth, Q); | |||
951 | } | |||
952 | ||||
953 | // If assumptions conflict with each other or previous known bits, then we | |||
954 | // have a logical fallacy. It's possible that the assumption is not reachable, | |||
955 | // so this isn't a real bug. On the other hand, the program may have undefined | |||
956 | // behavior, or we might have a bug in the compiler. We can't assert/crash, so | |||
957 | // clear out the known bits, try to warn the user, and hope for the best. | |||
958 | if (Known.Zero.intersects(Known.One)) { | |||
959 | Known.resetAll(); | |||
960 | ||||
961 | if (Q.ORE) | |||
962 | Q.ORE->emit([&]() { | |||
963 | auto *CxtI = const_cast<Instruction *>(Q.CxtI); | |||
964 | return OptimizationRemarkAnalysis("value-tracking", "BadAssumption", | |||
965 | CxtI) | |||
966 | << "Detected conflicting code assumptions. Program may " | |||
967 | "have undefined behavior, or compiler may have " | |||
968 | "internal error."; | |||
969 | }); | |||
970 | } | |||
971 | } | |||
972 | ||||
973 | /// Compute known bits from a shift operator, including those with a | |||
974 | /// non-constant shift amount. Known is the output of this function. Known2 is a | |||
975 | /// pre-allocated temporary with the same bit width as Known and on return | |||
976 | /// contains the known bit of the shift value source. KF is an | |||
977 | /// operator-specific function that, given the known-bits and a shift amount, | |||
978 | /// compute the implied known-bits of the shift operator's result respectively | |||
979 | /// for that shift amount. The results from calling KF are conservatively | |||
980 | /// combined for all permitted shift amounts. | |||
981 | static void computeKnownBitsFromShiftOperator( | |||
982 | const Operator *I, const APInt &DemandedElts, KnownBits &Known, | |||
983 | KnownBits &Known2, unsigned Depth, const Query &Q, | |||
984 | function_ref<KnownBits(const KnownBits &, const KnownBits &)> KF) { | |||
985 | unsigned BitWidth = Known.getBitWidth(); | |||
986 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
987 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
988 | ||||
989 | // Note: We cannot use Known.Zero.getLimitedValue() here, because if | |||
990 | // BitWidth > 64 and any upper bits are known, we'll end up returning the | |||
991 | // limit value (which implies all bits are known). | |||
992 | uint64_t ShiftAmtKZ = Known.Zero.zextOrTrunc(64).getZExtValue(); | |||
993 | uint64_t ShiftAmtKO = Known.One.zextOrTrunc(64).getZExtValue(); | |||
994 | bool ShiftAmtIsConstant = Known.isConstant(); | |||
995 | bool MaxShiftAmtIsOutOfRange = Known.getMaxValue().uge(BitWidth); | |||
996 | ||||
997 | if (ShiftAmtIsConstant) { | |||
998 | Known = KF(Known2, Known); | |||
999 | ||||
1000 | // If the known bits conflict, this must be an overflowing left shift, so | |||
1001 | // the shift result is poison. We can return anything we want. Choose 0 for | |||
1002 | // the best folding opportunity. | |||
1003 | if (Known.hasConflict()) | |||
1004 | Known.setAllZero(); | |||
1005 | ||||
1006 | return; | |||
1007 | } | |||
1008 | ||||
1009 | // If the shift amount could be greater than or equal to the bit-width of the | |||
1010 | // LHS, the value could be poison, but bail out because the check below is | |||
1011 | // expensive. | |||
1012 | // TODO: Should we just carry on? | |||
1013 | if (MaxShiftAmtIsOutOfRange) { | |||
1014 | Known.resetAll(); | |||
1015 | return; | |||
1016 | } | |||
1017 | ||||
1018 | // It would be more-clearly correct to use the two temporaries for this | |||
1019 | // calculation. Reusing the APInts here to prevent unnecessary allocations. | |||
1020 | Known.resetAll(); | |||
1021 | ||||
1022 | // If we know the shifter operand is nonzero, we can sometimes infer more | |||
1023 | // known bits. However this is expensive to compute, so be lazy about it and | |||
1024 | // only compute it when absolutely necessary. | |||
1025 | std::optional<bool> ShifterOperandIsNonZero; | |||
1026 | ||||
1027 | // Early exit if we can't constrain any well-defined shift amount. | |||
1028 | if (!(ShiftAmtKZ & (PowerOf2Ceil(BitWidth) - 1)) && | |||
1029 | !(ShiftAmtKO & (PowerOf2Ceil(BitWidth) - 1))) { | |||
1030 | ShifterOperandIsNonZero = | |||
1031 | isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q); | |||
1032 | if (!*ShifterOperandIsNonZero) | |||
1033 | return; | |||
1034 | } | |||
1035 | ||||
1036 | Known.Zero.setAllBits(); | |||
1037 | Known.One.setAllBits(); | |||
1038 | for (unsigned ShiftAmt = 0; ShiftAmt < BitWidth; ++ShiftAmt) { | |||
1039 | // Combine the shifted known input bits only for those shift amounts | |||
1040 | // compatible with its known constraints. | |||
1041 | if ((ShiftAmt & ~ShiftAmtKZ) != ShiftAmt) | |||
1042 | continue; | |||
1043 | if ((ShiftAmt | ShiftAmtKO) != ShiftAmt) | |||
1044 | continue; | |||
1045 | // If we know the shifter is nonzero, we may be able to infer more known | |||
1046 | // bits. This check is sunk down as far as possible to avoid the expensive | |||
1047 | // call to isKnownNonZero if the cheaper checks above fail. | |||
1048 | if (ShiftAmt == 0) { | |||
1049 | if (!ShifterOperandIsNonZero) | |||
1050 | ShifterOperandIsNonZero = | |||
1051 | isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q); | |||
1052 | if (*ShifterOperandIsNonZero) | |||
1053 | continue; | |||
1054 | } | |||
1055 | ||||
1056 | Known = KnownBits::commonBits( | |||
1057 | Known, KF(Known2, KnownBits::makeConstant(APInt(32, ShiftAmt)))); | |||
1058 | } | |||
1059 | ||||
1060 | // If the known bits conflict, the result is poison. Return a 0 and hope the | |||
1061 | // caller can further optimize that. | |||
1062 | if (Known.hasConflict()) | |||
1063 | Known.setAllZero(); | |||
1064 | } | |||
1065 | ||||
1066 | static KnownBits getKnownBitsFromAndXorOr(const Operator *I, | |||
1067 | const APInt &DemandedElts, | |||
1068 | const KnownBits &KnownLHS, | |||
1069 | const KnownBits &KnownRHS, | |||
1070 | unsigned Depth, const Query &Q) { | |||
1071 | unsigned BitWidth = KnownLHS.getBitWidth(); | |||
1072 | KnownBits KnownOut(BitWidth); | |||
1073 | bool IsAnd = false; | |||
1074 | bool HasKnownOne = !KnownLHS.One.isZero() || !KnownRHS.One.isZero(); | |||
1075 | Value *X = nullptr, *Y = nullptr; | |||
1076 | ||||
1077 | switch (I->getOpcode()) { | |||
1078 | case Instruction::And: | |||
1079 | KnownOut = KnownLHS & KnownRHS; | |||
1080 | IsAnd = true; | |||
1081 | // and(x, -x) is common idioms that will clear all but lowest set | |||
1082 | // bit. If we have a single known bit in x, we can clear all bits | |||
1083 | // above it. | |||
1084 | // TODO: instcombine often reassociates independent `and` which can hide | |||
1085 | // this pattern. Try to match and(x, and(-x, y)) / and(and(x, y), -x). | |||
1086 | if (HasKnownOne && match(I, m_c_And(m_Value(X), m_Neg(m_Deferred(X))))) { | |||
1087 | // -(-x) == x so using whichever (LHS/RHS) gets us a better result. | |||
1088 | if (KnownLHS.countMaxTrailingZeros() <= KnownRHS.countMaxTrailingZeros()) | |||
1089 | KnownOut = KnownLHS.blsi(); | |||
1090 | else | |||
1091 | KnownOut = KnownRHS.blsi(); | |||
1092 | } | |||
1093 | break; | |||
1094 | case Instruction::Or: | |||
1095 | KnownOut = KnownLHS | KnownRHS; | |||
1096 | break; | |||
1097 | case Instruction::Xor: | |||
1098 | KnownOut = KnownLHS ^ KnownRHS; | |||
1099 | // xor(x, x-1) is common idioms that will clear all but lowest set | |||
1100 | // bit. If we have a single known bit in x, we can clear all bits | |||
1101 | // above it. | |||
1102 | // TODO: xor(x, x-1) is often rewritting as xor(x, x-C) where C != | |||
1103 | // -1 but for the purpose of demanded bits (xor(x, x-C) & | |||
1104 | // Demanded) == (xor(x, x-1) & Demanded). Extend the xor pattern | |||
1105 | // to use arbitrary C if xor(x, x-C) as the same as xor(x, x-1). | |||
1106 | if (HasKnownOne && | |||
1107 | match(I, m_c_Xor(m_Value(X), m_c_Add(m_Deferred(X), m_AllOnes())))) { | |||
1108 | const KnownBits &XBits = I->getOperand(0) == X ? KnownLHS : KnownRHS; | |||
1109 | KnownOut = XBits.blsmsk(); | |||
1110 | } | |||
1111 | break; | |||
1112 | default: | |||
1113 | llvm_unreachable("Invalid Op used in 'analyzeKnownBitsFromAndXorOr'")::llvm::llvm_unreachable_internal("Invalid Op used in 'analyzeKnownBitsFromAndXorOr'" , "llvm/lib/Analysis/ValueTracking.cpp", 1113); | |||
1114 | } | |||
1115 | ||||
1116 | // and(x, add (x, -1)) is a common idiom that always clears the low bit; | |||
1117 | // xor/or(x, add (x, -1)) is an idiom that will always set the low bit. | |||
1118 | // here we handle the more general case of adding any odd number by | |||
1119 | // matching the form and/xor/or(x, add(x, y)) where y is odd. | |||
1120 | // TODO: This could be generalized to clearing any bit set in y where the | |||
1121 | // following bit is known to be unset in y. | |||
1122 | if (!KnownOut.Zero[0] && !KnownOut.One[0] && | |||
1123 | (match(I, m_c_BinOp(m_Value(X), m_c_Add(m_Deferred(X), m_Value(Y)))) || | |||
1124 | match(I, m_c_BinOp(m_Value(X), m_Sub(m_Deferred(X), m_Value(Y)))) || | |||
1125 | match(I, m_c_BinOp(m_Value(X), m_Sub(m_Value(Y), m_Deferred(X)))))) { | |||
1126 | KnownBits KnownY(BitWidth); | |||
1127 | computeKnownBits(Y, DemandedElts, KnownY, Depth + 1, Q); | |||
1128 | if (KnownY.countMinTrailingOnes() > 0) { | |||
1129 | if (IsAnd) | |||
1130 | KnownOut.Zero.setBit(0); | |||
1131 | else | |||
1132 | KnownOut.One.setBit(0); | |||
1133 | } | |||
1134 | } | |||
1135 | return KnownOut; | |||
1136 | } | |||
1137 | ||||
1138 | // Public so this can be used in `SimplifyDemandedUseBits`. | |||
1139 | KnownBits llvm::analyzeKnownBitsFromAndXorOr( | |||
1140 | const Operator *I, const KnownBits &KnownLHS, const KnownBits &KnownRHS, | |||
1141 | unsigned Depth, const DataLayout &DL, AssumptionCache *AC, | |||
1142 | const Instruction *CxtI, const DominatorTree *DT, | |||
1143 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
1144 | auto *FVTy = dyn_cast<FixedVectorType>(I->getType()); | |||
1145 | APInt DemandedElts = | |||
1146 | FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1); | |||
1147 | ||||
1148 | return getKnownBitsFromAndXorOr( | |||
1149 | I, DemandedElts, KnownLHS, KnownRHS, Depth, | |||
1150 | Query(DL, AC, safeCxtI(I, CxtI), DT, UseInstrInfo, ORE)); | |||
1151 | } | |||
1152 | ||||
1153 | ConstantRange llvm::getVScaleRange(const Function *F, unsigned BitWidth) { | |||
1154 | Attribute Attr = F->getFnAttribute(Attribute::VScaleRange); | |||
1155 | // Without vscale_range, we only know that vscale is non-zero. | |||
1156 | if (!Attr.isValid()) | |||
1157 | return ConstantRange(APInt(BitWidth, 1), APInt::getZero(BitWidth)); | |||
1158 | ||||
1159 | unsigned AttrMin = Attr.getVScaleRangeMin(); | |||
1160 | // Minimum is larger than vscale width, result is always poison. | |||
1161 | if ((unsigned)llvm::bit_width(AttrMin) > BitWidth) | |||
1162 | return ConstantRange::getEmpty(BitWidth); | |||
1163 | ||||
1164 | APInt Min(BitWidth, AttrMin); | |||
1165 | std::optional<unsigned> AttrMax = Attr.getVScaleRangeMax(); | |||
1166 | if (!AttrMax || (unsigned)llvm::bit_width(*AttrMax) > BitWidth) | |||
1167 | return ConstantRange(Min, APInt::getZero(BitWidth)); | |||
1168 | ||||
1169 | return ConstantRange(Min, APInt(BitWidth, *AttrMax) + 1); | |||
1170 | } | |||
1171 | ||||
1172 | static void computeKnownBitsFromOperator(const Operator *I, | |||
1173 | const APInt &DemandedElts, | |||
1174 | KnownBits &Known, unsigned Depth, | |||
1175 | const Query &Q) { | |||
1176 | unsigned BitWidth = Known.getBitWidth(); | |||
1177 | ||||
1178 | KnownBits Known2(BitWidth); | |||
1179 | switch (I->getOpcode()) { | |||
1180 | default: break; | |||
1181 | case Instruction::Load: | |||
1182 | if (MDNode *MD = | |||
1183 | Q.IIQ.getMetadata(cast<LoadInst>(I), LLVMContext::MD_range)) | |||
1184 | computeKnownBitsFromRangeMetadata(*MD, Known); | |||
1185 | break; | |||
1186 | case Instruction::And: | |||
1187 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
1188 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1189 | ||||
1190 | Known = getKnownBitsFromAndXorOr(I, DemandedElts, Known2, Known, Depth, Q); | |||
1191 | break; | |||
1192 | case Instruction::Or: | |||
1193 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
1194 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1195 | ||||
1196 | Known = getKnownBitsFromAndXorOr(I, DemandedElts, Known2, Known, Depth, Q); | |||
1197 | break; | |||
1198 | case Instruction::Xor: | |||
1199 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
1200 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1201 | ||||
1202 | Known = getKnownBitsFromAndXorOr(I, DemandedElts, Known2, Known, Depth, Q); | |||
1203 | break; | |||
1204 | case Instruction::Mul: { | |||
1205 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1206 | computeKnownBitsMul(I->getOperand(0), I->getOperand(1), NSW, DemandedElts, | |||
1207 | Known, Known2, Depth, Q); | |||
1208 | break; | |||
1209 | } | |||
1210 | case Instruction::UDiv: { | |||
1211 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1212 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1213 | Known = KnownBits::udiv(Known, Known2); | |||
1214 | break; | |||
1215 | } | |||
1216 | case Instruction::Select: { | |||
1217 | const Value *LHS = nullptr, *RHS = nullptr; | |||
1218 | SelectPatternFlavor SPF = matchSelectPattern(I, LHS, RHS).Flavor; | |||
1219 | if (SelectPatternResult::isMinOrMax(SPF)) { | |||
1220 | computeKnownBits(RHS, Known, Depth + 1, Q); | |||
1221 | computeKnownBits(LHS, Known2, Depth + 1, Q); | |||
1222 | switch (SPF) { | |||
1223 | default: | |||
1224 | llvm_unreachable("Unhandled select pattern flavor!")::llvm::llvm_unreachable_internal("Unhandled select pattern flavor!" , "llvm/lib/Analysis/ValueTracking.cpp", 1224); | |||
1225 | case SPF_SMAX: | |||
1226 | Known = KnownBits::smax(Known, Known2); | |||
1227 | break; | |||
1228 | case SPF_SMIN: | |||
1229 | Known = KnownBits::smin(Known, Known2); | |||
1230 | break; | |||
1231 | case SPF_UMAX: | |||
1232 | Known = KnownBits::umax(Known, Known2); | |||
1233 | break; | |||
1234 | case SPF_UMIN: | |||
1235 | Known = KnownBits::umin(Known, Known2); | |||
1236 | break; | |||
1237 | } | |||
1238 | break; | |||
1239 | } | |||
1240 | ||||
1241 | computeKnownBits(I->getOperand(2), Known, Depth + 1, Q); | |||
1242 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1243 | ||||
1244 | // Only known if known in both the LHS and RHS. | |||
1245 | Known = KnownBits::commonBits(Known, Known2); | |||
1246 | ||||
1247 | if (SPF == SPF_ABS) { | |||
1248 | // RHS from matchSelectPattern returns the negation part of abs pattern. | |||
1249 | // If the negate has an NSW flag we can assume the sign bit of the result | |||
1250 | // will be 0 because that makes abs(INT_MIN) undefined. | |||
1251 | if (match(RHS, m_Neg(m_Specific(LHS))) && | |||
1252 | Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RHS))) | |||
1253 | Known.Zero.setSignBit(); | |||
1254 | } | |||
1255 | ||||
1256 | break; | |||
1257 | } | |||
1258 | case Instruction::FPTrunc: | |||
1259 | case Instruction::FPExt: | |||
1260 | case Instruction::FPToUI: | |||
1261 | case Instruction::FPToSI: | |||
1262 | case Instruction::SIToFP: | |||
1263 | case Instruction::UIToFP: | |||
1264 | break; // Can't work with floating point. | |||
1265 | case Instruction::PtrToInt: | |||
1266 | case Instruction::IntToPtr: | |||
1267 | // Fall through and handle them the same as zext/trunc. | |||
1268 | [[fallthrough]]; | |||
1269 | case Instruction::ZExt: | |||
1270 | case Instruction::Trunc: { | |||
1271 | Type *SrcTy = I->getOperand(0)->getType(); | |||
1272 | ||||
1273 | unsigned SrcBitWidth; | |||
1274 | // Note that we handle pointer operands here because of inttoptr/ptrtoint | |||
1275 | // which fall through here. | |||
1276 | Type *ScalarTy = SrcTy->getScalarType(); | |||
1277 | SrcBitWidth = ScalarTy->isPointerTy() ? | |||
1278 | Q.DL.getPointerTypeSizeInBits(ScalarTy) : | |||
1279 | Q.DL.getTypeSizeInBits(ScalarTy); | |||
1280 | ||||
1281 | assert(SrcBitWidth && "SrcBitWidth can't be zero")(static_cast <bool> (SrcBitWidth && "SrcBitWidth can't be zero" ) ? void (0) : __assert_fail ("SrcBitWidth && \"SrcBitWidth can't be zero\"" , "llvm/lib/Analysis/ValueTracking.cpp", 1281, __extension__ __PRETTY_FUNCTION__ )); | |||
1282 | Known = Known.anyextOrTrunc(SrcBitWidth); | |||
1283 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1284 | Known = Known.zextOrTrunc(BitWidth); | |||
1285 | break; | |||
1286 | } | |||
1287 | case Instruction::BitCast: { | |||
1288 | Type *SrcTy = I->getOperand(0)->getType(); | |||
1289 | if (SrcTy->isIntOrPtrTy() && | |||
1290 | // TODO: For now, not handling conversions like: | |||
1291 | // (bitcast i64 %x to <2 x i32>) | |||
1292 | !I->getType()->isVectorTy()) { | |||
1293 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1294 | break; | |||
1295 | } | |||
1296 | ||||
1297 | // Handle cast from vector integer type to scalar or vector integer. | |||
1298 | auto *SrcVecTy = dyn_cast<FixedVectorType>(SrcTy); | |||
1299 | if (!SrcVecTy || !SrcVecTy->getElementType()->isIntegerTy() || | |||
1300 | !I->getType()->isIntOrIntVectorTy() || | |||
1301 | isa<ScalableVectorType>(I->getType())) | |||
1302 | break; | |||
1303 | ||||
1304 | // Look through a cast from narrow vector elements to wider type. | |||
1305 | // Examples: v4i32 -> v2i64, v3i8 -> v24 | |||
1306 | unsigned SubBitWidth = SrcVecTy->getScalarSizeInBits(); | |||
1307 | if (BitWidth % SubBitWidth == 0) { | |||
1308 | // Known bits are automatically intersected across demanded elements of a | |||
1309 | // vector. So for example, if a bit is computed as known zero, it must be | |||
1310 | // zero across all demanded elements of the vector. | |||
1311 | // | |||
1312 | // For this bitcast, each demanded element of the output is sub-divided | |||
1313 | // across a set of smaller vector elements in the source vector. To get | |||
1314 | // the known bits for an entire element of the output, compute the known | |||
1315 | // bits for each sub-element sequentially. This is done by shifting the | |||
1316 | // one-set-bit demanded elements parameter across the sub-elements for | |||
1317 | // consecutive calls to computeKnownBits. We are using the demanded | |||
1318 | // elements parameter as a mask operator. | |||
1319 | // | |||
1320 | // The known bits of each sub-element are then inserted into place | |||
1321 | // (dependent on endian) to form the full result of known bits. | |||
1322 | unsigned NumElts = DemandedElts.getBitWidth(); | |||
1323 | unsigned SubScale = BitWidth / SubBitWidth; | |||
1324 | APInt SubDemandedElts = APInt::getZero(NumElts * SubScale); | |||
1325 | for (unsigned i = 0; i != NumElts; ++i) { | |||
1326 | if (DemandedElts[i]) | |||
1327 | SubDemandedElts.setBit(i * SubScale); | |||
1328 | } | |||
1329 | ||||
1330 | KnownBits KnownSrc(SubBitWidth); | |||
1331 | for (unsigned i = 0; i != SubScale; ++i) { | |||
1332 | computeKnownBits(I->getOperand(0), SubDemandedElts.shl(i), KnownSrc, | |||
1333 | Depth + 1, Q); | |||
1334 | unsigned ShiftElt = Q.DL.isLittleEndian() ? i : SubScale - 1 - i; | |||
1335 | Known.insertBits(KnownSrc, ShiftElt * SubBitWidth); | |||
1336 | } | |||
1337 | } | |||
1338 | break; | |||
1339 | } | |||
1340 | case Instruction::SExt: { | |||
1341 | // Compute the bits in the result that are not present in the input. | |||
1342 | unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits(); | |||
1343 | ||||
1344 | Known = Known.trunc(SrcBitWidth); | |||
1345 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1346 | // If the sign bit of the input is known set or clear, then we know the | |||
1347 | // top bits of the result. | |||
1348 | Known = Known.sext(BitWidth); | |||
1349 | break; | |||
1350 | } | |||
1351 | case Instruction::Shl: { | |||
1352 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1353 | auto KF = [NSW](const KnownBits &KnownVal, const KnownBits &KnownAmt) { | |||
1354 | KnownBits Result = KnownBits::shl(KnownVal, KnownAmt); | |||
1355 | // If this shift has "nsw" keyword, then the result is either a poison | |||
1356 | // value or has the same sign bit as the first operand. | |||
1357 | if (NSW) { | |||
1358 | if (KnownVal.Zero.isSignBitSet()) | |||
1359 | Result.Zero.setSignBit(); | |||
1360 | if (KnownVal.One.isSignBitSet()) | |||
1361 | Result.One.setSignBit(); | |||
1362 | } | |||
1363 | return Result; | |||
1364 | }; | |||
1365 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, | |||
1366 | KF); | |||
1367 | // Trailing zeros of a right-shifted constant never decrease. | |||
1368 | const APInt *C; | |||
1369 | if (match(I->getOperand(0), m_APInt(C))) | |||
1370 | Known.Zero.setLowBits(C->countr_zero()); | |||
1371 | break; | |||
1372 | } | |||
1373 | case Instruction::LShr: { | |||
1374 | auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) { | |||
1375 | return KnownBits::lshr(KnownVal, KnownAmt); | |||
1376 | }; | |||
1377 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, | |||
1378 | KF); | |||
1379 | // Leading zeros of a left-shifted constant never decrease. | |||
1380 | const APInt *C; | |||
1381 | if (match(I->getOperand(0), m_APInt(C))) | |||
1382 | Known.Zero.setHighBits(C->countl_zero()); | |||
1383 | break; | |||
1384 | } | |||
1385 | case Instruction::AShr: { | |||
1386 | auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) { | |||
1387 | return KnownBits::ashr(KnownVal, KnownAmt); | |||
1388 | }; | |||
1389 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, | |||
1390 | KF); | |||
1391 | break; | |||
1392 | } | |||
1393 | case Instruction::Sub: { | |||
1394 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1395 | computeKnownBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW, | |||
1396 | DemandedElts, Known, Known2, Depth, Q); | |||
1397 | break; | |||
1398 | } | |||
1399 | case Instruction::Add: { | |||
1400 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1401 | computeKnownBitsAddSub(true, I->getOperand(0), I->getOperand(1), NSW, | |||
1402 | DemandedElts, Known, Known2, Depth, Q); | |||
1403 | break; | |||
1404 | } | |||
1405 | case Instruction::SRem: | |||
1406 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1407 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1408 | Known = KnownBits::srem(Known, Known2); | |||
1409 | break; | |||
1410 | ||||
1411 | case Instruction::URem: | |||
1412 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1413 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1414 | Known = KnownBits::urem(Known, Known2); | |||
1415 | break; | |||
1416 | case Instruction::Alloca: | |||
1417 | Known.Zero.setLowBits(Log2(cast<AllocaInst>(I)->getAlign())); | |||
1418 | break; | |||
1419 | case Instruction::GetElementPtr: { | |||
1420 | // Analyze all of the subscripts of this getelementptr instruction | |||
1421 | // to determine if we can prove known low zero bits. | |||
1422 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1423 | // Accumulate the constant indices in a separate variable | |||
1424 | // to minimize the number of calls to computeForAddSub. | |||
1425 | APInt AccConstIndices(BitWidth, 0, /*IsSigned*/ true); | |||
1426 | ||||
1427 | gep_type_iterator GTI = gep_type_begin(I); | |||
1428 | for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) { | |||
1429 | // TrailZ can only become smaller, short-circuit if we hit zero. | |||
1430 | if (Known.isUnknown()) | |||
1431 | break; | |||
1432 | ||||
1433 | Value *Index = I->getOperand(i); | |||
1434 | ||||
1435 | // Handle case when index is zero. | |||
1436 | Constant *CIndex = dyn_cast<Constant>(Index); | |||
1437 | if (CIndex && CIndex->isZeroValue()) | |||
1438 | continue; | |||
1439 | ||||
1440 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
1441 | // Handle struct member offset arithmetic. | |||
1442 | ||||
1443 | assert(CIndex &&(static_cast <bool> (CIndex && "Access to structure field must be known at compile time" ) ? void (0) : __assert_fail ("CIndex && \"Access to structure field must be known at compile time\"" , "llvm/lib/Analysis/ValueTracking.cpp", 1444, __extension__ __PRETTY_FUNCTION__ )) | |||
1444 | "Access to structure field must be known at compile time")(static_cast <bool> (CIndex && "Access to structure field must be known at compile time" ) ? void (0) : __assert_fail ("CIndex && \"Access to structure field must be known at compile time\"" , "llvm/lib/Analysis/ValueTracking.cpp", 1444, __extension__ __PRETTY_FUNCTION__ )); | |||
1445 | ||||
1446 | if (CIndex->getType()->isVectorTy()) | |||
1447 | Index = CIndex->getSplatValue(); | |||
1448 | ||||
1449 | unsigned Idx = cast<ConstantInt>(Index)->getZExtValue(); | |||
1450 | const StructLayout *SL = Q.DL.getStructLayout(STy); | |||
1451 | uint64_t Offset = SL->getElementOffset(Idx); | |||
1452 | AccConstIndices += Offset; | |||
1453 | continue; | |||
1454 | } | |||
1455 | ||||
1456 | // Handle array index arithmetic. | |||
1457 | Type *IndexedTy = GTI.getIndexedType(); | |||
1458 | if (!IndexedTy->isSized()) { | |||
1459 | Known.resetAll(); | |||
1460 | break; | |||
1461 | } | |||
1462 | ||||
1463 | unsigned IndexBitWidth = Index->getType()->getScalarSizeInBits(); | |||
1464 | KnownBits IndexBits(IndexBitWidth); | |||
1465 | computeKnownBits(Index, IndexBits, Depth + 1, Q); | |||
1466 | TypeSize IndexTypeSize = Q.DL.getTypeAllocSize(IndexedTy); | |||
1467 | uint64_t TypeSizeInBytes = IndexTypeSize.getKnownMinValue(); | |||
1468 | KnownBits ScalingFactor(IndexBitWidth); | |||
1469 | // Multiply by current sizeof type. | |||
1470 | // &A[i] == A + i * sizeof(*A[i]). | |||
1471 | if (IndexTypeSize.isScalable()) { | |||
1472 | // For scalable types the only thing we know about sizeof is | |||
1473 | // that this is a multiple of the minimum size. | |||
1474 | ScalingFactor.Zero.setLowBits(llvm::countr_zero(TypeSizeInBytes)); | |||
1475 | } else if (IndexBits.isConstant()) { | |||
1476 | APInt IndexConst = IndexBits.getConstant(); | |||
1477 | APInt ScalingFactor(IndexBitWidth, TypeSizeInBytes); | |||
1478 | IndexConst *= ScalingFactor; | |||
1479 | AccConstIndices += IndexConst.sextOrTrunc(BitWidth); | |||
1480 | continue; | |||
1481 | } else { | |||
1482 | ScalingFactor = | |||
1483 | KnownBits::makeConstant(APInt(IndexBitWidth, TypeSizeInBytes)); | |||
1484 | } | |||
1485 | IndexBits = KnownBits::mul(IndexBits, ScalingFactor); | |||
1486 | ||||
1487 | // If the offsets have a different width from the pointer, according | |||
1488 | // to the language reference we need to sign-extend or truncate them | |||
1489 | // to the width of the pointer. | |||
1490 | IndexBits = IndexBits.sextOrTrunc(BitWidth); | |||
1491 | ||||
1492 | // Note that inbounds does *not* guarantee nsw for the addition, as only | |||
1493 | // the offset is signed, while the base address is unsigned. | |||
1494 | Known = KnownBits::computeForAddSub( | |||
1495 | /*Add=*/true, /*NSW=*/false, Known, IndexBits); | |||
1496 | } | |||
1497 | if (!Known.isUnknown() && !AccConstIndices.isZero()) { | |||
1498 | KnownBits Index = KnownBits::makeConstant(AccConstIndices); | |||
1499 | Known = KnownBits::computeForAddSub( | |||
1500 | /*Add=*/true, /*NSW=*/false, Known, Index); | |||
1501 | } | |||
1502 | break; | |||
1503 | } | |||
1504 | case Instruction::PHI: { | |||
1505 | const PHINode *P = cast<PHINode>(I); | |||
1506 | BinaryOperator *BO = nullptr; | |||
1507 | Value *R = nullptr, *L = nullptr; | |||
1508 | if (matchSimpleRecurrence(P, BO, R, L)) { | |||
1509 | // Handle the case of a simple two-predecessor recurrence PHI. | |||
1510 | // There's a lot more that could theoretically be done here, but | |||
1511 | // this is sufficient to catch some interesting cases. | |||
1512 | unsigned Opcode = BO->getOpcode(); | |||
1513 | ||||
1514 | // If this is a shift recurrence, we know the bits being shifted in. | |||
1515 | // We can combine that with information about the start value of the | |||
1516 | // recurrence to conclude facts about the result. | |||
1517 | if ((Opcode == Instruction::LShr || Opcode == Instruction::AShr || | |||
1518 | Opcode == Instruction::Shl) && | |||
1519 | BO->getOperand(0) == I) { | |||
1520 | ||||
1521 | // We have matched a recurrence of the form: | |||
1522 | // %iv = [R, %entry], [%iv.next, %backedge] | |||
1523 | // %iv.next = shift_op %iv, L | |||
1524 | ||||
1525 | // Recurse with the phi context to avoid concern about whether facts | |||
1526 | // inferred hold at original context instruction. TODO: It may be | |||
1527 | // correct to use the original context. IF warranted, explore and | |||
1528 | // add sufficient tests to cover. | |||
1529 | Query RecQ = Q; | |||
1530 | RecQ.CxtI = P; | |||
1531 | computeKnownBits(R, DemandedElts, Known2, Depth + 1, RecQ); | |||
1532 | switch (Opcode) { | |||
1533 | case Instruction::Shl: | |||
1534 | // A shl recurrence will only increase the tailing zeros | |||
1535 | Known.Zero.setLowBits(Known2.countMinTrailingZeros()); | |||
1536 | break; | |||
1537 | case Instruction::LShr: | |||
1538 | // A lshr recurrence will preserve the leading zeros of the | |||
1539 | // start value | |||
1540 | Known.Zero.setHighBits(Known2.countMinLeadingZeros()); | |||
1541 | break; | |||
1542 | case Instruction::AShr: | |||
1543 | // An ashr recurrence will extend the initial sign bit | |||
1544 | Known.Zero.setHighBits(Known2.countMinLeadingZeros()); | |||
1545 | Known.One.setHighBits(Known2.countMinLeadingOnes()); | |||
1546 | break; | |||
1547 | }; | |||
1548 | } | |||
1549 | ||||
1550 | // Check for operations that have the property that if | |||
1551 | // both their operands have low zero bits, the result | |||
1552 | // will have low zero bits. | |||
1553 | if (Opcode == Instruction::Add || | |||
1554 | Opcode == Instruction::Sub || | |||
1555 | Opcode == Instruction::And || | |||
1556 | Opcode == Instruction::Or || | |||
1557 | Opcode == Instruction::Mul) { | |||
1558 | // Change the context instruction to the "edge" that flows into the | |||
1559 | // phi. This is important because that is where the value is actually | |||
1560 | // "evaluated" even though it is used later somewhere else. (see also | |||
1561 | // D69571). | |||
1562 | Query RecQ = Q; | |||
1563 | ||||
1564 | unsigned OpNum = P->getOperand(0) == R ? 0 : 1; | |||
1565 | Instruction *RInst = P->getIncomingBlock(OpNum)->getTerminator(); | |||
1566 | Instruction *LInst = P->getIncomingBlock(1-OpNum)->getTerminator(); | |||
1567 | ||||
1568 | // Ok, we have a PHI of the form L op= R. Check for low | |||
1569 | // zero bits. | |||
1570 | RecQ.CxtI = RInst; | |||
1571 | computeKnownBits(R, Known2, Depth + 1, RecQ); | |||
1572 | ||||
1573 | // We need to take the minimum number of known bits | |||
1574 | KnownBits Known3(BitWidth); | |||
1575 | RecQ.CxtI = LInst; | |||
1576 | computeKnownBits(L, Known3, Depth + 1, RecQ); | |||
1577 | ||||
1578 | Known.Zero.setLowBits(std::min(Known2.countMinTrailingZeros(), | |||
1579 | Known3.countMinTrailingZeros())); | |||
1580 | ||||
1581 | auto *OverflowOp = dyn_cast<OverflowingBinaryOperator>(BO); | |||
1582 | if (OverflowOp && Q.IIQ.hasNoSignedWrap(OverflowOp)) { | |||
1583 | // If initial value of recurrence is nonnegative, and we are adding | |||
1584 | // a nonnegative number with nsw, the result can only be nonnegative | |||
1585 | // or poison value regardless of the number of times we execute the | |||
1586 | // add in phi recurrence. If initial value is negative and we are | |||
1587 | // adding a negative number with nsw, the result can only be | |||
1588 | // negative or poison value. Similar arguments apply to sub and mul. | |||
1589 | // | |||
1590 | // (add non-negative, non-negative) --> non-negative | |||
1591 | // (add negative, negative) --> negative | |||
1592 | if (Opcode == Instruction::Add) { | |||
1593 | if (Known2.isNonNegative() && Known3.isNonNegative()) | |||
1594 | Known.makeNonNegative(); | |||
1595 | else if (Known2.isNegative() && Known3.isNegative()) | |||
1596 | Known.makeNegative(); | |||
1597 | } | |||
1598 | ||||
1599 | // (sub nsw non-negative, negative) --> non-negative | |||
1600 | // (sub nsw negative, non-negative) --> negative | |||
1601 | else if (Opcode == Instruction::Sub && BO->getOperand(0) == I) { | |||
1602 | if (Known2.isNonNegative() && Known3.isNegative()) | |||
1603 | Known.makeNonNegative(); | |||
1604 | else if (Known2.isNegative() && Known3.isNonNegative()) | |||
1605 | Known.makeNegative(); | |||
1606 | } | |||
1607 | ||||
1608 | // (mul nsw non-negative, non-negative) --> non-negative | |||
1609 | else if (Opcode == Instruction::Mul && Known2.isNonNegative() && | |||
1610 | Known3.isNonNegative()) | |||
1611 | Known.makeNonNegative(); | |||
1612 | } | |||
1613 | ||||
1614 | break; | |||
1615 | } | |||
1616 | } | |||
1617 | ||||
1618 | // Unreachable blocks may have zero-operand PHI nodes. | |||
1619 | if (P->getNumIncomingValues() == 0) | |||
1620 | break; | |||
1621 | ||||
1622 | // Otherwise take the unions of the known bit sets of the operands, | |||
1623 | // taking conservative care to avoid excessive recursion. | |||
1624 | if (Depth < MaxAnalysisRecursionDepth - 1 && !Known.Zero && !Known.One) { | |||
1625 | // Skip if every incoming value references to ourself. | |||
1626 | if (isa_and_nonnull<UndefValue>(P->hasConstantValue())) | |||
1627 | break; | |||
1628 | ||||
1629 | Known.Zero.setAllBits(); | |||
1630 | Known.One.setAllBits(); | |||
1631 | for (unsigned u = 0, e = P->getNumIncomingValues(); u < e; ++u) { | |||
1632 | Value *IncValue = P->getIncomingValue(u); | |||
1633 | // Skip direct self references. | |||
1634 | if (IncValue == P) continue; | |||
1635 | ||||
1636 | // Change the context instruction to the "edge" that flows into the | |||
1637 | // phi. This is important because that is where the value is actually | |||
1638 | // "evaluated" even though it is used later somewhere else. (see also | |||
1639 | // D69571). | |||
1640 | Query RecQ = Q; | |||
1641 | RecQ.CxtI = P->getIncomingBlock(u)->getTerminator(); | |||
1642 | ||||
1643 | Known2 = KnownBits(BitWidth); | |||
1644 | ||||
1645 | // Recurse, but cap the recursion to one level, because we don't | |||
1646 | // want to waste time spinning around in loops. | |||
1647 | computeKnownBits(IncValue, Known2, MaxAnalysisRecursionDepth - 1, RecQ); | |||
1648 | ||||
1649 | // If this failed, see if we can use a conditional branch into the phi | |||
1650 | // to help us determine the range of the value. | |||
1651 | if (Known2.isUnknown()) { | |||
1652 | ICmpInst::Predicate Pred; | |||
1653 | const APInt *RHSC; | |||
1654 | BasicBlock *TrueSucc, *FalseSucc; | |||
1655 | // TODO: Use RHS Value and compute range from its known bits. | |||
1656 | if (match(RecQ.CxtI, | |||
1657 | m_Br(m_c_ICmp(Pred, m_Specific(IncValue), m_APInt(RHSC)), | |||
1658 | m_BasicBlock(TrueSucc), m_BasicBlock(FalseSucc)))) { | |||
1659 | // Check for cases of duplicate successors. | |||
1660 | if ((TrueSucc == P->getParent()) != (FalseSucc == P->getParent())) { | |||
1661 | // If we're using the false successor, invert the predicate. | |||
1662 | if (FalseSucc == P->getParent()) | |||
1663 | Pred = CmpInst::getInversePredicate(Pred); | |||
1664 | ||||
1665 | switch (Pred) { | |||
1666 | case CmpInst::Predicate::ICMP_EQ: | |||
1667 | Known2 = KnownBits::makeConstant(*RHSC); | |||
1668 | break; | |||
1669 | case CmpInst::Predicate::ICMP_ULE: | |||
1670 | Known2.Zero.setHighBits(RHSC->countl_zero()); | |||
1671 | break; | |||
1672 | case CmpInst::Predicate::ICMP_ULT: | |||
1673 | Known2.Zero.setHighBits((*RHSC - 1).countl_zero()); | |||
1674 | break; | |||
1675 | default: | |||
1676 | // TODO - add additional integer predicate handling. | |||
1677 | break; | |||
1678 | } | |||
1679 | } | |||
1680 | } | |||
1681 | } | |||
1682 | ||||
1683 | Known = KnownBits::commonBits(Known, Known2); | |||
1684 | // If all bits have been ruled out, there's no need to check | |||
1685 | // more operands. | |||
1686 | if (Known.isUnknown()) | |||
1687 | break; | |||
1688 | } | |||
1689 | } | |||
1690 | break; | |||
1691 | } | |||
1692 | case Instruction::Call: | |||
1693 | case Instruction::Invoke: | |||
1694 | // If range metadata is attached to this call, set known bits from that, | |||
1695 | // and then intersect with known bits based on other properties of the | |||
1696 | // function. | |||
1697 | if (MDNode *MD = | |||
1698 | Q.IIQ.getMetadata(cast<Instruction>(I), LLVMContext::MD_range)) | |||
1699 | computeKnownBitsFromRangeMetadata(*MD, Known); | |||
1700 | if (const Value *RV = cast<CallBase>(I)->getReturnedArgOperand()) { | |||
1701 | computeKnownBits(RV, Known2, Depth + 1, Q); | |||
1702 | Known.Zero |= Known2.Zero; | |||
1703 | Known.One |= Known2.One; | |||
1704 | } | |||
1705 | if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { | |||
1706 | switch (II->getIntrinsicID()) { | |||
1707 | default: break; | |||
1708 | case Intrinsic::abs: { | |||
1709 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1710 | bool IntMinIsPoison = match(II->getArgOperand(1), m_One()); | |||
1711 | Known = Known2.abs(IntMinIsPoison); | |||
1712 | break; | |||
1713 | } | |||
1714 | case Intrinsic::bitreverse: | |||
1715 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1716 | Known.Zero |= Known2.Zero.reverseBits(); | |||
1717 | Known.One |= Known2.One.reverseBits(); | |||
1718 | break; | |||
1719 | case Intrinsic::bswap: | |||
1720 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1721 | Known.Zero |= Known2.Zero.byteSwap(); | |||
1722 | Known.One |= Known2.One.byteSwap(); | |||
1723 | break; | |||
1724 | case Intrinsic::ctlz: { | |||
1725 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1726 | // If we have a known 1, its position is our upper bound. | |||
1727 | unsigned PossibleLZ = Known2.countMaxLeadingZeros(); | |||
1728 | // If this call is poison for 0 input, the result will be less than 2^n. | |||
1729 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) | |||
1730 | PossibleLZ = std::min(PossibleLZ, BitWidth - 1); | |||
1731 | unsigned LowBits = llvm::bit_width(PossibleLZ); | |||
1732 | Known.Zero.setBitsFrom(LowBits); | |||
1733 | break; | |||
1734 | } | |||
1735 | case Intrinsic::cttz: { | |||
1736 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1737 | // If we have a known 1, its position is our upper bound. | |||
1738 | unsigned PossibleTZ = Known2.countMaxTrailingZeros(); | |||
1739 | // If this call is poison for 0 input, the result will be less than 2^n. | |||
1740 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) | |||
1741 | PossibleTZ = std::min(PossibleTZ, BitWidth - 1); | |||
1742 | unsigned LowBits = llvm::bit_width(PossibleTZ); | |||
1743 | Known.Zero.setBitsFrom(LowBits); | |||
1744 | break; | |||
1745 | } | |||
1746 | case Intrinsic::ctpop: { | |||
1747 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1748 | // We can bound the space the count needs. Also, bits known to be zero | |||
1749 | // can't contribute to the population. | |||
1750 | unsigned BitsPossiblySet = Known2.countMaxPopulation(); | |||
1751 | unsigned LowBits = llvm::bit_width(BitsPossiblySet); | |||
1752 | Known.Zero.setBitsFrom(LowBits); | |||
1753 | // TODO: we could bound KnownOne using the lower bound on the number | |||
1754 | // of bits which might be set provided by popcnt KnownOne2. | |||
1755 | break; | |||
1756 | } | |||
1757 | case Intrinsic::fshr: | |||
1758 | case Intrinsic::fshl: { | |||
1759 | const APInt *SA; | |||
1760 | if (!match(I->getOperand(2), m_APInt(SA))) | |||
1761 | break; | |||
1762 | ||||
1763 | // Normalize to funnel shift left. | |||
1764 | uint64_t ShiftAmt = SA->urem(BitWidth); | |||
1765 | if (II->getIntrinsicID() == Intrinsic::fshr) | |||
1766 | ShiftAmt = BitWidth - ShiftAmt; | |||
1767 | ||||
1768 | KnownBits Known3(BitWidth); | |||
1769 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1770 | computeKnownBits(I->getOperand(1), Known3, Depth + 1, Q); | |||
1771 | ||||
1772 | Known.Zero = | |||
1773 | Known2.Zero.shl(ShiftAmt) | Known3.Zero.lshr(BitWidth - ShiftAmt); | |||
1774 | Known.One = | |||
1775 | Known2.One.shl(ShiftAmt) | Known3.One.lshr(BitWidth - ShiftAmt); | |||
1776 | break; | |||
1777 | } | |||
1778 | case Intrinsic::uadd_sat: | |||
1779 | case Intrinsic::usub_sat: { | |||
1780 | bool IsAdd = II->getIntrinsicID() == Intrinsic::uadd_sat; | |||
1781 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1782 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1783 | ||||
1784 | // Add: Leading ones of either operand are preserved. | |||
1785 | // Sub: Leading zeros of LHS and leading ones of RHS are preserved | |||
1786 | // as leading zeros in the result. | |||
1787 | unsigned LeadingKnown; | |||
1788 | if (IsAdd) | |||
1789 | LeadingKnown = std::max(Known.countMinLeadingOnes(), | |||
1790 | Known2.countMinLeadingOnes()); | |||
1791 | else | |||
1792 | LeadingKnown = std::max(Known.countMinLeadingZeros(), | |||
1793 | Known2.countMinLeadingOnes()); | |||
1794 | ||||
1795 | Known = KnownBits::computeForAddSub( | |||
1796 | IsAdd, /* NSW */ false, Known, Known2); | |||
1797 | ||||
1798 | // We select between the operation result and all-ones/zero | |||
1799 | // respectively, so we can preserve known ones/zeros. | |||
1800 | if (IsAdd) { | |||
1801 | Known.One.setHighBits(LeadingKnown); | |||
1802 | Known.Zero.clearAllBits(); | |||
1803 | } else { | |||
1804 | Known.Zero.setHighBits(LeadingKnown); | |||
1805 | Known.One.clearAllBits(); | |||
1806 | } | |||
1807 | break; | |||
1808 | } | |||
1809 | case Intrinsic::umin: | |||
1810 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1811 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1812 | Known = KnownBits::umin(Known, Known2); | |||
1813 | break; | |||
1814 | case Intrinsic::umax: | |||
1815 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1816 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1817 | Known = KnownBits::umax(Known, Known2); | |||
1818 | break; | |||
1819 | case Intrinsic::smin: | |||
1820 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1821 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1822 | Known = KnownBits::smin(Known, Known2); | |||
1823 | break; | |||
1824 | case Intrinsic::smax: | |||
1825 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1826 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1827 | Known = KnownBits::smax(Known, Known2); | |||
1828 | break; | |||
1829 | case Intrinsic::x86_sse42_crc32_64_64: | |||
1830 | Known.Zero.setBitsFrom(32); | |||
1831 | break; | |||
1832 | case Intrinsic::riscv_vsetvli: | |||
1833 | case Intrinsic::riscv_vsetvlimax: | |||
1834 | // Assume that VL output is >= 65536. | |||
1835 | // TODO: Take SEW and LMUL into account. | |||
1836 | if (BitWidth > 17) | |||
1837 | Known.Zero.setBitsFrom(17); | |||
1838 | break; | |||
1839 | case Intrinsic::vscale: { | |||
1840 | if (!II->getParent() || !II->getFunction()) | |||
1841 | break; | |||
1842 | ||||
1843 | Known = getVScaleRange(II->getFunction(), BitWidth).toKnownBits(); | |||
1844 | break; | |||
1845 | } | |||
1846 | } | |||
1847 | } | |||
1848 | break; | |||
1849 | case Instruction::ShuffleVector: { | |||
1850 | auto *Shuf = dyn_cast<ShuffleVectorInst>(I); | |||
1851 | // FIXME: Do we need to handle ConstantExpr involving shufflevectors? | |||
1852 | if (!Shuf) { | |||
1853 | Known.resetAll(); | |||
1854 | return; | |||
1855 | } | |||
1856 | // For undef elements, we don't know anything about the common state of | |||
1857 | // the shuffle result. | |||
1858 | APInt DemandedLHS, DemandedRHS; | |||
1859 | if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) { | |||
1860 | Known.resetAll(); | |||
1861 | return; | |||
1862 | } | |||
1863 | Known.One.setAllBits(); | |||
1864 | Known.Zero.setAllBits(); | |||
1865 | if (!!DemandedLHS) { | |||
1866 | const Value *LHS = Shuf->getOperand(0); | |||
1867 | computeKnownBits(LHS, DemandedLHS, Known, Depth + 1, Q); | |||
1868 | // If we don't know any bits, early out. | |||
1869 | if (Known.isUnknown()) | |||
1870 | break; | |||
1871 | } | |||
1872 | if (!!DemandedRHS) { | |||
1873 | const Value *RHS = Shuf->getOperand(1); | |||
1874 | computeKnownBits(RHS, DemandedRHS, Known2, Depth + 1, Q); | |||
1875 | Known = KnownBits::commonBits(Known, Known2); | |||
1876 | } | |||
1877 | break; | |||
1878 | } | |||
1879 | case Instruction::InsertElement: { | |||
1880 | if (isa<ScalableVectorType>(I->getType())) { | |||
1881 | Known.resetAll(); | |||
1882 | return; | |||
1883 | } | |||
1884 | const Value *Vec = I->getOperand(0); | |||
1885 | const Value *Elt = I->getOperand(1); | |||
1886 | auto *CIdx = dyn_cast<ConstantInt>(I->getOperand(2)); | |||
1887 | // Early out if the index is non-constant or out-of-range. | |||
1888 | unsigned NumElts = DemandedElts.getBitWidth(); | |||
1889 | if (!CIdx || CIdx->getValue().uge(NumElts)) { | |||
1890 | Known.resetAll(); | |||
1891 | return; | |||
1892 | } | |||
1893 | Known.One.setAllBits(); | |||
1894 | Known.Zero.setAllBits(); | |||
1895 | unsigned EltIdx = CIdx->getZExtValue(); | |||
1896 | // Do we demand the inserted element? | |||
1897 | if (DemandedElts[EltIdx]) { | |||
1898 | computeKnownBits(Elt, Known, Depth + 1, Q); | |||
1899 | // If we don't know any bits, early out. | |||
1900 | if (Known.isUnknown()) | |||
1901 | break; | |||
1902 | } | |||
1903 | // We don't need the base vector element that has been inserted. | |||
1904 | APInt DemandedVecElts = DemandedElts; | |||
1905 | DemandedVecElts.clearBit(EltIdx); | |||
1906 | if (!!DemandedVecElts) { | |||
1907 | computeKnownBits(Vec, DemandedVecElts, Known2, Depth + 1, Q); | |||
1908 | Known = KnownBits::commonBits(Known, Known2); | |||
1909 | } | |||
1910 | break; | |||
1911 | } | |||
1912 | case Instruction::ExtractElement: { | |||
1913 | // Look through extract element. If the index is non-constant or | |||
1914 | // out-of-range demand all elements, otherwise just the extracted element. | |||
1915 | const Value *Vec = I->getOperand(0); | |||
1916 | const Value *Idx = I->getOperand(1); | |||
1917 | auto *CIdx = dyn_cast<ConstantInt>(Idx); | |||
1918 | if (isa<ScalableVectorType>(Vec->getType())) { | |||
1919 | // FIXME: there's probably *something* we can do with scalable vectors | |||
1920 | Known.resetAll(); | |||
1921 | break; | |||
1922 | } | |||
1923 | unsigned NumElts = cast<FixedVectorType>(Vec->getType())->getNumElements(); | |||
1924 | APInt DemandedVecElts = APInt::getAllOnes(NumElts); | |||
1925 | if (CIdx && CIdx->getValue().ult(NumElts)) | |||
1926 | DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue()); | |||
1927 | computeKnownBits(Vec, DemandedVecElts, Known, Depth + 1, Q); | |||
1928 | break; | |||
1929 | } | |||
1930 | case Instruction::ExtractValue: | |||
1931 | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I->getOperand(0))) { | |||
1932 | const ExtractValueInst *EVI = cast<ExtractValueInst>(I); | |||
1933 | if (EVI->getNumIndices() != 1) break; | |||
1934 | if (EVI->getIndices()[0] == 0) { | |||
1935 | switch (II->getIntrinsicID()) { | |||
1936 | default: break; | |||
1937 | case Intrinsic::uadd_with_overflow: | |||
1938 | case Intrinsic::sadd_with_overflow: | |||
1939 | computeKnownBitsAddSub(true, II->getArgOperand(0), | |||
1940 | II->getArgOperand(1), false, DemandedElts, | |||
1941 | Known, Known2, Depth, Q); | |||
1942 | break; | |||
1943 | case Intrinsic::usub_with_overflow: | |||
1944 | case Intrinsic::ssub_with_overflow: | |||
1945 | computeKnownBitsAddSub(false, II->getArgOperand(0), | |||
1946 | II->getArgOperand(1), false, DemandedElts, | |||
1947 | Known, Known2, Depth, Q); | |||
1948 | break; | |||
1949 | case Intrinsic::umul_with_overflow: | |||
1950 | case Intrinsic::smul_with_overflow: | |||
1951 | computeKnownBitsMul(II->getArgOperand(0), II->getArgOperand(1), false, | |||
1952 | DemandedElts, Known, Known2, Depth, Q); | |||
1953 | break; | |||
1954 | } | |||
1955 | } | |||
1956 | } | |||
1957 | break; | |||
1958 | case Instruction::Freeze: | |||
1959 | if (isGuaranteedNotToBePoison(I->getOperand(0), Q.AC, Q.CxtI, Q.DT, | |||
1960 | Depth + 1)) | |||
1961 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1962 | break; | |||
1963 | } | |||
1964 | } | |||
1965 | ||||
1966 | /// Determine which bits of V are known to be either zero or one and return | |||
1967 | /// them. | |||
1968 | KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
1969 | unsigned Depth, const Query &Q) { | |||
1970 | KnownBits Known(getBitWidth(V->getType(), Q.DL)); | |||
1971 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
1972 | return Known; | |||
1973 | } | |||
1974 | ||||
1975 | /// Determine which bits of V are known to be either zero or one and return | |||
1976 | /// them. | |||
1977 | KnownBits computeKnownBits(const Value *V, unsigned Depth, const Query &Q) { | |||
1978 | KnownBits Known(getBitWidth(V->getType(), Q.DL)); | |||
1979 | computeKnownBits(V, Known, Depth, Q); | |||
1980 | return Known; | |||
1981 | } | |||
1982 | ||||
1983 | /// Determine which bits of V are known to be either zero or one and return | |||
1984 | /// them in the Known bit set. | |||
1985 | /// | |||
1986 | /// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that | |||
1987 | /// we cannot optimize based on the assumption that it is zero without changing | |||
1988 | /// it to be an explicit zero. If we don't change it to zero, other code could | |||
1989 | /// optimized based on the contradictory assumption that it is non-zero. | |||
1990 | /// Because instcombine aggressively folds operations with undef args anyway, | |||
1991 | /// this won't lose us code quality. | |||
1992 | /// | |||
1993 | /// This function is defined on values with integer type, values with pointer | |||
1994 | /// type, and vectors of integers. In the case | |||
1995 | /// where V is a vector, known zero, and known one values are the | |||
1996 | /// same width as the vector element, and the bit is set only if it is true | |||
1997 | /// for all of the demanded elements in the vector specified by DemandedElts. | |||
1998 | void computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
1999 | KnownBits &Known, unsigned Depth, const Query &Q) { | |||
2000 | if (!DemandedElts) { | |||
2001 | // No demanded elts, better to assume we don't know anything. | |||
2002 | Known.resetAll(); | |||
2003 | return; | |||
2004 | } | |||
2005 | ||||
2006 | assert(V && "No Value?")(static_cast <bool> (V && "No Value?") ? void ( 0) : __assert_fail ("V && \"No Value?\"", "llvm/lib/Analysis/ValueTracking.cpp" , 2006, __extension__ __PRETTY_FUNCTION__)); | |||
2007 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2007, __extension__ __PRETTY_FUNCTION__ )); | |||
2008 | ||||
2009 | #ifndef NDEBUG | |||
2010 | Type *Ty = V->getType(); | |||
2011 | unsigned BitWidth = Known.getBitWidth(); | |||
2012 | ||||
2013 | assert((Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) &&(static_cast <bool> ((Ty->isIntOrIntVectorTy(BitWidth ) || Ty->isPtrOrPtrVectorTy()) && "Not integer or pointer type!" ) ? void (0) : __assert_fail ("(Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2014, __extension__ __PRETTY_FUNCTION__ )) | |||
2014 | "Not integer or pointer type!")(static_cast <bool> ((Ty->isIntOrIntVectorTy(BitWidth ) || Ty->isPtrOrPtrVectorTy()) && "Not integer or pointer type!" ) ? void (0) : __assert_fail ("(Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2014, __extension__ __PRETTY_FUNCTION__ )); | |||
2015 | ||||
2016 | if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) { | |||
2017 | assert((static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2019, __extension__ __PRETTY_FUNCTION__ )) | |||
2018 | FVTy->getNumElements() == DemandedElts.getBitWidth() &&(static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2019, __extension__ __PRETTY_FUNCTION__ )) | |||
2019 | "DemandedElt width should equal the fixed vector number of elements")(static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2019, __extension__ __PRETTY_FUNCTION__ )); | |||
2020 | } else { | |||
2021 | assert(DemandedElts == APInt(1, 1) &&(static_cast <bool> (DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars or scalable vectors" ) ? void (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars or scalable vectors\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2022, __extension__ __PRETTY_FUNCTION__ )) | |||
2022 | "DemandedElt width should be 1 for scalars or scalable vectors")(static_cast <bool> (DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars or scalable vectors" ) ? void (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars or scalable vectors\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2022, __extension__ __PRETTY_FUNCTION__ )); | |||
2023 | } | |||
2024 | ||||
2025 | Type *ScalarTy = Ty->getScalarType(); | |||
2026 | if (ScalarTy->isPointerTy()) { | |||
2027 | assert(BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) &&(static_cast <bool> (BitWidth == Q.DL.getPointerTypeSizeInBits (ScalarTy) && "V and Known should have same BitWidth" ) ? void (0) : __assert_fail ("BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2028, __extension__ __PRETTY_FUNCTION__ )) | |||
2028 | "V and Known should have same BitWidth")(static_cast <bool> (BitWidth == Q.DL.getPointerTypeSizeInBits (ScalarTy) && "V and Known should have same BitWidth" ) ? void (0) : __assert_fail ("BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2028, __extension__ __PRETTY_FUNCTION__ )); | |||
2029 | } else { | |||
2030 | assert(BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) &&(static_cast <bool> (BitWidth == Q.DL.getTypeSizeInBits (ScalarTy) && "V and Known should have same BitWidth" ) ? void (0) : __assert_fail ("BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2031, __extension__ __PRETTY_FUNCTION__ )) | |||
2031 | "V and Known should have same BitWidth")(static_cast <bool> (BitWidth == Q.DL.getTypeSizeInBits (ScalarTy) && "V and Known should have same BitWidth" ) ? void (0) : __assert_fail ("BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2031, __extension__ __PRETTY_FUNCTION__ )); | |||
2032 | } | |||
2033 | #endif | |||
2034 | ||||
2035 | const APInt *C; | |||
2036 | if (match(V, m_APInt(C))) { | |||
2037 | // We know all of the bits for a scalar constant or a splat vector constant! | |||
2038 | Known = KnownBits::makeConstant(*C); | |||
2039 | return; | |||
2040 | } | |||
2041 | // Null and aggregate-zero are all-zeros. | |||
2042 | if (isa<ConstantPointerNull>(V) || isa<ConstantAggregateZero>(V)) { | |||
2043 | Known.setAllZero(); | |||
2044 | return; | |||
2045 | } | |||
2046 | // Handle a constant vector by taking the intersection of the known bits of | |||
2047 | // each element. | |||
2048 | if (const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(V)) { | |||
2049 | assert(!isa<ScalableVectorType>(V->getType()))(static_cast <bool> (!isa<ScalableVectorType>(V-> getType())) ? void (0) : __assert_fail ("!isa<ScalableVectorType>(V->getType())" , "llvm/lib/Analysis/ValueTracking.cpp", 2049, __extension__ __PRETTY_FUNCTION__ )); | |||
2050 | // We know that CDV must be a vector of integers. Take the intersection of | |||
2051 | // each element. | |||
2052 | Known.Zero.setAllBits(); Known.One.setAllBits(); | |||
2053 | for (unsigned i = 0, e = CDV->getNumElements(); i != e; ++i) { | |||
2054 | if (!DemandedElts[i]) | |||
2055 | continue; | |||
2056 | APInt Elt = CDV->getElementAsAPInt(i); | |||
2057 | Known.Zero &= ~Elt; | |||
2058 | Known.One &= Elt; | |||
2059 | } | |||
2060 | return; | |||
2061 | } | |||
2062 | ||||
2063 | if (const auto *CV = dyn_cast<ConstantVector>(V)) { | |||
2064 | assert(!isa<ScalableVectorType>(V->getType()))(static_cast <bool> (!isa<ScalableVectorType>(V-> getType())) ? void (0) : __assert_fail ("!isa<ScalableVectorType>(V->getType())" , "llvm/lib/Analysis/ValueTracking.cpp", 2064, __extension__ __PRETTY_FUNCTION__ )); | |||
2065 | // We know that CV must be a vector of integers. Take the intersection of | |||
2066 | // each element. | |||
2067 | Known.Zero.setAllBits(); Known.One.setAllBits(); | |||
2068 | for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) { | |||
2069 | if (!DemandedElts[i]) | |||
2070 | continue; | |||
2071 | Constant *Element = CV->getAggregateElement(i); | |||
2072 | auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element); | |||
2073 | if (!ElementCI) { | |||
2074 | Known.resetAll(); | |||
2075 | return; | |||
2076 | } | |||
2077 | const APInt &Elt = ElementCI->getValue(); | |||
2078 | Known.Zero &= ~Elt; | |||
2079 | Known.One &= Elt; | |||
2080 | } | |||
2081 | return; | |||
2082 | } | |||
2083 | ||||
2084 | // Start out not knowing anything. | |||
2085 | Known.resetAll(); | |||
2086 | ||||
2087 | // We can't imply anything about undefs. | |||
2088 | if (isa<UndefValue>(V)) | |||
2089 | return; | |||
2090 | ||||
2091 | // There's no point in looking through other users of ConstantData for | |||
2092 | // assumptions. Confirm that we've handled them all. | |||
2093 | assert(!isa<ConstantData>(V) && "Unhandled constant data!")(static_cast <bool> (!isa<ConstantData>(V) && "Unhandled constant data!") ? void (0) : __assert_fail ("!isa<ConstantData>(V) && \"Unhandled constant data!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2093, __extension__ __PRETTY_FUNCTION__ )); | |||
2094 | ||||
2095 | // All recursive calls that increase depth must come after this. | |||
2096 | if (Depth == MaxAnalysisRecursionDepth) | |||
2097 | return; | |||
2098 | ||||
2099 | // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has | |||
2100 | // the bits of its aliasee. | |||
2101 | if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { | |||
2102 | if (!GA->isInterposable()) | |||
2103 | computeKnownBits(GA->getAliasee(), Known, Depth + 1, Q); | |||
2104 | return; | |||
2105 | } | |||
2106 | ||||
2107 | if (const Operator *I = dyn_cast<Operator>(V)) | |||
2108 | computeKnownBitsFromOperator(I, DemandedElts, Known, Depth, Q); | |||
2109 | ||||
2110 | // Aligned pointers have trailing zeros - refine Known.Zero set | |||
2111 | if (isa<PointerType>(V->getType())) { | |||
2112 | Align Alignment = V->getPointerAlignment(Q.DL); | |||
2113 | Known.Zero.setLowBits(Log2(Alignment)); | |||
2114 | } | |||
2115 | ||||
2116 | // computeKnownBitsFromAssume strictly refines Known. | |||
2117 | // Therefore, we run them after computeKnownBitsFromOperator. | |||
2118 | ||||
2119 | // Check whether a nearby assume intrinsic can determine some known bits. | |||
2120 | computeKnownBitsFromAssume(V, Known, Depth, Q); | |||
2121 | ||||
2122 | assert((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?")(static_cast <bool> ((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?") ? void (0) : __assert_fail ("(Known.Zero & Known.One) == 0 && \"Bits known to be one AND zero?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2122, __extension__ __PRETTY_FUNCTION__ )); | |||
2123 | } | |||
2124 | ||||
2125 | /// Try to detect a recurrence that the value of the induction variable is | |||
2126 | /// always a power of two (or zero). | |||
2127 | static bool isPowerOfTwoRecurrence(const PHINode *PN, bool OrZero, | |||
2128 | unsigned Depth, Query &Q) { | |||
2129 | BinaryOperator *BO = nullptr; | |||
2130 | Value *Start = nullptr, *Step = nullptr; | |||
2131 | if (!matchSimpleRecurrence(PN, BO, Start, Step)) | |||
2132 | return false; | |||
2133 | ||||
2134 | // Initial value must be a power of two. | |||
2135 | for (const Use &U : PN->operands()) { | |||
2136 | if (U.get() == Start) { | |||
2137 | // Initial value comes from a different BB, need to adjust context | |||
2138 | // instruction for analysis. | |||
2139 | Q.CxtI = PN->getIncomingBlock(U)->getTerminator(); | |||
2140 | if (!isKnownToBeAPowerOfTwo(Start, OrZero, Depth, Q)) | |||
2141 | return false; | |||
2142 | } | |||
2143 | } | |||
2144 | ||||
2145 | // Except for Mul, the induction variable must be on the left side of the | |||
2146 | // increment expression, otherwise its value can be arbitrary. | |||
2147 | if (BO->getOpcode() != Instruction::Mul && BO->getOperand(1) != Step) | |||
2148 | return false; | |||
2149 | ||||
2150 | Q.CxtI = BO->getParent()->getTerminator(); | |||
2151 | switch (BO->getOpcode()) { | |||
2152 | case Instruction::Mul: | |||
2153 | // Power of two is closed under multiplication. | |||
2154 | return (OrZero || Q.IIQ.hasNoUnsignedWrap(BO) || | |||
2155 | Q.IIQ.hasNoSignedWrap(BO)) && | |||
2156 | isKnownToBeAPowerOfTwo(Step, OrZero, Depth, Q); | |||
2157 | case Instruction::SDiv: | |||
2158 | // Start value must not be signmask for signed division, so simply being a | |||
2159 | // power of two is not sufficient, and it has to be a constant. | |||
2160 | if (!match(Start, m_Power2()) || match(Start, m_SignMask())) | |||
2161 | return false; | |||
2162 | [[fallthrough]]; | |||
2163 | case Instruction::UDiv: | |||
2164 | // Divisor must be a power of two. | |||
2165 | // If OrZero is false, cannot guarantee induction variable is non-zero after | |||
2166 | // division, same for Shr, unless it is exact division. | |||
2167 | return (OrZero || Q.IIQ.isExact(BO)) && | |||
2168 | isKnownToBeAPowerOfTwo(Step, false, Depth, Q); | |||
2169 | case Instruction::Shl: | |||
2170 | return OrZero || Q.IIQ.hasNoUnsignedWrap(BO) || Q.IIQ.hasNoSignedWrap(BO); | |||
2171 | case Instruction::AShr: | |||
2172 | if (!match(Start, m_Power2()) || match(Start, m_SignMask())) | |||
2173 | return false; | |||
2174 | [[fallthrough]]; | |||
2175 | case Instruction::LShr: | |||
2176 | return OrZero || Q.IIQ.isExact(BO); | |||
2177 | default: | |||
2178 | return false; | |||
2179 | } | |||
2180 | } | |||
2181 | ||||
2182 | /// Return true if the given value is known to have exactly one | |||
2183 | /// bit set when defined. For vectors return true if every element is known to | |||
2184 | /// be a power of two when defined. Supports values with integer or pointer | |||
2185 | /// types and vectors of integers. | |||
2186 | bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, | |||
2187 | const Query &Q) { | |||
2188 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2188, __extension__ __PRETTY_FUNCTION__ )); | |||
2189 | ||||
2190 | // Attempt to match against constants. | |||
2191 | if (OrZero && match(V, m_Power2OrZero())) | |||
2192 | return true; | |||
2193 | if (match(V, m_Power2())) | |||
2194 | return true; | |||
2195 | ||||
2196 | // 1 << X is clearly a power of two if the one is not shifted off the end. If | |||
2197 | // it is shifted off the end then the result is undefined. | |||
2198 | if (match(V, m_Shl(m_One(), m_Value()))) | |||
2199 | return true; | |||
2200 | ||||
2201 | // (signmask) >>l X is clearly a power of two if the one is not shifted off | |||
2202 | // the bottom. If it is shifted off the bottom then the result is undefined. | |||
2203 | if (match(V, m_LShr(m_SignMask(), m_Value()))) | |||
2204 | return true; | |||
2205 | ||||
2206 | // The remaining tests are all recursive, so bail out if we hit the limit. | |||
2207 | if (Depth++ == MaxAnalysisRecursionDepth) | |||
2208 | return false; | |||
2209 | ||||
2210 | Value *X = nullptr, *Y = nullptr; | |||
2211 | // A shift left or a logical shift right of a power of two is a power of two | |||
2212 | // or zero. | |||
2213 | if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) || | |||
2214 | match(V, m_LShr(m_Value(X), m_Value())))) | |||
2215 | return isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q); | |||
2216 | ||||
2217 | if (const ZExtInst *ZI = dyn_cast<ZExtInst>(V)) | |||
2218 | return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth, Q); | |||
2219 | ||||
2220 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) | |||
2221 | return isKnownToBeAPowerOfTwo(SI->getTrueValue(), OrZero, Depth, Q) && | |||
2222 | isKnownToBeAPowerOfTwo(SI->getFalseValue(), OrZero, Depth, Q); | |||
2223 | ||||
2224 | // Peek through min/max. | |||
2225 | if (match(V, m_MaxOrMin(m_Value(X), m_Value(Y)))) { | |||
2226 | return isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q) && | |||
2227 | isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q); | |||
2228 | } | |||
2229 | ||||
2230 | if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) { | |||
2231 | // A power of two and'd with anything is a power of two or zero. | |||
2232 | if (isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q) || | |||
2233 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, Depth, Q)) | |||
2234 | return true; | |||
2235 | // X & (-X) is always a power of two or zero. | |||
2236 | if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X)))) | |||
2237 | return true; | |||
2238 | return false; | |||
2239 | } | |||
2240 | ||||
2241 | // Adding a power-of-two or zero to the same power-of-two or zero yields | |||
2242 | // either the original power-of-two, a larger power-of-two or zero. | |||
2243 | if (match(V, m_Add(m_Value(X), m_Value(Y)))) { | |||
2244 | const OverflowingBinaryOperator *VOBO = cast<OverflowingBinaryOperator>(V); | |||
2245 | if (OrZero || Q.IIQ.hasNoUnsignedWrap(VOBO) || | |||
2246 | Q.IIQ.hasNoSignedWrap(VOBO)) { | |||
2247 | if (match(X, m_And(m_Specific(Y), m_Value())) || | |||
2248 | match(X, m_And(m_Value(), m_Specific(Y)))) | |||
2249 | if (isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q)) | |||
2250 | return true; | |||
2251 | if (match(Y, m_And(m_Specific(X), m_Value())) || | |||
2252 | match(Y, m_And(m_Value(), m_Specific(X)))) | |||
2253 | if (isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q)) | |||
2254 | return true; | |||
2255 | ||||
2256 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); | |||
2257 | KnownBits LHSBits(BitWidth); | |||
2258 | computeKnownBits(X, LHSBits, Depth, Q); | |||
2259 | ||||
2260 | KnownBits RHSBits(BitWidth); | |||
2261 | computeKnownBits(Y, RHSBits, Depth, Q); | |||
2262 | // If i8 V is a power of two or zero: | |||
2263 | // ZeroBits: 1 1 1 0 1 1 1 1 | |||
2264 | // ~ZeroBits: 0 0 0 1 0 0 0 0 | |||
2265 | if ((~(LHSBits.Zero & RHSBits.Zero)).isPowerOf2()) | |||
2266 | // If OrZero isn't set, we cannot give back a zero result. | |||
2267 | // Make sure either the LHS or RHS has a bit set. | |||
2268 | if (OrZero || RHSBits.One.getBoolValue() || LHSBits.One.getBoolValue()) | |||
2269 | return true; | |||
2270 | } | |||
2271 | } | |||
2272 | ||||
2273 | // A PHI node is power of two if all incoming values are power of two, or if | |||
2274 | // it is an induction variable where in each step its value is a power of two. | |||
2275 | if (const PHINode *PN = dyn_cast<PHINode>(V)) { | |||
2276 | Query RecQ = Q; | |||
2277 | ||||
2278 | // Check if it is an induction variable and always power of two. | |||
2279 | if (isPowerOfTwoRecurrence(PN, OrZero, Depth, RecQ)) | |||
2280 | return true; | |||
2281 | ||||
2282 | // Recursively check all incoming values. Limit recursion to 2 levels, so | |||
2283 | // that search complexity is limited to number of operands^2. | |||
2284 | unsigned NewDepth = std::max(Depth, MaxAnalysisRecursionDepth - 1); | |||
2285 | return llvm::all_of(PN->operands(), [&](const Use &U) { | |||
2286 | // Value is power of 2 if it is coming from PHI node itself by induction. | |||
2287 | if (U.get() == PN) | |||
2288 | return true; | |||
2289 | ||||
2290 | // Change the context instruction to the incoming block where it is | |||
2291 | // evaluated. | |||
2292 | RecQ.CxtI = PN->getIncomingBlock(U)->getTerminator(); | |||
2293 | return isKnownToBeAPowerOfTwo(U.get(), OrZero, NewDepth, RecQ); | |||
2294 | }); | |||
2295 | } | |||
2296 | ||||
2297 | // An exact divide or right shift can only shift off zero bits, so the result | |||
2298 | // is a power of two only if the first operand is a power of two and not | |||
2299 | // copying a sign bit (sdiv int_min, 2). | |||
2300 | if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) || | |||
2301 | match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) { | |||
2302 | return isKnownToBeAPowerOfTwo(cast<Operator>(V)->getOperand(0), OrZero, | |||
2303 | Depth, Q); | |||
2304 | } | |||
2305 | ||||
2306 | return false; | |||
2307 | } | |||
2308 | ||||
2309 | /// Test whether a GEP's result is known to be non-null. | |||
2310 | /// | |||
2311 | /// Uses properties inherent in a GEP to try to determine whether it is known | |||
2312 | /// to be non-null. | |||
2313 | /// | |||
2314 | /// Currently this routine does not support vector GEPs. | |||
2315 | static bool isGEPKnownNonNull(const GEPOperator *GEP, unsigned Depth, | |||
2316 | const Query &Q) { | |||
2317 | const Function *F = nullptr; | |||
2318 | if (const Instruction *I = dyn_cast<Instruction>(GEP)) | |||
2319 | F = I->getFunction(); | |||
2320 | ||||
2321 | if (!GEP->isInBounds() || | |||
2322 | NullPointerIsDefined(F, GEP->getPointerAddressSpace())) | |||
2323 | return false; | |||
2324 | ||||
2325 | // FIXME: Support vector-GEPs. | |||
2326 | assert(GEP->getType()->isPointerTy() && "We only support plain pointer GEP")(static_cast <bool> (GEP->getType()->isPointerTy( ) && "We only support plain pointer GEP") ? void (0) : __assert_fail ("GEP->getType()->isPointerTy() && \"We only support plain pointer GEP\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2326, __extension__ __PRETTY_FUNCTION__ )); | |||
2327 | ||||
2328 | // If the base pointer is non-null, we cannot walk to a null address with an | |||
2329 | // inbounds GEP in address space zero. | |||
2330 | if (isKnownNonZero(GEP->getPointerOperand(), Depth, Q)) | |||
2331 | return true; | |||
2332 | ||||
2333 | // Walk the GEP operands and see if any operand introduces a non-zero offset. | |||
2334 | // If so, then the GEP cannot produce a null pointer, as doing so would | |||
2335 | // inherently violate the inbounds contract within address space zero. | |||
2336 | for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP); | |||
2337 | GTI != GTE; ++GTI) { | |||
2338 | // Struct types are easy -- they must always be indexed by a constant. | |||
2339 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
2340 | ConstantInt *OpC = cast<ConstantInt>(GTI.getOperand()); | |||
2341 | unsigned ElementIdx = OpC->getZExtValue(); | |||
2342 | const StructLayout *SL = Q.DL.getStructLayout(STy); | |||
2343 | uint64_t ElementOffset = SL->getElementOffset(ElementIdx); | |||
2344 | if (ElementOffset > 0) | |||
2345 | return true; | |||
2346 | continue; | |||
2347 | } | |||
2348 | ||||
2349 | // If we have a zero-sized type, the index doesn't matter. Keep looping. | |||
2350 | if (Q.DL.getTypeAllocSize(GTI.getIndexedType()).isZero()) | |||
2351 | continue; | |||
2352 | ||||
2353 | // Fast path the constant operand case both for efficiency and so we don't | |||
2354 | // increment Depth when just zipping down an all-constant GEP. | |||
2355 | if (ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand())) { | |||
2356 | if (!OpC->isZero()) | |||
2357 | return true; | |||
2358 | continue; | |||
2359 | } | |||
2360 | ||||
2361 | // We post-increment Depth here because while isKnownNonZero increments it | |||
2362 | // as well, when we pop back up that increment won't persist. We don't want | |||
2363 | // to recurse 10k times just because we have 10k GEP operands. We don't | |||
2364 | // bail completely out because we want to handle constant GEPs regardless | |||
2365 | // of depth. | |||
2366 | if (Depth++ >= MaxAnalysisRecursionDepth) | |||
2367 | continue; | |||
2368 | ||||
2369 | if (isKnownNonZero(GTI.getOperand(), Depth, Q)) | |||
2370 | return true; | |||
2371 | } | |||
2372 | ||||
2373 | return false; | |||
2374 | } | |||
2375 | ||||
2376 | static bool isKnownNonNullFromDominatingCondition(const Value *V, | |||
2377 | const Instruction *CtxI, | |||
2378 | const DominatorTree *DT) { | |||
2379 | assert(!isa<Constant>(V) && "Called for constant?")(static_cast <bool> (!isa<Constant>(V) && "Called for constant?") ? void (0) : __assert_fail ("!isa<Constant>(V) && \"Called for constant?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2379, __extension__ __PRETTY_FUNCTION__ )); | |||
2380 | ||||
2381 | if (!CtxI || !DT) | |||
2382 | return false; | |||
2383 | ||||
2384 | unsigned NumUsesExplored = 0; | |||
2385 | for (const auto *U : V->users()) { | |||
2386 | // Avoid massive lists | |||
2387 | if (NumUsesExplored >= DomConditionsMaxUses) | |||
2388 | break; | |||
2389 | NumUsesExplored++; | |||
2390 | ||||
2391 | // If the value is used as an argument to a call or invoke, then argument | |||
2392 | // attributes may provide an answer about null-ness. | |||
2393 | if (const auto *CB = dyn_cast<CallBase>(U)) | |||
2394 | if (auto *CalledFunc = CB->getCalledFunction()) | |||
2395 | for (const Argument &Arg : CalledFunc->args()) | |||
2396 | if (CB->getArgOperand(Arg.getArgNo()) == V && | |||
2397 | Arg.hasNonNullAttr(/* AllowUndefOrPoison */ false) && | |||
2398 | DT->dominates(CB, CtxI)) | |||
2399 | return true; | |||
2400 | ||||
2401 | // If the value is used as a load/store, then the pointer must be non null. | |||
2402 | if (V == getLoadStorePointerOperand(U)) { | |||
2403 | const Instruction *I = cast<Instruction>(U); | |||
2404 | if (!NullPointerIsDefined(I->getFunction(), | |||
2405 | V->getType()->getPointerAddressSpace()) && | |||
2406 | DT->dominates(I, CtxI)) | |||
2407 | return true; | |||
2408 | } | |||
2409 | ||||
2410 | // Consider only compare instructions uniquely controlling a branch | |||
2411 | Value *RHS; | |||
2412 | CmpInst::Predicate Pred; | |||
2413 | if (!match(U, m_c_ICmp(Pred, m_Specific(V), m_Value(RHS)))) | |||
2414 | continue; | |||
2415 | ||||
2416 | bool NonNullIfTrue; | |||
2417 | if (cmpExcludesZero(Pred, RHS)) | |||
2418 | NonNullIfTrue = true; | |||
2419 | else if (cmpExcludesZero(CmpInst::getInversePredicate(Pred), RHS)) | |||
2420 | NonNullIfTrue = false; | |||
2421 | else | |||
2422 | continue; | |||
2423 | ||||
2424 | SmallVector<const User *, 4> WorkList; | |||
2425 | SmallPtrSet<const User *, 4> Visited; | |||
2426 | for (const auto *CmpU : U->users()) { | |||
2427 | assert(WorkList.empty() && "Should be!")(static_cast <bool> (WorkList.empty() && "Should be!" ) ? void (0) : __assert_fail ("WorkList.empty() && \"Should be!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2427, __extension__ __PRETTY_FUNCTION__ )); | |||
2428 | if (Visited.insert(CmpU).second) | |||
2429 | WorkList.push_back(CmpU); | |||
2430 | ||||
2431 | while (!WorkList.empty()) { | |||
2432 | auto *Curr = WorkList.pop_back_val(); | |||
2433 | ||||
2434 | // If a user is an AND, add all its users to the work list. We only | |||
2435 | // propagate "pred != null" condition through AND because it is only | |||
2436 | // correct to assume that all conditions of AND are met in true branch. | |||
2437 | // TODO: Support similar logic of OR and EQ predicate? | |||
2438 | if (NonNullIfTrue) | |||
2439 | if (match(Curr, m_LogicalAnd(m_Value(), m_Value()))) { | |||
2440 | for (const auto *CurrU : Curr->users()) | |||
2441 | if (Visited.insert(CurrU).second) | |||
2442 | WorkList.push_back(CurrU); | |||
2443 | continue; | |||
2444 | } | |||
2445 | ||||
2446 | if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) { | |||
2447 | assert(BI->isConditional() && "uses a comparison!")(static_cast <bool> (BI->isConditional() && "uses a comparison!" ) ? void (0) : __assert_fail ("BI->isConditional() && \"uses a comparison!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2447, __extension__ __PRETTY_FUNCTION__ )); | |||
2448 | ||||
2449 | BasicBlock *NonNullSuccessor = | |||
2450 | BI->getSuccessor(NonNullIfTrue ? 0 : 1); | |||
2451 | BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor); | |||
2452 | if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent())) | |||
2453 | return true; | |||
2454 | } else if (NonNullIfTrue && isGuard(Curr) && | |||
2455 | DT->dominates(cast<Instruction>(Curr), CtxI)) { | |||
2456 | return true; | |||
2457 | } | |||
2458 | } | |||
2459 | } | |||
2460 | } | |||
2461 | ||||
2462 | return false; | |||
2463 | } | |||
2464 | ||||
2465 | /// Does the 'Range' metadata (which must be a valid MD_range operand list) | |||
2466 | /// ensure that the value it's attached to is never Value? 'RangeType' is | |||
2467 | /// is the type of the value described by the range. | |||
2468 | static bool rangeMetadataExcludesValue(const MDNode* Ranges, const APInt& Value) { | |||
2469 | const unsigned NumRanges = Ranges->getNumOperands() / 2; | |||
2470 | assert(NumRanges >= 1)(static_cast <bool> (NumRanges >= 1) ? void (0) : __assert_fail ("NumRanges >= 1", "llvm/lib/Analysis/ValueTracking.cpp", 2470, __extension__ __PRETTY_FUNCTION__)); | |||
2471 | for (unsigned i = 0; i < NumRanges; ++i) { | |||
2472 | ConstantInt *Lower = | |||
2473 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 0)); | |||
2474 | ConstantInt *Upper = | |||
2475 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 1)); | |||
2476 | ConstantRange Range(Lower->getValue(), Upper->getValue()); | |||
2477 | if (Range.contains(Value)) | |||
2478 | return false; | |||
2479 | } | |||
2480 | return true; | |||
2481 | } | |||
2482 | ||||
2483 | /// Try to detect a recurrence that monotonically increases/decreases from a | |||
2484 | /// non-zero starting value. These are common as induction variables. | |||
2485 | static bool isNonZeroRecurrence(const PHINode *PN) { | |||
2486 | BinaryOperator *BO = nullptr; | |||
2487 | Value *Start = nullptr, *Step = nullptr; | |||
2488 | const APInt *StartC, *StepC; | |||
2489 | if (!matchSimpleRecurrence(PN, BO, Start, Step) || | |||
2490 | !match(Start, m_APInt(StartC)) || StartC->isZero()) | |||
2491 | return false; | |||
2492 | ||||
2493 | switch (BO->getOpcode()) { | |||
2494 | case Instruction::Add: | |||
2495 | // Starting from non-zero and stepping away from zero can never wrap back | |||
2496 | // to zero. | |||
2497 | return BO->hasNoUnsignedWrap() || | |||
2498 | (BO->hasNoSignedWrap() && match(Step, m_APInt(StepC)) && | |||
2499 | StartC->isNegative() == StepC->isNegative()); | |||
2500 | case Instruction::Mul: | |||
2501 | return (BO->hasNoUnsignedWrap() || BO->hasNoSignedWrap()) && | |||
2502 | match(Step, m_APInt(StepC)) && !StepC->isZero(); | |||
2503 | case Instruction::Shl: | |||
2504 | return BO->hasNoUnsignedWrap() || BO->hasNoSignedWrap(); | |||
2505 | case Instruction::AShr: | |||
2506 | case Instruction::LShr: | |||
2507 | return BO->isExact(); | |||
2508 | default: | |||
2509 | return false; | |||
2510 | } | |||
2511 | } | |||
2512 | ||||
2513 | static bool isNonZeroAdd(const APInt &DemandedElts, unsigned Depth, | |||
2514 | const Query &Q, unsigned BitWidth, Value *X, Value *Y, | |||
2515 | bool NSW) { | |||
2516 | KnownBits XKnown = computeKnownBits(X, DemandedElts, Depth, Q); | |||
2517 | KnownBits YKnown = computeKnownBits(Y, DemandedElts, Depth, Q); | |||
2518 | ||||
2519 | // If X and Y are both non-negative (as signed values) then their sum is not | |||
2520 | // zero unless both X and Y are zero. | |||
2521 | if (XKnown.isNonNegative() && YKnown.isNonNegative()) | |||
2522 | if (isKnownNonZero(Y, DemandedElts, Depth, Q) || | |||
2523 | isKnownNonZero(X, DemandedElts, Depth, Q)) | |||
2524 | return true; | |||
2525 | ||||
2526 | // If X and Y are both negative (as signed values) then their sum is not | |||
2527 | // zero unless both X and Y equal INT_MIN. | |||
2528 | if (XKnown.isNegative() && YKnown.isNegative()) { | |||
2529 | APInt Mask = APInt::getSignedMaxValue(BitWidth); | |||
2530 | // The sign bit of X is set. If some other bit is set then X is not equal | |||
2531 | // to INT_MIN. | |||
2532 | if (XKnown.One.intersects(Mask)) | |||
2533 | return true; | |||
2534 | // The sign bit of Y is set. If some other bit is set then Y is not equal | |||
2535 | // to INT_MIN. | |||
2536 | if (YKnown.One.intersects(Mask)) | |||
2537 | return true; | |||
2538 | } | |||
2539 | ||||
2540 | // The sum of a non-negative number and a power of two is not zero. | |||
2541 | if (XKnown.isNonNegative() && | |||
2542 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ false, Depth, Q)) | |||
2543 | return true; | |||
2544 | if (YKnown.isNonNegative() && | |||
2545 | isKnownToBeAPowerOfTwo(X, /*OrZero*/ false, Depth, Q)) | |||
2546 | return true; | |||
2547 | ||||
2548 | return KnownBits::computeForAddSub(/*Add*/ true, NSW, XKnown, YKnown) | |||
2549 | .isNonZero(); | |||
2550 | } | |||
2551 | ||||
2552 | static bool isNonZeroSub(const APInt &DemandedElts, unsigned Depth, | |||
2553 | const Query &Q, unsigned BitWidth, Value *X, | |||
2554 | Value *Y) { | |||
2555 | if (auto *C = dyn_cast<Constant>(X)) | |||
2556 | if (C->isNullValue() && isKnownNonZero(Y, DemandedElts, Depth, Q)) | |||
2557 | return true; | |||
2558 | ||||
2559 | KnownBits XKnown = computeKnownBits(X, DemandedElts, Depth, Q); | |||
2560 | if (XKnown.isUnknown()) | |||
2561 | return false; | |||
2562 | KnownBits YKnown = computeKnownBits(Y, DemandedElts, Depth, Q); | |||
2563 | // If X != Y then X - Y is non zero. | |||
2564 | std::optional<bool> ne = KnownBits::ne(XKnown, YKnown); | |||
2565 | // If we are unable to compute if X != Y, we won't be able to do anything | |||
2566 | // computing the knownbits of the sub expression so just return here. | |||
2567 | return ne && *ne; | |||
2568 | } | |||
2569 | ||||
2570 | static bool isNonZeroShift(const Operator *I, const APInt &DemandedElts, | |||
2571 | unsigned Depth, const Query &Q, | |||
2572 | const KnownBits &KnownVal) { | |||
2573 | auto ShiftOp = [&](const APInt &Lhs, const APInt &Rhs) { | |||
2574 | switch (I->getOpcode()) { | |||
2575 | case Instruction::Shl: | |||
2576 | return Lhs.shl(Rhs); | |||
2577 | case Instruction::LShr: | |||
2578 | return Lhs.lshr(Rhs); | |||
2579 | case Instruction::AShr: | |||
2580 | return Lhs.ashr(Rhs); | |||
2581 | default: | |||
2582 | llvm_unreachable("Unknown Shift Opcode")::llvm::llvm_unreachable_internal("Unknown Shift Opcode", "llvm/lib/Analysis/ValueTracking.cpp" , 2582); | |||
2583 | } | |||
2584 | }; | |||
2585 | ||||
2586 | auto InvShiftOp = [&](const APInt &Lhs, const APInt &Rhs) { | |||
2587 | switch (I->getOpcode()) { | |||
2588 | case Instruction::Shl: | |||
2589 | return Lhs.lshr(Rhs); | |||
2590 | case Instruction::LShr: | |||
2591 | case Instruction::AShr: | |||
2592 | return Lhs.shl(Rhs); | |||
2593 | default: | |||
2594 | llvm_unreachable("Unknown Shift Opcode")::llvm::llvm_unreachable_internal("Unknown Shift Opcode", "llvm/lib/Analysis/ValueTracking.cpp" , 2594); | |||
2595 | } | |||
2596 | }; | |||
2597 | ||||
2598 | if (KnownVal.isUnknown()) | |||
2599 | return false; | |||
2600 | ||||
2601 | KnownBits KnownCnt = | |||
2602 | computeKnownBits(I->getOperand(1), DemandedElts, Depth, Q); | |||
2603 | APInt MaxShift = KnownCnt.getMaxValue(); | |||
2604 | unsigned NumBits = KnownVal.getBitWidth(); | |||
2605 | if (MaxShift.uge(NumBits)) | |||
2606 | return false; | |||
2607 | ||||
2608 | if (!ShiftOp(KnownVal.One, MaxShift).isZero()) | |||
2609 | return true; | |||
2610 | ||||
2611 | // If all of the bits shifted out are known to be zero, and Val is known | |||
2612 | // non-zero then at least one non-zero bit must remain. | |||
2613 | if (InvShiftOp(KnownVal.Zero, NumBits - MaxShift) | |||
2614 | .eq(InvShiftOp(APInt::getAllOnes(NumBits), NumBits - MaxShift)) && | |||
2615 | isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q)) | |||
2616 | return true; | |||
2617 | ||||
2618 | return false; | |||
2619 | } | |||
2620 | ||||
2621 | /// Return true if the given value is known to be non-zero when defined. For | |||
2622 | /// vectors, return true if every demanded element is known to be non-zero when | |||
2623 | /// defined. For pointers, if the context instruction and dominator tree are | |||
2624 | /// specified, perform context-sensitive analysis and return true if the | |||
2625 | /// pointer couldn't possibly be null at the specified instruction. | |||
2626 | /// Supports values with integer or pointer type and vectors of integers. | |||
2627 | bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth, | |||
2628 | const Query &Q) { | |||
2629 | ||||
2630 | #ifndef NDEBUG | |||
2631 | Type *Ty = V->getType(); | |||
2632 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2632, __extension__ __PRETTY_FUNCTION__ )); | |||
2633 | ||||
2634 | if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) { | |||
2635 | assert((static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2637, __extension__ __PRETTY_FUNCTION__ )) | |||
2636 | FVTy->getNumElements() == DemandedElts.getBitWidth() &&(static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2637, __extension__ __PRETTY_FUNCTION__ )) | |||
2637 | "DemandedElt width should equal the fixed vector number of elements")(static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2637, __extension__ __PRETTY_FUNCTION__ )); | |||
2638 | } else { | |||
2639 | assert(DemandedElts == APInt(1, 1) &&(static_cast <bool> (DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2640, __extension__ __PRETTY_FUNCTION__ )) | |||
2640 | "DemandedElt width should be 1 for scalars")(static_cast <bool> (DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "llvm/lib/Analysis/ValueTracking.cpp", 2640, __extension__ __PRETTY_FUNCTION__ )); | |||
2641 | } | |||
2642 | #endif | |||
2643 | ||||
2644 | if (auto *C = dyn_cast<Constant>(V)) { | |||
2645 | if (C->isNullValue()) | |||
2646 | return false; | |||
2647 | if (isa<ConstantInt>(C)) | |||
2648 | // Must be non-zero due to null test above. | |||
2649 | return true; | |||
2650 | ||||
2651 | // For constant vectors, check that all elements are undefined or known | |||
2652 | // non-zero to determine that the whole vector is known non-zero. | |||
2653 | if (auto *VecTy = dyn_cast<FixedVectorType>(C->getType())) { | |||
2654 | for (unsigned i = 0, e = VecTy->getNumElements(); i != e; ++i) { | |||
2655 | if (!DemandedElts[i]) | |||
2656 | continue; | |||
2657 | Constant *Elt = C->getAggregateElement(i); | |||
2658 | if (!Elt || Elt->isNullValue()) | |||
2659 | return false; | |||
2660 | if (!isa<UndefValue>(Elt) && !isa<ConstantInt>(Elt)) | |||
2661 | return false; | |||
2662 | } | |||
2663 | return true; | |||
2664 | } | |||
2665 | ||||
2666 | // A global variable in address space 0 is non null unless extern weak | |||
2667 | // or an absolute symbol reference. Other address spaces may have null as a | |||
2668 | // valid address for a global, so we can't assume anything. | |||
2669 | if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) { | |||
2670 | if (!GV->isAbsoluteSymbolRef() && !GV->hasExternalWeakLinkage() && | |||
2671 | GV->getType()->getAddressSpace() == 0) | |||
2672 | return true; | |||
2673 | } | |||
2674 | ||||
2675 | // For constant expressions, fall through to the Operator code below. | |||
2676 | if (!isa<ConstantExpr>(V)) | |||
2677 | return false; | |||
2678 | } | |||
2679 | ||||
2680 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
2681 | if (MDNode *Ranges = Q.IIQ.getMetadata(I, LLVMContext::MD_range)) { | |||
2682 | // If the possible ranges don't contain zero, then the value is | |||
2683 | // definitely non-zero. | |||
2684 | if (auto *Ty = dyn_cast<IntegerType>(V->getType())) { | |||
2685 | const APInt ZeroValue(Ty->getBitWidth(), 0); | |||
2686 | if (rangeMetadataExcludesValue(Ranges, ZeroValue)) | |||
2687 | return true; | |||
2688 | } | |||
2689 | } | |||
2690 | } | |||
2691 | ||||
2692 | if (!isa<Constant>(V) && isKnownNonZeroFromAssume(V, Q)) | |||
2693 | return true; | |||
2694 | ||||
2695 | // Some of the tests below are recursive, so bail out if we hit the limit. | |||
2696 | if (Depth++ >= MaxAnalysisRecursionDepth) | |||
2697 | return false; | |||
2698 | ||||
2699 | // Check for pointer simplifications. | |||
2700 | ||||
2701 | if (PointerType *PtrTy = dyn_cast<PointerType>(V->getType())) { | |||
2702 | // Alloca never returns null, malloc might. | |||
2703 | if (isa<AllocaInst>(V) && Q.DL.getAllocaAddrSpace() == 0) | |||
2704 | return true; | |||
2705 | ||||
2706 | // A byval, inalloca may not be null in a non-default addres space. A | |||
2707 | // nonnull argument is assumed never 0. | |||
2708 | if (const Argument *A = dyn_cast<Argument>(V)) { | |||
2709 | if (((A->hasPassPointeeByValueCopyAttr() && | |||
2710 | !NullPointerIsDefined(A->getParent(), PtrTy->getAddressSpace())) || | |||
2711 | A->hasNonNullAttr())) | |||
2712 | return true; | |||
2713 | } | |||
2714 | ||||
2715 | // A Load tagged with nonnull metadata is never null. | |||
2716 | if (const LoadInst *LI = dyn_cast<LoadInst>(V)) | |||
2717 | if (Q.IIQ.getMetadata(LI, LLVMContext::MD_nonnull)) | |||
2718 | return true; | |||
2719 | ||||
2720 | if (const auto *Call = dyn_cast<CallBase>(V)) { | |||
2721 | if (Call->isReturnNonNull()) | |||
2722 | return true; | |||
2723 | if (const auto *RP = getArgumentAliasingToReturnedPointer(Call, true)) | |||
2724 | return isKnownNonZero(RP, Depth, Q); | |||
2725 | } | |||
2726 | } | |||
2727 | ||||
2728 | if (!isa<Constant>(V) && | |||
2729 | isKnownNonNullFromDominatingCondition(V, Q.CxtI, Q.DT)) | |||
2730 | return true; | |||
2731 | ||||
2732 | const Operator *I = dyn_cast<Operator>(V); | |||
2733 | if (!I) | |||
2734 | return false; | |||
2735 | ||||
2736 | unsigned BitWidth = getBitWidth(V->getType()->getScalarType(), Q.DL); | |||
2737 | switch (I->getOpcode()) { | |||
2738 | case Instruction::GetElementPtr: | |||
2739 | if (I->getType()->isPointerTy()) | |||
2740 | return isGEPKnownNonNull(cast<GEPOperator>(I), Depth, Q); | |||
2741 | break; | |||
2742 | case Instruction::BitCast: { | |||
2743 | // We need to be a bit careful here. We can only peek through the bitcast | |||
2744 | // if the scalar size of elements in the operand are smaller than and a | |||
2745 | // multiple of the size they are casting too. Take three cases: | |||
2746 | // | |||
2747 | // 1) Unsafe: | |||
2748 | // bitcast <2 x i16> %NonZero to <4 x i8> | |||
2749 | // | |||
2750 | // %NonZero can have 2 non-zero i16 elements, but isKnownNonZero on a | |||
2751 | // <4 x i8> requires that all 4 i8 elements be non-zero which isn't | |||
2752 | // guranteed (imagine just sign bit set in the 2 i16 elements). | |||
2753 | // | |||
2754 | // 2) Unsafe: | |||
2755 | // bitcast <4 x i3> %NonZero to <3 x i4> | |||
2756 | // | |||
2757 | // Even though the scalar size of the src (`i3`) is smaller than the | |||
2758 | // scalar size of the dst `i4`, because `i3` is not a multiple of `i4` | |||
2759 | // its possible for the `3 x i4` elements to be zero because there are | |||
2760 | // some elements in the destination that don't contain any full src | |||
2761 | // element. | |||
2762 | // | |||
2763 | // 3) Safe: | |||
2764 | // bitcast <4 x i8> %NonZero to <2 x i16> | |||
2765 | // | |||
2766 | // This is always safe as non-zero in the 4 i8 elements implies | |||
2767 | // non-zero in the combination of any two adjacent ones. Since i8 is a | |||
2768 | // multiple of i16, each i16 is guranteed to have 2 full i8 elements. | |||
2769 | // This all implies the 2 i16 elements are non-zero. | |||
2770 | Type *FromTy = I->getOperand(0)->getType(); | |||
2771 | if ((FromTy->isIntOrIntVectorTy() || FromTy->isPtrOrPtrVectorTy()) && | |||
2772 | (BitWidth % getBitWidth(FromTy->getScalarType(), Q.DL)) == 0) | |||
2773 | return isKnownNonZero(I->getOperand(0), Depth, Q); | |||
2774 | } break; | |||
2775 | case Instruction::IntToPtr: | |||
2776 | // Note that we have to take special care to avoid looking through | |||
2777 | // truncating casts, e.g., int2ptr/ptr2int with appropriate sizes, as well | |||
2778 | // as casts that can alter the value, e.g., AddrSpaceCasts. | |||
2779 | if (!isa<ScalableVectorType>(I->getType()) && | |||
2780 | Q.DL.getTypeSizeInBits(I->getOperand(0)->getType()).getFixedValue() <= | |||
2781 | Q.DL.getTypeSizeInBits(I->getType()).getFixedValue()) | |||
2782 | return isKnownNonZero(I->getOperand(0), Depth, Q); | |||
2783 | break; | |||
2784 | case Instruction::PtrToInt: | |||
2785 | // Similar to int2ptr above, we can look through ptr2int here if the cast | |||
2786 | // is a no-op or an extend and not a truncate. | |||
2787 | if (!isa<ScalableVectorType>(I->getType()) && | |||
2788 | Q.DL.getTypeSizeInBits(I->getOperand(0)->getType()).getFixedValue() <= | |||
2789 | Q.DL.getTypeSizeInBits(I->getType()).getFixedValue()) | |||
2790 | return isKnownNonZero(I->getOperand(0), Depth, Q); | |||
2791 | break; | |||
2792 | case Instruction::Sub: | |||
2793 | return isNonZeroSub(DemandedElts, Depth, Q, BitWidth, I->getOperand(0), | |||
2794 | I->getOperand(1)); | |||
2795 | case Instruction::Or: | |||
2796 | // X | Y != 0 if X != 0 or Y != 0. | |||
2797 | return isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q) || | |||
2798 | isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q); | |||
2799 | case Instruction::SExt: | |||
2800 | case Instruction::ZExt: | |||
2801 | // ext X != 0 if X != 0. | |||
2802 | return isKnownNonZero(I->getOperand(0), Depth, Q); | |||
2803 | ||||
2804 | case Instruction::Shl: { | |||
2805 | // shl nsw/nuw can't remove any non-zero bits. | |||
2806 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); | |||
2807 | if (Q.IIQ.hasNoUnsignedWrap(BO) || Q.IIQ.hasNoSignedWrap(BO)) | |||
2808 | return isKnownNonZero(I->getOperand(0), Depth, Q); | |||
2809 | ||||
2810 | // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined | |||
2811 | // if the lowest bit is shifted off the end. | |||
2812 | KnownBits Known(BitWidth); | |||
2813 | computeKnownBits(I->getOperand(0), DemandedElts, Known, Depth, Q); | |||
2814 | if (Known.One[0]) | |||
2815 | return true; | |||
2816 | ||||
2817 | return isNonZeroShift(I, DemandedElts, Depth, Q, Known); | |||
2818 | } | |||
2819 | case Instruction::LShr: | |||
2820 | case Instruction::AShr: { | |||
2821 | // shr exact can only shift out zero bits. | |||
2822 | const PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V); | |||
2823 | if (BO->isExact()) | |||
2824 | return isKnownNonZero(I->getOperand(0), Depth, Q); | |||
2825 | ||||
2826 | // shr X, Y != 0 if X is negative. Note that the value of the shift is not | |||
2827 | // defined if the sign bit is shifted off the end. | |||
2828 | KnownBits Known = | |||
2829 | computeKnownBits(I->getOperand(0), DemandedElts, Depth, Q); | |||
2830 | if (Known.isNegative()) | |||
2831 | return true; | |||
2832 | ||||
2833 | return isNonZeroShift(I, DemandedElts, Depth, Q, Known); | |||
2834 | } | |||
2835 | case Instruction::UDiv: | |||
2836 | case Instruction::SDiv: | |||
2837 | // X / Y | |||
2838 | // div exact can only produce a zero if the dividend is zero. | |||
2839 | if (cast<PossiblyExactOperator>(I)->isExact()) | |||
2840 | return isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q); | |||
2841 | if (I->getOpcode() == Instruction::UDiv) { | |||
2842 | std::optional<bool> XUgeY; | |||
2843 | KnownBits XKnown = | |||
2844 | computeKnownBits(I->getOperand(0), DemandedElts, Depth, Q); | |||
2845 | if (!XKnown.isUnknown()) { | |||
2846 | KnownBits YKnown = | |||
2847 | computeKnownBits(I->getOperand(1), DemandedElts, Depth, Q); | |||
2848 | // If X u>= Y then div is non zero (0/0 is UB). | |||
2849 | XUgeY = KnownBits::uge(XKnown, YKnown); | |||
2850 | } | |||
2851 | // If X is total unknown or X u< Y we won't be able to prove non-zero | |||
2852 | // with compute known bits so just return early. | |||
2853 | return XUgeY && *XUgeY; | |||
2854 | } | |||
2855 | break; | |||
2856 | case Instruction::Add: { | |||
2857 | // X + Y. | |||
2858 | ||||
2859 | // If Add has nuw wrap flag, then if either X or Y is non-zero the result is | |||
2860 | // non-zero. | |||
2861 | auto *BO = cast<OverflowingBinaryOperator>(V); | |||
2862 | if (Q.IIQ.hasNoUnsignedWrap(BO)) | |||
2863 | return isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q) || | |||
2864 | isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q); | |||
2865 | ||||
2866 | return isNonZeroAdd(DemandedElts, Depth, Q, BitWidth, I->getOperand(0), | |||
2867 | I->getOperand(1), Q.IIQ.hasNoSignedWrap(BO)); | |||
2868 | } | |||
2869 | case Instruction::Mul: { | |||
2870 | // If X and Y are non-zero then so is X * Y as long as the multiplication | |||
2871 | // does not overflow. | |||
2872 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); | |||
2873 | if (Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO)) | |||
2874 | return isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q) && | |||
2875 | isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q); | |||
2876 | ||||
2877 | // If either X or Y is odd, then if the other is non-zero the result can't | |||
2878 | // be zero. | |||
2879 | KnownBits XKnown = | |||
2880 | computeKnownBits(I->getOperand(0), DemandedElts, Depth, Q); | |||
2881 | if (XKnown.One[0]) | |||
2882 | return isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q); | |||
2883 | ||||
2884 | KnownBits YKnown = | |||
2885 | computeKnownBits(I->getOperand(1), DemandedElts, Depth, Q); | |||
2886 | if (YKnown.One[0]) | |||
2887 | return XKnown.isNonZero() || | |||
2888 | isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q); | |||
2889 | ||||
2890 | return KnownBits::mul(XKnown, YKnown).isNonZero(); | |||
2891 | } | |||
2892 | case Instruction::Select: | |||
2893 | // (C ? X : Y) != 0 if X != 0 and Y != 0. | |||
2894 | if (isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q) && | |||
2895 | isKnownNonZero(I->getOperand(2), DemandedElts, Depth, Q)) | |||
2896 | return true; | |||
2897 | break; | |||
2898 | case Instruction::PHI: { | |||
2899 | auto *PN = cast<PHINode>(I); | |||
2900 | if (Q.IIQ.UseInstrInfo && isNonZeroRecurrence(PN)) | |||
2901 | return true; | |||
2902 | ||||
2903 | // Check if all incoming values are non-zero using recursion. | |||
2904 | Query RecQ = Q; | |||
2905 | unsigned NewDepth = std::max(Depth, MaxAnalysisRecursionDepth - 1); | |||
2906 | return llvm::all_of(PN->operands(), [&](const Use &U) { | |||
2907 | if (U.get() == PN) | |||
2908 | return true; | |||
2909 | RecQ.CxtI = PN->getIncomingBlock(U)->getTerminator(); | |||
2910 | return isKnownNonZero(U.get(), DemandedElts, NewDepth, RecQ); | |||
2911 | }); | |||
2912 | } | |||
2913 | case Instruction::ExtractElement: | |||
2914 | if (const auto *EEI = dyn_cast<ExtractElementInst>(V)) { | |||
2915 | const Value *Vec = EEI->getVectorOperand(); | |||
2916 | const Value *Idx = EEI->getIndexOperand(); | |||
2917 | auto *CIdx = dyn_cast<ConstantInt>(Idx); | |||
2918 | if (auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType())) { | |||
2919 | unsigned NumElts = VecTy->getNumElements(); | |||
2920 | APInt DemandedVecElts = APInt::getAllOnes(NumElts); | |||
2921 | if (CIdx && CIdx->getValue().ult(NumElts)) | |||
2922 | DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue()); | |||
2923 | return isKnownNonZero(Vec, DemandedVecElts, Depth, Q); | |||
2924 | } | |||
2925 | } | |||
2926 | break; | |||
2927 | case Instruction::Freeze: | |||
2928 | return isKnownNonZero(I->getOperand(0), Depth, Q) && | |||
2929 | isGuaranteedNotToBePoison(I->getOperand(0), Q.AC, Q.CxtI, Q.DT, | |||
2930 | Depth); | |||
2931 | case Instruction::Call: | |||
2932 | if (auto *II = dyn_cast<IntrinsicInst>(I)) { | |||
2933 | switch (II->getIntrinsicID()) { | |||
2934 | case Intrinsic::sshl_sat: | |||
2935 | case Intrinsic::ushl_sat: | |||
2936 | case Intrinsic::abs: | |||
2937 | case Intrinsic::bitreverse: | |||
2938 | case Intrinsic::bswap: | |||
2939 | case Intrinsic::ctpop: | |||
2940 | return isKnownNonZero(II->getArgOperand(0), DemandedElts, Depth, Q); | |||
2941 | case Intrinsic::ssub_sat: | |||
2942 | return isNonZeroSub(DemandedElts, Depth, Q, BitWidth, | |||
2943 | II->getArgOperand(0), II->getArgOperand(1)); | |||
2944 | case Intrinsic::sadd_sat: | |||
2945 | return isNonZeroAdd(DemandedElts, Depth, Q, BitWidth, | |||
2946 | II->getArgOperand(0), II->getArgOperand(1), | |||
2947 | /*NSW*/ true); | |||
2948 | case Intrinsic::umax: | |||
2949 | case Intrinsic::uadd_sat: | |||
2950 | return isKnownNonZero(II->getArgOperand(1), DemandedElts, Depth, Q) || | |||
2951 | isKnownNonZero(II->getArgOperand(0), DemandedElts, Depth, Q); | |||
2952 | case Intrinsic::smin: | |||
2953 | case Intrinsic::smax: { | |||
2954 | auto KnownOpImpliesNonZero = [&](const KnownBits &K) { | |||
2955 | return II->getIntrinsicID() == Intrinsic::smin | |||
2956 | ? K.isNegative() | |||
2957 | : K.isStrictlyPositive(); | |||
2958 | }; | |||
2959 | KnownBits XKnown = | |||
2960 | computeKnownBits(II->getArgOperand(0), DemandedElts, Depth, Q); | |||
2961 | if (KnownOpImpliesNonZero(XKnown)) | |||
2962 | return true; | |||
2963 | KnownBits YKnown = | |||
2964 | computeKnownBits(II->getArgOperand(1), DemandedElts, Depth, Q); | |||
2965 | if (KnownOpImpliesNonZero(YKnown)) | |||
2966 | return true; | |||
2967 | ||||
2968 | if (XKnown.isNonZero() && YKnown.isNonZero()) | |||
2969 | return true; | |||
2970 | } | |||
2971 | [[fallthrough]]; | |||
2972 | case Intrinsic::umin: | |||
2973 | return isKnownNonZero(II->getArgOperand(0), DemandedElts, Depth, Q) && | |||
2974 | isKnownNonZero(II->getArgOperand(1), DemandedElts, Depth, Q); | |||
2975 | case Intrinsic::cttz: | |||
2976 | return computeKnownBits(II->getArgOperand(0), DemandedElts, Depth, Q) | |||
2977 | .Zero[0]; | |||
2978 | case Intrinsic::ctlz: | |||
2979 | return computeKnownBits(II->getArgOperand(0), DemandedElts, Depth, Q) | |||
2980 | .isNonNegative(); | |||
2981 | case Intrinsic::fshr: | |||
2982 | case Intrinsic::fshl: | |||
2983 | // If Op0 == Op1, this is a rotate. rotate(x, y) != 0 iff x != 0. | |||
2984 | if (II->getArgOperand(0) == II->getArgOperand(1)) | |||
2985 | return isKnownNonZero(II->getArgOperand(0), DemandedElts, Depth, Q); | |||
2986 | break; | |||
2987 | case Intrinsic::vscale: | |||
2988 | return true; | |||
2989 | default: | |||
2990 | break; | |||
2991 | } | |||
2992 | } | |||
2993 | break; | |||
2994 | } | |||
2995 | ||||
2996 | KnownBits Known(BitWidth); | |||
2997 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
2998 | return Known.One != 0; | |||
2999 | } | |||
3000 | ||||
3001 | bool isKnownNonZero(const Value* V, unsigned Depth, const Query& Q) { | |||
3002 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
3003 | APInt DemandedElts = | |||
3004 | FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1); | |||
3005 | return isKnownNonZero(V, DemandedElts, Depth, Q); | |||
3006 | } | |||
3007 | ||||
3008 | /// If the pair of operators are the same invertible function, return the | |||
3009 | /// the operands of the function corresponding to each input. Otherwise, | |||
3010 | /// return std::nullopt. An invertible function is one that is 1-to-1 and maps | |||
3011 | /// every input value to exactly one output value. This is equivalent to | |||
3012 | /// saying that Op1 and Op2 are equal exactly when the specified pair of | |||
3013 | /// operands are equal, (except that Op1 and Op2 may be poison more often.) | |||
3014 | static std::optional<std::pair<Value*, Value*>> | |||
3015 | getInvertibleOperands(const Operator *Op1, | |||
3016 | const Operator *Op2) { | |||
3017 | if (Op1->getOpcode() != Op2->getOpcode()) | |||
3018 | return std::nullopt; | |||
3019 | ||||
3020 | auto getOperands = [&](unsigned OpNum) -> auto { | |||
3021 | return std::make_pair(Op1->getOperand(OpNum), Op2->getOperand(OpNum)); | |||
3022 | }; | |||
3023 | ||||
3024 | switch (Op1->getOpcode()) { | |||
3025 | default: | |||
3026 | break; | |||
3027 | case Instruction::Add: | |||
3028 | case Instruction::Sub: | |||
3029 | if (Op1->getOperand(0) == Op2->getOperand(0)) | |||
3030 | return getOperands(1); | |||
3031 | if (Op1->getOperand(1) == Op2->getOperand(1)) | |||
3032 | return getOperands(0); | |||
3033 | break; | |||
3034 | case Instruction::Mul: { | |||
3035 | // invertible if A * B == (A * B) mod 2^N where A, and B are integers | |||
3036 | // and N is the bitwdith. The nsw case is non-obvious, but proven by | |||
3037 | // alive2: https://alive2.llvm.org/ce/z/Z6D5qK | |||
3038 | auto *OBO1 = cast<OverflowingBinaryOperator>(Op1); | |||
3039 | auto *OBO2 = cast<OverflowingBinaryOperator>(Op2); | |||
3040 | if ((!OBO1->hasNoUnsignedWrap() || !OBO2->hasNoUnsignedWrap()) && | |||
3041 | (!OBO1->hasNoSignedWrap() || !OBO2->hasNoSignedWrap())) | |||
3042 | break; | |||
3043 | ||||
3044 | // Assume operand order has been canonicalized | |||
3045 | if (Op1->getOperand(1) == Op2->getOperand(1) && | |||
3046 | isa<ConstantInt>(Op1->getOperand(1)) && | |||
3047 | !cast<ConstantInt>(Op1->getOperand(1))->isZero()) | |||
3048 | return getOperands(0); | |||
3049 | break; | |||
3050 | } | |||
3051 | case Instruction::Shl: { | |||
3052 | // Same as multiplies, with the difference that we don't need to check | |||
3053 | // for a non-zero multiply. Shifts always multiply by non-zero. | |||
3054 | auto *OBO1 = cast<OverflowingBinaryOperator>(Op1); | |||
3055 | auto *OBO2 = cast<OverflowingBinaryOperator>(Op2); | |||
3056 | if ((!OBO1->hasNoUnsignedWrap() || !OBO2->hasNoUnsignedWrap()) && | |||
3057 | (!OBO1->hasNoSignedWrap() || !OBO2->hasNoSignedWrap())) | |||
3058 | break; | |||
3059 | ||||
3060 | if (Op1->getOperand(1) == Op2->getOperand(1)) | |||
3061 | return getOperands(0); | |||
3062 | break; | |||
3063 | } | |||
3064 | case Instruction::AShr: | |||
3065 | case Instruction::LShr: { | |||
3066 | auto *PEO1 = cast<PossiblyExactOperator>(Op1); | |||
3067 | auto *PEO2 = cast<PossiblyExactOperator>(Op2); | |||
3068 | if (!PEO1->isExact() || !PEO2->isExact()) | |||
3069 | break; | |||
3070 | ||||
3071 | if (Op1->getOperand(1) == Op2->getOperand(1)) | |||
3072 | return getOperands(0); | |||
3073 | break; | |||
3074 | } | |||
3075 | case Instruction::SExt: | |||
3076 | case Instruction::ZExt: | |||
3077 | if (Op1->getOperand(0)->getType() == Op2->getOperand(0)->getType()) | |||
3078 | return getOperands(0); | |||
3079 | break; | |||
3080 | case Instruction::PHI: { | |||
3081 | const PHINode *PN1 = cast<PHINode>(Op1); | |||
3082 | const PHINode *PN2 = cast<PHINode>(Op2); | |||
3083 | ||||
3084 | // If PN1 and PN2 are both recurrences, can we prove the entire recurrences | |||
3085 | // are a single invertible function of the start values? Note that repeated | |||
3086 | // application of an invertible function is also invertible | |||
3087 | BinaryOperator *BO1 = nullptr; | |||
3088 | Value *Start1 = nullptr, *Step1 = nullptr; | |||
3089 | BinaryOperator *BO2 = nullptr; | |||
3090 | Value *Start2 = nullptr, *Step2 = nullptr; | |||
3091 | if (PN1->getParent() != PN2->getParent() || | |||
3092 | !matchSimpleRecurrence(PN1, BO1, Start1, Step1) || | |||
3093 | !matchSimpleRecurrence(PN2, BO2, Start2, Step2)) | |||
3094 | break; | |||
3095 | ||||
3096 | auto Values = getInvertibleOperands(cast<Operator>(BO1), | |||
3097 | cast<Operator>(BO2)); | |||
3098 | if (!Values) | |||
3099 | break; | |||
3100 | ||||
3101 | // We have to be careful of mutually defined recurrences here. Ex: | |||
3102 | // * X_i = X_(i-1) OP Y_(i-1), and Y_i = X_(i-1) OP V | |||
3103 | // * X_i = Y_i = X_(i-1) OP Y_(i-1) | |||
3104 | // The invertibility of these is complicated, and not worth reasoning | |||
3105 | // about (yet?). | |||
3106 | if (Values->first != PN1 || Values->second != PN2) | |||
3107 | break; | |||
3108 | ||||
3109 | return std::make_pair(Start1, Start2); | |||
3110 | } | |||
3111 | } | |||
3112 | return std::nullopt; | |||
3113 | } | |||
3114 | ||||
3115 | /// Return true if V2 == V1 + X, where X is known non-zero. | |||
3116 | static bool isAddOfNonZero(const Value *V1, const Value *V2, unsigned Depth, | |||
3117 | const Query &Q) { | |||
3118 | const BinaryOperator *BO = dyn_cast<BinaryOperator>(V1); | |||
3119 | if (!BO || BO->getOpcode() != Instruction::Add) | |||
3120 | return false; | |||
3121 | Value *Op = nullptr; | |||
3122 | if (V2 == BO->getOperand(0)) | |||
3123 | Op = BO->getOperand(1); | |||
3124 | else if (V2 == BO->getOperand(1)) | |||
3125 | Op = BO->getOperand(0); | |||
3126 | else | |||
3127 | return false; | |||
3128 | return isKnownNonZero(Op, Depth + 1, Q); | |||
3129 | } | |||
3130 | ||||
3131 | /// Return true if V2 == V1 * C, where V1 is known non-zero, C is not 0/1 and | |||
3132 | /// the multiplication is nuw or nsw. | |||
3133 | static bool isNonEqualMul(const Value *V1, const Value *V2, unsigned Depth, | |||
3134 | const Query &Q) { | |||
3135 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) { | |||
3136 | const APInt *C; | |||
3137 | return match(OBO, m_Mul(m_Specific(V1), m_APInt(C))) && | |||
3138 | (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) && | |||
3139 | !C->isZero() && !C->isOne() && isKnownNonZero(V1, Depth + 1, Q); | |||
3140 | } | |||
3141 | return false; | |||
3142 | } | |||
3143 | ||||
3144 | /// Return true if V2 == V1 << C, where V1 is known non-zero, C is not 0 and | |||
3145 | /// the shift is nuw or nsw. | |||
3146 | static bool isNonEqualShl(const Value *V1, const Value *V2, unsigned Depth, | |||
3147 | const Query &Q) { | |||
3148 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) { | |||
3149 | const APInt *C; | |||
3150 | return match(OBO, m_Shl(m_Specific(V1), m_APInt(C))) && | |||
3151 | (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) && | |||
3152 | !C->isZero() && isKnownNonZero(V1, Depth + 1, Q); | |||
3153 | } | |||
3154 | return false; | |||
3155 | } | |||
3156 | ||||
3157 | static bool isNonEqualPHIs(const PHINode *PN1, const PHINode *PN2, | |||
3158 | unsigned Depth, const Query &Q) { | |||
3159 | // Check two PHIs are in same block. | |||
3160 | if (PN1->getParent() != PN2->getParent()) | |||
3161 | return false; | |||
3162 | ||||
3163 | SmallPtrSet<const BasicBlock *, 8> VisitedBBs; | |||
3164 | bool UsedFullRecursion = false; | |||
3165 | for (const BasicBlock *IncomBB : PN1->blocks()) { | |||
3166 | if (!VisitedBBs.insert(IncomBB).second) | |||
3167 | continue; // Don't reprocess blocks that we have dealt with already. | |||
3168 | const Value *IV1 = PN1->getIncomingValueForBlock(IncomBB); | |||
3169 | const Value *IV2 = PN2->getIncomingValueForBlock(IncomBB); | |||
3170 | const APInt *C1, *C2; | |||
3171 | if (match(IV1, m_APInt(C1)) && match(IV2, m_APInt(C2)) && *C1 != *C2) | |||
3172 | continue; | |||
3173 | ||||
3174 | // Only one pair of phi operands is allowed for full recursion. | |||
3175 | if (UsedFullRecursion) | |||
3176 | return false; | |||
3177 | ||||
3178 | Query RecQ = Q; | |||
3179 | RecQ.CxtI = IncomBB->getTerminator(); | |||
3180 | if (!isKnownNonEqual(IV1, IV2, Depth + 1, RecQ)) | |||
3181 | return false; | |||
3182 | UsedFullRecursion = true; | |||
3183 | } | |||
3184 | return true; | |||
3185 | } | |||
3186 | ||||
3187 | /// Return true if it is known that V1 != V2. | |||
3188 | static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth, | |||
3189 | const Query &Q) { | |||
3190 | if (V1 == V2) | |||
3191 | return false; | |||
3192 | if (V1->getType() != V2->getType()) | |||
3193 | // We can't look through casts yet. | |||
3194 | return false; | |||
3195 | ||||
3196 | if (Depth >= MaxAnalysisRecursionDepth) | |||
3197 | return false; | |||
3198 | ||||
3199 | // See if we can recurse through (exactly one of) our operands. This | |||
3200 | // requires our operation be 1-to-1 and map every input value to exactly | |||
3201 | // one output value. Such an operation is invertible. | |||
3202 | auto *O1 = dyn_cast<Operator>(V1); | |||
3203 | auto *O2 = dyn_cast<Operator>(V2); | |||
3204 | if (O1 && O2 && O1->getOpcode() == O2->getOpcode()) { | |||
3205 | if (auto Values = getInvertibleOperands(O1, O2)) | |||
3206 | return isKnownNonEqual(Values->first, Values->second, Depth + 1, Q); | |||
3207 | ||||
3208 | if (const PHINode *PN1 = dyn_cast<PHINode>(V1)) { | |||
3209 | const PHINode *PN2 = cast<PHINode>(V2); | |||
3210 | // FIXME: This is missing a generalization to handle the case where one is | |||
3211 | // a PHI and another one isn't. | |||
3212 | if (isNonEqualPHIs(PN1, PN2, Depth, Q)) | |||
3213 | return true; | |||
3214 | }; | |||
3215 | } | |||
3216 | ||||
3217 | if (isAddOfNonZero(V1, V2, Depth, Q) || isAddOfNonZero(V2, V1, Depth, Q)) | |||
3218 | return true; | |||
3219 | ||||
3220 | if (isNonEqualMul(V1, V2, Depth, Q) || isNonEqualMul(V2, V1, Depth, Q)) | |||
3221 | return true; | |||
3222 | ||||
3223 | if (isNonEqualShl(V1, V2, Depth, Q) || isNonEqualShl(V2, V1, Depth, Q)) | |||
3224 | return true; | |||
3225 | ||||
3226 | if (V1->getType()->isIntOrIntVectorTy()) { | |||
3227 | // Are any known bits in V1 contradictory to known bits in V2? If V1 | |||
3228 | // has a known zero where V2 has a known one, they must not be equal. | |||
3229 | KnownBits Known1 = computeKnownBits(V1, Depth, Q); | |||
3230 | KnownBits Known2 = computeKnownBits(V2, Depth, Q); | |||
3231 | ||||
3232 | if (Known1.Zero.intersects(Known2.One) || | |||
3233 | Known2.Zero.intersects(Known1.One)) | |||
3234 | return true; | |||
3235 | } | |||
3236 | return false; | |||
3237 | } | |||
3238 | ||||
3239 | /// Return true if 'V & Mask' is known to be zero. We use this predicate to | |||
3240 | /// simplify operations downstream. Mask is known to be zero for bits that V | |||
3241 | /// cannot have. | |||
3242 | /// | |||
3243 | /// This function is defined on values with integer type, values with pointer | |||
3244 | /// type, and vectors of integers. In the case | |||
3245 | /// where V is a vector, the mask, known zero, and known one values are the | |||
3246 | /// same width as the vector element, and the bit is set only if it is true | |||
3247 | /// for all of the elements in the vector. | |||
3248 | bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, | |||
3249 | const Query &Q) { | |||
3250 | KnownBits Known(Mask.getBitWidth()); | |||
3251 | computeKnownBits(V, Known, Depth, Q); | |||
3252 | return Mask.isSubsetOf(Known.Zero); | |||
3253 | } | |||
3254 | ||||
3255 | // Match a signed min+max clamp pattern like smax(smin(In, CHigh), CLow). | |||
3256 | // Returns the input and lower/upper bounds. | |||
3257 | static bool isSignedMinMaxClamp(const Value *Select, const Value *&In, | |||
3258 | const APInt *&CLow, const APInt *&CHigh) { | |||
3259 | assert(isa<Operator>(Select) &&(static_cast <bool> (isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction:: Select && "Input should be a Select!") ? void (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3261, __extension__ __PRETTY_FUNCTION__ )) | |||
3260 | cast<Operator>(Select)->getOpcode() == Instruction::Select &&(static_cast <bool> (isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction:: Select && "Input should be a Select!") ? void (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3261, __extension__ __PRETTY_FUNCTION__ )) | |||
3261 | "Input should be a Select!")(static_cast <bool> (isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction:: Select && "Input should be a Select!") ? void (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3261, __extension__ __PRETTY_FUNCTION__ )); | |||
3262 | ||||
3263 | const Value *LHS = nullptr, *RHS = nullptr; | |||
3264 | SelectPatternFlavor SPF = matchSelectPattern(Select, LHS, RHS).Flavor; | |||
3265 | if (SPF != SPF_SMAX && SPF != SPF_SMIN) | |||
3266 | return false; | |||
3267 | ||||
3268 | if (!match(RHS, m_APInt(CLow))) | |||
3269 | return false; | |||
3270 | ||||
3271 | const Value *LHS2 = nullptr, *RHS2 = nullptr; | |||
3272 | SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor; | |||
3273 | if (getInverseMinMaxFlavor(SPF) != SPF2) | |||
3274 | return false; | |||
3275 | ||||
3276 | if (!match(RHS2, m_APInt(CHigh))) | |||
3277 | return false; | |||
3278 | ||||
3279 | if (SPF == SPF_SMIN) | |||
3280 | std::swap(CLow, CHigh); | |||
3281 | ||||
3282 | In = LHS2; | |||
3283 | return CLow->sle(*CHigh); | |||
3284 | } | |||
3285 | ||||
3286 | static bool isSignedMinMaxIntrinsicClamp(const IntrinsicInst *II, | |||
3287 | const APInt *&CLow, | |||
3288 | const APInt *&CHigh) { | |||
3289 | assert((II->getIntrinsicID() == Intrinsic::smin ||(static_cast <bool> ((II->getIntrinsicID() == Intrinsic ::smin || II->getIntrinsicID() == Intrinsic::smax) && "Must be smin/smax") ? void (0) : __assert_fail ("(II->getIntrinsicID() == Intrinsic::smin || II->getIntrinsicID() == Intrinsic::smax) && \"Must be smin/smax\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3290, __extension__ __PRETTY_FUNCTION__ )) | |||
3290 | II->getIntrinsicID() == Intrinsic::smax) && "Must be smin/smax")(static_cast <bool> ((II->getIntrinsicID() == Intrinsic ::smin || II->getIntrinsicID() == Intrinsic::smax) && "Must be smin/smax") ? void (0) : __assert_fail ("(II->getIntrinsicID() == Intrinsic::smin || II->getIntrinsicID() == Intrinsic::smax) && \"Must be smin/smax\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3290, __extension__ __PRETTY_FUNCTION__ )); | |||
3291 | ||||
3292 | Intrinsic::ID InverseID = getInverseMinMaxIntrinsic(II->getIntrinsicID()); | |||
3293 | auto *InnerII = dyn_cast<IntrinsicInst>(II->getArgOperand(0)); | |||
3294 | if (!InnerII || InnerII->getIntrinsicID() != InverseID || | |||
3295 | !match(II->getArgOperand(1), m_APInt(CLow)) || | |||
3296 | !match(InnerII->getArgOperand(1), m_APInt(CHigh))) | |||
3297 | return false; | |||
3298 | ||||
3299 | if (II->getIntrinsicID() == Intrinsic::smin) | |||
3300 | std::swap(CLow, CHigh); | |||
3301 | return CLow->sle(*CHigh); | |||
3302 | } | |||
3303 | ||||
3304 | /// For vector constants, loop over the elements and find the constant with the | |||
3305 | /// minimum number of sign bits. Return 0 if the value is not a vector constant | |||
3306 | /// or if any element was not analyzed; otherwise, return the count for the | |||
3307 | /// element with the minimum number of sign bits. | |||
3308 | static unsigned computeNumSignBitsVectorConstant(const Value *V, | |||
3309 | const APInt &DemandedElts, | |||
3310 | unsigned TyBits) { | |||
3311 | const auto *CV = dyn_cast<Constant>(V); | |||
3312 | if (!CV || !isa<FixedVectorType>(CV->getType())) | |||
3313 | return 0; | |||
3314 | ||||
3315 | unsigned MinSignBits = TyBits; | |||
3316 | unsigned NumElts = cast<FixedVectorType>(CV->getType())->getNumElements(); | |||
3317 | for (unsigned i = 0; i != NumElts; ++i) { | |||
3318 | if (!DemandedElts[i]) | |||
3319 | continue; | |||
3320 | // If we find a non-ConstantInt, bail out. | |||
3321 | auto *Elt = dyn_cast_or_null<ConstantInt>(CV->getAggregateElement(i)); | |||
3322 | if (!Elt) | |||
3323 | return 0; | |||
3324 | ||||
3325 | MinSignBits = std::min(MinSignBits, Elt->getValue().getNumSignBits()); | |||
3326 | } | |||
3327 | ||||
3328 | return MinSignBits; | |||
3329 | } | |||
3330 | ||||
3331 | static unsigned ComputeNumSignBitsImpl(const Value *V, | |||
3332 | const APInt &DemandedElts, | |||
3333 | unsigned Depth, const Query &Q); | |||
3334 | ||||
3335 | static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts, | |||
3336 | unsigned Depth, const Query &Q) { | |||
3337 | unsigned Result = ComputeNumSignBitsImpl(V, DemandedElts, Depth, Q); | |||
3338 | assert(Result > 0 && "At least one sign bit needs to be present!")(static_cast <bool> (Result > 0 && "At least one sign bit needs to be present!" ) ? void (0) : __assert_fail ("Result > 0 && \"At least one sign bit needs to be present!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3338, __extension__ __PRETTY_FUNCTION__ )); | |||
3339 | return Result; | |||
3340 | } | |||
3341 | ||||
3342 | /// Return the number of times the sign bit of the register is replicated into | |||
3343 | /// the other bits. We know that at least 1 bit is always equal to the sign bit | |||
3344 | /// (itself), but other cases can give us information. For example, immediately | |||
3345 | /// after an "ashr X, 2", we know that the top 3 bits are all equal to each | |||
3346 | /// other, so we return 3. For vectors, return the number of sign bits for the | |||
3347 | /// vector element with the minimum number of known sign bits of the demanded | |||
3348 | /// elements in the vector specified by DemandedElts. | |||
3349 | static unsigned ComputeNumSignBitsImpl(const Value *V, | |||
3350 | const APInt &DemandedElts, | |||
3351 | unsigned Depth, const Query &Q) { | |||
3352 | Type *Ty = V->getType(); | |||
3353 | #ifndef NDEBUG | |||
3354 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3354, __extension__ __PRETTY_FUNCTION__ )); | |||
3355 | ||||
3356 | if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) { | |||
3357 | assert((static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3359, __extension__ __PRETTY_FUNCTION__ )) | |||
3358 | FVTy->getNumElements() == DemandedElts.getBitWidth() &&(static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3359, __extension__ __PRETTY_FUNCTION__ )) | |||
3359 | "DemandedElt width should equal the fixed vector number of elements")(static_cast <bool> (FVTy->getNumElements() == DemandedElts .getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3359, __extension__ __PRETTY_FUNCTION__ )); | |||
3360 | } else { | |||
3361 | assert(DemandedElts == APInt(1, 1) &&(static_cast <bool> (DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3362, __extension__ __PRETTY_FUNCTION__ )) | |||
3362 | "DemandedElt width should be 1 for scalars")(static_cast <bool> (DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3362, __extension__ __PRETTY_FUNCTION__ )); | |||
3363 | } | |||
3364 | #endif | |||
3365 | ||||
3366 | // We return the minimum number of sign bits that are guaranteed to be present | |||
3367 | // in V, so for undef we have to conservatively return 1. We don't have the | |||
3368 | // same behavior for poison though -- that's a FIXME today. | |||
3369 | ||||
3370 | Type *ScalarTy = Ty->getScalarType(); | |||
3371 | unsigned TyBits = ScalarTy->isPointerTy() ? | |||
3372 | Q.DL.getPointerTypeSizeInBits(ScalarTy) : | |||
3373 | Q.DL.getTypeSizeInBits(ScalarTy); | |||
3374 | ||||
3375 | unsigned Tmp, Tmp2; | |||
3376 | unsigned FirstAnswer = 1; | |||
3377 | ||||
3378 | // Note that ConstantInt is handled by the general computeKnownBits case | |||
3379 | // below. | |||
3380 | ||||
3381 | if (Depth == MaxAnalysisRecursionDepth) | |||
3382 | return 1; | |||
3383 | ||||
3384 | if (auto *U = dyn_cast<Operator>(V)) { | |||
3385 | switch (Operator::getOpcode(V)) { | |||
3386 | default: break; | |||
3387 | case Instruction::SExt: | |||
3388 | Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); | |||
3389 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q) + Tmp; | |||
3390 | ||||
3391 | case Instruction::SDiv: { | |||
3392 | const APInt *Denominator; | |||
3393 | // sdiv X, C -> adds log(C) sign bits. | |||
3394 | if (match(U->getOperand(1), m_APInt(Denominator))) { | |||
3395 | ||||
3396 | // Ignore non-positive denominator. | |||
3397 | if (!Denominator->isStrictlyPositive()) | |||
3398 | break; | |||
3399 | ||||
3400 | // Calculate the incoming numerator bits. | |||
3401 | unsigned NumBits = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3402 | ||||
3403 | // Add floor(log(C)) bits to the numerator bits. | |||
3404 | return std::min(TyBits, NumBits + Denominator->logBase2()); | |||
3405 | } | |||
3406 | break; | |||
3407 | } | |||
3408 | ||||
3409 | case Instruction::SRem: { | |||
3410 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3411 | ||||
3412 | const APInt *Denominator; | |||
3413 | // srem X, C -> we know that the result is within [-C+1,C) when C is a | |||
3414 | // positive constant. This let us put a lower bound on the number of sign | |||
3415 | // bits. | |||
3416 | if (match(U->getOperand(1), m_APInt(Denominator))) { | |||
3417 | ||||
3418 | // Ignore non-positive denominator. | |||
3419 | if (Denominator->isStrictlyPositive()) { | |||
3420 | // Calculate the leading sign bit constraints by examining the | |||
3421 | // denominator. Given that the denominator is positive, there are two | |||
3422 | // cases: | |||
3423 | // | |||
3424 | // 1. The numerator is positive. The result range is [0,C) and | |||
3425 | // [0,C) u< (1 << ceilLogBase2(C)). | |||
3426 | // | |||
3427 | // 2. The numerator is negative. Then the result range is (-C,0] and | |||
3428 | // integers in (-C,0] are either 0 or >u (-1 << ceilLogBase2(C)). | |||
3429 | // | |||
3430 | // Thus a lower bound on the number of sign bits is `TyBits - | |||
3431 | // ceilLogBase2(C)`. | |||
3432 | ||||
3433 | unsigned ResBits = TyBits - Denominator->ceilLogBase2(); | |||
3434 | Tmp = std::max(Tmp, ResBits); | |||
3435 | } | |||
3436 | } | |||
3437 | return Tmp; | |||
3438 | } | |||
3439 | ||||
3440 | case Instruction::AShr: { | |||
3441 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3442 | // ashr X, C -> adds C sign bits. Vectors too. | |||
3443 | const APInt *ShAmt; | |||
3444 | if (match(U->getOperand(1), m_APInt(ShAmt))) { | |||
3445 | if (ShAmt->uge(TyBits)) | |||
3446 | break; // Bad shift. | |||
3447 | unsigned ShAmtLimited = ShAmt->getZExtValue(); | |||
3448 | Tmp += ShAmtLimited; | |||
3449 | if (Tmp > TyBits) Tmp = TyBits; | |||
3450 | } | |||
3451 | return Tmp; | |||
3452 | } | |||
3453 | case Instruction::Shl: { | |||
3454 | const APInt *ShAmt; | |||
3455 | if (match(U->getOperand(1), m_APInt(ShAmt))) { | |||
3456 | // shl destroys sign bits. | |||
3457 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3458 | if (ShAmt->uge(TyBits) || // Bad shift. | |||
3459 | ShAmt->uge(Tmp)) break; // Shifted all sign bits out. | |||
3460 | Tmp2 = ShAmt->getZExtValue(); | |||
3461 | return Tmp - Tmp2; | |||
3462 | } | |||
3463 | break; | |||
3464 | } | |||
3465 | case Instruction::And: | |||
3466 | case Instruction::Or: | |||
3467 | case Instruction::Xor: // NOT is handled here. | |||
3468 | // Logical binary ops preserve the number of sign bits at the worst. | |||
3469 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3470 | if (Tmp != 1) { | |||
3471 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3472 | FirstAnswer = std::min(Tmp, Tmp2); | |||
3473 | // We computed what we know about the sign bits as our first | |||
3474 | // answer. Now proceed to the generic code that uses | |||
3475 | // computeKnownBits, and pick whichever answer is better. | |||
3476 | } | |||
3477 | break; | |||
3478 | ||||
3479 | case Instruction::Select: { | |||
3480 | // If we have a clamp pattern, we know that the number of sign bits will | |||
3481 | // be the minimum of the clamp min/max range. | |||
3482 | const Value *X; | |||
3483 | const APInt *CLow, *CHigh; | |||
3484 | if (isSignedMinMaxClamp(U, X, CLow, CHigh)) | |||
3485 | return std::min(CLow->getNumSignBits(), CHigh->getNumSignBits()); | |||
3486 | ||||
3487 | Tmp = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3488 | if (Tmp == 1) break; | |||
3489 | Tmp2 = ComputeNumSignBits(U->getOperand(2), Depth + 1, Q); | |||
3490 | return std::min(Tmp, Tmp2); | |||
3491 | } | |||
3492 | ||||
3493 | case Instruction::Add: | |||
3494 | // Add can have at most one carry bit. Thus we know that the output | |||
3495 | // is, at worst, one more bit than the inputs. | |||
3496 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3497 | if (Tmp == 1) break; | |||
3498 | ||||
3499 | // Special case decrementing a value (ADD X, -1): | |||
3500 | if (const auto *CRHS = dyn_cast<Constant>(U->getOperand(1))) | |||
3501 | if (CRHS->isAllOnesValue()) { | |||
3502 | KnownBits Known(TyBits); | |||
3503 | computeKnownBits(U->getOperand(0), Known, Depth + 1, Q); | |||
3504 | ||||
3505 | // If the input is known to be 0 or 1, the output is 0/-1, which is | |||
3506 | // all sign bits set. | |||
3507 | if ((Known.Zero | 1).isAllOnes()) | |||
3508 | return TyBits; | |||
3509 | ||||
3510 | // If we are subtracting one from a positive number, there is no carry | |||
3511 | // out of the result. | |||
3512 | if (Known.isNonNegative()) | |||
3513 | return Tmp; | |||
3514 | } | |||
3515 | ||||
3516 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3517 | if (Tmp2 == 1) break; | |||
3518 | return std::min(Tmp, Tmp2) - 1; | |||
3519 | ||||
3520 | case Instruction::Sub: | |||
3521 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3522 | if (Tmp2 == 1) break; | |||
3523 | ||||
3524 | // Handle NEG. | |||
3525 | if (const auto *CLHS = dyn_cast<Constant>(U->getOperand(0))) | |||
3526 | if (CLHS->isNullValue()) { | |||
3527 | KnownBits Known(TyBits); | |||
3528 | computeKnownBits(U->getOperand(1), Known, Depth + 1, Q); | |||
3529 | // If the input is known to be 0 or 1, the output is 0/-1, which is | |||
3530 | // all sign bits set. | |||
3531 | if ((Known.Zero | 1).isAllOnes()) | |||
3532 | return TyBits; | |||
3533 | ||||
3534 | // If the input is known to be positive (the sign bit is known clear), | |||
3535 | // the output of the NEG has the same number of sign bits as the | |||
3536 | // input. | |||
3537 | if (Known.isNonNegative()) | |||
3538 | return Tmp2; | |||
3539 | ||||
3540 | // Otherwise, we treat this like a SUB. | |||
3541 | } | |||
3542 | ||||
3543 | // Sub can have at most one carry bit. Thus we know that the output | |||
3544 | // is, at worst, one more bit than the inputs. | |||
3545 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3546 | if (Tmp == 1) break; | |||
3547 | return std::min(Tmp, Tmp2) - 1; | |||
3548 | ||||
3549 | case Instruction::Mul: { | |||
3550 | // The output of the Mul can be at most twice the valid bits in the | |||
3551 | // inputs. | |||
3552 | unsigned SignBitsOp0 = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3553 | if (SignBitsOp0 == 1) break; | |||
3554 | unsigned SignBitsOp1 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3555 | if (SignBitsOp1 == 1) break; | |||
3556 | unsigned OutValidBits = | |||
3557 | (TyBits - SignBitsOp0 + 1) + (TyBits - SignBitsOp1 + 1); | |||
3558 | return OutValidBits > TyBits ? 1 : TyBits - OutValidBits + 1; | |||
3559 | } | |||
3560 | ||||
3561 | case Instruction::PHI: { | |||
3562 | const PHINode *PN = cast<PHINode>(U); | |||
3563 | unsigned NumIncomingValues = PN->getNumIncomingValues(); | |||
3564 | // Don't analyze large in-degree PHIs. | |||
3565 | if (NumIncomingValues > 4) break; | |||
3566 | // Unreachable blocks may have zero-operand PHI nodes. | |||
3567 | if (NumIncomingValues == 0) break; | |||
3568 | ||||
3569 | // Take the minimum of all incoming values. This can't infinitely loop | |||
3570 | // because of our depth threshold. | |||
3571 | Query RecQ = Q; | |||
3572 | Tmp = TyBits; | |||
3573 | for (unsigned i = 0, e = NumIncomingValues; i != e; ++i) { | |||
3574 | if (Tmp == 1) return Tmp; | |||
3575 | RecQ.CxtI = PN->getIncomingBlock(i)->getTerminator(); | |||
3576 | Tmp = std::min( | |||
3577 | Tmp, ComputeNumSignBits(PN->getIncomingValue(i), Depth + 1, RecQ)); | |||
3578 | } | |||
3579 | return Tmp; | |||
3580 | } | |||
3581 | ||||
3582 | case Instruction::Trunc: { | |||
3583 | // If the input contained enough sign bits that some remain after the | |||
3584 | // truncation, then we can make use of that. Otherwise we don't know | |||
3585 | // anything. | |||
3586 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3587 | unsigned OperandTyBits = U->getOperand(0)->getType()->getScalarSizeInBits(); | |||
3588 | if (Tmp > (OperandTyBits - TyBits)) | |||
3589 | return Tmp - (OperandTyBits - TyBits); | |||
3590 | ||||
3591 | return 1; | |||
3592 | } | |||
3593 | ||||
3594 | case Instruction::ExtractElement: | |||
3595 | // Look through extract element. At the moment we keep this simple and | |||
3596 | // skip tracking the specific element. But at least we might find | |||
3597 | // information valid for all elements of the vector (for example if vector | |||
3598 | // is sign extended, shifted, etc). | |||
3599 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3600 | ||||
3601 | case Instruction::ShuffleVector: { | |||
3602 | // Collect the minimum number of sign bits that are shared by every vector | |||
3603 | // element referenced by the shuffle. | |||
3604 | auto *Shuf = dyn_cast<ShuffleVectorInst>(U); | |||
3605 | if (!Shuf) { | |||
3606 | // FIXME: Add support for shufflevector constant expressions. | |||
3607 | return 1; | |||
3608 | } | |||
3609 | APInt DemandedLHS, DemandedRHS; | |||
3610 | // For undef elements, we don't know anything about the common state of | |||
3611 | // the shuffle result. | |||
3612 | if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) | |||
3613 | return 1; | |||
3614 | Tmp = std::numeric_limits<unsigned>::max(); | |||
3615 | if (!!DemandedLHS) { | |||
3616 | const Value *LHS = Shuf->getOperand(0); | |||
3617 | Tmp = ComputeNumSignBits(LHS, DemandedLHS, Depth + 1, Q); | |||
3618 | } | |||
3619 | // If we don't know anything, early out and try computeKnownBits | |||
3620 | // fall-back. | |||
3621 | if (Tmp == 1) | |||
3622 | break; | |||
3623 | if (!!DemandedRHS) { | |||
3624 | const Value *RHS = Shuf->getOperand(1); | |||
3625 | Tmp2 = ComputeNumSignBits(RHS, DemandedRHS, Depth + 1, Q); | |||
3626 | Tmp = std::min(Tmp, Tmp2); | |||
3627 | } | |||
3628 | // If we don't know anything, early out and try computeKnownBits | |||
3629 | // fall-back. | |||
3630 | if (Tmp == 1) | |||
3631 | break; | |||
3632 | assert(Tmp <= TyBits && "Failed to determine minimum sign bits")(static_cast <bool> (Tmp <= TyBits && "Failed to determine minimum sign bits" ) ? void (0) : __assert_fail ("Tmp <= TyBits && \"Failed to determine minimum sign bits\"" , "llvm/lib/Analysis/ValueTracking.cpp", 3632, __extension__ __PRETTY_FUNCTION__ )); | |||
3633 | return Tmp; | |||
3634 | } | |||
3635 | case Instruction::Call: { | |||
3636 | if (const auto *II = dyn_cast<IntrinsicInst>(U)) { | |||
3637 | switch (II->getIntrinsicID()) { | |||
3638 | default: break; | |||
3639 | case Intrinsic::abs: | |||
3640 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3641 | if (Tmp == 1) break; | |||
3642 | ||||
3643 | // Absolute value reduces number of sign bits by at most 1. | |||
3644 | return Tmp - 1; | |||
3645 | case Intrinsic::smin: | |||
3646 | case Intrinsic::smax: { | |||
3647 | const APInt *CLow, *CHigh; | |||
3648 | if (isSignedMinMaxIntrinsicClamp(II, CLow, CHigh)) | |||
3649 | return std::min(CLow->getNumSignBits(), CHigh->getNumSignBits()); | |||
3650 | } | |||
3651 | } | |||
3652 | } | |||
3653 | } | |||
3654 | } | |||
3655 | } | |||
3656 | ||||
3657 | // Finally, if we can prove that the top bits of the result are 0's or 1's, | |||
3658 | // use this information. | |||
3659 | ||||
3660 | // If we can examine all elements of a vector constant successfully, we're | |||
3661 | // done (we can't do any better than that). If not, keep trying. | |||
3662 | if (unsigned VecSignBits = | |||
3663 | computeNumSignBitsVectorConstant(V, DemandedElts, TyBits)) | |||
3664 | return VecSignBits; | |||
3665 | ||||
3666 | KnownBits Known(TyBits); | |||
3667 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
3668 | ||||
3669 | // If we know that the sign bit is either zero or one, determine the number of | |||
3670 | // identical bits in the top of the input value. | |||
3671 | return std::max(FirstAnswer, Known.countMinSignBits()); | |||
3672 | } | |||
3673 | ||||
3674 | Intrinsic::ID llvm::getIntrinsicForCallSite(const CallBase &CB, | |||
3675 | const TargetLibraryInfo *TLI) { | |||
3676 | const Function *F = CB.getCalledFunction(); | |||
3677 | if (!F) | |||
3678 | return Intrinsic::not_intrinsic; | |||
3679 | ||||
3680 | if (F->isIntrinsic()) | |||
3681 | return F->getIntrinsicID(); | |||
3682 | ||||
3683 | // We are going to infer semantics of a library function based on mapping it | |||
3684 | // to an LLVM intrinsic. Check that the library function is available from | |||
3685 | // this callbase and in this environment. | |||
3686 | LibFunc Func; | |||
3687 | if (F->hasLocalLinkage() || !TLI || !TLI->getLibFunc(CB, Func) || | |||
3688 | !CB.onlyReadsMemory()) | |||
3689 | return Intrinsic::not_intrinsic; | |||
3690 | ||||
3691 | switch (Func) { | |||
3692 | default: | |||
3693 | break; | |||
3694 | case LibFunc_sin: | |||
3695 | case LibFunc_sinf: | |||
3696 | case LibFunc_sinl: | |||
3697 | return Intrinsic::sin; | |||
3698 | case LibFunc_cos: | |||
3699 | case LibFunc_cosf: | |||
3700 | case LibFunc_cosl: | |||
3701 | return Intrinsic::cos; | |||
3702 | case LibFunc_exp: | |||
3703 | case LibFunc_expf: | |||
3704 | case LibFunc_expl: | |||
3705 | return Intrinsic::exp; | |||
3706 | case LibFunc_exp2: | |||
3707 | case LibFunc_exp2f: | |||
3708 | case LibFunc_exp2l: | |||
3709 | return Intrinsic::exp2; | |||
3710 | case LibFunc_log: | |||
3711 | case LibFunc_logf: | |||
3712 | case LibFunc_logl: | |||
3713 | return Intrinsic::log; | |||
3714 | case LibFunc_log10: | |||
3715 | case LibFunc_log10f: | |||
3716 | case LibFunc_log10l: | |||
3717 | return Intrinsic::log10; | |||
3718 | case LibFunc_log2: | |||
3719 | case LibFunc_log2f: | |||
3720 | case LibFunc_log2l: | |||
3721 | return Intrinsic::log2; | |||
3722 | case LibFunc_fabs: | |||
3723 | case LibFunc_fabsf: | |||
3724 | case LibFunc_fabsl: | |||
3725 | return Intrinsic::fabs; | |||
3726 | case LibFunc_fmin: | |||
3727 | case LibFunc_fminf: | |||
3728 | case LibFunc_fminl: | |||
3729 | return Intrinsic::minnum; | |||
3730 | case LibFunc_fmax: | |||
3731 | case LibFunc_fmaxf: | |||
3732 | case LibFunc_fmaxl: | |||
3733 | return Intrinsic::maxnum; | |||
3734 | case LibFunc_copysign: | |||
3735 | case LibFunc_copysignf: | |||
3736 | case LibFunc_copysignl: | |||
3737 | return Intrinsic::copysign; | |||
3738 | case LibFunc_floor: | |||
3739 | case LibFunc_floorf: | |||
3740 | case LibFunc_floorl: | |||
3741 | return Intrinsic::floor; | |||
3742 | case LibFunc_ceil: | |||
3743 | case LibFunc_ceilf: | |||
3744 | case LibFunc_ceill: | |||
3745 | return Intrinsic::ceil; | |||
3746 | case LibFunc_trunc: | |||
3747 | case LibFunc_truncf: | |||
3748 | case LibFunc_truncl: | |||
3749 | return Intrinsic::trunc; | |||
3750 | case LibFunc_rint: | |||
3751 | case LibFunc_rintf: | |||
3752 | case LibFunc_rintl: | |||
3753 | return Intrinsic::rint; | |||
3754 | case LibFunc_nearbyint: | |||
3755 | case LibFunc_nearbyintf: | |||
3756 | case LibFunc_nearbyintl: | |||
3757 | return Intrinsic::nearbyint; | |||
3758 | case LibFunc_round: | |||
3759 | case LibFunc_roundf: | |||
3760 | case LibFunc_roundl: | |||
3761 | return Intrinsic::round; | |||
3762 | case LibFunc_roundeven: | |||
3763 | case LibFunc_roundevenf: | |||
3764 | case LibFunc_roundevenl: | |||
3765 | return Intrinsic::roundeven; | |||
3766 | case LibFunc_pow: | |||
3767 | case LibFunc_powf: | |||
3768 | case LibFunc_powl: | |||
3769 | return Intrinsic::pow; | |||
3770 | case LibFunc_sqrt: | |||
3771 | case LibFunc_sqrtf: | |||
3772 | case LibFunc_sqrtl: | |||
3773 | return Intrinsic::sqrt; | |||
3774 | } | |||
3775 | ||||
3776 | return Intrinsic::not_intrinsic; | |||
3777 | } | |||
3778 | ||||
3779 | /// Return true if we can prove that the specified FP value is never equal to | |||
3780 | /// -0.0. | |||
3781 | /// NOTE: Do not check 'nsz' here because that fast-math-flag does not guarantee | |||
3782 | /// that a value is not -0.0. It only guarantees that -0.0 may be treated | |||
3783 | /// the same as +0.0 in floating-point ops. | |||
3784 | bool llvm::CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI, | |||
3785 | unsigned Depth) { | |||
3786 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
3787 | return !CFP->getValueAPF().isNegZero(); | |||
3788 | ||||
3789 | if (Depth == MaxAnalysisRecursionDepth) | |||
3790 | return false; | |||
3791 | ||||
3792 | auto *Op = dyn_cast<Operator>(V); | |||
3793 | if (!Op) | |||
3794 | return false; | |||
3795 | ||||
3796 | // (fadd x, 0.0) is guaranteed to return +0.0, not -0.0. | |||
3797 | if (match(Op, m_FAdd(m_Value(), m_PosZeroFP()))) | |||
3798 | return true; | |||
3799 | ||||
3800 | // sitofp and uitofp turn into +0.0 for zero. | |||
3801 | if (isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) | |||
3802 | return true; | |||
3803 | ||||
3804 | if (auto *Call = dyn_cast<CallInst>(Op)) { | |||
3805 | Intrinsic::ID IID = getIntrinsicForCallSite(*Call, TLI); | |||
3806 | switch (IID) { | |||
3807 | default: | |||
3808 | break; | |||
3809 | // sqrt(-0.0) = -0.0, no other negative results are possible. | |||
3810 | case Intrinsic::sqrt: | |||
3811 | case Intrinsic::canonicalize: | |||
3812 | return CannotBeNegativeZero(Call->getArgOperand(0), TLI, Depth + 1); | |||
3813 | case Intrinsic::experimental_constrained_sqrt: { | |||
3814 | // NOTE: This rounding mode restriction may be too strict. | |||
3815 | const auto *CI = cast<ConstrainedFPIntrinsic>(Call); | |||
3816 | if (CI->getRoundingMode() == RoundingMode::NearestTiesToEven) | |||
3817 | return CannotBeNegativeZero(Call->getArgOperand(0), TLI, Depth + 1); | |||
3818 | else | |||
3819 | return false; | |||
3820 | } | |||
3821 | // fabs(x) != -0.0 | |||
3822 | case Intrinsic::fabs: | |||
3823 | return true; | |||
3824 | // sitofp and uitofp turn into +0.0 for zero. | |||
3825 | case Intrinsic::experimental_constrained_sitofp: | |||
3826 | case Intrinsic::experimental_constrained_uitofp: | |||
3827 | return true; | |||
3828 | } | |||
3829 | } | |||
3830 | ||||
3831 | return false; | |||
3832 | } | |||
3833 | ||||
3834 | /// If \p SignBitOnly is true, test for a known 0 sign bit rather than a | |||
3835 | /// standard ordered compare. e.g. make -0.0 olt 0.0 be true because of the sign | |||
3836 | /// bit despite comparing equal. | |||
3837 | static bool cannotBeOrderedLessThanZeroImpl(const Value *V, | |||
3838 | const TargetLibraryInfo *TLI, | |||
3839 | bool SignBitOnly, | |||
3840 | unsigned Depth) { | |||
3841 | // TODO: This function does not do the right thing when SignBitOnly is true | |||
3842 | // and we're lowering to a hypothetical IEEE 754-compliant-but-evil platform | |||
3843 | // which flips the sign bits of NaNs. See | |||
3844 | // https://llvm.org/bugs/show_bug.cgi?id=31702. | |||
3845 | ||||
3846 | if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { | |||
3847 | return !CFP->getValueAPF().isNegative() || | |||
3848 | (!SignBitOnly && CFP->getValueAPF().isZero()); | |||
3849 | } | |||
3850 | ||||
3851 | // Handle vector of constants. | |||
3852 | if (auto *CV = dyn_cast<Constant>(V)) { | |||
3853 | if (auto *CVFVTy = dyn_cast<FixedVectorType>(CV->getType())) { | |||
3854 | unsigned NumElts = CVFVTy->getNumElements(); | |||
3855 | for (unsigned i = 0; i != NumElts; ++i) { | |||
3856 | auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i)); | |||
3857 | if (!CFP) | |||
3858 | return false; | |||
3859 | if (CFP->getValueAPF().isNegative() && | |||
3860 | (SignBitOnly || !CFP->getValueAPF().isZero())) | |||
3861 | return false; | |||
3862 | } | |||
3863 | ||||
3864 | // All non-negative ConstantFPs. | |||
3865 | return true; | |||
3866 | } | |||
3867 | } | |||
3868 | ||||
3869 | if (Depth == MaxAnalysisRecursionDepth) | |||
3870 | return false; | |||
3871 | ||||
3872 | const Operator *I = dyn_cast<Operator>(V); | |||
3873 | if (!I) | |||
3874 | return false; | |||
3875 | ||||
3876 | switch (I->getOpcode()) { | |||
3877 | default: | |||
3878 | break; | |||
3879 | // Unsigned integers are always nonnegative. | |||
3880 | case Instruction::UIToFP: | |||
3881 | return true; | |||
3882 | case Instruction::FDiv: | |||
3883 | // X / X is always exactly 1.0 or a NaN. | |||
3884 | if (I->getOperand(0) == I->getOperand(1) && | |||
3885 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs())) | |||
3886 | return true; | |||
3887 | ||||
3888 | // Set SignBitOnly for RHS, because X / -0.0 is -Inf (or NaN). | |||
3889 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3890 | Depth + 1) && | |||
3891 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, | |||
3892 | /*SignBitOnly*/ true, Depth + 1); | |||
3893 | case Instruction::FMul: | |||
3894 | // X * X is always non-negative or a NaN. | |||
3895 | if (I->getOperand(0) == I->getOperand(1) && | |||
3896 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs())) | |||
3897 | return true; | |||
3898 | ||||
3899 | [[fallthrough]]; | |||
3900 | case Instruction::FAdd: | |||
3901 | case Instruction::FRem: | |||
3902 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3903 | Depth + 1) && | |||
3904 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3905 | Depth + 1); | |||
3906 | case Instruction::Select: | |||
3907 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3908 | Depth + 1) && | |||
3909 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, | |||
3910 | Depth + 1); | |||
3911 | case Instruction::FPExt: | |||
3912 | case Instruction::FPTrunc: | |||
3913 | // Widening/narrowing never change sign. | |||
3914 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3915 | Depth + 1); | |||
3916 | case Instruction::ExtractElement: | |||
3917 | // Look through extract element. At the moment we keep this simple and skip | |||
3918 | // tracking the specific element. But at least we might find information | |||
3919 | // valid for all elements of the vector. | |||
3920 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3921 | Depth + 1); | |||
3922 | case Instruction::Call: | |||
3923 | const auto *CI = cast<CallInst>(I); | |||
3924 | Intrinsic::ID IID = getIntrinsicForCallSite(*CI, TLI); | |||
3925 | switch (IID) { | |||
3926 | default: | |||
3927 | break; | |||
3928 | case Intrinsic::canonicalize: | |||
3929 | case Intrinsic::arithmetic_fence: | |||
3930 | case Intrinsic::floor: | |||
3931 | case Intrinsic::ceil: | |||
3932 | case Intrinsic::trunc: | |||
3933 | case Intrinsic::rint: | |||
3934 | case Intrinsic::nearbyint: | |||
3935 | case Intrinsic::round: | |||
3936 | case Intrinsic::roundeven: | |||
3937 | case Intrinsic::fptrunc_round: | |||
3938 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, Depth + 1); | |||
3939 | case Intrinsic::maxnum: { | |||
3940 | Value *V0 = I->getOperand(0), *V1 = I->getOperand(1); | |||
3941 | auto isPositiveNum = [&](Value *V) { | |||
3942 | if (SignBitOnly) { | |||
3943 | // With SignBitOnly, this is tricky because the result of | |||
3944 | // maxnum(+0.0, -0.0) is unspecified. Just check if the operand is | |||
3945 | // a constant strictly greater than 0.0. | |||
3946 | const APFloat *C; | |||
3947 | return match(V, m_APFloat(C)) && | |||
3948 | *C > APFloat::getZero(C->getSemantics()); | |||
3949 | } | |||
3950 | ||||
3951 | // -0.0 compares equal to 0.0, so if this operand is at least -0.0, | |||
3952 | // maxnum can't be ordered-less-than-zero. | |||
3953 | return isKnownNeverNaN(V, TLI) && | |||
3954 | cannotBeOrderedLessThanZeroImpl(V, TLI, false, Depth + 1); | |||
3955 | }; | |||
3956 | ||||
3957 | // TODO: This could be improved. We could also check that neither operand | |||
3958 | // has its sign bit set (and at least 1 is not-NAN?). | |||
3959 | return isPositiveNum(V0) || isPositiveNum(V1); | |||
3960 | } | |||
3961 | ||||
3962 | case Intrinsic::maximum: | |||
3963 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3964 | Depth + 1) || | |||
3965 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3966 | Depth + 1); | |||
3967 | case Intrinsic::minnum: | |||
3968 | case Intrinsic::minimum: | |||
3969 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3970 | Depth + 1) && | |||
3971 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3972 | Depth + 1); | |||
3973 | case Intrinsic::exp: | |||
3974 | case Intrinsic::exp2: | |||
3975 | case Intrinsic::fabs: | |||
3976 | return true; | |||
3977 | case Intrinsic::copysign: | |||
3978 | // Only the sign operand matters. | |||
3979 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, true, | |||
3980 | Depth + 1); | |||
3981 | case Intrinsic::sqrt: | |||
3982 | // sqrt(x) is always >= -0 or NaN. Moreover, sqrt(x) == -0 iff x == -0. | |||
3983 | if (!SignBitOnly) | |||
3984 | return true; | |||
3985 | return CI->hasNoNaNs() && (CI->hasNoSignedZeros() || | |||
3986 | CannotBeNegativeZero(CI->getOperand(0), TLI)); | |||
3987 | ||||
3988 | case Intrinsic::powi: | |||
3989 | if (ConstantInt *Exponent = dyn_cast<ConstantInt>(I->getOperand(1))) { | |||
3990 | // powi(x,n) is non-negative if n is even. | |||
3991 | if (Exponent->getBitWidth() <= 64 && Exponent->getSExtValue() % 2u == 0) | |||
3992 | return true; | |||
3993 | } | |||
3994 | // TODO: This is not correct. Given that exp is an integer, here are the | |||
3995 | // ways that pow can return a negative value: | |||
3996 | // | |||
3997 | // pow(x, exp) --> negative if exp is odd and x is negative. | |||
3998 | // pow(-0, exp) --> -inf if exp is negative odd. | |||
3999 | // pow(-0, exp) --> -0 if exp is positive odd. | |||
4000 | // pow(-inf, exp) --> -0 if exp is negative odd. | |||
4001 | // pow(-inf, exp) --> -inf if exp is positive odd. | |||
4002 | // | |||
4003 | // Therefore, if !SignBitOnly, we can return true if x >= +0 or x is NaN, | |||
4004 | // but we must return false if x == -0. Unfortunately we do not currently | |||
4005 | // have a way of expressing this constraint. See details in | |||
4006 | // https://llvm.org/bugs/show_bug.cgi?id=31702. | |||
4007 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
4008 | Depth + 1); | |||
4009 | ||||
4010 | case Intrinsic::fma: | |||
4011 | case Intrinsic::fmuladd: | |||
4012 | // x*x+y is non-negative if y is non-negative. | |||
4013 | return I->getOperand(0) == I->getOperand(1) && | |||
4014 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()) && | |||
4015 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, | |||
4016 | Depth + 1); | |||
4017 | } | |||
4018 | break; | |||
4019 | } | |||
4020 | return false; | |||
4021 | } | |||
4022 | ||||
4023 | bool llvm::CannotBeOrderedLessThanZero(const Value *V, | |||
4024 | const TargetLibraryInfo *TLI) { | |||
4025 | return cannotBeOrderedLessThanZeroImpl(V, TLI, false, 0); | |||
4026 | } | |||
4027 | ||||
4028 | bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) { | |||
4029 | return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0); | |||
4030 | } | |||
4031 | ||||
4032 | bool llvm::isKnownNeverInfinity(const Value *V, const TargetLibraryInfo *TLI, | |||
4033 | unsigned Depth) { | |||
4034 | assert(V->getType()->isFPOrFPVectorTy() && "Querying for Inf on non-FP type")(static_cast <bool> (V->getType()->isFPOrFPVectorTy () && "Querying for Inf on non-FP type") ? void (0) : __assert_fail ("V->getType()->isFPOrFPVectorTy() && \"Querying for Inf on non-FP type\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4034, __extension__ __PRETTY_FUNCTION__ )); | |||
4035 | ||||
4036 | // If we're told that infinities won't happen, assume they won't. | |||
4037 | if (auto *FPMathOp = dyn_cast<FPMathOperator>(V)) | |||
4038 | if (FPMathOp->hasNoInfs()) | |||
4039 | return true; | |||
4040 | ||||
4041 | if (const auto *Arg = dyn_cast<Argument>(V)) { | |||
4042 | if ((Arg->getNoFPClass() & fcInf) == fcInf) | |||
4043 | return true; | |||
4044 | } | |||
4045 | ||||
4046 | // TODO: Use fpclass like API for isKnown queries and distinguish +inf from | |||
4047 | // -inf. | |||
4048 | if (const auto *CB = dyn_cast<CallBase>(V)) { | |||
4049 | if ((CB->getRetNoFPClass() & fcInf) == fcInf) | |||
4050 | return true; | |||
4051 | } | |||
4052 | ||||
4053 | // Handle scalar constants. | |||
4054 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
4055 | return !CFP->isInfinity(); | |||
4056 | ||||
4057 | if (Depth == MaxAnalysisRecursionDepth) | |||
4058 | return false; | |||
4059 | ||||
4060 | if (auto *Inst = dyn_cast<Instruction>(V)) { | |||
4061 | switch (Inst->getOpcode()) { | |||
4062 | case Instruction::Select: { | |||
4063 | return isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1) && | |||
4064 | isKnownNeverInfinity(Inst->getOperand(2), TLI, Depth + 1); | |||
4065 | } | |||
4066 | case Instruction::SIToFP: | |||
4067 | case Instruction::UIToFP: { | |||
4068 | // Get width of largest magnitude integer (remove a bit if signed). | |||
4069 | // This still works for a signed minimum value because the largest FP | |||
4070 | // value is scaled by some fraction close to 2.0 (1.0 + 0.xxxx). | |||
4071 | int IntSize = Inst->getOperand(0)->getType()->getScalarSizeInBits(); | |||
4072 | if (Inst->getOpcode() == Instruction::SIToFP) | |||
4073 | --IntSize; | |||
4074 | ||||
4075 | // If the exponent of the largest finite FP value can hold the largest | |||
4076 | // integer, the result of the cast must be finite. | |||
4077 | Type *FPTy = Inst->getType()->getScalarType(); | |||
4078 | return ilogb(APFloat::getLargest(FPTy->getFltSemantics())) >= IntSize; | |||
4079 | } | |||
4080 | case Instruction::FNeg: | |||
4081 | case Instruction::FPExt: { | |||
4082 | // Peek through to source op. If it is not infinity, this is not infinity. | |||
4083 | return isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1); | |||
4084 | } | |||
4085 | case Instruction::FPTrunc: { | |||
4086 | // Need a range check. | |||
4087 | return false; | |||
4088 | } | |||
4089 | default: | |||
4090 | break; | |||
4091 | } | |||
4092 | ||||
4093 | if (const auto *II = dyn_cast<IntrinsicInst>(V)) { | |||
4094 | switch (II->getIntrinsicID()) { | |||
4095 | case Intrinsic::sin: | |||
4096 | case Intrinsic::cos: | |||
4097 | // Return NaN on infinite inputs. | |||
4098 | return true; | |||
4099 | case Intrinsic::fabs: | |||
4100 | case Intrinsic::sqrt: | |||
4101 | case Intrinsic::canonicalize: | |||
4102 | case Intrinsic::copysign: | |||
4103 | case Intrinsic::arithmetic_fence: | |||
4104 | case Intrinsic::trunc: | |||
4105 | return isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1); | |||
4106 | case Intrinsic::floor: | |||
4107 | case Intrinsic::ceil: | |||
4108 | case Intrinsic::rint: | |||
4109 | case Intrinsic::nearbyint: | |||
4110 | case Intrinsic::round: | |||
4111 | case Intrinsic::roundeven: | |||
4112 | // PPC_FP128 is a special case. | |||
4113 | if (V->getType()->isMultiUnitFPType()) | |||
4114 | return false; | |||
4115 | return isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1); | |||
4116 | case Intrinsic::fptrunc_round: | |||
4117 | // Requires knowing the value range. | |||
4118 | return false; | |||
4119 | case Intrinsic::minnum: | |||
4120 | case Intrinsic::maxnum: | |||
4121 | case Intrinsic::minimum: | |||
4122 | case Intrinsic::maximum: | |||
4123 | return isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) && | |||
4124 | isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1); | |||
4125 | case Intrinsic::log: | |||
4126 | case Intrinsic::log10: | |||
4127 | case Intrinsic::log2: | |||
4128 | // log(+inf) -> +inf | |||
4129 | // log([+-]0.0) -> -inf | |||
4130 | // log(-inf) -> nan | |||
4131 | // log(-x) -> nan | |||
4132 | // TODO: We lack API to check the == 0 case. | |||
4133 | return false; | |||
4134 | case Intrinsic::exp: | |||
4135 | case Intrinsic::exp2: | |||
4136 | case Intrinsic::pow: | |||
4137 | case Intrinsic::powi: | |||
4138 | case Intrinsic::fma: | |||
4139 | case Intrinsic::fmuladd: | |||
4140 | // These can return infinities on overflow cases, so it's hard to prove | |||
4141 | // anything about it. | |||
4142 | return false; | |||
4143 | default: | |||
4144 | break; | |||
4145 | } | |||
4146 | } | |||
4147 | } | |||
4148 | ||||
4149 | // try to handle fixed width vector constants | |||
4150 | auto *VFVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
4151 | if (VFVTy && isa<Constant>(V)) { | |||
4152 | // For vectors, verify that each element is not infinity. | |||
4153 | unsigned NumElts = VFVTy->getNumElements(); | |||
4154 | for (unsigned i = 0; i != NumElts; ++i) { | |||
4155 | Constant *Elt = cast<Constant>(V)->getAggregateElement(i); | |||
4156 | if (!Elt) | |||
4157 | return false; | |||
4158 | if (isa<UndefValue>(Elt)) | |||
4159 | continue; | |||
4160 | auto *CElt = dyn_cast<ConstantFP>(Elt); | |||
4161 | if (!CElt || CElt->isInfinity()) | |||
4162 | return false; | |||
4163 | } | |||
4164 | // All elements were confirmed non-infinity or undefined. | |||
4165 | return true; | |||
4166 | } | |||
4167 | ||||
4168 | // was not able to prove that V never contains infinity | |||
4169 | return false; | |||
4170 | } | |||
4171 | ||||
4172 | bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI, | |||
4173 | unsigned Depth) { | |||
4174 | assert(V->getType()->isFPOrFPVectorTy() && "Querying for NaN on non-FP type")(static_cast <bool> (V->getType()->isFPOrFPVectorTy () && "Querying for NaN on non-FP type") ? void (0) : __assert_fail ("V->getType()->isFPOrFPVectorTy() && \"Querying for NaN on non-FP type\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4174, __extension__ __PRETTY_FUNCTION__ )); | |||
4175 | ||||
4176 | // If we're told that NaNs won't happen, assume they won't. | |||
4177 | if (auto *FPMathOp = dyn_cast<FPMathOperator>(V)) | |||
4178 | if (FPMathOp->hasNoNaNs()) | |||
4179 | return true; | |||
4180 | ||||
4181 | if (const auto *Arg = dyn_cast<Argument>(V)) { | |||
4182 | if ((Arg->getNoFPClass() & fcNan) == fcNan) | |||
4183 | return true; | |||
4184 | } | |||
4185 | ||||
4186 | // TODO: Use fpclass like API for isKnown queries and distinguish snan from | |||
4187 | // qnan. | |||
4188 | if (const auto *CB = dyn_cast<CallBase>(V)) { | |||
4189 | FPClassTest Mask = CB->getRetNoFPClass(); | |||
4190 | if ((Mask & fcNan) == fcNan) | |||
4191 | return true; | |||
4192 | } | |||
4193 | ||||
4194 | // Handle scalar constants. | |||
4195 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
4196 | return !CFP->isNaN(); | |||
4197 | ||||
4198 | if (Depth == MaxAnalysisRecursionDepth) | |||
4199 | return false; | |||
4200 | ||||
4201 | if (auto *Inst = dyn_cast<Instruction>(V)) { | |||
4202 | switch (Inst->getOpcode()) { | |||
4203 | case Instruction::FAdd: | |||
4204 | case Instruction::FSub: | |||
4205 | // Adding positive and negative infinity produces NaN. | |||
4206 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) && | |||
4207 | isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && | |||
4208 | (isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) || | |||
4209 | isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1)); | |||
4210 | ||||
4211 | case Instruction::FMul: | |||
4212 | // Zero multiplied with infinity produces NaN. | |||
4213 | // FIXME: If neither side can be zero fmul never produces NaN. | |||
4214 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) && | |||
4215 | isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) && | |||
4216 | isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && | |||
4217 | isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1); | |||
4218 | ||||
4219 | case Instruction::FDiv: | |||
4220 | case Instruction::FRem: | |||
4221 | // FIXME: Only 0/0, Inf/Inf, Inf REM x and x REM 0 produce NaN. | |||
4222 | return false; | |||
4223 | ||||
4224 | case Instruction::Select: { | |||
4225 | return isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && | |||
4226 | isKnownNeverNaN(Inst->getOperand(2), TLI, Depth + 1); | |||
4227 | } | |||
4228 | case Instruction::SIToFP: | |||
4229 | case Instruction::UIToFP: | |||
4230 | return true; | |||
4231 | case Instruction::FPTrunc: | |||
4232 | case Instruction::FPExt: | |||
4233 | case Instruction::FNeg: | |||
4234 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1); | |||
4235 | default: | |||
4236 | break; | |||
4237 | } | |||
4238 | } | |||
4239 | ||||
4240 | if (const auto *II = dyn_cast<IntrinsicInst>(V)) { | |||
4241 | switch (II->getIntrinsicID()) { | |||
4242 | case Intrinsic::canonicalize: | |||
4243 | case Intrinsic::fabs: | |||
4244 | case Intrinsic::copysign: | |||
4245 | case Intrinsic::exp: | |||
4246 | case Intrinsic::exp2: | |||
4247 | case Intrinsic::floor: | |||
4248 | case Intrinsic::ceil: | |||
4249 | case Intrinsic::trunc: | |||
4250 | case Intrinsic::rint: | |||
4251 | case Intrinsic::nearbyint: | |||
4252 | case Intrinsic::round: | |||
4253 | case Intrinsic::roundeven: | |||
4254 | case Intrinsic::arithmetic_fence: | |||
4255 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1); | |||
4256 | case Intrinsic::sqrt: | |||
4257 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) && | |||
4258 | CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI); | |||
4259 | case Intrinsic::minnum: | |||
4260 | case Intrinsic::maxnum: | |||
4261 | // If either operand is not NaN, the result is not NaN. | |||
4262 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) || | |||
4263 | isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1); | |||
4264 | default: | |||
4265 | return false; | |||
4266 | } | |||
4267 | } | |||
4268 | ||||
4269 | // Try to handle fixed width vector constants | |||
4270 | auto *VFVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
4271 | if (VFVTy && isa<Constant>(V)) { | |||
4272 | // For vectors, verify that each element is not NaN. | |||
4273 | unsigned NumElts = VFVTy->getNumElements(); | |||
4274 | for (unsigned i = 0; i != NumElts; ++i) { | |||
4275 | Constant *Elt = cast<Constant>(V)->getAggregateElement(i); | |||
4276 | if (!Elt) | |||
4277 | return false; | |||
4278 | if (isa<UndefValue>(Elt)) | |||
4279 | continue; | |||
4280 | auto *CElt = dyn_cast<ConstantFP>(Elt); | |||
4281 | if (!CElt || CElt->isNaN()) | |||
4282 | return false; | |||
4283 | } | |||
4284 | // All elements were confirmed not-NaN or undefined. | |||
4285 | return true; | |||
4286 | } | |||
4287 | ||||
4288 | // Was not able to prove that V never contains NaN | |||
4289 | return false; | |||
4290 | } | |||
4291 | ||||
4292 | /// Return true if it's possible to assume IEEE treatment of input denormals in | |||
4293 | /// \p F for \p Val. | |||
4294 | static bool inputDenormalIsIEEE(const Function &F, const Type *Ty) { | |||
4295 | Ty = Ty->getScalarType(); | |||
4296 | return F.getDenormalMode(Ty->getFltSemantics()).Input == DenormalMode::IEEE; | |||
4297 | } | |||
4298 | ||||
4299 | bool KnownFPClass::isKnownNeverLogicalZero(const Function &F, Type *Ty) const { | |||
4300 | return isKnownNeverZero() && | |||
4301 | (isKnownNeverSubnormal() || inputDenormalIsIEEE(F, Ty)); | |||
4302 | } | |||
4303 | ||||
4304 | /// Returns a pair of values, which if passed to llvm.is.fpclass, returns the | |||
4305 | /// same result as an fcmp with the given operands. | |||
4306 | std::pair<Value *, FPClassTest> llvm::fcmpToClassTest(FCmpInst::Predicate Pred, | |||
4307 | const Function &F, | |||
4308 | Value *LHS, Value *RHS, | |||
4309 | bool LookThroughSrc) { | |||
4310 | const APFloat *ConstRHS; | |||
4311 | if (!match(RHS, m_APFloat(ConstRHS))) | |||
4312 | return {nullptr, fcNone}; | |||
4313 | ||||
4314 | if (ConstRHS->isZero()) { | |||
4315 | // Compares with fcNone are only exactly equal to fcZero if input denormals | |||
4316 | // are not flushed. | |||
4317 | // TODO: Handle DAZ by expanding masks to cover subnormal cases. | |||
4318 | if (Pred != FCmpInst::FCMP_ORD && Pred != FCmpInst::FCMP_UNO && | |||
4319 | !inputDenormalIsIEEE(F, LHS->getType())) | |||
4320 | return {nullptr, fcNone}; | |||
4321 | ||||
4322 | switch (Pred) { | |||
4323 | case FCmpInst::FCMP_OEQ: // Match x == 0.0 | |||
4324 | return {LHS, fcZero}; | |||
4325 | case FCmpInst::FCMP_UEQ: // Match isnan(x) || (x == 0.0) | |||
4326 | return {LHS, fcZero | fcNan}; | |||
4327 | case FCmpInst::FCMP_UNE: // Match (x != 0.0) | |||
4328 | return {LHS, ~fcZero}; | |||
4329 | case FCmpInst::FCMP_ONE: // Match !isnan(x) && x != 0.0 | |||
4330 | return {LHS, ~fcNan & ~fcZero}; | |||
4331 | case FCmpInst::FCMP_ORD: | |||
4332 | // Canonical form of ord/uno is with a zero. We could also handle | |||
4333 | // non-canonical other non-NaN constants or LHS == RHS. | |||
4334 | return {LHS, ~fcNan}; | |||
4335 | case FCmpInst::FCMP_UNO: | |||
4336 | return {LHS, fcNan}; | |||
4337 | case FCmpInst::FCMP_OGT: // x > 0 | |||
4338 | return {LHS, fcPosSubnormal | fcPosNormal | fcPosInf}; | |||
4339 | case FCmpInst::FCMP_UGT: // isnan(x) || x > 0 | |||
4340 | return {LHS, fcPosSubnormal | fcPosNormal | fcPosInf | fcNan}; | |||
4341 | case FCmpInst::FCMP_OGE: // x >= 0 | |||
4342 | return {LHS, fcPositive | fcNegZero}; | |||
4343 | case FCmpInst::FCMP_UGE: // isnan(x) || x >= 0 | |||
4344 | return {LHS, fcPositive | fcNegZero | fcNan}; | |||
4345 | case FCmpInst::FCMP_OLT: // x < 0 | |||
4346 | return {LHS, fcNegSubnormal | fcNegNormal | fcNegInf}; | |||
4347 | case FCmpInst::FCMP_ULT: // isnan(x) || x < 0 | |||
4348 | return {LHS, fcNegSubnormal | fcNegNormal | fcNegInf | fcNan}; | |||
4349 | case FCmpInst::FCMP_OLE: // x <= 0 | |||
4350 | return {LHS, fcNegative | fcPosZero}; | |||
4351 | case FCmpInst::FCMP_ULE: // isnan(x) || x <= 0 | |||
4352 | return {LHS, fcNegative | fcPosZero | fcNan}; | |||
4353 | default: | |||
4354 | break; | |||
4355 | } | |||
4356 | ||||
4357 | return {nullptr, fcNone}; | |||
4358 | } | |||
4359 | ||||
4360 | Value *Src = LHS; | |||
4361 | const bool IsFabs = LookThroughSrc && match(LHS, m_FAbs(m_Value(Src))); | |||
4362 | ||||
4363 | // Compute the test mask that would return true for the ordered comparisons. | |||
4364 | FPClassTest Mask; | |||
4365 | ||||
4366 | if (ConstRHS->isInfinity()) { | |||
4367 | switch (Pred) { | |||
4368 | case FCmpInst::FCMP_OEQ: | |||
4369 | case FCmpInst::FCMP_UNE: { | |||
4370 | // Match __builtin_isinf patterns | |||
4371 | // | |||
4372 | // fcmp oeq x, +inf -> is_fpclass x, fcPosInf | |||
4373 | // fcmp oeq fabs(x), +inf -> is_fpclass x, fcInf | |||
4374 | // fcmp oeq x, -inf -> is_fpclass x, fcNegInf | |||
4375 | // fcmp oeq fabs(x), -inf -> is_fpclass x, 0 -> false | |||
4376 | // | |||
4377 | // fcmp une x, +inf -> is_fpclass x, ~fcPosInf | |||
4378 | // fcmp une fabs(x), +inf -> is_fpclass x, ~fcInf | |||
4379 | // fcmp une x, -inf -> is_fpclass x, ~fcNegInf | |||
4380 | // fcmp une fabs(x), -inf -> is_fpclass x, fcAllFlags -> true | |||
4381 | ||||
4382 | if (ConstRHS->isNegative()) { | |||
4383 | Mask = fcNegInf; | |||
4384 | if (IsFabs) | |||
4385 | Mask = fcNone; | |||
4386 | } else { | |||
4387 | Mask = fcPosInf; | |||
4388 | if (IsFabs) | |||
4389 | Mask |= fcNegInf; | |||
4390 | } | |||
4391 | ||||
4392 | break; | |||
4393 | } | |||
4394 | case FCmpInst::FCMP_ONE: | |||
4395 | case FCmpInst::FCMP_UEQ: { | |||
4396 | // Match __builtin_isinf patterns | |||
4397 | // fcmp one x, -inf -> is_fpclass x, fcNegInf | |||
4398 | // fcmp one fabs(x), -inf -> is_fpclass x, ~fcNegInf & ~fcNan | |||
4399 | // fcmp one x, +inf -> is_fpclass x, ~fcNegInf & ~fcNan | |||
4400 | // fcmp one fabs(x), +inf -> is_fpclass x, ~fcInf & fcNan | |||
4401 | // | |||
4402 | // fcmp ueq x, +inf -> is_fpclass x, fcPosInf|fcNan | |||
4403 | // fcmp ueq (fabs x), +inf -> is_fpclass x, fcInf|fcNan | |||
4404 | // fcmp ueq x, -inf -> is_fpclass x, fcNegInf|fcNan | |||
4405 | // fcmp ueq fabs(x), -inf -> is_fpclass x, fcNan | |||
4406 | if (ConstRHS->isNegative()) { | |||
4407 | Mask = ~fcNegInf & ~fcNan; | |||
4408 | if (IsFabs) | |||
4409 | Mask = ~fcNan; | |||
4410 | } else { | |||
4411 | Mask = ~fcPosInf & ~fcNan; | |||
4412 | if (IsFabs) | |||
4413 | Mask &= ~fcNegInf; | |||
4414 | } | |||
4415 | ||||
4416 | break; | |||
4417 | } | |||
4418 | case FCmpInst::FCMP_OLT: | |||
4419 | case FCmpInst::FCMP_UGE: { | |||
4420 | if (ConstRHS->isNegative()) // TODO | |||
4421 | return {nullptr, fcNone}; | |||
4422 | ||||
4423 | // fcmp olt fabs(x), +inf -> fcFinite | |||
4424 | // fcmp uge fabs(x), +inf -> ~fcFinite | |||
4425 | // fcmp olt x, +inf -> fcFinite|fcNegInf | |||
4426 | // fcmp uge x, +inf -> ~(fcFinite|fcNegInf) | |||
4427 | Mask = fcFinite; | |||
4428 | if (!IsFabs) | |||
4429 | Mask |= fcNegInf; | |||
4430 | break; | |||
4431 | } | |||
4432 | case FCmpInst::FCMP_OGE: | |||
4433 | case FCmpInst::FCMP_ULT: { | |||
4434 | if (ConstRHS->isNegative()) // TODO | |||
4435 | return {nullptr, fcNone}; | |||
4436 | ||||
4437 | // fcmp oge fabs(x), +inf -> fcInf | |||
4438 | // fcmp oge x, +inf -> fcPosInf | |||
4439 | // fcmp ult fabs(x), +inf -> ~fcInf | |||
4440 | // fcmp ult x, +inf -> ~fcPosInf | |||
4441 | Mask = fcPosInf; | |||
4442 | if (IsFabs) | |||
4443 | Mask |= fcNegInf; | |||
4444 | break; | |||
4445 | } | |||
4446 | default: | |||
4447 | return {nullptr, fcNone}; | |||
4448 | } | |||
4449 | } else if (ConstRHS->isSmallestNormalized() && !ConstRHS->isNegative()) { | |||
4450 | // Match pattern that's used in __builtin_isnormal. | |||
4451 | switch (Pred) { | |||
4452 | case FCmpInst::FCMP_OLT: | |||
4453 | case FCmpInst::FCMP_UGE: { | |||
4454 | // fcmp olt x, smallest_normal -> fcNegInf|fcNegNormal|fcSubnormal|fcZero | |||
4455 | // fcmp olt fabs(x), smallest_normal -> fcSubnormal|fcZero | |||
4456 | // fcmp uge x, smallest_normal -> fcNan|fcPosNormal|fcPosInf | |||
4457 | // fcmp uge fabs(x), smallest_normal -> ~(fcSubnormal|fcZero) | |||
4458 | Mask = fcZero | fcSubnormal; | |||
4459 | if (!IsFabs) | |||
4460 | Mask |= fcNegNormal | fcNegInf; | |||
4461 | ||||
4462 | break; | |||
4463 | } | |||
4464 | case FCmpInst::FCMP_OGE: | |||
4465 | case FCmpInst::FCMP_ULT: { | |||
4466 | // fcmp oge x, smallest_normal -> fcPosNormal | fcPosInf | |||
4467 | // fcmp oge fabs(x), smallest_normal -> fcInf | fcNormal | |||
4468 | // fcmp ult x, smallest_normal -> ~(fcPosNormal | fcPosInf) | |||
4469 | // fcmp ult fabs(x), smallest_normal -> ~(fcInf | fcNormal) | |||
4470 | Mask = fcPosInf | fcPosNormal; | |||
4471 | if (IsFabs) | |||
4472 | Mask |= fcNegInf | fcNegNormal; | |||
4473 | break; | |||
4474 | } | |||
4475 | default: | |||
4476 | return {nullptr, fcNone}; | |||
4477 | } | |||
4478 | } else | |||
4479 | return {nullptr, fcNone}; | |||
4480 | ||||
4481 | // Invert the comparison for the unordered cases. | |||
4482 | if (FCmpInst::isUnordered(Pred)) | |||
4483 | Mask = ~Mask; | |||
4484 | ||||
4485 | return {Src, Mask}; | |||
4486 | } | |||
4487 | ||||
4488 | static FPClassTest computeKnownFPClassFromAssumes(const Value *V, | |||
4489 | const Query &Q) { | |||
4490 | FPClassTest KnownFromAssume = fcAllFlags; | |||
4491 | ||||
4492 | // Try to restrict the floating-point classes based on information from | |||
4493 | // assumptions. | |||
4494 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { | |||
4495 | if (!AssumeVH) | |||
4496 | continue; | |||
4497 | CallInst *I = cast<CallInst>(AssumeVH); | |||
4498 | const Function *F = I->getFunction(); | |||
4499 | ||||
4500 | assert(F == Q.CxtI->getParent()->getParent() &&(static_cast <bool> (F == Q.CxtI->getParent()->getParent () && "Got assumption for the wrong function!") ? void (0) : __assert_fail ("F == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4501, __extension__ __PRETTY_FUNCTION__ )) | |||
4501 | "Got assumption for the wrong function!")(static_cast <bool> (F == Q.CxtI->getParent()->getParent () && "Got assumption for the wrong function!") ? void (0) : __assert_fail ("F == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4501, __extension__ __PRETTY_FUNCTION__ )); | |||
4502 | assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4503, __extension__ __PRETTY_FUNCTION__ )) | |||
4503 | "must be an assume intrinsic")(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4503, __extension__ __PRETTY_FUNCTION__ )); | |||
4504 | ||||
4505 | if (!isValidAssumeForContext(I, Q.CxtI, Q.DT)) | |||
4506 | continue; | |||
4507 | ||||
4508 | CmpInst::Predicate Pred; | |||
4509 | Value *LHS, *RHS; | |||
4510 | uint64_t ClassVal = 0; | |||
4511 | if (match(I->getArgOperand(0), m_FCmp(Pred, m_Value(LHS), m_Value(RHS)))) { | |||
4512 | auto [TestedValue, TestedMask] = | |||
4513 | fcmpToClassTest(Pred, *F, LHS, RHS, true); | |||
4514 | // First see if we can fold in fabs/fneg into the test. | |||
4515 | if (TestedValue == V) | |||
4516 | KnownFromAssume &= TestedMask; | |||
4517 | else { | |||
4518 | // Try again without the lookthrough if we found a different source | |||
4519 | // value. | |||
4520 | auto [TestedValue, TestedMask] = | |||
4521 | fcmpToClassTest(Pred, *F, LHS, RHS, false); | |||
4522 | if (TestedValue == V) | |||
4523 | KnownFromAssume &= TestedMask; | |||
4524 | } | |||
4525 | } else if (match(I->getArgOperand(0), | |||
4526 | m_Intrinsic<Intrinsic::is_fpclass>( | |||
4527 | m_Value(LHS), m_ConstantInt(ClassVal)))) { | |||
4528 | KnownFromAssume &= static_cast<FPClassTest>(ClassVal); | |||
4529 | } | |||
4530 | } | |||
4531 | ||||
4532 | return KnownFromAssume; | |||
4533 | } | |||
4534 | ||||
4535 | void computeKnownFPClass(const Value *V, const APInt &DemandedElts, | |||
4536 | FPClassTest InterestedClasses, KnownFPClass &Known, | |||
4537 | unsigned Depth, const Query &Q, | |||
4538 | const TargetLibraryInfo *TLI); | |||
4539 | ||||
4540 | static void computeKnownFPClass(const Value *V, KnownFPClass &Known, | |||
4541 | FPClassTest InterestedClasses, unsigned Depth, | |||
4542 | const Query &Q, const TargetLibraryInfo *TLI) { | |||
4543 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
4544 | APInt DemandedElts = | |||
4545 | FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1); | |||
4546 | computeKnownFPClass(V, DemandedElts, InterestedClasses, Known, Depth, Q, TLI); | |||
4547 | } | |||
4548 | ||||
4549 | static void computeKnownFPClassForFPTrunc(const Operator *Op, | |||
4550 | const APInt &DemandedElts, | |||
4551 | FPClassTest InterestedClasses, | |||
4552 | KnownFPClass &Known, unsigned Depth, | |||
4553 | const Query &Q, | |||
4554 | const TargetLibraryInfo *TLI) { | |||
4555 | if ((InterestedClasses & fcNan) == fcNone) | |||
4556 | return; | |||
4557 | ||||
4558 | KnownFPClass KnownSrc; | |||
4559 | computeKnownFPClass(Op->getOperand(0), DemandedElts, InterestedClasses, | |||
4560 | KnownSrc, Depth + 1, Q, TLI); | |||
4561 | if (KnownSrc.isKnownNeverNaN()) | |||
4562 | Known.knownNot(fcNan); | |||
4563 | ||||
4564 | // Infinity needs a range check. | |||
4565 | // TODO: Sign bit should be preserved | |||
4566 | } | |||
4567 | ||||
4568 | // TODO: Merge implementations of isKnownNeverNaN, isKnownNeverInfinity, | |||
4569 | // CannotBeNegativeZero, cannotBeOrderedLessThanZero into here. | |||
4570 | ||||
4571 | void computeKnownFPClass(const Value *V, const APInt &DemandedElts, | |||
4572 | FPClassTest InterestedClasses, KnownFPClass &Known, | |||
4573 | unsigned Depth, const Query &Q, | |||
4574 | const TargetLibraryInfo *TLI) { | |||
4575 | assert(Known.isUnknown() && "should not be called with known information")(static_cast <bool> (Known.isUnknown() && "should not be called with known information" ) ? void (0) : __assert_fail ("Known.isUnknown() && \"should not be called with known information\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4575, __extension__ __PRETTY_FUNCTION__ )); | |||
4576 | ||||
4577 | if (!DemandedElts) { | |||
4578 | // No demanded elts, better to assume we don't know anything. | |||
4579 | Known.resetAll(); | |||
4580 | return; | |||
4581 | } | |||
4582 | ||||
4583 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "llvm/lib/Analysis/ValueTracking.cpp", 4583, __extension__ __PRETTY_FUNCTION__ )); | |||
4584 | ||||
4585 | if (auto *CFP = dyn_cast_or_null<ConstantFP>(V)) { | |||
4586 | Known.KnownFPClasses = CFP->getValueAPF().classify(); | |||
4587 | Known.SignBit = CFP->isNegative(); | |||
4588 | return; | |||
4589 | } | |||
4590 | ||||
4591 | // Try to handle fixed width vector constants | |||
4592 | auto *VFVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
4593 | const Constant *CV = dyn_cast<Constant>(V); | |||
4594 | if (VFVTy && CV) { | |||
4595 | Known.KnownFPClasses = fcNone; | |||
4596 | ||||
4597 | // For vectors, verify that each element is not NaN. | |||
4598 | unsigned NumElts = VFVTy->getNumElements(); | |||
4599 | for (unsigned i = 0; i != NumElts; ++i) { | |||
4600 | Constant *Elt = CV->getAggregateElement(i); | |||
4601 | if (!Elt) { | |||
4602 | Known = KnownFPClass(); | |||
4603 | return; | |||
4604 | } | |||
4605 | if (isa<UndefValue>(Elt)) | |||
4606 | continue; | |||
4607 | auto *CElt = dyn_cast<ConstantFP>(Elt); | |||
4608 | if (!CElt) { | |||
4609 | Known = KnownFPClass(); | |||
4610 | return; | |||
4611 | } | |||
4612 | ||||
4613 | KnownFPClass KnownElt{CElt->getValueAPF().classify(), CElt->isNegative()}; | |||
4614 | Known |= KnownElt; | |||
4615 | } | |||
4616 | ||||
4617 | return; | |||
4618 | } | |||
4619 | ||||
4620 | FPClassTest KnownNotFromFlags = fcNone; | |||
4621 | if (const auto *CB = dyn_cast<CallBase>(V)) | |||
4622 | KnownNotFromFlags |= CB->getRetNoFPClass(); | |||
4623 | else if (const auto *Arg = dyn_cast<Argument>(V)) | |||
4624 | KnownNotFromFlags |= Arg->getNoFPClass(); | |||
4625 | ||||
4626 | const Operator *Op = dyn_cast<Operator>(V); | |||
4627 | if (const FPMathOperator *FPOp = dyn_cast_or_null<FPMathOperator>(Op)) { | |||
4628 | if (FPOp->hasNoNaNs()) | |||
4629 | KnownNotFromFlags |= fcNan; | |||
4630 | if (FPOp->hasNoInfs()) | |||
4631 | KnownNotFromFlags |= fcInf; | |||
4632 | } | |||
4633 | ||||
4634 | if (Q.AC) { | |||
4635 | FPClassTest AssumedClasses = computeKnownFPClassFromAssumes(V, Q); | |||
4636 | KnownNotFromFlags |= ~AssumedClasses; | |||
4637 | } | |||
4638 | ||||
4639 | // We no longer need to find out about these bits from inputs if we can | |||
4640 | // assume this from flags/attributes. | |||
4641 | InterestedClasses &= ~KnownNotFromFlags; | |||
4642 | ||||
4643 | auto ClearClassesFromFlags = make_scope_exit([=, &Known] { | |||
4644 | Known.knownNot(KnownNotFromFlags); | |||
4645 | }); | |||
4646 | ||||
4647 | if (!Op) | |||
4648 | return; | |||
4649 | ||||
4650 | // All recursive calls that increase depth must come after this. | |||
4651 | if (Depth == MaxAnalysisRecursionDepth) | |||
4652 | return; | |||
4653 | ||||
4654 | const unsigned Opc = Op->getOpcode(); | |||
4655 | switch (Opc) { | |||
4656 | case Instruction::FNeg: { | |||
4657 | computeKnownFPClass(Op->getOperand(0), DemandedElts, InterestedClasses, | |||
4658 | Known, Depth + 1, Q, TLI); | |||
4659 | Known.fneg(); | |||
4660 | break; | |||
4661 | } | |||
4662 | case Instruction::Select: { | |||
4663 | KnownFPClass Known2; | |||
4664 | computeKnownFPClass(Op->getOperand(1), DemandedElts, InterestedClasses, | |||
4665 | Known, Depth + 1, Q, TLI); | |||
4666 | computeKnownFPClass(Op->getOperand(2), DemandedElts, InterestedClasses, | |||
4667 | Known2, Depth + 1, Q, TLI); | |||
4668 | Known |= Known2; | |||
4669 | break; | |||
4670 | } | |||
4671 | case Instruction::Call: { | |||
4672 | if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op)) { | |||
4673 | const Intrinsic::ID IID = II->getIntrinsicID(); | |||
4674 | switch (IID) { | |||
4675 | case Intrinsic::fabs: { | |||
4676 | if ((InterestedClasses & (fcNan | fcPositive)) != fcNone) { | |||
4677 | // If we only care about the sign bit we don't need to inspect the | |||
4678 | // operand. | |||
4679 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, | |||
4680 | InterestedClasses, Known, Depth + 1, Q, TLI); | |||
4681 | } | |||
4682 | ||||
4683 | Known.fabs(); | |||
4684 | break; | |||
4685 | } | |||
4686 | case Intrinsic::copysign: { | |||
4687 | KnownFPClass KnownSign; | |||
4688 | ||||
4689 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, | |||
4690 | InterestedClasses, Known, Depth + 1, Q, TLI); | |||
4691 | computeKnownFPClass(II->getArgOperand(1), DemandedElts, | |||
4692 | InterestedClasses, KnownSign, Depth + 1, Q, TLI); | |||
4693 | Known.copysign(KnownSign); | |||
4694 | break; | |||
4695 | } | |||
4696 | case Intrinsic::fma: | |||
4697 | case Intrinsic::fmuladd: { | |||
4698 | if ((InterestedClasses & fcNegative) == fcNone) | |||
4699 | break; | |||
4700 | ||||
4701 | if (II->getArgOperand(0) != II->getArgOperand(1)) | |||
4702 | break; | |||
4703 | ||||
4704 | // The multiply cannot be -0 and therefore the add can't be -0 | |||
4705 | Known.knownNot(fcNegZero); | |||
4706 | ||||
4707 | // x * x + y is non-negative if y is non-negative. | |||
4708 | KnownFPClass KnownAddend; | |||
4709 | computeKnownFPClass(II->getArgOperand(2), DemandedElts, | |||
4710 | InterestedClasses, KnownAddend, Depth + 1, Q, TLI); | |||
4711 | ||||
4712 | // TODO: Known sign bit with no nans | |||
4713 | if (KnownAddend.cannotBeOrderedLessThanZero()) | |||
4714 | Known.knownNot(fcNegative); | |||
4715 | break; | |||
4716 | } | |||
4717 | case Intrinsic::sin: | |||
4718 | case Intrinsic::cos: { | |||
4719 | // Return NaN on infinite inputs. | |||
4720 | KnownFPClass KnownSrc; | |||
4721 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, | |||
4722 | InterestedClasses, KnownSrc, Depth + 1, Q, TLI); | |||
4723 | Known.knownNot(fcInf); | |||
4724 | if (KnownSrc.isKnownNeverNaN() && KnownSrc.isKnownNeverInfinity()) | |||
4725 | Known.knownNot(fcNan); | |||
4726 | break; | |||
4727 | } | |||
4728 | ||||
4729 | case Intrinsic::maxnum: | |||
4730 | case Intrinsic::minnum: | |||
4731 | case Intrinsic::minimum: | |||
4732 | case Intrinsic::maximum: { | |||
4733 | KnownFPClass KnownLHS, KnownRHS; | |||
4734 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, | |||
4735 | InterestedClasses, KnownLHS, Depth + 1, Q, TLI); | |||
4736 | computeKnownFPClass(II->getArgOperand(1), DemandedElts, | |||
4737 | InterestedClasses, KnownRHS, Depth + 1, Q, TLI); | |||
4738 | ||||
4739 | bool NeverNaN = | |||
4740 | KnownLHS.isKnownNeverNaN() || KnownRHS.isKnownNeverNaN(); | |||
4741 | Known = KnownLHS | KnownRHS; | |||
4742 | ||||
4743 | // If either operand is not NaN, the result is not NaN. | |||
4744 | if (NeverNaN && (IID == Intrinsic::minnum || IID == Intrinsic::maxnum)) | |||
4745 | Known.knownNot(fcNan); | |||
4746 | ||||
4747 | if (IID == Intrinsic::maxnum) { | |||
4748 | // If at least one operand is known to be positive, the result must be | |||
4749 | // positive. | |||
4750 | if ((KnownLHS.cannotBeOrderedLessThanZero() && | |||
4751 | KnownLHS.isKnownNeverNaN()) || | |||
4752 | (KnownRHS.cannotBeOrderedLessThanZero() && | |||
4753 | KnownRHS.isKnownNeverNaN())) | |||
4754 | Known.knownNot(KnownFPClass::OrderedLessThanZeroMask); | |||
4755 | } else if (IID == Intrinsic::maximum) { | |||
4756 | // If at least one operand is known to be positive, the result must be | |||
4757 | // positive. | |||
4758 | if (KnownLHS.cannotBeOrderedLessThanZero() || | |||
4759 | KnownRHS.cannotBeOrderedLessThanZero()) | |||
4760 | Known.knownNot(KnownFPClass::OrderedLessThanZeroMask); | |||
4761 | } else if (IID == Intrinsic::minnum) { | |||
4762 | // If at least one operand is known to be negative, the result must be | |||
4763 | // negative. | |||
4764 | if ((KnownLHS.cannotBeOrderedGreaterThanZero() && | |||
4765 | KnownLHS.isKnownNeverNaN()) || | |||
4766 | (KnownRHS.cannotBeOrderedGreaterThanZero() && | |||
4767 | KnownRHS.isKnownNeverNaN())) | |||
4768 | Known.knownNot(KnownFPClass::OrderedGreaterThanZeroMask); | |||
4769 | } else { | |||
4770 | // If at least one operand is known to be negative, the result must be | |||
4771 | // negative. | |||
4772 | if (KnownLHS.cannotBeOrderedGreaterThanZero() || | |||
4773 | KnownRHS.cannotBeOrderedGreaterThanZero()) | |||
4774 | Known.knownNot(KnownFPClass::OrderedGreaterThanZeroMask); | |||
4775 | } | |||
4776 | ||||
4777 | // Fixup zero handling if denormals could be returned as a zero. | |||
4778 | // | |||
4779 | // As there's no spec for denormal flushing, be conservative with the | |||
4780 | // treatment of denormals that could be flushed to zero. For older | |||
4781 | // subtargets on AMDGPU the min/max instructions would not flush the | |||
4782 | // output and return the original value. | |||
4783 | // | |||
4784 | // TODO: This could be refined based on the sign | |||
4785 | if ((Known.KnownFPClasses & fcZero) != fcNone && | |||
4786 | !Known.isKnownNeverSubnormal()) { | |||
4787 | const Function *Parent = II->getFunction(); | |||
4788 | DenormalMode Mode = Parent->getDenormalMode( | |||
4789 | II->getType()->getScalarType()->getFltSemantics()); | |||
4790 | if (Mode != DenormalMode::getIEEE()) | |||
4791 | Known.KnownFPClasses |= fcZero; | |||
4792 | } | |||
4793 | ||||
4794 | break; | |||
4795 | } | |||
4796 | case Intrinsic::canonicalize: { | |||
4797 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, | |||
4798 | InterestedClasses, Known, Depth + 1, Q, TLI); | |||
4799 | // Canonicalize is guaranteed to quiet signaling nans. | |||
4800 | Known.knownNot(fcSNan); | |||
4801 | ||||
4802 | // If the parent function flushes denormals, the canonical output cannot | |||
4803 | // be a denormal. | |||
4804 | const fltSemantics &FPType = II->getType()->getFltSemantics(); | |||
4805 | DenormalMode DenormMode = II->getFunction()->getDenormalMode(FPType); | |||
4806 | if (DenormMode.inputsAreZero() || DenormMode.outputsAreZero()) | |||
4807 | Known.knownNot(fcSubnormal); | |||
4808 | ||||
4809 | if (DenormMode.Input == DenormalMode::PositiveZero || | |||
4810 | (DenormMode.Output == DenormalMode::PositiveZero && | |||
4811 | DenormMode.Input == DenormalMode::IEEE)) | |||
4812 | Known.knownNot(fcNegZero); | |||
4813 | ||||
4814 | break; | |||
4815 | } | |||
4816 | case Intrinsic::trunc: { | |||
4817 | KnownFPClass KnownSrc; | |||
4818 | ||||
4819 | FPClassTest InterestedSrcs = InterestedClasses; | |||
4820 | if (InterestedClasses & fcZero) | |||
4821 | InterestedClasses |= fcNormal | fcSubnormal; | |||
4822 | ||||
4823 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, InterestedSrcs, | |||
4824 | KnownSrc, Depth + 1, Q, TLI); | |||
4825 | ||||
4826 | // Integer results cannot be subnormal. | |||
4827 | Known.knownNot(fcSubnormal); | |||
4828 | ||||
4829 | // trunc passes through infinities. | |||
4830 | if (KnownSrc.isKnownNeverPosInfinity()) | |||
4831 | Known.knownNot(fcPosInf); | |||
4832 | if (KnownSrc.isKnownNeverNegInfinity()) | |||
4833 | Known.knownNot(fcNegInf); | |||
4834 | ||||
4835 | // Non-constrained intrinsics do not guarantee signaling nan quieting. | |||
4836 | if (KnownSrc.isKnownNeverNaN()) | |||
4837 | Known.knownNot(fcNan); | |||
4838 | ||||
4839 | if (KnownSrc.isKnownNever(fcPosNormal)) | |||
4840 | Known.knownNot(fcPosNormal); | |||
4841 | ||||
4842 | if (KnownSrc.isKnownNever(fcNegNormal)) | |||
4843 | Known.knownNot(fcNegNormal); | |||
4844 | ||||
4845 | if (KnownSrc.isKnownNever(fcPosZero | fcPosSubnormal | fcPosNormal)) | |||
4846 | Known.knownNot(fcPosZero); | |||
4847 | ||||
4848 | if (KnownSrc.isKnownNever(fcNegZero | fcNegSubnormal | fcNegNormal)) | |||
4849 | Known.knownNot(fcNegZero); | |||
4850 | ||||
4851 | // Sign should be preserved | |||
4852 | Known.SignBit = KnownSrc.SignBit; | |||
4853 | break; | |||
4854 | } | |||
4855 | case Intrinsic::exp: | |||
4856 | case Intrinsic::exp2: { | |||
4857 | Known.knownNot(fcNegative); | |||
4858 | if ((InterestedClasses & fcNan) == fcNone) | |||
4859 | break; | |||
4860 | ||||
4861 | KnownFPClass KnownSrc; | |||
4862 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, | |||
4863 | InterestedClasses, KnownSrc, Depth + 1, Q, TLI); | |||
4864 | if (KnownSrc.isKnownNeverNaN()) { | |||
4865 | Known.knownNot(fcNan); | |||
4866 | Known.SignBit = false; | |||
4867 | } | |||
4868 | ||||
4869 | break; | |||
4870 | } | |||
4871 | case Intrinsic::fptrunc_round: { | |||
4872 | computeKnownFPClassForFPTrunc(Op, DemandedElts, InterestedClasses, | |||
4873 | Known, Depth, Q, TLI); | |||
4874 | break; | |||
4875 | } | |||
4876 | case Intrinsic::log: | |||
4877 | case Intrinsic::log10: | |||
4878 | case Intrinsic::log2: | |||
4879 | case Intrinsic::experimental_constrained_log: | |||
4880 | case Intrinsic::experimental_constrained_log10: | |||
4881 | case Intrinsic::experimental_constrained_log2: { | |||
4882 | // log(+inf) -> +inf | |||
4883 | // log([+-]0.0) -> -inf | |||
4884 | // log(-inf) -> nan | |||
4885 | // log(-x) -> nan | |||
4886 | if ((InterestedClasses & (fcNan | fcInf)) == fcNone) | |||
4887 | break; | |||
4888 | ||||
4889 | FPClassTest InterestedSrcs = InterestedClasses; | |||
4890 | if ((InterestedClasses & fcNegInf) != fcNone) | |||
4891 | InterestedSrcs |= fcZero | fcSubnormal; | |||
4892 | if ((InterestedClasses & fcNan) != fcNone) | |||
4893 | InterestedSrcs |= fcNan | (fcNegative & ~fcNan); | |||
4894 | ||||
4895 | KnownFPClass KnownSrc; | |||
4896 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, InterestedSrcs, | |||
4897 | KnownSrc, Depth + 1, Q, TLI); | |||
4898 | ||||
4899 | if (KnownSrc.isKnownNeverPosInfinity()) | |||
4900 | Known.knownNot(fcPosInf); | |||
4901 | ||||
4902 | if (KnownSrc.isKnownNeverNaN() && | |||
4903 | KnownSrc.cannotBeOrderedLessThanZero()) | |||
4904 | Known.knownNot(fcNan); | |||
4905 | ||||
4906 | if (KnownSrc.isKnownNeverLogicalZero(*II->getFunction(), II->getType())) | |||
4907 | Known.knownNot(fcNegInf); | |||
4908 | ||||
4909 | break; | |||
4910 | } | |||
4911 | case Intrinsic::powi: { | |||
4912 | if ((InterestedClasses & fcNegative) == fcNone) | |||
4913 | break; | |||
4914 | ||||
4915 | const Value *Exp = II->getArgOperand(1); | |||
4916 | unsigned BitWidth = | |||
4917 | Exp->getType()->getScalarType()->getIntegerBitWidth(); | |||
4918 | KnownBits ExponentKnownBits(BitWidth); | |||
4919 | computeKnownBits(Exp, DemandedElts, ExponentKnownBits, Depth + 1, Q); | |||
4920 | ||||
4921 | if (ExponentKnownBits.Zero[0]) { // Is even | |||
4922 | Known.knownNot(fcNegative); | |||
4923 | break; | |||
4924 | } | |||
4925 | ||||
4926 | // Given that exp is an integer, here are the | |||
4927 | // ways that pow can return a negative value: | |||
4928 | // | |||
4929 | // pow(-x, exp) --> negative if exp is odd and x is negative. | |||
4930 | // pow(-0, exp) --> -inf if exp is negative odd. | |||
4931 | // pow(-0, exp) --> -0 if exp is positive odd. | |||
4932 | // pow(-inf, exp) --> -0 if exp is negative odd. | |||
4933 | // pow(-inf, exp) --> -inf if exp is positive odd. | |||
4934 | KnownFPClass KnownSrc; | |||
4935 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, fcNegative, | |||
4936 | KnownSrc, Depth + 1, Q, TLI); | |||
4937 | if (KnownSrc.isKnownNever(fcNegative)) | |||
4938 | Known.knownNot(fcNegative); | |||
4939 | break; | |||
4940 | } | |||
4941 | case Intrinsic::arithmetic_fence: { | |||
4942 | computeKnownFPClass(II->getArgOperand(0), DemandedElts, | |||
4943 | InterestedClasses, Known, Depth + 1, Q, TLI); | |||
4944 | break; | |||
4945 | } | |||
4946 | case Intrinsic::experimental_constrained_sitofp: | |||
4947 | case Intrinsic::experimental_constrained_uitofp: | |||
4948 | // Cannot produce nan | |||
4949 | Known.knownNot(fcNan); | |||
4950 | ||||
4951 | // sitofp and uitofp turn into +0.0 for zero. | |||
4952 | Known.knownNot(fcNegZero); | |||
4953 | ||||
4954 | // Integers cannot be subnormal | |||
4955 | Known.knownNot(fcSubnormal); | |||
4956 | ||||
4957 | if (IID == Intrinsic::experimental_constrained_uitofp) | |||
4958 | Known.signBitMustBeZero(); | |||
4959 | ||||
4960 | // TODO: Copy inf handling from instructions | |||
4961 | break; | |||
4962 | default: | |||
4963 | break; | |||
4964 | } | |||
4965 | } | |||
4966 | ||||
4967 | break; | |||
4968 | } | |||
4969 | case Instruction::FAdd: | |||
4970 | case Instruction::FSub: { | |||
4971 | KnownFPClass KnownLHS, KnownRHS; | |||
4972 | computeKnownFPClass(Op->getOperand(1), DemandedElts, fcNan | fcInf, | |||
4973 | KnownRHS, Depth + 1, Q, TLI); | |||
4974 | if (KnownRHS.isKnownNeverNaN()) { | |||
4975 | // RHS is canonically cheaper to compute. Skip inspecting the LHS if | |||
4976 | // there's no point. | |||
4977 | computeKnownFPClass(Op->getOperand(0), DemandedElts, fcNan | fcInf, | |||
4978 | KnownLHS, Depth + 1, Q, TLI); | |||
4979 | // Adding positive and negative infinity produces NaN. | |||
4980 | // TODO: Check sign of infinities. | |||
4981 | if (KnownLHS.isKnownNeverNaN() && | |||
4982 | (KnownLHS.isKnownNeverInfinity() || KnownRHS.isKnownNeverInfinity())) | |||
4983 | Known.knownNot(fcNan); | |||
4984 | } | |||
4985 | ||||
4986 | break; | |||
4987 | } | |||
4988 | case Instruction::FMul: { | |||
4989 | // X * X is always non-negative or a NaN. | |||
4990 | if (Op->getOperand(0) == Op->getOperand(1)) | |||
4991 | Known.knownNot(fcNegative); | |||
4992 | ||||
4993 | if ((InterestedClasses & fcNan) != fcNan) | |||
4994 | break; | |||
4995 | ||||
4996 | KnownFPClass KnownLHS, KnownRHS; | |||
4997 | computeKnownFPClass(Op->getOperand(1), DemandedElts, | |||
4998 | fcNan | fcInf | fcZero | fcSubnormal, KnownRHS, | |||
4999 | Depth + 1, Q, TLI); | |||
5000 | if (KnownRHS.isKnownNeverNaN() && | |||
5001 | (KnownRHS.isKnownNeverInfinity() || KnownRHS.isKnownNeverZero())) { | |||
5002 | computeKnownFPClass(Op->getOperand(0), DemandedElts, | |||
5003 | fcNan | fcInf | fcZero, KnownLHS, Depth + 1, Q, TLI); | |||
5004 | if (!KnownLHS.isKnownNeverNaN()) | |||
5005 | break; | |||
5006 | ||||
5007 | const Function *F = cast<Instruction>(Op)->getFunction(); | |||
5008 | ||||
5009 | // If neither side can be zero (or nan) fmul never produces NaN. | |||
5010 | // TODO: Check operand combinations. | |||
5011 | // e.g. fmul nofpclass(inf nan zero), nofpclass(nan) -> nofpclass(nan) | |||
5012 | if ((KnownLHS.isKnownNeverInfinity() || | |||
5013 | KnownLHS.isKnownNeverLogicalZero(*F, Op->getType())) && | |||
5014 | (KnownRHS.isKnownNeverInfinity() || | |||
5015 | KnownRHS.isKnownNeverLogicalZero(*F, Op->getType()))) | |||
5016 | Known.knownNot(fcNan); | |||
5017 | } | |||
5018 | ||||
5019 | break; | |||
5020 | } | |||
5021 | case Instruction::FDiv: | |||
5022 | case Instruction::FRem: { | |||
5023 | if (Op->getOperand(0) == Op->getOperand(1)) { | |||
5024 | // TODO: Could filter out snan if we inspect the operand | |||
5025 | if (Op->getOpcode() == Instruction::FDiv) { | |||
5026 | // X / X is always exactly 1.0 or a NaN. | |||
5027 | Known.KnownFPClasses = fcNan | fcPosNormal; | |||
5028 | } else { | |||
5029 | // X % X is always exactly [+-]0.0 or a NaN. | |||
5030 | Known.KnownFPClasses = fcNan | fcZero; | |||
5031 | } | |||
5032 | ||||
5033 | break; | |||
5034 | } | |||
5035 | ||||
5036 | const bool WantNan = (InterestedClasses & fcNan) != fcNone; | |||
5037 | const bool WantNegative = (InterestedClasses & fcNegative) != fcNone; | |||
5038 | const bool WantPositive = | |||
5039 | Opc == Instruction::FRem && (InterestedClasses & fcPositive) != fcNone; | |||
5040 | if (!WantNan && !WantNegative && !WantPositive) | |||
5041 | break; | |||
5042 | ||||
5043 | KnownFPClass KnownLHS, KnownRHS; | |||
5044 | ||||
5045 | computeKnownFPClass(Op->getOperand(1), DemandedElts, | |||
5046 | fcNan | fcInf | fcZero | fcNegative, KnownRHS, | |||
5047 | Depth + 1, Q, TLI); | |||
5048 | ||||
5049 | bool KnowSomethingUseful = | |||
5050 | KnownRHS.isKnownNeverNaN() || KnownRHS.isKnownNever(fcNegative); | |||
5051 | ||||
5052 | if (KnowSomethingUseful || WantPositive) { | |||
5053 | const FPClassTest InterestedLHS = | |||
5054 | WantPositive ? fcAllFlags | |||
5055 | : fcNan | fcInf | fcZero | fcSubnormal | fcNegative; | |||
5056 | ||||
5057 | computeKnownFPClass(Op->getOperand(0), DemandedElts, | |||
5058 | InterestedClasses & InterestedLHS, KnownLHS, | |||
5059 | Depth + 1, Q, TLI); | |||
5060 | } | |||
5061 | ||||
5062 | const Function *F = cast<Instruction>(Op)->getFunction(); | |||
5063 | ||||
5064 | if (Op->getOpcode() == Instruction::FDiv) { | |||
5065 | // Only 0/0, Inf/Inf produce NaN. | |||
5066 | if (KnownLHS.isKnownNeverNaN() && KnownRHS.isKnownNeverNaN() && | |||
5067 | (KnownLHS.isKnownNeverInfinity() || | |||
5068 | KnownRHS.isKnownNeverInfinity()) && | |||
5069 | (KnownLHS.isKnownNeverLogicalZero(*F, Op->getType()) || | |||
5070 | KnownRHS.isKnownNeverLogicalZero(*F, Op->getType()))) { | |||
5071 | Known.knownNot(fcNan); | |||
5072 | } | |||
5073 | ||||
5074 | // X / -0.0 is -Inf (or NaN). | |||
5075 | // +X / +X is +X | |||
5076 | if (KnownLHS.isKnownNever(fcNegative) && KnownRHS.isKnownNever(fcNegative)) | |||
5077 | Known.knownNot(fcNegative); | |||
5078 | } else { | |||
5079 | // Inf REM x and x REM 0 produce NaN. | |||
5080 | if (KnownLHS.isKnownNeverNaN() && KnownRHS.isKnownNeverNaN() && | |||
5081 | KnownLHS.isKnownNeverInfinity() && | |||
5082 | KnownRHS.isKnownNeverLogicalZero(*F, Op->getType())) { | |||
5083 | Known.knownNot(fcNan); | |||
5084 | } | |||
5085 | ||||
5086 | // The sign for frem is the same as the first operand. | |||
5087 | if (KnownLHS.isKnownNever(fcNegative)) | |||
5088 | Known.knownNot(fcNegative); | |||
5089 | if (KnownLHS.isKnownNever(fcPositive)) | |||
5090 | Known.knownNot(fcPositive); | |||
5091 | } | |||
5092 | ||||
5093 | break; | |||
5094 | } | |||
5095 | case Instruction::FPExt: { | |||
5096 | // Infinity, nan and zero propagate from source. | |||
5097 | computeKnownFPClass(Op->getOperand(0), DemandedElts, InterestedClasses, | |||
5098 | Known, Depth + 1, Q, TLI); | |||
5099 | ||||
5100 | const fltSemantics &DstTy = | |||
5101 | Op->getType()->getScalarType()->getFltSemantics(); | |||
5102 | const fltSemantics &SrcTy = | |||
5103 | Op->getOperand(0)->getType()->getScalarType()->getFltSemantics(); | |||
5104 | ||||
5105 | // All subnormal inputs should be in the normal range in the result type. | |||
5106 | if (APFloat::isRepresentableAsNormalIn(SrcTy, DstTy)) | |||
5107 | Known.knownNot(fcSubnormal); | |||
5108 | ||||
5109 | // Sign bit of a nan isn't guaranteed. | |||
5110 | if (!Known.isKnownNeverNaN()) | |||
5111 | Known.SignBit = std::nullopt; | |||
5112 | break; | |||
5113 | } | |||
5114 | case Instruction::FPTrunc: { | |||
5115 | computeKnownFPClassForFPTrunc(Op, DemandedElts, InterestedClasses, Known, | |||
5116 | Depth, Q, TLI); | |||
5117 | break; | |||
5118 | } | |||
5119 | case Instruction::SIToFP: | |||
5120 | case Instruction::UIToFP: { | |||
5121 | // Cannot produce nan | |||
5122 | Known.knownNot(fcNan); | |||
5123 | ||||
5124 | // Integers cannot be subnormal | |||
5125 | Known.knownNot(fcSubnormal); | |||
5126 | ||||
5127 | // sitofp and uitofp turn into +0.0 for zero. | |||
5128 | Known.knownNot(fcNegZero); | |||
5129 | if (Op->getOpcode() == Instruction::UIToFP) | |||
5130 | Known.signBitMustBeZero(); | |||
5131 | ||||
5132 | if (InterestedClasses & fcInf) { | |||
5133 | // Get width of largest magnitude integer (remove a bit if signed). | |||
5134 | // This still works for a signed minimum value because the largest FP | |||
5135 | // value is scaled by some fraction close to 2.0 (1.0 + 0.xxxx). | |||
5136 | int IntSize = Op->getOperand(0)->getType()->getScalarSizeInBits(); | |||
5137 | if (Op->getOpcode() == Instruction::SIToFP) | |||
5138 | --IntSize; | |||
5139 | ||||
5140 | // If the exponent of the largest finite FP value can hold the largest | |||
5141 | // integer, the result of the cast must be finite. | |||
5142 | Type *FPTy = Op->getType()->getScalarType(); | |||
5143 | if (ilogb(APFloat::getLargest(FPTy->getFltSemantics())) >= IntSize) | |||
5144 | Known.knownNot(fcInf); | |||
5145 | } | |||
5146 | ||||
5147 | break; | |||
5148 | } | |||
5149 | case Instruction::ExtractElement: { | |||
5150 | // Look through extract element. If the index is non-constant or | |||
5151 | // out-of-range demand all elements, otherwise just the extracted element. | |||
5152 | const Value *Vec = Op->getOperand(0); | |||
5153 | const Value *Idx = Op->getOperand(1); | |||
5154 | auto *CIdx = dyn_cast<ConstantInt>(Idx); | |||
5155 | ||||
5156 | if (auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType())) { | |||
5157 | unsigned NumElts = VecTy->getNumElements(); | |||
5158 | APInt DemandedVecElts = APInt::getAllOnes(NumElts); | |||
5159 | if (CIdx && CIdx->getValue().ult(NumElts)) | |||
5160 | DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue()); | |||
5161 | return computeKnownFPClass(Vec, DemandedVecElts, InterestedClasses, Known, | |||
5162 | Depth + 1, Q, TLI); | |||
5163 | } | |||
5164 | ||||
5165 | break; | |||
5166 | } | |||
5167 | case Instruction::InsertElement: { | |||
5168 | if (isa<ScalableVectorType>(Op->getType())) | |||
5169 | return; | |||
5170 | ||||
5171 | const Value *Vec = Op->getOperand(0); | |||
5172 | const Value *Elt = Op->getOperand(1); | |||
5173 | auto *CIdx = dyn_cast<ConstantInt>(Op->getOperand(2)); | |||
5174 | // Early out if the index is non-constant or out-of-range. | |||
5175 | unsigned NumElts = DemandedElts.getBitWidth(); | |||
5176 | if (!CIdx || CIdx->getValue().uge(NumElts)) | |||
5177 | return; | |||
5178 | ||||
5179 | unsigned EltIdx = CIdx->getZExtValue(); | |||
5180 | // Do we demand the inserted element? | |||
5181 | if (DemandedElts[EltIdx]) { | |||
5182 | computeKnownFPClass(Elt, Known, InterestedClasses, Depth + 1, Q, TLI); | |||
5183 | // If we don't know any bits, early out. | |||
5184 | if (Known.isUnknown()) | |||
5185 | break; | |||
5186 | } else { | |||
5187 | Known.KnownFPClasses = fcNone; | |||
5188 | } | |||
5189 | ||||
5190 | // We don't need the base vector element that has been inserted. | |||
5191 | APInt DemandedVecElts = DemandedElts; | |||
5192 | DemandedVecElts.clearBit(EltIdx); | |||
5193 | if (!!DemandedVecElts) { | |||
5194 | KnownFPClass Known2; | |||
5195 | computeKnownFPClass(Vec, DemandedVecElts, InterestedClasses, Known2, | |||
5196 | Depth + 1, Q, TLI); | |||
5197 | Known |= Known2; | |||
5198 | } | |||
5199 | ||||
5200 | break; | |||
5201 | } | |||
5202 | case Instruction::ShuffleVector: { | |||
5203 | // For undef elements, we don't know anything about the common state of | |||
5204 | // the shuffle result. | |||
5205 | APInt DemandedLHS, DemandedRHS; | |||
5206 | auto *Shuf = dyn_cast<ShuffleVectorInst>(Op); | |||
5207 | if (!Shuf || !getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) | |||
5208 | return; | |||
5209 | ||||
5210 | if (!!DemandedLHS) { | |||
5211 | const Value *LHS = Shuf->getOperand(0); | |||
5212 | computeKnownFPClass(LHS, DemandedLHS, InterestedClasses, Known, | |||
5213 | Depth + 1, Q, TLI); | |||
5214 | ||||
5215 | // If we don't know any bits, early out. | |||
5216 | if (Known.isUnknown()) | |||
5217 | break; | |||
5218 | } else { | |||
5219 | Known.KnownFPClasses = fcNone; | |||
5220 | } | |||
5221 | ||||
5222 | if (!!DemandedRHS) { | |||
5223 | KnownFPClass Known2; | |||
5224 | const Value *RHS = Shuf->getOperand(1); | |||
5225 | computeKnownFPClass(RHS, DemandedRHS, InterestedClasses, Known2, | |||
5226 | Depth + 1, Q, TLI); | |||
5227 | Known |= Known2; | |||
5228 | } | |||
5229 | ||||
5230 | break; | |||
5231 | } | |||
5232 | case Instruction::ExtractValue: { | |||
5233 | computeKnownFPClass(Op->getOperand(0), DemandedElts, InterestedClasses, | |||
5234 | Known, Depth + 1, Q, TLI); | |||
5235 | break; | |||
5236 | } | |||
5237 | default: | |||
5238 | break; | |||
5239 | } | |||
5240 | } | |||
5241 | ||||
5242 | KnownFPClass llvm::computeKnownFPClass( | |||
5243 | const Value *V, const APInt &DemandedElts, const DataLayout &DL, | |||
5244 | FPClassTest InterestedClasses, unsigned Depth, const TargetLibraryInfo *TLI, | |||
5245 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
5246 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
5247 | KnownFPClass KnownClasses; | |||
5248 | ::computeKnownFPClass(V, DemandedElts, InterestedClasses, KnownClasses, Depth, | |||
5249 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE), | |||
5250 | TLI); | |||
5251 | return KnownClasses; | |||
5252 | } | |||
5253 | ||||
5254 | KnownFPClass | |||
5255 | llvm::computeKnownFPClass(const Value *V, const DataLayout &DL, | |||
5256 | FPClassTest InterestedClasses, unsigned Depth, | |||
5257 | const TargetLibraryInfo *TLI, AssumptionCache *AC, | |||
5258 | const Instruction *CxtI, const DominatorTree *DT, | |||
5259 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
5260 | KnownFPClass Known; | |||
5261 | ::computeKnownFPClass(V, Known, InterestedClasses, Depth, | |||
5262 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE), | |||
5263 | TLI); | |||
5264 | return Known; | |||
5265 | } | |||
5266 | ||||
5267 | Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) { | |||
5268 | ||||
5269 | // All byte-wide stores are splatable, even of arbitrary variables. | |||
5270 | if (V->getType()->isIntegerTy(8)) | |||
5271 | return V; | |||
5272 | ||||
5273 | LLVMContext &Ctx = V->getContext(); | |||
5274 | ||||
5275 | // Undef don't care. | |||
5276 | auto *UndefInt8 = UndefValue::get(Type::getInt8Ty(Ctx)); | |||
5277 | if (isa<UndefValue>(V)) | |||
5278 | return UndefInt8; | |||
5279 | ||||
5280 | // Return Undef for zero-sized type. | |||
5281 | if (!DL.getTypeStoreSize(V->getType()).isNonZero()) | |||
5282 | return UndefInt8; | |||
5283 | ||||
5284 | Constant *C = dyn_cast<Constant>(V); | |||
5285 | if (!C) { | |||
5286 | // Conceptually, we could handle things like: | |||
5287 | // %a = zext i8 %X to i16 | |||
5288 | // %b = shl i16 %a, 8 | |||
5289 | // %c = or i16 %a, %b | |||
5290 | // but until there is an example that actually needs this, it doesn't seem | |||
5291 | // worth worrying about. | |||
5292 | return nullptr; | |||
5293 | } | |||
5294 | ||||
5295 | // Handle 'null' ConstantArrayZero etc. | |||
5296 | if (C->isNullValue()) | |||
5297 | return Constant::getNullValue(Type::getInt8Ty(Ctx)); | |||
5298 | ||||
5299 | // Constant floating-point values can be handled as integer values if the | |||
5300 | // corresponding integer value is "byteable". An important case is 0.0. | |||
5301 | if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) { | |||
5302 | Type *Ty = nullptr; | |||
5303 | if (CFP->getType()->isHalfTy()) | |||
5304 | Ty = Type::getInt16Ty(Ctx); | |||
5305 | else if (CFP->getType()->isFloatTy()) | |||
5306 | Ty = Type::getInt32Ty(Ctx); | |||
5307 | else if (CFP->getType()->isDoubleTy()) | |||
5308 | Ty = Type::getInt64Ty(Ctx); | |||
5309 | // Don't handle long double formats, which have strange constraints. | |||
5310 | return Ty ? isBytewiseValue(ConstantExpr::getBitCast(CFP, Ty), DL) | |||
5311 | : nullptr; | |||
5312 | } | |||
5313 | ||||
5314 | // We can handle constant integers that are multiple of 8 bits. | |||
5315 | if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { | |||
5316 | if (CI->getBitWidth() % 8 == 0) { | |||
5317 | assert(CI->getBitWidth() > 8 && "8 bits should be handled above!")(static_cast <bool> (CI->getBitWidth() > 8 && "8 bits should be handled above!") ? void (0) : __assert_fail ("CI->getBitWidth() > 8 && \"8 bits should be handled above!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5317, __extension__ __PRETTY_FUNCTION__ )); | |||
5318 | if (!CI->getValue().isSplat(8)) | |||
5319 | return nullptr; | |||
5320 | return ConstantInt::get(Ctx, CI->getValue().trunc(8)); | |||
5321 | } | |||
5322 | } | |||
5323 | ||||
5324 | if (auto *CE = dyn_cast<ConstantExpr>(C)) { | |||
5325 | if (CE->getOpcode() == Instruction::IntToPtr) { | |||
5326 | if (auto *PtrTy = dyn_cast<PointerType>(CE->getType())) { | |||
5327 | unsigned BitWidth = DL.getPointerSizeInBits(PtrTy->getAddressSpace()); | |||
5328 | return isBytewiseValue( | |||
5329 | ConstantExpr::getIntegerCast(CE->getOperand(0), | |||
5330 | Type::getIntNTy(Ctx, BitWidth), false), | |||
5331 | DL); | |||
5332 | } | |||
5333 | } | |||
5334 | } | |||
5335 | ||||
5336 | auto Merge = [&](Value *LHS, Value *RHS) -> Value * { | |||
5337 | if (LHS == RHS) | |||
5338 | return LHS; | |||
5339 | if (!LHS || !RHS) | |||
5340 | return nullptr; | |||
5341 | if (LHS == UndefInt8) | |||
5342 | return RHS; | |||
5343 | if (RHS == UndefInt8) | |||
5344 | return LHS; | |||
5345 | return nullptr; | |||
5346 | }; | |||
5347 | ||||
5348 | if (ConstantDataSequential *CA = dyn_cast<ConstantDataSequential>(C)) { | |||
5349 | Value *Val = UndefInt8; | |||
5350 | for (unsigned I = 0, E = CA->getNumElements(); I != E; ++I) | |||
5351 | if (!(Val = Merge(Val, isBytewiseValue(CA->getElementAsConstant(I), DL)))) | |||
5352 | return nullptr; | |||
5353 | return Val; | |||
5354 | } | |||
5355 | ||||
5356 | if (isa<ConstantAggregate>(C)) { | |||
5357 | Value *Val = UndefInt8; | |||
5358 | for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) | |||
5359 | if (!(Val = Merge(Val, isBytewiseValue(C->getOperand(I), DL)))) | |||
5360 | return nullptr; | |||
5361 | return Val; | |||
5362 | } | |||
5363 | ||||
5364 | // Don't try to handle the handful of other constants. | |||
5365 | return nullptr; | |||
5366 | } | |||
5367 | ||||
5368 | // This is the recursive version of BuildSubAggregate. It takes a few different | |||
5369 | // arguments. Idxs is the index within the nested struct From that we are | |||
5370 | // looking at now (which is of type IndexedType). IdxSkip is the number of | |||
5371 | // indices from Idxs that should be left out when inserting into the resulting | |||
5372 | // struct. To is the result struct built so far, new insertvalue instructions | |||
5373 | // build on that. | |||
5374 | static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType, | |||
5375 | SmallVectorImpl<unsigned> &Idxs, | |||
5376 | unsigned IdxSkip, | |||
5377 | Instruction *InsertBefore) { | |||
5378 | StructType *STy = dyn_cast<StructType>(IndexedType); | |||
5379 | if (STy) { | |||
5380 | // Save the original To argument so we can modify it | |||
5381 | Value *OrigTo = To; | |||
5382 | // General case, the type indexed by Idxs is a struct | |||
5383 | for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { | |||
5384 | // Process each struct element recursively | |||
5385 | Idxs.push_back(i); | |||
5386 | Value *PrevTo = To; | |||
5387 | To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, | |||
5388 | InsertBefore); | |||
5389 | Idxs.pop_back(); | |||
5390 | if (!To) { | |||
5391 | // Couldn't find any inserted value for this index? Cleanup | |||
5392 | while (PrevTo != OrigTo) { | |||
5393 | InsertValueInst* Del = cast<InsertValueInst>(PrevTo); | |||
5394 | PrevTo = Del->getAggregateOperand(); | |||
5395 | Del->eraseFromParent(); | |||
5396 | } | |||
5397 | // Stop processing elements | |||
5398 | break; | |||
5399 | } | |||
5400 | } | |||
5401 | // If we successfully found a value for each of our subaggregates | |||
5402 | if (To) | |||
5403 | return To; | |||
5404 | } | |||
5405 | // Base case, the type indexed by SourceIdxs is not a struct, or not all of | |||
5406 | // the struct's elements had a value that was inserted directly. In the latter | |||
5407 | // case, perhaps we can't determine each of the subelements individually, but | |||
5408 | // we might be able to find the complete struct somewhere. | |||
5409 | ||||
5410 | // Find the value that is at that particular spot | |||
5411 | Value *V = FindInsertedValue(From, Idxs); | |||
5412 | ||||
5413 | if (!V) | |||
5414 | return nullptr; | |||
5415 | ||||
5416 | // Insert the value in the new (sub) aggregate | |||
5417 | return InsertValueInst::Create(To, V, ArrayRef(Idxs).slice(IdxSkip), "tmp", | |||
5418 | InsertBefore); | |||
5419 | } | |||
5420 | ||||
5421 | // This helper takes a nested struct and extracts a part of it (which is again a | |||
5422 | // struct) into a new value. For example, given the struct: | |||
5423 | // { a, { b, { c, d }, e } } | |||
5424 | // and the indices "1, 1" this returns | |||
5425 | // { c, d }. | |||
5426 | // | |||
5427 | // It does this by inserting an insertvalue for each element in the resulting | |||
5428 | // struct, as opposed to just inserting a single struct. This will only work if | |||
5429 | // each of the elements of the substruct are known (ie, inserted into From by an | |||
5430 | // insertvalue instruction somewhere). | |||
5431 | // | |||
5432 | // All inserted insertvalue instructions are inserted before InsertBefore | |||
5433 | static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range, | |||
5434 | Instruction *InsertBefore) { | |||
5435 | assert(InsertBefore && "Must have someplace to insert!")(static_cast <bool> (InsertBefore && "Must have someplace to insert!" ) ? void (0) : __assert_fail ("InsertBefore && \"Must have someplace to insert!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5435, __extension__ __PRETTY_FUNCTION__ )); | |||
5436 | Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), | |||
5437 | idx_range); | |||
5438 | Value *To = PoisonValue::get(IndexedType); | |||
5439 | SmallVector<unsigned, 10> Idxs(idx_range.begin(), idx_range.end()); | |||
5440 | unsigned IdxSkip = Idxs.size(); | |||
5441 | ||||
5442 | return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); | |||
5443 | } | |||
5444 | ||||
5445 | /// Given an aggregate and a sequence of indices, see if the scalar value | |||
5446 | /// indexed is already around as a register, for example if it was inserted | |||
5447 | /// directly into the aggregate. | |||
5448 | /// | |||
5449 | /// If InsertBefore is not null, this function will duplicate (modified) | |||
5450 | /// insertvalues when a part of a nested struct is extracted. | |||
5451 | Value *llvm::FindInsertedValue(Value *V, ArrayRef<unsigned> idx_range, | |||
5452 | Instruction *InsertBefore) { | |||
5453 | // Nothing to index? Just return V then (this is useful at the end of our | |||
5454 | // recursion). | |||
5455 | if (idx_range.empty()) | |||
5456 | return V; | |||
5457 | // We have indices, so V should have an indexable type. | |||
5458 | assert((V->getType()->isStructTy() || V->getType()->isArrayTy()) &&(static_cast <bool> ((V->getType()->isStructTy() || V->getType()->isArrayTy()) && "Not looking at a struct or array?" ) ? void (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5459, __extension__ __PRETTY_FUNCTION__ )) | |||
5459 | "Not looking at a struct or array?")(static_cast <bool> ((V->getType()->isStructTy() || V->getType()->isArrayTy()) && "Not looking at a struct or array?" ) ? void (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5459, __extension__ __PRETTY_FUNCTION__ )); | |||
5460 | assert(ExtractValueInst::getIndexedType(V->getType(), idx_range) &&(static_cast <bool> (ExtractValueInst::getIndexedType(V ->getType(), idx_range) && "Invalid indices for type?" ) ? void (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5461, __extension__ __PRETTY_FUNCTION__ )) | |||
5461 | "Invalid indices for type?")(static_cast <bool> (ExtractValueInst::getIndexedType(V ->getType(), idx_range) && "Invalid indices for type?" ) ? void (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5461, __extension__ __PRETTY_FUNCTION__ )); | |||
5462 | ||||
5463 | if (Constant *C = dyn_cast<Constant>(V)) { | |||
5464 | C = C->getAggregateElement(idx_range[0]); | |||
5465 | if (!C) return nullptr; | |||
5466 | return FindInsertedValue(C, idx_range.slice(1), InsertBefore); | |||
5467 | } | |||
5468 | ||||
5469 | if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) { | |||
5470 | // Loop the indices for the insertvalue instruction in parallel with the | |||
5471 | // requested indices | |||
5472 | const unsigned *req_idx = idx_range.begin(); | |||
5473 | for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); | |||
5474 | i != e; ++i, ++req_idx) { | |||
5475 | if (req_idx == idx_range.end()) { | |||
5476 | // We can't handle this without inserting insertvalues | |||
5477 | if (!InsertBefore) | |||
5478 | return nullptr; | |||
5479 | ||||
5480 | // The requested index identifies a part of a nested aggregate. Handle | |||
5481 | // this specially. For example, | |||
5482 | // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0 | |||
5483 | // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1 | |||
5484 | // %C = extractvalue {i32, { i32, i32 } } %B, 1 | |||
5485 | // This can be changed into | |||
5486 | // %A = insertvalue {i32, i32 } undef, i32 10, 0 | |||
5487 | // %C = insertvalue {i32, i32 } %A, i32 11, 1 | |||
5488 | // which allows the unused 0,0 element from the nested struct to be | |||
5489 | // removed. | |||
5490 | return BuildSubAggregate(V, ArrayRef(idx_range.begin(), req_idx), | |||
5491 | InsertBefore); | |||
5492 | } | |||
5493 | ||||
5494 | // This insert value inserts something else than what we are looking for. | |||
5495 | // See if the (aggregate) value inserted into has the value we are | |||
5496 | // looking for, then. | |||
5497 | if (*req_idx != *i) | |||
5498 | return FindInsertedValue(I->getAggregateOperand(), idx_range, | |||
5499 | InsertBefore); | |||
5500 | } | |||
5501 | // If we end up here, the indices of the insertvalue match with those | |||
5502 | // requested (though possibly only partially). Now we recursively look at | |||
5503 | // the inserted value, passing any remaining indices. | |||
5504 | return FindInsertedValue(I->getInsertedValueOperand(), | |||
5505 | ArrayRef(req_idx, idx_range.end()), InsertBefore); | |||
5506 | } | |||
5507 | ||||
5508 | if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) { | |||
5509 | // If we're extracting a value from an aggregate that was extracted from | |||
5510 | // something else, we can extract from that something else directly instead. | |||
5511 | // However, we will need to chain I's indices with the requested indices. | |||
5512 | ||||
5513 | // Calculate the number of indices required | |||
5514 | unsigned size = I->getNumIndices() + idx_range.size(); | |||
5515 | // Allocate some space to put the new indices in | |||
5516 | SmallVector<unsigned, 5> Idxs; | |||
5517 | Idxs.reserve(size); | |||
5518 | // Add indices from the extract value instruction | |||
5519 | Idxs.append(I->idx_begin(), I->idx_end()); | |||
5520 | ||||
5521 | // Add requested indices | |||
5522 | Idxs.append(idx_range.begin(), idx_range.end()); | |||
5523 | ||||
5524 | assert(Idxs.size() == size(static_cast <bool> (Idxs.size() == size && "Number of indices added not correct?" ) ? void (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5525, __extension__ __PRETTY_FUNCTION__ )) | |||
5525 | && "Number of indices added not correct?")(static_cast <bool> (Idxs.size() == size && "Number of indices added not correct?" ) ? void (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5525, __extension__ __PRETTY_FUNCTION__ )); | |||
5526 | ||||
5527 | return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore); | |||
5528 | } | |||
5529 | // Otherwise, we don't know (such as, extracting from a function return value | |||
5530 | // or load instruction) | |||
5531 | return nullptr; | |||
5532 | } | |||
5533 | ||||
5534 | bool llvm::isGEPBasedOnPointerToString(const GEPOperator *GEP, | |||
5535 | unsigned CharSize) { | |||
5536 | // Make sure the GEP has exactly three arguments. | |||
5537 | if (GEP->getNumOperands() != 3) | |||
5538 | return false; | |||
5539 | ||||
5540 | // Make sure the index-ee is a pointer to array of \p CharSize integers. | |||
5541 | // CharSize. | |||
5542 | ArrayType *AT = dyn_cast<ArrayType>(GEP->getSourceElementType()); | |||
5543 | if (!AT || !AT->getElementType()->isIntegerTy(CharSize)) | |||
5544 | return false; | |||
5545 | ||||
5546 | // Check to make sure that the first operand of the GEP is an integer and | |||
5547 | // has value 0 so that we are sure we're indexing into the initializer. | |||
5548 | const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1)); | |||
5549 | if (!FirstIdx || !FirstIdx->isZero()) | |||
5550 | return false; | |||
5551 | ||||
5552 | return true; | |||
5553 | } | |||
5554 | ||||
5555 | // If V refers to an initialized global constant, set Slice either to | |||
5556 | // its initializer if the size of its elements equals ElementSize, or, | |||
5557 | // for ElementSize == 8, to its representation as an array of unsiged | |||
5558 | // char. Return true on success. | |||
5559 | // Offset is in the unit "nr of ElementSize sized elements". | |||
5560 | bool llvm::getConstantDataArrayInfo(const Value *V, | |||
5561 | ConstantDataArraySlice &Slice, | |||
5562 | unsigned ElementSize, uint64_t Offset) { | |||
5563 | assert(V && "V should not be null.")(static_cast <bool> (V && "V should not be null." ) ? void (0) : __assert_fail ("V && \"V should not be null.\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5563, __extension__ __PRETTY_FUNCTION__ )); | |||
5564 | assert((ElementSize % 8) == 0 &&(static_cast <bool> ((ElementSize % 8) == 0 && "ElementSize expected to be a multiple of the size of a byte." ) ? void (0) : __assert_fail ("(ElementSize % 8) == 0 && \"ElementSize expected to be a multiple of the size of a byte.\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5565, __extension__ __PRETTY_FUNCTION__ )) | |||
5565 | "ElementSize expected to be a multiple of the size of a byte.")(static_cast <bool> ((ElementSize % 8) == 0 && "ElementSize expected to be a multiple of the size of a byte." ) ? void (0) : __assert_fail ("(ElementSize % 8) == 0 && \"ElementSize expected to be a multiple of the size of a byte.\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5565, __extension__ __PRETTY_FUNCTION__ )); | |||
5566 | unsigned ElementSizeInBytes = ElementSize / 8; | |||
5567 | ||||
5568 | // Drill down into the pointer expression V, ignoring any intervening | |||
5569 | // casts, and determine the identity of the object it references along | |||
5570 | // with the cumulative byte offset into it. | |||
5571 | const GlobalVariable *GV = | |||
5572 | dyn_cast<GlobalVariable>(getUnderlyingObject(V)); | |||
5573 | if (!GV
| |||
5574 | // Fail if V is not based on constant global object. | |||
5575 | return false; | |||
5576 | ||||
5577 | const DataLayout &DL = GV->getParent()->getDataLayout(); | |||
5578 | APInt Off(DL.getIndexTypeSizeInBits(V->getType()), 0); | |||
5579 | ||||
5580 | if (GV != V->stripAndAccumulateConstantOffsets(DL, Off, | |||
5581 | /*AllowNonInbounds*/ true)) | |||
5582 | // Fail if a constant offset could not be determined. | |||
5583 | return false; | |||
5584 | ||||
5585 | uint64_t StartIdx = Off.getLimitedValue(); | |||
5586 | if (StartIdx == UINT64_MAX(18446744073709551615UL)) | |||
5587 | // Fail if the constant offset is excessive. | |||
5588 | return false; | |||
5589 | ||||
5590 | // Off/StartIdx is in the unit of bytes. So we need to convert to number of | |||
5591 | // elements. Simply bail out if that isn't possible. | |||
5592 | if ((StartIdx % ElementSizeInBytes) != 0) | |||
5593 | return false; | |||
5594 | ||||
5595 | Offset += StartIdx / ElementSizeInBytes; | |||
5596 | ConstantDataArray *Array = nullptr; | |||
5597 | ArrayType *ArrayTy = nullptr; | |||
5598 | ||||
5599 | if (GV->getInitializer()->isNullValue()) { | |||
5600 | Type *GVTy = GV->getValueType(); | |||
5601 | uint64_t SizeInBytes = DL.getTypeStoreSize(GVTy).getFixedValue(); | |||
5602 | uint64_t Length = SizeInBytes / ElementSizeInBytes; | |||
5603 | ||||
5604 | Slice.Array = nullptr; | |||
5605 | Slice.Offset = 0; | |||
5606 | // Return an empty Slice for undersized constants to let callers | |||
5607 | // transform even undefined library calls into simpler, well-defined | |||
5608 | // expressions. This is preferable to making the calls although it | |||
5609 | // prevents sanitizers from detecting such calls. | |||
5610 | Slice.Length = Length < Offset ? 0 : Length - Offset; | |||
5611 | return true; | |||
5612 | } | |||
5613 | ||||
5614 | auto *Init = const_cast<Constant *>(GV->getInitializer()); | |||
5615 | if (auto *ArrayInit
| |||
5616 | Type *InitElTy = ArrayInit->getElementType(); | |||
5617 | if (InitElTy->isIntegerTy(ElementSize)) { | |||
5618 | // If Init is an initializer for an array of the expected type | |||
5619 | // and size, use it as is. | |||
5620 | Array = ArrayInit; | |||
5621 | ArrayTy = ArrayInit->getType(); | |||
5622 | } | |||
5623 | } | |||
5624 | ||||
5625 | if (!Array
| |||
5626 | if (ElementSize
| |||
5627 | // TODO: Handle conversions to larger integral types. | |||
5628 | return false; | |||
5629 | ||||
5630 | // Otherwise extract the portion of the initializer starting | |||
5631 | // at Offset as an array of bytes, and reset Offset. | |||
5632 | Init = ReadByteArrayFromGlobal(GV, Offset); | |||
5633 | if (!Init) | |||
5634 | return false; | |||
5635 | ||||
5636 | Offset = 0; | |||
5637 | Array = dyn_cast<ConstantDataArray>(Init); | |||
5638 | ArrayTy = dyn_cast<ArrayType>(Init->getType()); | |||
5639 | } | |||
5640 | ||||
5641 | uint64_t NumElts = ArrayTy->getArrayNumElements(); | |||
| ||||
5642 | if (Offset > NumElts) | |||
5643 | return false; | |||
5644 | ||||
5645 | Slice.Array = Array; | |||
5646 | Slice.Offset = Offset; | |||
5647 | Slice.Length = NumElts - Offset; | |||
5648 | return true; | |||
5649 | } | |||
5650 | ||||
5651 | /// Extract bytes from the initializer of the constant array V, which need | |||
5652 | /// not be a nul-terminated string. On success, store the bytes in Str and | |||
5653 | /// return true. When TrimAtNul is set, Str will contain only the bytes up | |||
5654 | /// to but not including the first nul. Return false on failure. | |||
5655 | bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, | |||
5656 | bool TrimAtNul) { | |||
5657 | ConstantDataArraySlice Slice; | |||
5658 | if (!getConstantDataArrayInfo(V, Slice, 8)) | |||
| ||||
5659 | return false; | |||
5660 | ||||
5661 | if (Slice.Array == nullptr) { | |||
5662 | if (TrimAtNul) { | |||
5663 | // Return a nul-terminated string even for an empty Slice. This is | |||
5664 | // safe because all existing SimplifyLibcalls callers require string | |||
5665 | // arguments and the behavior of the functions they fold is undefined | |||
5666 | // otherwise. Folding the calls this way is preferable to making | |||
5667 | // the undefined library calls, even though it prevents sanitizers | |||
5668 | // from reporting such calls. | |||
5669 | Str = StringRef(); | |||
5670 | return true; | |||
5671 | } | |||
5672 | if (Slice.Length == 1) { | |||
5673 | Str = StringRef("", 1); | |||
5674 | return true; | |||
5675 | } | |||
5676 | // We cannot instantiate a StringRef as we do not have an appropriate string | |||
5677 | // of 0s at hand. | |||
5678 | return false; | |||
5679 | } | |||
5680 | ||||
5681 | // Start out with the entire array in the StringRef. | |||
5682 | Str = Slice.Array->getAsString(); | |||
5683 | // Skip over 'offset' bytes. | |||
5684 | Str = Str.substr(Slice.Offset); | |||
5685 | ||||
5686 | if (TrimAtNul) { | |||
5687 | // Trim off the \0 and anything after it. If the array is not nul | |||
5688 | // terminated, we just return the whole end of string. The client may know | |||
5689 | // some other way that the string is length-bound. | |||
5690 | Str = Str.substr(0, Str.find('\0')); | |||
5691 | } | |||
5692 | return true; | |||
5693 | } | |||
5694 | ||||
5695 | // These next two are very similar to the above, but also look through PHI | |||
5696 | // nodes. | |||
5697 | // TODO: See if we can integrate these two together. | |||
5698 | ||||
5699 | /// If we can compute the length of the string pointed to by | |||
5700 | /// the specified pointer, return 'len+1'. If we can't, return 0. | |||
5701 | static uint64_t GetStringLengthH(const Value *V, | |||
5702 | SmallPtrSetImpl<const PHINode*> &PHIs, | |||
5703 | unsigned CharSize) { | |||
5704 | // Look through noop bitcast instructions. | |||
5705 | V = V->stripPointerCasts(); | |||
5706 | ||||
5707 | // If this is a PHI node, there are two cases: either we have already seen it | |||
5708 | // or we haven't. | |||
5709 | if (const PHINode *PN = dyn_cast<PHINode>(V)) { | |||
5710 | if (!PHIs.insert(PN).second) | |||
5711 | return ~0ULL; // already in the set. | |||
5712 | ||||
5713 | // If it was new, see if all the input strings are the same length. | |||
5714 | uint64_t LenSoFar = ~0ULL; | |||
5715 | for (Value *IncValue : PN->incoming_values()) { | |||
5716 | uint64_t Len = GetStringLengthH(IncValue, PHIs, CharSize); | |||
5717 | if (Len == 0) return 0; // Unknown length -> unknown. | |||
5718 | ||||
5719 | if (Len == ~0ULL) continue; | |||
5720 | ||||
5721 | if (Len != LenSoFar && LenSoFar != ~0ULL) | |||
5722 | return 0; // Disagree -> unknown. | |||
5723 | LenSoFar = Len; | |||
5724 | } | |||
5725 | ||||
5726 | // Success, all agree. | |||
5727 | return LenSoFar; | |||
5728 | } | |||
5729 | ||||
5730 | // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) | |||
5731 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) { | |||
5732 | uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs, CharSize); | |||
5733 | if (Len1 == 0) return 0; | |||
5734 | uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs, CharSize); | |||
5735 | if (Len2 == 0) return 0; | |||
5736 | if (Len1 == ~0ULL) return Len2; | |||
5737 | if (Len2 == ~0ULL) return Len1; | |||
5738 | if (Len1 != Len2) return 0; | |||
5739 | return Len1; | |||
5740 | } | |||
5741 | ||||
5742 | // Otherwise, see if we can read the string. | |||
5743 | ConstantDataArraySlice Slice; | |||
5744 | if (!getConstantDataArrayInfo(V, Slice, CharSize)) | |||
5745 | return 0; | |||
5746 | ||||
5747 | if (Slice.Array == nullptr) | |||
5748 | // Zeroinitializer (including an empty one). | |||
5749 | return 1; | |||
5750 | ||||
5751 | // Search for the first nul character. Return a conservative result even | |||
5752 | // when there is no nul. This is safe since otherwise the string function | |||
5753 | // being folded such as strlen is undefined, and can be preferable to | |||
5754 | // making the undefined library call. | |||
5755 | unsigned NullIndex = 0; | |||
5756 | for (unsigned E = Slice.Length; NullIndex < E; ++NullIndex) { | |||
5757 | if (Slice.Array->getElementAsInteger(Slice.Offset + NullIndex) == 0) | |||
5758 | break; | |||
5759 | } | |||
5760 | ||||
5761 | return NullIndex + 1; | |||
5762 | } | |||
5763 | ||||
5764 | /// If we can compute the length of the string pointed to by | |||
5765 | /// the specified pointer, return 'len+1'. If we can't, return 0. | |||
5766 | uint64_t llvm::GetStringLength(const Value *V, unsigned CharSize) { | |||
5767 | if (!V->getType()->isPointerTy()) | |||
5768 | return 0; | |||
5769 | ||||
5770 | SmallPtrSet<const PHINode*, 32> PHIs; | |||
5771 | uint64_t Len = GetStringLengthH(V, PHIs, CharSize); | |||
5772 | // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return | |||
5773 | // an empty string as a length. | |||
5774 | return Len == ~0ULL ? 1 : Len; | |||
5775 | } | |||
5776 | ||||
5777 | const Value * | |||
5778 | llvm::getArgumentAliasingToReturnedPointer(const CallBase *Call, | |||
5779 | bool MustPreserveNullness) { | |||
5780 | assert(Call &&(static_cast <bool> (Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls" ) ? void (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5781, __extension__ __PRETTY_FUNCTION__ )) | |||
5781 | "getArgumentAliasingToReturnedPointer only works on nonnull calls")(static_cast <bool> (Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls" ) ? void (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5781, __extension__ __PRETTY_FUNCTION__ )); | |||
5782 | if (const Value *RV = Call->getReturnedArgOperand()) | |||
5783 | return RV; | |||
5784 | // This can be used only as a aliasing property. | |||
5785 | if (isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( | |||
5786 | Call, MustPreserveNullness)) | |||
5787 | return Call->getArgOperand(0); | |||
5788 | return nullptr; | |||
5789 | } | |||
5790 | ||||
5791 | bool llvm::isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( | |||
5792 | const CallBase *Call, bool MustPreserveNullness) { | |||
5793 | switch (Call->getIntrinsicID()) { | |||
5794 | case Intrinsic::launder_invariant_group: | |||
5795 | case Intrinsic::strip_invariant_group: | |||
5796 | case Intrinsic::aarch64_irg: | |||
5797 | case Intrinsic::aarch64_tagp: | |||
5798 | return true; | |||
5799 | case Intrinsic::ptrmask: | |||
5800 | return !MustPreserveNullness; | |||
5801 | default: | |||
5802 | return false; | |||
5803 | } | |||
5804 | } | |||
5805 | ||||
5806 | /// \p PN defines a loop-variant pointer to an object. Check if the | |||
5807 | /// previous iteration of the loop was referring to the same object as \p PN. | |||
5808 | static bool isSameUnderlyingObjectInLoop(const PHINode *PN, | |||
5809 | const LoopInfo *LI) { | |||
5810 | // Find the loop-defined value. | |||
5811 | Loop *L = LI->getLoopFor(PN->getParent()); | |||
5812 | if (PN->getNumIncomingValues() != 2) | |||
5813 | return true; | |||
5814 | ||||
5815 | // Find the value from previous iteration. | |||
5816 | auto *PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(0)); | |||
5817 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) | |||
5818 | PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(1)); | |||
5819 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) | |||
5820 | return true; | |||
5821 | ||||
5822 | // If a new pointer is loaded in the loop, the pointer references a different | |||
5823 | // object in every iteration. E.g.: | |||
5824 | // for (i) | |||
5825 | // int *p = a[i]; | |||
5826 | // ... | |||
5827 | if (auto *Load = dyn_cast<LoadInst>(PrevValue)) | |||
5828 | if (!L->isLoopInvariant(Load->getPointerOperand())) | |||
5829 | return false; | |||
5830 | return true; | |||
5831 | } | |||
5832 | ||||
5833 | const Value *llvm::getUnderlyingObject(const Value *V, unsigned MaxLookup) { | |||
5834 | if (!V->getType()->isPointerTy()) | |||
5835 | return V; | |||
5836 | for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { | |||
5837 | if (auto *GEP = dyn_cast<GEPOperator>(V)) { | |||
5838 | V = GEP->getPointerOperand(); | |||
5839 | } else if (Operator::getOpcode(V) == Instruction::BitCast || | |||
5840 | Operator::getOpcode(V) == Instruction::AddrSpaceCast) { | |||
5841 | V = cast<Operator>(V)->getOperand(0); | |||
5842 | if (!V->getType()->isPointerTy()) | |||
5843 | return V; | |||
5844 | } else if (auto *GA = dyn_cast<GlobalAlias>(V)) { | |||
5845 | if (GA->isInterposable()) | |||
5846 | return V; | |||
5847 | V = GA->getAliasee(); | |||
5848 | } else { | |||
5849 | if (auto *PHI = dyn_cast<PHINode>(V)) { | |||
5850 | // Look through single-arg phi nodes created by LCSSA. | |||
5851 | if (PHI->getNumIncomingValues() == 1) { | |||
5852 | V = PHI->getIncomingValue(0); | |||
5853 | continue; | |||
5854 | } | |||
5855 | } else if (auto *Call = dyn_cast<CallBase>(V)) { | |||
5856 | // CaptureTracking can know about special capturing properties of some | |||
5857 | // intrinsics like launder.invariant.group, that can't be expressed with | |||
5858 | // the attributes, but have properties like returning aliasing pointer. | |||
5859 | // Because some analysis may assume that nocaptured pointer is not | |||
5860 | // returned from some special intrinsic (because function would have to | |||
5861 | // be marked with returns attribute), it is crucial to use this function | |||
5862 | // because it should be in sync with CaptureTracking. Not using it may | |||
5863 | // cause weird miscompilations where 2 aliasing pointers are assumed to | |||
5864 | // noalias. | |||
5865 | if (auto *RP = getArgumentAliasingToReturnedPointer(Call, false)) { | |||
5866 | V = RP; | |||
5867 | continue; | |||
5868 | } | |||
5869 | } | |||
5870 | ||||
5871 | return V; | |||
5872 | } | |||
5873 | assert(V->getType()->isPointerTy() && "Unexpected operand type!")(static_cast <bool> (V->getType()->isPointerTy() && "Unexpected operand type!") ? void (0) : __assert_fail ("V->getType()->isPointerTy() && \"Unexpected operand type!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5873, __extension__ __PRETTY_FUNCTION__ )); | |||
5874 | } | |||
5875 | return V; | |||
5876 | } | |||
5877 | ||||
5878 | void llvm::getUnderlyingObjects(const Value *V, | |||
5879 | SmallVectorImpl<const Value *> &Objects, | |||
5880 | LoopInfo *LI, unsigned MaxLookup) { | |||
5881 | SmallPtrSet<const Value *, 4> Visited; | |||
5882 | SmallVector<const Value *, 4> Worklist; | |||
5883 | Worklist.push_back(V); | |||
5884 | do { | |||
5885 | const Value *P = Worklist.pop_back_val(); | |||
5886 | P = getUnderlyingObject(P, MaxLookup); | |||
5887 | ||||
5888 | if (!Visited.insert(P).second) | |||
5889 | continue; | |||
5890 | ||||
5891 | if (auto *SI = dyn_cast<SelectInst>(P)) { | |||
5892 | Worklist.push_back(SI->getTrueValue()); | |||
5893 | Worklist.push_back(SI->getFalseValue()); | |||
5894 | continue; | |||
5895 | } | |||
5896 | ||||
5897 | if (auto *PN = dyn_cast<PHINode>(P)) { | |||
5898 | // If this PHI changes the underlying object in every iteration of the | |||
5899 | // loop, don't look through it. Consider: | |||
5900 | // int **A; | |||
5901 | // for (i) { | |||
5902 | // Prev = Curr; // Prev = PHI (Prev_0, Curr) | |||
5903 | // Curr = A[i]; | |||
5904 | // *Prev, *Curr; | |||
5905 | // | |||
5906 | // Prev is tracking Curr one iteration behind so they refer to different | |||
5907 | // underlying objects. | |||
5908 | if (!LI || !LI->isLoopHeader(PN->getParent()) || | |||
5909 | isSameUnderlyingObjectInLoop(PN, LI)) | |||
5910 | append_range(Worklist, PN->incoming_values()); | |||
5911 | continue; | |||
5912 | } | |||
5913 | ||||
5914 | Objects.push_back(P); | |||
5915 | } while (!Worklist.empty()); | |||
5916 | } | |||
5917 | ||||
5918 | /// This is the function that does the work of looking through basic | |||
5919 | /// ptrtoint+arithmetic+inttoptr sequences. | |||
5920 | static const Value *getUnderlyingObjectFromInt(const Value *V) { | |||
5921 | do { | |||
5922 | if (const Operator *U = dyn_cast<Operator>(V)) { | |||
5923 | // If we find a ptrtoint, we can transfer control back to the | |||
5924 | // regular getUnderlyingObjectFromInt. | |||
5925 | if (U->getOpcode() == Instruction::PtrToInt) | |||
5926 | return U->getOperand(0); | |||
5927 | // If we find an add of a constant, a multiplied value, or a phi, it's | |||
5928 | // likely that the other operand will lead us to the base | |||
5929 | // object. We don't have to worry about the case where the | |||
5930 | // object address is somehow being computed by the multiply, | |||
5931 | // because our callers only care when the result is an | |||
5932 | // identifiable object. | |||
5933 | if (U->getOpcode() != Instruction::Add || | |||
5934 | (!isa<ConstantInt>(U->getOperand(1)) && | |||
5935 | Operator::getOpcode(U->getOperand(1)) != Instruction::Mul && | |||
5936 | !isa<PHINode>(U->getOperand(1)))) | |||
5937 | return V; | |||
5938 | V = U->getOperand(0); | |||
5939 | } else { | |||
5940 | return V; | |||
5941 | } | |||
5942 | assert(V->getType()->isIntegerTy() && "Unexpected operand type!")(static_cast <bool> (V->getType()->isIntegerTy() && "Unexpected operand type!") ? void (0) : __assert_fail ("V->getType()->isIntegerTy() && \"Unexpected operand type!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 5942, __extension__ __PRETTY_FUNCTION__ )); | |||
5943 | } while (true); | |||
5944 | } | |||
5945 | ||||
5946 | /// This is a wrapper around getUnderlyingObjects and adds support for basic | |||
5947 | /// ptrtoint+arithmetic+inttoptr sequences. | |||
5948 | /// It returns false if unidentified object is found in getUnderlyingObjects. | |||
5949 | bool llvm::getUnderlyingObjectsForCodeGen(const Value *V, | |||
5950 | SmallVectorImpl<Value *> &Objects) { | |||
5951 | SmallPtrSet<const Value *, 16> Visited; | |||
5952 | SmallVector<const Value *, 4> Working(1, V); | |||
5953 | do { | |||
5954 | V = Working.pop_back_val(); | |||
5955 | ||||
5956 | SmallVector<const Value *, 4> Objs; | |||
5957 | getUnderlyingObjects(V, Objs); | |||
5958 | ||||
5959 | for (const Value *V : Objs) { | |||
5960 | if (!Visited.insert(V).second) | |||
5961 | continue; | |||
5962 | if (Operator::getOpcode(V) == Instruction::IntToPtr) { | |||
5963 | const Value *O = | |||
5964 | getUnderlyingObjectFromInt(cast<User>(V)->getOperand(0)); | |||
5965 | if (O->getType()->isPointerTy()) { | |||
5966 | Working.push_back(O); | |||
5967 | continue; | |||
5968 | } | |||
5969 | } | |||
5970 | // If getUnderlyingObjects fails to find an identifiable object, | |||
5971 | // getUnderlyingObjectsForCodeGen also fails for safety. | |||
5972 | if (!isIdentifiedObject(V)) { | |||
5973 | Objects.clear(); | |||
5974 | return false; | |||
5975 | } | |||
5976 | Objects.push_back(const_cast<Value *>(V)); | |||
5977 | } | |||
5978 | } while (!Working.empty()); | |||
5979 | return true; | |||
5980 | } | |||
5981 | ||||
5982 | AllocaInst *llvm::findAllocaForValue(Value *V, bool OffsetZero) { | |||
5983 | AllocaInst *Result = nullptr; | |||
5984 | SmallPtrSet<Value *, 4> Visited; | |||
5985 | SmallVector<Value *, 4> Worklist; | |||
5986 | ||||
5987 | auto AddWork = [&](Value *V) { | |||
5988 | if (Visited.insert(V).second) | |||
5989 | Worklist.push_back(V); | |||
5990 | }; | |||
5991 | ||||
5992 | AddWork(V); | |||
5993 | do { | |||
5994 | V = Worklist.pop_back_val(); | |||
5995 | assert(Visited.count(V))(static_cast <bool> (Visited.count(V)) ? void (0) : __assert_fail ("Visited.count(V)", "llvm/lib/Analysis/ValueTracking.cpp", 5995 , __extension__ __PRETTY_FUNCTION__)); | |||
5996 | ||||
5997 | if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) { | |||
5998 | if (Result && Result != AI) | |||
5999 | return nullptr; | |||
6000 | Result = AI; | |||
6001 | } else if (CastInst *CI = dyn_cast<CastInst>(V)) { | |||
6002 | AddWork(CI->getOperand(0)); | |||
6003 | } else if (PHINode *PN = dyn_cast<PHINode>(V)) { | |||
6004 | for (Value *IncValue : PN->incoming_values()) | |||
6005 | AddWork(IncValue); | |||
6006 | } else if (auto *SI = dyn_cast<SelectInst>(V)) { | |||
6007 | AddWork(SI->getTrueValue()); | |||
6008 | AddWork(SI->getFalseValue()); | |||
6009 | } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) { | |||
6010 | if (OffsetZero && !GEP->hasAllZeroIndices()) | |||
6011 | return nullptr; | |||
6012 | AddWork(GEP->getPointerOperand()); | |||
6013 | } else if (CallBase *CB = dyn_cast<CallBase>(V)) { | |||
6014 | Value *Returned = CB->getReturnedArgOperand(); | |||
6015 | if (Returned) | |||
6016 | AddWork(Returned); | |||
6017 | else | |||
6018 | return nullptr; | |||
6019 | } else { | |||
6020 | return nullptr; | |||
6021 | } | |||
6022 | } while (!Worklist.empty()); | |||
6023 | ||||
6024 | return Result; | |||
6025 | } | |||
6026 | ||||
6027 | static bool onlyUsedByLifetimeMarkersOrDroppableInstsHelper( | |||
6028 | const Value *V, bool AllowLifetime, bool AllowDroppable) { | |||
6029 | for (const User *U : V->users()) { | |||
6030 | const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U); | |||
6031 | if (!II) | |||
6032 | return false; | |||
6033 | ||||
6034 | if (AllowLifetime && II->isLifetimeStartOrEnd()) | |||
6035 | continue; | |||
6036 | ||||
6037 | if (AllowDroppable && II->isDroppable()) | |||
6038 | continue; | |||
6039 | ||||
6040 | return false; | |||
6041 | } | |||
6042 | return true; | |||
6043 | } | |||
6044 | ||||
6045 | bool llvm::onlyUsedByLifetimeMarkers(const Value *V) { | |||
6046 | return onlyUsedByLifetimeMarkersOrDroppableInstsHelper( | |||
6047 | V, /* AllowLifetime */ true, /* AllowDroppable */ false); | |||
6048 | } | |||
6049 | bool llvm::onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V) { | |||
6050 | return onlyUsedByLifetimeMarkersOrDroppableInstsHelper( | |||
6051 | V, /* AllowLifetime */ true, /* AllowDroppable */ true); | |||
6052 | } | |||
6053 | ||||
6054 | bool llvm::mustSuppressSpeculation(const LoadInst &LI) { | |||
6055 | if (!LI.isUnordered()) | |||
6056 | return true; | |||
6057 | const Function &F = *LI.getFunction(); | |||
6058 | // Speculative load may create a race that did not exist in the source. | |||
6059 | return F.hasFnAttribute(Attribute::SanitizeThread) || | |||
6060 | // Speculative load may load data from dirty regions. | |||
6061 | F.hasFnAttribute(Attribute::SanitizeAddress) || | |||
6062 | F.hasFnAttribute(Attribute::SanitizeHWAddress); | |||
6063 | } | |||
6064 | ||||
6065 | bool llvm::isSafeToSpeculativelyExecute(const Instruction *Inst, | |||
6066 | const Instruction *CtxI, | |||
6067 | AssumptionCache *AC, | |||
6068 | const DominatorTree *DT, | |||
6069 | const TargetLibraryInfo *TLI) { | |||
6070 | return isSafeToSpeculativelyExecuteWithOpcode(Inst->getOpcode(), Inst, CtxI, | |||
6071 | AC, DT, TLI); | |||
6072 | } | |||
6073 | ||||
6074 | bool llvm::isSafeToSpeculativelyExecuteWithOpcode( | |||
6075 | unsigned Opcode, const Instruction *Inst, const Instruction *CtxI, | |||
6076 | AssumptionCache *AC, const DominatorTree *DT, | |||
6077 | const TargetLibraryInfo *TLI) { | |||
6078 | #ifndef NDEBUG | |||
6079 | if (Inst->getOpcode() != Opcode) { | |||
6080 | // Check that the operands are actually compatible with the Opcode override. | |||
6081 | auto hasEqualReturnAndLeadingOperandTypes = | |||
6082 | [](const Instruction *Inst, unsigned NumLeadingOperands) { | |||
6083 | if (Inst->getNumOperands() < NumLeadingOperands) | |||
6084 | return false; | |||
6085 | const Type *ExpectedType = Inst->getType(); | |||
6086 | for (unsigned ItOp = 0; ItOp < NumLeadingOperands; ++ItOp) | |||
6087 | if (Inst->getOperand(ItOp)->getType() != ExpectedType) | |||
6088 | return false; | |||
6089 | return true; | |||
6090 | }; | |||
6091 | assert(!Instruction::isBinaryOp(Opcode) ||(static_cast <bool> (!Instruction::isBinaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 2)) ? void (0) : __assert_fail ("!Instruction::isBinaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 2)" , "llvm/lib/Analysis/ValueTracking.cpp", 6092, __extension__ __PRETTY_FUNCTION__ )) | |||
6092 | hasEqualReturnAndLeadingOperandTypes(Inst, 2))(static_cast <bool> (!Instruction::isBinaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 2)) ? void (0) : __assert_fail ("!Instruction::isBinaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 2)" , "llvm/lib/Analysis/ValueTracking.cpp", 6092, __extension__ __PRETTY_FUNCTION__ )); | |||
6093 | assert(!Instruction::isUnaryOp(Opcode) ||(static_cast <bool> (!Instruction::isUnaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 1)) ? void (0) : __assert_fail ("!Instruction::isUnaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 1)" , "llvm/lib/Analysis/ValueTracking.cpp", 6094, __extension__ __PRETTY_FUNCTION__ )) | |||
6094 | hasEqualReturnAndLeadingOperandTypes(Inst, 1))(static_cast <bool> (!Instruction::isUnaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 1)) ? void (0) : __assert_fail ("!Instruction::isUnaryOp(Opcode) || hasEqualReturnAndLeadingOperandTypes(Inst, 1)" , "llvm/lib/Analysis/ValueTracking.cpp", 6094, __extension__ __PRETTY_FUNCTION__ )); | |||
6095 | } | |||
6096 | #endif | |||
6097 | ||||
6098 | switch (Opcode) { | |||
6099 | default: | |||
6100 | return true; | |||
6101 | case Instruction::UDiv: | |||
6102 | case Instruction::URem: { | |||
6103 | // x / y is undefined if y == 0. | |||
6104 | const APInt *V; | |||
6105 | if (match(Inst->getOperand(1), m_APInt(V))) | |||
6106 | return *V != 0; | |||
6107 | return false; | |||
6108 | } | |||
6109 | case Instruction::SDiv: | |||
6110 | case Instruction::SRem: { | |||
6111 | // x / y is undefined if y == 0 or x == INT_MIN and y == -1 | |||
6112 | const APInt *Numerator, *Denominator; | |||
6113 | if (!match(Inst->getOperand(1), m_APInt(Denominator))) | |||
6114 | return false; | |||
6115 | // We cannot hoist this division if the denominator is 0. | |||
6116 | if (*Denominator == 0) | |||
6117 | return false; | |||
6118 | // It's safe to hoist if the denominator is not 0 or -1. | |||
6119 | if (!Denominator->isAllOnes()) | |||
6120 | return true; | |||
6121 | // At this point we know that the denominator is -1. It is safe to hoist as | |||
6122 | // long we know that the numerator is not INT_MIN. | |||
6123 | if (match(Inst->getOperand(0), m_APInt(Numerator))) | |||
6124 | return !Numerator->isMinSignedValue(); | |||
6125 | // The numerator *might* be MinSignedValue. | |||
6126 | return false; | |||
6127 | } | |||
6128 | case Instruction::Load: { | |||
6129 | const LoadInst *LI = dyn_cast<LoadInst>(Inst); | |||
6130 | if (!LI) | |||
6131 | return false; | |||
6132 | if (mustSuppressSpeculation(*LI)) | |||
6133 | return false; | |||
6134 | const DataLayout &DL = LI->getModule()->getDataLayout(); | |||
6135 | return isDereferenceableAndAlignedPointer(LI->getPointerOperand(), | |||
6136 | LI->getType(), LI->getAlign(), DL, | |||
6137 | CtxI, AC, DT, TLI); | |||
6138 | } | |||
6139 | case Instruction::Call: { | |||
6140 | auto *CI = dyn_cast<const CallInst>(Inst); | |||
6141 | if (!CI) | |||
6142 | return false; | |||
6143 | const Function *Callee = CI->getCalledFunction(); | |||
6144 | ||||
6145 | // The called function could have undefined behavior or side-effects, even | |||
6146 | // if marked readnone nounwind. | |||
6147 | return Callee && Callee->isSpeculatable(); | |||
6148 | } | |||
6149 | case Instruction::VAArg: | |||
6150 | case Instruction::Alloca: | |||
6151 | case Instruction::Invoke: | |||
6152 | case Instruction::CallBr: | |||
6153 | case Instruction::PHI: | |||
6154 | case Instruction::Store: | |||
6155 | case Instruction::Ret: | |||
6156 | case Instruction::Br: | |||
6157 | case Instruction::IndirectBr: | |||
6158 | case Instruction::Switch: | |||
6159 | case Instruction::Unreachable: | |||
6160 | case Instruction::Fence: | |||
6161 | case Instruction::AtomicRMW: | |||
6162 | case Instruction::AtomicCmpXchg: | |||
6163 | case Instruction::LandingPad: | |||
6164 | case Instruction::Resume: | |||
6165 | case Instruction::CatchSwitch: | |||
6166 | case Instruction::CatchPad: | |||
6167 | case Instruction::CatchRet: | |||
6168 | case Instruction::CleanupPad: | |||
6169 | case Instruction::CleanupRet: | |||
6170 | return false; // Misc instructions which have effects | |||
6171 | } | |||
6172 | } | |||
6173 | ||||
6174 | bool llvm::mayHaveNonDefUseDependency(const Instruction &I) { | |||
6175 | if (I.mayReadOrWriteMemory()) | |||
6176 | // Memory dependency possible | |||
6177 | return true; | |||
6178 | if (!isSafeToSpeculativelyExecute(&I)) | |||
6179 | // Can't move above a maythrow call or infinite loop. Or if an | |||
6180 | // inalloca alloca, above a stacksave call. | |||
6181 | return true; | |||
6182 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
6183 | // 1) Can't reorder two inf-loop calls, even if readonly | |||
6184 | // 2) Also can't reorder an inf-loop call below a instruction which isn't | |||
6185 | // safe to speculative execute. (Inverse of above) | |||
6186 | return true; | |||
6187 | return false; | |||
6188 | } | |||
6189 | ||||
6190 | /// Convert ConstantRange OverflowResult into ValueTracking OverflowResult. | |||
6191 | static OverflowResult mapOverflowResult(ConstantRange::OverflowResult OR) { | |||
6192 | switch (OR) { | |||
6193 | case ConstantRange::OverflowResult::MayOverflow: | |||
6194 | return OverflowResult::MayOverflow; | |||
6195 | case ConstantRange::OverflowResult::AlwaysOverflowsLow: | |||
6196 | return OverflowResult::AlwaysOverflowsLow; | |||
6197 | case ConstantRange::OverflowResult::AlwaysOverflowsHigh: | |||
6198 | return OverflowResult::AlwaysOverflowsHigh; | |||
6199 | case ConstantRange::OverflowResult::NeverOverflows: | |||
6200 | return OverflowResult::NeverOverflows; | |||
6201 | } | |||
6202 | llvm_unreachable("Unknown OverflowResult")::llvm::llvm_unreachable_internal("Unknown OverflowResult", "llvm/lib/Analysis/ValueTracking.cpp" , 6202); | |||
6203 | } | |||
6204 | ||||
6205 | /// Combine constant ranges from computeConstantRange() and computeKnownBits(). | |||
6206 | static ConstantRange computeConstantRangeIncludingKnownBits( | |||
6207 | const Value *V, bool ForSigned, const DataLayout &DL, unsigned Depth, | |||
6208 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
6209 | OptimizationRemarkEmitter *ORE = nullptr, bool UseInstrInfo = true) { | |||
6210 | KnownBits Known = computeKnownBits( | |||
6211 | V, DL, Depth, AC, CxtI, DT, ORE, UseInstrInfo); | |||
6212 | ConstantRange CR1 = ConstantRange::fromKnownBits(Known, ForSigned); | |||
6213 | ConstantRange CR2 = computeConstantRange(V, ForSigned, UseInstrInfo); | |||
6214 | ConstantRange::PreferredRangeType RangeType = | |||
6215 | ForSigned ? ConstantRange::Signed : ConstantRange::Unsigned; | |||
6216 | return CR1.intersectWith(CR2, RangeType); | |||
6217 | } | |||
6218 | ||||
6219 | OverflowResult llvm::computeOverflowForUnsignedMul( | |||
6220 | const Value *LHS, const Value *RHS, const DataLayout &DL, | |||
6221 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
6222 | bool UseInstrInfo) { | |||
6223 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
6224 | nullptr, UseInstrInfo); | |||
6225 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
6226 | nullptr, UseInstrInfo); | |||
6227 | ConstantRange LHSRange = ConstantRange::fromKnownBits(LHSKnown, false); | |||
6228 | ConstantRange RHSRange = ConstantRange::fromKnownBits(RHSKnown, false); | |||
6229 | return mapOverflowResult(LHSRange.unsignedMulMayOverflow(RHSRange)); | |||
6230 | } | |||
6231 | ||||
6232 | OverflowResult | |||
6233 | llvm::computeOverflowForSignedMul(const Value *LHS, const Value *RHS, | |||
6234 | const DataLayout &DL, AssumptionCache *AC, | |||
6235 | const Instruction *CxtI, | |||
6236 | const DominatorTree *DT, bool UseInstrInfo) { | |||
6237 | // Multiplying n * m significant bits yields a result of n + m significant | |||
6238 | // bits. If the total number of significant bits does not exceed the | |||
6239 | // result bit width (minus 1), there is no overflow. | |||
6240 | // This means if we have enough leading sign bits in the operands | |||
6241 | // we can guarantee that the result does not overflow. | |||
6242 | // Ref: "Hacker's Delight" by Henry Warren | |||
6243 | unsigned BitWidth = LHS->getType()->getScalarSizeInBits(); | |||
6244 | ||||
6245 | // Note that underestimating the number of sign bits gives a more | |||
6246 | // conservative answer. | |||
6247 | unsigned SignBits = ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) + | |||
6248 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT); | |||
6249 | ||||
6250 | // First handle the easy case: if we have enough sign bits there's | |||
6251 | // definitely no overflow. | |||
6252 | if (SignBits > BitWidth + 1) | |||
6253 | return OverflowResult::NeverOverflows; | |||
6254 | ||||
6255 | // There are two ambiguous cases where there can be no overflow: | |||
6256 | // SignBits == BitWidth + 1 and | |||
6257 | // SignBits == BitWidth | |||
6258 | // The second case is difficult to check, therefore we only handle the | |||
6259 | // first case. | |||
6260 | if (SignBits == BitWidth + 1) { | |||
6261 | // It overflows only when both arguments are negative and the true | |||
6262 | // product is exactly the minimum negative number. | |||
6263 | // E.g. mul i16 with 17 sign bits: 0xff00 * 0xff80 = 0x8000 | |||
6264 | // For simplicity we just check if at least one side is not negative. | |||
6265 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
6266 | nullptr, UseInstrInfo); | |||
6267 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
6268 | nullptr, UseInstrInfo); | |||
6269 | if (LHSKnown.isNonNegative() || RHSKnown.isNonNegative()) | |||
6270 | return OverflowResult::NeverOverflows; | |||
6271 | } | |||
6272 | return OverflowResult::MayOverflow; | |||
6273 | } | |||
6274 | ||||
6275 | OverflowResult llvm::computeOverflowForUnsignedAdd( | |||
6276 | const Value *LHS, const Value *RHS, const DataLayout &DL, | |||
6277 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
6278 | bool UseInstrInfo) { | |||
6279 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
6280 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, | |||
6281 | nullptr, UseInstrInfo); | |||
6282 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
6283 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, | |||
6284 | nullptr, UseInstrInfo); | |||
6285 | return mapOverflowResult(LHSRange.unsignedAddMayOverflow(RHSRange)); | |||
6286 | } | |||
6287 | ||||
6288 | static OverflowResult computeOverflowForSignedAdd(const Value *LHS, | |||
6289 | const Value *RHS, | |||
6290 | const AddOperator *Add, | |||
6291 | const DataLayout &DL, | |||
6292 | AssumptionCache *AC, | |||
6293 | const Instruction *CxtI, | |||
6294 | const DominatorTree *DT) { | |||
6295 | if (Add && Add->hasNoSignedWrap()) { | |||
6296 | return OverflowResult::NeverOverflows; | |||
6297 | } | |||
6298 | ||||
6299 | // If LHS and RHS each have at least two sign bits, the addition will look | |||
6300 | // like | |||
6301 | // | |||
6302 | // XX..... + | |||
6303 | // YY..... | |||
6304 | // | |||
6305 | // If the carry into the most significant position is 0, X and Y can't both | |||
6306 | // be 1 and therefore the carry out of the addition is also 0. | |||
6307 | // | |||
6308 | // If the carry into the most significant position is 1, X and Y can't both | |||
6309 | // be 0 and therefore the carry out of the addition is also 1. | |||
6310 | // | |||
6311 | // Since the carry into the most significant position is always equal to | |||
6312 | // the carry out of the addition, there is no signed overflow. | |||
6313 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && | |||
6314 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) | |||
6315 | return OverflowResult::NeverOverflows; | |||
6316 | ||||
6317 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
6318 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
6319 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
6320 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
6321 | OverflowResult OR = | |||
6322 | mapOverflowResult(LHSRange.signedAddMayOverflow(RHSRange)); | |||
6323 | if (OR != OverflowResult::MayOverflow) | |||
6324 | return OR; | |||
6325 | ||||
6326 | // The remaining code needs Add to be available. Early returns if not so. | |||
6327 | if (!Add) | |||
6328 | return OverflowResult::MayOverflow; | |||
6329 | ||||
6330 | // If the sign of Add is the same as at least one of the operands, this add | |||
6331 | // CANNOT overflow. If this can be determined from the known bits of the | |||
6332 | // operands the above signedAddMayOverflow() check will have already done so. | |||
6333 | // The only other way to improve on the known bits is from an assumption, so | |||
6334 | // call computeKnownBitsFromAssume() directly. | |||
6335 | bool LHSOrRHSKnownNonNegative = | |||
6336 | (LHSRange.isAllNonNegative() || RHSRange.isAllNonNegative()); | |||
6337 | bool LHSOrRHSKnownNegative = | |||
6338 | (LHSRange.isAllNegative() || RHSRange.isAllNegative()); | |||
6339 | if (LHSOrRHSKnownNonNegative || LHSOrRHSKnownNegative) { | |||
6340 | KnownBits AddKnown(LHSRange.getBitWidth()); | |||
6341 | computeKnownBitsFromAssume( | |||
6342 | Add, AddKnown, /*Depth=*/0, Query(DL, AC, CxtI, DT, true)); | |||
6343 | if ((AddKnown.isNonNegative() && LHSOrRHSKnownNonNegative) || | |||
6344 | (AddKnown.isNegative() && LHSOrRHSKnownNegative)) | |||
6345 | return OverflowResult::NeverOverflows; | |||
6346 | } | |||
6347 | ||||
6348 | return OverflowResult::MayOverflow; | |||
6349 | } | |||
6350 | ||||
6351 | OverflowResult llvm::computeOverflowForUnsignedSub(const Value *LHS, | |||
6352 | const Value *RHS, | |||
6353 | const DataLayout &DL, | |||
6354 | AssumptionCache *AC, | |||
6355 | const Instruction *CxtI, | |||
6356 | const DominatorTree *DT) { | |||
6357 | // X - (X % ?) | |||
6358 | // The remainder of a value can't have greater magnitude than itself, | |||
6359 | // so the subtraction can't overflow. | |||
6360 | ||||
6361 | // X - (X -nuw ?) | |||
6362 | // In the minimal case, this would simplify to "?", so there's no subtract | |||
6363 | // at all. But if this analysis is used to peek through casts, for example, | |||
6364 | // then determining no-overflow may allow other transforms. | |||
6365 | ||||
6366 | // TODO: There are other patterns like this. | |||
6367 | // See simplifyICmpWithBinOpOnLHS() for candidates. | |||
6368 | if (match(RHS, m_URem(m_Specific(LHS), m_Value())) || | |||
6369 | match(RHS, m_NUWSub(m_Specific(LHS), m_Value()))) | |||
6370 | if (isGuaranteedNotToBeUndefOrPoison(LHS, AC, CxtI, DT)) | |||
6371 | return OverflowResult::NeverOverflows; | |||
6372 | ||||
6373 | // Checking for conditions implied by dominating conditions may be expensive. | |||
6374 | // Limit it to usub_with_overflow calls for now. | |||
6375 | if (match(CxtI, | |||
6376 | m_Intrinsic<Intrinsic::usub_with_overflow>(m_Value(), m_Value()))) | |||
6377 | if (auto C = | |||
6378 | isImpliedByDomCondition(CmpInst::ICMP_UGE, LHS, RHS, CxtI, DL)) { | |||
6379 | if (*C) | |||
6380 | return OverflowResult::NeverOverflows; | |||
6381 | return OverflowResult::AlwaysOverflowsLow; | |||
6382 | } | |||
6383 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
6384 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); | |||
6385 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
6386 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); | |||
6387 | return mapOverflowResult(LHSRange.unsignedSubMayOverflow(RHSRange)); | |||
6388 | } | |||
6389 | ||||
6390 | OverflowResult llvm::computeOverflowForSignedSub(const Value *LHS, | |||
6391 | const Value *RHS, | |||
6392 | const DataLayout &DL, | |||
6393 | AssumptionCache *AC, | |||
6394 | const Instruction *CxtI, | |||
6395 | const DominatorTree *DT) { | |||
6396 | // X - (X % ?) | |||
6397 | // The remainder of a value can't have greater magnitude than itself, | |||
6398 | // so the subtraction can't overflow. | |||
6399 | ||||
6400 | // X - (X -nsw ?) | |||
6401 | // In the minimal case, this would simplify to "?", so there's no subtract | |||
6402 | // at all. But if this analysis is used to peek through casts, for example, | |||
6403 | // then determining no-overflow may allow other transforms. | |||
6404 | if (match(RHS, m_SRem(m_Specific(LHS), m_Value())) || | |||
6405 | match(RHS, m_NSWSub(m_Specific(LHS), m_Value()))) | |||
6406 | if (isGuaranteedNotToBeUndefOrPoison(LHS, AC, CxtI, DT)) | |||
6407 | return OverflowResult::NeverOverflows; | |||
6408 | ||||
6409 | // If LHS and RHS each have at least two sign bits, the subtraction | |||
6410 | // cannot overflow. | |||
6411 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && | |||
6412 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) | |||
6413 | return OverflowResult::NeverOverflows; | |||
6414 | ||||
6415 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
6416 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
6417 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
6418 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
6419 | return mapOverflowResult(LHSRange.signedSubMayOverflow(RHSRange)); | |||
6420 | } | |||
6421 | ||||
6422 | bool llvm::isOverflowIntrinsicNoWrap(const WithOverflowInst *WO, | |||
6423 | const DominatorTree &DT) { | |||
6424 | SmallVector<const BranchInst *, 2> GuardingBranches; | |||
6425 | SmallVector<const ExtractValueInst *, 2> Results; | |||
6426 | ||||
6427 | for (const User *U : WO->users()) { | |||
6428 | if (const auto *EVI = dyn_cast<ExtractValueInst>(U)) { | |||
6429 | assert(EVI->getNumIndices() == 1 && "Obvious from CI's type")(static_cast <bool> (EVI->getNumIndices() == 1 && "Obvious from CI's type") ? void (0) : __assert_fail ("EVI->getNumIndices() == 1 && \"Obvious from CI's type\"" , "llvm/lib/Analysis/ValueTracking.cpp", 6429, __extension__ __PRETTY_FUNCTION__ )); | |||
6430 | ||||
6431 | if (EVI->getIndices()[0] == 0) | |||
6432 | Results.push_back(EVI); | |||
6433 | else { | |||
6434 | assert(EVI->getIndices()[0] == 1 && "Obvious from CI's type")(static_cast <bool> (EVI->getIndices()[0] == 1 && "Obvious from CI's type") ? void (0) : __assert_fail ("EVI->getIndices()[0] == 1 && \"Obvious from CI's type\"" , "llvm/lib/Analysis/ValueTracking.cpp", 6434, __extension__ __PRETTY_FUNCTION__ )); | |||
6435 | ||||
6436 | for (const auto *U : EVI->users()) | |||
6437 | if (const auto *B = dyn_cast<BranchInst>(U)) { | |||
6438 | assert(B->isConditional() && "How else is it using an i1?")(static_cast <bool> (B->isConditional() && "How else is it using an i1?" ) ? void (0) : __assert_fail ("B->isConditional() && \"How else is it using an i1?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 6438, __extension__ __PRETTY_FUNCTION__ )); | |||
6439 | GuardingBranches.push_back(B); | |||
6440 | } | |||
6441 | } | |||
6442 | } else { | |||
6443 | // We are using the aggregate directly in a way we don't want to analyze | |||
6444 | // here (storing it to a global, say). | |||
6445 | return false; | |||
6446 | } | |||
6447 | } | |||
6448 | ||||
6449 | auto AllUsesGuardedByBranch = [&](const BranchInst *BI) { | |||
6450 | BasicBlockEdge NoWrapEdge(BI->getParent(), BI->getSuccessor(1)); | |||
6451 | if (!NoWrapEdge.isSingleEdge()) | |||
6452 | return false; | |||
6453 | ||||
6454 | // Check if all users of the add are provably no-wrap. | |||
6455 | for (const auto *Result : Results) { | |||
6456 | // If the extractvalue itself is not executed on overflow, the we don't | |||
6457 | // need to check each use separately, since domination is transitive. | |||
6458 | if (DT.dominates(NoWrapEdge, Result->getParent())) | |||
6459 | continue; | |||
6460 | ||||
6461 | for (const auto &RU : Result->uses()) | |||
6462 | if (!DT.dominates(NoWrapEdge, RU)) | |||
6463 | return false; | |||
6464 | } | |||
6465 | ||||
6466 | return true; | |||
6467 | }; | |||
6468 | ||||
6469 | return llvm::any_of(GuardingBranches, AllUsesGuardedByBranch); | |||
6470 | } | |||
6471 | ||||
6472 | /// Shifts return poison if shiftwidth is larger than the bitwidth. | |||
6473 | static bool shiftAmountKnownInRange(const Value *ShiftAmount) { | |||
6474 | auto *C = dyn_cast<Constant>(ShiftAmount); | |||
6475 | if (!C) | |||
6476 | return false; | |||
6477 | ||||
6478 | // Shifts return poison if shiftwidth is larger than the bitwidth. | |||
6479 | SmallVector<const Constant *, 4> ShiftAmounts; | |||
6480 | if (auto *FVTy = dyn_cast<FixedVectorType>(C->getType())) { | |||
6481 | unsigned NumElts = FVTy->getNumElements(); | |||
6482 | for (unsigned i = 0; i < NumElts; ++i) | |||
6483 | ShiftAmounts.push_back(C->getAggregateElement(i)); | |||
6484 | } else if (isa<ScalableVectorType>(C->getType())) | |||
6485 | return false; // Can't tell, just return false to be safe | |||
6486 | else | |||
6487 | ShiftAmounts.push_back(C); | |||
6488 | ||||
6489 | bool Safe = llvm::all_of(ShiftAmounts, [](const Constant *C) { | |||
6490 | auto *CI = dyn_cast_or_null<ConstantInt>(C); | |||
6491 | return CI && CI->getValue().ult(C->getType()->getIntegerBitWidth()); | |||
6492 | }); | |||
6493 | ||||
6494 | return Safe; | |||
6495 | } | |||
6496 | ||||
6497 | static bool canCreateUndefOrPoison(const Operator *Op, bool PoisonOnly, | |||
6498 | bool ConsiderFlagsAndMetadata) { | |||
6499 | ||||
6500 | if (ConsiderFlagsAndMetadata && Op->hasPoisonGeneratingFlagsOrMetadata()) | |||
6501 | return true; | |||
6502 | ||||
6503 | unsigned Opcode = Op->getOpcode(); | |||
6504 | ||||
6505 | // Check whether opcode is a poison/undef-generating operation | |||
6506 | switch (Opcode) { | |||
6507 | case Instruction::Shl: | |||
6508 | case Instruction::AShr: | |||
6509 | case Instruction::LShr: | |||
6510 | return !shiftAmountKnownInRange(Op->getOperand(1)); | |||
6511 | case Instruction::FPToSI: | |||
6512 | case Instruction::FPToUI: | |||
6513 | // fptosi/ui yields poison if the resulting value does not fit in the | |||
6514 | // destination type. | |||
6515 | return true; | |||
6516 | case Instruction::Call: | |||
6517 | if (auto *II = dyn_cast<IntrinsicInst>(Op)) { | |||
6518 | switch (II->getIntrinsicID()) { | |||
6519 | // TODO: Add more intrinsics. | |||
6520 | case Intrinsic::ctlz: | |||
6521 | case Intrinsic::cttz: | |||
6522 | case Intrinsic::abs: | |||
6523 | if (cast<ConstantInt>(II->getArgOperand(1))->isNullValue()) | |||
6524 | return false; | |||
6525 | break; | |||
6526 | case Intrinsic::ctpop: | |||
6527 | case Intrinsic::bswap: | |||
6528 | case Intrinsic::bitreverse: | |||
6529 | case Intrinsic::fshl: | |||
6530 | case Intrinsic::fshr: | |||
6531 | case Intrinsic::smax: | |||
6532 | case Intrinsic::smin: | |||
6533 | case Intrinsic::umax: | |||
6534 | case Intrinsic::umin: | |||
6535 | case Intrinsic::ptrmask: | |||
6536 | case Intrinsic::fptoui_sat: | |||
6537 | case Intrinsic::fptosi_sat: | |||
6538 | case Intrinsic::sadd_with_overflow: | |||
6539 | case Intrinsic::ssub_with_overflow: | |||
6540 | case Intrinsic::smul_with_overflow: | |||
6541 | case Intrinsic::uadd_with_overflow: | |||
6542 | case Intrinsic::usub_with_overflow: | |||
6543 | case Intrinsic::umul_with_overflow: | |||
6544 | case Intrinsic::sadd_sat: | |||
6545 | case Intrinsic::uadd_sat: | |||
6546 | case Intrinsic::ssub_sat: | |||
6547 | case Intrinsic::usub_sat: | |||
6548 | return false; | |||
6549 | case Intrinsic::sshl_sat: | |||
6550 | case Intrinsic::ushl_sat: | |||
6551 | return !shiftAmountKnownInRange(II->getArgOperand(1)); | |||
6552 | case Intrinsic::fma: | |||
6553 | case Intrinsic::fmuladd: | |||
6554 | case Intrinsic::sqrt: | |||
6555 | case Intrinsic::powi: | |||
6556 | case Intrinsic::sin: | |||
6557 | case Intrinsic::cos: | |||
6558 | case Intrinsic::pow: | |||
6559 | case Intrinsic::log: | |||
6560 | case Intrinsic::log10: | |||
6561 | case Intrinsic::log2: | |||
6562 | case Intrinsic::exp: | |||
6563 | case Intrinsic::exp2: | |||
6564 | case Intrinsic::fabs: | |||
6565 | case Intrinsic::copysign: | |||
6566 | case Intrinsic::floor: | |||
6567 | case Intrinsic::ceil: | |||
6568 | case Intrinsic::trunc: | |||
6569 | case Intrinsic::rint: | |||
6570 | case Intrinsic::nearbyint: | |||
6571 | case Intrinsic::round: | |||
6572 | case Intrinsic::roundeven: | |||
6573 | case Intrinsic::fptrunc_round: | |||
6574 | case Intrinsic::canonicalize: | |||
6575 | case Intrinsic::arithmetic_fence: | |||
6576 | case Intrinsic::minnum: | |||
6577 | case Intrinsic::maxnum: | |||
6578 | case Intrinsic::minimum: | |||
6579 | case Intrinsic::maximum: | |||
6580 | case Intrinsic::is_fpclass: | |||
6581 | return false; | |||
6582 | case Intrinsic::lround: | |||
6583 | case Intrinsic::llround: | |||
6584 | case Intrinsic::lrint: | |||
6585 | case Intrinsic::llrint: | |||
6586 | // If the value doesn't fit an unspecified value is returned (but this | |||
6587 | // is not poison). | |||
6588 | return false; | |||
6589 | } | |||
6590 | } | |||
6591 | [[fallthrough]]; | |||
6592 | case Instruction::CallBr: | |||
6593 | case Instruction::Invoke: { | |||
6594 | const auto *CB = cast<CallBase>(Op); | |||
6595 | return !CB->hasRetAttr(Attribute::NoUndef); | |||
6596 | } | |||
6597 | case Instruction::InsertElement: | |||
6598 | case Instruction::ExtractElement: { | |||
6599 | // If index exceeds the length of the vector, it returns poison | |||
6600 | auto *VTy = cast<VectorType>(Op->getOperand(0)->getType()); | |||
6601 | unsigned IdxOp = Op->getOpcode() == Instruction::InsertElement ? 2 : 1; | |||
6602 | auto *Idx = dyn_cast<ConstantInt>(Op->getOperand(IdxOp)); | |||
6603 | if (!Idx || Idx->getValue().uge(VTy->getElementCount().getKnownMinValue())) | |||
6604 | return true; | |||
6605 | return false; | |||
6606 | } | |||
6607 | case Instruction::ShuffleVector: { | |||
6608 | // shufflevector may return undef. | |||
6609 | if (PoisonOnly) | |||
6610 | return false; | |||
6611 | ArrayRef<int> Mask = isa<ConstantExpr>(Op) | |||
6612 | ? cast<ConstantExpr>(Op)->getShuffleMask() | |||
6613 | : cast<ShuffleVectorInst>(Op)->getShuffleMask(); | |||
6614 | return is_contained(Mask, PoisonMaskElem); | |||
6615 | } | |||
6616 | case Instruction::FNeg: | |||
6617 | case Instruction::PHI: | |||
6618 | case Instruction::Select: | |||
6619 | case Instruction::URem: | |||
6620 | case Instruction::SRem: | |||
6621 | case Instruction::ExtractValue: | |||
6622 | case Instruction::InsertValue: | |||
6623 | case Instruction::Freeze: | |||
6624 | case Instruction::ICmp: | |||
6625 | case Instruction::FCmp: | |||
6626 | case Instruction::FAdd: | |||
6627 | case Instruction::FSub: | |||
6628 | case Instruction::FMul: | |||
6629 | case Instruction::FDiv: | |||
6630 | case Instruction::FRem: | |||
6631 | return false; | |||
6632 | case Instruction::GetElementPtr: | |||
6633 | // inbounds is handled above | |||
6634 | // TODO: what about inrange on constexpr? | |||
6635 | return false; | |||
6636 | default: { | |||
6637 | const auto *CE = dyn_cast<ConstantExpr>(Op); | |||
6638 | if (isa<CastInst>(Op) || (CE && CE->isCast())) | |||
6639 | return false; | |||
6640 | else if (Instruction::isBinaryOp(Opcode)) | |||
6641 | return false; | |||
6642 | // Be conservative and return true. | |||
6643 | return true; | |||
6644 | } | |||
6645 | } | |||
6646 | } | |||
6647 | ||||
6648 | bool llvm::canCreateUndefOrPoison(const Operator *Op, | |||
6649 | bool ConsiderFlagsAndMetadata) { | |||
6650 | return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/false, | |||
6651 | ConsiderFlagsAndMetadata); | |||
6652 | } | |||
6653 | ||||
6654 | bool llvm::canCreatePoison(const Operator *Op, bool ConsiderFlagsAndMetadata) { | |||
6655 | return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/true, | |||
6656 | ConsiderFlagsAndMetadata); | |||
6657 | } | |||
6658 | ||||
6659 | static bool directlyImpliesPoison(const Value *ValAssumedPoison, | |||
6660 | const Value *V, unsigned Depth) { | |||
6661 | if (ValAssumedPoison == V) | |||
6662 | return true; | |||
6663 | ||||
6664 | const unsigned MaxDepth = 2; | |||
6665 | if (Depth >= MaxDepth) | |||
6666 | return false; | |||
6667 | ||||
6668 | if (const auto *I = dyn_cast<Instruction>(V)) { | |||
6669 | if (any_of(I->operands(), [=](const Use &Op) { | |||
6670 | return propagatesPoison(Op) && | |||
6671 | directlyImpliesPoison(ValAssumedPoison, Op, Depth + 1); | |||
6672 | })) | |||
6673 | return true; | |||
6674 | ||||
6675 | // V = extractvalue V0, idx | |||
6676 | // V2 = extractvalue V0, idx2 | |||
6677 | // V0's elements are all poison or not. (e.g., add_with_overflow) | |||
6678 | const WithOverflowInst *II; | |||
6679 | if (match(I, m_ExtractValue(m_WithOverflowInst(II))) && | |||
6680 | (match(ValAssumedPoison, m_ExtractValue(m_Specific(II))) || | |||
6681 | llvm::is_contained(II->args(), ValAssumedPoison))) | |||
6682 | return true; | |||
6683 | } | |||
6684 | return false; | |||
6685 | } | |||
6686 | ||||
6687 | static bool impliesPoison(const Value *ValAssumedPoison, const Value *V, | |||
6688 | unsigned Depth) { | |||
6689 | if (isGuaranteedNotToBePoison(ValAssumedPoison)) | |||
6690 | return true; | |||
6691 | ||||
6692 | if (directlyImpliesPoison(ValAssumedPoison, V, /* Depth */ 0)) | |||
6693 | return true; | |||
6694 | ||||
6695 | const unsigned MaxDepth = 2; | |||
6696 | if (Depth >= MaxDepth) | |||
6697 | return false; | |||
6698 | ||||
6699 | const auto *I = dyn_cast<Instruction>(ValAssumedPoison); | |||
6700 | if (I && !canCreatePoison(cast<Operator>(I))) { | |||
6701 | return all_of(I->operands(), [=](const Value *Op) { | |||
6702 | return impliesPoison(Op, V, Depth + 1); | |||
6703 | }); | |||
6704 | } | |||
6705 | return false; | |||
6706 | } | |||
6707 | ||||
6708 | bool llvm::impliesPoison(const Value *ValAssumedPoison, const Value *V) { | |||
6709 | return ::impliesPoison(ValAssumedPoison, V, /* Depth */ 0); | |||
6710 | } | |||
6711 | ||||
6712 | static bool programUndefinedIfUndefOrPoison(const Value *V, | |||
6713 | bool PoisonOnly); | |||
6714 | ||||
6715 | static bool isGuaranteedNotToBeUndefOrPoison(const Value *V, | |||
6716 | AssumptionCache *AC, | |||
6717 | const Instruction *CtxI, | |||
6718 | const DominatorTree *DT, | |||
6719 | unsigned Depth, bool PoisonOnly) { | |||
6720 | if (Depth >= MaxAnalysisRecursionDepth) | |||
6721 | return false; | |||
6722 | ||||
6723 | if (isa<MetadataAsValue>(V)) | |||
6724 | return false; | |||
6725 | ||||
6726 | if (const auto *A = dyn_cast<Argument>(V)) { | |||
6727 | if (A->hasAttribute(Attribute::NoUndef) || | |||
6728 | A->hasAttribute(Attribute::Dereferenceable) || | |||
6729 | A->hasAttribute(Attribute::DereferenceableOrNull)) | |||
6730 | return true; | |||
6731 | } | |||
6732 | ||||
6733 | if (auto *C = dyn_cast<Constant>(V)) { | |||
6734 | if (isa<UndefValue>(C)) | |||
6735 | return PoisonOnly && !isa<PoisonValue>(C); | |||
6736 | ||||
6737 | if (isa<ConstantInt>(C) || isa<GlobalVariable>(C) || isa<ConstantFP>(V) || | |||
6738 | isa<ConstantPointerNull>(C) || isa<Function>(C)) | |||
6739 | return true; | |||
6740 | ||||
6741 | if (C->getType()->isVectorTy() && !isa<ConstantExpr>(C)) | |||
6742 | return (PoisonOnly ? !C->containsPoisonElement() | |||
6743 | : !C->containsUndefOrPoisonElement()) && | |||
6744 | !C->containsConstantExpression(); | |||
6745 | } | |||
6746 | ||||
6747 | // Strip cast operations from a pointer value. | |||
6748 | // Note that stripPointerCastsSameRepresentation can strip off getelementptr | |||
6749 | // inbounds with zero offset. To guarantee that the result isn't poison, the | |||
6750 | // stripped pointer is checked as it has to be pointing into an allocated | |||
6751 | // object or be null `null` to ensure `inbounds` getelement pointers with a | |||
6752 | // zero offset could not produce poison. | |||
6753 | // It can strip off addrspacecast that do not change bit representation as | |||
6754 | // well. We believe that such addrspacecast is equivalent to no-op. | |||
6755 | auto *StrippedV = V->stripPointerCastsSameRepresentation(); | |||
6756 | if (isa<AllocaInst>(StrippedV) || isa<GlobalVariable>(StrippedV) || | |||
6757 | isa<Function>(StrippedV) || isa<ConstantPointerNull>(StrippedV)) | |||
6758 | return true; | |||
6759 | ||||
6760 | auto OpCheck = [&](const Value *V) { | |||
6761 | return isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth + 1, | |||
6762 | PoisonOnly); | |||
6763 | }; | |||
6764 | ||||
6765 | if (auto *Opr = dyn_cast<Operator>(V)) { | |||
6766 | // If the value is a freeze instruction, then it can never | |||
6767 | // be undef or poison. | |||
6768 | if (isa<FreezeInst>(V)) | |||
6769 | return true; | |||
6770 | ||||
6771 | if (const auto *CB = dyn_cast<CallBase>(V)) { | |||
6772 | if (CB->hasRetAttr(Attribute::NoUndef)) | |||
6773 | return true; | |||
6774 | } | |||
6775 | ||||
6776 | if (const auto *PN = dyn_cast<PHINode>(V)) { | |||
6777 | unsigned Num = PN->getNumIncomingValues(); | |||
6778 | bool IsWellDefined = true; | |||
6779 | for (unsigned i = 0; i < Num; ++i) { | |||
6780 | auto *TI = PN->getIncomingBlock(i)->getTerminator(); | |||
6781 | if (!isGuaranteedNotToBeUndefOrPoison(PN->getIncomingValue(i), AC, TI, | |||
6782 | DT, Depth + 1, PoisonOnly)) { | |||
6783 | IsWellDefined = false; | |||
6784 | break; | |||
6785 | } | |||
6786 | } | |||
6787 | if (IsWellDefined) | |||
6788 | return true; | |||
6789 | } else if (!canCreateUndefOrPoison(Opr) && all_of(Opr->operands(), OpCheck)) | |||
6790 | return true; | |||
6791 | } | |||
6792 | ||||
6793 | if (auto *I = dyn_cast<LoadInst>(V)) | |||
6794 | if (I->hasMetadata(LLVMContext::MD_noundef) || | |||
6795 | I->hasMetadata(LLVMContext::MD_dereferenceable) || | |||
6796 | I->hasMetadata(LLVMContext::MD_dereferenceable_or_null)) | |||
6797 | return true; | |||
6798 | ||||
6799 | if (programUndefinedIfUndefOrPoison(V, PoisonOnly)) | |||
6800 | return true; | |||
6801 | ||||
6802 | // CxtI may be null or a cloned instruction. | |||
6803 | if (!CtxI || !CtxI->getParent() || !DT) | |||
6804 | return false; | |||
6805 | ||||
6806 | auto *DNode = DT->getNode(CtxI->getParent()); | |||
6807 | if (!DNode) | |||
6808 | // Unreachable block | |||
6809 | return false; | |||
6810 | ||||
6811 | // If V is used as a branch condition before reaching CtxI, V cannot be | |||
6812 | // undef or poison. | |||
6813 | // br V, BB1, BB2 | |||
6814 | // BB1: | |||
6815 | // CtxI ; V cannot be undef or poison here | |||
6816 | auto *Dominator = DNode->getIDom(); | |||
6817 | while (Dominator) { | |||
6818 | auto *TI = Dominator->getBlock()->getTerminator(); | |||
6819 | ||||
6820 | Value *Cond = nullptr; | |||
6821 | if (auto BI = dyn_cast_or_null<BranchInst>(TI)) { | |||
6822 | if (BI->isConditional()) | |||
6823 | Cond = BI->getCondition(); | |||
6824 | } else if (auto SI = dyn_cast_or_null<SwitchInst>(TI)) { | |||
6825 | Cond = SI->getCondition(); | |||
6826 | } | |||
6827 | ||||
6828 | if (Cond) { | |||
6829 | if (Cond == V) | |||
6830 | return true; | |||
6831 | else if (PoisonOnly && isa<Operator>(Cond)) { | |||
6832 | // For poison, we can analyze further | |||
6833 | auto *Opr = cast<Operator>(Cond); | |||
6834 | if (any_of(Opr->operands(), | |||
6835 | [V](const Use &U) { return V == U && propagatesPoison(U); })) | |||
6836 | return true; | |||
6837 | } | |||
6838 | } | |||
6839 | ||||
6840 | Dominator = Dominator->getIDom(); | |||
6841 | } | |||
6842 | ||||
6843 | if (getKnowledgeValidInContext(V, {Attribute::NoUndef}, CtxI, DT, AC)) | |||
6844 | return true; | |||
6845 | ||||
6846 | return false; | |||
6847 | } | |||
6848 | ||||
6849 | bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V, AssumptionCache *AC, | |||
6850 | const Instruction *CtxI, | |||
6851 | const DominatorTree *DT, | |||
6852 | unsigned Depth) { | |||
6853 | return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, false); | |||
6854 | } | |||
6855 | ||||
6856 | bool llvm::isGuaranteedNotToBePoison(const Value *V, AssumptionCache *AC, | |||
6857 | const Instruction *CtxI, | |||
6858 | const DominatorTree *DT, unsigned Depth) { | |||
6859 | return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, true); | |||
6860 | } | |||
6861 | ||||
6862 | /// Return true if undefined behavior would provably be executed on the path to | |||
6863 | /// OnPathTo if Root produced a posion result. Note that this doesn't say | |||
6864 | /// anything about whether OnPathTo is actually executed or whether Root is | |||
6865 | /// actually poison. This can be used to assess whether a new use of Root can | |||
6866 | /// be added at a location which is control equivalent with OnPathTo (such as | |||
6867 | /// immediately before it) without introducing UB which didn't previously | |||
6868 | /// exist. Note that a false result conveys no information. | |||
6869 | bool llvm::mustExecuteUBIfPoisonOnPathTo(Instruction *Root, | |||
6870 | Instruction *OnPathTo, | |||
6871 | DominatorTree *DT) { | |||
6872 | // Basic approach is to assume Root is poison, propagate poison forward | |||
6873 | // through all users we can easily track, and then check whether any of those | |||
6874 | // users are provable UB and must execute before out exiting block might | |||
6875 | // exit. | |||
6876 | ||||
6877 | // The set of all recursive users we've visited (which are assumed to all be | |||
6878 | // poison because of said visit) | |||
6879 | SmallSet<const Value *, 16> KnownPoison; | |||
6880 | SmallVector<const Instruction*, 16> Worklist; | |||
6881 | Worklist.push_back(Root); | |||
6882 | while (!Worklist.empty()) { | |||
6883 | const Instruction *I = Worklist.pop_back_val(); | |||
6884 | ||||
6885 | // If we know this must trigger UB on a path leading our target. | |||
6886 | if (mustTriggerUB(I, KnownPoison) && DT->dominates(I, OnPathTo)) | |||
6887 | return true; | |||
6888 | ||||
6889 | // If we can't analyze propagation through this instruction, just skip it | |||
6890 | // and transitive users. Safe as false is a conservative result. | |||
6891 | if (I != Root && !any_of(I->operands(), [&KnownPoison](const Use &U) { | |||
6892 | return KnownPoison.contains(U) && propagatesPoison(U); | |||
6893 | })) | |||
6894 | continue; | |||
6895 | ||||
6896 | if (KnownPoison.insert(I).second) | |||
6897 | for (const User *User : I->users()) | |||
6898 | Worklist.push_back(cast<Instruction>(User)); | |||
6899 | } | |||
6900 | ||||
6901 | // Might be non-UB, or might have a path we couldn't prove must execute on | |||
6902 | // way to exiting bb. | |||
6903 | return false; | |||
6904 | } | |||
6905 | ||||
6906 | OverflowResult llvm::computeOverflowForSignedAdd(const AddOperator *Add, | |||
6907 | const DataLayout &DL, | |||
6908 | AssumptionCache *AC, | |||
6909 | const Instruction *CxtI, | |||
6910 | const DominatorTree *DT) { | |||
6911 | return ::computeOverflowForSignedAdd(Add->getOperand(0), Add->getOperand(1), | |||
6912 | Add, DL, AC, CxtI, DT); | |||
6913 | } | |||
6914 | ||||
6915 | OverflowResult llvm::computeOverflowForSignedAdd(const Value *LHS, | |||
6916 | const Value *RHS, | |||
6917 | const DataLayout &DL, | |||
6918 | AssumptionCache *AC, | |||
6919 | const Instruction *CxtI, | |||
6920 | const DominatorTree *DT) { | |||
6921 | return ::computeOverflowForSignedAdd(LHS, RHS, nullptr, DL, AC, CxtI, DT); | |||
6922 | } | |||
6923 | ||||
6924 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const Instruction *I) { | |||
6925 | // Note: An atomic operation isn't guaranteed to return in a reasonable amount | |||
6926 | // of time because it's possible for another thread to interfere with it for an | |||
6927 | // arbitrary length of time, but programs aren't allowed to rely on that. | |||
6928 | ||||
6929 | // If there is no successor, then execution can't transfer to it. | |||
6930 | if (isa<ReturnInst>(I)) | |||
6931 | return false; | |||
6932 | if (isa<UnreachableInst>(I)) | |||
6933 | return false; | |||
6934 | ||||
6935 | // Note: Do not add new checks here; instead, change Instruction::mayThrow or | |||
6936 | // Instruction::willReturn. | |||
6937 | // | |||
6938 | // FIXME: Move this check into Instruction::willReturn. | |||
6939 | if (isa<CatchPadInst>(I)) { | |||
6940 | switch (classifyEHPersonality(I->getFunction()->getPersonalityFn())) { | |||
6941 | default: | |||
6942 | // A catchpad may invoke exception object constructors and such, which | |||
6943 | // in some languages can be arbitrary code, so be conservative by default. | |||
6944 | return false; | |||
6945 | case EHPersonality::CoreCLR: | |||
6946 | // For CoreCLR, it just involves a type test. | |||
6947 | return true; | |||
6948 | } | |||
6949 | } | |||
6950 | ||||
6951 | // An instruction that returns without throwing must transfer control flow | |||
6952 | // to a successor. | |||
6953 | return !I->mayThrow() && I->willReturn(); | |||
6954 | } | |||
6955 | ||||
6956 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB) { | |||
6957 | // TODO: This is slightly conservative for invoke instruction since exiting | |||
6958 | // via an exception *is* normal control for them. | |||
6959 | for (const Instruction &I : *BB) | |||
6960 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
6961 | return false; | |||
6962 | return true; | |||
6963 | } | |||
6964 | ||||
6965 | bool llvm::isGuaranteedToTransferExecutionToSuccessor( | |||
6966 | BasicBlock::const_iterator Begin, BasicBlock::const_iterator End, | |||
6967 | unsigned ScanLimit) { | |||
6968 | return isGuaranteedToTransferExecutionToSuccessor(make_range(Begin, End), | |||
6969 | ScanLimit); | |||
6970 | } | |||
6971 | ||||
6972 | bool llvm::isGuaranteedToTransferExecutionToSuccessor( | |||
6973 | iterator_range<BasicBlock::const_iterator> Range, unsigned ScanLimit) { | |||
6974 | assert(ScanLimit && "scan limit must be non-zero")(static_cast <bool> (ScanLimit && "scan limit must be non-zero" ) ? void (0) : __assert_fail ("ScanLimit && \"scan limit must be non-zero\"" , "llvm/lib/Analysis/ValueTracking.cpp", 6974, __extension__ __PRETTY_FUNCTION__ )); | |||
6975 | for (const Instruction &I : Range) { | |||
6976 | if (isa<DbgInfoIntrinsic>(I)) | |||
6977 | continue; | |||
6978 | if (--ScanLimit == 0) | |||
6979 | return false; | |||
6980 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
6981 | return false; | |||
6982 | } | |||
6983 | return true; | |||
6984 | } | |||
6985 | ||||
6986 | bool llvm::isGuaranteedToExecuteForEveryIteration(const Instruction *I, | |||
6987 | const Loop *L) { | |||
6988 | // The loop header is guaranteed to be executed for every iteration. | |||
6989 | // | |||
6990 | // FIXME: Relax this constraint to cover all basic blocks that are | |||
6991 | // guaranteed to be executed at every iteration. | |||
6992 | if (I->getParent() != L->getHeader()) return false; | |||
6993 | ||||
6994 | for (const Instruction &LI : *L->getHeader()) { | |||
6995 | if (&LI == I) return true; | |||
6996 | if (!isGuaranteedToTransferExecutionToSuccessor(&LI)) return false; | |||
6997 | } | |||
6998 | llvm_unreachable("Instruction not contained in its own parent basic block.")::llvm::llvm_unreachable_internal("Instruction not contained in its own parent basic block." , "llvm/lib/Analysis/ValueTracking.cpp", 6998); | |||
6999 | } | |||
7000 | ||||
7001 | bool llvm::propagatesPoison(const Use &PoisonOp) { | |||
7002 | const Operator *I = cast<Operator>(PoisonOp.getUser()); | |||
7003 | switch (I->getOpcode()) { | |||
7004 | case Instruction::Freeze: | |||
7005 | case Instruction::PHI: | |||
7006 | case Instruction::Invoke: | |||
7007 | return false; | |||
7008 | case Instruction::Select: | |||
7009 | return PoisonOp.getOperandNo() == 0; | |||
7010 | case Instruction::Call: | |||
7011 | if (auto *II = dyn_cast<IntrinsicInst>(I)) { | |||
7012 | switch (II->getIntrinsicID()) { | |||
7013 | // TODO: Add more intrinsics. | |||
7014 | case Intrinsic::sadd_with_overflow: | |||
7015 | case Intrinsic::ssub_with_overflow: | |||
7016 | case Intrinsic::smul_with_overflow: | |||
7017 | case Intrinsic::uadd_with_overflow: | |||
7018 | case Intrinsic::usub_with_overflow: | |||
7019 | case Intrinsic::umul_with_overflow: | |||
7020 | // If an input is a vector containing a poison element, the | |||
7021 | // two output vectors (calculated results, overflow bits)' | |||
7022 | // corresponding lanes are poison. | |||
7023 | return true; | |||
7024 | case Intrinsic::ctpop: | |||
7025 | return true; | |||
7026 | } | |||
7027 | } | |||
7028 | return false; | |||
7029 | case Instruction::ICmp: | |||
7030 | case Instruction::FCmp: | |||
7031 | case Instruction::GetElementPtr: | |||
7032 | return true; | |||
7033 | default: | |||
7034 | if (isa<BinaryOperator>(I) || isa<UnaryOperator>(I) || isa<CastInst>(I)) | |||
7035 | return true; | |||
7036 | ||||
7037 | // Be conservative and return false. | |||
7038 | return false; | |||
7039 | } | |||
7040 | } | |||
7041 | ||||
7042 | void llvm::getGuaranteedWellDefinedOps( | |||
7043 | const Instruction *I, SmallVectorImpl<const Value *> &Operands) { | |||
7044 | switch (I->getOpcode()) { | |||
7045 | case Instruction::Store: | |||
7046 | Operands.push_back(cast<StoreInst>(I)->getPointerOperand()); | |||
7047 | break; | |||
7048 | ||||
7049 | case Instruction::Load: | |||
7050 | Operands.push_back(cast<LoadInst>(I)->getPointerOperand()); | |||
7051 | break; | |||
7052 | ||||
7053 | // Since dereferenceable attribute imply noundef, atomic operations | |||
7054 | // also implicitly have noundef pointers too | |||
7055 | case Instruction::AtomicCmpXchg: | |||
7056 | Operands.push_back(cast<AtomicCmpXchgInst>(I)->getPointerOperand()); | |||
7057 | break; | |||
7058 | ||||
7059 | case Instruction::AtomicRMW: | |||
7060 | Operands.push_back(cast<AtomicRMWInst>(I)->getPointerOperand()); | |||
7061 | break; | |||
7062 | ||||
7063 | case Instruction::Call: | |||
7064 | case Instruction::Invoke: { | |||
7065 | const CallBase *CB = cast<CallBase>(I); | |||
7066 | if (CB->isIndirectCall()) | |||
7067 | Operands.push_back(CB->getCalledOperand()); | |||
7068 | for (unsigned i = 0; i < CB->arg_size(); ++i) { | |||
7069 | if (CB->paramHasAttr(i, Attribute::NoUndef) || | |||
7070 | CB->paramHasAttr(i, Attribute::Dereferenceable)) | |||
7071 | Operands.push_back(CB->getArgOperand(i)); | |||
7072 | } | |||
7073 | break; | |||
7074 | } | |||
7075 | case Instruction::Ret: | |||
7076 | if (I->getFunction()->hasRetAttribute(Attribute::NoUndef)) | |||
7077 | Operands.push_back(I->getOperand(0)); | |||
7078 | break; | |||
7079 | case Instruction::Switch: | |||
7080 | Operands.push_back(cast<SwitchInst>(I)->getCondition()); | |||
7081 | break; | |||
7082 | case Instruction::Br: { | |||
7083 | auto *BR = cast<BranchInst>(I); | |||
7084 | if (BR->isConditional()) | |||
7085 | Operands.push_back(BR->getCondition()); | |||
7086 | break; | |||
7087 | } | |||
7088 | default: | |||
7089 | break; | |||
7090 | } | |||
7091 | } | |||
7092 | ||||
7093 | void llvm::getGuaranteedNonPoisonOps(const Instruction *I, | |||
7094 | SmallVectorImpl<const Value *> &Operands) { | |||
7095 | getGuaranteedWellDefinedOps(I, Operands); | |||
7096 | switch (I->getOpcode()) { | |||
7097 | // Divisors of these operations are allowed to be partially undef. | |||
7098 | case Instruction::UDiv: | |||
7099 | case Instruction::SDiv: | |||
7100 | case Instruction::URem: | |||
7101 | case Instruction::SRem: | |||
7102 | Operands.push_back(I->getOperand(1)); | |||
7103 | break; | |||
7104 | default: | |||
7105 | break; | |||
7106 | } | |||
7107 | } | |||
7108 | ||||
7109 | bool llvm::mustTriggerUB(const Instruction *I, | |||
7110 | const SmallPtrSetImpl<const Value *> &KnownPoison) { | |||
7111 | SmallVector<const Value *, 4> NonPoisonOps; | |||
7112 | getGuaranteedNonPoisonOps(I, NonPoisonOps); | |||
7113 | ||||
7114 | for (const auto *V : NonPoisonOps) | |||
7115 | if (KnownPoison.count(V)) | |||
7116 | return true; | |||
7117 | ||||
7118 | return false; | |||
7119 | } | |||
7120 | ||||
7121 | static bool programUndefinedIfUndefOrPoison(const Value *V, | |||
7122 | bool PoisonOnly) { | |||
7123 | // We currently only look for uses of values within the same basic | |||
7124 | // block, as that makes it easier to guarantee that the uses will be | |||
7125 | // executed given that Inst is executed. | |||
7126 | // | |||
7127 | // FIXME: Expand this to consider uses beyond the same basic block. To do | |||
7128 | // this, look out for the distinction between post-dominance and strong | |||
7129 | // post-dominance. | |||
7130 | const BasicBlock *BB = nullptr; | |||
7131 | BasicBlock::const_iterator Begin; | |||
7132 | if (const auto *Inst = dyn_cast<Instruction>(V)) { | |||
7133 | BB = Inst->getParent(); | |||
7134 | Begin = Inst->getIterator(); | |||
7135 | Begin++; | |||
7136 | } else if (const auto *Arg = dyn_cast<Argument>(V)) { | |||
7137 | BB = &Arg->getParent()->getEntryBlock(); | |||
7138 | Begin = BB->begin(); | |||
7139 | } else { | |||
7140 | return false; | |||
7141 | } | |||
7142 | ||||
7143 | // Limit number of instructions we look at, to avoid scanning through large | |||
7144 | // blocks. The current limit is chosen arbitrarily. | |||
7145 | unsigned ScanLimit = 32; | |||
7146 | BasicBlock::const_iterator End = BB->end(); | |||
7147 | ||||
7148 | if (!PoisonOnly) { | |||
7149 | // Since undef does not propagate eagerly, be conservative & just check | |||
7150 | // whether a value is directly passed to an instruction that must take | |||
7151 | // well-defined operands. | |||
7152 | ||||
7153 | for (const auto &I : make_range(Begin, End)) { | |||
7154 | if (isa<DbgInfoIntrinsic>(I)) | |||
7155 | continue; | |||
7156 | if (--ScanLimit == 0) | |||
7157 | break; | |||
7158 | ||||
7159 | SmallVector<const Value *, 4> WellDefinedOps; | |||
7160 | getGuaranteedWellDefinedOps(&I, WellDefinedOps); | |||
7161 | if (is_contained(WellDefinedOps, V)) | |||
7162 | return true; | |||
7163 | ||||
7164 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
7165 | break; | |||
7166 | } | |||
7167 | return false; | |||
7168 | } | |||
7169 | ||||
7170 | // Set of instructions that we have proved will yield poison if Inst | |||
7171 | // does. | |||
7172 | SmallSet<const Value *, 16> YieldsPoison; | |||
7173 | SmallSet<const BasicBlock *, 4> Visited; | |||
7174 | ||||
7175 | YieldsPoison.insert(V); | |||
7176 | Visited.insert(BB); | |||
7177 | ||||
7178 | while (true) { | |||
7179 | for (const auto &I : make_range(Begin, End)) { | |||
7180 | if (isa<DbgInfoIntrinsic>(I)) | |||
7181 | continue; | |||
7182 | if (--ScanLimit == 0) | |||
7183 | return false; | |||
7184 | if (mustTriggerUB(&I, YieldsPoison)) | |||
7185 | return true; | |||
7186 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
7187 | return false; | |||
7188 | ||||
7189 | // If an operand is poison and propagates it, mark I as yielding poison. | |||
7190 | for (const Use &Op : I.operands()) { | |||
7191 | if (YieldsPoison.count(Op) && propagatesPoison(Op)) { | |||
7192 | YieldsPoison.insert(&I); | |||
7193 | break; | |||
7194 | } | |||
7195 | } | |||
7196 | ||||
7197 | // Special handling for select, which returns poison if its operand 0 is | |||
7198 | // poison (handled in the loop above) *or* if both its true/false operands | |||
7199 | // are poison (handled here). | |||
7200 | if (I.getOpcode() == Instruction::Select && | |||
7201 | YieldsPoison.count(I.getOperand(1)) && | |||
7202 | YieldsPoison.count(I.getOperand(2))) { | |||
7203 | YieldsPoison.insert(&I); | |||
7204 | } | |||
7205 | } | |||
7206 | ||||
7207 | BB = BB->getSingleSuccessor(); | |||
7208 | if (!BB || !Visited.insert(BB).second) | |||
7209 | break; | |||
7210 | ||||
7211 | Begin = BB->getFirstNonPHI()->getIterator(); | |||
7212 | End = BB->end(); | |||
7213 | } | |||
7214 | return false; | |||
7215 | } | |||
7216 | ||||
7217 | bool llvm::programUndefinedIfUndefOrPoison(const Instruction *Inst) { | |||
7218 | return ::programUndefinedIfUndefOrPoison(Inst, false); | |||
7219 | } | |||
7220 | ||||
7221 | bool llvm::programUndefinedIfPoison(const Instruction *Inst) { | |||
7222 | return ::programUndefinedIfUndefOrPoison(Inst, true); | |||
7223 | } | |||
7224 | ||||
7225 | static bool isKnownNonNaN(const Value *V, FastMathFlags FMF) { | |||
7226 | if (FMF.noNaNs()) | |||
7227 | return true; | |||
7228 | ||||
7229 | if (auto *C = dyn_cast<ConstantFP>(V)) | |||
7230 | return !C->isNaN(); | |||
7231 | ||||
7232 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { | |||
7233 | if (!C->getElementType()->isFloatingPointTy()) | |||
7234 | return false; | |||
7235 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { | |||
7236 | if (C->getElementAsAPFloat(I).isNaN()) | |||
7237 | return false; | |||
7238 | } | |||
7239 | return true; | |||
7240 | } | |||
7241 | ||||
7242 | if (isa<ConstantAggregateZero>(V)) | |||
7243 | return true; | |||
7244 | ||||
7245 | return false; | |||
7246 | } | |||
7247 | ||||
7248 | static bool isKnownNonZero(const Value *V) { | |||
7249 | if (auto *C = dyn_cast<ConstantFP>(V)) | |||
7250 | return !C->isZero(); | |||
7251 | ||||
7252 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { | |||
7253 | if (!C->getElementType()->isFloatingPointTy()) | |||
7254 | return false; | |||
7255 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { | |||
7256 | if (C->getElementAsAPFloat(I).isZero()) | |||
7257 | return false; | |||
7258 | } | |||
7259 | return true; | |||
7260 | } | |||
7261 | ||||
7262 | return false; | |||
7263 | } | |||
7264 | ||||
7265 | /// Match clamp pattern for float types without care about NaNs or signed zeros. | |||
7266 | /// Given non-min/max outer cmp/select from the clamp pattern this | |||
7267 | /// function recognizes if it can be substitued by a "canonical" min/max | |||
7268 | /// pattern. | |||
7269 | static SelectPatternResult matchFastFloatClamp(CmpInst::Predicate Pred, | |||
7270 | Value *CmpLHS, Value *CmpRHS, | |||
7271 | Value *TrueVal, Value *FalseVal, | |||
7272 | Value *&LHS, Value *&RHS) { | |||
7273 | // Try to match | |||
7274 | // X < C1 ? C1 : Min(X, C2) --> Max(C1, Min(X, C2)) | |||
7275 | // X > C1 ? C1 : Max(X, C2) --> Min(C1, Max(X, C2)) | |||
7276 | // and return description of the outer Max/Min. | |||
7277 | ||||
7278 | // First, check if select has inverse order: | |||
7279 | if (CmpRHS == FalseVal) { | |||
7280 | std::swap(TrueVal, FalseVal); | |||
7281 | Pred = CmpInst::getInversePredicate(Pred); | |||
7282 | } | |||
7283 | ||||
7284 | // Assume success now. If there's no match, callers should not use these anyway. | |||
7285 | LHS = TrueVal; | |||
7286 | RHS = FalseVal; | |||
7287 | ||||
7288 | const APFloat *FC1; | |||
7289 | if (CmpRHS != TrueVal || !match(CmpRHS, m_APFloat(FC1)) || !FC1->isFinite()) | |||
7290 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7291 | ||||
7292 | const APFloat *FC2; | |||
7293 | switch (Pred) { | |||
7294 | case CmpInst::FCMP_OLT: | |||
7295 | case CmpInst::FCMP_OLE: | |||
7296 | case CmpInst::FCMP_ULT: | |||
7297 | case CmpInst::FCMP_ULE: | |||
7298 | if (match(FalseVal, | |||
7299 | m_CombineOr(m_OrdFMin(m_Specific(CmpLHS), m_APFloat(FC2)), | |||
7300 | m_UnordFMin(m_Specific(CmpLHS), m_APFloat(FC2)))) && | |||
7301 | *FC1 < *FC2) | |||
7302 | return {SPF_FMAXNUM, SPNB_RETURNS_ANY, false}; | |||
7303 | break; | |||
7304 | case CmpInst::FCMP_OGT: | |||
7305 | case CmpInst::FCMP_OGE: | |||
7306 | case CmpInst::FCMP_UGT: | |||
7307 | case CmpInst::FCMP_UGE: | |||
7308 | if (match(FalseVal, | |||
7309 | m_CombineOr(m_OrdFMax(m_Specific(CmpLHS), m_APFloat(FC2)), | |||
7310 | m_UnordFMax(m_Specific(CmpLHS), m_APFloat(FC2)))) && | |||
7311 | *FC1 > *FC2) | |||
7312 | return {SPF_FMINNUM, SPNB_RETURNS_ANY, false}; | |||
7313 | break; | |||
7314 | default: | |||
7315 | break; | |||
7316 | } | |||
7317 | ||||
7318 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7319 | } | |||
7320 | ||||
7321 | /// Recognize variations of: | |||
7322 | /// CLAMP(v,l,h) ==> ((v) < (l) ? (l) : ((v) > (h) ? (h) : (v))) | |||
7323 | static SelectPatternResult matchClamp(CmpInst::Predicate Pred, | |||
7324 | Value *CmpLHS, Value *CmpRHS, | |||
7325 | Value *TrueVal, Value *FalseVal) { | |||
7326 | // Swap the select operands and predicate to match the patterns below. | |||
7327 | if (CmpRHS != TrueVal) { | |||
7328 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
7329 | std::swap(TrueVal, FalseVal); | |||
7330 | } | |||
7331 | const APInt *C1; | |||
7332 | if (CmpRHS == TrueVal && match(CmpRHS, m_APInt(C1))) { | |||
7333 | const APInt *C2; | |||
7334 | // (X <s C1) ? C1 : SMIN(X, C2) ==> SMAX(SMIN(X, C2), C1) | |||
7335 | if (match(FalseVal, m_SMin(m_Specific(CmpLHS), m_APInt(C2))) && | |||
7336 | C1->slt(*C2) && Pred == CmpInst::ICMP_SLT) | |||
7337 | return {SPF_SMAX, SPNB_NA, false}; | |||
7338 | ||||
7339 | // (X >s C1) ? C1 : SMAX(X, C2) ==> SMIN(SMAX(X, C2), C1) | |||
7340 | if (match(FalseVal, m_SMax(m_Specific(CmpLHS), m_APInt(C2))) && | |||
7341 | C1->sgt(*C2) && Pred == CmpInst::ICMP_SGT) | |||
7342 | return {SPF_SMIN, SPNB_NA, false}; | |||
7343 | ||||
7344 | // (X <u C1) ? C1 : UMIN(X, C2) ==> UMAX(UMIN(X, C2), C1) | |||
7345 | if (match(FalseVal, m_UMin(m_Specific(CmpLHS), m_APInt(C2))) && | |||
7346 | C1->ult(*C2) && Pred == CmpInst::ICMP_ULT) | |||
7347 | return {SPF_UMAX, SPNB_NA, false}; | |||
7348 | ||||
7349 | // (X >u C1) ? C1 : UMAX(X, C2) ==> UMIN(UMAX(X, C2), C1) | |||
7350 | if (match(FalseVal, m_UMax(m_Specific(CmpLHS), m_APInt(C2))) && | |||
7351 | C1->ugt(*C2) && Pred == CmpInst::ICMP_UGT) | |||
7352 | return {SPF_UMIN, SPNB_NA, false}; | |||
7353 | } | |||
7354 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7355 | } | |||
7356 | ||||
7357 | /// Recognize variations of: | |||
7358 | /// a < c ? min(a,b) : min(b,c) ==> min(min(a,b),min(b,c)) | |||
7359 | static SelectPatternResult matchMinMaxOfMinMax(CmpInst::Predicate Pred, | |||
7360 | Value *CmpLHS, Value *CmpRHS, | |||
7361 | Value *TVal, Value *FVal, | |||
7362 | unsigned Depth) { | |||
7363 | // TODO: Allow FP min/max with nnan/nsz. | |||
7364 | assert(CmpInst::isIntPredicate(Pred) && "Expected integer comparison")(static_cast <bool> (CmpInst::isIntPredicate(Pred) && "Expected integer comparison") ? void (0) : __assert_fail ("CmpInst::isIntPredicate(Pred) && \"Expected integer comparison\"" , "llvm/lib/Analysis/ValueTracking.cpp", 7364, __extension__ __PRETTY_FUNCTION__ )); | |||
7365 | ||||
7366 | Value *A = nullptr, *B = nullptr; | |||
7367 | SelectPatternResult L = matchSelectPattern(TVal, A, B, nullptr, Depth + 1); | |||
7368 | if (!SelectPatternResult::isMinOrMax(L.Flavor)) | |||
7369 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7370 | ||||
7371 | Value *C = nullptr, *D = nullptr; | |||
7372 | SelectPatternResult R = matchSelectPattern(FVal, C, D, nullptr, Depth + 1); | |||
7373 | if (L.Flavor != R.Flavor) | |||
7374 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7375 | ||||
7376 | // We have something like: x Pred y ? min(a, b) : min(c, d). | |||
7377 | // Try to match the compare to the min/max operations of the select operands. | |||
7378 | // First, make sure we have the right compare predicate. | |||
7379 | switch (L.Flavor) { | |||
7380 | case SPF_SMIN: | |||
7381 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) { | |||
7382 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
7383 | std::swap(CmpLHS, CmpRHS); | |||
7384 | } | |||
7385 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) | |||
7386 | break; | |||
7387 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7388 | case SPF_SMAX: | |||
7389 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) { | |||
7390 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
7391 | std::swap(CmpLHS, CmpRHS); | |||
7392 | } | |||
7393 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) | |||
7394 | break; | |||
7395 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7396 | case SPF_UMIN: | |||
7397 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) { | |||
7398 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
7399 | std::swap(CmpLHS, CmpRHS); | |||
7400 | } | |||
7401 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) | |||
7402 | break; | |||
7403 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7404 | case SPF_UMAX: | |||
7405 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { | |||
7406 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
7407 | std::swap(CmpLHS, CmpRHS); | |||
7408 | } | |||
7409 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) | |||
7410 | break; | |||
7411 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7412 | default: | |||
7413 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7414 | } | |||
7415 | ||||
7416 | // If there is a common operand in the already matched min/max and the other | |||
7417 | // min/max operands match the compare operands (either directly or inverted), | |||
7418 | // then this is min/max of the same flavor. | |||
7419 | ||||
7420 | // a pred c ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) | |||
7421 | // ~c pred ~a ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) | |||
7422 | if (D == B) { | |||
7423 | if ((CmpLHS == A && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && | |||
7424 | match(A, m_Not(m_Specific(CmpRHS))))) | |||
7425 | return {L.Flavor, SPNB_NA, false}; | |||
7426 | } | |||
7427 | // a pred d ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) | |||
7428 | // ~d pred ~a ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) | |||
7429 | if (C == B) { | |||
7430 | if ((CmpLHS == A && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && | |||
7431 | match(A, m_Not(m_Specific(CmpRHS))))) | |||
7432 | return {L.Flavor, SPNB_NA, false}; | |||
7433 | } | |||
7434 | // b pred c ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) | |||
7435 | // ~c pred ~b ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) | |||
7436 | if (D == A) { | |||
7437 | if ((CmpLHS == B && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && | |||
7438 | match(B, m_Not(m_Specific(CmpRHS))))) | |||
7439 | return {L.Flavor, SPNB_NA, false}; | |||
7440 | } | |||
7441 | // b pred d ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) | |||
7442 | // ~d pred ~b ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) | |||
7443 | if (C == A) { | |||
7444 | if ((CmpLHS == B && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && | |||
7445 | match(B, m_Not(m_Specific(CmpRHS))))) | |||
7446 | return {L.Flavor, SPNB_NA, false}; | |||
7447 | } | |||
7448 | ||||
7449 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7450 | } | |||
7451 | ||||
7452 | /// If the input value is the result of a 'not' op, constant integer, or vector | |||
7453 | /// splat of a constant integer, return the bitwise-not source value. | |||
7454 | /// TODO: This could be extended to handle non-splat vector integer constants. | |||
7455 | static Value *getNotValue(Value *V) { | |||
7456 | Value *NotV; | |||
7457 | if (match(V, m_Not(m_Value(NotV)))) | |||
7458 | return NotV; | |||
7459 | ||||
7460 | const APInt *C; | |||
7461 | if (match(V, m_APInt(C))) | |||
7462 | return ConstantInt::get(V->getType(), ~(*C)); | |||
7463 | ||||
7464 | return nullptr; | |||
7465 | } | |||
7466 | ||||
7467 | /// Match non-obvious integer minimum and maximum sequences. | |||
7468 | static SelectPatternResult matchMinMax(CmpInst::Predicate Pred, | |||
7469 | Value *CmpLHS, Value *CmpRHS, | |||
7470 | Value *TrueVal, Value *FalseVal, | |||
7471 | Value *&LHS, Value *&RHS, | |||
7472 | unsigned Depth) { | |||
7473 | // Assume success. If there's no match, callers should not use these anyway. | |||
7474 | LHS = TrueVal; | |||
7475 | RHS = FalseVal; | |||
7476 | ||||
7477 | SelectPatternResult SPR = matchClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal); | |||
7478 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) | |||
7479 | return SPR; | |||
7480 | ||||
7481 | SPR = matchMinMaxOfMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, Depth); | |||
7482 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) | |||
7483 | return SPR; | |||
7484 | ||||
7485 | // Look through 'not' ops to find disguised min/max. | |||
7486 | // (X > Y) ? ~X : ~Y ==> (~X < ~Y) ? ~X : ~Y ==> MIN(~X, ~Y) | |||
7487 | // (X < Y) ? ~X : ~Y ==> (~X > ~Y) ? ~X : ~Y ==> MAX(~X, ~Y) | |||
7488 | if (CmpLHS == getNotValue(TrueVal) && CmpRHS == getNotValue(FalseVal)) { | |||
7489 | switch (Pred) { | |||
7490 | case CmpInst::ICMP_SGT: return {SPF_SMIN, SPNB_NA, false}; | |||
7491 | case CmpInst::ICMP_SLT: return {SPF_SMAX, SPNB_NA, false}; | |||
7492 | case CmpInst::ICMP_UGT: return {SPF_UMIN, SPNB_NA, false}; | |||
7493 | case CmpInst::ICMP_ULT: return {SPF_UMAX, SPNB_NA, false}; | |||
7494 | default: break; | |||
7495 | } | |||
7496 | } | |||
7497 | ||||
7498 | // (X > Y) ? ~Y : ~X ==> (~X < ~Y) ? ~Y : ~X ==> MAX(~Y, ~X) | |||
7499 | // (X < Y) ? ~Y : ~X ==> (~X > ~Y) ? ~Y : ~X ==> MIN(~Y, ~X) | |||
7500 | if (CmpLHS == getNotValue(FalseVal) && CmpRHS == getNotValue(TrueVal)) { | |||
7501 | switch (Pred) { | |||
7502 | case CmpInst::ICMP_SGT: return {SPF_SMAX, SPNB_NA, false}; | |||
7503 | case CmpInst::ICMP_SLT: return {SPF_SMIN, SPNB_NA, false}; | |||
7504 | case CmpInst::ICMP_UGT: return {SPF_UMAX, SPNB_NA, false}; | |||
7505 | case CmpInst::ICMP_ULT: return {SPF_UMIN, SPNB_NA, false}; | |||
7506 | default: break; | |||
7507 | } | |||
7508 | } | |||
7509 | ||||
7510 | if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT) | |||
7511 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7512 | ||||
7513 | const APInt *C1; | |||
7514 | if (!match(CmpRHS, m_APInt(C1))) | |||
7515 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7516 | ||||
7517 | // An unsigned min/max can be written with a signed compare. | |||
7518 | const APInt *C2; | |||
7519 | if ((CmpLHS == TrueVal && match(FalseVal, m_APInt(C2))) || | |||
7520 | (CmpLHS == FalseVal && match(TrueVal, m_APInt(C2)))) { | |||
7521 | // Is the sign bit set? | |||
7522 | // (X <s 0) ? X : MAXVAL ==> (X >u MAXVAL) ? X : MAXVAL ==> UMAX | |||
7523 | // (X <s 0) ? MAXVAL : X ==> (X >u MAXVAL) ? MAXVAL : X ==> UMIN | |||
7524 | if (Pred == CmpInst::ICMP_SLT && C1->isZero() && C2->isMaxSignedValue()) | |||
7525 | return {CmpLHS == TrueVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; | |||
7526 | ||||
7527 | // Is the sign bit clear? | |||
7528 | // (X >s -1) ? MINVAL : X ==> (X <u MINVAL) ? MINVAL : X ==> UMAX | |||
7529 | // (X >s -1) ? X : MINVAL ==> (X <u MINVAL) ? X : MINVAL ==> UMIN | |||
7530 | if (Pred == CmpInst::ICMP_SGT && C1->isAllOnes() && C2->isMinSignedValue()) | |||
7531 | return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; | |||
7532 | } | |||
7533 | ||||
7534 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7535 | } | |||
7536 | ||||
7537 | bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW) { | |||
7538 | assert(X && Y && "Invalid operand")(static_cast <bool> (X && Y && "Invalid operand" ) ? void (0) : __assert_fail ("X && Y && \"Invalid operand\"" , "llvm/lib/Analysis/ValueTracking.cpp", 7538, __extension__ __PRETTY_FUNCTION__ )); | |||
7539 | ||||
7540 | // X = sub (0, Y) || X = sub nsw (0, Y) | |||
7541 | if ((!NeedNSW && match(X, m_Sub(m_ZeroInt(), m_Specific(Y)))) || | |||
7542 | (NeedNSW && match(X, m_NSWSub(m_ZeroInt(), m_Specific(Y))))) | |||
7543 | return true; | |||
7544 | ||||
7545 | // Y = sub (0, X) || Y = sub nsw (0, X) | |||
7546 | if ((!NeedNSW && match(Y, m_Sub(m_ZeroInt(), m_Specific(X)))) || | |||
7547 | (NeedNSW && match(Y, m_NSWSub(m_ZeroInt(), m_Specific(X))))) | |||
7548 | return true; | |||
7549 | ||||
7550 | // X = sub (A, B), Y = sub (B, A) || X = sub nsw (A, B), Y = sub nsw (B, A) | |||
7551 | Value *A, *B; | |||
7552 | return (!NeedNSW && (match(X, m_Sub(m_Value(A), m_Value(B))) && | |||
7553 | match(Y, m_Sub(m_Specific(B), m_Specific(A))))) || | |||
7554 | (NeedNSW && (match(X, m_NSWSub(m_Value(A), m_Value(B))) && | |||
7555 | match(Y, m_NSWSub(m_Specific(B), m_Specific(A))))); | |||
7556 | } | |||
7557 | ||||
7558 | static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred, | |||
7559 | FastMathFlags FMF, | |||
7560 | Value *CmpLHS, Value *CmpRHS, | |||
7561 | Value *TrueVal, Value *FalseVal, | |||
7562 | Value *&LHS, Value *&RHS, | |||
7563 | unsigned Depth) { | |||
7564 | bool HasMismatchedZeros = false; | |||
7565 | if (CmpInst::isFPPredicate(Pred)) { | |||
7566 | // IEEE-754 ignores the sign of 0.0 in comparisons. So if the select has one | |||
7567 | // 0.0 operand, set the compare's 0.0 operands to that same value for the | |||
7568 | // purpose of identifying min/max. Disregard vector constants with undefined | |||
7569 | // elements because those can not be back-propagated for analysis. | |||
7570 | Value *OutputZeroVal = nullptr; | |||
7571 | if (match(TrueVal, m_AnyZeroFP()) && !match(FalseVal, m_AnyZeroFP()) && | |||
7572 | !cast<Constant>(TrueVal)->containsUndefOrPoisonElement()) | |||
7573 | OutputZeroVal = TrueVal; | |||
7574 | else if (match(FalseVal, m_AnyZeroFP()) && !match(TrueVal, m_AnyZeroFP()) && | |||
7575 | !cast<Constant>(FalseVal)->containsUndefOrPoisonElement()) | |||
7576 | OutputZeroVal = FalseVal; | |||
7577 | ||||
7578 | if (OutputZeroVal) { | |||
7579 | if (match(CmpLHS, m_AnyZeroFP()) && CmpLHS != OutputZeroVal) { | |||
7580 | HasMismatchedZeros = true; | |||
7581 | CmpLHS = OutputZeroVal; | |||
7582 | } | |||
7583 | if (match(CmpRHS, m_AnyZeroFP()) && CmpRHS != OutputZeroVal) { | |||
7584 | HasMismatchedZeros = true; | |||
7585 | CmpRHS = OutputZeroVal; | |||
7586 | } | |||
7587 | } | |||
7588 | } | |||
7589 | ||||
7590 | LHS = CmpLHS; | |||
7591 | RHS = CmpRHS; | |||
7592 | ||||
7593 | // Signed zero may return inconsistent results between implementations. | |||
7594 | // (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0 | |||
7595 | // minNum(0.0, -0.0) // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1) | |||
7596 | // Therefore, we behave conservatively and only proceed if at least one of the | |||
7597 | // operands is known to not be zero or if we don't care about signed zero. | |||
7598 | switch (Pred) { | |||
7599 | default: break; | |||
7600 | case CmpInst::FCMP_OGT: case CmpInst::FCMP_OLT: | |||
7601 | case CmpInst::FCMP_UGT: case CmpInst::FCMP_ULT: | |||
7602 | if (!HasMismatchedZeros) | |||
7603 | break; | |||
7604 | [[fallthrough]]; | |||
7605 | case CmpInst::FCMP_OGE: case CmpInst::FCMP_OLE: | |||
7606 | case CmpInst::FCMP_UGE: case CmpInst::FCMP_ULE: | |||
7607 | if (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && | |||
7608 | !isKnownNonZero(CmpRHS)) | |||
7609 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7610 | } | |||
7611 | ||||
7612 | SelectPatternNaNBehavior NaNBehavior = SPNB_NA; | |||
7613 | bool Ordered = false; | |||
7614 | ||||
7615 | // When given one NaN and one non-NaN input: | |||
7616 | // - maxnum/minnum (C99 fmaxf()/fminf()) return the non-NaN input. | |||
7617 | // - A simple C99 (a < b ? a : b) construction will return 'b' (as the | |||
7618 | // ordered comparison fails), which could be NaN or non-NaN. | |||
7619 | // so here we discover exactly what NaN behavior is required/accepted. | |||
7620 | if (CmpInst::isFPPredicate(Pred)) { | |||
7621 | bool LHSSafe = isKnownNonNaN(CmpLHS, FMF); | |||
7622 | bool RHSSafe = isKnownNonNaN(CmpRHS, FMF); | |||
7623 | ||||
7624 | if (LHSSafe && RHSSafe) { | |||
7625 | // Both operands are known non-NaN. | |||
7626 | NaNBehavior = SPNB_RETURNS_ANY; | |||
7627 | } else if (CmpInst::isOrdered(Pred)) { | |||
7628 | // An ordered comparison will return false when given a NaN, so it | |||
7629 | // returns the RHS. | |||
7630 | Ordered = true; | |||
7631 | if (LHSSafe) | |||
7632 | // LHS is non-NaN, so if RHS is NaN then NaN will be returned. | |||
7633 | NaNBehavior = SPNB_RETURNS_NAN; | |||
7634 | else if (RHSSafe) | |||
7635 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
7636 | else | |||
7637 | // Completely unsafe. | |||
7638 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7639 | } else { | |||
7640 | Ordered = false; | |||
7641 | // An unordered comparison will return true when given a NaN, so it | |||
7642 | // returns the LHS. | |||
7643 | if (LHSSafe) | |||
7644 | // LHS is non-NaN, so if RHS is NaN then non-NaN will be returned. | |||
7645 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
7646 | else if (RHSSafe) | |||
7647 | NaNBehavior = SPNB_RETURNS_NAN; | |||
7648 | else | |||
7649 | // Completely unsafe. | |||
7650 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7651 | } | |||
7652 | } | |||
7653 | ||||
7654 | if (TrueVal == CmpRHS && FalseVal == CmpLHS) { | |||
7655 | std::swap(CmpLHS, CmpRHS); | |||
7656 | Pred = CmpInst::getSwappedPredicate(Pred); | |||
7657 | if (NaNBehavior == SPNB_RETURNS_NAN) | |||
7658 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
7659 | else if (NaNBehavior == SPNB_RETURNS_OTHER) | |||
7660 | NaNBehavior = SPNB_RETURNS_NAN; | |||
7661 | Ordered = !Ordered; | |||
7662 | } | |||
7663 | ||||
7664 | // ([if]cmp X, Y) ? X : Y | |||
7665 | if (TrueVal == CmpLHS && FalseVal == CmpRHS) { | |||
7666 | switch (Pred) { | |||
7667 | default: return {SPF_UNKNOWN, SPNB_NA, false}; // Equality. | |||
7668 | case ICmpInst::ICMP_UGT: | |||
7669 | case ICmpInst::ICMP_UGE: return {SPF_UMAX, SPNB_NA, false}; | |||
7670 | case ICmpInst::ICMP_SGT: | |||
7671 | case ICmpInst::ICMP_SGE: return {SPF_SMAX, SPNB_NA, false}; | |||
7672 | case ICmpInst::ICMP_ULT: | |||
7673 | case ICmpInst::ICMP_ULE: return {SPF_UMIN, SPNB_NA, false}; | |||
7674 | case ICmpInst::ICMP_SLT: | |||
7675 | case ICmpInst::ICMP_SLE: return {SPF_SMIN, SPNB_NA, false}; | |||
7676 | case FCmpInst::FCMP_UGT: | |||
7677 | case FCmpInst::FCMP_UGE: | |||
7678 | case FCmpInst::FCMP_OGT: | |||
7679 | case FCmpInst::FCMP_OGE: return {SPF_FMAXNUM, NaNBehavior, Ordered}; | |||
7680 | case FCmpInst::FCMP_ULT: | |||
7681 | case FCmpInst::FCMP_ULE: | |||
7682 | case FCmpInst::FCMP_OLT: | |||
7683 | case FCmpInst::FCMP_OLE: return {SPF_FMINNUM, NaNBehavior, Ordered}; | |||
7684 | } | |||
7685 | } | |||
7686 | ||||
7687 | if (isKnownNegation(TrueVal, FalseVal)) { | |||
7688 | // Sign-extending LHS does not change its sign, so TrueVal/FalseVal can | |||
7689 | // match against either LHS or sext(LHS). | |||
7690 | auto MaybeSExtCmpLHS = | |||
7691 | m_CombineOr(m_Specific(CmpLHS), m_SExt(m_Specific(CmpLHS))); | |||
7692 | auto ZeroOrAllOnes = m_CombineOr(m_ZeroInt(), m_AllOnes()); | |||
7693 | auto ZeroOrOne = m_CombineOr(m_ZeroInt(), m_One()); | |||
7694 | if (match(TrueVal, MaybeSExtCmpLHS)) { | |||
7695 | // Set the return values. If the compare uses the negated value (-X >s 0), | |||
7696 | // swap the return values because the negated value is always 'RHS'. | |||
7697 | LHS = TrueVal; | |||
7698 | RHS = FalseVal; | |||
7699 | if (match(CmpLHS, m_Neg(m_Specific(FalseVal)))) | |||
7700 | std::swap(LHS, RHS); | |||
7701 | ||||
7702 | // (X >s 0) ? X : -X or (X >s -1) ? X : -X --> ABS(X) | |||
7703 | // (-X >s 0) ? -X : X or (-X >s -1) ? -X : X --> ABS(X) | |||
7704 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) | |||
7705 | return {SPF_ABS, SPNB_NA, false}; | |||
7706 | ||||
7707 | // (X >=s 0) ? X : -X or (X >=s 1) ? X : -X --> ABS(X) | |||
7708 | if (Pred == ICmpInst::ICMP_SGE && match(CmpRHS, ZeroOrOne)) | |||
7709 | return {SPF_ABS, SPNB_NA, false}; | |||
7710 | ||||
7711 | // (X <s 0) ? X : -X or (X <s 1) ? X : -X --> NABS(X) | |||
7712 | // (-X <s 0) ? -X : X or (-X <s 1) ? -X : X --> NABS(X) | |||
7713 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) | |||
7714 | return {SPF_NABS, SPNB_NA, false}; | |||
7715 | } | |||
7716 | else if (match(FalseVal, MaybeSExtCmpLHS)) { | |||
7717 | // Set the return values. If the compare uses the negated value (-X >s 0), | |||
7718 | // swap the return values because the negated value is always 'RHS'. | |||
7719 | LHS = FalseVal; | |||
7720 | RHS = TrueVal; | |||
7721 | if (match(CmpLHS, m_Neg(m_Specific(TrueVal)))) | |||
7722 | std::swap(LHS, RHS); | |||
7723 | ||||
7724 | // (X >s 0) ? -X : X or (X >s -1) ? -X : X --> NABS(X) | |||
7725 | // (-X >s 0) ? X : -X or (-X >s -1) ? X : -X --> NABS(X) | |||
7726 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) | |||
7727 | return {SPF_NABS, SPNB_NA, false}; | |||
7728 | ||||
7729 | // (X <s 0) ? -X : X or (X <s 1) ? -X : X --> ABS(X) | |||
7730 | // (-X <s 0) ? X : -X or (-X <s 1) ? X : -X --> ABS(X) | |||
7731 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) | |||
7732 | return {SPF_ABS, SPNB_NA, false}; | |||
7733 | } | |||
7734 | } | |||
7735 | ||||
7736 | if (CmpInst::isIntPredicate(Pred)) | |||
7737 | return matchMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS, Depth); | |||
7738 | ||||
7739 | // According to (IEEE 754-2008 5.3.1), minNum(0.0, -0.0) and similar | |||
7740 | // may return either -0.0 or 0.0, so fcmp/select pair has stricter | |||
7741 | // semantics than minNum. Be conservative in such case. | |||
7742 | if (NaNBehavior != SPNB_RETURNS_ANY || | |||
7743 | (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && | |||
7744 | !isKnownNonZero(CmpRHS))) | |||
7745 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7746 | ||||
7747 | return matchFastFloatClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS); | |||
7748 | } | |||
7749 | ||||
7750 | /// Helps to match a select pattern in case of a type mismatch. | |||
7751 | /// | |||
7752 | /// The function processes the case when type of true and false values of a | |||
7753 | /// select instruction differs from type of the cmp instruction operands because | |||
7754 | /// of a cast instruction. The function checks if it is legal to move the cast | |||
7755 | /// operation after "select". If yes, it returns the new second value of | |||
7756 | /// "select" (with the assumption that cast is moved): | |||
7757 | /// 1. As operand of cast instruction when both values of "select" are same cast | |||
7758 | /// instructions. | |||
7759 | /// 2. As restored constant (by applying reverse cast operation) when the first | |||
7760 | /// value of the "select" is a cast operation and the second value is a | |||
7761 | /// constant. | |||
7762 | /// NOTE: We return only the new second value because the first value could be | |||
7763 | /// accessed as operand of cast instruction. | |||
7764 | static Value *lookThroughCast(CmpInst *CmpI, Value *V1, Value *V2, | |||
7765 | Instruction::CastOps *CastOp) { | |||
7766 | auto *Cast1 = dyn_cast<CastInst>(V1); | |||
7767 | if (!Cast1) | |||
7768 | return nullptr; | |||
7769 | ||||
7770 | *CastOp = Cast1->getOpcode(); | |||
7771 | Type *SrcTy = Cast1->getSrcTy(); | |||
7772 | if (auto *Cast2 = dyn_cast<CastInst>(V2)) { | |||
7773 | // If V1 and V2 are both the same cast from the same type, look through V1. | |||
7774 | if (*CastOp == Cast2->getOpcode() && SrcTy == Cast2->getSrcTy()) | |||
7775 | return Cast2->getOperand(0); | |||
7776 | return nullptr; | |||
7777 | } | |||
7778 | ||||
7779 | auto *C = dyn_cast<Constant>(V2); | |||
7780 | if (!C) | |||
7781 | return nullptr; | |||
7782 | ||||
7783 | Constant *CastedTo = nullptr; | |||
7784 | switch (*CastOp) { | |||
7785 | case Instruction::ZExt: | |||
7786 | if (CmpI->isUnsigned()) | |||
7787 | CastedTo = ConstantExpr::getTrunc(C, SrcTy); | |||
7788 | break; | |||
7789 | case Instruction::SExt: | |||
7790 | if (CmpI->isSigned()) | |||
7791 | CastedTo = ConstantExpr::getTrunc(C, SrcTy, true); | |||
7792 | break; | |||
7793 | case Instruction::Trunc: | |||
7794 | Constant *CmpConst; | |||
7795 | if (match(CmpI->getOperand(1), m_Constant(CmpConst)) && | |||
7796 | CmpConst->getType() == SrcTy) { | |||
7797 | // Here we have the following case: | |||
7798 | // | |||
7799 | // %cond = cmp iN %x, CmpConst | |||
7800 | // %tr = trunc iN %x to iK | |||
7801 | // %narrowsel = select i1 %cond, iK %t, iK C | |||
7802 | // | |||
7803 | // We can always move trunc after select operation: | |||
7804 | // | |||
7805 | // %cond = cmp iN %x, CmpConst | |||
7806 | // %widesel = select i1 %cond, iN %x, iN CmpConst | |||
7807 | // %tr = trunc iN %widesel to iK | |||
7808 | // | |||
7809 | // Note that C could be extended in any way because we don't care about | |||
7810 | // upper bits after truncation. It can't be abs pattern, because it would | |||
7811 | // look like: | |||
7812 | // | |||
7813 | // select i1 %cond, x, -x. | |||
7814 | // | |||
7815 | // So only min/max pattern could be matched. Such match requires widened C | |||
7816 | // == CmpConst. That is why set widened C = CmpConst, condition trunc | |||
7817 | // CmpConst == C is checked below. | |||
7818 | CastedTo = CmpConst; | |||
7819 | } else { | |||
7820 | CastedTo = ConstantExpr::getIntegerCast(C, SrcTy, CmpI->isSigned()); | |||
7821 | } | |||
7822 | break; | |||
7823 | case Instruction::FPTrunc: | |||
7824 | CastedTo = ConstantExpr::getFPExtend(C, SrcTy, true); | |||
7825 | break; | |||
7826 | case Instruction::FPExt: | |||
7827 | CastedTo = ConstantExpr::getFPTrunc(C, SrcTy, true); | |||
7828 | break; | |||
7829 | case Instruction::FPToUI: | |||
7830 | CastedTo = ConstantExpr::getUIToFP(C, SrcTy, true); | |||
7831 | break; | |||
7832 | case Instruction::FPToSI: | |||
7833 | CastedTo = ConstantExpr::getSIToFP(C, SrcTy, true); | |||
7834 | break; | |||
7835 | case Instruction::UIToFP: | |||
7836 | CastedTo = ConstantExpr::getFPToUI(C, SrcTy, true); | |||
7837 | break; | |||
7838 | case Instruction::SIToFP: | |||
7839 | CastedTo = ConstantExpr::getFPToSI(C, SrcTy, true); | |||
7840 | break; | |||
7841 | default: | |||
7842 | break; | |||
7843 | } | |||
7844 | ||||
7845 | if (!CastedTo) | |||
7846 | return nullptr; | |||
7847 | ||||
7848 | // Make sure the cast doesn't lose any information. | |||
7849 | Constant *CastedBack = | |||
7850 | ConstantExpr::getCast(*CastOp, CastedTo, C->getType(), true); | |||
7851 | if (CastedBack != C) | |||
7852 | return nullptr; | |||
7853 | ||||
7854 | return CastedTo; | |||
7855 | } | |||
7856 | ||||
7857 | SelectPatternResult llvm::matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, | |||
7858 | Instruction::CastOps *CastOp, | |||
7859 | unsigned Depth) { | |||
7860 | if (Depth >= MaxAnalysisRecursionDepth) | |||
7861 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7862 | ||||
7863 | SelectInst *SI = dyn_cast<SelectInst>(V); | |||
7864 | if (!SI) return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7865 | ||||
7866 | CmpInst *CmpI = dyn_cast<CmpInst>(SI->getCondition()); | |||
7867 | if (!CmpI) return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7868 | ||||
7869 | Value *TrueVal = SI->getTrueValue(); | |||
7870 | Value *FalseVal = SI->getFalseValue(); | |||
7871 | ||||
7872 | return llvm::matchDecomposedSelectPattern(CmpI, TrueVal, FalseVal, LHS, RHS, | |||
7873 | CastOp, Depth); | |||
7874 | } | |||
7875 | ||||
7876 | SelectPatternResult llvm::matchDecomposedSelectPattern( | |||
7877 | CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS, | |||
7878 | Instruction::CastOps *CastOp, unsigned Depth) { | |||
7879 | CmpInst::Predicate Pred = CmpI->getPredicate(); | |||
7880 | Value *CmpLHS = CmpI->getOperand(0); | |||
7881 | Value *CmpRHS = CmpI->getOperand(1); | |||
7882 | FastMathFlags FMF; | |||
7883 | if (isa<FPMathOperator>(CmpI)) | |||
7884 | FMF = CmpI->getFastMathFlags(); | |||
7885 | ||||
7886 | // Bail out early. | |||
7887 | if (CmpI->isEquality()) | |||
7888 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
7889 | ||||
7890 | // Deal with type mismatches. | |||
7891 | if (CastOp && CmpLHS->getType() != TrueVal->getType()) { | |||
7892 | if (Value *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp)) { | |||
7893 | // If this is a potential fmin/fmax with a cast to integer, then ignore | |||
7894 | // -0.0 because there is no corresponding integer value. | |||
7895 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) | |||
7896 | FMF.setNoSignedZeros(); | |||
7897 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, | |||
7898 | cast<CastInst>(TrueVal)->getOperand(0), C, | |||
7899 | LHS, RHS, Depth); | |||
7900 | } | |||
7901 | if (Value *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp)) { | |||
7902 | // If this is a potential fmin/fmax with a cast to integer, then ignore | |||
7903 | // -0.0 because there is no corresponding integer value. | |||
7904 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) | |||
7905 | FMF.setNoSignedZeros(); | |||
7906 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, | |||
7907 | C, cast<CastInst>(FalseVal)->getOperand(0), | |||
7908 | LHS, RHS, Depth); | |||
7909 | } | |||
7910 | } | |||
7911 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, TrueVal, FalseVal, | |||
7912 | LHS, RHS, Depth); | |||
7913 | } | |||
7914 | ||||
7915 | CmpInst::Predicate llvm::getMinMaxPred(SelectPatternFlavor SPF, bool Ordered) { | |||
7916 | if (SPF == SPF_SMIN) return ICmpInst::ICMP_SLT; | |||
7917 | if (SPF == SPF_UMIN) return ICmpInst::ICMP_ULT; | |||
7918 | if (SPF == SPF_SMAX) return ICmpInst::ICMP_SGT; | |||
7919 | if (SPF == SPF_UMAX) return ICmpInst::ICMP_UGT; | |||
7920 | if (SPF == SPF_FMINNUM) | |||
7921 | return Ordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; | |||
7922 | if (SPF == SPF_FMAXNUM) | |||
7923 | return Ordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; | |||
7924 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "llvm/lib/Analysis/ValueTracking.cpp" , 7924); | |||
7925 | } | |||
7926 | ||||
7927 | SelectPatternFlavor llvm::getInverseMinMaxFlavor(SelectPatternFlavor SPF) { | |||
7928 | if (SPF == SPF_SMIN) return SPF_SMAX; | |||
7929 | if (SPF == SPF_UMIN) return SPF_UMAX; | |||
7930 | if (SPF == SPF_SMAX) return SPF_SMIN; | |||
7931 | if (SPF == SPF_UMAX) return SPF_UMIN; | |||
7932 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "llvm/lib/Analysis/ValueTracking.cpp" , 7932); | |||
7933 | } | |||
7934 | ||||
7935 | Intrinsic::ID llvm::getInverseMinMaxIntrinsic(Intrinsic::ID MinMaxID) { | |||
7936 | switch (MinMaxID) { | |||
7937 | case Intrinsic::smax: return Intrinsic::smin; | |||
7938 | case Intrinsic::smin: return Intrinsic::smax; | |||
7939 | case Intrinsic::umax: return Intrinsic::umin; | |||
7940 | case Intrinsic::umin: return Intrinsic::umax; | |||
7941 | // Please note that next four intrinsics may produce the same result for | |||
7942 | // original and inverted case even if X != Y due to NaN is handled specially. | |||
7943 | case Intrinsic::maximum: return Intrinsic::minimum; | |||
7944 | case Intrinsic::minimum: return Intrinsic::maximum; | |||
7945 | case Intrinsic::maxnum: return Intrinsic::minnum; | |||
7946 | case Intrinsic::minnum: return Intrinsic::maxnum; | |||
7947 | default: llvm_unreachable("Unexpected intrinsic")::llvm::llvm_unreachable_internal("Unexpected intrinsic", "llvm/lib/Analysis/ValueTracking.cpp" , 7947); | |||
7948 | } | |||
7949 | } | |||
7950 | ||||
7951 | APInt llvm::getMinMaxLimit(SelectPatternFlavor SPF, unsigned BitWidth) { | |||
7952 | switch (SPF) { | |||
7953 | case SPF_SMAX: return APInt::getSignedMaxValue(BitWidth); | |||
7954 | case SPF_SMIN: return APInt::getSignedMinValue(BitWidth); | |||
7955 | case SPF_UMAX: return APInt::getMaxValue(BitWidth); | |||
7956 | case SPF_UMIN: return APInt::getMinValue(BitWidth); | |||
7957 | default: llvm_unreachable("Unexpected flavor")::llvm::llvm_unreachable_internal("Unexpected flavor", "llvm/lib/Analysis/ValueTracking.cpp" , 7957); | |||
7958 | } | |||
7959 | } | |||
7960 | ||||
7961 | std::pair<Intrinsic::ID, bool> | |||
7962 | llvm::canConvertToMinOrMaxIntrinsic(ArrayRef<Value *> VL) { | |||
7963 | // Check if VL contains select instructions that can be folded into a min/max | |||
7964 | // vector intrinsic and return the intrinsic if it is possible. | |||
7965 | // TODO: Support floating point min/max. | |||
7966 | bool AllCmpSingleUse = true; | |||
7967 | SelectPatternResult SelectPattern; | |||
7968 | SelectPattern.Flavor = SPF_UNKNOWN; | |||
7969 | if (all_of(VL, [&SelectPattern, &AllCmpSingleUse](Value *I) { | |||
7970 | Value *LHS, *RHS; | |||
7971 | auto CurrentPattern = matchSelectPattern(I, LHS, RHS); | |||
7972 | if (!SelectPatternResult::isMinOrMax(CurrentPattern.Flavor) || | |||
7973 | CurrentPattern.Flavor == SPF_FMINNUM || | |||
7974 | CurrentPattern.Flavor == SPF_FMAXNUM || | |||
7975 | !I->getType()->isIntOrIntVectorTy()) | |||
7976 | return false; | |||
7977 | if (SelectPattern.Flavor != SPF_UNKNOWN && | |||
7978 | SelectPattern.Flavor != CurrentPattern.Flavor) | |||
7979 | return false; | |||
7980 | SelectPattern = CurrentPattern; | |||
7981 | AllCmpSingleUse &= | |||
7982 | match(I, m_Select(m_OneUse(m_Value()), m_Value(), m_Value())); | |||
7983 | return true; | |||
7984 | })) { | |||
7985 | switch (SelectPattern.Flavor) { | |||
7986 | case SPF_SMIN: | |||
7987 | return {Intrinsic::smin, AllCmpSingleUse}; | |||
7988 | case SPF_UMIN: | |||
7989 | return {Intrinsic::umin, AllCmpSingleUse}; | |||
7990 | case SPF_SMAX: | |||
7991 | return {Intrinsic::smax, AllCmpSingleUse}; | |||
7992 | case SPF_UMAX: | |||
7993 | return {Intrinsic::umax, AllCmpSingleUse}; | |||
7994 | default: | |||
7995 | llvm_unreachable("unexpected select pattern flavor")::llvm::llvm_unreachable_internal("unexpected select pattern flavor" , "llvm/lib/Analysis/ValueTracking.cpp", 7995); | |||
7996 | } | |||
7997 | } | |||
7998 | return {Intrinsic::not_intrinsic, false}; | |||
7999 | } | |||
8000 | ||||
8001 | bool llvm::matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO, | |||
8002 | Value *&Start, Value *&Step) { | |||
8003 | // Handle the case of a simple two-predecessor recurrence PHI. | |||
8004 | // There's a lot more that could theoretically be done here, but | |||
8005 | // this is sufficient to catch some interesting cases. | |||
8006 | if (P->getNumIncomingValues() != 2) | |||
8007 | return false; | |||
8008 | ||||
8009 | for (unsigned i = 0; i != 2; ++i) { | |||
8010 | Value *L = P->getIncomingValue(i); | |||
8011 | Value *R = P->getIncomingValue(!i); | |||
8012 | Operator *LU = dyn_cast<Operator>(L); | |||
8013 | if (!LU) | |||
8014 | continue; | |||
8015 | unsigned Opcode = LU->getOpcode(); | |||
8016 | ||||
8017 | switch (Opcode) { | |||
8018 | default: | |||
8019 | continue; | |||
8020 | // TODO: Expand list -- xor, div, gep, uaddo, etc.. | |||
8021 | case Instruction::LShr: | |||
8022 | case Instruction::AShr: | |||
8023 | case Instruction::Shl: | |||
8024 | case Instruction::Add: | |||
8025 | case Instruction::Sub: | |||
8026 | case Instruction::And: | |||
8027 | case Instruction::Or: | |||
8028 | case Instruction::Mul: | |||
8029 | case Instruction::FMul: { | |||
8030 | Value *LL = LU->getOperand(0); | |||
8031 | Value *LR = LU->getOperand(1); | |||
8032 | // Find a recurrence. | |||
8033 | if (LL == P) | |||
8034 | L = LR; | |||
8035 | else if (LR == P) | |||
8036 | L = LL; | |||
8037 | else | |||
8038 | continue; // Check for recurrence with L and R flipped. | |||
8039 | ||||
8040 | break; // Match! | |||
8041 | } | |||
8042 | }; | |||
8043 | ||||
8044 | // We have matched a recurrence of the form: | |||
8045 | // %iv = [R, %entry], [%iv.next, %backedge] | |||
8046 | // %iv.next = binop %iv, L | |||
8047 | // OR | |||
8048 | // %iv = [R, %entry], [%iv.next, %backedge] | |||
8049 | // %iv.next = binop L, %iv | |||
8050 | BO = cast<BinaryOperator>(LU); | |||
8051 | Start = R; | |||
8052 | Step = L; | |||
8053 | return true; | |||
8054 | } | |||
8055 | return false; | |||
8056 | } | |||
8057 | ||||
8058 | bool llvm::matchSimpleRecurrence(const BinaryOperator *I, PHINode *&P, | |||
8059 | Value *&Start, Value *&Step) { | |||
8060 | BinaryOperator *BO = nullptr; | |||
8061 | P = dyn_cast<PHINode>(I->getOperand(0)); | |||
8062 | if (!P) | |||
8063 | P = dyn_cast<PHINode>(I->getOperand(1)); | |||
8064 | return P && matchSimpleRecurrence(P, BO, Start, Step) && BO == I; | |||
8065 | } | |||
8066 | ||||
8067 | /// Return true if "icmp Pred LHS RHS" is always true. | |||
8068 | static bool isTruePredicate(CmpInst::Predicate Pred, const Value *LHS, | |||
8069 | const Value *RHS, const DataLayout &DL, | |||
8070 | unsigned Depth) { | |||
8071 | if (ICmpInst::isTrueWhenEqual(Pred) && LHS == RHS) | |||
8072 | return true; | |||
8073 | ||||
8074 | switch (Pred) { | |||
8075 | default: | |||
8076 | return false; | |||
8077 | ||||
8078 | case CmpInst::ICMP_SLE: { | |||
8079 | const APInt *C; | |||
8080 | ||||
8081 | // LHS s<= LHS +_{nsw} C if C >= 0 | |||
8082 | if (match(RHS, m_NSWAdd(m_Specific(LHS), m_APInt(C)))) | |||
8083 | return !C->isNegative(); | |||
8084 | return false; | |||
8085 | } | |||
8086 | ||||
8087 | case CmpInst::ICMP_ULE: { | |||
8088 | const APInt *C; | |||
8089 | ||||
8090 | // LHS u<= LHS +_{nuw} C for any C | |||
8091 | if (match(RHS, m_NUWAdd(m_Specific(LHS), m_APInt(C)))) | |||
8092 | return true; | |||
8093 | ||||
8094 | // Match A to (X +_{nuw} CA) and B to (X +_{nuw} CB) | |||
8095 | auto MatchNUWAddsToSameValue = [&](const Value *A, const Value *B, | |||
8096 | const Value *&X, | |||
8097 | const APInt *&CA, const APInt *&CB) { | |||
8098 | if (match(A, m_NUWAdd(m_Value(X), m_APInt(CA))) && | |||
8099 | match(B, m_NUWAdd(m_Specific(X), m_APInt(CB)))) | |||
8100 | return true; | |||
8101 | ||||
8102 | // If X & C == 0 then (X | C) == X +_{nuw} C | |||
8103 | if (match(A, m_Or(m_Value(X), m_APInt(CA))) && | |||
8104 | match(B, m_Or(m_Specific(X), m_APInt(CB)))) { | |||
8105 | KnownBits Known(CA->getBitWidth()); | |||
8106 | computeKnownBits(X, Known, DL, Depth + 1, /*AC*/ nullptr, | |||
8107 | /*CxtI*/ nullptr, /*DT*/ nullptr); | |||
8108 | if (CA->isSubsetOf(Known.Zero) && CB->isSubsetOf(Known.Zero)) | |||
8109 | return true; | |||
8110 | } | |||
8111 | ||||
8112 | return false; | |||
8113 | }; | |||
8114 | ||||
8115 | const Value *X; | |||
8116 | const APInt *CLHS, *CRHS; | |||
8117 | if (MatchNUWAddsToSameValue(LHS, RHS, X, CLHS, CRHS)) | |||
8118 | return CLHS->ule(*CRHS); | |||
8119 | ||||
8120 | return false; | |||
8121 | } | |||
8122 | } | |||
8123 | } | |||
8124 | ||||
8125 | /// Return true if "icmp Pred BLHS BRHS" is true whenever "icmp Pred | |||
8126 | /// ALHS ARHS" is true. Otherwise, return std::nullopt. | |||
8127 | static std::optional<bool> | |||
8128 | isImpliedCondOperands(CmpInst::Predicate Pred, const Value *ALHS, | |||
8129 | const Value *ARHS, const Value *BLHS, const Value *BRHS, | |||
8130 | const DataLayout &DL, unsigned Depth) { | |||
8131 | switch (Pred) { | |||
8132 | default: | |||
8133 | return std::nullopt; | |||
8134 | ||||
8135 | case CmpInst::ICMP_SLT: | |||
8136 | case CmpInst::ICMP_SLE: | |||
8137 | if (isTruePredicate(CmpInst::ICMP_SLE, BLHS, ALHS, DL, Depth) && | |||
8138 | isTruePredicate(CmpInst::ICMP_SLE, ARHS, BRHS, DL, Depth)) | |||
8139 | return true; | |||
8140 | return std::nullopt; | |||
8141 | ||||
8142 | case CmpInst::ICMP_SGT: | |||
8143 | case CmpInst::ICMP_SGE: | |||
8144 | if (isTruePredicate(CmpInst::ICMP_SLE, ALHS, BLHS, DL, Depth) && | |||
8145 | isTruePredicate(CmpInst::ICMP_SLE, BRHS, ARHS, DL, Depth)) | |||
8146 | return true; | |||
8147 | return std::nullopt; | |||
8148 | ||||
8149 | case CmpInst::ICMP_ULT: | |||
8150 | case CmpInst::ICMP_ULE: | |||
8151 | if (isTruePredicate(CmpInst::ICMP_ULE, BLHS, ALHS, DL, Depth) && | |||
8152 | isTruePredicate(CmpInst::ICMP_ULE, ARHS, BRHS, DL, Depth)) | |||
8153 | return true; | |||
8154 | return std::nullopt; | |||
8155 | ||||
8156 | case CmpInst::ICMP_UGT: | |||
8157 | case CmpInst::ICMP_UGE: | |||
8158 | if (isTruePredicate(CmpInst::ICMP_ULE, ALHS, BLHS, DL, Depth) && | |||
8159 | isTruePredicate(CmpInst::ICMP_ULE, BRHS, ARHS, DL, Depth)) | |||
8160 | return true; | |||
8161 | return std::nullopt; | |||
8162 | } | |||
8163 | } | |||
8164 | ||||
8165 | /// Return true if the operands of two compares (expanded as "L0 pred L1" and | |||
8166 | /// "R0 pred R1") match. IsSwappedOps is true when the operands match, but are | |||
8167 | /// swapped. | |||
8168 | static bool areMatchingOperands(const Value *L0, const Value *L1, const Value *R0, | |||
8169 | const Value *R1, bool &AreSwappedOps) { | |||
8170 | bool AreMatchingOps = (L0 == R0 && L1 == R1); | |||
8171 | AreSwappedOps = (L0 == R1 && L1 == R0); | |||
8172 | return AreMatchingOps || AreSwappedOps; | |||
8173 | } | |||
8174 | ||||
8175 | /// Return true if "icmp1 LPred X, Y" implies "icmp2 RPred X, Y" is true. | |||
8176 | /// Return false if "icmp1 LPred X, Y" implies "icmp2 RPred X, Y" is false. | |||
8177 | /// Otherwise, return std::nullopt if we can't infer anything. | |||
8178 | static std::optional<bool> | |||
8179 | isImpliedCondMatchingOperands(CmpInst::Predicate LPred, | |||
8180 | CmpInst::Predicate RPred, bool AreSwappedOps) { | |||
8181 | // Canonicalize the predicate as if the operands were not commuted. | |||
8182 | if (AreSwappedOps) | |||
8183 | RPred = ICmpInst::getSwappedPredicate(RPred); | |||
8184 | ||||
8185 | if (CmpInst::isImpliedTrueByMatchingCmp(LPred, RPred)) | |||
8186 | return true; | |||
8187 | if (CmpInst::isImpliedFalseByMatchingCmp(LPred, RPred)) | |||
8188 | return false; | |||
8189 | ||||
8190 | return std::nullopt; | |||
8191 | } | |||
8192 | ||||
8193 | /// Return true if "icmp LPred X, LC" implies "icmp RPred X, RC" is true. | |||
8194 | /// Return false if "icmp LPred X, LC" implies "icmp RPred X, RC" is false. | |||
8195 | /// Otherwise, return std::nullopt if we can't infer anything. | |||
8196 | static std::optional<bool> isImpliedCondCommonOperandWithConstants( | |||
8197 | CmpInst::Predicate LPred, const APInt &LC, CmpInst::Predicate RPred, | |||
8198 | const APInt &RC) { | |||
8199 | ConstantRange DomCR = ConstantRange::makeExactICmpRegion(LPred, LC); | |||
8200 | ConstantRange CR = ConstantRange::makeExactICmpRegion(RPred, RC); | |||
8201 | ConstantRange Intersection = DomCR.intersectWith(CR); | |||
8202 | ConstantRange Difference = DomCR.difference(CR); | |||
8203 | if (Intersection.isEmptySet()) | |||
8204 | return false; | |||
8205 | if (Difference.isEmptySet()) | |||
8206 | return true; | |||
8207 | return std::nullopt; | |||
8208 | } | |||
8209 | ||||
8210 | /// Return true if LHS implies RHS (expanded to its components as "R0 RPred R1") | |||
8211 | /// is true. Return false if LHS implies RHS is false. Otherwise, return | |||
8212 | /// std::nullopt if we can't infer anything. | |||
8213 | static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS, | |||
8214 | CmpInst::Predicate RPred, | |||
8215 | const Value *R0, const Value *R1, | |||
8216 | const DataLayout &DL, | |||
8217 | bool LHSIsTrue, unsigned Depth) { | |||
8218 | Value *L0 = LHS->getOperand(0); | |||
8219 | Value *L1 = LHS->getOperand(1); | |||
8220 | ||||
8221 | // The rest of the logic assumes the LHS condition is true. If that's not the | |||
8222 | // case, invert the predicate to make it so. | |||
8223 | CmpInst::Predicate LPred = | |||
8224 | LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate(); | |||
8225 | ||||
8226 | // Can we infer anything when the two compares have matching operands? | |||
8227 | bool AreSwappedOps; | |||
8228 | if (areMatchingOperands(L0, L1, R0, R1, AreSwappedOps)) | |||
8229 | return isImpliedCondMatchingOperands(LPred, RPred, AreSwappedOps); | |||
8230 | ||||
8231 | // Can we infer anything when the 0-operands match and the 1-operands are | |||
8232 | // constants (not necessarily matching)? | |||
8233 | const APInt *LC, *RC; | |||
8234 | if (L0 == R0 && match(L1, m_APInt(LC)) && match(R1, m_APInt(RC))) | |||
8235 | return isImpliedCondCommonOperandWithConstants(LPred, *LC, RPred, *RC); | |||
8236 | ||||
8237 | if (LPred == RPred) | |||
8238 | return isImpliedCondOperands(LPred, L0, L1, R0, R1, DL, Depth); | |||
8239 | ||||
8240 | return std::nullopt; | |||
8241 | } | |||
8242 | ||||
8243 | /// Return true if LHS implies RHS is true. Return false if LHS implies RHS is | |||
8244 | /// false. Otherwise, return std::nullopt if we can't infer anything. We | |||
8245 | /// expect the RHS to be an icmp and the LHS to be an 'and', 'or', or a 'select' | |||
8246 | /// instruction. | |||
8247 | static std::optional<bool> | |||
8248 | isImpliedCondAndOr(const Instruction *LHS, CmpInst::Predicate RHSPred, | |||
8249 | const Value *RHSOp0, const Value *RHSOp1, | |||
8250 | const DataLayout &DL, bool LHSIsTrue, unsigned Depth) { | |||
8251 | // The LHS must be an 'or', 'and', or a 'select' instruction. | |||
8252 | assert((LHS->getOpcode() == Instruction::And ||(static_cast <bool> ((LHS->getOpcode() == Instruction ::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode () == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8255, __extension__ __PRETTY_FUNCTION__ )) | |||
8253 | LHS->getOpcode() == Instruction::Or ||(static_cast <bool> ((LHS->getOpcode() == Instruction ::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode () == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8255, __extension__ __PRETTY_FUNCTION__ )) | |||
8254 | LHS->getOpcode() == Instruction::Select) &&(static_cast <bool> ((LHS->getOpcode() == Instruction ::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode () == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8255, __extension__ __PRETTY_FUNCTION__ )) | |||
8255 | "Expected LHS to be 'and', 'or', or 'select'.")(static_cast <bool> ((LHS->getOpcode() == Instruction ::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode () == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8255, __extension__ __PRETTY_FUNCTION__ )); | |||
8256 | ||||
8257 | assert(Depth <= MaxAnalysisRecursionDepth && "Hit recursion limit")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Hit recursion limit") ? void (0) : __assert_fail ("Depth <= MaxAnalysisRecursionDepth && \"Hit recursion limit\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8257, __extension__ __PRETTY_FUNCTION__ )); | |||
8258 | ||||
8259 | // If the result of an 'or' is false, then we know both legs of the 'or' are | |||
8260 | // false. Similarly, if the result of an 'and' is true, then we know both | |||
8261 | // legs of the 'and' are true. | |||
8262 | const Value *ALHS, *ARHS; | |||
8263 | if ((!LHSIsTrue && match(LHS, m_LogicalOr(m_Value(ALHS), m_Value(ARHS)))) || | |||
8264 | (LHSIsTrue && match(LHS, m_LogicalAnd(m_Value(ALHS), m_Value(ARHS))))) { | |||
8265 | // FIXME: Make this non-recursion. | |||
8266 | if (std::optional<bool> Implication = isImpliedCondition( | |||
8267 | ALHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1)) | |||
8268 | return Implication; | |||
8269 | if (std::optional<bool> Implication = isImpliedCondition( | |||
8270 | ARHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1)) | |||
8271 | return Implication; | |||
8272 | return std::nullopt; | |||
8273 | } | |||
8274 | return std::nullopt; | |||
8275 | } | |||
8276 | ||||
8277 | std::optional<bool> | |||
8278 | llvm::isImpliedCondition(const Value *LHS, CmpInst::Predicate RHSPred, | |||
8279 | const Value *RHSOp0, const Value *RHSOp1, | |||
8280 | const DataLayout &DL, bool LHSIsTrue, unsigned Depth) { | |||
8281 | // Bail out when we hit the limit. | |||
8282 | if (Depth == MaxAnalysisRecursionDepth) | |||
8283 | return std::nullopt; | |||
8284 | ||||
8285 | // A mismatch occurs when we compare a scalar cmp to a vector cmp, for | |||
8286 | // example. | |||
8287 | if (RHSOp0->getType()->isVectorTy() != LHS->getType()->isVectorTy()) | |||
8288 | return std::nullopt; | |||
8289 | ||||
8290 | assert(LHS->getType()->isIntOrIntVectorTy(1) &&(static_cast <bool> (LHS->getType()->isIntOrIntVectorTy (1) && "Expected integer type only!") ? void (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy(1) && \"Expected integer type only!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8291, __extension__ __PRETTY_FUNCTION__ )) | |||
8291 | "Expected integer type only!")(static_cast <bool> (LHS->getType()->isIntOrIntVectorTy (1) && "Expected integer type only!") ? void (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy(1) && \"Expected integer type only!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8291, __extension__ __PRETTY_FUNCTION__ )); | |||
8292 | ||||
8293 | // Both LHS and RHS are icmps. | |||
8294 | const ICmpInst *LHSCmp = dyn_cast<ICmpInst>(LHS); | |||
8295 | if (LHSCmp) | |||
8296 | return isImpliedCondICmps(LHSCmp, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, | |||
8297 | Depth); | |||
8298 | ||||
8299 | /// The LHS should be an 'or', 'and', or a 'select' instruction. We expect | |||
8300 | /// the RHS to be an icmp. | |||
8301 | /// FIXME: Add support for and/or/select on the RHS. | |||
8302 | if (const Instruction *LHSI = dyn_cast<Instruction>(LHS)) { | |||
8303 | if ((LHSI->getOpcode() == Instruction::And || | |||
8304 | LHSI->getOpcode() == Instruction::Or || | |||
8305 | LHSI->getOpcode() == Instruction::Select)) | |||
8306 | return isImpliedCondAndOr(LHSI, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, | |||
8307 | Depth); | |||
8308 | } | |||
8309 | return std::nullopt; | |||
8310 | } | |||
8311 | ||||
8312 | std::optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS, | |||
8313 | const DataLayout &DL, | |||
8314 | bool LHSIsTrue, unsigned Depth) { | |||
8315 | // LHS ==> RHS by definition | |||
8316 | if (LHS == RHS) | |||
8317 | return LHSIsTrue; | |||
8318 | ||||
8319 | if (const ICmpInst *RHSCmp = dyn_cast<ICmpInst>(RHS)) | |||
8320 | return isImpliedCondition(LHS, RHSCmp->getPredicate(), | |||
8321 | RHSCmp->getOperand(0), RHSCmp->getOperand(1), DL, | |||
8322 | LHSIsTrue, Depth); | |||
8323 | ||||
8324 | if (Depth == MaxAnalysisRecursionDepth) | |||
8325 | return std::nullopt; | |||
8326 | ||||
8327 | // LHS ==> (RHS1 || RHS2) if LHS ==> RHS1 or LHS ==> RHS2 | |||
8328 | // LHS ==> !(RHS1 && RHS2) if LHS ==> !RHS1 or LHS ==> !RHS2 | |||
8329 | const Value *RHS1, *RHS2; | |||
8330 | if (match(RHS, m_LogicalOr(m_Value(RHS1), m_Value(RHS2)))) { | |||
8331 | if (std::optional<bool> Imp = | |||
8332 | isImpliedCondition(LHS, RHS1, DL, LHSIsTrue, Depth + 1)) | |||
8333 | if (*Imp == true) | |||
8334 | return true; | |||
8335 | if (std::optional<bool> Imp = | |||
8336 | isImpliedCondition(LHS, RHS2, DL, LHSIsTrue, Depth + 1)) | |||
8337 | if (*Imp == true) | |||
8338 | return true; | |||
8339 | } | |||
8340 | if (match(RHS, m_LogicalAnd(m_Value(RHS1), m_Value(RHS2)))) { | |||
8341 | if (std::optional<bool> Imp = | |||
8342 | isImpliedCondition(LHS, RHS1, DL, LHSIsTrue, Depth + 1)) | |||
8343 | if (*Imp == false) | |||
8344 | return false; | |||
8345 | if (std::optional<bool> Imp = | |||
8346 | isImpliedCondition(LHS, RHS2, DL, LHSIsTrue, Depth + 1)) | |||
8347 | if (*Imp == false) | |||
8348 | return false; | |||
8349 | } | |||
8350 | ||||
8351 | return std::nullopt; | |||
8352 | } | |||
8353 | ||||
8354 | // Returns a pair (Condition, ConditionIsTrue), where Condition is a branch | |||
8355 | // condition dominating ContextI or nullptr, if no condition is found. | |||
8356 | static std::pair<Value *, bool> | |||
8357 | getDomPredecessorCondition(const Instruction *ContextI) { | |||
8358 | if (!ContextI || !ContextI->getParent()) | |||
8359 | return {nullptr, false}; | |||
8360 | ||||
8361 | // TODO: This is a poor/cheap way to determine dominance. Should we use a | |||
8362 | // dominator tree (eg, from a SimplifyQuery) instead? | |||
8363 | const BasicBlock *ContextBB = ContextI->getParent(); | |||
8364 | const BasicBlock *PredBB = ContextBB->getSinglePredecessor(); | |||
8365 | if (!PredBB) | |||
8366 | return {nullptr, false}; | |||
8367 | ||||
8368 | // We need a conditional branch in the predecessor. | |||
8369 | Value *PredCond; | |||
8370 | BasicBlock *TrueBB, *FalseBB; | |||
8371 | if (!match(PredBB->getTerminator(), m_Br(m_Value(PredCond), TrueBB, FalseBB))) | |||
8372 | return {nullptr, false}; | |||
8373 | ||||
8374 | // The branch should get simplified. Don't bother simplifying this condition. | |||
8375 | if (TrueBB == FalseBB) | |||
8376 | return {nullptr, false}; | |||
8377 | ||||
8378 | assert((TrueBB == ContextBB || FalseBB == ContextBB) &&(static_cast <bool> ((TrueBB == ContextBB || FalseBB == ContextBB) && "Predecessor block does not point to successor?" ) ? void (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8379, __extension__ __PRETTY_FUNCTION__ )) | |||
8379 | "Predecessor block does not point to successor?")(static_cast <bool> ((TrueBB == ContextBB || FalseBB == ContextBB) && "Predecessor block does not point to successor?" ) ? void (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8379, __extension__ __PRETTY_FUNCTION__ )); | |||
8380 | ||||
8381 | // Is this condition implied by the predecessor condition? | |||
8382 | return {PredCond, TrueBB == ContextBB}; | |||
8383 | } | |||
8384 | ||||
8385 | std::optional<bool> llvm::isImpliedByDomCondition(const Value *Cond, | |||
8386 | const Instruction *ContextI, | |||
8387 | const DataLayout &DL) { | |||
8388 | assert(Cond->getType()->isIntOrIntVectorTy(1) && "Condition must be bool")(static_cast <bool> (Cond->getType()->isIntOrIntVectorTy (1) && "Condition must be bool") ? void (0) : __assert_fail ("Cond->getType()->isIntOrIntVectorTy(1) && \"Condition must be bool\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8388, __extension__ __PRETTY_FUNCTION__ )); | |||
8389 | auto PredCond = getDomPredecessorCondition(ContextI); | |||
8390 | if (PredCond.first) | |||
8391 | return isImpliedCondition(PredCond.first, Cond, DL, PredCond.second); | |||
8392 | return std::nullopt; | |||
8393 | } | |||
8394 | ||||
8395 | std::optional<bool> llvm::isImpliedByDomCondition(CmpInst::Predicate Pred, | |||
8396 | const Value *LHS, | |||
8397 | const Value *RHS, | |||
8398 | const Instruction *ContextI, | |||
8399 | const DataLayout &DL) { | |||
8400 | auto PredCond = getDomPredecessorCondition(ContextI); | |||
8401 | if (PredCond.first) | |||
8402 | return isImpliedCondition(PredCond.first, Pred, LHS, RHS, DL, | |||
8403 | PredCond.second); | |||
8404 | return std::nullopt; | |||
8405 | } | |||
8406 | ||||
8407 | static void setLimitsForBinOp(const BinaryOperator &BO, APInt &Lower, | |||
8408 | APInt &Upper, const InstrInfoQuery &IIQ, | |||
8409 | bool PreferSignedRange) { | |||
8410 | unsigned Width = Lower.getBitWidth(); | |||
8411 | const APInt *C; | |||
8412 | switch (BO.getOpcode()) { | |||
8413 | case Instruction::Add: | |||
8414 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isZero()) { | |||
8415 | bool HasNSW = IIQ.hasNoSignedWrap(&BO); | |||
8416 | bool HasNUW = IIQ.hasNoUnsignedWrap(&BO); | |||
8417 | ||||
8418 | // If the caller expects a signed compare, then try to use a signed range. | |||
8419 | // Otherwise if both no-wraps are set, use the unsigned range because it | |||
8420 | // is never larger than the signed range. Example: | |||
8421 | // "add nuw nsw i8 X, -2" is unsigned [254,255] vs. signed [-128, 125]. | |||
8422 | if (PreferSignedRange && HasNSW && HasNUW) | |||
8423 | HasNUW = false; | |||
8424 | ||||
8425 | if (HasNUW) { | |||
8426 | // 'add nuw x, C' produces [C, UINT_MAX]. | |||
8427 | Lower = *C; | |||
8428 | } else if (HasNSW) { | |||
8429 | if (C->isNegative()) { | |||
8430 | // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C]. | |||
8431 | Lower = APInt::getSignedMinValue(Width); | |||
8432 | Upper = APInt::getSignedMaxValue(Width) + *C + 1; | |||
8433 | } else { | |||
8434 | // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX]. | |||
8435 | Lower = APInt::getSignedMinValue(Width) + *C; | |||
8436 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
8437 | } | |||
8438 | } | |||
8439 | } | |||
8440 | break; | |||
8441 | ||||
8442 | case Instruction::And: | |||
8443 | if (match(BO.getOperand(1), m_APInt(C))) | |||
8444 | // 'and x, C' produces [0, C]. | |||
8445 | Upper = *C + 1; | |||
8446 | break; | |||
8447 | ||||
8448 | case Instruction::Or: | |||
8449 | if (match(BO.getOperand(1), m_APInt(C))) | |||
8450 | // 'or x, C' produces [C, UINT_MAX]. | |||
8451 | Lower = *C; | |||
8452 | break; | |||
8453 | ||||
8454 | case Instruction::AShr: | |||
8455 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { | |||
8456 | // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C]. | |||
8457 | Lower = APInt::getSignedMinValue(Width).ashr(*C); | |||
8458 | Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1; | |||
8459 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
8460 | unsigned ShiftAmount = Width - 1; | |||
8461 | if (!C->isZero() && IIQ.isExact(&BO)) | |||
8462 | ShiftAmount = C->countr_zero(); | |||
8463 | if (C->isNegative()) { | |||
8464 | // 'ashr C, x' produces [C, C >> (Width-1)] | |||
8465 | Lower = *C; | |||
8466 | Upper = C->ashr(ShiftAmount) + 1; | |||
8467 | } else { | |||
8468 | // 'ashr C, x' produces [C >> (Width-1), C] | |||
8469 | Lower = C->ashr(ShiftAmount); | |||
8470 | Upper = *C + 1; | |||
8471 | } | |||
8472 | } | |||
8473 | break; | |||
8474 | ||||
8475 | case Instruction::LShr: | |||
8476 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { | |||
8477 | // 'lshr x, C' produces [0, UINT_MAX >> C]. | |||
8478 | Upper = APInt::getAllOnes(Width).lshr(*C) + 1; | |||
8479 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
8480 | // 'lshr C, x' produces [C >> (Width-1), C]. | |||
8481 | unsigned ShiftAmount = Width - 1; | |||
8482 | if (!C->isZero() && IIQ.isExact(&BO)) | |||
8483 | ShiftAmount = C->countr_zero(); | |||
8484 | Lower = C->lshr(ShiftAmount); | |||
8485 | Upper = *C + 1; | |||
8486 | } | |||
8487 | break; | |||
8488 | ||||
8489 | case Instruction::Shl: | |||
8490 | if (match(BO.getOperand(0), m_APInt(C))) { | |||
8491 | if (IIQ.hasNoUnsignedWrap(&BO)) { | |||
8492 | // 'shl nuw C, x' produces [C, C << CLZ(C)] | |||
8493 | Lower = *C; | |||
8494 | Upper = Lower.shl(Lower.countl_zero()) + 1; | |||
8495 | } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw? | |||
8496 | if (C->isNegative()) { | |||
8497 | // 'shl nsw C, x' produces [C << CLO(C)-1, C] | |||
8498 | unsigned ShiftAmount = C->countl_one() - 1; | |||
8499 | Lower = C->shl(ShiftAmount); | |||
8500 | Upper = *C + 1; | |||
8501 | } else { | |||
8502 | // 'shl nsw C, x' produces [C, C << CLZ(C)-1] | |||
8503 | unsigned ShiftAmount = C->countl_zero() - 1; | |||
8504 | Lower = *C; | |||
8505 | Upper = C->shl(ShiftAmount) + 1; | |||
8506 | } | |||
8507 | } | |||
8508 | } | |||
8509 | break; | |||
8510 | ||||
8511 | case Instruction::SDiv: | |||
8512 | if (match(BO.getOperand(1), m_APInt(C))) { | |||
8513 | APInt IntMin = APInt::getSignedMinValue(Width); | |||
8514 | APInt IntMax = APInt::getSignedMaxValue(Width); | |||
8515 | if (C->isAllOnes()) { | |||
8516 | // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX] | |||
8517 | // where C != -1 and C != 0 and C != 1 | |||
8518 | Lower = IntMin + 1; | |||
8519 | Upper = IntMax + 1; | |||
8520 | } else if (C->countl_zero() < Width - 1) { | |||
8521 | // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C] | |||
8522 | // where C != -1 and C != 0 and C != 1 | |||
8523 | Lower = IntMin.sdiv(*C); | |||
8524 | Upper = IntMax.sdiv(*C); | |||
8525 | if (Lower.sgt(Upper)) | |||
8526 | std::swap(Lower, Upper); | |||
8527 | Upper = Upper + 1; | |||
8528 | assert(Upper != Lower && "Upper part of range has wrapped!")(static_cast <bool> (Upper != Lower && "Upper part of range has wrapped!" ) ? void (0) : __assert_fail ("Upper != Lower && \"Upper part of range has wrapped!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8528, __extension__ __PRETTY_FUNCTION__ )); | |||
8529 | } | |||
8530 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
8531 | if (C->isMinSignedValue()) { | |||
8532 | // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2]. | |||
8533 | Lower = *C; | |||
8534 | Upper = Lower.lshr(1) + 1; | |||
8535 | } else { | |||
8536 | // 'sdiv C, x' produces [-|C|, |C|]. | |||
8537 | Upper = C->abs() + 1; | |||
8538 | Lower = (-Upper) + 1; | |||
8539 | } | |||
8540 | } | |||
8541 | break; | |||
8542 | ||||
8543 | case Instruction::UDiv: | |||
8544 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isZero()) { | |||
8545 | // 'udiv x, C' produces [0, UINT_MAX / C]. | |||
8546 | Upper = APInt::getMaxValue(Width).udiv(*C) + 1; | |||
8547 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
8548 | // 'udiv C, x' produces [0, C]. | |||
8549 | Upper = *C + 1; | |||
8550 | } | |||
8551 | break; | |||
8552 | ||||
8553 | case Instruction::SRem: | |||
8554 | if (match(BO.getOperand(1), m_APInt(C))) { | |||
8555 | // 'srem x, C' produces (-|C|, |C|). | |||
8556 | Upper = C->abs(); | |||
8557 | Lower = (-Upper) + 1; | |||
8558 | } | |||
8559 | break; | |||
8560 | ||||
8561 | case Instruction::URem: | |||
8562 | if (match(BO.getOperand(1), m_APInt(C))) | |||
8563 | // 'urem x, C' produces [0, C). | |||
8564 | Upper = *C; | |||
8565 | break; | |||
8566 | ||||
8567 | default: | |||
8568 | break; | |||
8569 | } | |||
8570 | } | |||
8571 | ||||
8572 | static ConstantRange getRangeForIntrinsic(const IntrinsicInst &II) { | |||
8573 | unsigned Width = II.getType()->getScalarSizeInBits(); | |||
8574 | const APInt *C; | |||
8575 | switch (II.getIntrinsicID()) { | |||
8576 | case Intrinsic::ctpop: | |||
8577 | case Intrinsic::ctlz: | |||
8578 | case Intrinsic::cttz: | |||
8579 | // Maximum of set/clear bits is the bit width. | |||
8580 | return ConstantRange(APInt::getZero(Width), APInt(Width, Width + 1)); | |||
8581 | case Intrinsic::uadd_sat: | |||
8582 | // uadd.sat(x, C) produces [C, UINT_MAX]. | |||
8583 | if (match(II.getOperand(0), m_APInt(C)) || | |||
8584 | match(II.getOperand(1), m_APInt(C))) | |||
8585 | return ConstantRange::getNonEmpty(*C, APInt::getZero(Width)); | |||
8586 | break; | |||
8587 | case Intrinsic::sadd_sat: | |||
8588 | if (match(II.getOperand(0), m_APInt(C)) || | |||
8589 | match(II.getOperand(1), m_APInt(C))) { | |||
8590 | if (C->isNegative()) | |||
8591 | // sadd.sat(x, -C) produces [SINT_MIN, SINT_MAX + (-C)]. | |||
8592 | return ConstantRange::getNonEmpty(APInt::getSignedMinValue(Width), | |||
8593 | APInt::getSignedMaxValue(Width) + *C + | |||
8594 | 1); | |||
8595 | ||||
8596 | // sadd.sat(x, +C) produces [SINT_MIN + C, SINT_MAX]. | |||
8597 | return ConstantRange::getNonEmpty(APInt::getSignedMinValue(Width) + *C, | |||
8598 | APInt::getSignedMaxValue(Width) + 1); | |||
8599 | } | |||
8600 | break; | |||
8601 | case Intrinsic::usub_sat: | |||
8602 | // usub.sat(C, x) produces [0, C]. | |||
8603 | if (match(II.getOperand(0), m_APInt(C))) | |||
8604 | return ConstantRange::getNonEmpty(APInt::getZero(Width), *C + 1); | |||
8605 | ||||
8606 | // usub.sat(x, C) produces [0, UINT_MAX - C]. | |||
8607 | if (match(II.getOperand(1), m_APInt(C))) | |||
8608 | return ConstantRange::getNonEmpty(APInt::getZero(Width), | |||
8609 | APInt::getMaxValue(Width) - *C + 1); | |||
8610 | break; | |||
8611 | case Intrinsic::ssub_sat: | |||
8612 | if (match(II.getOperand(0), m_APInt(C))) { | |||
8613 | if (C->isNegative()) | |||
8614 | // ssub.sat(-C, x) produces [SINT_MIN, -SINT_MIN + (-C)]. | |||
8615 | return ConstantRange::getNonEmpty(APInt::getSignedMinValue(Width), | |||
8616 | *C - APInt::getSignedMinValue(Width) + | |||
8617 | 1); | |||
8618 | ||||
8619 | // ssub.sat(+C, x) produces [-SINT_MAX + C, SINT_MAX]. | |||
8620 | return ConstantRange::getNonEmpty(*C - APInt::getSignedMaxValue(Width), | |||
8621 | APInt::getSignedMaxValue(Width) + 1); | |||
8622 | } else if (match(II.getOperand(1), m_APInt(C))) { | |||
8623 | if (C->isNegative()) | |||
8624 | // ssub.sat(x, -C) produces [SINT_MIN - (-C), SINT_MAX]: | |||
8625 | return ConstantRange::getNonEmpty(APInt::getSignedMinValue(Width) - *C, | |||
8626 | APInt::getSignedMaxValue(Width) + 1); | |||
8627 | ||||
8628 | // ssub.sat(x, +C) produces [SINT_MIN, SINT_MAX - C]. | |||
8629 | return ConstantRange::getNonEmpty(APInt::getSignedMinValue(Width), | |||
8630 | APInt::getSignedMaxValue(Width) - *C + | |||
8631 | 1); | |||
8632 | } | |||
8633 | break; | |||
8634 | case Intrinsic::umin: | |||
8635 | case Intrinsic::umax: | |||
8636 | case Intrinsic::smin: | |||
8637 | case Intrinsic::smax: | |||
8638 | if (!match(II.getOperand(0), m_APInt(C)) && | |||
8639 | !match(II.getOperand(1), m_APInt(C))) | |||
8640 | break; | |||
8641 | ||||
8642 | switch (II.getIntrinsicID()) { | |||
8643 | case Intrinsic::umin: | |||
8644 | return ConstantRange::getNonEmpty(APInt::getZero(Width), *C + 1); | |||
8645 | case Intrinsic::umax: | |||
8646 | return ConstantRange::getNonEmpty(*C, APInt::getZero(Width)); | |||
8647 | case Intrinsic::smin: | |||
8648 | return ConstantRange::getNonEmpty(APInt::getSignedMinValue(Width), | |||
8649 | *C + 1); | |||
8650 | case Intrinsic::smax: | |||
8651 | return ConstantRange::getNonEmpty(*C, | |||
8652 | APInt::getSignedMaxValue(Width) + 1); | |||
8653 | default: | |||
8654 | llvm_unreachable("Must be min/max intrinsic")::llvm::llvm_unreachable_internal("Must be min/max intrinsic" , "llvm/lib/Analysis/ValueTracking.cpp", 8654); | |||
8655 | } | |||
8656 | break; | |||
8657 | case Intrinsic::abs: | |||
8658 | // If abs of SIGNED_MIN is poison, then the result is [0..SIGNED_MAX], | |||
8659 | // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN. | |||
8660 | if (match(II.getOperand(1), m_One())) | |||
8661 | return ConstantRange(APInt::getZero(Width), | |||
8662 | APInt::getSignedMaxValue(Width) + 1); | |||
8663 | ||||
8664 | return ConstantRange(APInt::getZero(Width), | |||
8665 | APInt::getSignedMinValue(Width) + 1); | |||
8666 | case Intrinsic::vscale: | |||
8667 | if (!II.getParent() || !II.getFunction()) | |||
8668 | break; | |||
8669 | return getVScaleRange(II.getFunction(), Width); | |||
8670 | default: | |||
8671 | break; | |||
8672 | } | |||
8673 | ||||
8674 | return ConstantRange::getFull(Width); | |||
8675 | } | |||
8676 | ||||
8677 | static void setLimitsForSelectPattern(const SelectInst &SI, APInt &Lower, | |||
8678 | APInt &Upper, const InstrInfoQuery &IIQ) { | |||
8679 | const Value *LHS = nullptr, *RHS = nullptr; | |||
8680 | SelectPatternResult R = matchSelectPattern(&SI, LHS, RHS); | |||
8681 | if (R.Flavor == SPF_UNKNOWN) | |||
8682 | return; | |||
8683 | ||||
8684 | unsigned BitWidth = SI.getType()->getScalarSizeInBits(); | |||
8685 | ||||
8686 | if (R.Flavor == SelectPatternFlavor::SPF_ABS) { | |||
8687 | // If the negation part of the abs (in RHS) has the NSW flag, | |||
8688 | // then the result of abs(X) is [0..SIGNED_MAX], | |||
8689 | // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN. | |||
8690 | Lower = APInt::getZero(BitWidth); | |||
8691 | if (match(RHS, m_Neg(m_Specific(LHS))) && | |||
8692 | IIQ.hasNoSignedWrap(cast<Instruction>(RHS))) | |||
8693 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; | |||
8694 | else | |||
8695 | Upper = APInt::getSignedMinValue(BitWidth) + 1; | |||
8696 | return; | |||
8697 | } | |||
8698 | ||||
8699 | if (R.Flavor == SelectPatternFlavor::SPF_NABS) { | |||
8700 | // The result of -abs(X) is <= 0. | |||
8701 | Lower = APInt::getSignedMinValue(BitWidth); | |||
8702 | Upper = APInt(BitWidth, 1); | |||
8703 | return; | |||
8704 | } | |||
8705 | ||||
8706 | const APInt *C; | |||
8707 | if (!match(LHS, m_APInt(C)) && !match(RHS, m_APInt(C))) | |||
8708 | return; | |||
8709 | ||||
8710 | switch (R.Flavor) { | |||
8711 | case SPF_UMIN: | |||
8712 | Upper = *C + 1; | |||
8713 | break; | |||
8714 | case SPF_UMAX: | |||
8715 | Lower = *C; | |||
8716 | break; | |||
8717 | case SPF_SMIN: | |||
8718 | Lower = APInt::getSignedMinValue(BitWidth); | |||
8719 | Upper = *C + 1; | |||
8720 | break; | |||
8721 | case SPF_SMAX: | |||
8722 | Lower = *C; | |||
8723 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; | |||
8724 | break; | |||
8725 | default: | |||
8726 | break; | |||
8727 | } | |||
8728 | } | |||
8729 | ||||
8730 | static void setLimitForFPToI(const Instruction *I, APInt &Lower, APInt &Upper) { | |||
8731 | // The maximum representable value of a half is 65504. For floats the maximum | |||
8732 | // value is 3.4e38 which requires roughly 129 bits. | |||
8733 | unsigned BitWidth = I->getType()->getScalarSizeInBits(); | |||
8734 | if (!I->getOperand(0)->getType()->getScalarType()->isHalfTy()) | |||
8735 | return; | |||
8736 | if (isa<FPToSIInst>(I) && BitWidth >= 17) { | |||
8737 | Lower = APInt(BitWidth, -65504); | |||
8738 | Upper = APInt(BitWidth, 65505); | |||
8739 | } | |||
8740 | ||||
8741 | if (isa<FPToUIInst>(I) && BitWidth >= 16) { | |||
8742 | // For a fptoui the lower limit is left as 0. | |||
8743 | Upper = APInt(BitWidth, 65505); | |||
8744 | } | |||
8745 | } | |||
8746 | ||||
8747 | ConstantRange llvm::computeConstantRange(const Value *V, bool ForSigned, | |||
8748 | bool UseInstrInfo, AssumptionCache *AC, | |||
8749 | const Instruction *CtxI, | |||
8750 | const DominatorTree *DT, | |||
8751 | unsigned Depth) { | |||
8752 | assert(V->getType()->isIntOrIntVectorTy() && "Expected integer instruction")(static_cast <bool> (V->getType()->isIntOrIntVectorTy () && "Expected integer instruction") ? void (0) : __assert_fail ("V->getType()->isIntOrIntVectorTy() && \"Expected integer instruction\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8752, __extension__ __PRETTY_FUNCTION__ )); | |||
8753 | ||||
8754 | if (Depth == MaxAnalysisRecursionDepth) | |||
8755 | return ConstantRange::getFull(V->getType()->getScalarSizeInBits()); | |||
8756 | ||||
8757 | const APInt *C; | |||
8758 | if (match(V, m_APInt(C))) | |||
8759 | return ConstantRange(*C); | |||
8760 | ||||
8761 | InstrInfoQuery IIQ(UseInstrInfo); | |||
8762 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); | |||
8763 | ConstantRange CR = ConstantRange::getFull(BitWidth); | |||
8764 | if (auto *BO = dyn_cast<BinaryOperator>(V)) { | |||
8765 | APInt Lower = APInt(BitWidth, 0); | |||
8766 | APInt Upper = APInt(BitWidth, 0); | |||
8767 | // TODO: Return ConstantRange. | |||
8768 | setLimitsForBinOp(*BO, Lower, Upper, IIQ, ForSigned); | |||
8769 | CR = ConstantRange::getNonEmpty(Lower, Upper); | |||
8770 | } else if (auto *II = dyn_cast<IntrinsicInst>(V)) | |||
8771 | CR = getRangeForIntrinsic(*II); | |||
8772 | else if (auto *SI = dyn_cast<SelectInst>(V)) { | |||
8773 | APInt Lower = APInt(BitWidth, 0); | |||
8774 | APInt Upper = APInt(BitWidth, 0); | |||
8775 | // TODO: Return ConstantRange. | |||
8776 | setLimitsForSelectPattern(*SI, Lower, Upper, IIQ); | |||
8777 | CR = ConstantRange::getNonEmpty(Lower, Upper); | |||
8778 | } else if (isa<FPToUIInst>(V) || isa<FPToSIInst>(V)) { | |||
8779 | APInt Lower = APInt(BitWidth, 0); | |||
8780 | APInt Upper = APInt(BitWidth, 0); | |||
8781 | // TODO: Return ConstantRange. | |||
8782 | setLimitForFPToI(cast<Instruction>(V), Lower, Upper); | |||
8783 | CR = ConstantRange::getNonEmpty(Lower, Upper); | |||
8784 | } | |||
8785 | ||||
8786 | if (auto *I = dyn_cast<Instruction>(V)) | |||
8787 | if (auto *Range = IIQ.getMetadata(I, LLVMContext::MD_range)) | |||
8788 | CR = CR.intersectWith(getConstantRangeFromMetadata(*Range)); | |||
8789 | ||||
8790 | if (CtxI && AC) { | |||
8791 | // Try to restrict the range based on information from assumptions. | |||
8792 | for (auto &AssumeVH : AC->assumptionsFor(V)) { | |||
8793 | if (!AssumeVH) | |||
8794 | continue; | |||
8795 | CallInst *I = cast<CallInst>(AssumeVH); | |||
8796 | assert(I->getParent()->getParent() == CtxI->getParent()->getParent() &&(static_cast <bool> (I->getParent()->getParent() == CtxI->getParent()->getParent() && "Got assumption for the wrong function!" ) ? void (0) : __assert_fail ("I->getParent()->getParent() == CtxI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8797, __extension__ __PRETTY_FUNCTION__ )) | |||
8797 | "Got assumption for the wrong function!")(static_cast <bool> (I->getParent()->getParent() == CtxI->getParent()->getParent() && "Got assumption for the wrong function!" ) ? void (0) : __assert_fail ("I->getParent()->getParent() == CtxI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8797, __extension__ __PRETTY_FUNCTION__ )); | |||
8798 | assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8799, __extension__ __PRETTY_FUNCTION__ )) | |||
8799 | "must be an assume intrinsic")(static_cast <bool> (I->getCalledFunction()->getIntrinsicID () == Intrinsic::assume && "must be an assume intrinsic" ) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "llvm/lib/Analysis/ValueTracking.cpp", 8799, __extension__ __PRETTY_FUNCTION__ )); | |||
8800 | ||||
8801 | if (!isValidAssumeForContext(I, CtxI, DT)) | |||
8802 | continue; | |||
8803 | Value *Arg = I->getArgOperand(0); | |||
8804 | ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg); | |||
8805 | // Currently we just use information from comparisons. | |||
8806 | if (!Cmp || Cmp->getOperand(0) != V) | |||
8807 | continue; | |||
8808 | // TODO: Set "ForSigned" parameter via Cmp->isSigned()? | |||
8809 | ConstantRange RHS = | |||
8810 | computeConstantRange(Cmp->getOperand(1), /* ForSigned */ false, | |||
8811 | UseInstrInfo, AC, I, DT, Depth + 1); | |||
8812 | CR = CR.intersectWith( | |||
8813 | ConstantRange::makeAllowedICmpRegion(Cmp->getPredicate(), RHS)); | |||
8814 | } | |||
8815 | } | |||
8816 | ||||
8817 | return CR; | |||
8818 | } |