File: | llvm/lib/Analysis/ValueTracking.cpp |
Warning: | line 202, column 31 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/None.h" | |||
19 | #include "llvm/ADT/Optional.h" | |||
20 | #include "llvm/ADT/STLExtras.h" | |||
21 | #include "llvm/ADT/SmallPtrSet.h" | |||
22 | #include "llvm/ADT/SmallSet.h" | |||
23 | #include "llvm/ADT/SmallVector.h" | |||
24 | #include "llvm/ADT/StringRef.h" | |||
25 | #include "llvm/ADT/iterator_range.h" | |||
26 | #include "llvm/Analysis/AliasAnalysis.h" | |||
27 | #include "llvm/Analysis/AssumeBundleQueries.h" | |||
28 | #include "llvm/Analysis/AssumptionCache.h" | |||
29 | #include "llvm/Analysis/EHPersonalities.h" | |||
30 | #include "llvm/Analysis/GuardUtils.h" | |||
31 | #include "llvm/Analysis/InstructionSimplify.h" | |||
32 | #include "llvm/Analysis/Loads.h" | |||
33 | #include "llvm/Analysis/LoopInfo.h" | |||
34 | #include "llvm/Analysis/OptimizationRemarkEmitter.h" | |||
35 | #include "llvm/Analysis/TargetLibraryInfo.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/Function.h" | |||
46 | #include "llvm/IR/GetElementPtrTypeIterator.h" | |||
47 | #include "llvm/IR/GlobalAlias.h" | |||
48 | #include "llvm/IR/GlobalValue.h" | |||
49 | #include "llvm/IR/GlobalVariable.h" | |||
50 | #include "llvm/IR/InstrTypes.h" | |||
51 | #include "llvm/IR/Instruction.h" | |||
52 | #include "llvm/IR/Instructions.h" | |||
53 | #include "llvm/IR/IntrinsicInst.h" | |||
54 | #include "llvm/IR/Intrinsics.h" | |||
55 | #include "llvm/IR/IntrinsicsAArch64.h" | |||
56 | #include "llvm/IR/IntrinsicsRISCV.h" | |||
57 | #include "llvm/IR/IntrinsicsX86.h" | |||
58 | #include "llvm/IR/LLVMContext.h" | |||
59 | #include "llvm/IR/Metadata.h" | |||
60 | #include "llvm/IR/Module.h" | |||
61 | #include "llvm/IR/Operator.h" | |||
62 | #include "llvm/IR/PatternMatch.h" | |||
63 | #include "llvm/IR/Type.h" | |||
64 | #include "llvm/IR/User.h" | |||
65 | #include "llvm/IR/Value.h" | |||
66 | #include "llvm/Support/Casting.h" | |||
67 | #include "llvm/Support/CommandLine.h" | |||
68 | #include "llvm/Support/Compiler.h" | |||
69 | #include "llvm/Support/ErrorHandling.h" | |||
70 | #include "llvm/Support/KnownBits.h" | |||
71 | #include "llvm/Support/MathExtras.h" | |||
72 | #include <algorithm> | |||
73 | #include <array> | |||
74 | #include <cassert> | |||
75 | #include <cstdint> | |||
76 | #include <iterator> | |||
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 | /// Returns the bitwidth of the given scalar or pointer type. For vector types, | |||
88 | /// returns the element type's bitwidth. | |||
89 | static unsigned getBitWidth(Type *Ty, const DataLayout &DL) { | |||
90 | if (unsigned BitWidth = Ty->getScalarSizeInBits()) | |||
91 | return BitWidth; | |||
92 | ||||
93 | return DL.getPointerTypeSizeInBits(Ty); | |||
94 | } | |||
95 | ||||
96 | namespace { | |||
97 | ||||
98 | // Simplifying using an assume can only be done in a particular control-flow | |||
99 | // context (the context instruction provides that context). If an assume and | |||
100 | // the context instruction are not in the same block then the DT helps in | |||
101 | // figuring out if we can use it. | |||
102 | struct Query { | |||
103 | const DataLayout &DL; | |||
104 | AssumptionCache *AC; | |||
105 | const Instruction *CxtI; | |||
106 | const DominatorTree *DT; | |||
107 | ||||
108 | // Unlike the other analyses, this may be a nullptr because not all clients | |||
109 | // provide it currently. | |||
110 | OptimizationRemarkEmitter *ORE; | |||
111 | ||||
112 | /// If true, it is safe to use metadata during simplification. | |||
113 | InstrInfoQuery IIQ; | |||
114 | ||||
115 | Query(const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, | |||
116 | const DominatorTree *DT, bool UseInstrInfo, | |||
117 | OptimizationRemarkEmitter *ORE = nullptr) | |||
118 | : DL(DL), AC(AC), CxtI(CxtI), DT(DT), ORE(ORE), IIQ(UseInstrInfo) {} | |||
119 | }; | |||
120 | ||||
121 | } // end anonymous namespace | |||
122 | ||||
123 | // Given the provided Value and, potentially, a context instruction, return | |||
124 | // the preferred context instruction (if any). | |||
125 | static const Instruction *safeCxtI(const Value *V, const Instruction *CxtI) { | |||
126 | // If we've been provided with a context instruction, then use that (provided | |||
127 | // it has been inserted). | |||
128 | if (CxtI && CxtI->getParent()) | |||
129 | return CxtI; | |||
130 | ||||
131 | // If the value is really an already-inserted instruction, then use that. | |||
132 | CxtI = dyn_cast<Instruction>(V); | |||
133 | if (CxtI && CxtI->getParent()) | |||
134 | return CxtI; | |||
135 | ||||
136 | return nullptr; | |||
137 | } | |||
138 | ||||
139 | static const Instruction *safeCxtI(const Value *V1, const Value *V2, const Instruction *CxtI) { | |||
140 | // If we've been provided with a context instruction, then use that (provided | |||
141 | // it has been inserted). | |||
142 | if (CxtI && CxtI->getParent()) | |||
143 | return CxtI; | |||
144 | ||||
145 | // If the value is really an already-inserted instruction, then use that. | |||
146 | CxtI = dyn_cast<Instruction>(V1); | |||
147 | if (CxtI && CxtI->getParent()) | |||
148 | return CxtI; | |||
149 | ||||
150 | CxtI = dyn_cast<Instruction>(V2); | |||
151 | if (CxtI && CxtI->getParent()) | |||
152 | return CxtI; | |||
153 | ||||
154 | return nullptr; | |||
155 | } | |||
156 | ||||
157 | static bool getShuffleDemandedElts(const ShuffleVectorInst *Shuf, | |||
158 | const APInt &DemandedElts, | |||
159 | APInt &DemandedLHS, APInt &DemandedRHS) { | |||
160 | // The length of scalable vectors is unknown at compile time, thus we | |||
161 | // cannot check their values | |||
162 | if (isa<ScalableVectorType>(Shuf->getType())) | |||
163 | return false; | |||
164 | ||||
165 | int NumElts = | |||
166 | cast<FixedVectorType>(Shuf->getOperand(0)->getType())->getNumElements(); | |||
167 | int NumMaskElts = cast<FixedVectorType>(Shuf->getType())->getNumElements(); | |||
168 | DemandedLHS = DemandedRHS = APInt::getNullValue(NumElts); | |||
169 | if (DemandedElts.isNullValue()) | |||
170 | return true; | |||
171 | // Simple case of a shuffle with zeroinitializer. | |||
172 | if (all_of(Shuf->getShuffleMask(), [](int Elt) { return Elt == 0; })) { | |||
173 | DemandedLHS.setBit(0); | |||
174 | return true; | |||
175 | } | |||
176 | for (int i = 0; i != NumMaskElts; ++i) { | |||
177 | if (!DemandedElts[i]) | |||
178 | continue; | |||
179 | int M = Shuf->getMaskValue(i); | |||
180 | assert(M < (NumElts * 2) && "Invalid shuffle mask constant")(static_cast <bool> (M < (NumElts * 2) && "Invalid shuffle mask constant" ) ? void (0) : __assert_fail ("M < (NumElts * 2) && \"Invalid shuffle mask constant\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 180, __extension__ __PRETTY_FUNCTION__)); | |||
181 | ||||
182 | // For undef elements, we don't know anything about the common state of | |||
183 | // the shuffle result. | |||
184 | if (M == -1) | |||
185 | return false; | |||
186 | if (M < NumElts) | |||
187 | DemandedLHS.setBit(M % NumElts); | |||
188 | else | |||
189 | DemandedRHS.setBit(M % NumElts); | |||
190 | } | |||
191 | ||||
192 | return true; | |||
193 | } | |||
194 | ||||
195 | static void computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
196 | KnownBits &Known, unsigned Depth, const Query &Q); | |||
197 | ||||
198 | static void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth, | |||
199 | const Query &Q) { | |||
200 | // FIXME: We currently have no way to represent the DemandedElts of a scalable | |||
201 | // vector | |||
202 | if (isa<ScalableVectorType>(V->getType())) { | |||
| ||||
203 | Known.resetAll(); | |||
204 | return; | |||
205 | } | |||
206 | ||||
207 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
208 | APInt DemandedElts = | |||
209 | FVTy ? APInt::getAllOnesValue(FVTy->getNumElements()) : APInt(1, 1); | |||
210 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
211 | } | |||
212 | ||||
213 | void llvm::computeKnownBits(const Value *V, KnownBits &Known, | |||
214 | const DataLayout &DL, unsigned Depth, | |||
215 | AssumptionCache *AC, const Instruction *CxtI, | |||
216 | const DominatorTree *DT, | |||
217 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
218 | ::computeKnownBits(V, Known, Depth, | |||
219 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
220 | } | |||
221 | ||||
222 | void llvm::computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
223 | KnownBits &Known, const DataLayout &DL, | |||
224 | unsigned Depth, AssumptionCache *AC, | |||
225 | const Instruction *CxtI, const DominatorTree *DT, | |||
226 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
227 | ::computeKnownBits(V, DemandedElts, Known, Depth, | |||
228 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
229 | } | |||
230 | ||||
231 | static KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
232 | unsigned Depth, const Query &Q); | |||
233 | ||||
234 | static KnownBits computeKnownBits(const Value *V, unsigned Depth, | |||
235 | const Query &Q); | |||
236 | ||||
237 | KnownBits llvm::computeKnownBits(const Value *V, const DataLayout &DL, | |||
238 | unsigned Depth, AssumptionCache *AC, | |||
239 | const Instruction *CxtI, | |||
240 | const DominatorTree *DT, | |||
241 | OptimizationRemarkEmitter *ORE, | |||
242 | bool UseInstrInfo) { | |||
243 | return ::computeKnownBits( | |||
244 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
245 | } | |||
246 | ||||
247 | KnownBits llvm::computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
248 | const DataLayout &DL, unsigned Depth, | |||
249 | AssumptionCache *AC, const Instruction *CxtI, | |||
250 | const DominatorTree *DT, | |||
251 | OptimizationRemarkEmitter *ORE, | |||
252 | bool UseInstrInfo) { | |||
253 | return ::computeKnownBits( | |||
254 | V, DemandedElts, Depth, | |||
255 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
256 | } | |||
257 | ||||
258 | bool llvm::haveNoCommonBitsSet(const Value *LHS, const Value *RHS, | |||
259 | const DataLayout &DL, AssumptionCache *AC, | |||
260 | const Instruction *CxtI, const DominatorTree *DT, | |||
261 | bool UseInstrInfo) { | |||
262 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 263, __extension__ __PRETTY_FUNCTION__)) | |||
263 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 263, __extension__ __PRETTY_FUNCTION__)); | |||
264 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 265, __extension__ __PRETTY_FUNCTION__)) | |||
265 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 265, __extension__ __PRETTY_FUNCTION__)); | |||
266 | // Look for an inverted mask: (X & ~M) op (Y & M). | |||
267 | Value *M; | |||
268 | if (match(LHS, m_c_And(m_Not(m_Value(M)), m_Value())) && | |||
269 | match(RHS, m_c_And(m_Specific(M), m_Value()))) | |||
270 | return true; | |||
271 | if (match(RHS, m_c_And(m_Not(m_Value(M)), m_Value())) && | |||
272 | match(LHS, m_c_And(m_Specific(M), m_Value()))) | |||
273 | return true; | |||
274 | IntegerType *IT = cast<IntegerType>(LHS->getType()->getScalarType()); | |||
275 | KnownBits LHSKnown(IT->getBitWidth()); | |||
276 | KnownBits RHSKnown(IT->getBitWidth()); | |||
277 | computeKnownBits(LHS, LHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
278 | computeKnownBits(RHS, RHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
279 | return KnownBits::haveNoCommonBitsSet(LHSKnown, RHSKnown); | |||
280 | } | |||
281 | ||||
282 | bool llvm::isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI) { | |||
283 | for (const User *U : CxtI->users()) { | |||
284 | if (const ICmpInst *IC = dyn_cast<ICmpInst>(U)) | |||
285 | if (IC->isEquality()) | |||
286 | if (Constant *C = dyn_cast<Constant>(IC->getOperand(1))) | |||
287 | if (C->isNullValue()) | |||
288 | continue; | |||
289 | return false; | |||
290 | } | |||
291 | return true; | |||
292 | } | |||
293 | ||||
294 | static bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, | |||
295 | const Query &Q); | |||
296 | ||||
297 | bool llvm::isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL, | |||
298 | bool OrZero, unsigned Depth, | |||
299 | AssumptionCache *AC, const Instruction *CxtI, | |||
300 | const DominatorTree *DT, bool UseInstrInfo) { | |||
301 | return ::isKnownToBeAPowerOfTwo( | |||
302 | V, OrZero, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
303 | } | |||
304 | ||||
305 | static bool isKnownNonZero(const Value *V, const APInt &DemandedElts, | |||
306 | unsigned Depth, const Query &Q); | |||
307 | ||||
308 | static bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q); | |||
309 | ||||
310 | bool llvm::isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth, | |||
311 | AssumptionCache *AC, const Instruction *CxtI, | |||
312 | const DominatorTree *DT, bool UseInstrInfo) { | |||
313 | return ::isKnownNonZero(V, Depth, | |||
314 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
315 | } | |||
316 | ||||
317 | bool llvm::isKnownNonNegative(const Value *V, const DataLayout &DL, | |||
318 | unsigned Depth, AssumptionCache *AC, | |||
319 | const Instruction *CxtI, const DominatorTree *DT, | |||
320 | bool UseInstrInfo) { | |||
321 | KnownBits Known = | |||
322 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
323 | return Known.isNonNegative(); | |||
324 | } | |||
325 | ||||
326 | bool llvm::isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth, | |||
327 | AssumptionCache *AC, const Instruction *CxtI, | |||
328 | const DominatorTree *DT, bool UseInstrInfo) { | |||
329 | if (auto *CI = dyn_cast<ConstantInt>(V)) | |||
330 | return CI->getValue().isStrictlyPositive(); | |||
331 | ||||
332 | // TODO: We'd doing two recursive queries here. We should factor this such | |||
333 | // that only a single query is needed. | |||
334 | return isKnownNonNegative(V, DL, Depth, AC, CxtI, DT, UseInstrInfo) && | |||
335 | isKnownNonZero(V, DL, Depth, AC, CxtI, DT, UseInstrInfo); | |||
336 | } | |||
337 | ||||
338 | bool llvm::isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth, | |||
339 | AssumptionCache *AC, const Instruction *CxtI, | |||
340 | const DominatorTree *DT, bool UseInstrInfo) { | |||
341 | KnownBits Known = | |||
342 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
343 | return Known.isNegative(); | |||
344 | } | |||
345 | ||||
346 | static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth, | |||
347 | const Query &Q); | |||
348 | ||||
349 | bool llvm::isKnownNonEqual(const Value *V1, const Value *V2, | |||
350 | const DataLayout &DL, AssumptionCache *AC, | |||
351 | const Instruction *CxtI, const DominatorTree *DT, | |||
352 | bool UseInstrInfo) { | |||
353 | return ::isKnownNonEqual(V1, V2, 0, | |||
354 | Query(DL, AC, safeCxtI(V2, V1, CxtI), DT, | |||
355 | UseInstrInfo, /*ORE=*/nullptr)); | |||
356 | } | |||
357 | ||||
358 | static bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, | |||
359 | const Query &Q); | |||
360 | ||||
361 | bool llvm::MaskedValueIsZero(const Value *V, const APInt &Mask, | |||
362 | const DataLayout &DL, unsigned Depth, | |||
363 | AssumptionCache *AC, const Instruction *CxtI, | |||
364 | const DominatorTree *DT, bool UseInstrInfo) { | |||
365 | return ::MaskedValueIsZero( | |||
366 | V, Mask, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
367 | } | |||
368 | ||||
369 | static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts, | |||
370 | unsigned Depth, const Query &Q); | |||
371 | ||||
372 | static unsigned ComputeNumSignBits(const Value *V, unsigned Depth, | |||
373 | const Query &Q) { | |||
374 | // FIXME: We currently have no way to represent the DemandedElts of a scalable | |||
375 | // vector | |||
376 | if (isa<ScalableVectorType>(V->getType())) | |||
377 | return 1; | |||
378 | ||||
379 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
380 | APInt DemandedElts = | |||
381 | FVTy ? APInt::getAllOnesValue(FVTy->getNumElements()) : APInt(1, 1); | |||
382 | return ComputeNumSignBits(V, DemandedElts, Depth, Q); | |||
383 | } | |||
384 | ||||
385 | unsigned llvm::ComputeNumSignBits(const Value *V, const DataLayout &DL, | |||
386 | unsigned Depth, AssumptionCache *AC, | |||
387 | const Instruction *CxtI, | |||
388 | const DominatorTree *DT, bool UseInstrInfo) { | |||
389 | return ::ComputeNumSignBits( | |||
390 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
391 | } | |||
392 | ||||
393 | static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1, | |||
394 | bool NSW, const APInt &DemandedElts, | |||
395 | KnownBits &KnownOut, KnownBits &Known2, | |||
396 | unsigned Depth, const Query &Q) { | |||
397 | computeKnownBits(Op1, DemandedElts, KnownOut, Depth + 1, Q); | |||
398 | ||||
399 | // If one operand is unknown and we have no nowrap information, | |||
400 | // the result will be unknown independently of the second operand. | |||
401 | if (KnownOut.isUnknown() && !NSW) | |||
402 | return; | |||
403 | ||||
404 | computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q); | |||
405 | KnownOut = KnownBits::computeForAddSub(Add, NSW, Known2, KnownOut); | |||
406 | } | |||
407 | ||||
408 | static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW, | |||
409 | const APInt &DemandedElts, KnownBits &Known, | |||
410 | KnownBits &Known2, unsigned Depth, | |||
411 | const Query &Q) { | |||
412 | computeKnownBits(Op1, DemandedElts, Known, Depth + 1, Q); | |||
413 | computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q); | |||
414 | ||||
415 | bool isKnownNegative = false; | |||
416 | bool isKnownNonNegative = false; | |||
417 | // If the multiplication is known not to overflow, compute the sign bit. | |||
418 | if (NSW) { | |||
419 | if (Op0 == Op1) { | |||
420 | // The product of a number with itself is non-negative. | |||
421 | isKnownNonNegative = true; | |||
422 | } else { | |||
423 | bool isKnownNonNegativeOp1 = Known.isNonNegative(); | |||
424 | bool isKnownNonNegativeOp0 = Known2.isNonNegative(); | |||
425 | bool isKnownNegativeOp1 = Known.isNegative(); | |||
426 | bool isKnownNegativeOp0 = Known2.isNegative(); | |||
427 | // The product of two numbers with the same sign is non-negative. | |||
428 | isKnownNonNegative = (isKnownNegativeOp1 && isKnownNegativeOp0) || | |||
429 | (isKnownNonNegativeOp1 && isKnownNonNegativeOp0); | |||
430 | // The product of a negative number and a non-negative number is either | |||
431 | // negative or zero. | |||
432 | if (!isKnownNonNegative) | |||
433 | isKnownNegative = | |||
434 | (isKnownNegativeOp1 && isKnownNonNegativeOp0 && | |||
435 | Known2.isNonZero()) || | |||
436 | (isKnownNegativeOp0 && isKnownNonNegativeOp1 && Known.isNonZero()); | |||
437 | } | |||
438 | } | |||
439 | ||||
440 | Known = KnownBits::mul(Known, Known2); | |||
441 | ||||
442 | // Only make use of no-wrap flags if we failed to compute the sign bit | |||
443 | // directly. This matters if the multiplication always overflows, in | |||
444 | // which case we prefer to follow the result of the direct computation, | |||
445 | // though as the program is invoking undefined behaviour we can choose | |||
446 | // whatever we like here. | |||
447 | if (isKnownNonNegative && !Known.isNegative()) | |||
448 | Known.makeNonNegative(); | |||
449 | else if (isKnownNegative && !Known.isNonNegative()) | |||
450 | Known.makeNegative(); | |||
451 | } | |||
452 | ||||
453 | void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges, | |||
454 | KnownBits &Known) { | |||
455 | unsigned BitWidth = Known.getBitWidth(); | |||
456 | unsigned NumRanges = Ranges.getNumOperands() / 2; | |||
457 | assert(NumRanges >= 1)(static_cast <bool> (NumRanges >= 1) ? void (0) : __assert_fail ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 457, __extension__ __PRETTY_FUNCTION__)); | |||
458 | ||||
459 | Known.Zero.setAllBits(); | |||
460 | Known.One.setAllBits(); | |||
461 | ||||
462 | for (unsigned i = 0; i < NumRanges; ++i) { | |||
463 | ConstantInt *Lower = | |||
464 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 0)); | |||
465 | ConstantInt *Upper = | |||
466 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1)); | |||
467 | ConstantRange Range(Lower->getValue(), Upper->getValue()); | |||
468 | ||||
469 | // The first CommonPrefixBits of all values in Range are equal. | |||
470 | unsigned CommonPrefixBits = | |||
471 | (Range.getUnsignedMax() ^ Range.getUnsignedMin()).countLeadingZeros(); | |||
472 | APInt Mask = APInt::getHighBitsSet(BitWidth, CommonPrefixBits); | |||
473 | APInt UnsignedMax = Range.getUnsignedMax().zextOrTrunc(BitWidth); | |||
474 | Known.One &= UnsignedMax & Mask; | |||
475 | Known.Zero &= ~UnsignedMax & Mask; | |||
476 | } | |||
477 | } | |||
478 | ||||
479 | static bool isEphemeralValueOf(const Instruction *I, const Value *E) { | |||
480 | SmallVector<const Value *, 16> WorkSet(1, I); | |||
481 | SmallPtrSet<const Value *, 32> Visited; | |||
482 | SmallPtrSet<const Value *, 16> EphValues; | |||
483 | ||||
484 | // The instruction defining an assumption's condition itself is always | |||
485 | // considered ephemeral to that assumption (even if it has other | |||
486 | // non-ephemeral users). See r246696's test case for an example. | |||
487 | if (is_contained(I->operands(), E)) | |||
488 | return true; | |||
489 | ||||
490 | while (!WorkSet.empty()) { | |||
491 | const Value *V = WorkSet.pop_back_val(); | |||
492 | if (!Visited.insert(V).second) | |||
493 | continue; | |||
494 | ||||
495 | // If all uses of this value are ephemeral, then so is this value. | |||
496 | if (llvm::all_of(V->users(), [&](const User *U) { | |||
497 | return EphValues.count(U); | |||
498 | })) { | |||
499 | if (V == E) | |||
500 | return true; | |||
501 | ||||
502 | if (V == I || isSafeToSpeculativelyExecute(V)) { | |||
503 | EphValues.insert(V); | |||
504 | if (const User *U = dyn_cast<User>(V)) | |||
505 | append_range(WorkSet, U->operands()); | |||
506 | } | |||
507 | } | |||
508 | } | |||
509 | ||||
510 | return false; | |||
511 | } | |||
512 | ||||
513 | // Is this an intrinsic that cannot be speculated but also cannot trap? | |||
514 | bool llvm::isAssumeLikeIntrinsic(const Instruction *I) { | |||
515 | if (const IntrinsicInst *CI = dyn_cast<IntrinsicInst>(I)) | |||
516 | return CI->isAssumeLikeIntrinsic(); | |||
517 | ||||
518 | return false; | |||
519 | } | |||
520 | ||||
521 | bool llvm::isValidAssumeForContext(const Instruction *Inv, | |||
522 | const Instruction *CxtI, | |||
523 | const DominatorTree *DT) { | |||
524 | // There are two restrictions on the use of an assume: | |||
525 | // 1. The assume must dominate the context (or the control flow must | |||
526 | // reach the assume whenever it reaches the context). | |||
527 | // 2. The context must not be in the assume's set of ephemeral values | |||
528 | // (otherwise we will use the assume to prove that the condition | |||
529 | // feeding the assume is trivially true, thus causing the removal of | |||
530 | // the assume). | |||
531 | ||||
532 | if (Inv->getParent() == CxtI->getParent()) { | |||
533 | // If Inv and CtxI are in the same block, check if the assume (Inv) is first | |||
534 | // in the BB. | |||
535 | if (Inv->comesBefore(CxtI)) | |||
536 | return true; | |||
537 | ||||
538 | // Don't let an assume affect itself - this would cause the problems | |||
539 | // `isEphemeralValueOf` is trying to prevent, and it would also make | |||
540 | // the loop below go out of bounds. | |||
541 | if (Inv == CxtI) | |||
542 | return false; | |||
543 | ||||
544 | // The context comes first, but they're both in the same block. | |||
545 | // Make sure there is nothing in between that might interrupt | |||
546 | // the control flow, not even CxtI itself. | |||
547 | // We limit the scan distance between the assume and its context instruction | |||
548 | // to avoid a compile-time explosion. This limit is chosen arbitrarily, so | |||
549 | // it can be adjusted if needed (could be turned into a cl::opt). | |||
550 | unsigned ScanLimit = 15; | |||
551 | for (BasicBlock::const_iterator I(CxtI), IE(Inv); I != IE; ++I) | |||
552 | if (!isGuaranteedToTransferExecutionToSuccessor(&*I) || --ScanLimit == 0) | |||
553 | return false; | |||
554 | ||||
555 | return !isEphemeralValueOf(Inv, CxtI); | |||
556 | } | |||
557 | ||||
558 | // Inv and CxtI are in different blocks. | |||
559 | if (DT) { | |||
560 | if (DT->dominates(Inv, CxtI)) | |||
561 | return true; | |||
562 | } else if (Inv->getParent() == CxtI->getParent()->getSinglePredecessor()) { | |||
563 | // We don't have a DT, but this trivially dominates. | |||
564 | return true; | |||
565 | } | |||
566 | ||||
567 | return false; | |||
568 | } | |||
569 | ||||
570 | static bool cmpExcludesZero(CmpInst::Predicate Pred, const Value *RHS) { | |||
571 | // v u> y implies v != 0. | |||
572 | if (Pred == ICmpInst::ICMP_UGT) | |||
573 | return true; | |||
574 | ||||
575 | // Special-case v != 0 to also handle v != null. | |||
576 | if (Pred == ICmpInst::ICMP_NE) | |||
577 | return match(RHS, m_Zero()); | |||
578 | ||||
579 | // All other predicates - rely on generic ConstantRange handling. | |||
580 | const APInt *C; | |||
581 | if (!match(RHS, m_APInt(C))) | |||
582 | return false; | |||
583 | ||||
584 | ConstantRange TrueValues = ConstantRange::makeExactICmpRegion(Pred, *C); | |||
585 | return !TrueValues.contains(APInt::getNullValue(C->getBitWidth())); | |||
586 | } | |||
587 | ||||
588 | static bool isKnownNonZeroFromAssume(const Value *V, const Query &Q) { | |||
589 | // Use of assumptions is context-sensitive. If we don't have a context, we | |||
590 | // cannot use them! | |||
591 | if (!Q.AC || !Q.CxtI) | |||
592 | return false; | |||
593 | ||||
594 | if (Q.CxtI && V->getType()->isPointerTy()) { | |||
595 | SmallVector<Attribute::AttrKind, 2> AttrKinds{Attribute::NonNull}; | |||
596 | if (!NullPointerIsDefined(Q.CxtI->getFunction(), | |||
597 | V->getType()->getPointerAddressSpace())) | |||
598 | AttrKinds.push_back(Attribute::Dereferenceable); | |||
599 | ||||
600 | if (getKnowledgeValidInContext(V, AttrKinds, Q.CxtI, Q.DT, Q.AC)) | |||
601 | return true; | |||
602 | } | |||
603 | ||||
604 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { | |||
605 | if (!AssumeVH) | |||
606 | continue; | |||
607 | CallInst *I = cast<CallInst>(AssumeVH); | |||
608 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 609, __extension__ __PRETTY_FUNCTION__)) | |||
609 | "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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 609, __extension__ __PRETTY_FUNCTION__)); | |||
610 | ||||
611 | // Warning: This loop can end up being somewhat performance sensitive. | |||
612 | // We're running this loop for once for each value queried resulting in a | |||
613 | // runtime of ~O(#assumes * #values). | |||
614 | ||||
615 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 616, __extension__ __PRETTY_FUNCTION__)) | |||
616 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 616, __extension__ __PRETTY_FUNCTION__)); | |||
617 | ||||
618 | Value *RHS; | |||
619 | CmpInst::Predicate Pred; | |||
620 | auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V))); | |||
621 | if (!match(I->getArgOperand(0), m_c_ICmp(Pred, m_V, m_Value(RHS)))) | |||
622 | return false; | |||
623 | ||||
624 | if (cmpExcludesZero(Pred, RHS) && isValidAssumeForContext(I, Q.CxtI, Q.DT)) | |||
625 | return true; | |||
626 | } | |||
627 | ||||
628 | return false; | |||
629 | } | |||
630 | ||||
631 | static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known, | |||
632 | unsigned Depth, const Query &Q) { | |||
633 | // Use of assumptions is context-sensitive. If we don't have a context, we | |||
634 | // cannot use them! | |||
635 | if (!Q.AC || !Q.CxtI) | |||
636 | return; | |||
637 | ||||
638 | unsigned BitWidth = Known.getBitWidth(); | |||
639 | ||||
640 | // Refine Known set if the pointer alignment is set by assume bundles. | |||
641 | if (V->getType()->isPointerTy()) { | |||
642 | if (RetainedKnowledge RK = getKnowledgeValidInContext( | |||
643 | V, {Attribute::Alignment}, Q.CxtI, Q.DT, Q.AC)) { | |||
644 | Known.Zero.setLowBits(Log2_32(RK.ArgValue)); | |||
645 | } | |||
646 | } | |||
647 | ||||
648 | // Note that the patterns below need to be kept in sync with the code | |||
649 | // in AssumptionCache::updateAffectedValues. | |||
650 | ||||
651 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { | |||
652 | if (!AssumeVH) | |||
653 | continue; | |||
654 | CallInst *I = cast<CallInst>(AssumeVH); | |||
655 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 656, __extension__ __PRETTY_FUNCTION__)) | |||
656 | "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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 656, __extension__ __PRETTY_FUNCTION__)); | |||
657 | ||||
658 | // Warning: This loop can end up being somewhat performance sensitive. | |||
659 | // We're running this loop for once for each value queried resulting in a | |||
660 | // runtime of ~O(#assumes * #values). | |||
661 | ||||
662 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 663, __extension__ __PRETTY_FUNCTION__)) | |||
663 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 663, __extension__ __PRETTY_FUNCTION__)); | |||
664 | ||||
665 | Value *Arg = I->getArgOperand(0); | |||
666 | ||||
667 | if (Arg == V && isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
668 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 668, __extension__ __PRETTY_FUNCTION__)); | |||
669 | Known.setAllOnes(); | |||
670 | return; | |||
671 | } | |||
672 | if (match(Arg, m_Not(m_Specific(V))) && | |||
673 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
674 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 674, __extension__ __PRETTY_FUNCTION__)); | |||
675 | Known.setAllZero(); | |||
676 | return; | |||
677 | } | |||
678 | ||||
679 | // The remaining tests are all recursive, so bail out if we hit the limit. | |||
680 | if (Depth == MaxAnalysisRecursionDepth) | |||
681 | continue; | |||
682 | ||||
683 | ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg); | |||
684 | if (!Cmp) | |||
685 | continue; | |||
686 | ||||
687 | // We are attempting to compute known bits for the operands of an assume. | |||
688 | // Do not try to use other assumptions for those recursive calls because | |||
689 | // that can lead to mutual recursion and a compile-time explosion. | |||
690 | // An example of the mutual recursion: computeKnownBits can call | |||
691 | // isKnownNonZero which calls computeKnownBitsFromAssume (this function) | |||
692 | // and so on. | |||
693 | Query QueryNoAC = Q; | |||
694 | QueryNoAC.AC = nullptr; | |||
695 | ||||
696 | // Note that ptrtoint may change the bitwidth. | |||
697 | Value *A, *B; | |||
698 | auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V))); | |||
699 | ||||
700 | CmpInst::Predicate Pred; | |||
701 | uint64_t C; | |||
702 | switch (Cmp->getPredicate()) { | |||
703 | default: | |||
704 | break; | |||
705 | case ICmpInst::ICMP_EQ: | |||
706 | // assume(v = a) | |||
707 | if (match(Cmp, m_c_ICmp(Pred, m_V, m_Value(A))) && | |||
708 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
709 | KnownBits RHSKnown = | |||
710 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
711 | Known.Zero |= RHSKnown.Zero; | |||
712 | Known.One |= RHSKnown.One; | |||
713 | // assume(v & b = a) | |||
714 | } else if (match(Cmp, | |||
715 | m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)), m_Value(A))) && | |||
716 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
717 | KnownBits RHSKnown = | |||
718 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
719 | KnownBits MaskKnown = | |||
720 | computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
721 | ||||
722 | // For those bits in the mask that are known to be one, we can propagate | |||
723 | // known bits from the RHS to V. | |||
724 | Known.Zero |= RHSKnown.Zero & MaskKnown.One; | |||
725 | Known.One |= RHSKnown.One & MaskKnown.One; | |||
726 | // assume(~(v & b) = a) | |||
727 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))), | |||
728 | m_Value(A))) && | |||
729 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
730 | KnownBits RHSKnown = | |||
731 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
732 | KnownBits MaskKnown = | |||
733 | computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
734 | ||||
735 | // For those bits in the mask that are known to be one, we can propagate | |||
736 | // inverted known bits from the RHS to V. | |||
737 | Known.Zero |= RHSKnown.One & MaskKnown.One; | |||
738 | Known.One |= RHSKnown.Zero & MaskKnown.One; | |||
739 | // assume(v | b = a) | |||
740 | } else if (match(Cmp, | |||
741 | m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), m_Value(A))) && | |||
742 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
743 | KnownBits RHSKnown = | |||
744 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
745 | KnownBits BKnown = | |||
746 | computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
747 | ||||
748 | // For those bits in B that are known to be zero, we can propagate known | |||
749 | // bits from the RHS to V. | |||
750 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; | |||
751 | Known.One |= RHSKnown.One & BKnown.Zero; | |||
752 | // assume(~(v | b) = a) | |||
753 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))), | |||
754 | m_Value(A))) && | |||
755 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
756 | KnownBits RHSKnown = | |||
757 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
758 | KnownBits BKnown = | |||
759 | computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
760 | ||||
761 | // For those bits in B that are known to be zero, we can propagate | |||
762 | // inverted known bits from the RHS to V. | |||
763 | Known.Zero |= RHSKnown.One & BKnown.Zero; | |||
764 | Known.One |= RHSKnown.Zero & BKnown.Zero; | |||
765 | // assume(v ^ b = a) | |||
766 | } else if (match(Cmp, | |||
767 | m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), m_Value(A))) && | |||
768 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
769 | KnownBits RHSKnown = | |||
770 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
771 | KnownBits BKnown = | |||
772 | computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
773 | ||||
774 | // For those bits in B that are known to be zero, we can propagate known | |||
775 | // bits from the RHS to V. For those bits in B that are known to be one, | |||
776 | // we can propagate inverted known bits from the RHS to V. | |||
777 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; | |||
778 | Known.One |= RHSKnown.One & BKnown.Zero; | |||
779 | Known.Zero |= RHSKnown.One & BKnown.One; | |||
780 | Known.One |= RHSKnown.Zero & BKnown.One; | |||
781 | // assume(~(v ^ b) = a) | |||
782 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))), | |||
783 | m_Value(A))) && | |||
784 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
785 | KnownBits RHSKnown = | |||
786 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
787 | KnownBits BKnown = | |||
788 | computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
789 | ||||
790 | // For those bits in B that are known to be zero, we can propagate | |||
791 | // inverted known bits from the RHS to V. For those bits in B that are | |||
792 | // known to be one, we can propagate known bits from the RHS to V. | |||
793 | Known.Zero |= RHSKnown.One & BKnown.Zero; | |||
794 | Known.One |= RHSKnown.Zero & BKnown.Zero; | |||
795 | Known.Zero |= RHSKnown.Zero & BKnown.One; | |||
796 | Known.One |= RHSKnown.One & BKnown.One; | |||
797 | // assume(v << c = a) | |||
798 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)), | |||
799 | m_Value(A))) && | |||
800 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
801 | KnownBits RHSKnown = | |||
802 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
803 | ||||
804 | // For those bits in RHS that are known, we can propagate them to known | |||
805 | // bits in V shifted to the right by C. | |||
806 | RHSKnown.Zero.lshrInPlace(C); | |||
807 | Known.Zero |= RHSKnown.Zero; | |||
808 | RHSKnown.One.lshrInPlace(C); | |||
809 | Known.One |= RHSKnown.One; | |||
810 | // assume(~(v << c) = a) | |||
811 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))), | |||
812 | m_Value(A))) && | |||
813 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
814 | KnownBits RHSKnown = | |||
815 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
816 | // For those bits in RHS that are known, we can propagate them inverted | |||
817 | // to known bits in V shifted to the right by C. | |||
818 | RHSKnown.One.lshrInPlace(C); | |||
819 | Known.Zero |= RHSKnown.One; | |||
820 | RHSKnown.Zero.lshrInPlace(C); | |||
821 | Known.One |= RHSKnown.Zero; | |||
822 | // assume(v >> c = a) | |||
823 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shr(m_V, m_ConstantInt(C)), | |||
824 | m_Value(A))) && | |||
825 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
826 | KnownBits RHSKnown = | |||
827 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
828 | // For those bits in RHS that are known, we can propagate them to known | |||
829 | // bits in V shifted to the right by C. | |||
830 | Known.Zero |= RHSKnown.Zero << C; | |||
831 | Known.One |= RHSKnown.One << C; | |||
832 | // assume(~(v >> c) = a) | |||
833 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shr(m_V, m_ConstantInt(C))), | |||
834 | m_Value(A))) && | |||
835 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
836 | KnownBits RHSKnown = | |||
837 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
838 | // For those bits in RHS that are known, we can propagate them inverted | |||
839 | // to known bits in V shifted to the right by C. | |||
840 | Known.Zero |= RHSKnown.One << C; | |||
841 | Known.One |= RHSKnown.Zero << C; | |||
842 | } | |||
843 | break; | |||
844 | case ICmpInst::ICMP_SGE: | |||
845 | // assume(v >=_s c) where c is non-negative | |||
846 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
847 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
848 | KnownBits RHSKnown = | |||
849 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
850 | ||||
851 | if (RHSKnown.isNonNegative()) { | |||
852 | // We know that the sign bit is zero. | |||
853 | Known.makeNonNegative(); | |||
854 | } | |||
855 | } | |||
856 | break; | |||
857 | case ICmpInst::ICMP_SGT: | |||
858 | // assume(v >_s c) where c is at least -1. | |||
859 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
860 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
861 | KnownBits RHSKnown = | |||
862 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
863 | ||||
864 | if (RHSKnown.isAllOnes() || RHSKnown.isNonNegative()) { | |||
865 | // We know that the sign bit is zero. | |||
866 | Known.makeNonNegative(); | |||
867 | } | |||
868 | } | |||
869 | break; | |||
870 | case ICmpInst::ICMP_SLE: | |||
871 | // assume(v <=_s c) where c is negative | |||
872 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
873 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
874 | KnownBits RHSKnown = | |||
875 | computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
876 | ||||
877 | if (RHSKnown.isNegative()) { | |||
878 | // We know that the sign bit is one. | |||
879 | Known.makeNegative(); | |||
880 | } | |||
881 | } | |||
882 | break; | |||
883 | case ICmpInst::ICMP_SLT: | |||
884 | // assume(v <_s c) where c is non-positive | |||
885 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
886 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
887 | KnownBits RHSKnown = | |||
888 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
889 | ||||
890 | if (RHSKnown.isZero() || RHSKnown.isNegative()) { | |||
891 | // We know that the sign bit is one. | |||
892 | Known.makeNegative(); | |||
893 | } | |||
894 | } | |||
895 | break; | |||
896 | case ICmpInst::ICMP_ULE: | |||
897 | // assume(v <=_u c) | |||
898 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
899 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
900 | KnownBits RHSKnown = | |||
901 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
902 | ||||
903 | // Whatever high bits in c are zero are known to be zero. | |||
904 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); | |||
905 | } | |||
906 | break; | |||
907 | case ICmpInst::ICMP_ULT: | |||
908 | // assume(v <_u c) | |||
909 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
910 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
911 | KnownBits RHSKnown = | |||
912 | computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth); | |||
913 | ||||
914 | // If the RHS is known zero, then this assumption must be wrong (nothing | |||
915 | // is unsigned less than zero). Signal a conflict and get out of here. | |||
916 | if (RHSKnown.isZero()) { | |||
917 | Known.Zero.setAllBits(); | |||
918 | Known.One.setAllBits(); | |||
919 | break; | |||
920 | } | |||
921 | ||||
922 | // Whatever high bits in c are zero are known to be zero (if c is a power | |||
923 | // of 2, then one more). | |||
924 | if (isKnownToBeAPowerOfTwo(A, false, Depth + 1, QueryNoAC)) | |||
925 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros() + 1); | |||
926 | else | |||
927 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); | |||
928 | } | |||
929 | break; | |||
930 | } | |||
931 | } | |||
932 | ||||
933 | // If assumptions conflict with each other or previous known bits, then we | |||
934 | // have a logical fallacy. It's possible that the assumption is not reachable, | |||
935 | // so this isn't a real bug. On the other hand, the program may have undefined | |||
936 | // behavior, or we might have a bug in the compiler. We can't assert/crash, so | |||
937 | // clear out the known bits, try to warn the user, and hope for the best. | |||
938 | if (Known.Zero.intersects(Known.One)) { | |||
939 | Known.resetAll(); | |||
940 | ||||
941 | if (Q.ORE) | |||
942 | Q.ORE->emit([&]() { | |||
943 | auto *CxtI = const_cast<Instruction *>(Q.CxtI); | |||
944 | return OptimizationRemarkAnalysis("value-tracking", "BadAssumption", | |||
945 | CxtI) | |||
946 | << "Detected conflicting code assumptions. Program may " | |||
947 | "have undefined behavior, or compiler may have " | |||
948 | "internal error."; | |||
949 | }); | |||
950 | } | |||
951 | } | |||
952 | ||||
953 | /// Compute known bits from a shift operator, including those with a | |||
954 | /// non-constant shift amount. Known is the output of this function. Known2 is a | |||
955 | /// pre-allocated temporary with the same bit width as Known and on return | |||
956 | /// contains the known bit of the shift value source. KF is an | |||
957 | /// operator-specific function that, given the known-bits and a shift amount, | |||
958 | /// compute the implied known-bits of the shift operator's result respectively | |||
959 | /// for that shift amount. The results from calling KF are conservatively | |||
960 | /// combined for all permitted shift amounts. | |||
961 | static void computeKnownBitsFromShiftOperator( | |||
962 | const Operator *I, const APInt &DemandedElts, KnownBits &Known, | |||
963 | KnownBits &Known2, unsigned Depth, const Query &Q, | |||
964 | function_ref<KnownBits(const KnownBits &, const KnownBits &)> KF) { | |||
965 | unsigned BitWidth = Known.getBitWidth(); | |||
966 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
967 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
968 | ||||
969 | // Note: We cannot use Known.Zero.getLimitedValue() here, because if | |||
970 | // BitWidth > 64 and any upper bits are known, we'll end up returning the | |||
971 | // limit value (which implies all bits are known). | |||
972 | uint64_t ShiftAmtKZ = Known.Zero.zextOrTrunc(64).getZExtValue(); | |||
973 | uint64_t ShiftAmtKO = Known.One.zextOrTrunc(64).getZExtValue(); | |||
974 | bool ShiftAmtIsConstant = Known.isConstant(); | |||
975 | bool MaxShiftAmtIsOutOfRange = Known.getMaxValue().uge(BitWidth); | |||
976 | ||||
977 | if (ShiftAmtIsConstant) { | |||
978 | Known = KF(Known2, Known); | |||
979 | ||||
980 | // If the known bits conflict, this must be an overflowing left shift, so | |||
981 | // the shift result is poison. We can return anything we want. Choose 0 for | |||
982 | // the best folding opportunity. | |||
983 | if (Known.hasConflict()) | |||
984 | Known.setAllZero(); | |||
985 | ||||
986 | return; | |||
987 | } | |||
988 | ||||
989 | // If the shift amount could be greater than or equal to the bit-width of the | |||
990 | // LHS, the value could be poison, but bail out because the check below is | |||
991 | // expensive. | |||
992 | // TODO: Should we just carry on? | |||
993 | if (MaxShiftAmtIsOutOfRange) { | |||
994 | Known.resetAll(); | |||
995 | return; | |||
996 | } | |||
997 | ||||
998 | // It would be more-clearly correct to use the two temporaries for this | |||
999 | // calculation. Reusing the APInts here to prevent unnecessary allocations. | |||
1000 | Known.resetAll(); | |||
1001 | ||||
1002 | // If we know the shifter operand is nonzero, we can sometimes infer more | |||
1003 | // known bits. However this is expensive to compute, so be lazy about it and | |||
1004 | // only compute it when absolutely necessary. | |||
1005 | Optional<bool> ShifterOperandIsNonZero; | |||
1006 | ||||
1007 | // Early exit if we can't constrain any well-defined shift amount. | |||
1008 | if (!(ShiftAmtKZ & (PowerOf2Ceil(BitWidth) - 1)) && | |||
1009 | !(ShiftAmtKO & (PowerOf2Ceil(BitWidth) - 1))) { | |||
1010 | ShifterOperandIsNonZero = | |||
1011 | isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q); | |||
1012 | if (!*ShifterOperandIsNonZero) | |||
1013 | return; | |||
1014 | } | |||
1015 | ||||
1016 | Known.Zero.setAllBits(); | |||
1017 | Known.One.setAllBits(); | |||
1018 | for (unsigned ShiftAmt = 0; ShiftAmt < BitWidth; ++ShiftAmt) { | |||
1019 | // Combine the shifted known input bits only for those shift amounts | |||
1020 | // compatible with its known constraints. | |||
1021 | if ((ShiftAmt & ~ShiftAmtKZ) != ShiftAmt) | |||
1022 | continue; | |||
1023 | if ((ShiftAmt | ShiftAmtKO) != ShiftAmt) | |||
1024 | continue; | |||
1025 | // If we know the shifter is nonzero, we may be able to infer more known | |||
1026 | // bits. This check is sunk down as far as possible to avoid the expensive | |||
1027 | // call to isKnownNonZero if the cheaper checks above fail. | |||
1028 | if (ShiftAmt == 0) { | |||
1029 | if (!ShifterOperandIsNonZero.hasValue()) | |||
1030 | ShifterOperandIsNonZero = | |||
1031 | isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q); | |||
1032 | if (*ShifterOperandIsNonZero) | |||
1033 | continue; | |||
1034 | } | |||
1035 | ||||
1036 | Known = KnownBits::commonBits( | |||
1037 | Known, KF(Known2, KnownBits::makeConstant(APInt(32, ShiftAmt)))); | |||
1038 | } | |||
1039 | ||||
1040 | // If the known bits conflict, the result is poison. Return a 0 and hope the | |||
1041 | // caller can further optimize that. | |||
1042 | if (Known.hasConflict()) | |||
1043 | Known.setAllZero(); | |||
1044 | } | |||
1045 | ||||
1046 | static void computeKnownBitsFromOperator(const Operator *I, | |||
1047 | const APInt &DemandedElts, | |||
1048 | KnownBits &Known, unsigned Depth, | |||
1049 | const Query &Q) { | |||
1050 | unsigned BitWidth = Known.getBitWidth(); | |||
1051 | ||||
1052 | KnownBits Known2(BitWidth); | |||
1053 | switch (I->getOpcode()) { | |||
| ||||
1054 | default: break; | |||
1055 | case Instruction::Load: | |||
1056 | if (MDNode *MD = | |||
1057 | Q.IIQ.getMetadata(cast<LoadInst>(I), LLVMContext::MD_range)) | |||
1058 | computeKnownBitsFromRangeMetadata(*MD, Known); | |||
1059 | break; | |||
1060 | case Instruction::And: { | |||
1061 | // If either the LHS or the RHS are Zero, the result is zero. | |||
1062 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
1063 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1064 | ||||
1065 | Known &= Known2; | |||
1066 | ||||
1067 | // and(x, add (x, -1)) is a common idiom that always clears the low bit; | |||
1068 | // here we handle the more general case of adding any odd number by | |||
1069 | // matching the form add(x, add(x, y)) where y is odd. | |||
1070 | // TODO: This could be generalized to clearing any bit set in y where the | |||
1071 | // following bit is known to be unset in y. | |||
1072 | Value *X = nullptr, *Y = nullptr; | |||
1073 | if (!Known.Zero[0] && !Known.One[0] && | |||
1074 | match(I, m_c_BinOp(m_Value(X), m_Add(m_Deferred(X), m_Value(Y))))) { | |||
1075 | Known2.resetAll(); | |||
1076 | computeKnownBits(Y, DemandedElts, Known2, Depth + 1, Q); | |||
1077 | if (Known2.countMinTrailingOnes() > 0) | |||
1078 | Known.Zero.setBit(0); | |||
1079 | } | |||
1080 | break; | |||
1081 | } | |||
1082 | case Instruction::Or: | |||
1083 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
1084 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1085 | ||||
1086 | Known |= Known2; | |||
1087 | break; | |||
1088 | case Instruction::Xor: | |||
1089 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); | |||
1090 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1091 | ||||
1092 | Known ^= Known2; | |||
1093 | break; | |||
1094 | case Instruction::Mul: { | |||
1095 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1096 | computeKnownBitsMul(I->getOperand(0), I->getOperand(1), NSW, DemandedElts, | |||
1097 | Known, Known2, Depth, Q); | |||
1098 | break; | |||
1099 | } | |||
1100 | case Instruction::UDiv: { | |||
1101 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1102 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1103 | Known = KnownBits::udiv(Known, Known2); | |||
1104 | break; | |||
1105 | } | |||
1106 | case Instruction::Select: { | |||
1107 | const Value *LHS = nullptr, *RHS = nullptr; | |||
1108 | SelectPatternFlavor SPF = matchSelectPattern(I, LHS, RHS).Flavor; | |||
1109 | if (SelectPatternResult::isMinOrMax(SPF)) { | |||
1110 | computeKnownBits(RHS, Known, Depth + 1, Q); | |||
1111 | computeKnownBits(LHS, Known2, Depth + 1, Q); | |||
1112 | switch (SPF) { | |||
1113 | default: | |||
1114 | llvm_unreachable("Unhandled select pattern flavor!")::llvm::llvm_unreachable_internal("Unhandled select pattern flavor!" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1114); | |||
1115 | case SPF_SMAX: | |||
1116 | Known = KnownBits::smax(Known, Known2); | |||
1117 | break; | |||
1118 | case SPF_SMIN: | |||
1119 | Known = KnownBits::smin(Known, Known2); | |||
1120 | break; | |||
1121 | case SPF_UMAX: | |||
1122 | Known = KnownBits::umax(Known, Known2); | |||
1123 | break; | |||
1124 | case SPF_UMIN: | |||
1125 | Known = KnownBits::umin(Known, Known2); | |||
1126 | break; | |||
1127 | } | |||
1128 | break; | |||
1129 | } | |||
1130 | ||||
1131 | computeKnownBits(I->getOperand(2), Known, Depth + 1, Q); | |||
1132 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1133 | ||||
1134 | // Only known if known in both the LHS and RHS. | |||
1135 | Known = KnownBits::commonBits(Known, Known2); | |||
1136 | ||||
1137 | if (SPF == SPF_ABS) { | |||
1138 | // RHS from matchSelectPattern returns the negation part of abs pattern. | |||
1139 | // If the negate has an NSW flag we can assume the sign bit of the result | |||
1140 | // will be 0 because that makes abs(INT_MIN) undefined. | |||
1141 | if (match(RHS, m_Neg(m_Specific(LHS))) && | |||
1142 | Q.IIQ.hasNoSignedWrap(cast<Instruction>(RHS))) | |||
1143 | Known.Zero.setSignBit(); | |||
1144 | } | |||
1145 | ||||
1146 | break; | |||
1147 | } | |||
1148 | case Instruction::FPTrunc: | |||
1149 | case Instruction::FPExt: | |||
1150 | case Instruction::FPToUI: | |||
1151 | case Instruction::FPToSI: | |||
1152 | case Instruction::SIToFP: | |||
1153 | case Instruction::UIToFP: | |||
1154 | break; // Can't work with floating point. | |||
1155 | case Instruction::PtrToInt: | |||
1156 | case Instruction::IntToPtr: | |||
1157 | // Fall through and handle them the same as zext/trunc. | |||
1158 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
1159 | case Instruction::ZExt: | |||
1160 | case Instruction::Trunc: { | |||
1161 | Type *SrcTy = I->getOperand(0)->getType(); | |||
1162 | ||||
1163 | unsigned SrcBitWidth; | |||
1164 | // Note that we handle pointer operands here because of inttoptr/ptrtoint | |||
1165 | // which fall through here. | |||
1166 | Type *ScalarTy = SrcTy->getScalarType(); | |||
1167 | SrcBitWidth = ScalarTy->isPointerTy() ? | |||
1168 | Q.DL.getPointerTypeSizeInBits(ScalarTy) : | |||
1169 | Q.DL.getTypeSizeInBits(ScalarTy); | |||
1170 | ||||
1171 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1171, __extension__ __PRETTY_FUNCTION__)); | |||
1172 | Known = Known.anyextOrTrunc(SrcBitWidth); | |||
1173 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1174 | Known = Known.zextOrTrunc(BitWidth); | |||
1175 | break; | |||
1176 | } | |||
1177 | case Instruction::BitCast: { | |||
1178 | Type *SrcTy = I->getOperand(0)->getType(); | |||
1179 | if (SrcTy->isIntOrPtrTy() && | |||
1180 | // TODO: For now, not handling conversions like: | |||
1181 | // (bitcast i64 %x to <2 x i32>) | |||
1182 | !I->getType()->isVectorTy()) { | |||
1183 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1184 | break; | |||
1185 | } | |||
1186 | ||||
1187 | // Handle cast from vector integer type to scalar or vector integer. | |||
1188 | auto *SrcVecTy = dyn_cast<FixedVectorType>(SrcTy); | |||
1189 | if (!SrcVecTy || !SrcVecTy->getElementType()->isIntegerTy() || | |||
1190 | !I->getType()->isIntOrIntVectorTy()) | |||
1191 | break; | |||
1192 | ||||
1193 | // Look through a cast from narrow vector elements to wider type. | |||
1194 | // Examples: v4i32 -> v2i64, v3i8 -> v24 | |||
1195 | unsigned SubBitWidth = SrcVecTy->getScalarSizeInBits(); | |||
1196 | if (BitWidth % SubBitWidth == 0) { | |||
1197 | // Known bits are automatically intersected across demanded elements of a | |||
1198 | // vector. So for example, if a bit is computed as known zero, it must be | |||
1199 | // zero across all demanded elements of the vector. | |||
1200 | // | |||
1201 | // For this bitcast, each demanded element of the output is sub-divided | |||
1202 | // across a set of smaller vector elements in the source vector. To get | |||
1203 | // the known bits for an entire element of the output, compute the known | |||
1204 | // bits for each sub-element sequentially. This is done by shifting the | |||
1205 | // one-set-bit demanded elements parameter across the sub-elements for | |||
1206 | // consecutive calls to computeKnownBits. We are using the demanded | |||
1207 | // elements parameter as a mask operator. | |||
1208 | // | |||
1209 | // The known bits of each sub-element are then inserted into place | |||
1210 | // (dependent on endian) to form the full result of known bits. | |||
1211 | unsigned NumElts = DemandedElts.getBitWidth(); | |||
1212 | unsigned SubScale = BitWidth / SubBitWidth; | |||
1213 | APInt SubDemandedElts = APInt::getNullValue(NumElts * SubScale); | |||
1214 | for (unsigned i = 0; i != NumElts; ++i) { | |||
1215 | if (DemandedElts[i]) | |||
1216 | SubDemandedElts.setBit(i * SubScale); | |||
1217 | } | |||
1218 | ||||
1219 | KnownBits KnownSrc(SubBitWidth); | |||
1220 | for (unsigned i = 0; i != SubScale; ++i) { | |||
1221 | computeKnownBits(I->getOperand(0), SubDemandedElts.shl(i), KnownSrc, | |||
1222 | Depth + 1, Q); | |||
1223 | unsigned ShiftElt = Q.DL.isLittleEndian() ? i : SubScale - 1 - i; | |||
1224 | Known.insertBits(KnownSrc, ShiftElt * SubBitWidth); | |||
1225 | } | |||
1226 | } | |||
1227 | break; | |||
1228 | } | |||
1229 | case Instruction::SExt: { | |||
1230 | // Compute the bits in the result that are not present in the input. | |||
1231 | unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits(); | |||
1232 | ||||
1233 | Known = Known.trunc(SrcBitWidth); | |||
1234 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1235 | // If the sign bit of the input is known set or clear, then we know the | |||
1236 | // top bits of the result. | |||
1237 | Known = Known.sext(BitWidth); | |||
1238 | break; | |||
1239 | } | |||
1240 | case Instruction::Shl: { | |||
1241 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1242 | auto KF = [NSW](const KnownBits &KnownVal, const KnownBits &KnownAmt) { | |||
1243 | KnownBits Result = KnownBits::shl(KnownVal, KnownAmt); | |||
1244 | // If this shift has "nsw" keyword, then the result is either a poison | |||
1245 | // value or has the same sign bit as the first operand. | |||
1246 | if (NSW) { | |||
1247 | if (KnownVal.Zero.isSignBitSet()) | |||
1248 | Result.Zero.setSignBit(); | |||
1249 | if (KnownVal.One.isSignBitSet()) | |||
1250 | Result.One.setSignBit(); | |||
1251 | } | |||
1252 | return Result; | |||
1253 | }; | |||
1254 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, | |||
1255 | KF); | |||
1256 | // Trailing zeros of a right-shifted constant never decrease. | |||
1257 | const APInt *C; | |||
1258 | if (match(I->getOperand(0), m_APInt(C))) | |||
1259 | Known.Zero.setLowBits(C->countTrailingZeros()); | |||
1260 | break; | |||
1261 | } | |||
1262 | case Instruction::LShr: { | |||
1263 | auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) { | |||
1264 | return KnownBits::lshr(KnownVal, KnownAmt); | |||
1265 | }; | |||
1266 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, | |||
1267 | KF); | |||
1268 | // Leading zeros of a left-shifted constant never decrease. | |||
1269 | const APInt *C; | |||
1270 | if (match(I->getOperand(0), m_APInt(C))) | |||
1271 | Known.Zero.setHighBits(C->countLeadingZeros()); | |||
1272 | break; | |||
1273 | } | |||
1274 | case Instruction::AShr: { | |||
1275 | auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) { | |||
1276 | return KnownBits::ashr(KnownVal, KnownAmt); | |||
1277 | }; | |||
1278 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, | |||
1279 | KF); | |||
1280 | break; | |||
1281 | } | |||
1282 | case Instruction::Sub: { | |||
1283 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1284 | computeKnownBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW, | |||
1285 | DemandedElts, Known, Known2, Depth, Q); | |||
1286 | break; | |||
1287 | } | |||
1288 | case Instruction::Add: { | |||
1289 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1290 | computeKnownBitsAddSub(true, I->getOperand(0), I->getOperand(1), NSW, | |||
1291 | DemandedElts, Known, Known2, Depth, Q); | |||
1292 | break; | |||
1293 | } | |||
1294 | case Instruction::SRem: | |||
1295 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1296 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1297 | Known = KnownBits::srem(Known, Known2); | |||
1298 | break; | |||
1299 | ||||
1300 | case Instruction::URem: | |||
1301 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1302 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1303 | Known = KnownBits::urem(Known, Known2); | |||
1304 | break; | |||
1305 | case Instruction::Alloca: | |||
1306 | Known.Zero.setLowBits(Log2(cast<AllocaInst>(I)->getAlign())); | |||
1307 | break; | |||
1308 | case Instruction::GetElementPtr: { | |||
1309 | // Analyze all of the subscripts of this getelementptr instruction | |||
1310 | // to determine if we can prove known low zero bits. | |||
1311 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1312 | // Accumulate the constant indices in a separate variable | |||
1313 | // to minimize the number of calls to computeForAddSub. | |||
1314 | APInt AccConstIndices(BitWidth, 0, /*IsSigned*/ true); | |||
1315 | ||||
1316 | gep_type_iterator GTI = gep_type_begin(I); | |||
1317 | for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) { | |||
1318 | // TrailZ can only become smaller, short-circuit if we hit zero. | |||
1319 | if (Known.isUnknown()) | |||
1320 | break; | |||
1321 | ||||
1322 | Value *Index = I->getOperand(i); | |||
1323 | ||||
1324 | // Handle case when index is zero. | |||
1325 | Constant *CIndex = dyn_cast<Constant>(Index); | |||
1326 | if (CIndex && CIndex->isZeroValue()) | |||
1327 | continue; | |||
1328 | ||||
1329 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
1330 | // Handle struct member offset arithmetic. | |||
1331 | ||||
1332 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1333, __extension__ __PRETTY_FUNCTION__)) | |||
1333 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1333, __extension__ __PRETTY_FUNCTION__)); | |||
1334 | ||||
1335 | if (CIndex->getType()->isVectorTy()) | |||
1336 | Index = CIndex->getSplatValue(); | |||
1337 | ||||
1338 | unsigned Idx = cast<ConstantInt>(Index)->getZExtValue(); | |||
1339 | const StructLayout *SL = Q.DL.getStructLayout(STy); | |||
1340 | uint64_t Offset = SL->getElementOffset(Idx); | |||
1341 | AccConstIndices += Offset; | |||
1342 | continue; | |||
1343 | } | |||
1344 | ||||
1345 | // Handle array index arithmetic. | |||
1346 | Type *IndexedTy = GTI.getIndexedType(); | |||
1347 | if (!IndexedTy->isSized()) { | |||
1348 | Known.resetAll(); | |||
1349 | break; | |||
1350 | } | |||
1351 | ||||
1352 | unsigned IndexBitWidth = Index->getType()->getScalarSizeInBits(); | |||
1353 | KnownBits IndexBits(IndexBitWidth); | |||
1354 | computeKnownBits(Index, IndexBits, Depth + 1, Q); | |||
1355 | TypeSize IndexTypeSize = Q.DL.getTypeAllocSize(IndexedTy); | |||
1356 | uint64_t TypeSizeInBytes = IndexTypeSize.getKnownMinSize(); | |||
1357 | KnownBits ScalingFactor(IndexBitWidth); | |||
1358 | // Multiply by current sizeof type. | |||
1359 | // &A[i] == A + i * sizeof(*A[i]). | |||
1360 | if (IndexTypeSize.isScalable()) { | |||
1361 | // For scalable types the only thing we know about sizeof is | |||
1362 | // that this is a multiple of the minimum size. | |||
1363 | ScalingFactor.Zero.setLowBits(countTrailingZeros(TypeSizeInBytes)); | |||
1364 | } else if (IndexBits.isConstant()) { | |||
1365 | APInt IndexConst = IndexBits.getConstant(); | |||
1366 | APInt ScalingFactor(IndexBitWidth, TypeSizeInBytes); | |||
1367 | IndexConst *= ScalingFactor; | |||
1368 | AccConstIndices += IndexConst.sextOrTrunc(BitWidth); | |||
1369 | continue; | |||
1370 | } else { | |||
1371 | ScalingFactor = | |||
1372 | KnownBits::makeConstant(APInt(IndexBitWidth, TypeSizeInBytes)); | |||
1373 | } | |||
1374 | IndexBits = KnownBits::mul(IndexBits, ScalingFactor); | |||
1375 | ||||
1376 | // If the offsets have a different width from the pointer, according | |||
1377 | // to the language reference we need to sign-extend or truncate them | |||
1378 | // to the width of the pointer. | |||
1379 | IndexBits = IndexBits.sextOrTrunc(BitWidth); | |||
1380 | ||||
1381 | // Note that inbounds does *not* guarantee nsw for the addition, as only | |||
1382 | // the offset is signed, while the base address is unsigned. | |||
1383 | Known = KnownBits::computeForAddSub( | |||
1384 | /*Add=*/true, /*NSW=*/false, Known, IndexBits); | |||
1385 | } | |||
1386 | if (!Known.isUnknown() && !AccConstIndices.isNullValue()) { | |||
1387 | KnownBits Index = KnownBits::makeConstant(AccConstIndices); | |||
1388 | Known = KnownBits::computeForAddSub( | |||
1389 | /*Add=*/true, /*NSW=*/false, Known, Index); | |||
1390 | } | |||
1391 | break; | |||
1392 | } | |||
1393 | case Instruction::PHI: { | |||
1394 | const PHINode *P = cast<PHINode>(I); | |||
1395 | BinaryOperator *BO = nullptr; | |||
1396 | Value *R = nullptr, *L = nullptr; | |||
1397 | if (matchSimpleRecurrence(P, BO, R, L)) { | |||
1398 | // Handle the case of a simple two-predecessor recurrence PHI. | |||
1399 | // There's a lot more that could theoretically be done here, but | |||
1400 | // this is sufficient to catch some interesting cases. | |||
1401 | unsigned Opcode = BO->getOpcode(); | |||
1402 | ||||
1403 | // If this is a shift recurrence, we know the bits being shifted in. | |||
1404 | // We can combine that with information about the start value of the | |||
1405 | // recurrence to conclude facts about the result. | |||
1406 | if ((Opcode == Instruction::LShr || Opcode == Instruction::AShr || | |||
1407 | Opcode == Instruction::Shl) && | |||
1408 | BO->getOperand(0) == I) { | |||
1409 | ||||
1410 | // We have matched a recurrence of the form: | |||
1411 | // %iv = [R, %entry], [%iv.next, %backedge] | |||
1412 | // %iv.next = shift_op %iv, L | |||
1413 | ||||
1414 | // Recurse with the phi context to avoid concern about whether facts | |||
1415 | // inferred hold at original context instruction. TODO: It may be | |||
1416 | // correct to use the original context. IF warranted, explore and | |||
1417 | // add sufficient tests to cover. | |||
1418 | Query RecQ = Q; | |||
1419 | RecQ.CxtI = P; | |||
1420 | computeKnownBits(R, DemandedElts, Known2, Depth + 1, RecQ); | |||
1421 | switch (Opcode) { | |||
1422 | case Instruction::Shl: | |||
1423 | // A shl recurrence will only increase the tailing zeros | |||
1424 | Known.Zero.setLowBits(Known2.countMinTrailingZeros()); | |||
1425 | break; | |||
1426 | case Instruction::LShr: | |||
1427 | // A lshr recurrence will preserve the leading zeros of the | |||
1428 | // start value | |||
1429 | Known.Zero.setHighBits(Known2.countMinLeadingZeros()); | |||
1430 | break; | |||
1431 | case Instruction::AShr: | |||
1432 | // An ashr recurrence will extend the initial sign bit | |||
1433 | Known.Zero.setHighBits(Known2.countMinLeadingZeros()); | |||
1434 | Known.One.setHighBits(Known2.countMinLeadingOnes()); | |||
1435 | break; | |||
1436 | }; | |||
1437 | } | |||
1438 | ||||
1439 | // Check for operations that have the property that if | |||
1440 | // both their operands have low zero bits, the result | |||
1441 | // will have low zero bits. | |||
1442 | if (Opcode == Instruction::Add || | |||
1443 | Opcode == Instruction::Sub || | |||
1444 | Opcode == Instruction::And || | |||
1445 | Opcode == Instruction::Or || | |||
1446 | Opcode == Instruction::Mul) { | |||
1447 | // Change the context instruction to the "edge" that flows into the | |||
1448 | // phi. This is important because that is where the value is actually | |||
1449 | // "evaluated" even though it is used later somewhere else. (see also | |||
1450 | // D69571). | |||
1451 | Query RecQ = Q; | |||
1452 | ||||
1453 | unsigned OpNum = P->getOperand(0) == R ? 0 : 1; | |||
1454 | Instruction *RInst = P->getIncomingBlock(OpNum)->getTerminator(); | |||
1455 | Instruction *LInst = P->getIncomingBlock(1-OpNum)->getTerminator(); | |||
1456 | ||||
1457 | // Ok, we have a PHI of the form L op= R. Check for low | |||
1458 | // zero bits. | |||
1459 | RecQ.CxtI = RInst; | |||
1460 | computeKnownBits(R, Known2, Depth + 1, RecQ); | |||
1461 | ||||
1462 | // We need to take the minimum number of known bits | |||
1463 | KnownBits Known3(BitWidth); | |||
1464 | RecQ.CxtI = LInst; | |||
1465 | computeKnownBits(L, Known3, Depth + 1, RecQ); | |||
1466 | ||||
1467 | Known.Zero.setLowBits(std::min(Known2.countMinTrailingZeros(), | |||
1468 | Known3.countMinTrailingZeros())); | |||
1469 | ||||
1470 | auto *OverflowOp = dyn_cast<OverflowingBinaryOperator>(BO); | |||
1471 | if (OverflowOp && Q.IIQ.hasNoSignedWrap(OverflowOp)) { | |||
1472 | // If initial value of recurrence is nonnegative, and we are adding | |||
1473 | // a nonnegative number with nsw, the result can only be nonnegative | |||
1474 | // or poison value regardless of the number of times we execute the | |||
1475 | // add in phi recurrence. If initial value is negative and we are | |||
1476 | // adding a negative number with nsw, the result can only be | |||
1477 | // negative or poison value. Similar arguments apply to sub and mul. | |||
1478 | // | |||
1479 | // (add non-negative, non-negative) --> non-negative | |||
1480 | // (add negative, negative) --> negative | |||
1481 | if (Opcode == Instruction::Add) { | |||
1482 | if (Known2.isNonNegative() && Known3.isNonNegative()) | |||
1483 | Known.makeNonNegative(); | |||
1484 | else if (Known2.isNegative() && Known3.isNegative()) | |||
1485 | Known.makeNegative(); | |||
1486 | } | |||
1487 | ||||
1488 | // (sub nsw non-negative, negative) --> non-negative | |||
1489 | // (sub nsw negative, non-negative) --> negative | |||
1490 | else if (Opcode == Instruction::Sub && BO->getOperand(0) == I) { | |||
1491 | if (Known2.isNonNegative() && Known3.isNegative()) | |||
1492 | Known.makeNonNegative(); | |||
1493 | else if (Known2.isNegative() && Known3.isNonNegative()) | |||
1494 | Known.makeNegative(); | |||
1495 | } | |||
1496 | ||||
1497 | // (mul nsw non-negative, non-negative) --> non-negative | |||
1498 | else if (Opcode == Instruction::Mul && Known2.isNonNegative() && | |||
1499 | Known3.isNonNegative()) | |||
1500 | Known.makeNonNegative(); | |||
1501 | } | |||
1502 | ||||
1503 | break; | |||
1504 | } | |||
1505 | } | |||
1506 | ||||
1507 | // Unreachable blocks may have zero-operand PHI nodes. | |||
1508 | if (P->getNumIncomingValues() == 0) | |||
1509 | break; | |||
1510 | ||||
1511 | // Otherwise take the unions of the known bit sets of the operands, | |||
1512 | // taking conservative care to avoid excessive recursion. | |||
1513 | if (Depth < MaxAnalysisRecursionDepth - 1 && !Known.Zero && !Known.One) { | |||
1514 | // Skip if every incoming value references to ourself. | |||
1515 | if (dyn_cast_or_null<UndefValue>(P->hasConstantValue())) | |||
1516 | break; | |||
1517 | ||||
1518 | Known.Zero.setAllBits(); | |||
1519 | Known.One.setAllBits(); | |||
1520 | for (unsigned u = 0, e = P->getNumIncomingValues(); u < e; ++u) { | |||
1521 | Value *IncValue = P->getIncomingValue(u); | |||
1522 | // Skip direct self references. | |||
1523 | if (IncValue == P) continue; | |||
1524 | ||||
1525 | // Change the context instruction to the "edge" that flows into the | |||
1526 | // phi. This is important because that is where the value is actually | |||
1527 | // "evaluated" even though it is used later somewhere else. (see also | |||
1528 | // D69571). | |||
1529 | Query RecQ = Q; | |||
1530 | RecQ.CxtI = P->getIncomingBlock(u)->getTerminator(); | |||
1531 | ||||
1532 | Known2 = KnownBits(BitWidth); | |||
1533 | // Recurse, but cap the recursion to one level, because we don't | |||
1534 | // want to waste time spinning around in loops. | |||
1535 | computeKnownBits(IncValue, Known2, MaxAnalysisRecursionDepth - 1, RecQ); | |||
1536 | Known = KnownBits::commonBits(Known, Known2); | |||
1537 | // If all bits have been ruled out, there's no need to check | |||
1538 | // more operands. | |||
1539 | if (Known.isUnknown()) | |||
1540 | break; | |||
1541 | } | |||
1542 | } | |||
1543 | break; | |||
1544 | } | |||
1545 | case Instruction::Call: | |||
1546 | case Instruction::Invoke: | |||
1547 | // If range metadata is attached to this call, set known bits from that, | |||
1548 | // and then intersect with known bits based on other properties of the | |||
1549 | // function. | |||
1550 | if (MDNode *MD = | |||
1551 | Q.IIQ.getMetadata(cast<Instruction>(I), LLVMContext::MD_range)) | |||
1552 | computeKnownBitsFromRangeMetadata(*MD, Known); | |||
1553 | if (const Value *RV = cast<CallBase>(I)->getReturnedArgOperand()) { | |||
1554 | computeKnownBits(RV, Known2, Depth + 1, Q); | |||
1555 | Known.Zero |= Known2.Zero; | |||
1556 | Known.One |= Known2.One; | |||
1557 | } | |||
1558 | if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { | |||
1559 | switch (II->getIntrinsicID()) { | |||
1560 | default: break; | |||
1561 | case Intrinsic::abs: { | |||
1562 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1563 | bool IntMinIsPoison = match(II->getArgOperand(1), m_One()); | |||
1564 | Known = Known2.abs(IntMinIsPoison); | |||
1565 | break; | |||
1566 | } | |||
1567 | case Intrinsic::bitreverse: | |||
1568 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1569 | Known.Zero |= Known2.Zero.reverseBits(); | |||
1570 | Known.One |= Known2.One.reverseBits(); | |||
1571 | break; | |||
1572 | case Intrinsic::bswap: | |||
1573 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); | |||
1574 | Known.Zero |= Known2.Zero.byteSwap(); | |||
1575 | Known.One |= Known2.One.byteSwap(); | |||
1576 | break; | |||
1577 | case Intrinsic::ctlz: { | |||
1578 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1579 | // If we have a known 1, its position is our upper bound. | |||
1580 | unsigned PossibleLZ = Known2.countMaxLeadingZeros(); | |||
1581 | // If this call is undefined for 0, the result will be less than 2^n. | |||
1582 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) | |||
1583 | PossibleLZ = std::min(PossibleLZ, BitWidth - 1); | |||
1584 | unsigned LowBits = Log2_32(PossibleLZ)+1; | |||
1585 | Known.Zero.setBitsFrom(LowBits); | |||
1586 | break; | |||
1587 | } | |||
1588 | case Intrinsic::cttz: { | |||
1589 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1590 | // If we have a known 1, its position is our upper bound. | |||
1591 | unsigned PossibleTZ = Known2.countMaxTrailingZeros(); | |||
1592 | // If this call is undefined for 0, the result will be less than 2^n. | |||
1593 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) | |||
1594 | PossibleTZ = std::min(PossibleTZ, BitWidth - 1); | |||
1595 | unsigned LowBits = Log2_32(PossibleTZ)+1; | |||
1596 | Known.Zero.setBitsFrom(LowBits); | |||
1597 | break; | |||
1598 | } | |||
1599 | case Intrinsic::ctpop: { | |||
1600 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1601 | // We can bound the space the count needs. Also, bits known to be zero | |||
1602 | // can't contribute to the population. | |||
1603 | unsigned BitsPossiblySet = Known2.countMaxPopulation(); | |||
1604 | unsigned LowBits = Log2_32(BitsPossiblySet)+1; | |||
1605 | Known.Zero.setBitsFrom(LowBits); | |||
1606 | // TODO: we could bound KnownOne using the lower bound on the number | |||
1607 | // of bits which might be set provided by popcnt KnownOne2. | |||
1608 | break; | |||
1609 | } | |||
1610 | case Intrinsic::fshr: | |||
1611 | case Intrinsic::fshl: { | |||
1612 | const APInt *SA; | |||
1613 | if (!match(I->getOperand(2), m_APInt(SA))) | |||
1614 | break; | |||
1615 | ||||
1616 | // Normalize to funnel shift left. | |||
1617 | uint64_t ShiftAmt = SA->urem(BitWidth); | |||
1618 | if (II->getIntrinsicID() == Intrinsic::fshr) | |||
1619 | ShiftAmt = BitWidth - ShiftAmt; | |||
1620 | ||||
1621 | KnownBits Known3(BitWidth); | |||
1622 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1623 | computeKnownBits(I->getOperand(1), Known3, Depth + 1, Q); | |||
1624 | ||||
1625 | Known.Zero = | |||
1626 | Known2.Zero.shl(ShiftAmt) | Known3.Zero.lshr(BitWidth - ShiftAmt); | |||
1627 | Known.One = | |||
1628 | Known2.One.shl(ShiftAmt) | Known3.One.lshr(BitWidth - ShiftAmt); | |||
1629 | break; | |||
1630 | } | |||
1631 | case Intrinsic::uadd_sat: | |||
1632 | case Intrinsic::usub_sat: { | |||
1633 | bool IsAdd = II->getIntrinsicID() == Intrinsic::uadd_sat; | |||
1634 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1635 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1636 | ||||
1637 | // Add: Leading ones of either operand are preserved. | |||
1638 | // Sub: Leading zeros of LHS and leading ones of RHS are preserved | |||
1639 | // as leading zeros in the result. | |||
1640 | unsigned LeadingKnown; | |||
1641 | if (IsAdd) | |||
1642 | LeadingKnown = std::max(Known.countMinLeadingOnes(), | |||
1643 | Known2.countMinLeadingOnes()); | |||
1644 | else | |||
1645 | LeadingKnown = std::max(Known.countMinLeadingZeros(), | |||
1646 | Known2.countMinLeadingOnes()); | |||
1647 | ||||
1648 | Known = KnownBits::computeForAddSub( | |||
1649 | IsAdd, /* NSW */ false, Known, Known2); | |||
1650 | ||||
1651 | // We select between the operation result and all-ones/zero | |||
1652 | // respectively, so we can preserve known ones/zeros. | |||
1653 | if (IsAdd) { | |||
1654 | Known.One.setHighBits(LeadingKnown); | |||
1655 | Known.Zero.clearAllBits(); | |||
1656 | } else { | |||
1657 | Known.Zero.setHighBits(LeadingKnown); | |||
1658 | Known.One.clearAllBits(); | |||
1659 | } | |||
1660 | break; | |||
1661 | } | |||
1662 | case Intrinsic::umin: | |||
1663 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1664 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1665 | Known = KnownBits::umin(Known, Known2); | |||
1666 | break; | |||
1667 | case Intrinsic::umax: | |||
1668 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1669 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1670 | Known = KnownBits::umax(Known, Known2); | |||
1671 | break; | |||
1672 | case Intrinsic::smin: | |||
1673 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1674 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1675 | Known = KnownBits::smin(Known, Known2); | |||
1676 | break; | |||
1677 | case Intrinsic::smax: | |||
1678 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1679 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1680 | Known = KnownBits::smax(Known, Known2); | |||
1681 | break; | |||
1682 | case Intrinsic::x86_sse42_crc32_64_64: | |||
1683 | Known.Zero.setBitsFrom(32); | |||
1684 | break; | |||
1685 | case Intrinsic::riscv_vsetvli: | |||
1686 | case Intrinsic::riscv_vsetvlimax: | |||
1687 | // Assume that VL output is positive and would fit in an int32_t. | |||
1688 | // TODO: VLEN might be capped at 16 bits in a future V spec update. | |||
1689 | if (BitWidth >= 32) | |||
1690 | Known.Zero.setBitsFrom(31); | |||
1691 | break; | |||
1692 | } | |||
1693 | } | |||
1694 | break; | |||
1695 | case Instruction::ShuffleVector: { | |||
1696 | auto *Shuf = dyn_cast<ShuffleVectorInst>(I); | |||
1697 | // FIXME: Do we need to handle ConstantExpr involving shufflevectors? | |||
1698 | if (!Shuf) { | |||
1699 | Known.resetAll(); | |||
1700 | return; | |||
1701 | } | |||
1702 | // For undef elements, we don't know anything about the common state of | |||
1703 | // the shuffle result. | |||
1704 | APInt DemandedLHS, DemandedRHS; | |||
1705 | if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) { | |||
1706 | Known.resetAll(); | |||
1707 | return; | |||
1708 | } | |||
1709 | Known.One.setAllBits(); | |||
1710 | Known.Zero.setAllBits(); | |||
1711 | if (!!DemandedLHS) { | |||
1712 | const Value *LHS = Shuf->getOperand(0); | |||
1713 | computeKnownBits(LHS, DemandedLHS, Known, Depth + 1, Q); | |||
1714 | // If we don't know any bits, early out. | |||
1715 | if (Known.isUnknown()) | |||
1716 | break; | |||
1717 | } | |||
1718 | if (!!DemandedRHS) { | |||
1719 | const Value *RHS = Shuf->getOperand(1); | |||
1720 | computeKnownBits(RHS, DemandedRHS, Known2, Depth + 1, Q); | |||
1721 | Known = KnownBits::commonBits(Known, Known2); | |||
1722 | } | |||
1723 | break; | |||
1724 | } | |||
1725 | case Instruction::InsertElement: { | |||
1726 | const Value *Vec = I->getOperand(0); | |||
1727 | const Value *Elt = I->getOperand(1); | |||
1728 | auto *CIdx = dyn_cast<ConstantInt>(I->getOperand(2)); | |||
1729 | // Early out if the index is non-constant or out-of-range. | |||
1730 | unsigned NumElts = DemandedElts.getBitWidth(); | |||
1731 | if (!CIdx || CIdx->getValue().uge(NumElts)) { | |||
1732 | Known.resetAll(); | |||
1733 | return; | |||
1734 | } | |||
1735 | Known.One.setAllBits(); | |||
1736 | Known.Zero.setAllBits(); | |||
1737 | unsigned EltIdx = CIdx->getZExtValue(); | |||
1738 | // Do we demand the inserted element? | |||
1739 | if (DemandedElts[EltIdx]) { | |||
1740 | computeKnownBits(Elt, Known, Depth + 1, Q); | |||
1741 | // If we don't know any bits, early out. | |||
1742 | if (Known.isUnknown()) | |||
1743 | break; | |||
1744 | } | |||
1745 | // We don't need the base vector element that has been inserted. | |||
1746 | APInt DemandedVecElts = DemandedElts; | |||
1747 | DemandedVecElts.clearBit(EltIdx); | |||
1748 | if (!!DemandedVecElts) { | |||
1749 | computeKnownBits(Vec, DemandedVecElts, Known2, Depth + 1, Q); | |||
1750 | Known = KnownBits::commonBits(Known, Known2); | |||
1751 | } | |||
1752 | break; | |||
1753 | } | |||
1754 | case Instruction::ExtractElement: { | |||
1755 | // Look through extract element. If the index is non-constant or | |||
1756 | // out-of-range demand all elements, otherwise just the extracted element. | |||
1757 | const Value *Vec = I->getOperand(0); | |||
1758 | const Value *Idx = I->getOperand(1); | |||
1759 | auto *CIdx = dyn_cast<ConstantInt>(Idx); | |||
1760 | if (isa<ScalableVectorType>(Vec->getType())) { | |||
1761 | // FIXME: there's probably *something* we can do with scalable vectors | |||
1762 | Known.resetAll(); | |||
1763 | break; | |||
1764 | } | |||
1765 | unsigned NumElts = cast<FixedVectorType>(Vec->getType())->getNumElements(); | |||
1766 | APInt DemandedVecElts = APInt::getAllOnesValue(NumElts); | |||
1767 | if (CIdx && CIdx->getValue().ult(NumElts)) | |||
1768 | DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue()); | |||
1769 | computeKnownBits(Vec, DemandedVecElts, Known, Depth + 1, Q); | |||
1770 | break; | |||
1771 | } | |||
1772 | case Instruction::ExtractValue: | |||
1773 | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I->getOperand(0))) { | |||
1774 | const ExtractValueInst *EVI = cast<ExtractValueInst>(I); | |||
1775 | if (EVI->getNumIndices() != 1) break; | |||
1776 | if (EVI->getIndices()[0] == 0) { | |||
1777 | switch (II->getIntrinsicID()) { | |||
1778 | default: break; | |||
1779 | case Intrinsic::uadd_with_overflow: | |||
1780 | case Intrinsic::sadd_with_overflow: | |||
1781 | computeKnownBitsAddSub(true, II->getArgOperand(0), | |||
1782 | II->getArgOperand(1), false, DemandedElts, | |||
1783 | Known, Known2, Depth, Q); | |||
1784 | break; | |||
1785 | case Intrinsic::usub_with_overflow: | |||
1786 | case Intrinsic::ssub_with_overflow: | |||
1787 | computeKnownBitsAddSub(false, II->getArgOperand(0), | |||
1788 | II->getArgOperand(1), false, DemandedElts, | |||
1789 | Known, Known2, Depth, Q); | |||
1790 | break; | |||
1791 | case Intrinsic::umul_with_overflow: | |||
1792 | case Intrinsic::smul_with_overflow: | |||
1793 | computeKnownBitsMul(II->getArgOperand(0), II->getArgOperand(1), false, | |||
1794 | DemandedElts, Known, Known2, Depth, Q); | |||
1795 | break; | |||
1796 | } | |||
1797 | } | |||
1798 | } | |||
1799 | break; | |||
1800 | case Instruction::Freeze: | |||
1801 | if (isGuaranteedNotToBePoison(I->getOperand(0), Q.AC, Q.CxtI, Q.DT, | |||
1802 | Depth + 1)) | |||
1803 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1804 | break; | |||
1805 | } | |||
1806 | } | |||
1807 | ||||
1808 | /// Determine which bits of V are known to be either zero or one and return | |||
1809 | /// them. | |||
1810 | KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
1811 | unsigned Depth, const Query &Q) { | |||
1812 | KnownBits Known(getBitWidth(V->getType(), Q.DL)); | |||
1813 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
1814 | return Known; | |||
1815 | } | |||
1816 | ||||
1817 | /// Determine which bits of V are known to be either zero or one and return | |||
1818 | /// them. | |||
1819 | KnownBits computeKnownBits(const Value *V, unsigned Depth, const Query &Q) { | |||
1820 | KnownBits Known(getBitWidth(V->getType(), Q.DL)); | |||
1821 | computeKnownBits(V, Known, Depth, Q); | |||
1822 | return Known; | |||
1823 | } | |||
1824 | ||||
1825 | /// Determine which bits of V are known to be either zero or one and return | |||
1826 | /// them in the Known bit set. | |||
1827 | /// | |||
1828 | /// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that | |||
1829 | /// we cannot optimize based on the assumption that it is zero without changing | |||
1830 | /// it to be an explicit zero. If we don't change it to zero, other code could | |||
1831 | /// optimized based on the contradictory assumption that it is non-zero. | |||
1832 | /// Because instcombine aggressively folds operations with undef args anyway, | |||
1833 | /// this won't lose us code quality. | |||
1834 | /// | |||
1835 | /// This function is defined on values with integer type, values with pointer | |||
1836 | /// type, and vectors of integers. In the case | |||
1837 | /// where V is a vector, known zero, and known one values are the | |||
1838 | /// same width as the vector element, and the bit is set only if it is true | |||
1839 | /// for all of the demanded elements in the vector specified by DemandedElts. | |||
1840 | void computeKnownBits(const Value *V, const APInt &DemandedElts, | |||
1841 | KnownBits &Known, unsigned Depth, const Query &Q) { | |||
1842 | if (!DemandedElts || isa<ScalableVectorType>(V->getType())) { | |||
1843 | // No demanded elts or V is a scalable vector, better to assume we don't | |||
1844 | // know anything. | |||
1845 | Known.resetAll(); | |||
1846 | return; | |||
1847 | } | |||
1848 | ||||
1849 | assert(V && "No Value?")(static_cast <bool> (V && "No Value?") ? void ( 0) : __assert_fail ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1849, __extension__ __PRETTY_FUNCTION__)); | |||
1850 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1850, __extension__ __PRETTY_FUNCTION__)); | |||
1851 | ||||
1852 | #ifndef NDEBUG | |||
1853 | Type *Ty = V->getType(); | |||
1854 | unsigned BitWidth = Known.getBitWidth(); | |||
1855 | ||||
1856 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1857, __extension__ __PRETTY_FUNCTION__)) | |||
1857 | "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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1857, __extension__ __PRETTY_FUNCTION__)); | |||
1858 | ||||
1859 | if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) { | |||
1860 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1862, __extension__ __PRETTY_FUNCTION__)) | |||
1861 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1862, __extension__ __PRETTY_FUNCTION__)) | |||
1862 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1862, __extension__ __PRETTY_FUNCTION__)); | |||
1863 | } else { | |||
1864 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1865, __extension__ __PRETTY_FUNCTION__)) | |||
1865 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1865, __extension__ __PRETTY_FUNCTION__)); | |||
1866 | } | |||
1867 | ||||
1868 | Type *ScalarTy = Ty->getScalarType(); | |||
1869 | if (ScalarTy->isPointerTy()) { | |||
1870 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1871, __extension__ __PRETTY_FUNCTION__)) | |||
1871 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1871, __extension__ __PRETTY_FUNCTION__)); | |||
1872 | } else { | |||
1873 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1874, __extension__ __PRETTY_FUNCTION__)) | |||
1874 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1874, __extension__ __PRETTY_FUNCTION__)); | |||
1875 | } | |||
1876 | #endif | |||
1877 | ||||
1878 | const APInt *C; | |||
1879 | if (match(V, m_APInt(C))) { | |||
1880 | // We know all of the bits for a scalar constant or a splat vector constant! | |||
1881 | Known = KnownBits::makeConstant(*C); | |||
1882 | return; | |||
1883 | } | |||
1884 | // Null and aggregate-zero are all-zeros. | |||
1885 | if (isa<ConstantPointerNull>(V) || isa<ConstantAggregateZero>(V)) { | |||
1886 | Known.setAllZero(); | |||
1887 | return; | |||
1888 | } | |||
1889 | // Handle a constant vector by taking the intersection of the known bits of | |||
1890 | // each element. | |||
1891 | if (const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(V)) { | |||
1892 | // We know that CDV must be a vector of integers. Take the intersection of | |||
1893 | // each element. | |||
1894 | Known.Zero.setAllBits(); Known.One.setAllBits(); | |||
1895 | for (unsigned i = 0, e = CDV->getNumElements(); i != e; ++i) { | |||
1896 | if (!DemandedElts[i]) | |||
1897 | continue; | |||
1898 | APInt Elt = CDV->getElementAsAPInt(i); | |||
1899 | Known.Zero &= ~Elt; | |||
1900 | Known.One &= Elt; | |||
1901 | } | |||
1902 | return; | |||
1903 | } | |||
1904 | ||||
1905 | if (const auto *CV = dyn_cast<ConstantVector>(V)) { | |||
1906 | // We know that CV must be a vector of integers. Take the intersection of | |||
1907 | // each element. | |||
1908 | Known.Zero.setAllBits(); Known.One.setAllBits(); | |||
1909 | for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) { | |||
1910 | if (!DemandedElts[i]) | |||
1911 | continue; | |||
1912 | Constant *Element = CV->getAggregateElement(i); | |||
1913 | auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element); | |||
1914 | if (!ElementCI) { | |||
1915 | Known.resetAll(); | |||
1916 | return; | |||
1917 | } | |||
1918 | const APInt &Elt = ElementCI->getValue(); | |||
1919 | Known.Zero &= ~Elt; | |||
1920 | Known.One &= Elt; | |||
1921 | } | |||
1922 | return; | |||
1923 | } | |||
1924 | ||||
1925 | // Start out not knowing anything. | |||
1926 | Known.resetAll(); | |||
1927 | ||||
1928 | // We can't imply anything about undefs. | |||
1929 | if (isa<UndefValue>(V)) | |||
1930 | return; | |||
1931 | ||||
1932 | // There's no point in looking through other users of ConstantData for | |||
1933 | // assumptions. Confirm that we've handled them all. | |||
1934 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1934, __extension__ __PRETTY_FUNCTION__)); | |||
1935 | ||||
1936 | // All recursive calls that increase depth must come after this. | |||
1937 | if (Depth == MaxAnalysisRecursionDepth) | |||
1938 | return; | |||
1939 | ||||
1940 | // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has | |||
1941 | // the bits of its aliasee. | |||
1942 | if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { | |||
1943 | if (!GA->isInterposable()) | |||
1944 | computeKnownBits(GA->getAliasee(), Known, Depth + 1, Q); | |||
1945 | return; | |||
1946 | } | |||
1947 | ||||
1948 | if (const Operator *I = dyn_cast<Operator>(V)) | |||
1949 | computeKnownBitsFromOperator(I, DemandedElts, Known, Depth, Q); | |||
1950 | ||||
1951 | // Aligned pointers have trailing zeros - refine Known.Zero set | |||
1952 | if (isa<PointerType>(V->getType())) { | |||
1953 | Align Alignment = V->getPointerAlignment(Q.DL); | |||
1954 | Known.Zero.setLowBits(Log2(Alignment)); | |||
1955 | } | |||
1956 | ||||
1957 | // computeKnownBitsFromAssume strictly refines Known. | |||
1958 | // Therefore, we run them after computeKnownBitsFromOperator. | |||
1959 | ||||
1960 | // Check whether a nearby assume intrinsic can determine some known bits. | |||
1961 | computeKnownBitsFromAssume(V, Known, Depth, Q); | |||
1962 | ||||
1963 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1963, __extension__ __PRETTY_FUNCTION__)); | |||
1964 | } | |||
1965 | ||||
1966 | /// Return true if the given value is known to have exactly one | |||
1967 | /// bit set when defined. For vectors return true if every element is known to | |||
1968 | /// be a power of two when defined. Supports values with integer or pointer | |||
1969 | /// types and vectors of integers. | |||
1970 | bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, | |||
1971 | const Query &Q) { | |||
1972 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 1972, __extension__ __PRETTY_FUNCTION__)); | |||
1973 | ||||
1974 | // Attempt to match against constants. | |||
1975 | if (OrZero && match(V, m_Power2OrZero())) | |||
1976 | return true; | |||
1977 | if (match(V, m_Power2())) | |||
1978 | return true; | |||
1979 | ||||
1980 | // 1 << X is clearly a power of two if the one is not shifted off the end. If | |||
1981 | // it is shifted off the end then the result is undefined. | |||
1982 | if (match(V, m_Shl(m_One(), m_Value()))) | |||
1983 | return true; | |||
1984 | ||||
1985 | // (signmask) >>l X is clearly a power of two if the one is not shifted off | |||
1986 | // the bottom. If it is shifted off the bottom then the result is undefined. | |||
1987 | if (match(V, m_LShr(m_SignMask(), m_Value()))) | |||
1988 | return true; | |||
1989 | ||||
1990 | // The remaining tests are all recursive, so bail out if we hit the limit. | |||
1991 | if (Depth++ == MaxAnalysisRecursionDepth) | |||
1992 | return false; | |||
1993 | ||||
1994 | Value *X = nullptr, *Y = nullptr; | |||
1995 | // A shift left or a logical shift right of a power of two is a power of two | |||
1996 | // or zero. | |||
1997 | if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) || | |||
1998 | match(V, m_LShr(m_Value(X), m_Value())))) | |||
1999 | return isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q); | |||
2000 | ||||
2001 | if (const ZExtInst *ZI = dyn_cast<ZExtInst>(V)) | |||
2002 | return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth, Q); | |||
2003 | ||||
2004 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) | |||
2005 | return isKnownToBeAPowerOfTwo(SI->getTrueValue(), OrZero, Depth, Q) && | |||
2006 | isKnownToBeAPowerOfTwo(SI->getFalseValue(), OrZero, Depth, Q); | |||
2007 | ||||
2008 | // Peek through min/max. | |||
2009 | if (match(V, m_MaxOrMin(m_Value(X), m_Value(Y)))) { | |||
2010 | return isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q) && | |||
2011 | isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q); | |||
2012 | } | |||
2013 | ||||
2014 | if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) { | |||
2015 | // A power of two and'd with anything is a power of two or zero. | |||
2016 | if (isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q) || | |||
2017 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, Depth, Q)) | |||
2018 | return true; | |||
2019 | // X & (-X) is always a power of two or zero. | |||
2020 | if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X)))) | |||
2021 | return true; | |||
2022 | return false; | |||
2023 | } | |||
2024 | ||||
2025 | // Adding a power-of-two or zero to the same power-of-two or zero yields | |||
2026 | // either the original power-of-two, a larger power-of-two or zero. | |||
2027 | if (match(V, m_Add(m_Value(X), m_Value(Y)))) { | |||
2028 | const OverflowingBinaryOperator *VOBO = cast<OverflowingBinaryOperator>(V); | |||
2029 | if (OrZero || Q.IIQ.hasNoUnsignedWrap(VOBO) || | |||
2030 | Q.IIQ.hasNoSignedWrap(VOBO)) { | |||
2031 | if (match(X, m_And(m_Specific(Y), m_Value())) || | |||
2032 | match(X, m_And(m_Value(), m_Specific(Y)))) | |||
2033 | if (isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q)) | |||
2034 | return true; | |||
2035 | if (match(Y, m_And(m_Specific(X), m_Value())) || | |||
2036 | match(Y, m_And(m_Value(), m_Specific(X)))) | |||
2037 | if (isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q)) | |||
2038 | return true; | |||
2039 | ||||
2040 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); | |||
2041 | KnownBits LHSBits(BitWidth); | |||
2042 | computeKnownBits(X, LHSBits, Depth, Q); | |||
2043 | ||||
2044 | KnownBits RHSBits(BitWidth); | |||
2045 | computeKnownBits(Y, RHSBits, Depth, Q); | |||
2046 | // If i8 V is a power of two or zero: | |||
2047 | // ZeroBits: 1 1 1 0 1 1 1 1 | |||
2048 | // ~ZeroBits: 0 0 0 1 0 0 0 0 | |||
2049 | if ((~(LHSBits.Zero & RHSBits.Zero)).isPowerOf2()) | |||
2050 | // If OrZero isn't set, we cannot give back a zero result. | |||
2051 | // Make sure either the LHS or RHS has a bit set. | |||
2052 | if (OrZero || RHSBits.One.getBoolValue() || LHSBits.One.getBoolValue()) | |||
2053 | return true; | |||
2054 | } | |||
2055 | } | |||
2056 | ||||
2057 | // An exact divide or right shift can only shift off zero bits, so the result | |||
2058 | // is a power of two only if the first operand is a power of two and not | |||
2059 | // copying a sign bit (sdiv int_min, 2). | |||
2060 | if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) || | |||
2061 | match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) { | |||
2062 | return isKnownToBeAPowerOfTwo(cast<Operator>(V)->getOperand(0), OrZero, | |||
2063 | Depth, Q); | |||
2064 | } | |||
2065 | ||||
2066 | return false; | |||
2067 | } | |||
2068 | ||||
2069 | /// Test whether a GEP's result is known to be non-null. | |||
2070 | /// | |||
2071 | /// Uses properties inherent in a GEP to try to determine whether it is known | |||
2072 | /// to be non-null. | |||
2073 | /// | |||
2074 | /// Currently this routine does not support vector GEPs. | |||
2075 | static bool isGEPKnownNonNull(const GEPOperator *GEP, unsigned Depth, | |||
2076 | const Query &Q) { | |||
2077 | const Function *F = nullptr; | |||
2078 | if (const Instruction *I = dyn_cast<Instruction>(GEP)) | |||
2079 | F = I->getFunction(); | |||
2080 | ||||
2081 | if (!GEP->isInBounds() || | |||
2082 | NullPointerIsDefined(F, GEP->getPointerAddressSpace())) | |||
2083 | return false; | |||
2084 | ||||
2085 | // FIXME: Support vector-GEPs. | |||
2086 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2086, __extension__ __PRETTY_FUNCTION__)); | |||
2087 | ||||
2088 | // If the base pointer is non-null, we cannot walk to a null address with an | |||
2089 | // inbounds GEP in address space zero. | |||
2090 | if (isKnownNonZero(GEP->getPointerOperand(), Depth, Q)) | |||
2091 | return true; | |||
2092 | ||||
2093 | // Walk the GEP operands and see if any operand introduces a non-zero offset. | |||
2094 | // If so, then the GEP cannot produce a null pointer, as doing so would | |||
2095 | // inherently violate the inbounds contract within address space zero. | |||
2096 | for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP); | |||
2097 | GTI != GTE; ++GTI) { | |||
2098 | // Struct types are easy -- they must always be indexed by a constant. | |||
2099 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
2100 | ConstantInt *OpC = cast<ConstantInt>(GTI.getOperand()); | |||
2101 | unsigned ElementIdx = OpC->getZExtValue(); | |||
2102 | const StructLayout *SL = Q.DL.getStructLayout(STy); | |||
2103 | uint64_t ElementOffset = SL->getElementOffset(ElementIdx); | |||
2104 | if (ElementOffset > 0) | |||
2105 | return true; | |||
2106 | continue; | |||
2107 | } | |||
2108 | ||||
2109 | // If we have a zero-sized type, the index doesn't matter. Keep looping. | |||
2110 | if (Q.DL.getTypeAllocSize(GTI.getIndexedType()).getKnownMinSize() == 0) | |||
2111 | continue; | |||
2112 | ||||
2113 | // Fast path the constant operand case both for efficiency and so we don't | |||
2114 | // increment Depth when just zipping down an all-constant GEP. | |||
2115 | if (ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand())) { | |||
2116 | if (!OpC->isZero()) | |||
2117 | return true; | |||
2118 | continue; | |||
2119 | } | |||
2120 | ||||
2121 | // We post-increment Depth here because while isKnownNonZero increments it | |||
2122 | // as well, when we pop back up that increment won't persist. We don't want | |||
2123 | // to recurse 10k times just because we have 10k GEP operands. We don't | |||
2124 | // bail completely out because we want to handle constant GEPs regardless | |||
2125 | // of depth. | |||
2126 | if (Depth++ >= MaxAnalysisRecursionDepth) | |||
2127 | continue; | |||
2128 | ||||
2129 | if (isKnownNonZero(GTI.getOperand(), Depth, Q)) | |||
2130 | return true; | |||
2131 | } | |||
2132 | ||||
2133 | return false; | |||
2134 | } | |||
2135 | ||||
2136 | static bool isKnownNonNullFromDominatingCondition(const Value *V, | |||
2137 | const Instruction *CtxI, | |||
2138 | const DominatorTree *DT) { | |||
2139 | if (isa<Constant>(V)) | |||
2140 | return false; | |||
2141 | ||||
2142 | if (!CtxI || !DT) | |||
2143 | return false; | |||
2144 | ||||
2145 | unsigned NumUsesExplored = 0; | |||
2146 | for (auto *U : V->users()) { | |||
2147 | // Avoid massive lists | |||
2148 | if (NumUsesExplored >= DomConditionsMaxUses) | |||
2149 | break; | |||
2150 | NumUsesExplored++; | |||
2151 | ||||
2152 | // If the value is used as an argument to a call or invoke, then argument | |||
2153 | // attributes may provide an answer about null-ness. | |||
2154 | if (const auto *CB = dyn_cast<CallBase>(U)) | |||
2155 | if (auto *CalledFunc = CB->getCalledFunction()) | |||
2156 | for (const Argument &Arg : CalledFunc->args()) | |||
2157 | if (CB->getArgOperand(Arg.getArgNo()) == V && | |||
2158 | Arg.hasNonNullAttr(/* AllowUndefOrPoison */ false) && | |||
2159 | DT->dominates(CB, CtxI)) | |||
2160 | return true; | |||
2161 | ||||
2162 | // If the value is used as a load/store, then the pointer must be non null. | |||
2163 | if (V == getLoadStorePointerOperand(U)) { | |||
2164 | const Instruction *I = cast<Instruction>(U); | |||
2165 | if (!NullPointerIsDefined(I->getFunction(), | |||
2166 | V->getType()->getPointerAddressSpace()) && | |||
2167 | DT->dominates(I, CtxI)) | |||
2168 | return true; | |||
2169 | } | |||
2170 | ||||
2171 | // Consider only compare instructions uniquely controlling a branch | |||
2172 | Value *RHS; | |||
2173 | CmpInst::Predicate Pred; | |||
2174 | if (!match(U, m_c_ICmp(Pred, m_Specific(V), m_Value(RHS)))) | |||
2175 | continue; | |||
2176 | ||||
2177 | bool NonNullIfTrue; | |||
2178 | if (cmpExcludesZero(Pred, RHS)) | |||
2179 | NonNullIfTrue = true; | |||
2180 | else if (cmpExcludesZero(CmpInst::getInversePredicate(Pred), RHS)) | |||
2181 | NonNullIfTrue = false; | |||
2182 | else | |||
2183 | continue; | |||
2184 | ||||
2185 | SmallVector<const User *, 4> WorkList; | |||
2186 | SmallPtrSet<const User *, 4> Visited; | |||
2187 | for (auto *CmpU : U->users()) { | |||
2188 | assert(WorkList.empty() && "Should be!")(static_cast <bool> (WorkList.empty() && "Should be!" ) ? void (0) : __assert_fail ("WorkList.empty() && \"Should be!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2188, __extension__ __PRETTY_FUNCTION__)); | |||
2189 | if (Visited.insert(CmpU).second) | |||
2190 | WorkList.push_back(CmpU); | |||
2191 | ||||
2192 | while (!WorkList.empty()) { | |||
2193 | auto *Curr = WorkList.pop_back_val(); | |||
2194 | ||||
2195 | // If a user is an AND, add all its users to the work list. We only | |||
2196 | // propagate "pred != null" condition through AND because it is only | |||
2197 | // correct to assume that all conditions of AND are met in true branch. | |||
2198 | // TODO: Support similar logic of OR and EQ predicate? | |||
2199 | if (NonNullIfTrue) | |||
2200 | if (match(Curr, m_LogicalAnd(m_Value(), m_Value()))) { | |||
2201 | for (auto *CurrU : Curr->users()) | |||
2202 | if (Visited.insert(CurrU).second) | |||
2203 | WorkList.push_back(CurrU); | |||
2204 | continue; | |||
2205 | } | |||
2206 | ||||
2207 | if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) { | |||
2208 | assert(BI->isConditional() && "uses a comparison!")(static_cast <bool> (BI->isConditional() && "uses a comparison!" ) ? void (0) : __assert_fail ("BI->isConditional() && \"uses a comparison!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2208, __extension__ __PRETTY_FUNCTION__)); | |||
2209 | ||||
2210 | BasicBlock *NonNullSuccessor = | |||
2211 | BI->getSuccessor(NonNullIfTrue ? 0 : 1); | |||
2212 | BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor); | |||
2213 | if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent())) | |||
2214 | return true; | |||
2215 | } else if (NonNullIfTrue && isGuard(Curr) && | |||
2216 | DT->dominates(cast<Instruction>(Curr), CtxI)) { | |||
2217 | return true; | |||
2218 | } | |||
2219 | } | |||
2220 | } | |||
2221 | } | |||
2222 | ||||
2223 | return false; | |||
2224 | } | |||
2225 | ||||
2226 | /// Does the 'Range' metadata (which must be a valid MD_range operand list) | |||
2227 | /// ensure that the value it's attached to is never Value? 'RangeType' is | |||
2228 | /// is the type of the value described by the range. | |||
2229 | static bool rangeMetadataExcludesValue(const MDNode* Ranges, const APInt& Value) { | |||
2230 | const unsigned NumRanges = Ranges->getNumOperands() / 2; | |||
2231 | assert(NumRanges >= 1)(static_cast <bool> (NumRanges >= 1) ? void (0) : __assert_fail ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2231, __extension__ __PRETTY_FUNCTION__)); | |||
2232 | for (unsigned i = 0; i < NumRanges; ++i) { | |||
2233 | ConstantInt *Lower = | |||
2234 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 0)); | |||
2235 | ConstantInt *Upper = | |||
2236 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 1)); | |||
2237 | ConstantRange Range(Lower->getValue(), Upper->getValue()); | |||
2238 | if (Range.contains(Value)) | |||
2239 | return false; | |||
2240 | } | |||
2241 | return true; | |||
2242 | } | |||
2243 | ||||
2244 | /// Try to detect a recurrence that monotonically increases/decreases from a | |||
2245 | /// non-zero starting value. These are common as induction variables. | |||
2246 | static bool isNonZeroRecurrence(const PHINode *PN) { | |||
2247 | BinaryOperator *BO = nullptr; | |||
2248 | Value *Start = nullptr, *Step = nullptr; | |||
2249 | const APInt *StartC, *StepC; | |||
2250 | if (!matchSimpleRecurrence(PN, BO, Start, Step) || | |||
2251 | !match(Start, m_APInt(StartC)) || StartC->isNullValue()) | |||
2252 | return false; | |||
2253 | ||||
2254 | switch (BO->getOpcode()) { | |||
2255 | case Instruction::Add: | |||
2256 | // Starting from non-zero and stepping away from zero can never wrap back | |||
2257 | // to zero. | |||
2258 | return BO->hasNoUnsignedWrap() || | |||
2259 | (BO->hasNoSignedWrap() && match(Step, m_APInt(StepC)) && | |||
2260 | StartC->isNegative() == StepC->isNegative()); | |||
2261 | case Instruction::Mul: | |||
2262 | return (BO->hasNoUnsignedWrap() || BO->hasNoSignedWrap()) && | |||
2263 | match(Step, m_APInt(StepC)) && !StepC->isNullValue(); | |||
2264 | case Instruction::Shl: | |||
2265 | return BO->hasNoUnsignedWrap() || BO->hasNoSignedWrap(); | |||
2266 | case Instruction::AShr: | |||
2267 | case Instruction::LShr: | |||
2268 | return BO->isExact(); | |||
2269 | default: | |||
2270 | return false; | |||
2271 | } | |||
2272 | } | |||
2273 | ||||
2274 | /// Return true if the given value is known to be non-zero when defined. For | |||
2275 | /// vectors, return true if every demanded element is known to be non-zero when | |||
2276 | /// defined. For pointers, if the context instruction and dominator tree are | |||
2277 | /// specified, perform context-sensitive analysis and return true if the | |||
2278 | /// pointer couldn't possibly be null at the specified instruction. | |||
2279 | /// Supports values with integer or pointer type and vectors of integers. | |||
2280 | bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth, | |||
2281 | const Query &Q) { | |||
2282 | // FIXME: We currently have no way to represent the DemandedElts of a scalable | |||
2283 | // vector | |||
2284 | if (isa<ScalableVectorType>(V->getType())) | |||
2285 | return false; | |||
2286 | ||||
2287 | if (auto *C = dyn_cast<Constant>(V)) { | |||
2288 | if (C->isNullValue()) | |||
2289 | return false; | |||
2290 | if (isa<ConstantInt>(C)) | |||
2291 | // Must be non-zero due to null test above. | |||
2292 | return true; | |||
2293 | ||||
2294 | if (auto *CE = dyn_cast<ConstantExpr>(C)) { | |||
2295 | // See the comment for IntToPtr/PtrToInt instructions below. | |||
2296 | if (CE->getOpcode() == Instruction::IntToPtr || | |||
2297 | CE->getOpcode() == Instruction::PtrToInt) | |||
2298 | if (Q.DL.getTypeSizeInBits(CE->getOperand(0)->getType()) | |||
2299 | .getFixedSize() <= | |||
2300 | Q.DL.getTypeSizeInBits(CE->getType()).getFixedSize()) | |||
2301 | return isKnownNonZero(CE->getOperand(0), Depth, Q); | |||
2302 | } | |||
2303 | ||||
2304 | // For constant vectors, check that all elements are undefined or known | |||
2305 | // non-zero to determine that the whole vector is known non-zero. | |||
2306 | if (auto *VecTy = dyn_cast<FixedVectorType>(C->getType())) { | |||
2307 | for (unsigned i = 0, e = VecTy->getNumElements(); i != e; ++i) { | |||
2308 | if (!DemandedElts[i]) | |||
2309 | continue; | |||
2310 | Constant *Elt = C->getAggregateElement(i); | |||
2311 | if (!Elt || Elt->isNullValue()) | |||
2312 | return false; | |||
2313 | if (!isa<UndefValue>(Elt) && !isa<ConstantInt>(Elt)) | |||
2314 | return false; | |||
2315 | } | |||
2316 | return true; | |||
2317 | } | |||
2318 | ||||
2319 | // A global variable in address space 0 is non null unless extern weak | |||
2320 | // or an absolute symbol reference. Other address spaces may have null as a | |||
2321 | // valid address for a global, so we can't assume anything. | |||
2322 | if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) { | |||
2323 | if (!GV->isAbsoluteSymbolRef() && !GV->hasExternalWeakLinkage() && | |||
2324 | GV->getType()->getAddressSpace() == 0) | |||
2325 | return true; | |||
2326 | } else | |||
2327 | return false; | |||
2328 | } | |||
2329 | ||||
2330 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
2331 | if (MDNode *Ranges = Q.IIQ.getMetadata(I, LLVMContext::MD_range)) { | |||
2332 | // If the possible ranges don't contain zero, then the value is | |||
2333 | // definitely non-zero. | |||
2334 | if (auto *Ty = dyn_cast<IntegerType>(V->getType())) { | |||
2335 | const APInt ZeroValue(Ty->getBitWidth(), 0); | |||
2336 | if (rangeMetadataExcludesValue(Ranges, ZeroValue)) | |||
2337 | return true; | |||
2338 | } | |||
2339 | } | |||
2340 | } | |||
2341 | ||||
2342 | if (isKnownNonZeroFromAssume(V, Q)) | |||
2343 | return true; | |||
2344 | ||||
2345 | // Some of the tests below are recursive, so bail out if we hit the limit. | |||
2346 | if (Depth++ >= MaxAnalysisRecursionDepth) | |||
2347 | return false; | |||
2348 | ||||
2349 | // Check for pointer simplifications. | |||
2350 | ||||
2351 | if (PointerType *PtrTy = dyn_cast<PointerType>(V->getType())) { | |||
2352 | // Alloca never returns null, malloc might. | |||
2353 | if (isa<AllocaInst>(V) && Q.DL.getAllocaAddrSpace() == 0) | |||
2354 | return true; | |||
2355 | ||||
2356 | // A byval, inalloca may not be null in a non-default addres space. A | |||
2357 | // nonnull argument is assumed never 0. | |||
2358 | if (const Argument *A = dyn_cast<Argument>(V)) { | |||
2359 | if (((A->hasPassPointeeByValueCopyAttr() && | |||
2360 | !NullPointerIsDefined(A->getParent(), PtrTy->getAddressSpace())) || | |||
2361 | A->hasNonNullAttr())) | |||
2362 | return true; | |||
2363 | } | |||
2364 | ||||
2365 | // A Load tagged with nonnull metadata is never null. | |||
2366 | if (const LoadInst *LI = dyn_cast<LoadInst>(V)) | |||
2367 | if (Q.IIQ.getMetadata(LI, LLVMContext::MD_nonnull)) | |||
2368 | return true; | |||
2369 | ||||
2370 | if (const auto *Call = dyn_cast<CallBase>(V)) { | |||
2371 | if (Call->isReturnNonNull()) | |||
2372 | return true; | |||
2373 | if (const auto *RP = getArgumentAliasingToReturnedPointer(Call, true)) | |||
2374 | return isKnownNonZero(RP, Depth, Q); | |||
2375 | } | |||
2376 | } | |||
2377 | ||||
2378 | if (isKnownNonNullFromDominatingCondition(V, Q.CxtI, Q.DT)) | |||
2379 | return true; | |||
2380 | ||||
2381 | // Check for recursive pointer simplifications. | |||
2382 | if (V->getType()->isPointerTy()) { | |||
2383 | // Look through bitcast operations, GEPs, and int2ptr instructions as they | |||
2384 | // do not alter the value, or at least not the nullness property of the | |||
2385 | // value, e.g., int2ptr is allowed to zero/sign extend the value. | |||
2386 | // | |||
2387 | // Note that we have to take special care to avoid looking through | |||
2388 | // truncating casts, e.g., int2ptr/ptr2int with appropriate sizes, as well | |||
2389 | // as casts that can alter the value, e.g., AddrSpaceCasts. | |||
2390 | if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) | |||
2391 | return isGEPKnownNonNull(GEP, Depth, Q); | |||
2392 | ||||
2393 | if (auto *BCO = dyn_cast<BitCastOperator>(V)) | |||
2394 | return isKnownNonZero(BCO->getOperand(0), Depth, Q); | |||
2395 | ||||
2396 | if (auto *I2P = dyn_cast<IntToPtrInst>(V)) | |||
2397 | if (Q.DL.getTypeSizeInBits(I2P->getSrcTy()).getFixedSize() <= | |||
2398 | Q.DL.getTypeSizeInBits(I2P->getDestTy()).getFixedSize()) | |||
2399 | return isKnownNonZero(I2P->getOperand(0), Depth, Q); | |||
2400 | } | |||
2401 | ||||
2402 | // Similar to int2ptr above, we can look through ptr2int here if the cast | |||
2403 | // is a no-op or an extend and not a truncate. | |||
2404 | if (auto *P2I = dyn_cast<PtrToIntInst>(V)) | |||
2405 | if (Q.DL.getTypeSizeInBits(P2I->getSrcTy()).getFixedSize() <= | |||
2406 | Q.DL.getTypeSizeInBits(P2I->getDestTy()).getFixedSize()) | |||
2407 | return isKnownNonZero(P2I->getOperand(0), Depth, Q); | |||
2408 | ||||
2409 | unsigned BitWidth = getBitWidth(V->getType()->getScalarType(), Q.DL); | |||
2410 | ||||
2411 | // X | Y != 0 if X != 0 or Y != 0. | |||
2412 | Value *X = nullptr, *Y = nullptr; | |||
2413 | if (match(V, m_Or(m_Value(X), m_Value(Y)))) | |||
2414 | return isKnownNonZero(X, DemandedElts, Depth, Q) || | |||
2415 | isKnownNonZero(Y, DemandedElts, Depth, Q); | |||
2416 | ||||
2417 | // ext X != 0 if X != 0. | |||
2418 | if (isa<SExtInst>(V) || isa<ZExtInst>(V)) | |||
2419 | return isKnownNonZero(cast<Instruction>(V)->getOperand(0), Depth, Q); | |||
2420 | ||||
2421 | // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined | |||
2422 | // if the lowest bit is shifted off the end. | |||
2423 | if (match(V, m_Shl(m_Value(X), m_Value(Y)))) { | |||
2424 | // shl nuw can't remove any non-zero bits. | |||
2425 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); | |||
2426 | if (Q.IIQ.hasNoUnsignedWrap(BO)) | |||
2427 | return isKnownNonZero(X, Depth, Q); | |||
2428 | ||||
2429 | KnownBits Known(BitWidth); | |||
2430 | computeKnownBits(X, DemandedElts, Known, Depth, Q); | |||
2431 | if (Known.One[0]) | |||
2432 | return true; | |||
2433 | } | |||
2434 | // shr X, Y != 0 if X is negative. Note that the value of the shift is not | |||
2435 | // defined if the sign bit is shifted off the end. | |||
2436 | else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) { | |||
2437 | // shr exact can only shift out zero bits. | |||
2438 | const PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V); | |||
2439 | if (BO->isExact()) | |||
2440 | return isKnownNonZero(X, Depth, Q); | |||
2441 | ||||
2442 | KnownBits Known = computeKnownBits(X, DemandedElts, Depth, Q); | |||
2443 | if (Known.isNegative()) | |||
2444 | return true; | |||
2445 | ||||
2446 | // If the shifter operand is a constant, and all of the bits shifted | |||
2447 | // out are known to be zero, and X is known non-zero then at least one | |||
2448 | // non-zero bit must remain. | |||
2449 | if (ConstantInt *Shift = dyn_cast<ConstantInt>(Y)) { | |||
2450 | auto ShiftVal = Shift->getLimitedValue(BitWidth - 1); | |||
2451 | // Is there a known one in the portion not shifted out? | |||
2452 | if (Known.countMaxLeadingZeros() < BitWidth - ShiftVal) | |||
2453 | return true; | |||
2454 | // Are all the bits to be shifted out known zero? | |||
2455 | if (Known.countMinTrailingZeros() >= ShiftVal) | |||
2456 | return isKnownNonZero(X, DemandedElts, Depth, Q); | |||
2457 | } | |||
2458 | } | |||
2459 | // div exact can only produce a zero if the dividend is zero. | |||
2460 | else if (match(V, m_Exact(m_IDiv(m_Value(X), m_Value())))) { | |||
2461 | return isKnownNonZero(X, DemandedElts, Depth, Q); | |||
2462 | } | |||
2463 | // X + Y. | |||
2464 | else if (match(V, m_Add(m_Value(X), m_Value(Y)))) { | |||
2465 | KnownBits XKnown = computeKnownBits(X, DemandedElts, Depth, Q); | |||
2466 | KnownBits YKnown = computeKnownBits(Y, DemandedElts, Depth, Q); | |||
2467 | ||||
2468 | // If X and Y are both non-negative (as signed values) then their sum is not | |||
2469 | // zero unless both X and Y are zero. | |||
2470 | if (XKnown.isNonNegative() && YKnown.isNonNegative()) | |||
2471 | if (isKnownNonZero(X, DemandedElts, Depth, Q) || | |||
2472 | isKnownNonZero(Y, DemandedElts, Depth, Q)) | |||
2473 | return true; | |||
2474 | ||||
2475 | // If X and Y are both negative (as signed values) then their sum is not | |||
2476 | // zero unless both X and Y equal INT_MIN. | |||
2477 | if (XKnown.isNegative() && YKnown.isNegative()) { | |||
2478 | APInt Mask = APInt::getSignedMaxValue(BitWidth); | |||
2479 | // The sign bit of X is set. If some other bit is set then X is not equal | |||
2480 | // to INT_MIN. | |||
2481 | if (XKnown.One.intersects(Mask)) | |||
2482 | return true; | |||
2483 | // The sign bit of Y is set. If some other bit is set then Y is not equal | |||
2484 | // to INT_MIN. | |||
2485 | if (YKnown.One.intersects(Mask)) | |||
2486 | return true; | |||
2487 | } | |||
2488 | ||||
2489 | // The sum of a non-negative number and a power of two is not zero. | |||
2490 | if (XKnown.isNonNegative() && | |||
2491 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ false, Depth, Q)) | |||
2492 | return true; | |||
2493 | if (YKnown.isNonNegative() && | |||
2494 | isKnownToBeAPowerOfTwo(X, /*OrZero*/ false, Depth, Q)) | |||
2495 | return true; | |||
2496 | } | |||
2497 | // X * Y. | |||
2498 | else if (match(V, m_Mul(m_Value(X), m_Value(Y)))) { | |||
2499 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); | |||
2500 | // If X and Y are non-zero then so is X * Y as long as the multiplication | |||
2501 | // does not overflow. | |||
2502 | if ((Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO)) && | |||
2503 | isKnownNonZero(X, DemandedElts, Depth, Q) && | |||
2504 | isKnownNonZero(Y, DemandedElts, Depth, Q)) | |||
2505 | return true; | |||
2506 | } | |||
2507 | // (C ? X : Y) != 0 if X != 0 and Y != 0. | |||
2508 | else if (const SelectInst *SI = dyn_cast<SelectInst>(V)) { | |||
2509 | if (isKnownNonZero(SI->getTrueValue(), DemandedElts, Depth, Q) && | |||
2510 | isKnownNonZero(SI->getFalseValue(), DemandedElts, Depth, Q)) | |||
2511 | return true; | |||
2512 | } | |||
2513 | // PHI | |||
2514 | else if (const PHINode *PN = dyn_cast<PHINode>(V)) { | |||
2515 | if (Q.IIQ.UseInstrInfo && isNonZeroRecurrence(PN)) | |||
2516 | return true; | |||
2517 | ||||
2518 | // Check if all incoming values are non-zero using recursion. | |||
2519 | Query RecQ = Q; | |||
2520 | unsigned NewDepth = std::max(Depth, MaxAnalysisRecursionDepth - 1); | |||
2521 | return llvm::all_of(PN->operands(), [&](const Use &U) { | |||
2522 | if (U.get() == PN) | |||
2523 | return true; | |||
2524 | RecQ.CxtI = PN->getIncomingBlock(U)->getTerminator(); | |||
2525 | return isKnownNonZero(U.get(), DemandedElts, NewDepth, RecQ); | |||
2526 | }); | |||
2527 | } | |||
2528 | // ExtractElement | |||
2529 | else if (const auto *EEI = dyn_cast<ExtractElementInst>(V)) { | |||
2530 | const Value *Vec = EEI->getVectorOperand(); | |||
2531 | const Value *Idx = EEI->getIndexOperand(); | |||
2532 | auto *CIdx = dyn_cast<ConstantInt>(Idx); | |||
2533 | if (auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType())) { | |||
2534 | unsigned NumElts = VecTy->getNumElements(); | |||
2535 | APInt DemandedVecElts = APInt::getAllOnesValue(NumElts); | |||
2536 | if (CIdx && CIdx->getValue().ult(NumElts)) | |||
2537 | DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue()); | |||
2538 | return isKnownNonZero(Vec, DemandedVecElts, Depth, Q); | |||
2539 | } | |||
2540 | } | |||
2541 | // Freeze | |||
2542 | else if (const FreezeInst *FI = dyn_cast<FreezeInst>(V)) { | |||
2543 | auto *Op = FI->getOperand(0); | |||
2544 | if (isKnownNonZero(Op, Depth, Q) && | |||
2545 | isGuaranteedNotToBePoison(Op, Q.AC, Q.CxtI, Q.DT, Depth)) | |||
2546 | return true; | |||
2547 | } | |||
2548 | ||||
2549 | KnownBits Known(BitWidth); | |||
2550 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
2551 | return Known.One != 0; | |||
2552 | } | |||
2553 | ||||
2554 | bool isKnownNonZero(const Value* V, unsigned Depth, const Query& Q) { | |||
2555 | // FIXME: We currently have no way to represent the DemandedElts of a scalable | |||
2556 | // vector | |||
2557 | if (isa<ScalableVectorType>(V->getType())) | |||
2558 | return false; | |||
2559 | ||||
2560 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
2561 | APInt DemandedElts = | |||
2562 | FVTy ? APInt::getAllOnesValue(FVTy->getNumElements()) : APInt(1, 1); | |||
2563 | return isKnownNonZero(V, DemandedElts, Depth, Q); | |||
2564 | } | |||
2565 | ||||
2566 | /// If the pair of operators are the same invertible function, return the | |||
2567 | /// the operands of the function corresponding to each input. Otherwise, | |||
2568 | /// return None. An invertible function is one that is 1-to-1 and maps | |||
2569 | /// every input value to exactly one output value. This is equivalent to | |||
2570 | /// saying that Op1 and Op2 are equal exactly when the specified pair of | |||
2571 | /// operands are equal, (except that Op1 and Op2 may be poison more often.) | |||
2572 | static Optional<std::pair<Value*, Value*>> | |||
2573 | getInvertibleOperands(const Operator *Op1, | |||
2574 | const Operator *Op2) { | |||
2575 | if (Op1->getOpcode() != Op2->getOpcode()) | |||
2576 | return None; | |||
2577 | ||||
2578 | auto getOperands = [&](unsigned OpNum) -> auto { | |||
2579 | return std::make_pair(Op1->getOperand(OpNum), Op2->getOperand(OpNum)); | |||
2580 | }; | |||
2581 | ||||
2582 | switch (Op1->getOpcode()) { | |||
2583 | default: | |||
2584 | break; | |||
2585 | case Instruction::Add: | |||
2586 | case Instruction::Sub: | |||
2587 | if (Op1->getOperand(0) == Op2->getOperand(0)) | |||
2588 | return getOperands(1); | |||
2589 | if (Op1->getOperand(1) == Op2->getOperand(1)) | |||
2590 | return getOperands(0); | |||
2591 | break; | |||
2592 | case Instruction::Mul: { | |||
2593 | // invertible if A * B == (A * B) mod 2^N where A, and B are integers | |||
2594 | // and N is the bitwdith. The nsw case is non-obvious, but proven by | |||
2595 | // alive2: https://alive2.llvm.org/ce/z/Z6D5qK | |||
2596 | auto *OBO1 = cast<OverflowingBinaryOperator>(Op1); | |||
2597 | auto *OBO2 = cast<OverflowingBinaryOperator>(Op2); | |||
2598 | if ((!OBO1->hasNoUnsignedWrap() || !OBO2->hasNoUnsignedWrap()) && | |||
2599 | (!OBO1->hasNoSignedWrap() || !OBO2->hasNoSignedWrap())) | |||
2600 | break; | |||
2601 | ||||
2602 | // Assume operand order has been canonicalized | |||
2603 | if (Op1->getOperand(1) == Op2->getOperand(1) && | |||
2604 | isa<ConstantInt>(Op1->getOperand(1)) && | |||
2605 | !cast<ConstantInt>(Op1->getOperand(1))->isZero()) | |||
2606 | return getOperands(0); | |||
2607 | break; | |||
2608 | } | |||
2609 | case Instruction::Shl: { | |||
2610 | // Same as multiplies, with the difference that we don't need to check | |||
2611 | // for a non-zero multiply. Shifts always multiply by non-zero. | |||
2612 | auto *OBO1 = cast<OverflowingBinaryOperator>(Op1); | |||
2613 | auto *OBO2 = cast<OverflowingBinaryOperator>(Op2); | |||
2614 | if ((!OBO1->hasNoUnsignedWrap() || !OBO2->hasNoUnsignedWrap()) && | |||
2615 | (!OBO1->hasNoSignedWrap() || !OBO2->hasNoSignedWrap())) | |||
2616 | break; | |||
2617 | ||||
2618 | if (Op1->getOperand(1) == Op2->getOperand(1)) | |||
2619 | return getOperands(0); | |||
2620 | break; | |||
2621 | } | |||
2622 | case Instruction::AShr: | |||
2623 | case Instruction::LShr: { | |||
2624 | auto *PEO1 = cast<PossiblyExactOperator>(Op1); | |||
2625 | auto *PEO2 = cast<PossiblyExactOperator>(Op2); | |||
2626 | if (!PEO1->isExact() || !PEO2->isExact()) | |||
2627 | break; | |||
2628 | ||||
2629 | if (Op1->getOperand(1) == Op2->getOperand(1)) | |||
2630 | return getOperands(0); | |||
2631 | break; | |||
2632 | } | |||
2633 | case Instruction::SExt: | |||
2634 | case Instruction::ZExt: | |||
2635 | if (Op1->getOperand(0)->getType() == Op2->getOperand(0)->getType()) | |||
2636 | return getOperands(0); | |||
2637 | break; | |||
2638 | case Instruction::PHI: { | |||
2639 | const PHINode *PN1 = cast<PHINode>(Op1); | |||
2640 | const PHINode *PN2 = cast<PHINode>(Op2); | |||
2641 | ||||
2642 | // If PN1 and PN2 are both recurrences, can we prove the entire recurrences | |||
2643 | // are a single invertible function of the start values? Note that repeated | |||
2644 | // application of an invertible function is also invertible | |||
2645 | BinaryOperator *BO1 = nullptr; | |||
2646 | Value *Start1 = nullptr, *Step1 = nullptr; | |||
2647 | BinaryOperator *BO2 = nullptr; | |||
2648 | Value *Start2 = nullptr, *Step2 = nullptr; | |||
2649 | if (PN1->getParent() != PN2->getParent() || | |||
2650 | !matchSimpleRecurrence(PN1, BO1, Start1, Step1) || | |||
2651 | !matchSimpleRecurrence(PN2, BO2, Start2, Step2)) | |||
2652 | break; | |||
2653 | ||||
2654 | auto Values = getInvertibleOperands(cast<Operator>(BO1), | |||
2655 | cast<Operator>(BO2)); | |||
2656 | if (!Values) | |||
2657 | break; | |||
2658 | ||||
2659 | // We have to be careful of mutually defined recurrences here. Ex: | |||
2660 | // * X_i = X_(i-1) OP Y_(i-1), and Y_i = X_(i-1) OP V | |||
2661 | // * X_i = Y_i = X_(i-1) OP Y_(i-1) | |||
2662 | // The invertibility of these is complicated, and not worth reasoning | |||
2663 | // about (yet?). | |||
2664 | if (Values->first != PN1 || Values->second != PN2) | |||
2665 | break; | |||
2666 | ||||
2667 | return std::make_pair(Start1, Start2); | |||
2668 | } | |||
2669 | } | |||
2670 | return None; | |||
2671 | } | |||
2672 | ||||
2673 | /// Return true if V2 == V1 + X, where X is known non-zero. | |||
2674 | static bool isAddOfNonZero(const Value *V1, const Value *V2, unsigned Depth, | |||
2675 | const Query &Q) { | |||
2676 | const BinaryOperator *BO = dyn_cast<BinaryOperator>(V1); | |||
2677 | if (!BO || BO->getOpcode() != Instruction::Add) | |||
2678 | return false; | |||
2679 | Value *Op = nullptr; | |||
2680 | if (V2 == BO->getOperand(0)) | |||
2681 | Op = BO->getOperand(1); | |||
2682 | else if (V2 == BO->getOperand(1)) | |||
2683 | Op = BO->getOperand(0); | |||
2684 | else | |||
2685 | return false; | |||
2686 | return isKnownNonZero(Op, Depth + 1, Q); | |||
2687 | } | |||
2688 | ||||
2689 | /// Return true if V2 == V1 * C, where V1 is known non-zero, C is not 0/1 and | |||
2690 | /// the multiplication is nuw or nsw. | |||
2691 | static bool isNonEqualMul(const Value *V1, const Value *V2, unsigned Depth, | |||
2692 | const Query &Q) { | |||
2693 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) { | |||
2694 | const APInt *C; | |||
2695 | return match(OBO, m_Mul(m_Specific(V1), m_APInt(C))) && | |||
2696 | (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) && | |||
2697 | !C->isNullValue() && !C->isOneValue() && | |||
2698 | isKnownNonZero(V1, Depth + 1, Q); | |||
2699 | } | |||
2700 | return false; | |||
2701 | } | |||
2702 | ||||
2703 | /// Return true if V2 == V1 << C, where V1 is known non-zero, C is not 0 and | |||
2704 | /// the shift is nuw or nsw. | |||
2705 | static bool isNonEqualShl(const Value *V1, const Value *V2, unsigned Depth, | |||
2706 | const Query &Q) { | |||
2707 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) { | |||
2708 | const APInt *C; | |||
2709 | return match(OBO, m_Shl(m_Specific(V1), m_APInt(C))) && | |||
2710 | (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) && | |||
2711 | !C->isNullValue() && isKnownNonZero(V1, Depth + 1, Q); | |||
2712 | } | |||
2713 | return false; | |||
2714 | } | |||
2715 | ||||
2716 | static bool isNonEqualPHIs(const PHINode *PN1, const PHINode *PN2, | |||
2717 | unsigned Depth, const Query &Q) { | |||
2718 | // Check two PHIs are in same block. | |||
2719 | if (PN1->getParent() != PN2->getParent()) | |||
2720 | return false; | |||
2721 | ||||
2722 | SmallPtrSet<const BasicBlock *, 8> VisitedBBs; | |||
2723 | bool UsedFullRecursion = false; | |||
2724 | for (const BasicBlock *IncomBB : PN1->blocks()) { | |||
2725 | if (!VisitedBBs.insert(IncomBB).second) | |||
2726 | continue; // Don't reprocess blocks that we have dealt with already. | |||
2727 | const Value *IV1 = PN1->getIncomingValueForBlock(IncomBB); | |||
2728 | const Value *IV2 = PN2->getIncomingValueForBlock(IncomBB); | |||
2729 | const APInt *C1, *C2; | |||
2730 | if (match(IV1, m_APInt(C1)) && match(IV2, m_APInt(C2)) && *C1 != *C2) | |||
2731 | continue; | |||
2732 | ||||
2733 | // Only one pair of phi operands is allowed for full recursion. | |||
2734 | if (UsedFullRecursion) | |||
2735 | return false; | |||
2736 | ||||
2737 | Query RecQ = Q; | |||
2738 | RecQ.CxtI = IncomBB->getTerminator(); | |||
2739 | if (!isKnownNonEqual(IV1, IV2, Depth + 1, RecQ)) | |||
2740 | return false; | |||
2741 | UsedFullRecursion = true; | |||
2742 | } | |||
2743 | return true; | |||
2744 | } | |||
2745 | ||||
2746 | /// Return true if it is known that V1 != V2. | |||
2747 | static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth, | |||
2748 | const Query &Q) { | |||
2749 | if (V1 == V2) | |||
2750 | return false; | |||
2751 | if (V1->getType() != V2->getType()) | |||
2752 | // We can't look through casts yet. | |||
2753 | return false; | |||
2754 | ||||
2755 | if (Depth >= MaxAnalysisRecursionDepth) | |||
2756 | return false; | |||
2757 | ||||
2758 | // See if we can recurse through (exactly one of) our operands. This | |||
2759 | // requires our operation be 1-to-1 and map every input value to exactly | |||
2760 | // one output value. Such an operation is invertible. | |||
2761 | auto *O1 = dyn_cast<Operator>(V1); | |||
2762 | auto *O2 = dyn_cast<Operator>(V2); | |||
2763 | if (O1 && O2 && O1->getOpcode() == O2->getOpcode()) { | |||
2764 | if (auto Values = getInvertibleOperands(O1, O2)) | |||
2765 | return isKnownNonEqual(Values->first, Values->second, Depth + 1, Q); | |||
2766 | ||||
2767 | if (const PHINode *PN1 = dyn_cast<PHINode>(V1)) { | |||
2768 | const PHINode *PN2 = cast<PHINode>(V2); | |||
2769 | // FIXME: This is missing a generalization to handle the case where one is | |||
2770 | // a PHI and another one isn't. | |||
2771 | if (isNonEqualPHIs(PN1, PN2, Depth, Q)) | |||
2772 | return true; | |||
2773 | }; | |||
2774 | } | |||
2775 | ||||
2776 | if (isAddOfNonZero(V1, V2, Depth, Q) || isAddOfNonZero(V2, V1, Depth, Q)) | |||
2777 | return true; | |||
2778 | ||||
2779 | if (isNonEqualMul(V1, V2, Depth, Q) || isNonEqualMul(V2, V1, Depth, Q)) | |||
2780 | return true; | |||
2781 | ||||
2782 | if (isNonEqualShl(V1, V2, Depth, Q) || isNonEqualShl(V2, V1, Depth, Q)) | |||
2783 | return true; | |||
2784 | ||||
2785 | if (V1->getType()->isIntOrIntVectorTy()) { | |||
2786 | // Are any known bits in V1 contradictory to known bits in V2? If V1 | |||
2787 | // has a known zero where V2 has a known one, they must not be equal. | |||
2788 | KnownBits Known1 = computeKnownBits(V1, Depth, Q); | |||
2789 | KnownBits Known2 = computeKnownBits(V2, Depth, Q); | |||
2790 | ||||
2791 | if (Known1.Zero.intersects(Known2.One) || | |||
2792 | Known2.Zero.intersects(Known1.One)) | |||
2793 | return true; | |||
2794 | } | |||
2795 | return false; | |||
2796 | } | |||
2797 | ||||
2798 | /// Return true if 'V & Mask' is known to be zero. We use this predicate to | |||
2799 | /// simplify operations downstream. Mask is known to be zero for bits that V | |||
2800 | /// cannot have. | |||
2801 | /// | |||
2802 | /// This function is defined on values with integer type, values with pointer | |||
2803 | /// type, and vectors of integers. In the case | |||
2804 | /// where V is a vector, the mask, known zero, and known one values are the | |||
2805 | /// same width as the vector element, and the bit is set only if it is true | |||
2806 | /// for all of the elements in the vector. | |||
2807 | bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, | |||
2808 | const Query &Q) { | |||
2809 | KnownBits Known(Mask.getBitWidth()); | |||
2810 | computeKnownBits(V, Known, Depth, Q); | |||
2811 | return Mask.isSubsetOf(Known.Zero); | |||
2812 | } | |||
2813 | ||||
2814 | // Match a signed min+max clamp pattern like smax(smin(In, CHigh), CLow). | |||
2815 | // Returns the input and lower/upper bounds. | |||
2816 | static bool isSignedMinMaxClamp(const Value *Select, const Value *&In, | |||
2817 | const APInt *&CLow, const APInt *&CHigh) { | |||
2818 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2820, __extension__ __PRETTY_FUNCTION__)) | |||
2819 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2820, __extension__ __PRETTY_FUNCTION__)) | |||
2820 | "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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2820, __extension__ __PRETTY_FUNCTION__)); | |||
2821 | ||||
2822 | const Value *LHS = nullptr, *RHS = nullptr; | |||
2823 | SelectPatternFlavor SPF = matchSelectPattern(Select, LHS, RHS).Flavor; | |||
2824 | if (SPF != SPF_SMAX && SPF != SPF_SMIN) | |||
2825 | return false; | |||
2826 | ||||
2827 | if (!match(RHS, m_APInt(CLow))) | |||
2828 | return false; | |||
2829 | ||||
2830 | const Value *LHS2 = nullptr, *RHS2 = nullptr; | |||
2831 | SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor; | |||
2832 | if (getInverseMinMaxFlavor(SPF) != SPF2) | |||
2833 | return false; | |||
2834 | ||||
2835 | if (!match(RHS2, m_APInt(CHigh))) | |||
2836 | return false; | |||
2837 | ||||
2838 | if (SPF == SPF_SMIN) | |||
2839 | std::swap(CLow, CHigh); | |||
2840 | ||||
2841 | In = LHS2; | |||
2842 | return CLow->sle(*CHigh); | |||
2843 | } | |||
2844 | ||||
2845 | /// For vector constants, loop over the elements and find the constant with the | |||
2846 | /// minimum number of sign bits. Return 0 if the value is not a vector constant | |||
2847 | /// or if any element was not analyzed; otherwise, return the count for the | |||
2848 | /// element with the minimum number of sign bits. | |||
2849 | static unsigned computeNumSignBitsVectorConstant(const Value *V, | |||
2850 | const APInt &DemandedElts, | |||
2851 | unsigned TyBits) { | |||
2852 | const auto *CV = dyn_cast<Constant>(V); | |||
2853 | if (!CV || !isa<FixedVectorType>(CV->getType())) | |||
2854 | return 0; | |||
2855 | ||||
2856 | unsigned MinSignBits = TyBits; | |||
2857 | unsigned NumElts = cast<FixedVectorType>(CV->getType())->getNumElements(); | |||
2858 | for (unsigned i = 0; i != NumElts; ++i) { | |||
2859 | if (!DemandedElts[i]) | |||
2860 | continue; | |||
2861 | // If we find a non-ConstantInt, bail out. | |||
2862 | auto *Elt = dyn_cast_or_null<ConstantInt>(CV->getAggregateElement(i)); | |||
2863 | if (!Elt) | |||
2864 | return 0; | |||
2865 | ||||
2866 | MinSignBits = std::min(MinSignBits, Elt->getValue().getNumSignBits()); | |||
2867 | } | |||
2868 | ||||
2869 | return MinSignBits; | |||
2870 | } | |||
2871 | ||||
2872 | static unsigned ComputeNumSignBitsImpl(const Value *V, | |||
2873 | const APInt &DemandedElts, | |||
2874 | unsigned Depth, const Query &Q); | |||
2875 | ||||
2876 | static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts, | |||
2877 | unsigned Depth, const Query &Q) { | |||
2878 | unsigned Result = ComputeNumSignBitsImpl(V, DemandedElts, Depth, Q); | |||
2879 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2879, __extension__ __PRETTY_FUNCTION__)); | |||
2880 | return Result; | |||
2881 | } | |||
2882 | ||||
2883 | /// Return the number of times the sign bit of the register is replicated into | |||
2884 | /// the other bits. We know that at least 1 bit is always equal to the sign bit | |||
2885 | /// (itself), but other cases can give us information. For example, immediately | |||
2886 | /// after an "ashr X, 2", we know that the top 3 bits are all equal to each | |||
2887 | /// other, so we return 3. For vectors, return the number of sign bits for the | |||
2888 | /// vector element with the minimum number of known sign bits of the demanded | |||
2889 | /// elements in the vector specified by DemandedElts. | |||
2890 | static unsigned ComputeNumSignBitsImpl(const Value *V, | |||
2891 | const APInt &DemandedElts, | |||
2892 | unsigned Depth, const Query &Q) { | |||
2893 | Type *Ty = V->getType(); | |||
2894 | ||||
2895 | // FIXME: We currently have no way to represent the DemandedElts of a scalable | |||
2896 | // vector | |||
2897 | if (isa<ScalableVectorType>(Ty)) | |||
2898 | return 1; | |||
2899 | ||||
2900 | #ifndef NDEBUG | |||
2901 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2901, __extension__ __PRETTY_FUNCTION__)); | |||
2902 | ||||
2903 | if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) { | |||
2904 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2906, __extension__ __PRETTY_FUNCTION__)) | |||
2905 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2906, __extension__ __PRETTY_FUNCTION__)) | |||
2906 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2906, __extension__ __PRETTY_FUNCTION__)); | |||
2907 | } else { | |||
2908 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2909, __extension__ __PRETTY_FUNCTION__)) | |||
2909 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 2909, __extension__ __PRETTY_FUNCTION__)); | |||
2910 | } | |||
2911 | #endif | |||
2912 | ||||
2913 | // We return the minimum number of sign bits that are guaranteed to be present | |||
2914 | // in V, so for undef we have to conservatively return 1. We don't have the | |||
2915 | // same behavior for poison though -- that's a FIXME today. | |||
2916 | ||||
2917 | Type *ScalarTy = Ty->getScalarType(); | |||
2918 | unsigned TyBits = ScalarTy->isPointerTy() ? | |||
2919 | Q.DL.getPointerTypeSizeInBits(ScalarTy) : | |||
2920 | Q.DL.getTypeSizeInBits(ScalarTy); | |||
2921 | ||||
2922 | unsigned Tmp, Tmp2; | |||
2923 | unsigned FirstAnswer = 1; | |||
2924 | ||||
2925 | // Note that ConstantInt is handled by the general computeKnownBits case | |||
2926 | // below. | |||
2927 | ||||
2928 | if (Depth == MaxAnalysisRecursionDepth) | |||
2929 | return 1; | |||
2930 | ||||
2931 | if (auto *U = dyn_cast<Operator>(V)) { | |||
2932 | switch (Operator::getOpcode(V)) { | |||
2933 | default: break; | |||
2934 | case Instruction::SExt: | |||
2935 | Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); | |||
2936 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q) + Tmp; | |||
2937 | ||||
2938 | case Instruction::SDiv: { | |||
2939 | const APInt *Denominator; | |||
2940 | // sdiv X, C -> adds log(C) sign bits. | |||
2941 | if (match(U->getOperand(1), m_APInt(Denominator))) { | |||
2942 | ||||
2943 | // Ignore non-positive denominator. | |||
2944 | if (!Denominator->isStrictlyPositive()) | |||
2945 | break; | |||
2946 | ||||
2947 | // Calculate the incoming numerator bits. | |||
2948 | unsigned NumBits = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2949 | ||||
2950 | // Add floor(log(C)) bits to the numerator bits. | |||
2951 | return std::min(TyBits, NumBits + Denominator->logBase2()); | |||
2952 | } | |||
2953 | break; | |||
2954 | } | |||
2955 | ||||
2956 | case Instruction::SRem: { | |||
2957 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2958 | ||||
2959 | const APInt *Denominator; | |||
2960 | // srem X, C -> we know that the result is within [-C+1,C) when C is a | |||
2961 | // positive constant. This let us put a lower bound on the number of sign | |||
2962 | // bits. | |||
2963 | if (match(U->getOperand(1), m_APInt(Denominator))) { | |||
2964 | ||||
2965 | // Ignore non-positive denominator. | |||
2966 | if (Denominator->isStrictlyPositive()) { | |||
2967 | // Calculate the leading sign bit constraints by examining the | |||
2968 | // denominator. Given that the denominator is positive, there are two | |||
2969 | // cases: | |||
2970 | // | |||
2971 | // 1. The numerator is positive. The result range is [0,C) and | |||
2972 | // [0,C) u< (1 << ceilLogBase2(C)). | |||
2973 | // | |||
2974 | // 2. The numerator is negative. Then the result range is (-C,0] and | |||
2975 | // integers in (-C,0] are either 0 or >u (-1 << ceilLogBase2(C)). | |||
2976 | // | |||
2977 | // Thus a lower bound on the number of sign bits is `TyBits - | |||
2978 | // ceilLogBase2(C)`. | |||
2979 | ||||
2980 | unsigned ResBits = TyBits - Denominator->ceilLogBase2(); | |||
2981 | Tmp = std::max(Tmp, ResBits); | |||
2982 | } | |||
2983 | } | |||
2984 | return Tmp; | |||
2985 | } | |||
2986 | ||||
2987 | case Instruction::AShr: { | |||
2988 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2989 | // ashr X, C -> adds C sign bits. Vectors too. | |||
2990 | const APInt *ShAmt; | |||
2991 | if (match(U->getOperand(1), m_APInt(ShAmt))) { | |||
2992 | if (ShAmt->uge(TyBits)) | |||
2993 | break; // Bad shift. | |||
2994 | unsigned ShAmtLimited = ShAmt->getZExtValue(); | |||
2995 | Tmp += ShAmtLimited; | |||
2996 | if (Tmp > TyBits) Tmp = TyBits; | |||
2997 | } | |||
2998 | return Tmp; | |||
2999 | } | |||
3000 | case Instruction::Shl: { | |||
3001 | const APInt *ShAmt; | |||
3002 | if (match(U->getOperand(1), m_APInt(ShAmt))) { | |||
3003 | // shl destroys sign bits. | |||
3004 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3005 | if (ShAmt->uge(TyBits) || // Bad shift. | |||
3006 | ShAmt->uge(Tmp)) break; // Shifted all sign bits out. | |||
3007 | Tmp2 = ShAmt->getZExtValue(); | |||
3008 | return Tmp - Tmp2; | |||
3009 | } | |||
3010 | break; | |||
3011 | } | |||
3012 | case Instruction::And: | |||
3013 | case Instruction::Or: | |||
3014 | case Instruction::Xor: // NOT is handled here. | |||
3015 | // Logical binary ops preserve the number of sign bits at the worst. | |||
3016 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3017 | if (Tmp != 1) { | |||
3018 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3019 | FirstAnswer = std::min(Tmp, Tmp2); | |||
3020 | // We computed what we know about the sign bits as our first | |||
3021 | // answer. Now proceed to the generic code that uses | |||
3022 | // computeKnownBits, and pick whichever answer is better. | |||
3023 | } | |||
3024 | break; | |||
3025 | ||||
3026 | case Instruction::Select: { | |||
3027 | // If we have a clamp pattern, we know that the number of sign bits will | |||
3028 | // be the minimum of the clamp min/max range. | |||
3029 | const Value *X; | |||
3030 | const APInt *CLow, *CHigh; | |||
3031 | if (isSignedMinMaxClamp(U, X, CLow, CHigh)) | |||
3032 | return std::min(CLow->getNumSignBits(), CHigh->getNumSignBits()); | |||
3033 | ||||
3034 | Tmp = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3035 | if (Tmp == 1) break; | |||
3036 | Tmp2 = ComputeNumSignBits(U->getOperand(2), Depth + 1, Q); | |||
3037 | return std::min(Tmp, Tmp2); | |||
3038 | } | |||
3039 | ||||
3040 | case Instruction::Add: | |||
3041 | // Add can have at most one carry bit. Thus we know that the output | |||
3042 | // is, at worst, one more bit than the inputs. | |||
3043 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3044 | if (Tmp == 1) break; | |||
3045 | ||||
3046 | // Special case decrementing a value (ADD X, -1): | |||
3047 | if (const auto *CRHS = dyn_cast<Constant>(U->getOperand(1))) | |||
3048 | if (CRHS->isAllOnesValue()) { | |||
3049 | KnownBits Known(TyBits); | |||
3050 | computeKnownBits(U->getOperand(0), Known, Depth + 1, Q); | |||
3051 | ||||
3052 | // If the input is known to be 0 or 1, the output is 0/-1, which is | |||
3053 | // all sign bits set. | |||
3054 | if ((Known.Zero | 1).isAllOnesValue()) | |||
3055 | return TyBits; | |||
3056 | ||||
3057 | // If we are subtracting one from a positive number, there is no carry | |||
3058 | // out of the result. | |||
3059 | if (Known.isNonNegative()) | |||
3060 | return Tmp; | |||
3061 | } | |||
3062 | ||||
3063 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3064 | if (Tmp2 == 1) break; | |||
3065 | return std::min(Tmp, Tmp2) - 1; | |||
3066 | ||||
3067 | case Instruction::Sub: | |||
3068 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3069 | if (Tmp2 == 1) break; | |||
3070 | ||||
3071 | // Handle NEG. | |||
3072 | if (const auto *CLHS = dyn_cast<Constant>(U->getOperand(0))) | |||
3073 | if (CLHS->isNullValue()) { | |||
3074 | KnownBits Known(TyBits); | |||
3075 | computeKnownBits(U->getOperand(1), Known, Depth + 1, Q); | |||
3076 | // If the input is known to be 0 or 1, the output is 0/-1, which is | |||
3077 | // all sign bits set. | |||
3078 | if ((Known.Zero | 1).isAllOnesValue()) | |||
3079 | return TyBits; | |||
3080 | ||||
3081 | // If the input is known to be positive (the sign bit is known clear), | |||
3082 | // the output of the NEG has the same number of sign bits as the | |||
3083 | // input. | |||
3084 | if (Known.isNonNegative()) | |||
3085 | return Tmp2; | |||
3086 | ||||
3087 | // Otherwise, we treat this like a SUB. | |||
3088 | } | |||
3089 | ||||
3090 | // Sub can have at most one carry bit. Thus we know that the output | |||
3091 | // is, at worst, one more bit than the inputs. | |||
3092 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3093 | if (Tmp == 1) break; | |||
3094 | return std::min(Tmp, Tmp2) - 1; | |||
3095 | ||||
3096 | case Instruction::Mul: { | |||
3097 | // The output of the Mul can be at most twice the valid bits in the | |||
3098 | // inputs. | |||
3099 | unsigned SignBitsOp0 = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3100 | if (SignBitsOp0 == 1) break; | |||
3101 | unsigned SignBitsOp1 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
3102 | if (SignBitsOp1 == 1) break; | |||
3103 | unsigned OutValidBits = | |||
3104 | (TyBits - SignBitsOp0 + 1) + (TyBits - SignBitsOp1 + 1); | |||
3105 | return OutValidBits > TyBits ? 1 : TyBits - OutValidBits + 1; | |||
3106 | } | |||
3107 | ||||
3108 | case Instruction::PHI: { | |||
3109 | const PHINode *PN = cast<PHINode>(U); | |||
3110 | unsigned NumIncomingValues = PN->getNumIncomingValues(); | |||
3111 | // Don't analyze large in-degree PHIs. | |||
3112 | if (NumIncomingValues > 4) break; | |||
3113 | // Unreachable blocks may have zero-operand PHI nodes. | |||
3114 | if (NumIncomingValues == 0) break; | |||
3115 | ||||
3116 | // Take the minimum of all incoming values. This can't infinitely loop | |||
3117 | // because of our depth threshold. | |||
3118 | Query RecQ = Q; | |||
3119 | Tmp = TyBits; | |||
3120 | for (unsigned i = 0, e = NumIncomingValues; i != e; ++i) { | |||
3121 | if (Tmp == 1) return Tmp; | |||
3122 | RecQ.CxtI = PN->getIncomingBlock(i)->getTerminator(); | |||
3123 | Tmp = std::min( | |||
3124 | Tmp, ComputeNumSignBits(PN->getIncomingValue(i), Depth + 1, RecQ)); | |||
3125 | } | |||
3126 | return Tmp; | |||
3127 | } | |||
3128 | ||||
3129 | case Instruction::Trunc: | |||
3130 | // FIXME: it's tricky to do anything useful for this, but it is an | |||
3131 | // important case for targets like X86. | |||
3132 | break; | |||
3133 | ||||
3134 | case Instruction::ExtractElement: | |||
3135 | // Look through extract element. At the moment we keep this simple and | |||
3136 | // skip tracking the specific element. But at least we might find | |||
3137 | // information valid for all elements of the vector (for example if vector | |||
3138 | // is sign extended, shifted, etc). | |||
3139 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3140 | ||||
3141 | case Instruction::ShuffleVector: { | |||
3142 | // Collect the minimum number of sign bits that are shared by every vector | |||
3143 | // element referenced by the shuffle. | |||
3144 | auto *Shuf = dyn_cast<ShuffleVectorInst>(U); | |||
3145 | if (!Shuf) { | |||
3146 | // FIXME: Add support for shufflevector constant expressions. | |||
3147 | return 1; | |||
3148 | } | |||
3149 | APInt DemandedLHS, DemandedRHS; | |||
3150 | // For undef elements, we don't know anything about the common state of | |||
3151 | // the shuffle result. | |||
3152 | if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) | |||
3153 | return 1; | |||
3154 | Tmp = std::numeric_limits<unsigned>::max(); | |||
3155 | if (!!DemandedLHS) { | |||
3156 | const Value *LHS = Shuf->getOperand(0); | |||
3157 | Tmp = ComputeNumSignBits(LHS, DemandedLHS, Depth + 1, Q); | |||
3158 | } | |||
3159 | // If we don't know anything, early out and try computeKnownBits | |||
3160 | // fall-back. | |||
3161 | if (Tmp == 1) | |||
3162 | break; | |||
3163 | if (!!DemandedRHS) { | |||
3164 | const Value *RHS = Shuf->getOperand(1); | |||
3165 | Tmp2 = ComputeNumSignBits(RHS, DemandedRHS, Depth + 1, Q); | |||
3166 | Tmp = std::min(Tmp, Tmp2); | |||
3167 | } | |||
3168 | // If we don't know anything, early out and try computeKnownBits | |||
3169 | // fall-back. | |||
3170 | if (Tmp == 1) | |||
3171 | break; | |||
3172 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3172, __extension__ __PRETTY_FUNCTION__)); | |||
3173 | return Tmp; | |||
3174 | } | |||
3175 | case Instruction::Call: { | |||
3176 | if (const auto *II = dyn_cast<IntrinsicInst>(U)) { | |||
3177 | switch (II->getIntrinsicID()) { | |||
3178 | default: break; | |||
3179 | case Intrinsic::abs: | |||
3180 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
3181 | if (Tmp == 1) break; | |||
3182 | ||||
3183 | // Absolute value reduces number of sign bits by at most 1. | |||
3184 | return Tmp - 1; | |||
3185 | } | |||
3186 | } | |||
3187 | } | |||
3188 | } | |||
3189 | } | |||
3190 | ||||
3191 | // Finally, if we can prove that the top bits of the result are 0's or 1's, | |||
3192 | // use this information. | |||
3193 | ||||
3194 | // If we can examine all elements of a vector constant successfully, we're | |||
3195 | // done (we can't do any better than that). If not, keep trying. | |||
3196 | if (unsigned VecSignBits = | |||
3197 | computeNumSignBitsVectorConstant(V, DemandedElts, TyBits)) | |||
3198 | return VecSignBits; | |||
3199 | ||||
3200 | KnownBits Known(TyBits); | |||
3201 | computeKnownBits(V, DemandedElts, Known, Depth, Q); | |||
3202 | ||||
3203 | // If we know that the sign bit is either zero or one, determine the number of | |||
3204 | // identical bits in the top of the input value. | |||
3205 | return std::max(FirstAnswer, Known.countMinSignBits()); | |||
3206 | } | |||
3207 | ||||
3208 | /// This function computes the integer multiple of Base that equals V. | |||
3209 | /// If successful, it returns true and returns the multiple in | |||
3210 | /// Multiple. If unsuccessful, it returns false. It looks | |||
3211 | /// through SExt instructions only if LookThroughSExt is true. | |||
3212 | bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, | |||
3213 | bool LookThroughSExt, unsigned Depth) { | |||
3214 | assert(V && "No Value?")(static_cast <bool> (V && "No Value?") ? void ( 0) : __assert_fail ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3214, __extension__ __PRETTY_FUNCTION__)); | |||
3215 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth") ? void (0) : __assert_fail ( "Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3215, __extension__ __PRETTY_FUNCTION__)); | |||
3216 | assert(V->getType()->isIntegerTy() && "Not integer or pointer type!")(static_cast <bool> (V->getType()->isIntegerTy() && "Not integer or pointer type!") ? void (0) : __assert_fail ( "V->getType()->isIntegerTy() && \"Not integer or pointer type!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3216, __extension__ __PRETTY_FUNCTION__)); | |||
3217 | ||||
3218 | Type *T = V->getType(); | |||
3219 | ||||
3220 | ConstantInt *CI = dyn_cast<ConstantInt>(V); | |||
3221 | ||||
3222 | if (Base == 0) | |||
3223 | return false; | |||
3224 | ||||
3225 | if (Base == 1) { | |||
3226 | Multiple = V; | |||
3227 | return true; | |||
3228 | } | |||
3229 | ||||
3230 | ConstantExpr *CO = dyn_cast<ConstantExpr>(V); | |||
3231 | Constant *BaseVal = ConstantInt::get(T, Base); | |||
3232 | if (CO && CO == BaseVal) { | |||
3233 | // Multiple is 1. | |||
3234 | Multiple = ConstantInt::get(T, 1); | |||
3235 | return true; | |||
3236 | } | |||
3237 | ||||
3238 | if (CI && CI->getZExtValue() % Base == 0) { | |||
3239 | Multiple = ConstantInt::get(T, CI->getZExtValue() / Base); | |||
3240 | return true; | |||
3241 | } | |||
3242 | ||||
3243 | if (Depth == MaxAnalysisRecursionDepth) return false; | |||
3244 | ||||
3245 | Operator *I = dyn_cast<Operator>(V); | |||
3246 | if (!I) return false; | |||
3247 | ||||
3248 | switch (I->getOpcode()) { | |||
3249 | default: break; | |||
3250 | case Instruction::SExt: | |||
3251 | if (!LookThroughSExt) return false; | |||
3252 | // otherwise fall through to ZExt | |||
3253 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
3254 | case Instruction::ZExt: | |||
3255 | return ComputeMultiple(I->getOperand(0), Base, Multiple, | |||
3256 | LookThroughSExt, Depth+1); | |||
3257 | case Instruction::Shl: | |||
3258 | case Instruction::Mul: { | |||
3259 | Value *Op0 = I->getOperand(0); | |||
3260 | Value *Op1 = I->getOperand(1); | |||
3261 | ||||
3262 | if (I->getOpcode() == Instruction::Shl) { | |||
3263 | ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1); | |||
3264 | if (!Op1CI) return false; | |||
3265 | // Turn Op0 << Op1 into Op0 * 2^Op1 | |||
3266 | APInt Op1Int = Op1CI->getValue(); | |||
3267 | uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1); | |||
3268 | APInt API(Op1Int.getBitWidth(), 0); | |||
3269 | API.setBit(BitToSet); | |||
3270 | Op1 = ConstantInt::get(V->getContext(), API); | |||
3271 | } | |||
3272 | ||||
3273 | Value *Mul0 = nullptr; | |||
3274 | if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) { | |||
3275 | if (Constant *Op1C = dyn_cast<Constant>(Op1)) | |||
3276 | if (Constant *MulC = dyn_cast<Constant>(Mul0)) { | |||
3277 | if (Op1C->getType()->getPrimitiveSizeInBits().getFixedSize() < | |||
3278 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) | |||
3279 | Op1C = ConstantExpr::getZExt(Op1C, MulC->getType()); | |||
3280 | if (Op1C->getType()->getPrimitiveSizeInBits().getFixedSize() > | |||
3281 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) | |||
3282 | MulC = ConstantExpr::getZExt(MulC, Op1C->getType()); | |||
3283 | ||||
3284 | // V == Base * (Mul0 * Op1), so return (Mul0 * Op1) | |||
3285 | Multiple = ConstantExpr::getMul(MulC, Op1C); | |||
3286 | return true; | |||
3287 | } | |||
3288 | ||||
3289 | if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0)) | |||
3290 | if (Mul0CI->getValue() == 1) { | |||
3291 | // V == Base * Op1, so return Op1 | |||
3292 | Multiple = Op1; | |||
3293 | return true; | |||
3294 | } | |||
3295 | } | |||
3296 | ||||
3297 | Value *Mul1 = nullptr; | |||
3298 | if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) { | |||
3299 | if (Constant *Op0C = dyn_cast<Constant>(Op0)) | |||
3300 | if (Constant *MulC = dyn_cast<Constant>(Mul1)) { | |||
3301 | if (Op0C->getType()->getPrimitiveSizeInBits().getFixedSize() < | |||
3302 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) | |||
3303 | Op0C = ConstantExpr::getZExt(Op0C, MulC->getType()); | |||
3304 | if (Op0C->getType()->getPrimitiveSizeInBits().getFixedSize() > | |||
3305 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) | |||
3306 | MulC = ConstantExpr::getZExt(MulC, Op0C->getType()); | |||
3307 | ||||
3308 | // V == Base * (Mul1 * Op0), so return (Mul1 * Op0) | |||
3309 | Multiple = ConstantExpr::getMul(MulC, Op0C); | |||
3310 | return true; | |||
3311 | } | |||
3312 | ||||
3313 | if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1)) | |||
3314 | if (Mul1CI->getValue() == 1) { | |||
3315 | // V == Base * Op0, so return Op0 | |||
3316 | Multiple = Op0; | |||
3317 | return true; | |||
3318 | } | |||
3319 | } | |||
3320 | } | |||
3321 | } | |||
3322 | ||||
3323 | // We could not determine if V is a multiple of Base. | |||
3324 | return false; | |||
3325 | } | |||
3326 | ||||
3327 | Intrinsic::ID llvm::getIntrinsicForCallSite(const CallBase &CB, | |||
3328 | const TargetLibraryInfo *TLI) { | |||
3329 | const Function *F = CB.getCalledFunction(); | |||
3330 | if (!F) | |||
3331 | return Intrinsic::not_intrinsic; | |||
3332 | ||||
3333 | if (F->isIntrinsic()) | |||
3334 | return F->getIntrinsicID(); | |||
3335 | ||||
3336 | // We are going to infer semantics of a library function based on mapping it | |||
3337 | // to an LLVM intrinsic. Check that the library function is available from | |||
3338 | // this callbase and in this environment. | |||
3339 | LibFunc Func; | |||
3340 | if (F->hasLocalLinkage() || !TLI || !TLI->getLibFunc(CB, Func) || | |||
3341 | !CB.onlyReadsMemory()) | |||
3342 | return Intrinsic::not_intrinsic; | |||
3343 | ||||
3344 | switch (Func) { | |||
3345 | default: | |||
3346 | break; | |||
3347 | case LibFunc_sin: | |||
3348 | case LibFunc_sinf: | |||
3349 | case LibFunc_sinl: | |||
3350 | return Intrinsic::sin; | |||
3351 | case LibFunc_cos: | |||
3352 | case LibFunc_cosf: | |||
3353 | case LibFunc_cosl: | |||
3354 | return Intrinsic::cos; | |||
3355 | case LibFunc_exp: | |||
3356 | case LibFunc_expf: | |||
3357 | case LibFunc_expl: | |||
3358 | return Intrinsic::exp; | |||
3359 | case LibFunc_exp2: | |||
3360 | case LibFunc_exp2f: | |||
3361 | case LibFunc_exp2l: | |||
3362 | return Intrinsic::exp2; | |||
3363 | case LibFunc_log: | |||
3364 | case LibFunc_logf: | |||
3365 | case LibFunc_logl: | |||
3366 | return Intrinsic::log; | |||
3367 | case LibFunc_log10: | |||
3368 | case LibFunc_log10f: | |||
3369 | case LibFunc_log10l: | |||
3370 | return Intrinsic::log10; | |||
3371 | case LibFunc_log2: | |||
3372 | case LibFunc_log2f: | |||
3373 | case LibFunc_log2l: | |||
3374 | return Intrinsic::log2; | |||
3375 | case LibFunc_fabs: | |||
3376 | case LibFunc_fabsf: | |||
3377 | case LibFunc_fabsl: | |||
3378 | return Intrinsic::fabs; | |||
3379 | case LibFunc_fmin: | |||
3380 | case LibFunc_fminf: | |||
3381 | case LibFunc_fminl: | |||
3382 | return Intrinsic::minnum; | |||
3383 | case LibFunc_fmax: | |||
3384 | case LibFunc_fmaxf: | |||
3385 | case LibFunc_fmaxl: | |||
3386 | return Intrinsic::maxnum; | |||
3387 | case LibFunc_copysign: | |||
3388 | case LibFunc_copysignf: | |||
3389 | case LibFunc_copysignl: | |||
3390 | return Intrinsic::copysign; | |||
3391 | case LibFunc_floor: | |||
3392 | case LibFunc_floorf: | |||
3393 | case LibFunc_floorl: | |||
3394 | return Intrinsic::floor; | |||
3395 | case LibFunc_ceil: | |||
3396 | case LibFunc_ceilf: | |||
3397 | case LibFunc_ceill: | |||
3398 | return Intrinsic::ceil; | |||
3399 | case LibFunc_trunc: | |||
3400 | case LibFunc_truncf: | |||
3401 | case LibFunc_truncl: | |||
3402 | return Intrinsic::trunc; | |||
3403 | case LibFunc_rint: | |||
3404 | case LibFunc_rintf: | |||
3405 | case LibFunc_rintl: | |||
3406 | return Intrinsic::rint; | |||
3407 | case LibFunc_nearbyint: | |||
3408 | case LibFunc_nearbyintf: | |||
3409 | case LibFunc_nearbyintl: | |||
3410 | return Intrinsic::nearbyint; | |||
3411 | case LibFunc_round: | |||
3412 | case LibFunc_roundf: | |||
3413 | case LibFunc_roundl: | |||
3414 | return Intrinsic::round; | |||
3415 | case LibFunc_roundeven: | |||
3416 | case LibFunc_roundevenf: | |||
3417 | case LibFunc_roundevenl: | |||
3418 | return Intrinsic::roundeven; | |||
3419 | case LibFunc_pow: | |||
3420 | case LibFunc_powf: | |||
3421 | case LibFunc_powl: | |||
3422 | return Intrinsic::pow; | |||
3423 | case LibFunc_sqrt: | |||
3424 | case LibFunc_sqrtf: | |||
3425 | case LibFunc_sqrtl: | |||
3426 | return Intrinsic::sqrt; | |||
3427 | } | |||
3428 | ||||
3429 | return Intrinsic::not_intrinsic; | |||
3430 | } | |||
3431 | ||||
3432 | /// Return true if we can prove that the specified FP value is never equal to | |||
3433 | /// -0.0. | |||
3434 | /// NOTE: Do not check 'nsz' here because that fast-math-flag does not guarantee | |||
3435 | /// that a value is not -0.0. It only guarantees that -0.0 may be treated | |||
3436 | /// the same as +0.0 in floating-point ops. | |||
3437 | /// | |||
3438 | /// NOTE: this function will need to be revisited when we support non-default | |||
3439 | /// rounding modes! | |||
3440 | bool llvm::CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI, | |||
3441 | unsigned Depth) { | |||
3442 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
3443 | return !CFP->getValueAPF().isNegZero(); | |||
3444 | ||||
3445 | if (Depth == MaxAnalysisRecursionDepth) | |||
3446 | return false; | |||
3447 | ||||
3448 | auto *Op = dyn_cast<Operator>(V); | |||
3449 | if (!Op) | |||
3450 | return false; | |||
3451 | ||||
3452 | // (fadd x, 0.0) is guaranteed to return +0.0, not -0.0. | |||
3453 | if (match(Op, m_FAdd(m_Value(), m_PosZeroFP()))) | |||
3454 | return true; | |||
3455 | ||||
3456 | // sitofp and uitofp turn into +0.0 for zero. | |||
3457 | if (isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) | |||
3458 | return true; | |||
3459 | ||||
3460 | if (auto *Call = dyn_cast<CallInst>(Op)) { | |||
3461 | Intrinsic::ID IID = getIntrinsicForCallSite(*Call, TLI); | |||
3462 | switch (IID) { | |||
3463 | default: | |||
3464 | break; | |||
3465 | // sqrt(-0.0) = -0.0, no other negative results are possible. | |||
3466 | case Intrinsic::sqrt: | |||
3467 | case Intrinsic::canonicalize: | |||
3468 | return CannotBeNegativeZero(Call->getArgOperand(0), TLI, Depth + 1); | |||
3469 | // fabs(x) != -0.0 | |||
3470 | case Intrinsic::fabs: | |||
3471 | return true; | |||
3472 | } | |||
3473 | } | |||
3474 | ||||
3475 | return false; | |||
3476 | } | |||
3477 | ||||
3478 | /// If \p SignBitOnly is true, test for a known 0 sign bit rather than a | |||
3479 | /// standard ordered compare. e.g. make -0.0 olt 0.0 be true because of the sign | |||
3480 | /// bit despite comparing equal. | |||
3481 | static bool cannotBeOrderedLessThanZeroImpl(const Value *V, | |||
3482 | const TargetLibraryInfo *TLI, | |||
3483 | bool SignBitOnly, | |||
3484 | unsigned Depth) { | |||
3485 | // TODO: This function does not do the right thing when SignBitOnly is true | |||
3486 | // and we're lowering to a hypothetical IEEE 754-compliant-but-evil platform | |||
3487 | // which flips the sign bits of NaNs. See | |||
3488 | // https://llvm.org/bugs/show_bug.cgi?id=31702. | |||
3489 | ||||
3490 | if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { | |||
3491 | return !CFP->getValueAPF().isNegative() || | |||
3492 | (!SignBitOnly && CFP->getValueAPF().isZero()); | |||
3493 | } | |||
3494 | ||||
3495 | // Handle vector of constants. | |||
3496 | if (auto *CV = dyn_cast<Constant>(V)) { | |||
3497 | if (auto *CVFVTy = dyn_cast<FixedVectorType>(CV->getType())) { | |||
3498 | unsigned NumElts = CVFVTy->getNumElements(); | |||
3499 | for (unsigned i = 0; i != NumElts; ++i) { | |||
3500 | auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i)); | |||
3501 | if (!CFP) | |||
3502 | return false; | |||
3503 | if (CFP->getValueAPF().isNegative() && | |||
3504 | (SignBitOnly || !CFP->getValueAPF().isZero())) | |||
3505 | return false; | |||
3506 | } | |||
3507 | ||||
3508 | // All non-negative ConstantFPs. | |||
3509 | return true; | |||
3510 | } | |||
3511 | } | |||
3512 | ||||
3513 | if (Depth == MaxAnalysisRecursionDepth) | |||
3514 | return false; | |||
3515 | ||||
3516 | const Operator *I = dyn_cast<Operator>(V); | |||
3517 | if (!I) | |||
3518 | return false; | |||
3519 | ||||
3520 | switch (I->getOpcode()) { | |||
3521 | default: | |||
3522 | break; | |||
3523 | // Unsigned integers are always nonnegative. | |||
3524 | case Instruction::UIToFP: | |||
3525 | return true; | |||
3526 | case Instruction::FMul: | |||
3527 | case Instruction::FDiv: | |||
3528 | // X * X is always non-negative or a NaN. | |||
3529 | // X / X is always exactly 1.0 or a NaN. | |||
3530 | if (I->getOperand(0) == I->getOperand(1) && | |||
3531 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs())) | |||
3532 | return true; | |||
3533 | ||||
3534 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
3535 | case Instruction::FAdd: | |||
3536 | case Instruction::FRem: | |||
3537 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3538 | Depth + 1) && | |||
3539 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3540 | Depth + 1); | |||
3541 | case Instruction::Select: | |||
3542 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3543 | Depth + 1) && | |||
3544 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, | |||
3545 | Depth + 1); | |||
3546 | case Instruction::FPExt: | |||
3547 | case Instruction::FPTrunc: | |||
3548 | // Widening/narrowing never change sign. | |||
3549 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3550 | Depth + 1); | |||
3551 | case Instruction::ExtractElement: | |||
3552 | // Look through extract element. At the moment we keep this simple and skip | |||
3553 | // tracking the specific element. But at least we might find information | |||
3554 | // valid for all elements of the vector. | |||
3555 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3556 | Depth + 1); | |||
3557 | case Instruction::Call: | |||
3558 | const auto *CI = cast<CallInst>(I); | |||
3559 | Intrinsic::ID IID = getIntrinsicForCallSite(*CI, TLI); | |||
3560 | switch (IID) { | |||
3561 | default: | |||
3562 | break; | |||
3563 | case Intrinsic::maxnum: { | |||
3564 | Value *V0 = I->getOperand(0), *V1 = I->getOperand(1); | |||
3565 | auto isPositiveNum = [&](Value *V) { | |||
3566 | if (SignBitOnly) { | |||
3567 | // With SignBitOnly, this is tricky because the result of | |||
3568 | // maxnum(+0.0, -0.0) is unspecified. Just check if the operand is | |||
3569 | // a constant strictly greater than 0.0. | |||
3570 | const APFloat *C; | |||
3571 | return match(V, m_APFloat(C)) && | |||
3572 | *C > APFloat::getZero(C->getSemantics()); | |||
3573 | } | |||
3574 | ||||
3575 | // -0.0 compares equal to 0.0, so if this operand is at least -0.0, | |||
3576 | // maxnum can't be ordered-less-than-zero. | |||
3577 | return isKnownNeverNaN(V, TLI) && | |||
3578 | cannotBeOrderedLessThanZeroImpl(V, TLI, false, Depth + 1); | |||
3579 | }; | |||
3580 | ||||
3581 | // TODO: This could be improved. We could also check that neither operand | |||
3582 | // has its sign bit set (and at least 1 is not-NAN?). | |||
3583 | return isPositiveNum(V0) || isPositiveNum(V1); | |||
3584 | } | |||
3585 | ||||
3586 | case Intrinsic::maximum: | |||
3587 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3588 | Depth + 1) || | |||
3589 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3590 | Depth + 1); | |||
3591 | case Intrinsic::minnum: | |||
3592 | case Intrinsic::minimum: | |||
3593 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3594 | Depth + 1) && | |||
3595 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3596 | Depth + 1); | |||
3597 | case Intrinsic::exp: | |||
3598 | case Intrinsic::exp2: | |||
3599 | case Intrinsic::fabs: | |||
3600 | return true; | |||
3601 | ||||
3602 | case Intrinsic::sqrt: | |||
3603 | // sqrt(x) is always >= -0 or NaN. Moreover, sqrt(x) == -0 iff x == -0. | |||
3604 | if (!SignBitOnly) | |||
3605 | return true; | |||
3606 | return CI->hasNoNaNs() && (CI->hasNoSignedZeros() || | |||
3607 | CannotBeNegativeZero(CI->getOperand(0), TLI)); | |||
3608 | ||||
3609 | case Intrinsic::powi: | |||
3610 | if (ConstantInt *Exponent = dyn_cast<ConstantInt>(I->getOperand(1))) { | |||
3611 | // powi(x,n) is non-negative if n is even. | |||
3612 | if (Exponent->getBitWidth() <= 64 && Exponent->getSExtValue() % 2u == 0) | |||
3613 | return true; | |||
3614 | } | |||
3615 | // TODO: This is not correct. Given that exp is an integer, here are the | |||
3616 | // ways that pow can return a negative value: | |||
3617 | // | |||
3618 | // pow(x, exp) --> negative if exp is odd and x is negative. | |||
3619 | // pow(-0, exp) --> -inf if exp is negative odd. | |||
3620 | // pow(-0, exp) --> -0 if exp is positive odd. | |||
3621 | // pow(-inf, exp) --> -0 if exp is negative odd. | |||
3622 | // pow(-inf, exp) --> -inf if exp is positive odd. | |||
3623 | // | |||
3624 | // Therefore, if !SignBitOnly, we can return true if x >= +0 or x is NaN, | |||
3625 | // but we must return false if x == -0. Unfortunately we do not currently | |||
3626 | // have a way of expressing this constraint. See details in | |||
3627 | // https://llvm.org/bugs/show_bug.cgi?id=31702. | |||
3628 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3629 | Depth + 1); | |||
3630 | ||||
3631 | case Intrinsic::fma: | |||
3632 | case Intrinsic::fmuladd: | |||
3633 | // x*x+y is non-negative if y is non-negative. | |||
3634 | return I->getOperand(0) == I->getOperand(1) && | |||
3635 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()) && | |||
3636 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, | |||
3637 | Depth + 1); | |||
3638 | } | |||
3639 | break; | |||
3640 | } | |||
3641 | return false; | |||
3642 | } | |||
3643 | ||||
3644 | bool llvm::CannotBeOrderedLessThanZero(const Value *V, | |||
3645 | const TargetLibraryInfo *TLI) { | |||
3646 | return cannotBeOrderedLessThanZeroImpl(V, TLI, false, 0); | |||
3647 | } | |||
3648 | ||||
3649 | bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) { | |||
3650 | return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0); | |||
3651 | } | |||
3652 | ||||
3653 | bool llvm::isKnownNeverInfinity(const Value *V, const TargetLibraryInfo *TLI, | |||
3654 | unsigned Depth) { | |||
3655 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3655, __extension__ __PRETTY_FUNCTION__)); | |||
3656 | ||||
3657 | // If we're told that infinities won't happen, assume they won't. | |||
3658 | if (auto *FPMathOp = dyn_cast<FPMathOperator>(V)) | |||
3659 | if (FPMathOp->hasNoInfs()) | |||
3660 | return true; | |||
3661 | ||||
3662 | // Handle scalar constants. | |||
3663 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
3664 | return !CFP->isInfinity(); | |||
3665 | ||||
3666 | if (Depth == MaxAnalysisRecursionDepth) | |||
3667 | return false; | |||
3668 | ||||
3669 | if (auto *Inst = dyn_cast<Instruction>(V)) { | |||
3670 | switch (Inst->getOpcode()) { | |||
3671 | case Instruction::Select: { | |||
3672 | return isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1) && | |||
3673 | isKnownNeverInfinity(Inst->getOperand(2), TLI, Depth + 1); | |||
3674 | } | |||
3675 | case Instruction::SIToFP: | |||
3676 | case Instruction::UIToFP: { | |||
3677 | // Get width of largest magnitude integer (remove a bit if signed). | |||
3678 | // This still works for a signed minimum value because the largest FP | |||
3679 | // value is scaled by some fraction close to 2.0 (1.0 + 0.xxxx). | |||
3680 | int IntSize = Inst->getOperand(0)->getType()->getScalarSizeInBits(); | |||
3681 | if (Inst->getOpcode() == Instruction::SIToFP) | |||
3682 | --IntSize; | |||
3683 | ||||
3684 | // If the exponent of the largest finite FP value can hold the largest | |||
3685 | // integer, the result of the cast must be finite. | |||
3686 | Type *FPTy = Inst->getType()->getScalarType(); | |||
3687 | return ilogb(APFloat::getLargest(FPTy->getFltSemantics())) >= IntSize; | |||
3688 | } | |||
3689 | default: | |||
3690 | break; | |||
3691 | } | |||
3692 | } | |||
3693 | ||||
3694 | // try to handle fixed width vector constants | |||
3695 | auto *VFVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
3696 | if (VFVTy && isa<Constant>(V)) { | |||
3697 | // For vectors, verify that each element is not infinity. | |||
3698 | unsigned NumElts = VFVTy->getNumElements(); | |||
3699 | for (unsigned i = 0; i != NumElts; ++i) { | |||
3700 | Constant *Elt = cast<Constant>(V)->getAggregateElement(i); | |||
3701 | if (!Elt) | |||
3702 | return false; | |||
3703 | if (isa<UndefValue>(Elt)) | |||
3704 | continue; | |||
3705 | auto *CElt = dyn_cast<ConstantFP>(Elt); | |||
3706 | if (!CElt || CElt->isInfinity()) | |||
3707 | return false; | |||
3708 | } | |||
3709 | // All elements were confirmed non-infinity or undefined. | |||
3710 | return true; | |||
3711 | } | |||
3712 | ||||
3713 | // was not able to prove that V never contains infinity | |||
3714 | return false; | |||
3715 | } | |||
3716 | ||||
3717 | bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI, | |||
3718 | unsigned Depth) { | |||
3719 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3719, __extension__ __PRETTY_FUNCTION__)); | |||
3720 | ||||
3721 | // If we're told that NaNs won't happen, assume they won't. | |||
3722 | if (auto *FPMathOp = dyn_cast<FPMathOperator>(V)) | |||
3723 | if (FPMathOp->hasNoNaNs()) | |||
3724 | return true; | |||
3725 | ||||
3726 | // Handle scalar constants. | |||
3727 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
3728 | return !CFP->isNaN(); | |||
3729 | ||||
3730 | if (Depth == MaxAnalysisRecursionDepth) | |||
3731 | return false; | |||
3732 | ||||
3733 | if (auto *Inst = dyn_cast<Instruction>(V)) { | |||
3734 | switch (Inst->getOpcode()) { | |||
3735 | case Instruction::FAdd: | |||
3736 | case Instruction::FSub: | |||
3737 | // Adding positive and negative infinity produces NaN. | |||
3738 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) && | |||
3739 | isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && | |||
3740 | (isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) || | |||
3741 | isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1)); | |||
3742 | ||||
3743 | case Instruction::FMul: | |||
3744 | // Zero multiplied with infinity produces NaN. | |||
3745 | // FIXME: If neither side can be zero fmul never produces NaN. | |||
3746 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) && | |||
3747 | isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) && | |||
3748 | isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && | |||
3749 | isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1); | |||
3750 | ||||
3751 | case Instruction::FDiv: | |||
3752 | case Instruction::FRem: | |||
3753 | // FIXME: Only 0/0, Inf/Inf, Inf REM x and x REM 0 produce NaN. | |||
3754 | return false; | |||
3755 | ||||
3756 | case Instruction::Select: { | |||
3757 | return isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && | |||
3758 | isKnownNeverNaN(Inst->getOperand(2), TLI, Depth + 1); | |||
3759 | } | |||
3760 | case Instruction::SIToFP: | |||
3761 | case Instruction::UIToFP: | |||
3762 | return true; | |||
3763 | case Instruction::FPTrunc: | |||
3764 | case Instruction::FPExt: | |||
3765 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1); | |||
3766 | default: | |||
3767 | break; | |||
3768 | } | |||
3769 | } | |||
3770 | ||||
3771 | if (const auto *II = dyn_cast<IntrinsicInst>(V)) { | |||
3772 | switch (II->getIntrinsicID()) { | |||
3773 | case Intrinsic::canonicalize: | |||
3774 | case Intrinsic::fabs: | |||
3775 | case Intrinsic::copysign: | |||
3776 | case Intrinsic::exp: | |||
3777 | case Intrinsic::exp2: | |||
3778 | case Intrinsic::floor: | |||
3779 | case Intrinsic::ceil: | |||
3780 | case Intrinsic::trunc: | |||
3781 | case Intrinsic::rint: | |||
3782 | case Intrinsic::nearbyint: | |||
3783 | case Intrinsic::round: | |||
3784 | case Intrinsic::roundeven: | |||
3785 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1); | |||
3786 | case Intrinsic::sqrt: | |||
3787 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) && | |||
3788 | CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI); | |||
3789 | case Intrinsic::minnum: | |||
3790 | case Intrinsic::maxnum: | |||
3791 | // If either operand is not NaN, the result is not NaN. | |||
3792 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) || | |||
3793 | isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1); | |||
3794 | default: | |||
3795 | return false; | |||
3796 | } | |||
3797 | } | |||
3798 | ||||
3799 | // Try to handle fixed width vector constants | |||
3800 | auto *VFVTy = dyn_cast<FixedVectorType>(V->getType()); | |||
3801 | if (VFVTy && isa<Constant>(V)) { | |||
3802 | // For vectors, verify that each element is not NaN. | |||
3803 | unsigned NumElts = VFVTy->getNumElements(); | |||
3804 | for (unsigned i = 0; i != NumElts; ++i) { | |||
3805 | Constant *Elt = cast<Constant>(V)->getAggregateElement(i); | |||
3806 | if (!Elt) | |||
3807 | return false; | |||
3808 | if (isa<UndefValue>(Elt)) | |||
3809 | continue; | |||
3810 | auto *CElt = dyn_cast<ConstantFP>(Elt); | |||
3811 | if (!CElt || CElt->isNaN()) | |||
3812 | return false; | |||
3813 | } | |||
3814 | // All elements were confirmed not-NaN or undefined. | |||
3815 | return true; | |||
3816 | } | |||
3817 | ||||
3818 | // Was not able to prove that V never contains NaN | |||
3819 | return false; | |||
3820 | } | |||
3821 | ||||
3822 | Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) { | |||
3823 | ||||
3824 | // All byte-wide stores are splatable, even of arbitrary variables. | |||
3825 | if (V->getType()->isIntegerTy(8)) | |||
3826 | return V; | |||
3827 | ||||
3828 | LLVMContext &Ctx = V->getContext(); | |||
3829 | ||||
3830 | // Undef don't care. | |||
3831 | auto *UndefInt8 = UndefValue::get(Type::getInt8Ty(Ctx)); | |||
3832 | if (isa<UndefValue>(V)) | |||
3833 | return UndefInt8; | |||
3834 | ||||
3835 | // Return Undef for zero-sized type. | |||
3836 | if (!DL.getTypeStoreSize(V->getType()).isNonZero()) | |||
3837 | return UndefInt8; | |||
3838 | ||||
3839 | Constant *C = dyn_cast<Constant>(V); | |||
3840 | if (!C) { | |||
3841 | // Conceptually, we could handle things like: | |||
3842 | // %a = zext i8 %X to i16 | |||
3843 | // %b = shl i16 %a, 8 | |||
3844 | // %c = or i16 %a, %b | |||
3845 | // but until there is an example that actually needs this, it doesn't seem | |||
3846 | // worth worrying about. | |||
3847 | return nullptr; | |||
3848 | } | |||
3849 | ||||
3850 | // Handle 'null' ConstantArrayZero etc. | |||
3851 | if (C->isNullValue()) | |||
3852 | return Constant::getNullValue(Type::getInt8Ty(Ctx)); | |||
3853 | ||||
3854 | // Constant floating-point values can be handled as integer values if the | |||
3855 | // corresponding integer value is "byteable". An important case is 0.0. | |||
3856 | if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) { | |||
3857 | Type *Ty = nullptr; | |||
3858 | if (CFP->getType()->isHalfTy()) | |||
3859 | Ty = Type::getInt16Ty(Ctx); | |||
3860 | else if (CFP->getType()->isFloatTy()) | |||
3861 | Ty = Type::getInt32Ty(Ctx); | |||
3862 | else if (CFP->getType()->isDoubleTy()) | |||
3863 | Ty = Type::getInt64Ty(Ctx); | |||
3864 | // Don't handle long double formats, which have strange constraints. | |||
3865 | return Ty ? isBytewiseValue(ConstantExpr::getBitCast(CFP, Ty), DL) | |||
3866 | : nullptr; | |||
3867 | } | |||
3868 | ||||
3869 | // We can handle constant integers that are multiple of 8 bits. | |||
3870 | if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { | |||
3871 | if (CI->getBitWidth() % 8 == 0) { | |||
3872 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3872, __extension__ __PRETTY_FUNCTION__)); | |||
3873 | if (!CI->getValue().isSplat(8)) | |||
3874 | return nullptr; | |||
3875 | return ConstantInt::get(Ctx, CI->getValue().trunc(8)); | |||
3876 | } | |||
3877 | } | |||
3878 | ||||
3879 | if (auto *CE = dyn_cast<ConstantExpr>(C)) { | |||
3880 | if (CE->getOpcode() == Instruction::IntToPtr) { | |||
3881 | if (auto *PtrTy = dyn_cast<PointerType>(CE->getType())) { | |||
3882 | unsigned BitWidth = DL.getPointerSizeInBits(PtrTy->getAddressSpace()); | |||
3883 | return isBytewiseValue( | |||
3884 | ConstantExpr::getIntegerCast(CE->getOperand(0), | |||
3885 | Type::getIntNTy(Ctx, BitWidth), false), | |||
3886 | DL); | |||
3887 | } | |||
3888 | } | |||
3889 | } | |||
3890 | ||||
3891 | auto Merge = [&](Value *LHS, Value *RHS) -> Value * { | |||
3892 | if (LHS == RHS) | |||
3893 | return LHS; | |||
3894 | if (!LHS || !RHS) | |||
3895 | return nullptr; | |||
3896 | if (LHS == UndefInt8) | |||
3897 | return RHS; | |||
3898 | if (RHS == UndefInt8) | |||
3899 | return LHS; | |||
3900 | return nullptr; | |||
3901 | }; | |||
3902 | ||||
3903 | if (ConstantDataSequential *CA = dyn_cast<ConstantDataSequential>(C)) { | |||
3904 | Value *Val = UndefInt8; | |||
3905 | for (unsigned I = 0, E = CA->getNumElements(); I != E; ++I) | |||
3906 | if (!(Val = Merge(Val, isBytewiseValue(CA->getElementAsConstant(I), DL)))) | |||
3907 | return nullptr; | |||
3908 | return Val; | |||
3909 | } | |||
3910 | ||||
3911 | if (isa<ConstantAggregate>(C)) { | |||
3912 | Value *Val = UndefInt8; | |||
3913 | for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) | |||
3914 | if (!(Val = Merge(Val, isBytewiseValue(C->getOperand(I), DL)))) | |||
3915 | return nullptr; | |||
3916 | return Val; | |||
3917 | } | |||
3918 | ||||
3919 | // Don't try to handle the handful of other constants. | |||
3920 | return nullptr; | |||
3921 | } | |||
3922 | ||||
3923 | // This is the recursive version of BuildSubAggregate. It takes a few different | |||
3924 | // arguments. Idxs is the index within the nested struct From that we are | |||
3925 | // looking at now (which is of type IndexedType). IdxSkip is the number of | |||
3926 | // indices from Idxs that should be left out when inserting into the resulting | |||
3927 | // struct. To is the result struct built so far, new insertvalue instructions | |||
3928 | // build on that. | |||
3929 | static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType, | |||
3930 | SmallVectorImpl<unsigned> &Idxs, | |||
3931 | unsigned IdxSkip, | |||
3932 | Instruction *InsertBefore) { | |||
3933 | StructType *STy = dyn_cast<StructType>(IndexedType); | |||
3934 | if (STy) { | |||
3935 | // Save the original To argument so we can modify it | |||
3936 | Value *OrigTo = To; | |||
3937 | // General case, the type indexed by Idxs is a struct | |||
3938 | for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { | |||
3939 | // Process each struct element recursively | |||
3940 | Idxs.push_back(i); | |||
3941 | Value *PrevTo = To; | |||
3942 | To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, | |||
3943 | InsertBefore); | |||
3944 | Idxs.pop_back(); | |||
3945 | if (!To) { | |||
3946 | // Couldn't find any inserted value for this index? Cleanup | |||
3947 | while (PrevTo != OrigTo) { | |||
3948 | InsertValueInst* Del = cast<InsertValueInst>(PrevTo); | |||
3949 | PrevTo = Del->getAggregateOperand(); | |||
3950 | Del->eraseFromParent(); | |||
3951 | } | |||
3952 | // Stop processing elements | |||
3953 | break; | |||
3954 | } | |||
3955 | } | |||
3956 | // If we successfully found a value for each of our subaggregates | |||
3957 | if (To) | |||
3958 | return To; | |||
3959 | } | |||
3960 | // Base case, the type indexed by SourceIdxs is not a struct, or not all of | |||
3961 | // the struct's elements had a value that was inserted directly. In the latter | |||
3962 | // case, perhaps we can't determine each of the subelements individually, but | |||
3963 | // we might be able to find the complete struct somewhere. | |||
3964 | ||||
3965 | // Find the value that is at that particular spot | |||
3966 | Value *V = FindInsertedValue(From, Idxs); | |||
3967 | ||||
3968 | if (!V) | |||
3969 | return nullptr; | |||
3970 | ||||
3971 | // Insert the value in the new (sub) aggregate | |||
3972 | return InsertValueInst::Create(To, V, makeArrayRef(Idxs).slice(IdxSkip), | |||
3973 | "tmp", InsertBefore); | |||
3974 | } | |||
3975 | ||||
3976 | // This helper takes a nested struct and extracts a part of it (which is again a | |||
3977 | // struct) into a new value. For example, given the struct: | |||
3978 | // { a, { b, { c, d }, e } } | |||
3979 | // and the indices "1, 1" this returns | |||
3980 | // { c, d }. | |||
3981 | // | |||
3982 | // It does this by inserting an insertvalue for each element in the resulting | |||
3983 | // struct, as opposed to just inserting a single struct. This will only work if | |||
3984 | // each of the elements of the substruct are known (ie, inserted into From by an | |||
3985 | // insertvalue instruction somewhere). | |||
3986 | // | |||
3987 | // All inserted insertvalue instructions are inserted before InsertBefore | |||
3988 | static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range, | |||
3989 | Instruction *InsertBefore) { | |||
3990 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 3990, __extension__ __PRETTY_FUNCTION__)); | |||
3991 | Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), | |||
3992 | idx_range); | |||
3993 | Value *To = UndefValue::get(IndexedType); | |||
3994 | SmallVector<unsigned, 10> Idxs(idx_range.begin(), idx_range.end()); | |||
3995 | unsigned IdxSkip = Idxs.size(); | |||
3996 | ||||
3997 | return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); | |||
3998 | } | |||
3999 | ||||
4000 | /// Given an aggregate and a sequence of indices, see if the scalar value | |||
4001 | /// indexed is already around as a register, for example if it was inserted | |||
4002 | /// directly into the aggregate. | |||
4003 | /// | |||
4004 | /// If InsertBefore is not null, this function will duplicate (modified) | |||
4005 | /// insertvalues when a part of a nested struct is extracted. | |||
4006 | Value *llvm::FindInsertedValue(Value *V, ArrayRef<unsigned> idx_range, | |||
4007 | Instruction *InsertBefore) { | |||
4008 | // Nothing to index? Just return V then (this is useful at the end of our | |||
4009 | // recursion). | |||
4010 | if (idx_range.empty()) | |||
4011 | return V; | |||
4012 | // We have indices, so V should have an indexable type. | |||
4013 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4014, __extension__ __PRETTY_FUNCTION__)) | |||
4014 | "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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4014, __extension__ __PRETTY_FUNCTION__)); | |||
4015 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4016, __extension__ __PRETTY_FUNCTION__)) | |||
4016 | "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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4016, __extension__ __PRETTY_FUNCTION__)); | |||
4017 | ||||
4018 | if (Constant *C = dyn_cast<Constant>(V)) { | |||
4019 | C = C->getAggregateElement(idx_range[0]); | |||
4020 | if (!C) return nullptr; | |||
4021 | return FindInsertedValue(C, idx_range.slice(1), InsertBefore); | |||
4022 | } | |||
4023 | ||||
4024 | if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) { | |||
4025 | // Loop the indices for the insertvalue instruction in parallel with the | |||
4026 | // requested indices | |||
4027 | const unsigned *req_idx = idx_range.begin(); | |||
4028 | for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); | |||
4029 | i != e; ++i, ++req_idx) { | |||
4030 | if (req_idx == idx_range.end()) { | |||
4031 | // We can't handle this without inserting insertvalues | |||
4032 | if (!InsertBefore) | |||
4033 | return nullptr; | |||
4034 | ||||
4035 | // The requested index identifies a part of a nested aggregate. Handle | |||
4036 | // this specially. For example, | |||
4037 | // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0 | |||
4038 | // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1 | |||
4039 | // %C = extractvalue {i32, { i32, i32 } } %B, 1 | |||
4040 | // This can be changed into | |||
4041 | // %A = insertvalue {i32, i32 } undef, i32 10, 0 | |||
4042 | // %C = insertvalue {i32, i32 } %A, i32 11, 1 | |||
4043 | // which allows the unused 0,0 element from the nested struct to be | |||
4044 | // removed. | |||
4045 | return BuildSubAggregate(V, makeArrayRef(idx_range.begin(), req_idx), | |||
4046 | InsertBefore); | |||
4047 | } | |||
4048 | ||||
4049 | // This insert value inserts something else than what we are looking for. | |||
4050 | // See if the (aggregate) value inserted into has the value we are | |||
4051 | // looking for, then. | |||
4052 | if (*req_idx != *i) | |||
4053 | return FindInsertedValue(I->getAggregateOperand(), idx_range, | |||
4054 | InsertBefore); | |||
4055 | } | |||
4056 | // If we end up here, the indices of the insertvalue match with those | |||
4057 | // requested (though possibly only partially). Now we recursively look at | |||
4058 | // the inserted value, passing any remaining indices. | |||
4059 | return FindInsertedValue(I->getInsertedValueOperand(), | |||
4060 | makeArrayRef(req_idx, idx_range.end()), | |||
4061 | InsertBefore); | |||
4062 | } | |||
4063 | ||||
4064 | if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) { | |||
4065 | // If we're extracting a value from an aggregate that was extracted from | |||
4066 | // something else, we can extract from that something else directly instead. | |||
4067 | // However, we will need to chain I's indices with the requested indices. | |||
4068 | ||||
4069 | // Calculate the number of indices required | |||
4070 | unsigned size = I->getNumIndices() + idx_range.size(); | |||
4071 | // Allocate some space to put the new indices in | |||
4072 | SmallVector<unsigned, 5> Idxs; | |||
4073 | Idxs.reserve(size); | |||
4074 | // Add indices from the extract value instruction | |||
4075 | Idxs.append(I->idx_begin(), I->idx_end()); | |||
4076 | ||||
4077 | // Add requested indices | |||
4078 | Idxs.append(idx_range.begin(), idx_range.end()); | |||
4079 | ||||
4080 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4081, __extension__ __PRETTY_FUNCTION__)) | |||
4081 | && "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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4081, __extension__ __PRETTY_FUNCTION__)); | |||
4082 | ||||
4083 | return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore); | |||
4084 | } | |||
4085 | // Otherwise, we don't know (such as, extracting from a function return value | |||
4086 | // or load instruction) | |||
4087 | return nullptr; | |||
4088 | } | |||
4089 | ||||
4090 | bool llvm::isGEPBasedOnPointerToString(const GEPOperator *GEP, | |||
4091 | unsigned CharSize) { | |||
4092 | // Make sure the GEP has exactly three arguments. | |||
4093 | if (GEP->getNumOperands() != 3) | |||
4094 | return false; | |||
4095 | ||||
4096 | // Make sure the index-ee is a pointer to array of \p CharSize integers. | |||
4097 | // CharSize. | |||
4098 | ArrayType *AT = dyn_cast<ArrayType>(GEP->getSourceElementType()); | |||
4099 | if (!AT || !AT->getElementType()->isIntegerTy(CharSize)) | |||
4100 | return false; | |||
4101 | ||||
4102 | // Check to make sure that the first operand of the GEP is an integer and | |||
4103 | // has value 0 so that we are sure we're indexing into the initializer. | |||
4104 | const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1)); | |||
4105 | if (!FirstIdx || !FirstIdx->isZero()) | |||
4106 | return false; | |||
4107 | ||||
4108 | return true; | |||
4109 | } | |||
4110 | ||||
4111 | bool llvm::getConstantDataArrayInfo(const Value *V, | |||
4112 | ConstantDataArraySlice &Slice, | |||
4113 | unsigned ElementSize, uint64_t Offset) { | |||
4114 | assert(V)(static_cast <bool> (V) ? void (0) : __assert_fail ("V" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4114, __extension__ __PRETTY_FUNCTION__)); | |||
4115 | ||||
4116 | // Look through bitcast instructions and geps. | |||
4117 | V = V->stripPointerCasts(); | |||
4118 | ||||
4119 | // If the value is a GEP instruction or constant expression, treat it as an | |||
4120 | // offset. | |||
4121 | if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { | |||
4122 | // The GEP operator should be based on a pointer to string constant, and is | |||
4123 | // indexing into the string constant. | |||
4124 | if (!isGEPBasedOnPointerToString(GEP, ElementSize)) | |||
4125 | return false; | |||
4126 | ||||
4127 | // If the second index isn't a ConstantInt, then this is a variable index | |||
4128 | // into the array. If this occurs, we can't say anything meaningful about | |||
4129 | // the string. | |||
4130 | uint64_t StartIdx = 0; | |||
4131 | if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) | |||
4132 | StartIdx = CI->getZExtValue(); | |||
4133 | else | |||
4134 | return false; | |||
4135 | return getConstantDataArrayInfo(GEP->getOperand(0), Slice, ElementSize, | |||
4136 | StartIdx + Offset); | |||
4137 | } | |||
4138 | ||||
4139 | // The GEP instruction, constant or instruction, must reference a global | |||
4140 | // variable that is a constant and is initialized. The referenced constant | |||
4141 | // initializer is the array that we'll use for optimization. | |||
4142 | const GlobalVariable *GV = dyn_cast<GlobalVariable>(V); | |||
4143 | if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) | |||
4144 | return false; | |||
4145 | ||||
4146 | const ConstantDataArray *Array; | |||
4147 | ArrayType *ArrayTy; | |||
4148 | if (GV->getInitializer()->isNullValue()) { | |||
4149 | Type *GVTy = GV->getValueType(); | |||
4150 | if ( (ArrayTy = dyn_cast<ArrayType>(GVTy)) ) { | |||
4151 | // A zeroinitializer for the array; there is no ConstantDataArray. | |||
4152 | Array = nullptr; | |||
4153 | } else { | |||
4154 | const DataLayout &DL = GV->getParent()->getDataLayout(); | |||
4155 | uint64_t SizeInBytes = DL.getTypeStoreSize(GVTy).getFixedSize(); | |||
4156 | uint64_t Length = SizeInBytes / (ElementSize / 8); | |||
4157 | if (Length <= Offset) | |||
4158 | return false; | |||
4159 | ||||
4160 | Slice.Array = nullptr; | |||
4161 | Slice.Offset = 0; | |||
4162 | Slice.Length = Length - Offset; | |||
4163 | return true; | |||
4164 | } | |||
4165 | } else { | |||
4166 | // This must be a ConstantDataArray. | |||
4167 | Array = dyn_cast<ConstantDataArray>(GV->getInitializer()); | |||
4168 | if (!Array) | |||
4169 | return false; | |||
4170 | ArrayTy = Array->getType(); | |||
4171 | } | |||
4172 | if (!ArrayTy->getElementType()->isIntegerTy(ElementSize)) | |||
4173 | return false; | |||
4174 | ||||
4175 | uint64_t NumElts = ArrayTy->getArrayNumElements(); | |||
4176 | if (Offset > NumElts) | |||
4177 | return false; | |||
4178 | ||||
4179 | Slice.Array = Array; | |||
4180 | Slice.Offset = Offset; | |||
4181 | Slice.Length = NumElts - Offset; | |||
4182 | return true; | |||
4183 | } | |||
4184 | ||||
4185 | /// This function computes the length of a null-terminated C string pointed to | |||
4186 | /// by V. If successful, it returns true and returns the string in Str. | |||
4187 | /// If unsuccessful, it returns false. | |||
4188 | bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, | |||
4189 | uint64_t Offset, bool TrimAtNul) { | |||
4190 | ConstantDataArraySlice Slice; | |||
4191 | if (!getConstantDataArrayInfo(V, Slice, 8, Offset)) | |||
4192 | return false; | |||
4193 | ||||
4194 | if (Slice.Array == nullptr) { | |||
4195 | if (TrimAtNul) { | |||
4196 | Str = StringRef(); | |||
4197 | return true; | |||
4198 | } | |||
4199 | if (Slice.Length == 1) { | |||
4200 | Str = StringRef("", 1); | |||
4201 | return true; | |||
4202 | } | |||
4203 | // We cannot instantiate a StringRef as we do not have an appropriate string | |||
4204 | // of 0s at hand. | |||
4205 | return false; | |||
4206 | } | |||
4207 | ||||
4208 | // Start out with the entire array in the StringRef. | |||
4209 | Str = Slice.Array->getAsString(); | |||
4210 | // Skip over 'offset' bytes. | |||
4211 | Str = Str.substr(Slice.Offset); | |||
4212 | ||||
4213 | if (TrimAtNul) { | |||
4214 | // Trim off the \0 and anything after it. If the array is not nul | |||
4215 | // terminated, we just return the whole end of string. The client may know | |||
4216 | // some other way that the string is length-bound. | |||
4217 | Str = Str.substr(0, Str.find('\0')); | |||
4218 | } | |||
4219 | return true; | |||
4220 | } | |||
4221 | ||||
4222 | // These next two are very similar to the above, but also look through PHI | |||
4223 | // nodes. | |||
4224 | // TODO: See if we can integrate these two together. | |||
4225 | ||||
4226 | /// If we can compute the length of the string pointed to by | |||
4227 | /// the specified pointer, return 'len+1'. If we can't, return 0. | |||
4228 | static uint64_t GetStringLengthH(const Value *V, | |||
4229 | SmallPtrSetImpl<const PHINode*> &PHIs, | |||
4230 | unsigned CharSize) { | |||
4231 | // Look through noop bitcast instructions. | |||
4232 | V = V->stripPointerCasts(); | |||
4233 | ||||
4234 | // If this is a PHI node, there are two cases: either we have already seen it | |||
4235 | // or we haven't. | |||
4236 | if (const PHINode *PN = dyn_cast<PHINode>(V)) { | |||
4237 | if (!PHIs.insert(PN).second) | |||
4238 | return ~0ULL; // already in the set. | |||
4239 | ||||
4240 | // If it was new, see if all the input strings are the same length. | |||
4241 | uint64_t LenSoFar = ~0ULL; | |||
4242 | for (Value *IncValue : PN->incoming_values()) { | |||
4243 | uint64_t Len = GetStringLengthH(IncValue, PHIs, CharSize); | |||
4244 | if (Len == 0) return 0; // Unknown length -> unknown. | |||
4245 | ||||
4246 | if (Len == ~0ULL) continue; | |||
4247 | ||||
4248 | if (Len != LenSoFar && LenSoFar != ~0ULL) | |||
4249 | return 0; // Disagree -> unknown. | |||
4250 | LenSoFar = Len; | |||
4251 | } | |||
4252 | ||||
4253 | // Success, all agree. | |||
4254 | return LenSoFar; | |||
4255 | } | |||
4256 | ||||
4257 | // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) | |||
4258 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) { | |||
4259 | uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs, CharSize); | |||
4260 | if (Len1 == 0) return 0; | |||
4261 | uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs, CharSize); | |||
4262 | if (Len2 == 0) return 0; | |||
4263 | if (Len1 == ~0ULL) return Len2; | |||
4264 | if (Len2 == ~0ULL) return Len1; | |||
4265 | if (Len1 != Len2) return 0; | |||
4266 | return Len1; | |||
4267 | } | |||
4268 | ||||
4269 | // Otherwise, see if we can read the string. | |||
4270 | ConstantDataArraySlice Slice; | |||
4271 | if (!getConstantDataArrayInfo(V, Slice, CharSize)) | |||
4272 | return 0; | |||
4273 | ||||
4274 | if (Slice.Array == nullptr) | |||
4275 | return 1; | |||
4276 | ||||
4277 | // Search for nul characters | |||
4278 | unsigned NullIndex = 0; | |||
4279 | for (unsigned E = Slice.Length; NullIndex < E; ++NullIndex) { | |||
4280 | if (Slice.Array->getElementAsInteger(Slice.Offset + NullIndex) == 0) | |||
4281 | break; | |||
4282 | } | |||
4283 | ||||
4284 | return NullIndex + 1; | |||
4285 | } | |||
4286 | ||||
4287 | /// If we can compute the length of the string pointed to by | |||
4288 | /// the specified pointer, return 'len+1'. If we can't, return 0. | |||
4289 | uint64_t llvm::GetStringLength(const Value *V, unsigned CharSize) { | |||
4290 | if (!V->getType()->isPointerTy()) | |||
4291 | return 0; | |||
4292 | ||||
4293 | SmallPtrSet<const PHINode*, 32> PHIs; | |||
4294 | uint64_t Len = GetStringLengthH(V, PHIs, CharSize); | |||
4295 | // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return | |||
4296 | // an empty string as a length. | |||
4297 | return Len == ~0ULL ? 1 : Len; | |||
4298 | } | |||
4299 | ||||
4300 | const Value * | |||
4301 | llvm::getArgumentAliasingToReturnedPointer(const CallBase *Call, | |||
4302 | bool MustPreserveNullness) { | |||
4303 | assert(Call &&(static_cast <bool> (Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls" ) ? void (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4304, __extension__ __PRETTY_FUNCTION__)) | |||
4304 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4304, __extension__ __PRETTY_FUNCTION__)); | |||
4305 | if (const Value *RV = Call->getReturnedArgOperand()) | |||
4306 | return RV; | |||
4307 | // This can be used only as a aliasing property. | |||
4308 | if (isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( | |||
4309 | Call, MustPreserveNullness)) | |||
4310 | return Call->getArgOperand(0); | |||
4311 | return nullptr; | |||
4312 | } | |||
4313 | ||||
4314 | bool llvm::isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( | |||
4315 | const CallBase *Call, bool MustPreserveNullness) { | |||
4316 | switch (Call->getIntrinsicID()) { | |||
4317 | case Intrinsic::launder_invariant_group: | |||
4318 | case Intrinsic::strip_invariant_group: | |||
4319 | case Intrinsic::aarch64_irg: | |||
4320 | case Intrinsic::aarch64_tagp: | |||
4321 | return true; | |||
4322 | case Intrinsic::ptrmask: | |||
4323 | return !MustPreserveNullness; | |||
4324 | default: | |||
4325 | return false; | |||
4326 | } | |||
4327 | } | |||
4328 | ||||
4329 | /// \p PN defines a loop-variant pointer to an object. Check if the | |||
4330 | /// previous iteration of the loop was referring to the same object as \p PN. | |||
4331 | static bool isSameUnderlyingObjectInLoop(const PHINode *PN, | |||
4332 | const LoopInfo *LI) { | |||
4333 | // Find the loop-defined value. | |||
4334 | Loop *L = LI->getLoopFor(PN->getParent()); | |||
4335 | if (PN->getNumIncomingValues() != 2) | |||
4336 | return true; | |||
4337 | ||||
4338 | // Find the value from previous iteration. | |||
4339 | auto *PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(0)); | |||
4340 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) | |||
4341 | PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(1)); | |||
4342 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) | |||
4343 | return true; | |||
4344 | ||||
4345 | // If a new pointer is loaded in the loop, the pointer references a different | |||
4346 | // object in every iteration. E.g.: | |||
4347 | // for (i) | |||
4348 | // int *p = a[i]; | |||
4349 | // ... | |||
4350 | if (auto *Load = dyn_cast<LoadInst>(PrevValue)) | |||
4351 | if (!L->isLoopInvariant(Load->getPointerOperand())) | |||
4352 | return false; | |||
4353 | return true; | |||
4354 | } | |||
4355 | ||||
4356 | const Value *llvm::getUnderlyingObject(const Value *V, unsigned MaxLookup) { | |||
4357 | if (!V->getType()->isPointerTy()) | |||
4358 | return V; | |||
4359 | for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { | |||
4360 | if (auto *GEP = dyn_cast<GEPOperator>(V)) { | |||
4361 | V = GEP->getPointerOperand(); | |||
4362 | } else if (Operator::getOpcode(V) == Instruction::BitCast || | |||
4363 | Operator::getOpcode(V) == Instruction::AddrSpaceCast) { | |||
4364 | V = cast<Operator>(V)->getOperand(0); | |||
4365 | if (!V->getType()->isPointerTy()) | |||
4366 | return V; | |||
4367 | } else if (auto *GA = dyn_cast<GlobalAlias>(V)) { | |||
4368 | if (GA->isInterposable()) | |||
4369 | return V; | |||
4370 | V = GA->getAliasee(); | |||
4371 | } else { | |||
4372 | if (auto *PHI = dyn_cast<PHINode>(V)) { | |||
4373 | // Look through single-arg phi nodes created by LCSSA. | |||
4374 | if (PHI->getNumIncomingValues() == 1) { | |||
4375 | V = PHI->getIncomingValue(0); | |||
4376 | continue; | |||
4377 | } | |||
4378 | } else if (auto *Call = dyn_cast<CallBase>(V)) { | |||
4379 | // CaptureTracking can know about special capturing properties of some | |||
4380 | // intrinsics like launder.invariant.group, that can't be expressed with | |||
4381 | // the attributes, but have properties like returning aliasing pointer. | |||
4382 | // Because some analysis may assume that nocaptured pointer is not | |||
4383 | // returned from some special intrinsic (because function would have to | |||
4384 | // be marked with returns attribute), it is crucial to use this function | |||
4385 | // because it should be in sync with CaptureTracking. Not using it may | |||
4386 | // cause weird miscompilations where 2 aliasing pointers are assumed to | |||
4387 | // noalias. | |||
4388 | if (auto *RP = getArgumentAliasingToReturnedPointer(Call, false)) { | |||
4389 | V = RP; | |||
4390 | continue; | |||
4391 | } | |||
4392 | } | |||
4393 | ||||
4394 | return V; | |||
4395 | } | |||
4396 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4396, __extension__ __PRETTY_FUNCTION__)); | |||
4397 | } | |||
4398 | return V; | |||
4399 | } | |||
4400 | ||||
4401 | void llvm::getUnderlyingObjects(const Value *V, | |||
4402 | SmallVectorImpl<const Value *> &Objects, | |||
4403 | LoopInfo *LI, unsigned MaxLookup) { | |||
4404 | SmallPtrSet<const Value *, 4> Visited; | |||
4405 | SmallVector<const Value *, 4> Worklist; | |||
4406 | Worklist.push_back(V); | |||
4407 | do { | |||
4408 | const Value *P = Worklist.pop_back_val(); | |||
4409 | P = getUnderlyingObject(P, MaxLookup); | |||
4410 | ||||
4411 | if (!Visited.insert(P).second) | |||
4412 | continue; | |||
4413 | ||||
4414 | if (auto *SI = dyn_cast<SelectInst>(P)) { | |||
4415 | Worklist.push_back(SI->getTrueValue()); | |||
4416 | Worklist.push_back(SI->getFalseValue()); | |||
4417 | continue; | |||
4418 | } | |||
4419 | ||||
4420 | if (auto *PN = dyn_cast<PHINode>(P)) { | |||
4421 | // If this PHI changes the underlying object in every iteration of the | |||
4422 | // loop, don't look through it. Consider: | |||
4423 | // int **A; | |||
4424 | // for (i) { | |||
4425 | // Prev = Curr; // Prev = PHI (Prev_0, Curr) | |||
4426 | // Curr = A[i]; | |||
4427 | // *Prev, *Curr; | |||
4428 | // | |||
4429 | // Prev is tracking Curr one iteration behind so they refer to different | |||
4430 | // underlying objects. | |||
4431 | if (!LI || !LI->isLoopHeader(PN->getParent()) || | |||
4432 | isSameUnderlyingObjectInLoop(PN, LI)) | |||
4433 | append_range(Worklist, PN->incoming_values()); | |||
4434 | continue; | |||
4435 | } | |||
4436 | ||||
4437 | Objects.push_back(P); | |||
4438 | } while (!Worklist.empty()); | |||
4439 | } | |||
4440 | ||||
4441 | /// This is the function that does the work of looking through basic | |||
4442 | /// ptrtoint+arithmetic+inttoptr sequences. | |||
4443 | static const Value *getUnderlyingObjectFromInt(const Value *V) { | |||
4444 | do { | |||
4445 | if (const Operator *U = dyn_cast<Operator>(V)) { | |||
4446 | // If we find a ptrtoint, we can transfer control back to the | |||
4447 | // regular getUnderlyingObjectFromInt. | |||
4448 | if (U->getOpcode() == Instruction::PtrToInt) | |||
4449 | return U->getOperand(0); | |||
4450 | // If we find an add of a constant, a multiplied value, or a phi, it's | |||
4451 | // likely that the other operand will lead us to the base | |||
4452 | // object. We don't have to worry about the case where the | |||
4453 | // object address is somehow being computed by the multiply, | |||
4454 | // because our callers only care when the result is an | |||
4455 | // identifiable object. | |||
4456 | if (U->getOpcode() != Instruction::Add || | |||
4457 | (!isa<ConstantInt>(U->getOperand(1)) && | |||
4458 | Operator::getOpcode(U->getOperand(1)) != Instruction::Mul && | |||
4459 | !isa<PHINode>(U->getOperand(1)))) | |||
4460 | return V; | |||
4461 | V = U->getOperand(0); | |||
4462 | } else { | |||
4463 | return V; | |||
4464 | } | |||
4465 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4465, __extension__ __PRETTY_FUNCTION__)); | |||
4466 | } while (true); | |||
4467 | } | |||
4468 | ||||
4469 | /// This is a wrapper around getUnderlyingObjects and adds support for basic | |||
4470 | /// ptrtoint+arithmetic+inttoptr sequences. | |||
4471 | /// It returns false if unidentified object is found in getUnderlyingObjects. | |||
4472 | bool llvm::getUnderlyingObjectsForCodeGen(const Value *V, | |||
4473 | SmallVectorImpl<Value *> &Objects) { | |||
4474 | SmallPtrSet<const Value *, 16> Visited; | |||
4475 | SmallVector<const Value *, 4> Working(1, V); | |||
4476 | do { | |||
4477 | V = Working.pop_back_val(); | |||
4478 | ||||
4479 | SmallVector<const Value *, 4> Objs; | |||
4480 | getUnderlyingObjects(V, Objs); | |||
4481 | ||||
4482 | for (const Value *V : Objs) { | |||
4483 | if (!Visited.insert(V).second) | |||
4484 | continue; | |||
4485 | if (Operator::getOpcode(V) == Instruction::IntToPtr) { | |||
4486 | const Value *O = | |||
4487 | getUnderlyingObjectFromInt(cast<User>(V)->getOperand(0)); | |||
4488 | if (O->getType()->isPointerTy()) { | |||
4489 | Working.push_back(O); | |||
4490 | continue; | |||
4491 | } | |||
4492 | } | |||
4493 | // If getUnderlyingObjects fails to find an identifiable object, | |||
4494 | // getUnderlyingObjectsForCodeGen also fails for safety. | |||
4495 | if (!isIdentifiedObject(V)) { | |||
4496 | Objects.clear(); | |||
4497 | return false; | |||
4498 | } | |||
4499 | Objects.push_back(const_cast<Value *>(V)); | |||
4500 | } | |||
4501 | } while (!Working.empty()); | |||
4502 | return true; | |||
4503 | } | |||
4504 | ||||
4505 | AllocaInst *llvm::findAllocaForValue(Value *V, bool OffsetZero) { | |||
4506 | AllocaInst *Result = nullptr; | |||
4507 | SmallPtrSet<Value *, 4> Visited; | |||
4508 | SmallVector<Value *, 4> Worklist; | |||
4509 | ||||
4510 | auto AddWork = [&](Value *V) { | |||
4511 | if (Visited.insert(V).second) | |||
4512 | Worklist.push_back(V); | |||
4513 | }; | |||
4514 | ||||
4515 | AddWork(V); | |||
4516 | do { | |||
4517 | V = Worklist.pop_back_val(); | |||
4518 | assert(Visited.count(V))(static_cast <bool> (Visited.count(V)) ? void (0) : __assert_fail ("Visited.count(V)", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4518, __extension__ __PRETTY_FUNCTION__)); | |||
4519 | ||||
4520 | if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) { | |||
4521 | if (Result && Result != AI) | |||
4522 | return nullptr; | |||
4523 | Result = AI; | |||
4524 | } else if (CastInst *CI = dyn_cast<CastInst>(V)) { | |||
4525 | AddWork(CI->getOperand(0)); | |||
4526 | } else if (PHINode *PN = dyn_cast<PHINode>(V)) { | |||
4527 | for (Value *IncValue : PN->incoming_values()) | |||
4528 | AddWork(IncValue); | |||
4529 | } else if (auto *SI = dyn_cast<SelectInst>(V)) { | |||
4530 | AddWork(SI->getTrueValue()); | |||
4531 | AddWork(SI->getFalseValue()); | |||
4532 | } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) { | |||
4533 | if (OffsetZero && !GEP->hasAllZeroIndices()) | |||
4534 | return nullptr; | |||
4535 | AddWork(GEP->getPointerOperand()); | |||
4536 | } else { | |||
4537 | return nullptr; | |||
4538 | } | |||
4539 | } while (!Worklist.empty()); | |||
4540 | ||||
4541 | return Result; | |||
4542 | } | |||
4543 | ||||
4544 | static bool onlyUsedByLifetimeMarkersOrDroppableInstsHelper( | |||
4545 | const Value *V, bool AllowLifetime, bool AllowDroppable) { | |||
4546 | for (const User *U : V->users()) { | |||
4547 | const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U); | |||
4548 | if (!II) | |||
4549 | return false; | |||
4550 | ||||
4551 | if (AllowLifetime && II->isLifetimeStartOrEnd()) | |||
4552 | continue; | |||
4553 | ||||
4554 | if (AllowDroppable && II->isDroppable()) | |||
4555 | continue; | |||
4556 | ||||
4557 | return false; | |||
4558 | } | |||
4559 | return true; | |||
4560 | } | |||
4561 | ||||
4562 | bool llvm::onlyUsedByLifetimeMarkers(const Value *V) { | |||
4563 | return onlyUsedByLifetimeMarkersOrDroppableInstsHelper( | |||
4564 | V, /* AllowLifetime */ true, /* AllowDroppable */ false); | |||
4565 | } | |||
4566 | bool llvm::onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V) { | |||
4567 | return onlyUsedByLifetimeMarkersOrDroppableInstsHelper( | |||
4568 | V, /* AllowLifetime */ true, /* AllowDroppable */ true); | |||
4569 | } | |||
4570 | ||||
4571 | bool llvm::mustSuppressSpeculation(const LoadInst &LI) { | |||
4572 | if (!LI.isUnordered()) | |||
4573 | return true; | |||
4574 | const Function &F = *LI.getFunction(); | |||
4575 | // Speculative load may create a race that did not exist in the source. | |||
4576 | return F.hasFnAttribute(Attribute::SanitizeThread) || | |||
4577 | // Speculative load may load data from dirty regions. | |||
4578 | F.hasFnAttribute(Attribute::SanitizeAddress) || | |||
4579 | F.hasFnAttribute(Attribute::SanitizeHWAddress); | |||
4580 | } | |||
4581 | ||||
4582 | ||||
4583 | bool llvm::isSafeToSpeculativelyExecute(const Value *V, | |||
4584 | const Instruction *CtxI, | |||
4585 | const DominatorTree *DT, | |||
4586 | const TargetLibraryInfo *TLI) { | |||
4587 | const Operator *Inst = dyn_cast<Operator>(V); | |||
4588 | if (!Inst) | |||
4589 | return false; | |||
4590 | ||||
4591 | for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i) | |||
4592 | if (Constant *C = dyn_cast<Constant>(Inst->getOperand(i))) | |||
4593 | if (C->canTrap()) | |||
4594 | return false; | |||
4595 | ||||
4596 | switch (Inst->getOpcode()) { | |||
4597 | default: | |||
4598 | return true; | |||
4599 | case Instruction::UDiv: | |||
4600 | case Instruction::URem: { | |||
4601 | // x / y is undefined if y == 0. | |||
4602 | const APInt *V; | |||
4603 | if (match(Inst->getOperand(1), m_APInt(V))) | |||
4604 | return *V != 0; | |||
4605 | return false; | |||
4606 | } | |||
4607 | case Instruction::SDiv: | |||
4608 | case Instruction::SRem: { | |||
4609 | // x / y is undefined if y == 0 or x == INT_MIN and y == -1 | |||
4610 | const APInt *Numerator, *Denominator; | |||
4611 | if (!match(Inst->getOperand(1), m_APInt(Denominator))) | |||
4612 | return false; | |||
4613 | // We cannot hoist this division if the denominator is 0. | |||
4614 | if (*Denominator == 0) | |||
4615 | return false; | |||
4616 | // It's safe to hoist if the denominator is not 0 or -1. | |||
4617 | if (!Denominator->isAllOnesValue()) | |||
4618 | return true; | |||
4619 | // At this point we know that the denominator is -1. It is safe to hoist as | |||
4620 | // long we know that the numerator is not INT_MIN. | |||
4621 | if (match(Inst->getOperand(0), m_APInt(Numerator))) | |||
4622 | return !Numerator->isMinSignedValue(); | |||
4623 | // The numerator *might* be MinSignedValue. | |||
4624 | return false; | |||
4625 | } | |||
4626 | case Instruction::Load: { | |||
4627 | const LoadInst *LI = cast<LoadInst>(Inst); | |||
4628 | if (mustSuppressSpeculation(*LI)) | |||
4629 | return false; | |||
4630 | const DataLayout &DL = LI->getModule()->getDataLayout(); | |||
4631 | return isDereferenceableAndAlignedPointer( | |||
4632 | LI->getPointerOperand(), LI->getType(), MaybeAlign(LI->getAlignment()), | |||
4633 | DL, CtxI, DT, TLI); | |||
4634 | } | |||
4635 | case Instruction::Call: { | |||
4636 | auto *CI = cast<const CallInst>(Inst); | |||
4637 | const Function *Callee = CI->getCalledFunction(); | |||
4638 | ||||
4639 | // The called function could have undefined behavior or side-effects, even | |||
4640 | // if marked readnone nounwind. | |||
4641 | return Callee && Callee->isSpeculatable(); | |||
4642 | } | |||
4643 | case Instruction::VAArg: | |||
4644 | case Instruction::Alloca: | |||
4645 | case Instruction::Invoke: | |||
4646 | case Instruction::CallBr: | |||
4647 | case Instruction::PHI: | |||
4648 | case Instruction::Store: | |||
4649 | case Instruction::Ret: | |||
4650 | case Instruction::Br: | |||
4651 | case Instruction::IndirectBr: | |||
4652 | case Instruction::Switch: | |||
4653 | case Instruction::Unreachable: | |||
4654 | case Instruction::Fence: | |||
4655 | case Instruction::AtomicRMW: | |||
4656 | case Instruction::AtomicCmpXchg: | |||
4657 | case Instruction::LandingPad: | |||
4658 | case Instruction::Resume: | |||
4659 | case Instruction::CatchSwitch: | |||
4660 | case Instruction::CatchPad: | |||
4661 | case Instruction::CatchRet: | |||
4662 | case Instruction::CleanupPad: | |||
4663 | case Instruction::CleanupRet: | |||
4664 | return false; // Misc instructions which have effects | |||
4665 | } | |||
4666 | } | |||
4667 | ||||
4668 | bool llvm::mayBeMemoryDependent(const Instruction &I) { | |||
4669 | return I.mayReadOrWriteMemory() || !isSafeToSpeculativelyExecute(&I); | |||
4670 | } | |||
4671 | ||||
4672 | /// Convert ConstantRange OverflowResult into ValueTracking OverflowResult. | |||
4673 | static OverflowResult mapOverflowResult(ConstantRange::OverflowResult OR) { | |||
4674 | switch (OR) { | |||
4675 | case ConstantRange::OverflowResult::MayOverflow: | |||
4676 | return OverflowResult::MayOverflow; | |||
4677 | case ConstantRange::OverflowResult::AlwaysOverflowsLow: | |||
4678 | return OverflowResult::AlwaysOverflowsLow; | |||
4679 | case ConstantRange::OverflowResult::AlwaysOverflowsHigh: | |||
4680 | return OverflowResult::AlwaysOverflowsHigh; | |||
4681 | case ConstantRange::OverflowResult::NeverOverflows: | |||
4682 | return OverflowResult::NeverOverflows; | |||
4683 | } | |||
4684 | llvm_unreachable("Unknown OverflowResult")::llvm::llvm_unreachable_internal("Unknown OverflowResult", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4684); | |||
4685 | } | |||
4686 | ||||
4687 | /// Combine constant ranges from computeConstantRange() and computeKnownBits(). | |||
4688 | static ConstantRange computeConstantRangeIncludingKnownBits( | |||
4689 | const Value *V, bool ForSigned, const DataLayout &DL, unsigned Depth, | |||
4690 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
4691 | OptimizationRemarkEmitter *ORE = nullptr, bool UseInstrInfo = true) { | |||
4692 | KnownBits Known = computeKnownBits( | |||
4693 | V, DL, Depth, AC, CxtI, DT, ORE, UseInstrInfo); | |||
4694 | ConstantRange CR1 = ConstantRange::fromKnownBits(Known, ForSigned); | |||
4695 | ConstantRange CR2 = computeConstantRange(V, UseInstrInfo); | |||
4696 | ConstantRange::PreferredRangeType RangeType = | |||
4697 | ForSigned ? ConstantRange::Signed : ConstantRange::Unsigned; | |||
4698 | return CR1.intersectWith(CR2, RangeType); | |||
4699 | } | |||
4700 | ||||
4701 | OverflowResult llvm::computeOverflowForUnsignedMul( | |||
4702 | const Value *LHS, const Value *RHS, const DataLayout &DL, | |||
4703 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
4704 | bool UseInstrInfo) { | |||
4705 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4706 | nullptr, UseInstrInfo); | |||
4707 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4708 | nullptr, UseInstrInfo); | |||
4709 | ConstantRange LHSRange = ConstantRange::fromKnownBits(LHSKnown, false); | |||
4710 | ConstantRange RHSRange = ConstantRange::fromKnownBits(RHSKnown, false); | |||
4711 | return mapOverflowResult(LHSRange.unsignedMulMayOverflow(RHSRange)); | |||
4712 | } | |||
4713 | ||||
4714 | OverflowResult | |||
4715 | llvm::computeOverflowForSignedMul(const Value *LHS, const Value *RHS, | |||
4716 | const DataLayout &DL, AssumptionCache *AC, | |||
4717 | const Instruction *CxtI, | |||
4718 | const DominatorTree *DT, bool UseInstrInfo) { | |||
4719 | // Multiplying n * m significant bits yields a result of n + m significant | |||
4720 | // bits. If the total number of significant bits does not exceed the | |||
4721 | // result bit width (minus 1), there is no overflow. | |||
4722 | // This means if we have enough leading sign bits in the operands | |||
4723 | // we can guarantee that the result does not overflow. | |||
4724 | // Ref: "Hacker's Delight" by Henry Warren | |||
4725 | unsigned BitWidth = LHS->getType()->getScalarSizeInBits(); | |||
4726 | ||||
4727 | // Note that underestimating the number of sign bits gives a more | |||
4728 | // conservative answer. | |||
4729 | unsigned SignBits = ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) + | |||
4730 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT); | |||
4731 | ||||
4732 | // First handle the easy case: if we have enough sign bits there's | |||
4733 | // definitely no overflow. | |||
4734 | if (SignBits > BitWidth + 1) | |||
4735 | return OverflowResult::NeverOverflows; | |||
4736 | ||||
4737 | // There are two ambiguous cases where there can be no overflow: | |||
4738 | // SignBits == BitWidth + 1 and | |||
4739 | // SignBits == BitWidth | |||
4740 | // The second case is difficult to check, therefore we only handle the | |||
4741 | // first case. | |||
4742 | if (SignBits == BitWidth + 1) { | |||
4743 | // It overflows only when both arguments are negative and the true | |||
4744 | // product is exactly the minimum negative number. | |||
4745 | // E.g. mul i16 with 17 sign bits: 0xff00 * 0xff80 = 0x8000 | |||
4746 | // For simplicity we just check if at least one side is not negative. | |||
4747 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4748 | nullptr, UseInstrInfo); | |||
4749 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4750 | nullptr, UseInstrInfo); | |||
4751 | if (LHSKnown.isNonNegative() || RHSKnown.isNonNegative()) | |||
4752 | return OverflowResult::NeverOverflows; | |||
4753 | } | |||
4754 | return OverflowResult::MayOverflow; | |||
4755 | } | |||
4756 | ||||
4757 | OverflowResult llvm::computeOverflowForUnsignedAdd( | |||
4758 | const Value *LHS, const Value *RHS, const DataLayout &DL, | |||
4759 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
4760 | bool UseInstrInfo) { | |||
4761 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4762 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4763 | nullptr, UseInstrInfo); | |||
4764 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4765 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4766 | nullptr, UseInstrInfo); | |||
4767 | return mapOverflowResult(LHSRange.unsignedAddMayOverflow(RHSRange)); | |||
4768 | } | |||
4769 | ||||
4770 | static OverflowResult computeOverflowForSignedAdd(const Value *LHS, | |||
4771 | const Value *RHS, | |||
4772 | const AddOperator *Add, | |||
4773 | const DataLayout &DL, | |||
4774 | AssumptionCache *AC, | |||
4775 | const Instruction *CxtI, | |||
4776 | const DominatorTree *DT) { | |||
4777 | if (Add && Add->hasNoSignedWrap()) { | |||
4778 | return OverflowResult::NeverOverflows; | |||
4779 | } | |||
4780 | ||||
4781 | // If LHS and RHS each have at least two sign bits, the addition will look | |||
4782 | // like | |||
4783 | // | |||
4784 | // XX..... + | |||
4785 | // YY..... | |||
4786 | // | |||
4787 | // If the carry into the most significant position is 0, X and Y can't both | |||
4788 | // be 1 and therefore the carry out of the addition is also 0. | |||
4789 | // | |||
4790 | // If the carry into the most significant position is 1, X and Y can't both | |||
4791 | // be 0 and therefore the carry out of the addition is also 1. | |||
4792 | // | |||
4793 | // Since the carry into the most significant position is always equal to | |||
4794 | // the carry out of the addition, there is no signed overflow. | |||
4795 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && | |||
4796 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) | |||
4797 | return OverflowResult::NeverOverflows; | |||
4798 | ||||
4799 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4800 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4801 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4802 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4803 | OverflowResult OR = | |||
4804 | mapOverflowResult(LHSRange.signedAddMayOverflow(RHSRange)); | |||
4805 | if (OR != OverflowResult::MayOverflow) | |||
4806 | return OR; | |||
4807 | ||||
4808 | // The remaining code needs Add to be available. Early returns if not so. | |||
4809 | if (!Add) | |||
4810 | return OverflowResult::MayOverflow; | |||
4811 | ||||
4812 | // If the sign of Add is the same as at least one of the operands, this add | |||
4813 | // CANNOT overflow. If this can be determined from the known bits of the | |||
4814 | // operands the above signedAddMayOverflow() check will have already done so. | |||
4815 | // The only other way to improve on the known bits is from an assumption, so | |||
4816 | // call computeKnownBitsFromAssume() directly. | |||
4817 | bool LHSOrRHSKnownNonNegative = | |||
4818 | (LHSRange.isAllNonNegative() || RHSRange.isAllNonNegative()); | |||
4819 | bool LHSOrRHSKnownNegative = | |||
4820 | (LHSRange.isAllNegative() || RHSRange.isAllNegative()); | |||
4821 | if (LHSOrRHSKnownNonNegative || LHSOrRHSKnownNegative) { | |||
4822 | KnownBits AddKnown(LHSRange.getBitWidth()); | |||
4823 | computeKnownBitsFromAssume( | |||
4824 | Add, AddKnown, /*Depth=*/0, Query(DL, AC, CxtI, DT, true)); | |||
4825 | if ((AddKnown.isNonNegative() && LHSOrRHSKnownNonNegative) || | |||
4826 | (AddKnown.isNegative() && LHSOrRHSKnownNegative)) | |||
4827 | return OverflowResult::NeverOverflows; | |||
4828 | } | |||
4829 | ||||
4830 | return OverflowResult::MayOverflow; | |||
4831 | } | |||
4832 | ||||
4833 | OverflowResult llvm::computeOverflowForUnsignedSub(const Value *LHS, | |||
4834 | const Value *RHS, | |||
4835 | const DataLayout &DL, | |||
4836 | AssumptionCache *AC, | |||
4837 | const Instruction *CxtI, | |||
4838 | const DominatorTree *DT) { | |||
4839 | // Checking for conditions implied by dominating conditions may be expensive. | |||
4840 | // Limit it to usub_with_overflow calls for now. | |||
4841 | if (match(CxtI, | |||
4842 | m_Intrinsic<Intrinsic::usub_with_overflow>(m_Value(), m_Value()))) | |||
4843 | if (auto C = | |||
4844 | isImpliedByDomCondition(CmpInst::ICMP_UGE, LHS, RHS, CxtI, DL)) { | |||
4845 | if (*C) | |||
4846 | return OverflowResult::NeverOverflows; | |||
4847 | return OverflowResult::AlwaysOverflowsLow; | |||
4848 | } | |||
4849 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4850 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4851 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4852 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4853 | return mapOverflowResult(LHSRange.unsignedSubMayOverflow(RHSRange)); | |||
4854 | } | |||
4855 | ||||
4856 | OverflowResult llvm::computeOverflowForSignedSub(const Value *LHS, | |||
4857 | const Value *RHS, | |||
4858 | const DataLayout &DL, | |||
4859 | AssumptionCache *AC, | |||
4860 | const Instruction *CxtI, | |||
4861 | const DominatorTree *DT) { | |||
4862 | // If LHS and RHS each have at least two sign bits, the subtraction | |||
4863 | // cannot overflow. | |||
4864 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && | |||
4865 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) | |||
4866 | return OverflowResult::NeverOverflows; | |||
4867 | ||||
4868 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4869 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4870 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4871 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4872 | return mapOverflowResult(LHSRange.signedSubMayOverflow(RHSRange)); | |||
4873 | } | |||
4874 | ||||
4875 | bool llvm::isOverflowIntrinsicNoWrap(const WithOverflowInst *WO, | |||
4876 | const DominatorTree &DT) { | |||
4877 | SmallVector<const BranchInst *, 2> GuardingBranches; | |||
4878 | SmallVector<const ExtractValueInst *, 2> Results; | |||
4879 | ||||
4880 | for (const User *U : WO->users()) { | |||
4881 | if (const auto *EVI = dyn_cast<ExtractValueInst>(U)) { | |||
4882 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4882, __extension__ __PRETTY_FUNCTION__)); | |||
4883 | ||||
4884 | if (EVI->getIndices()[0] == 0) | |||
4885 | Results.push_back(EVI); | |||
4886 | else { | |||
4887 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4887, __extension__ __PRETTY_FUNCTION__)); | |||
4888 | ||||
4889 | for (const auto *U : EVI->users()) | |||
4890 | if (const auto *B = dyn_cast<BranchInst>(U)) { | |||
4891 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 4891, __extension__ __PRETTY_FUNCTION__)); | |||
4892 | GuardingBranches.push_back(B); | |||
4893 | } | |||
4894 | } | |||
4895 | } else { | |||
4896 | // We are using the aggregate directly in a way we don't want to analyze | |||
4897 | // here (storing it to a global, say). | |||
4898 | return false; | |||
4899 | } | |||
4900 | } | |||
4901 | ||||
4902 | auto AllUsesGuardedByBranch = [&](const BranchInst *BI) { | |||
4903 | BasicBlockEdge NoWrapEdge(BI->getParent(), BI->getSuccessor(1)); | |||
4904 | if (!NoWrapEdge.isSingleEdge()) | |||
4905 | return false; | |||
4906 | ||||
4907 | // Check if all users of the add are provably no-wrap. | |||
4908 | for (const auto *Result : Results) { | |||
4909 | // If the extractvalue itself is not executed on overflow, the we don't | |||
4910 | // need to check each use separately, since domination is transitive. | |||
4911 | if (DT.dominates(NoWrapEdge, Result->getParent())) | |||
4912 | continue; | |||
4913 | ||||
4914 | for (auto &RU : Result->uses()) | |||
4915 | if (!DT.dominates(NoWrapEdge, RU)) | |||
4916 | return false; | |||
4917 | } | |||
4918 | ||||
4919 | return true; | |||
4920 | }; | |||
4921 | ||||
4922 | return llvm::any_of(GuardingBranches, AllUsesGuardedByBranch); | |||
4923 | } | |||
4924 | ||||
4925 | static bool canCreateUndefOrPoison(const Operator *Op, bool PoisonOnly) { | |||
4926 | // See whether I has flags that may create poison | |||
4927 | if (const auto *OvOp = dyn_cast<OverflowingBinaryOperator>(Op)) { | |||
4928 | if (OvOp->hasNoSignedWrap() || OvOp->hasNoUnsignedWrap()) | |||
4929 | return true; | |||
4930 | } | |||
4931 | if (const auto *ExactOp = dyn_cast<PossiblyExactOperator>(Op)) | |||
4932 | if (ExactOp->isExact()) | |||
4933 | return true; | |||
4934 | if (const auto *FP = dyn_cast<FPMathOperator>(Op)) { | |||
4935 | auto FMF = FP->getFastMathFlags(); | |||
4936 | if (FMF.noNaNs() || FMF.noInfs()) | |||
4937 | return true; | |||
4938 | } | |||
4939 | ||||
4940 | unsigned Opcode = Op->getOpcode(); | |||
4941 | ||||
4942 | // Check whether opcode is a poison/undef-generating operation | |||
4943 | switch (Opcode) { | |||
4944 | case Instruction::Shl: | |||
4945 | case Instruction::AShr: | |||
4946 | case Instruction::LShr: { | |||
4947 | // Shifts return poison if shiftwidth is larger than the bitwidth. | |||
4948 | if (auto *C = dyn_cast<Constant>(Op->getOperand(1))) { | |||
4949 | SmallVector<Constant *, 4> ShiftAmounts; | |||
4950 | if (auto *FVTy = dyn_cast<FixedVectorType>(C->getType())) { | |||
4951 | unsigned NumElts = FVTy->getNumElements(); | |||
4952 | for (unsigned i = 0; i < NumElts; ++i) | |||
4953 | ShiftAmounts.push_back(C->getAggregateElement(i)); | |||
4954 | } else if (isa<ScalableVectorType>(C->getType())) | |||
4955 | return true; // Can't tell, just return true to be safe | |||
4956 | else | |||
4957 | ShiftAmounts.push_back(C); | |||
4958 | ||||
4959 | bool Safe = llvm::all_of(ShiftAmounts, [](Constant *C) { | |||
4960 | auto *CI = dyn_cast_or_null<ConstantInt>(C); | |||
4961 | return CI && CI->getValue().ult(C->getType()->getIntegerBitWidth()); | |||
4962 | }); | |||
4963 | return !Safe; | |||
4964 | } | |||
4965 | return true; | |||
4966 | } | |||
4967 | case Instruction::FPToSI: | |||
4968 | case Instruction::FPToUI: | |||
4969 | // fptosi/ui yields poison if the resulting value does not fit in the | |||
4970 | // destination type. | |||
4971 | return true; | |||
4972 | case Instruction::Call: | |||
4973 | if (auto *II = dyn_cast<IntrinsicInst>(Op)) { | |||
4974 | switch (II->getIntrinsicID()) { | |||
4975 | // TODO: Add more intrinsics. | |||
4976 | case Intrinsic::ctpop: | |||
4977 | case Intrinsic::sadd_with_overflow: | |||
4978 | case Intrinsic::ssub_with_overflow: | |||
4979 | case Intrinsic::smul_with_overflow: | |||
4980 | case Intrinsic::uadd_with_overflow: | |||
4981 | case Intrinsic::usub_with_overflow: | |||
4982 | case Intrinsic::umul_with_overflow: | |||
4983 | return false; | |||
4984 | } | |||
4985 | } | |||
4986 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
4987 | case Instruction::CallBr: | |||
4988 | case Instruction::Invoke: { | |||
4989 | const auto *CB = cast<CallBase>(Op); | |||
4990 | return !CB->hasRetAttr(Attribute::NoUndef); | |||
4991 | } | |||
4992 | case Instruction::InsertElement: | |||
4993 | case Instruction::ExtractElement: { | |||
4994 | // If index exceeds the length of the vector, it returns poison | |||
4995 | auto *VTy = cast<VectorType>(Op->getOperand(0)->getType()); | |||
4996 | unsigned IdxOp = Op->getOpcode() == Instruction::InsertElement ? 2 : 1; | |||
4997 | auto *Idx = dyn_cast<ConstantInt>(Op->getOperand(IdxOp)); | |||
4998 | if (!Idx || Idx->getValue().uge(VTy->getElementCount().getKnownMinValue())) | |||
4999 | return true; | |||
5000 | return false; | |||
5001 | } | |||
5002 | case Instruction::ShuffleVector: { | |||
5003 | // shufflevector may return undef. | |||
5004 | if (PoisonOnly) | |||
5005 | return false; | |||
5006 | ArrayRef<int> Mask = isa<ConstantExpr>(Op) | |||
5007 | ? cast<ConstantExpr>(Op)->getShuffleMask() | |||
5008 | : cast<ShuffleVectorInst>(Op)->getShuffleMask(); | |||
5009 | return is_contained(Mask, UndefMaskElem); | |||
5010 | } | |||
5011 | case Instruction::FNeg: | |||
5012 | case Instruction::PHI: | |||
5013 | case Instruction::Select: | |||
5014 | case Instruction::URem: | |||
5015 | case Instruction::SRem: | |||
5016 | case Instruction::ExtractValue: | |||
5017 | case Instruction::InsertValue: | |||
5018 | case Instruction::Freeze: | |||
5019 | case Instruction::ICmp: | |||
5020 | case Instruction::FCmp: | |||
5021 | return false; | |||
5022 | case Instruction::GetElementPtr: { | |||
5023 | const auto *GEP = cast<GEPOperator>(Op); | |||
5024 | return GEP->isInBounds(); | |||
5025 | } | |||
5026 | default: { | |||
5027 | const auto *CE = dyn_cast<ConstantExpr>(Op); | |||
5028 | if (isa<CastInst>(Op) || (CE && CE->isCast())) | |||
5029 | return false; | |||
5030 | else if (Instruction::isBinaryOp(Opcode)) | |||
5031 | return false; | |||
5032 | // Be conservative and return true. | |||
5033 | return true; | |||
5034 | } | |||
5035 | } | |||
5036 | } | |||
5037 | ||||
5038 | bool llvm::canCreateUndefOrPoison(const Operator *Op) { | |||
5039 | return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/false); | |||
5040 | } | |||
5041 | ||||
5042 | bool llvm::canCreatePoison(const Operator *Op) { | |||
5043 | return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/true); | |||
5044 | } | |||
5045 | ||||
5046 | static bool directlyImpliesPoison(const Value *ValAssumedPoison, | |||
5047 | const Value *V, unsigned Depth) { | |||
5048 | if (ValAssumedPoison == V) | |||
5049 | return true; | |||
5050 | ||||
5051 | const unsigned MaxDepth = 2; | |||
5052 | if (Depth >= MaxDepth) | |||
5053 | return false; | |||
5054 | ||||
5055 | if (const auto *I = dyn_cast<Instruction>(V)) { | |||
5056 | if (propagatesPoison(cast<Operator>(I))) | |||
5057 | return any_of(I->operands(), [=](const Value *Op) { | |||
5058 | return directlyImpliesPoison(ValAssumedPoison, Op, Depth + 1); | |||
5059 | }); | |||
5060 | ||||
5061 | // 'select ValAssumedPoison, _, _' is poison. | |||
5062 | if (const auto *SI = dyn_cast<SelectInst>(I)) | |||
5063 | return directlyImpliesPoison(ValAssumedPoison, SI->getCondition(), | |||
5064 | Depth + 1); | |||
5065 | // V = extractvalue V0, idx | |||
5066 | // V2 = extractvalue V0, idx2 | |||
5067 | // V0's elements are all poison or not. (e.g., add_with_overflow) | |||
5068 | const WithOverflowInst *II; | |||
5069 | if (match(I, m_ExtractValue(m_WithOverflowInst(II))) && | |||
5070 | (match(ValAssumedPoison, m_ExtractValue(m_Specific(II))) || | |||
5071 | llvm::is_contained(II->arg_operands(), ValAssumedPoison))) | |||
5072 | return true; | |||
5073 | } | |||
5074 | return false; | |||
5075 | } | |||
5076 | ||||
5077 | static bool impliesPoison(const Value *ValAssumedPoison, const Value *V, | |||
5078 | unsigned Depth) { | |||
5079 | if (isGuaranteedNotToBeUndefOrPoison(ValAssumedPoison)) | |||
5080 | return true; | |||
5081 | ||||
5082 | if (directlyImpliesPoison(ValAssumedPoison, V, /* Depth */ 0)) | |||
5083 | return true; | |||
5084 | ||||
5085 | const unsigned MaxDepth = 2; | |||
5086 | if (Depth >= MaxDepth) | |||
5087 | return false; | |||
5088 | ||||
5089 | const auto *I = dyn_cast<Instruction>(ValAssumedPoison); | |||
5090 | if (I && !canCreatePoison(cast<Operator>(I))) { | |||
5091 | return all_of(I->operands(), [=](const Value *Op) { | |||
5092 | return impliesPoison(Op, V, Depth + 1); | |||
5093 | }); | |||
5094 | } | |||
5095 | return false; | |||
5096 | } | |||
5097 | ||||
5098 | bool llvm::impliesPoison(const Value *ValAssumedPoison, const Value *V) { | |||
5099 | return ::impliesPoison(ValAssumedPoison, V, /* Depth */ 0); | |||
5100 | } | |||
5101 | ||||
5102 | static bool programUndefinedIfUndefOrPoison(const Value *V, | |||
5103 | bool PoisonOnly); | |||
5104 | ||||
5105 | static bool isGuaranteedNotToBeUndefOrPoison(const Value *V, | |||
5106 | AssumptionCache *AC, | |||
5107 | const Instruction *CtxI, | |||
5108 | const DominatorTree *DT, | |||
5109 | unsigned Depth, bool PoisonOnly) { | |||
5110 | if (Depth >= MaxAnalysisRecursionDepth) | |||
5111 | return false; | |||
5112 | ||||
5113 | if (isa<MetadataAsValue>(V)) | |||
5114 | return false; | |||
5115 | ||||
5116 | if (const auto *A = dyn_cast<Argument>(V)) { | |||
5117 | if (A->hasAttribute(Attribute::NoUndef)) | |||
5118 | return true; | |||
5119 | } | |||
5120 | ||||
5121 | if (auto *C = dyn_cast<Constant>(V)) { | |||
5122 | if (isa<UndefValue>(C)) | |||
5123 | return PoisonOnly && !isa<PoisonValue>(C); | |||
5124 | ||||
5125 | if (isa<ConstantInt>(C) || isa<GlobalVariable>(C) || isa<ConstantFP>(V) || | |||
5126 | isa<ConstantPointerNull>(C) || isa<Function>(C)) | |||
5127 | return true; | |||
5128 | ||||
5129 | if (C->getType()->isVectorTy() && !isa<ConstantExpr>(C)) | |||
5130 | return (PoisonOnly ? !C->containsPoisonElement() | |||
5131 | : !C->containsUndefOrPoisonElement()) && | |||
5132 | !C->containsConstantExpression(); | |||
5133 | } | |||
5134 | ||||
5135 | // Strip cast operations from a pointer value. | |||
5136 | // Note that stripPointerCastsSameRepresentation can strip off getelementptr | |||
5137 | // inbounds with zero offset. To guarantee that the result isn't poison, the | |||
5138 | // stripped pointer is checked as it has to be pointing into an allocated | |||
5139 | // object or be null `null` to ensure `inbounds` getelement pointers with a | |||
5140 | // zero offset could not produce poison. | |||
5141 | // It can strip off addrspacecast that do not change bit representation as | |||
5142 | // well. We believe that such addrspacecast is equivalent to no-op. | |||
5143 | auto *StrippedV = V->stripPointerCastsSameRepresentation(); | |||
5144 | if (isa<AllocaInst>(StrippedV) || isa<GlobalVariable>(StrippedV) || | |||
5145 | isa<Function>(StrippedV) || isa<ConstantPointerNull>(StrippedV)) | |||
5146 | return true; | |||
5147 | ||||
5148 | auto OpCheck = [&](const Value *V) { | |||
5149 | return isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth + 1, | |||
5150 | PoisonOnly); | |||
5151 | }; | |||
5152 | ||||
5153 | if (auto *Opr = dyn_cast<Operator>(V)) { | |||
5154 | // If the value is a freeze instruction, then it can never | |||
5155 | // be undef or poison. | |||
5156 | if (isa<FreezeInst>(V)) | |||
5157 | return true; | |||
5158 | ||||
5159 | if (const auto *CB = dyn_cast<CallBase>(V)) { | |||
5160 | if (CB->hasRetAttr(Attribute::NoUndef)) | |||
5161 | return true; | |||
5162 | } | |||
5163 | ||||
5164 | if (const auto *PN = dyn_cast<PHINode>(V)) { | |||
5165 | unsigned Num = PN->getNumIncomingValues(); | |||
5166 | bool IsWellDefined = true; | |||
5167 | for (unsigned i = 0; i < Num; ++i) { | |||
5168 | auto *TI = PN->getIncomingBlock(i)->getTerminator(); | |||
5169 | if (!isGuaranteedNotToBeUndefOrPoison(PN->getIncomingValue(i), AC, TI, | |||
5170 | DT, Depth + 1, PoisonOnly)) { | |||
5171 | IsWellDefined = false; | |||
5172 | break; | |||
5173 | } | |||
5174 | } | |||
5175 | if (IsWellDefined) | |||
5176 | return true; | |||
5177 | } else if (!canCreateUndefOrPoison(Opr) && all_of(Opr->operands(), OpCheck)) | |||
5178 | return true; | |||
5179 | } | |||
5180 | ||||
5181 | if (auto *I = dyn_cast<LoadInst>(V)) | |||
5182 | if (I->getMetadata(LLVMContext::MD_noundef)) | |||
5183 | return true; | |||
5184 | ||||
5185 | if (programUndefinedIfUndefOrPoison(V, PoisonOnly)) | |||
5186 | return true; | |||
5187 | ||||
5188 | // CxtI may be null or a cloned instruction. | |||
5189 | if (!CtxI || !CtxI->getParent() || !DT) | |||
5190 | return false; | |||
5191 | ||||
5192 | auto *DNode = DT->getNode(CtxI->getParent()); | |||
5193 | if (!DNode) | |||
5194 | // Unreachable block | |||
5195 | return false; | |||
5196 | ||||
5197 | // If V is used as a branch condition before reaching CtxI, V cannot be | |||
5198 | // undef or poison. | |||
5199 | // br V, BB1, BB2 | |||
5200 | // BB1: | |||
5201 | // CtxI ; V cannot be undef or poison here | |||
5202 | auto *Dominator = DNode->getIDom(); | |||
5203 | while (Dominator) { | |||
5204 | auto *TI = Dominator->getBlock()->getTerminator(); | |||
5205 | ||||
5206 | Value *Cond = nullptr; | |||
5207 | if (auto BI = dyn_cast<BranchInst>(TI)) { | |||
5208 | if (BI->isConditional()) | |||
5209 | Cond = BI->getCondition(); | |||
5210 | } else if (auto SI = dyn_cast<SwitchInst>(TI)) { | |||
5211 | Cond = SI->getCondition(); | |||
5212 | } | |||
5213 | ||||
5214 | if (Cond) { | |||
5215 | if (Cond == V) | |||
5216 | return true; | |||
5217 | else if (PoisonOnly && isa<Operator>(Cond)) { | |||
5218 | // For poison, we can analyze further | |||
5219 | auto *Opr = cast<Operator>(Cond); | |||
5220 | if (propagatesPoison(Opr) && is_contained(Opr->operand_values(), V)) | |||
5221 | return true; | |||
5222 | } | |||
5223 | } | |||
5224 | ||||
5225 | Dominator = Dominator->getIDom(); | |||
5226 | } | |||
5227 | ||||
5228 | SmallVector<Attribute::AttrKind, 2> AttrKinds{Attribute::NoUndef}; | |||
5229 | if (getKnowledgeValidInContext(V, AttrKinds, CtxI, DT, AC)) | |||
5230 | return true; | |||
5231 | ||||
5232 | return false; | |||
5233 | } | |||
5234 | ||||
5235 | bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V, AssumptionCache *AC, | |||
5236 | const Instruction *CtxI, | |||
5237 | const DominatorTree *DT, | |||
5238 | unsigned Depth) { | |||
5239 | return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, false); | |||
5240 | } | |||
5241 | ||||
5242 | bool llvm::isGuaranteedNotToBePoison(const Value *V, AssumptionCache *AC, | |||
5243 | const Instruction *CtxI, | |||
5244 | const DominatorTree *DT, unsigned Depth) { | |||
5245 | return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, true); | |||
5246 | } | |||
5247 | ||||
5248 | OverflowResult llvm::computeOverflowForSignedAdd(const AddOperator *Add, | |||
5249 | const DataLayout &DL, | |||
5250 | AssumptionCache *AC, | |||
5251 | const Instruction *CxtI, | |||
5252 | const DominatorTree *DT) { | |||
5253 | return ::computeOverflowForSignedAdd(Add->getOperand(0), Add->getOperand(1), | |||
5254 | Add, DL, AC, CxtI, DT); | |||
5255 | } | |||
5256 | ||||
5257 | OverflowResult llvm::computeOverflowForSignedAdd(const Value *LHS, | |||
5258 | const Value *RHS, | |||
5259 | const DataLayout &DL, | |||
5260 | AssumptionCache *AC, | |||
5261 | const Instruction *CxtI, | |||
5262 | const DominatorTree *DT) { | |||
5263 | return ::computeOverflowForSignedAdd(LHS, RHS, nullptr, DL, AC, CxtI, DT); | |||
5264 | } | |||
5265 | ||||
5266 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const Instruction *I) { | |||
5267 | // Note: An atomic operation isn't guaranteed to return in a reasonable amount | |||
5268 | // of time because it's possible for another thread to interfere with it for an | |||
5269 | // arbitrary length of time, but programs aren't allowed to rely on that. | |||
5270 | ||||
5271 | // If there is no successor, then execution can't transfer to it. | |||
5272 | if (isa<ReturnInst>(I)) | |||
5273 | return false; | |||
5274 | if (isa<UnreachableInst>(I)) | |||
5275 | return false; | |||
5276 | ||||
5277 | // Note: Do not add new checks here; instead, change Instruction::mayThrow or | |||
5278 | // Instruction::willReturn. | |||
5279 | // | |||
5280 | // FIXME: Move this check into Instruction::willReturn. | |||
5281 | if (isa<CatchPadInst>(I)) { | |||
5282 | switch (classifyEHPersonality(I->getFunction()->getPersonalityFn())) { | |||
5283 | default: | |||
5284 | // A catchpad may invoke exception object constructors and such, which | |||
5285 | // in some languages can be arbitrary code, so be conservative by default. | |||
5286 | return false; | |||
5287 | case EHPersonality::CoreCLR: | |||
5288 | // For CoreCLR, it just involves a type test. | |||
5289 | return true; | |||
5290 | } | |||
5291 | } | |||
5292 | ||||
5293 | // An instruction that returns without throwing must transfer control flow | |||
5294 | // to a successor. | |||
5295 | return !I->mayThrow() && I->willReturn(); | |||
5296 | } | |||
5297 | ||||
5298 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB) { | |||
5299 | // TODO: This is slightly conservative for invoke instruction since exiting | |||
5300 | // via an exception *is* normal control for them. | |||
5301 | for (const Instruction &I : *BB) | |||
5302 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
5303 | return false; | |||
5304 | return true; | |||
5305 | } | |||
5306 | ||||
5307 | bool llvm::isGuaranteedToExecuteForEveryIteration(const Instruction *I, | |||
5308 | const Loop *L) { | |||
5309 | // The loop header is guaranteed to be executed for every iteration. | |||
5310 | // | |||
5311 | // FIXME: Relax this constraint to cover all basic blocks that are | |||
5312 | // guaranteed to be executed at every iteration. | |||
5313 | if (I->getParent() != L->getHeader()) return false; | |||
5314 | ||||
5315 | for (const Instruction &LI : *L->getHeader()) { | |||
5316 | if (&LI == I) return true; | |||
5317 | if (!isGuaranteedToTransferExecutionToSuccessor(&LI)) return false; | |||
5318 | } | |||
5319 | llvm_unreachable("Instruction not contained in its own parent basic block.")::llvm::llvm_unreachable_internal("Instruction not contained in its own parent basic block." , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 5319); | |||
5320 | } | |||
5321 | ||||
5322 | bool llvm::propagatesPoison(const Operator *I) { | |||
5323 | switch (I->getOpcode()) { | |||
5324 | case Instruction::Freeze: | |||
5325 | case Instruction::Select: | |||
5326 | case Instruction::PHI: | |||
5327 | case Instruction::Invoke: | |||
5328 | return false; | |||
5329 | case Instruction::Call: | |||
5330 | if (auto *II = dyn_cast<IntrinsicInst>(I)) { | |||
5331 | switch (II->getIntrinsicID()) { | |||
5332 | // TODO: Add more intrinsics. | |||
5333 | case Intrinsic::sadd_with_overflow: | |||
5334 | case Intrinsic::ssub_with_overflow: | |||
5335 | case Intrinsic::smul_with_overflow: | |||
5336 | case Intrinsic::uadd_with_overflow: | |||
5337 | case Intrinsic::usub_with_overflow: | |||
5338 | case Intrinsic::umul_with_overflow: | |||
5339 | // If an input is a vector containing a poison element, the | |||
5340 | // two output vectors (calculated results, overflow bits)' | |||
5341 | // corresponding lanes are poison. | |||
5342 | return true; | |||
5343 | case Intrinsic::ctpop: | |||
5344 | return true; | |||
5345 | } | |||
5346 | } | |||
5347 | return false; | |||
5348 | case Instruction::ICmp: | |||
5349 | case Instruction::FCmp: | |||
5350 | case Instruction::GetElementPtr: | |||
5351 | return true; | |||
5352 | default: | |||
5353 | if (isa<BinaryOperator>(I) || isa<UnaryOperator>(I) || isa<CastInst>(I)) | |||
5354 | return true; | |||
5355 | ||||
5356 | // Be conservative and return false. | |||
5357 | return false; | |||
5358 | } | |||
5359 | } | |||
5360 | ||||
5361 | void llvm::getGuaranteedWellDefinedOps( | |||
5362 | const Instruction *I, SmallPtrSetImpl<const Value *> &Operands) { | |||
5363 | switch (I->getOpcode()) { | |||
5364 | case Instruction::Store: | |||
5365 | Operands.insert(cast<StoreInst>(I)->getPointerOperand()); | |||
5366 | break; | |||
5367 | ||||
5368 | case Instruction::Load: | |||
5369 | Operands.insert(cast<LoadInst>(I)->getPointerOperand()); | |||
5370 | break; | |||
5371 | ||||
5372 | // Since dereferenceable attribute imply noundef, atomic operations | |||
5373 | // also implicitly have noundef pointers too | |||
5374 | case Instruction::AtomicCmpXchg: | |||
5375 | Operands.insert(cast<AtomicCmpXchgInst>(I)->getPointerOperand()); | |||
5376 | break; | |||
5377 | ||||
5378 | case Instruction::AtomicRMW: | |||
5379 | Operands.insert(cast<AtomicRMWInst>(I)->getPointerOperand()); | |||
5380 | break; | |||
5381 | ||||
5382 | case Instruction::Call: | |||
5383 | case Instruction::Invoke: { | |||
5384 | const CallBase *CB = cast<CallBase>(I); | |||
5385 | if (CB->isIndirectCall()) | |||
5386 | Operands.insert(CB->getCalledOperand()); | |||
5387 | for (unsigned i = 0; i < CB->arg_size(); ++i) { | |||
5388 | if (CB->paramHasAttr(i, Attribute::NoUndef) || | |||
5389 | CB->paramHasAttr(i, Attribute::Dereferenceable)) | |||
5390 | Operands.insert(CB->getArgOperand(i)); | |||
5391 | } | |||
5392 | break; | |||
5393 | } | |||
5394 | ||||
5395 | default: | |||
5396 | break; | |||
5397 | } | |||
5398 | } | |||
5399 | ||||
5400 | void llvm::getGuaranteedNonPoisonOps(const Instruction *I, | |||
5401 | SmallPtrSetImpl<const Value *> &Operands) { | |||
5402 | getGuaranteedWellDefinedOps(I, Operands); | |||
5403 | switch (I->getOpcode()) { | |||
5404 | // Divisors of these operations are allowed to be partially undef. | |||
5405 | case Instruction::UDiv: | |||
5406 | case Instruction::SDiv: | |||
5407 | case Instruction::URem: | |||
5408 | case Instruction::SRem: | |||
5409 | Operands.insert(I->getOperand(1)); | |||
5410 | break; | |||
5411 | ||||
5412 | default: | |||
5413 | break; | |||
5414 | } | |||
5415 | } | |||
5416 | ||||
5417 | bool llvm::mustTriggerUB(const Instruction *I, | |||
5418 | const SmallSet<const Value *, 16>& KnownPoison) { | |||
5419 | SmallPtrSet<const Value *, 4> NonPoisonOps; | |||
5420 | getGuaranteedNonPoisonOps(I, NonPoisonOps); | |||
5421 | ||||
5422 | for (const auto *V : NonPoisonOps) | |||
5423 | if (KnownPoison.count(V)) | |||
5424 | return true; | |||
5425 | ||||
5426 | return false; | |||
5427 | } | |||
5428 | ||||
5429 | static bool programUndefinedIfUndefOrPoison(const Value *V, | |||
5430 | bool PoisonOnly) { | |||
5431 | // We currently only look for uses of values within the same basic | |||
5432 | // block, as that makes it easier to guarantee that the uses will be | |||
5433 | // executed given that Inst is executed. | |||
5434 | // | |||
5435 | // FIXME: Expand this to consider uses beyond the same basic block. To do | |||
5436 | // this, look out for the distinction between post-dominance and strong | |||
5437 | // post-dominance. | |||
5438 | const BasicBlock *BB = nullptr; | |||
5439 | BasicBlock::const_iterator Begin; | |||
5440 | if (const auto *Inst = dyn_cast<Instruction>(V)) { | |||
5441 | BB = Inst->getParent(); | |||
5442 | Begin = Inst->getIterator(); | |||
5443 | Begin++; | |||
5444 | } else if (const auto *Arg = dyn_cast<Argument>(V)) { | |||
5445 | BB = &Arg->getParent()->getEntryBlock(); | |||
5446 | Begin = BB->begin(); | |||
5447 | } else { | |||
5448 | return false; | |||
5449 | } | |||
5450 | ||||
5451 | // Limit number of instructions we look at, to avoid scanning through large | |||
5452 | // blocks. The current limit is chosen arbitrarily. | |||
5453 | unsigned ScanLimit = 32; | |||
5454 | BasicBlock::const_iterator End = BB->end(); | |||
5455 | ||||
5456 | if (!PoisonOnly) { | |||
5457 | // Since undef does not propagate eagerly, be conservative & just check | |||
5458 | // whether a value is directly passed to an instruction that must take | |||
5459 | // well-defined operands. | |||
5460 | ||||
5461 | for (auto &I : make_range(Begin, End)) { | |||
5462 | if (isa<DbgInfoIntrinsic>(I)) | |||
5463 | continue; | |||
5464 | if (--ScanLimit == 0) | |||
5465 | break; | |||
5466 | ||||
5467 | SmallPtrSet<const Value *, 4> WellDefinedOps; | |||
5468 | getGuaranteedWellDefinedOps(&I, WellDefinedOps); | |||
5469 | if (WellDefinedOps.contains(V)) | |||
5470 | return true; | |||
5471 | ||||
5472 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
5473 | break; | |||
5474 | } | |||
5475 | return false; | |||
5476 | } | |||
5477 | ||||
5478 | // Set of instructions that we have proved will yield poison if Inst | |||
5479 | // does. | |||
5480 | SmallSet<const Value *, 16> YieldsPoison; | |||
5481 | SmallSet<const BasicBlock *, 4> Visited; | |||
5482 | ||||
5483 | YieldsPoison.insert(V); | |||
5484 | auto Propagate = [&](const User *User) { | |||
5485 | if (propagatesPoison(cast<Operator>(User))) | |||
5486 | YieldsPoison.insert(User); | |||
5487 | }; | |||
5488 | for_each(V->users(), Propagate); | |||
5489 | Visited.insert(BB); | |||
5490 | ||||
5491 | while (true) { | |||
5492 | for (auto &I : make_range(Begin, End)) { | |||
5493 | if (isa<DbgInfoIntrinsic>(I)) | |||
5494 | continue; | |||
5495 | if (--ScanLimit == 0) | |||
5496 | return false; | |||
5497 | if (mustTriggerUB(&I, YieldsPoison)) | |||
5498 | return true; | |||
5499 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
5500 | return false; | |||
5501 | ||||
5502 | // Mark poison that propagates from I through uses of I. | |||
5503 | if (YieldsPoison.count(&I)) | |||
5504 | for_each(I.users(), Propagate); | |||
5505 | } | |||
5506 | ||||
5507 | BB = BB->getSingleSuccessor(); | |||
5508 | if (!BB || !Visited.insert(BB).second) | |||
5509 | break; | |||
5510 | ||||
5511 | Begin = BB->getFirstNonPHI()->getIterator(); | |||
5512 | End = BB->end(); | |||
5513 | } | |||
5514 | return false; | |||
5515 | } | |||
5516 | ||||
5517 | bool llvm::programUndefinedIfUndefOrPoison(const Instruction *Inst) { | |||
5518 | return ::programUndefinedIfUndefOrPoison(Inst, false); | |||
5519 | } | |||
5520 | ||||
5521 | bool llvm::programUndefinedIfPoison(const Instruction *Inst) { | |||
5522 | return ::programUndefinedIfUndefOrPoison(Inst, true); | |||
5523 | } | |||
5524 | ||||
5525 | static bool isKnownNonNaN(const Value *V, FastMathFlags FMF) { | |||
5526 | if (FMF.noNaNs()) | |||
5527 | return true; | |||
5528 | ||||
5529 | if (auto *C = dyn_cast<ConstantFP>(V)) | |||
5530 | return !C->isNaN(); | |||
5531 | ||||
5532 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { | |||
5533 | if (!C->getElementType()->isFloatingPointTy()) | |||
5534 | return false; | |||
5535 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { | |||
5536 | if (C->getElementAsAPFloat(I).isNaN()) | |||
5537 | return false; | |||
5538 | } | |||
5539 | return true; | |||
5540 | } | |||
5541 | ||||
5542 | if (isa<ConstantAggregateZero>(V)) | |||
5543 | return true; | |||
5544 | ||||
5545 | return false; | |||
5546 | } | |||
5547 | ||||
5548 | static bool isKnownNonZero(const Value *V) { | |||
5549 | if (auto *C = dyn_cast<ConstantFP>(V)) | |||
5550 | return !C->isZero(); | |||
5551 | ||||
5552 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { | |||
5553 | if (!C->getElementType()->isFloatingPointTy()) | |||
5554 | return false; | |||
5555 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { | |||
5556 | if (C->getElementAsAPFloat(I).isZero()) | |||
5557 | return false; | |||
5558 | } | |||
5559 | return true; | |||
5560 | } | |||
5561 | ||||
5562 | return false; | |||
5563 | } | |||
5564 | ||||
5565 | /// Match clamp pattern for float types without care about NaNs or signed zeros. | |||
5566 | /// Given non-min/max outer cmp/select from the clamp pattern this | |||
5567 | /// function recognizes if it can be substitued by a "canonical" min/max | |||
5568 | /// pattern. | |||
5569 | static SelectPatternResult matchFastFloatClamp(CmpInst::Predicate Pred, | |||
5570 | Value *CmpLHS, Value *CmpRHS, | |||
5571 | Value *TrueVal, Value *FalseVal, | |||
5572 | Value *&LHS, Value *&RHS) { | |||
5573 | // Try to match | |||
5574 | // X < C1 ? C1 : Min(X, C2) --> Max(C1, Min(X, C2)) | |||
5575 | // X > C1 ? C1 : Max(X, C2) --> Min(C1, Max(X, C2)) | |||
5576 | // and return description of the outer Max/Min. | |||
5577 | ||||
5578 | // First, check if select has inverse order: | |||
5579 | if (CmpRHS == FalseVal) { | |||
5580 | std::swap(TrueVal, FalseVal); | |||
5581 | Pred = CmpInst::getInversePredicate(Pred); | |||
5582 | } | |||
5583 | ||||
5584 | // Assume success now. If there's no match, callers should not use these anyway. | |||
5585 | LHS = TrueVal; | |||
5586 | RHS = FalseVal; | |||
5587 | ||||
5588 | const APFloat *FC1; | |||
5589 | if (CmpRHS != TrueVal || !match(CmpRHS, m_APFloat(FC1)) || !FC1->isFinite()) | |||
5590 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5591 | ||||
5592 | const APFloat *FC2; | |||
5593 | switch (Pred) { | |||
5594 | case CmpInst::FCMP_OLT: | |||
5595 | case CmpInst::FCMP_OLE: | |||
5596 | case CmpInst::FCMP_ULT: | |||
5597 | case CmpInst::FCMP_ULE: | |||
5598 | if (match(FalseVal, | |||
5599 | m_CombineOr(m_OrdFMin(m_Specific(CmpLHS), m_APFloat(FC2)), | |||
5600 | m_UnordFMin(m_Specific(CmpLHS), m_APFloat(FC2)))) && | |||
5601 | *FC1 < *FC2) | |||
5602 | return {SPF_FMAXNUM, SPNB_RETURNS_ANY, false}; | |||
5603 | break; | |||
5604 | case CmpInst::FCMP_OGT: | |||
5605 | case CmpInst::FCMP_OGE: | |||
5606 | case CmpInst::FCMP_UGT: | |||
5607 | case CmpInst::FCMP_UGE: | |||
5608 | if (match(FalseVal, | |||
5609 | m_CombineOr(m_OrdFMax(m_Specific(CmpLHS), m_APFloat(FC2)), | |||
5610 | m_UnordFMax(m_Specific(CmpLHS), m_APFloat(FC2)))) && | |||
5611 | *FC1 > *FC2) | |||
5612 | return {SPF_FMINNUM, SPNB_RETURNS_ANY, false}; | |||
5613 | break; | |||
5614 | default: | |||
5615 | break; | |||
5616 | } | |||
5617 | ||||
5618 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5619 | } | |||
5620 | ||||
5621 | /// Recognize variations of: | |||
5622 | /// CLAMP(v,l,h) ==> ((v) < (l) ? (l) : ((v) > (h) ? (h) : (v))) | |||
5623 | static SelectPatternResult matchClamp(CmpInst::Predicate Pred, | |||
5624 | Value *CmpLHS, Value *CmpRHS, | |||
5625 | Value *TrueVal, Value *FalseVal) { | |||
5626 | // Swap the select operands and predicate to match the patterns below. | |||
5627 | if (CmpRHS != TrueVal) { | |||
5628 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
5629 | std::swap(TrueVal, FalseVal); | |||
5630 | } | |||
5631 | const APInt *C1; | |||
5632 | if (CmpRHS == TrueVal && match(CmpRHS, m_APInt(C1))) { | |||
5633 | const APInt *C2; | |||
5634 | // (X <s C1) ? C1 : SMIN(X, C2) ==> SMAX(SMIN(X, C2), C1) | |||
5635 | if (match(FalseVal, m_SMin(m_Specific(CmpLHS), m_APInt(C2))) && | |||
5636 | C1->slt(*C2) && Pred == CmpInst::ICMP_SLT) | |||
5637 | return {SPF_SMAX, SPNB_NA, false}; | |||
5638 | ||||
5639 | // (X >s C1) ? C1 : SMAX(X, C2) ==> SMIN(SMAX(X, C2), C1) | |||
5640 | if (match(FalseVal, m_SMax(m_Specific(CmpLHS), m_APInt(C2))) && | |||
5641 | C1->sgt(*C2) && Pred == CmpInst::ICMP_SGT) | |||
5642 | return {SPF_SMIN, SPNB_NA, false}; | |||
5643 | ||||
5644 | // (X <u C1) ? C1 : UMIN(X, C2) ==> UMAX(UMIN(X, C2), C1) | |||
5645 | if (match(FalseVal, m_UMin(m_Specific(CmpLHS), m_APInt(C2))) && | |||
5646 | C1->ult(*C2) && Pred == CmpInst::ICMP_ULT) | |||
5647 | return {SPF_UMAX, SPNB_NA, false}; | |||
5648 | ||||
5649 | // (X >u C1) ? C1 : UMAX(X, C2) ==> UMIN(UMAX(X, C2), C1) | |||
5650 | if (match(FalseVal, m_UMax(m_Specific(CmpLHS), m_APInt(C2))) && | |||
5651 | C1->ugt(*C2) && Pred == CmpInst::ICMP_UGT) | |||
5652 | return {SPF_UMIN, SPNB_NA, false}; | |||
5653 | } | |||
5654 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5655 | } | |||
5656 | ||||
5657 | /// Recognize variations of: | |||
5658 | /// a < c ? min(a,b) : min(b,c) ==> min(min(a,b),min(b,c)) | |||
5659 | static SelectPatternResult matchMinMaxOfMinMax(CmpInst::Predicate Pred, | |||
5660 | Value *CmpLHS, Value *CmpRHS, | |||
5661 | Value *TVal, Value *FVal, | |||
5662 | unsigned Depth) { | |||
5663 | // TODO: Allow FP min/max with nnan/nsz. | |||
5664 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 5664, __extension__ __PRETTY_FUNCTION__)); | |||
5665 | ||||
5666 | Value *A = nullptr, *B = nullptr; | |||
5667 | SelectPatternResult L = matchSelectPattern(TVal, A, B, nullptr, Depth + 1); | |||
5668 | if (!SelectPatternResult::isMinOrMax(L.Flavor)) | |||
5669 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5670 | ||||
5671 | Value *C = nullptr, *D = nullptr; | |||
5672 | SelectPatternResult R = matchSelectPattern(FVal, C, D, nullptr, Depth + 1); | |||
5673 | if (L.Flavor != R.Flavor) | |||
5674 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5675 | ||||
5676 | // We have something like: x Pred y ? min(a, b) : min(c, d). | |||
5677 | // Try to match the compare to the min/max operations of the select operands. | |||
5678 | // First, make sure we have the right compare predicate. | |||
5679 | switch (L.Flavor) { | |||
5680 | case SPF_SMIN: | |||
5681 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) { | |||
5682 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
5683 | std::swap(CmpLHS, CmpRHS); | |||
5684 | } | |||
5685 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) | |||
5686 | break; | |||
5687 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5688 | case SPF_SMAX: | |||
5689 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) { | |||
5690 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
5691 | std::swap(CmpLHS, CmpRHS); | |||
5692 | } | |||
5693 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) | |||
5694 | break; | |||
5695 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5696 | case SPF_UMIN: | |||
5697 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) { | |||
5698 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
5699 | std::swap(CmpLHS, CmpRHS); | |||
5700 | } | |||
5701 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) | |||
5702 | break; | |||
5703 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5704 | case SPF_UMAX: | |||
5705 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { | |||
5706 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
5707 | std::swap(CmpLHS, CmpRHS); | |||
5708 | } | |||
5709 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) | |||
5710 | break; | |||
5711 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5712 | default: | |||
5713 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5714 | } | |||
5715 | ||||
5716 | // If there is a common operand in the already matched min/max and the other | |||
5717 | // min/max operands match the compare operands (either directly or inverted), | |||
5718 | // then this is min/max of the same flavor. | |||
5719 | ||||
5720 | // a pred c ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) | |||
5721 | // ~c pred ~a ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) | |||
5722 | if (D == B) { | |||
5723 | if ((CmpLHS == A && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && | |||
5724 | match(A, m_Not(m_Specific(CmpRHS))))) | |||
5725 | return {L.Flavor, SPNB_NA, false}; | |||
5726 | } | |||
5727 | // a pred d ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) | |||
5728 | // ~d pred ~a ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) | |||
5729 | if (C == B) { | |||
5730 | if ((CmpLHS == A && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && | |||
5731 | match(A, m_Not(m_Specific(CmpRHS))))) | |||
5732 | return {L.Flavor, SPNB_NA, false}; | |||
5733 | } | |||
5734 | // b pred c ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) | |||
5735 | // ~c pred ~b ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) | |||
5736 | if (D == A) { | |||
5737 | if ((CmpLHS == B && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && | |||
5738 | match(B, m_Not(m_Specific(CmpRHS))))) | |||
5739 | return {L.Flavor, SPNB_NA, false}; | |||
5740 | } | |||
5741 | // b pred d ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) | |||
5742 | // ~d pred ~b ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) | |||
5743 | if (C == A) { | |||
5744 | if ((CmpLHS == B && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && | |||
5745 | match(B, m_Not(m_Specific(CmpRHS))))) | |||
5746 | return {L.Flavor, SPNB_NA, false}; | |||
5747 | } | |||
5748 | ||||
5749 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5750 | } | |||
5751 | ||||
5752 | /// If the input value is the result of a 'not' op, constant integer, or vector | |||
5753 | /// splat of a constant integer, return the bitwise-not source value. | |||
5754 | /// TODO: This could be extended to handle non-splat vector integer constants. | |||
5755 | static Value *getNotValue(Value *V) { | |||
5756 | Value *NotV; | |||
5757 | if (match(V, m_Not(m_Value(NotV)))) | |||
5758 | return NotV; | |||
5759 | ||||
5760 | const APInt *C; | |||
5761 | if (match(V, m_APInt(C))) | |||
5762 | return ConstantInt::get(V->getType(), ~(*C)); | |||
5763 | ||||
5764 | return nullptr; | |||
5765 | } | |||
5766 | ||||
5767 | /// Match non-obvious integer minimum and maximum sequences. | |||
5768 | static SelectPatternResult matchMinMax(CmpInst::Predicate Pred, | |||
5769 | Value *CmpLHS, Value *CmpRHS, | |||
5770 | Value *TrueVal, Value *FalseVal, | |||
5771 | Value *&LHS, Value *&RHS, | |||
5772 | unsigned Depth) { | |||
5773 | // Assume success. If there's no match, callers should not use these anyway. | |||
5774 | LHS = TrueVal; | |||
5775 | RHS = FalseVal; | |||
5776 | ||||
5777 | SelectPatternResult SPR = matchClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal); | |||
5778 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) | |||
5779 | return SPR; | |||
5780 | ||||
5781 | SPR = matchMinMaxOfMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, Depth); | |||
5782 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) | |||
5783 | return SPR; | |||
5784 | ||||
5785 | // Look through 'not' ops to find disguised min/max. | |||
5786 | // (X > Y) ? ~X : ~Y ==> (~X < ~Y) ? ~X : ~Y ==> MIN(~X, ~Y) | |||
5787 | // (X < Y) ? ~X : ~Y ==> (~X > ~Y) ? ~X : ~Y ==> MAX(~X, ~Y) | |||
5788 | if (CmpLHS == getNotValue(TrueVal) && CmpRHS == getNotValue(FalseVal)) { | |||
5789 | switch (Pred) { | |||
5790 | case CmpInst::ICMP_SGT: return {SPF_SMIN, SPNB_NA, false}; | |||
5791 | case CmpInst::ICMP_SLT: return {SPF_SMAX, SPNB_NA, false}; | |||
5792 | case CmpInst::ICMP_UGT: return {SPF_UMIN, SPNB_NA, false}; | |||
5793 | case CmpInst::ICMP_ULT: return {SPF_UMAX, SPNB_NA, false}; | |||
5794 | default: break; | |||
5795 | } | |||
5796 | } | |||
5797 | ||||
5798 | // (X > Y) ? ~Y : ~X ==> (~X < ~Y) ? ~Y : ~X ==> MAX(~Y, ~X) | |||
5799 | // (X < Y) ? ~Y : ~X ==> (~X > ~Y) ? ~Y : ~X ==> MIN(~Y, ~X) | |||
5800 | if (CmpLHS == getNotValue(FalseVal) && CmpRHS == getNotValue(TrueVal)) { | |||
5801 | switch (Pred) { | |||
5802 | case CmpInst::ICMP_SGT: return {SPF_SMAX, SPNB_NA, false}; | |||
5803 | case CmpInst::ICMP_SLT: return {SPF_SMIN, SPNB_NA, false}; | |||
5804 | case CmpInst::ICMP_UGT: return {SPF_UMAX, SPNB_NA, false}; | |||
5805 | case CmpInst::ICMP_ULT: return {SPF_UMIN, SPNB_NA, false}; | |||
5806 | default: break; | |||
5807 | } | |||
5808 | } | |||
5809 | ||||
5810 | if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT) | |||
5811 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5812 | ||||
5813 | // Z = X -nsw Y | |||
5814 | // (X >s Y) ? 0 : Z ==> (Z >s 0) ? 0 : Z ==> SMIN(Z, 0) | |||
5815 | // (X <s Y) ? 0 : Z ==> (Z <s 0) ? 0 : Z ==> SMAX(Z, 0) | |||
5816 | if (match(TrueVal, m_Zero()) && | |||
5817 | match(FalseVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS)))) | |||
5818 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false}; | |||
5819 | ||||
5820 | // Z = X -nsw Y | |||
5821 | // (X >s Y) ? Z : 0 ==> (Z >s 0) ? Z : 0 ==> SMAX(Z, 0) | |||
5822 | // (X <s Y) ? Z : 0 ==> (Z <s 0) ? Z : 0 ==> SMIN(Z, 0) | |||
5823 | if (match(FalseVal, m_Zero()) && | |||
5824 | match(TrueVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS)))) | |||
5825 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false}; | |||
5826 | ||||
5827 | const APInt *C1; | |||
5828 | if (!match(CmpRHS, m_APInt(C1))) | |||
5829 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5830 | ||||
5831 | // An unsigned min/max can be written with a signed compare. | |||
5832 | const APInt *C2; | |||
5833 | if ((CmpLHS == TrueVal && match(FalseVal, m_APInt(C2))) || | |||
5834 | (CmpLHS == FalseVal && match(TrueVal, m_APInt(C2)))) { | |||
5835 | // Is the sign bit set? | |||
5836 | // (X <s 0) ? X : MAXVAL ==> (X >u MAXVAL) ? X : MAXVAL ==> UMAX | |||
5837 | // (X <s 0) ? MAXVAL : X ==> (X >u MAXVAL) ? MAXVAL : X ==> UMIN | |||
5838 | if (Pred == CmpInst::ICMP_SLT && C1->isNullValue() && | |||
5839 | C2->isMaxSignedValue()) | |||
5840 | return {CmpLHS == TrueVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; | |||
5841 | ||||
5842 | // Is the sign bit clear? | |||
5843 | // (X >s -1) ? MINVAL : X ==> (X <u MINVAL) ? MINVAL : X ==> UMAX | |||
5844 | // (X >s -1) ? X : MINVAL ==> (X <u MINVAL) ? X : MINVAL ==> UMIN | |||
5845 | if (Pred == CmpInst::ICMP_SGT && C1->isAllOnesValue() && | |||
5846 | C2->isMinSignedValue()) | |||
5847 | return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; | |||
5848 | } | |||
5849 | ||||
5850 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5851 | } | |||
5852 | ||||
5853 | bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW) { | |||
5854 | assert(X && Y && "Invalid operand")(static_cast <bool> (X && Y && "Invalid operand" ) ? void (0) : __assert_fail ("X && Y && \"Invalid operand\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 5854, __extension__ __PRETTY_FUNCTION__)); | |||
5855 | ||||
5856 | // X = sub (0, Y) || X = sub nsw (0, Y) | |||
5857 | if ((!NeedNSW && match(X, m_Sub(m_ZeroInt(), m_Specific(Y)))) || | |||
5858 | (NeedNSW && match(X, m_NSWSub(m_ZeroInt(), m_Specific(Y))))) | |||
5859 | return true; | |||
5860 | ||||
5861 | // Y = sub (0, X) || Y = sub nsw (0, X) | |||
5862 | if ((!NeedNSW && match(Y, m_Sub(m_ZeroInt(), m_Specific(X)))) || | |||
5863 | (NeedNSW && match(Y, m_NSWSub(m_ZeroInt(), m_Specific(X))))) | |||
5864 | return true; | |||
5865 | ||||
5866 | // X = sub (A, B), Y = sub (B, A) || X = sub nsw (A, B), Y = sub nsw (B, A) | |||
5867 | Value *A, *B; | |||
5868 | return (!NeedNSW && (match(X, m_Sub(m_Value(A), m_Value(B))) && | |||
5869 | match(Y, m_Sub(m_Specific(B), m_Specific(A))))) || | |||
5870 | (NeedNSW && (match(X, m_NSWSub(m_Value(A), m_Value(B))) && | |||
5871 | match(Y, m_NSWSub(m_Specific(B), m_Specific(A))))); | |||
5872 | } | |||
5873 | ||||
5874 | static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred, | |||
5875 | FastMathFlags FMF, | |||
5876 | Value *CmpLHS, Value *CmpRHS, | |||
5877 | Value *TrueVal, Value *FalseVal, | |||
5878 | Value *&LHS, Value *&RHS, | |||
5879 | unsigned Depth) { | |||
5880 | if (CmpInst::isFPPredicate(Pred)) { | |||
5881 | // IEEE-754 ignores the sign of 0.0 in comparisons. So if the select has one | |||
5882 | // 0.0 operand, set the compare's 0.0 operands to that same value for the | |||
5883 | // purpose of identifying min/max. Disregard vector constants with undefined | |||
5884 | // elements because those can not be back-propagated for analysis. | |||
5885 | Value *OutputZeroVal = nullptr; | |||
5886 | if (match(TrueVal, m_AnyZeroFP()) && !match(FalseVal, m_AnyZeroFP()) && | |||
5887 | !cast<Constant>(TrueVal)->containsUndefOrPoisonElement()) | |||
5888 | OutputZeroVal = TrueVal; | |||
5889 | else if (match(FalseVal, m_AnyZeroFP()) && !match(TrueVal, m_AnyZeroFP()) && | |||
5890 | !cast<Constant>(FalseVal)->containsUndefOrPoisonElement()) | |||
5891 | OutputZeroVal = FalseVal; | |||
5892 | ||||
5893 | if (OutputZeroVal) { | |||
5894 | if (match(CmpLHS, m_AnyZeroFP())) | |||
5895 | CmpLHS = OutputZeroVal; | |||
5896 | if (match(CmpRHS, m_AnyZeroFP())) | |||
5897 | CmpRHS = OutputZeroVal; | |||
5898 | } | |||
5899 | } | |||
5900 | ||||
5901 | LHS = CmpLHS; | |||
5902 | RHS = CmpRHS; | |||
5903 | ||||
5904 | // Signed zero may return inconsistent results between implementations. | |||
5905 | // (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0 | |||
5906 | // minNum(0.0, -0.0) // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1) | |||
5907 | // Therefore, we behave conservatively and only proceed if at least one of the | |||
5908 | // operands is known to not be zero or if we don't care about signed zero. | |||
5909 | switch (Pred) { | |||
5910 | default: break; | |||
5911 | // FIXME: Include OGT/OLT/UGT/ULT. | |||
5912 | case CmpInst::FCMP_OGE: case CmpInst::FCMP_OLE: | |||
5913 | case CmpInst::FCMP_UGE: case CmpInst::FCMP_ULE: | |||
5914 | if (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && | |||
5915 | !isKnownNonZero(CmpRHS)) | |||
5916 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5917 | } | |||
5918 | ||||
5919 | SelectPatternNaNBehavior NaNBehavior = SPNB_NA; | |||
5920 | bool Ordered = false; | |||
5921 | ||||
5922 | // When given one NaN and one non-NaN input: | |||
5923 | // - maxnum/minnum (C99 fmaxf()/fminf()) return the non-NaN input. | |||
5924 | // - A simple C99 (a < b ? a : b) construction will return 'b' (as the | |||
5925 | // ordered comparison fails), which could be NaN or non-NaN. | |||
5926 | // so here we discover exactly what NaN behavior is required/accepted. | |||
5927 | if (CmpInst::isFPPredicate(Pred)) { | |||
5928 | bool LHSSafe = isKnownNonNaN(CmpLHS, FMF); | |||
5929 | bool RHSSafe = isKnownNonNaN(CmpRHS, FMF); | |||
5930 | ||||
5931 | if (LHSSafe && RHSSafe) { | |||
5932 | // Both operands are known non-NaN. | |||
5933 | NaNBehavior = SPNB_RETURNS_ANY; | |||
5934 | } else if (CmpInst::isOrdered(Pred)) { | |||
5935 | // An ordered comparison will return false when given a NaN, so it | |||
5936 | // returns the RHS. | |||
5937 | Ordered = true; | |||
5938 | if (LHSSafe) | |||
5939 | // LHS is non-NaN, so if RHS is NaN then NaN will be returned. | |||
5940 | NaNBehavior = SPNB_RETURNS_NAN; | |||
5941 | else if (RHSSafe) | |||
5942 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
5943 | else | |||
5944 | // Completely unsafe. | |||
5945 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5946 | } else { | |||
5947 | Ordered = false; | |||
5948 | // An unordered comparison will return true when given a NaN, so it | |||
5949 | // returns the LHS. | |||
5950 | if (LHSSafe) | |||
5951 | // LHS is non-NaN, so if RHS is NaN then non-NaN will be returned. | |||
5952 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
5953 | else if (RHSSafe) | |||
5954 | NaNBehavior = SPNB_RETURNS_NAN; | |||
5955 | else | |||
5956 | // Completely unsafe. | |||
5957 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5958 | } | |||
5959 | } | |||
5960 | ||||
5961 | if (TrueVal == CmpRHS && FalseVal == CmpLHS) { | |||
5962 | std::swap(CmpLHS, CmpRHS); | |||
5963 | Pred = CmpInst::getSwappedPredicate(Pred); | |||
5964 | if (NaNBehavior == SPNB_RETURNS_NAN) | |||
5965 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
5966 | else if (NaNBehavior == SPNB_RETURNS_OTHER) | |||
5967 | NaNBehavior = SPNB_RETURNS_NAN; | |||
5968 | Ordered = !Ordered; | |||
5969 | } | |||
5970 | ||||
5971 | // ([if]cmp X, Y) ? X : Y | |||
5972 | if (TrueVal == CmpLHS && FalseVal == CmpRHS) { | |||
5973 | switch (Pred) { | |||
5974 | default: return {SPF_UNKNOWN, SPNB_NA, false}; // Equality. | |||
5975 | case ICmpInst::ICMP_UGT: | |||
5976 | case ICmpInst::ICMP_UGE: return {SPF_UMAX, SPNB_NA, false}; | |||
5977 | case ICmpInst::ICMP_SGT: | |||
5978 | case ICmpInst::ICMP_SGE: return {SPF_SMAX, SPNB_NA, false}; | |||
5979 | case ICmpInst::ICMP_ULT: | |||
5980 | case ICmpInst::ICMP_ULE: return {SPF_UMIN, SPNB_NA, false}; | |||
5981 | case ICmpInst::ICMP_SLT: | |||
5982 | case ICmpInst::ICMP_SLE: return {SPF_SMIN, SPNB_NA, false}; | |||
5983 | case FCmpInst::FCMP_UGT: | |||
5984 | case FCmpInst::FCMP_UGE: | |||
5985 | case FCmpInst::FCMP_OGT: | |||
5986 | case FCmpInst::FCMP_OGE: return {SPF_FMAXNUM, NaNBehavior, Ordered}; | |||
5987 | case FCmpInst::FCMP_ULT: | |||
5988 | case FCmpInst::FCMP_ULE: | |||
5989 | case FCmpInst::FCMP_OLT: | |||
5990 | case FCmpInst::FCMP_OLE: return {SPF_FMINNUM, NaNBehavior, Ordered}; | |||
5991 | } | |||
5992 | } | |||
5993 | ||||
5994 | if (isKnownNegation(TrueVal, FalseVal)) { | |||
5995 | // Sign-extending LHS does not change its sign, so TrueVal/FalseVal can | |||
5996 | // match against either LHS or sext(LHS). | |||
5997 | auto MaybeSExtCmpLHS = | |||
5998 | m_CombineOr(m_Specific(CmpLHS), m_SExt(m_Specific(CmpLHS))); | |||
5999 | auto ZeroOrAllOnes = m_CombineOr(m_ZeroInt(), m_AllOnes()); | |||
6000 | auto ZeroOrOne = m_CombineOr(m_ZeroInt(), m_One()); | |||
6001 | if (match(TrueVal, MaybeSExtCmpLHS)) { | |||
6002 | // Set the return values. If the compare uses the negated value (-X >s 0), | |||
6003 | // swap the return values because the negated value is always 'RHS'. | |||
6004 | LHS = TrueVal; | |||
6005 | RHS = FalseVal; | |||
6006 | if (match(CmpLHS, m_Neg(m_Specific(FalseVal)))) | |||
6007 | std::swap(LHS, RHS); | |||
6008 | ||||
6009 | // (X >s 0) ? X : -X or (X >s -1) ? X : -X --> ABS(X) | |||
6010 | // (-X >s 0) ? -X : X or (-X >s -1) ? -X : X --> ABS(X) | |||
6011 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) | |||
6012 | return {SPF_ABS, SPNB_NA, false}; | |||
6013 | ||||
6014 | // (X >=s 0) ? X : -X or (X >=s 1) ? X : -X --> ABS(X) | |||
6015 | if (Pred == ICmpInst::ICMP_SGE && match(CmpRHS, ZeroOrOne)) | |||
6016 | return {SPF_ABS, SPNB_NA, false}; | |||
6017 | ||||
6018 | // (X <s 0) ? X : -X or (X <s 1) ? X : -X --> NABS(X) | |||
6019 | // (-X <s 0) ? -X : X or (-X <s 1) ? -X : X --> NABS(X) | |||
6020 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) | |||
6021 | return {SPF_NABS, SPNB_NA, false}; | |||
6022 | } | |||
6023 | else if (match(FalseVal, MaybeSExtCmpLHS)) { | |||
6024 | // Set the return values. If the compare uses the negated value (-X >s 0), | |||
6025 | // swap the return values because the negated value is always 'RHS'. | |||
6026 | LHS = FalseVal; | |||
6027 | RHS = TrueVal; | |||
6028 | if (match(CmpLHS, m_Neg(m_Specific(TrueVal)))) | |||
6029 | std::swap(LHS, RHS); | |||
6030 | ||||
6031 | // (X >s 0) ? -X : X or (X >s -1) ? -X : X --> NABS(X) | |||
6032 | // (-X >s 0) ? X : -X or (-X >s -1) ? X : -X --> NABS(X) | |||
6033 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) | |||
6034 | return {SPF_NABS, SPNB_NA, false}; | |||
6035 | ||||
6036 | // (X <s 0) ? -X : X or (X <s 1) ? -X : X --> ABS(X) | |||
6037 | // (-X <s 0) ? X : -X or (-X <s 1) ? X : -X --> ABS(X) | |||
6038 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) | |||
6039 | return {SPF_ABS, SPNB_NA, false}; | |||
6040 | } | |||
6041 | } | |||
6042 | ||||
6043 | if (CmpInst::isIntPredicate(Pred)) | |||
6044 | return matchMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS, Depth); | |||
6045 | ||||
6046 | // According to (IEEE 754-2008 5.3.1), minNum(0.0, -0.0) and similar | |||
6047 | // may return either -0.0 or 0.0, so fcmp/select pair has stricter | |||
6048 | // semantics than minNum. Be conservative in such case. | |||
6049 | if (NaNBehavior != SPNB_RETURNS_ANY || | |||
6050 | (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && | |||
6051 | !isKnownNonZero(CmpRHS))) | |||
6052 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
6053 | ||||
6054 | return matchFastFloatClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS); | |||
6055 | } | |||
6056 | ||||
6057 | /// Helps to match a select pattern in case of a type mismatch. | |||
6058 | /// | |||
6059 | /// The function processes the case when type of true and false values of a | |||
6060 | /// select instruction differs from type of the cmp instruction operands because | |||
6061 | /// of a cast instruction. The function checks if it is legal to move the cast | |||
6062 | /// operation after "select". If yes, it returns the new second value of | |||
6063 | /// "select" (with the assumption that cast is moved): | |||
6064 | /// 1. As operand of cast instruction when both values of "select" are same cast | |||
6065 | /// instructions. | |||
6066 | /// 2. As restored constant (by applying reverse cast operation) when the first | |||
6067 | /// value of the "select" is a cast operation and the second value is a | |||
6068 | /// constant. | |||
6069 | /// NOTE: We return only the new second value because the first value could be | |||
6070 | /// accessed as operand of cast instruction. | |||
6071 | static Value *lookThroughCast(CmpInst *CmpI, Value *V1, Value *V2, | |||
6072 | Instruction::CastOps *CastOp) { | |||
6073 | auto *Cast1 = dyn_cast<CastInst>(V1); | |||
6074 | if (!Cast1) | |||
6075 | return nullptr; | |||
6076 | ||||
6077 | *CastOp = Cast1->getOpcode(); | |||
6078 | Type *SrcTy = Cast1->getSrcTy(); | |||
6079 | if (auto *Cast2 = dyn_cast<CastInst>(V2)) { | |||
6080 | // If V1 and V2 are both the same cast from the same type, look through V1. | |||
6081 | if (*CastOp == Cast2->getOpcode() && SrcTy == Cast2->getSrcTy()) | |||
6082 | return Cast2->getOperand(0); | |||
6083 | return nullptr; | |||
6084 | } | |||
6085 | ||||
6086 | auto *C = dyn_cast<Constant>(V2); | |||
6087 | if (!C) | |||
6088 | return nullptr; | |||
6089 | ||||
6090 | Constant *CastedTo = nullptr; | |||
6091 | switch (*CastOp) { | |||
6092 | case Instruction::ZExt: | |||
6093 | if (CmpI->isUnsigned()) | |||
6094 | CastedTo = ConstantExpr::getTrunc(C, SrcTy); | |||
6095 | break; | |||
6096 | case Instruction::SExt: | |||
6097 | if (CmpI->isSigned()) | |||
6098 | CastedTo = ConstantExpr::getTrunc(C, SrcTy, true); | |||
6099 | break; | |||
6100 | case Instruction::Trunc: | |||
6101 | Constant *CmpConst; | |||
6102 | if (match(CmpI->getOperand(1), m_Constant(CmpConst)) && | |||
6103 | CmpConst->getType() == SrcTy) { | |||
6104 | // Here we have the following case: | |||
6105 | // | |||
6106 | // %cond = cmp iN %x, CmpConst | |||
6107 | // %tr = trunc iN %x to iK | |||
6108 | // %narrowsel = select i1 %cond, iK %t, iK C | |||
6109 | // | |||
6110 | // We can always move trunc after select operation: | |||
6111 | // | |||
6112 | // %cond = cmp iN %x, CmpConst | |||
6113 | // %widesel = select i1 %cond, iN %x, iN CmpConst | |||
6114 | // %tr = trunc iN %widesel to iK | |||
6115 | // | |||
6116 | // Note that C could be extended in any way because we don't care about | |||
6117 | // upper bits after truncation. It can't be abs pattern, because it would | |||
6118 | // look like: | |||
6119 | // | |||
6120 | // select i1 %cond, x, -x. | |||
6121 | // | |||
6122 | // So only min/max pattern could be matched. Such match requires widened C | |||
6123 | // == CmpConst. That is why set widened C = CmpConst, condition trunc | |||
6124 | // CmpConst == C is checked below. | |||
6125 | CastedTo = CmpConst; | |||
6126 | } else { | |||
6127 | CastedTo = ConstantExpr::getIntegerCast(C, SrcTy, CmpI->isSigned()); | |||
6128 | } | |||
6129 | break; | |||
6130 | case Instruction::FPTrunc: | |||
6131 | CastedTo = ConstantExpr::getFPExtend(C, SrcTy, true); | |||
6132 | break; | |||
6133 | case Instruction::FPExt: | |||
6134 | CastedTo = ConstantExpr::getFPTrunc(C, SrcTy, true); | |||
6135 | break; | |||
6136 | case Instruction::FPToUI: | |||
6137 | CastedTo = ConstantExpr::getUIToFP(C, SrcTy, true); | |||
6138 | break; | |||
6139 | case Instruction::FPToSI: | |||
6140 | CastedTo = ConstantExpr::getSIToFP(C, SrcTy, true); | |||
6141 | break; | |||
6142 | case Instruction::UIToFP: | |||
6143 | CastedTo = ConstantExpr::getFPToUI(C, SrcTy, true); | |||
6144 | break; | |||
6145 | case Instruction::SIToFP: | |||
6146 | CastedTo = ConstantExpr::getFPToSI(C, SrcTy, true); | |||
6147 | break; | |||
6148 | default: | |||
6149 | break; | |||
6150 | } | |||
6151 | ||||
6152 | if (!CastedTo) | |||
6153 | return nullptr; | |||
6154 | ||||
6155 | // Make sure the cast doesn't lose any information. | |||
6156 | Constant *CastedBack = | |||
6157 | ConstantExpr::getCast(*CastOp, CastedTo, C->getType(), true); | |||
6158 | if (CastedBack != C) | |||
6159 | return nullptr; | |||
6160 | ||||
6161 | return CastedTo; | |||
6162 | } | |||
6163 | ||||
6164 | SelectPatternResult llvm::matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, | |||
6165 | Instruction::CastOps *CastOp, | |||
6166 | unsigned Depth) { | |||
6167 | if (Depth >= MaxAnalysisRecursionDepth) | |||
6168 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
6169 | ||||
6170 | SelectInst *SI = dyn_cast<SelectInst>(V); | |||
6171 | if (!SI) return {SPF_UNKNOWN, SPNB_NA, false}; | |||
6172 | ||||
6173 | CmpInst *CmpI = dyn_cast<CmpInst>(SI->getCondition()); | |||
6174 | if (!CmpI) return {SPF_UNKNOWN, SPNB_NA, false}; | |||
6175 | ||||
6176 | Value *TrueVal = SI->getTrueValue(); | |||
6177 | Value *FalseVal = SI->getFalseValue(); | |||
6178 | ||||
6179 | return llvm::matchDecomposedSelectPattern(CmpI, TrueVal, FalseVal, LHS, RHS, | |||
6180 | CastOp, Depth); | |||
6181 | } | |||
6182 | ||||
6183 | SelectPatternResult llvm::matchDecomposedSelectPattern( | |||
6184 | CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS, | |||
6185 | Instruction::CastOps *CastOp, unsigned Depth) { | |||
6186 | CmpInst::Predicate Pred = CmpI->getPredicate(); | |||
6187 | Value *CmpLHS = CmpI->getOperand(0); | |||
6188 | Value *CmpRHS = CmpI->getOperand(1); | |||
6189 | FastMathFlags FMF; | |||
6190 | if (isa<FPMathOperator>(CmpI)) | |||
6191 | FMF = CmpI->getFastMathFlags(); | |||
6192 | ||||
6193 | // Bail out early. | |||
6194 | if (CmpI->isEquality()) | |||
6195 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
6196 | ||||
6197 | // Deal with type mismatches. | |||
6198 | if (CastOp && CmpLHS->getType() != TrueVal->getType()) { | |||
6199 | if (Value *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp)) { | |||
6200 | // If this is a potential fmin/fmax with a cast to integer, then ignore | |||
6201 | // -0.0 because there is no corresponding integer value. | |||
6202 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) | |||
6203 | FMF.setNoSignedZeros(); | |||
6204 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, | |||
6205 | cast<CastInst>(TrueVal)->getOperand(0), C, | |||
6206 | LHS, RHS, Depth); | |||
6207 | } | |||
6208 | if (Value *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp)) { | |||
6209 | // If this is a potential fmin/fmax with a cast to integer, then ignore | |||
6210 | // -0.0 because there is no corresponding integer value. | |||
6211 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) | |||
6212 | FMF.setNoSignedZeros(); | |||
6213 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, | |||
6214 | C, cast<CastInst>(FalseVal)->getOperand(0), | |||
6215 | LHS, RHS, Depth); | |||
6216 | } | |||
6217 | } | |||
6218 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, TrueVal, FalseVal, | |||
6219 | LHS, RHS, Depth); | |||
6220 | } | |||
6221 | ||||
6222 | CmpInst::Predicate llvm::getMinMaxPred(SelectPatternFlavor SPF, bool Ordered) { | |||
6223 | if (SPF == SPF_SMIN) return ICmpInst::ICMP_SLT; | |||
6224 | if (SPF == SPF_UMIN) return ICmpInst::ICMP_ULT; | |||
6225 | if (SPF == SPF_SMAX) return ICmpInst::ICMP_SGT; | |||
6226 | if (SPF == SPF_UMAX) return ICmpInst::ICMP_UGT; | |||
6227 | if (SPF == SPF_FMINNUM) | |||
6228 | return Ordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; | |||
6229 | if (SPF == SPF_FMAXNUM) | |||
6230 | return Ordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; | |||
6231 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6231); | |||
6232 | } | |||
6233 | ||||
6234 | SelectPatternFlavor llvm::getInverseMinMaxFlavor(SelectPatternFlavor SPF) { | |||
6235 | if (SPF == SPF_SMIN) return SPF_SMAX; | |||
6236 | if (SPF == SPF_UMIN) return SPF_UMAX; | |||
6237 | if (SPF == SPF_SMAX) return SPF_SMIN; | |||
6238 | if (SPF == SPF_UMAX) return SPF_UMIN; | |||
6239 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6239); | |||
6240 | } | |||
6241 | ||||
6242 | Intrinsic::ID llvm::getInverseMinMaxIntrinsic(Intrinsic::ID MinMaxID) { | |||
6243 | switch (MinMaxID) { | |||
6244 | case Intrinsic::smax: return Intrinsic::smin; | |||
6245 | case Intrinsic::smin: return Intrinsic::smax; | |||
6246 | case Intrinsic::umax: return Intrinsic::umin; | |||
6247 | case Intrinsic::umin: return Intrinsic::umax; | |||
6248 | default: llvm_unreachable("Unexpected intrinsic")::llvm::llvm_unreachable_internal("Unexpected intrinsic", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6248); | |||
6249 | } | |||
6250 | } | |||
6251 | ||||
6252 | CmpInst::Predicate llvm::getInverseMinMaxPred(SelectPatternFlavor SPF) { | |||
6253 | return getMinMaxPred(getInverseMinMaxFlavor(SPF)); | |||
6254 | } | |||
6255 | ||||
6256 | APInt llvm::getMinMaxLimit(SelectPatternFlavor SPF, unsigned BitWidth) { | |||
6257 | switch (SPF) { | |||
6258 | case SPF_SMAX: return APInt::getSignedMaxValue(BitWidth); | |||
6259 | case SPF_SMIN: return APInt::getSignedMinValue(BitWidth); | |||
6260 | case SPF_UMAX: return APInt::getMaxValue(BitWidth); | |||
6261 | case SPF_UMIN: return APInt::getMinValue(BitWidth); | |||
6262 | default: llvm_unreachable("Unexpected flavor")::llvm::llvm_unreachable_internal("Unexpected flavor", "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6262); | |||
6263 | } | |||
6264 | } | |||
6265 | ||||
6266 | std::pair<Intrinsic::ID, bool> | |||
6267 | llvm::canConvertToMinOrMaxIntrinsic(ArrayRef<Value *> VL) { | |||
6268 | // Check if VL contains select instructions that can be folded into a min/max | |||
6269 | // vector intrinsic and return the intrinsic if it is possible. | |||
6270 | // TODO: Support floating point min/max. | |||
6271 | bool AllCmpSingleUse = true; | |||
6272 | SelectPatternResult SelectPattern; | |||
6273 | SelectPattern.Flavor = SPF_UNKNOWN; | |||
6274 | if (all_of(VL, [&SelectPattern, &AllCmpSingleUse](Value *I) { | |||
6275 | Value *LHS, *RHS; | |||
6276 | auto CurrentPattern = matchSelectPattern(I, LHS, RHS); | |||
6277 | if (!SelectPatternResult::isMinOrMax(CurrentPattern.Flavor) || | |||
6278 | CurrentPattern.Flavor == SPF_FMINNUM || | |||
6279 | CurrentPattern.Flavor == SPF_FMAXNUM || | |||
6280 | !I->getType()->isIntOrIntVectorTy()) | |||
6281 | return false; | |||
6282 | if (SelectPattern.Flavor != SPF_UNKNOWN && | |||
6283 | SelectPattern.Flavor != CurrentPattern.Flavor) | |||
6284 | return false; | |||
6285 | SelectPattern = CurrentPattern; | |||
6286 | AllCmpSingleUse &= | |||
6287 | match(I, m_Select(m_OneUse(m_Value()), m_Value(), m_Value())); | |||
6288 | return true; | |||
6289 | })) { | |||
6290 | switch (SelectPattern.Flavor) { | |||
6291 | case SPF_SMIN: | |||
6292 | return {Intrinsic::smin, AllCmpSingleUse}; | |||
6293 | case SPF_UMIN: | |||
6294 | return {Intrinsic::umin, AllCmpSingleUse}; | |||
6295 | case SPF_SMAX: | |||
6296 | return {Intrinsic::smax, AllCmpSingleUse}; | |||
6297 | case SPF_UMAX: | |||
6298 | return {Intrinsic::umax, AllCmpSingleUse}; | |||
6299 | default: | |||
6300 | llvm_unreachable("unexpected select pattern flavor")::llvm::llvm_unreachable_internal("unexpected select pattern flavor" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6300); | |||
6301 | } | |||
6302 | } | |||
6303 | return {Intrinsic::not_intrinsic, false}; | |||
6304 | } | |||
6305 | ||||
6306 | bool llvm::matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO, | |||
6307 | Value *&Start, Value *&Step) { | |||
6308 | // Handle the case of a simple two-predecessor recurrence PHI. | |||
6309 | // There's a lot more that could theoretically be done here, but | |||
6310 | // this is sufficient to catch some interesting cases. | |||
6311 | if (P->getNumIncomingValues() != 2) | |||
6312 | return false; | |||
6313 | ||||
6314 | for (unsigned i = 0; i != 2; ++i) { | |||
6315 | Value *L = P->getIncomingValue(i); | |||
6316 | Value *R = P->getIncomingValue(!i); | |||
6317 | Operator *LU = dyn_cast<Operator>(L); | |||
6318 | if (!LU) | |||
6319 | continue; | |||
6320 | unsigned Opcode = LU->getOpcode(); | |||
6321 | ||||
6322 | switch (Opcode) { | |||
6323 | default: | |||
6324 | continue; | |||
6325 | // TODO: Expand list -- xor, div, gep, uaddo, etc.. | |||
6326 | case Instruction::LShr: | |||
6327 | case Instruction::AShr: | |||
6328 | case Instruction::Shl: | |||
6329 | case Instruction::Add: | |||
6330 | case Instruction::Sub: | |||
6331 | case Instruction::And: | |||
6332 | case Instruction::Or: | |||
6333 | case Instruction::Mul: { | |||
6334 | Value *LL = LU->getOperand(0); | |||
6335 | Value *LR = LU->getOperand(1); | |||
6336 | // Find a recurrence. | |||
6337 | if (LL == P) | |||
6338 | L = LR; | |||
6339 | else if (LR == P) | |||
6340 | L = LL; | |||
6341 | else | |||
6342 | continue; // Check for recurrence with L and R flipped. | |||
6343 | ||||
6344 | break; // Match! | |||
6345 | } | |||
6346 | }; | |||
6347 | ||||
6348 | // We have matched a recurrence of the form: | |||
6349 | // %iv = [R, %entry], [%iv.next, %backedge] | |||
6350 | // %iv.next = binop %iv, L | |||
6351 | // OR | |||
6352 | // %iv = [R, %entry], [%iv.next, %backedge] | |||
6353 | // %iv.next = binop L, %iv | |||
6354 | BO = cast<BinaryOperator>(LU); | |||
6355 | Start = R; | |||
6356 | Step = L; | |||
6357 | return true; | |||
6358 | } | |||
6359 | return false; | |||
6360 | } | |||
6361 | ||||
6362 | bool llvm::matchSimpleRecurrence(const BinaryOperator *I, PHINode *&P, | |||
6363 | Value *&Start, Value *&Step) { | |||
6364 | BinaryOperator *BO = nullptr; | |||
6365 | P = dyn_cast<PHINode>(I->getOperand(0)); | |||
6366 | if (!P) | |||
6367 | P = dyn_cast<PHINode>(I->getOperand(1)); | |||
6368 | return P && matchSimpleRecurrence(P, BO, Start, Step) && BO == I; | |||
6369 | } | |||
6370 | ||||
6371 | /// Return true if "icmp Pred LHS RHS" is always true. | |||
6372 | static bool isTruePredicate(CmpInst::Predicate Pred, const Value *LHS, | |||
6373 | const Value *RHS, const DataLayout &DL, | |||
6374 | unsigned Depth) { | |||
6375 | assert(!LHS->getType()->isVectorTy() && "TODO: extend to handle vectors!")(static_cast <bool> (!LHS->getType()->isVectorTy( ) && "TODO: extend to handle vectors!") ? void (0) : __assert_fail ("!LHS->getType()->isVectorTy() && \"TODO: extend to handle vectors!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6375, __extension__ __PRETTY_FUNCTION__)); | |||
6376 | if (ICmpInst::isTrueWhenEqual(Pred) && LHS == RHS) | |||
6377 | return true; | |||
6378 | ||||
6379 | switch (Pred) { | |||
6380 | default: | |||
6381 | return false; | |||
6382 | ||||
6383 | case CmpInst::ICMP_SLE: { | |||
6384 | const APInt *C; | |||
6385 | ||||
6386 | // LHS s<= LHS +_{nsw} C if C >= 0 | |||
6387 | if (match(RHS, m_NSWAdd(m_Specific(LHS), m_APInt(C)))) | |||
6388 | return !C->isNegative(); | |||
6389 | return false; | |||
6390 | } | |||
6391 | ||||
6392 | case CmpInst::ICMP_ULE: { | |||
6393 | const APInt *C; | |||
6394 | ||||
6395 | // LHS u<= LHS +_{nuw} C for any C | |||
6396 | if (match(RHS, m_NUWAdd(m_Specific(LHS), m_APInt(C)))) | |||
6397 | return true; | |||
6398 | ||||
6399 | // Match A to (X +_{nuw} CA) and B to (X +_{nuw} CB) | |||
6400 | auto MatchNUWAddsToSameValue = [&](const Value *A, const Value *B, | |||
6401 | const Value *&X, | |||
6402 | const APInt *&CA, const APInt *&CB) { | |||
6403 | if (match(A, m_NUWAdd(m_Value(X), m_APInt(CA))) && | |||
6404 | match(B, m_NUWAdd(m_Specific(X), m_APInt(CB)))) | |||
6405 | return true; | |||
6406 | ||||
6407 | // If X & C == 0 then (X | C) == X +_{nuw} C | |||
6408 | if (match(A, m_Or(m_Value(X), m_APInt(CA))) && | |||
6409 | match(B, m_Or(m_Specific(X), m_APInt(CB)))) { | |||
6410 | KnownBits Known(CA->getBitWidth()); | |||
6411 | computeKnownBits(X, Known, DL, Depth + 1, /*AC*/ nullptr, | |||
6412 | /*CxtI*/ nullptr, /*DT*/ nullptr); | |||
6413 | if (CA->isSubsetOf(Known.Zero) && CB->isSubsetOf(Known.Zero)) | |||
6414 | return true; | |||
6415 | } | |||
6416 | ||||
6417 | return false; | |||
6418 | }; | |||
6419 | ||||
6420 | const Value *X; | |||
6421 | const APInt *CLHS, *CRHS; | |||
6422 | if (MatchNUWAddsToSameValue(LHS, RHS, X, CLHS, CRHS)) | |||
6423 | return CLHS->ule(*CRHS); | |||
6424 | ||||
6425 | return false; | |||
6426 | } | |||
6427 | } | |||
6428 | } | |||
6429 | ||||
6430 | /// Return true if "icmp Pred BLHS BRHS" is true whenever "icmp Pred | |||
6431 | /// ALHS ARHS" is true. Otherwise, return None. | |||
6432 | static Optional<bool> | |||
6433 | isImpliedCondOperands(CmpInst::Predicate Pred, const Value *ALHS, | |||
6434 | const Value *ARHS, const Value *BLHS, const Value *BRHS, | |||
6435 | const DataLayout &DL, unsigned Depth) { | |||
6436 | switch (Pred) { | |||
6437 | default: | |||
6438 | return None; | |||
6439 | ||||
6440 | case CmpInst::ICMP_SLT: | |||
6441 | case CmpInst::ICMP_SLE: | |||
6442 | if (isTruePredicate(CmpInst::ICMP_SLE, BLHS, ALHS, DL, Depth) && | |||
6443 | isTruePredicate(CmpInst::ICMP_SLE, ARHS, BRHS, DL, Depth)) | |||
6444 | return true; | |||
6445 | return None; | |||
6446 | ||||
6447 | case CmpInst::ICMP_ULT: | |||
6448 | case CmpInst::ICMP_ULE: | |||
6449 | if (isTruePredicate(CmpInst::ICMP_ULE, BLHS, ALHS, DL, Depth) && | |||
6450 | isTruePredicate(CmpInst::ICMP_ULE, ARHS, BRHS, DL, Depth)) | |||
6451 | return true; | |||
6452 | return None; | |||
6453 | } | |||
6454 | } | |||
6455 | ||||
6456 | /// Return true if the operands of the two compares match. IsSwappedOps is true | |||
6457 | /// when the operands match, but are swapped. | |||
6458 | static bool isMatchingOps(const Value *ALHS, const Value *ARHS, | |||
6459 | const Value *BLHS, const Value *BRHS, | |||
6460 | bool &IsSwappedOps) { | |||
6461 | ||||
6462 | bool IsMatchingOps = (ALHS == BLHS && ARHS == BRHS); | |||
6463 | IsSwappedOps = (ALHS == BRHS && ARHS == BLHS); | |||
6464 | return IsMatchingOps || IsSwappedOps; | |||
6465 | } | |||
6466 | ||||
6467 | /// Return true if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is true. | |||
6468 | /// Return false if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is false. | |||
6469 | /// Otherwise, return None if we can't infer anything. | |||
6470 | static Optional<bool> isImpliedCondMatchingOperands(CmpInst::Predicate APred, | |||
6471 | CmpInst::Predicate BPred, | |||
6472 | bool AreSwappedOps) { | |||
6473 | // Canonicalize the predicate as if the operands were not commuted. | |||
6474 | if (AreSwappedOps) | |||
6475 | BPred = ICmpInst::getSwappedPredicate(BPred); | |||
6476 | ||||
6477 | if (CmpInst::isImpliedTrueByMatchingCmp(APred, BPred)) | |||
6478 | return true; | |||
6479 | if (CmpInst::isImpliedFalseByMatchingCmp(APred, BPred)) | |||
6480 | return false; | |||
6481 | ||||
6482 | return None; | |||
6483 | } | |||
6484 | ||||
6485 | /// Return true if "icmp APred X, C1" implies "icmp BPred X, C2" is true. | |||
6486 | /// Return false if "icmp APred X, C1" implies "icmp BPred X, C2" is false. | |||
6487 | /// Otherwise, return None if we can't infer anything. | |||
6488 | static Optional<bool> | |||
6489 | isImpliedCondMatchingImmOperands(CmpInst::Predicate APred, | |||
6490 | const ConstantInt *C1, | |||
6491 | CmpInst::Predicate BPred, | |||
6492 | const ConstantInt *C2) { | |||
6493 | ConstantRange DomCR = | |||
6494 | ConstantRange::makeExactICmpRegion(APred, C1->getValue()); | |||
6495 | ConstantRange CR = ConstantRange::makeExactICmpRegion(BPred, C2->getValue()); | |||
6496 | ConstantRange Intersection = DomCR.intersectWith(CR); | |||
6497 | ConstantRange Difference = DomCR.difference(CR); | |||
6498 | if (Intersection.isEmptySet()) | |||
6499 | return false; | |||
6500 | if (Difference.isEmptySet()) | |||
6501 | return true; | |||
6502 | return None; | |||
6503 | } | |||
6504 | ||||
6505 | /// Return true if LHS implies RHS is true. Return false if LHS implies RHS is | |||
6506 | /// false. Otherwise, return None if we can't infer anything. | |||
6507 | static Optional<bool> isImpliedCondICmps(const ICmpInst *LHS, | |||
6508 | CmpInst::Predicate BPred, | |||
6509 | const Value *BLHS, const Value *BRHS, | |||
6510 | const DataLayout &DL, bool LHSIsTrue, | |||
6511 | unsigned Depth) { | |||
6512 | Value *ALHS = LHS->getOperand(0); | |||
6513 | Value *ARHS = LHS->getOperand(1); | |||
6514 | ||||
6515 | // The rest of the logic assumes the LHS condition is true. If that's not the | |||
6516 | // case, invert the predicate to make it so. | |||
6517 | CmpInst::Predicate APred = | |||
6518 | LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate(); | |||
6519 | ||||
6520 | // Can we infer anything when the two compares have matching operands? | |||
6521 | bool AreSwappedOps; | |||
6522 | if (isMatchingOps(ALHS, ARHS, BLHS, BRHS, AreSwappedOps)) { | |||
6523 | if (Optional<bool> Implication = isImpliedCondMatchingOperands( | |||
6524 | APred, BPred, AreSwappedOps)) | |||
6525 | return Implication; | |||
6526 | // No amount of additional analysis will infer the second condition, so | |||
6527 | // early exit. | |||
6528 | return None; | |||
6529 | } | |||
6530 | ||||
6531 | // Can we infer anything when the LHS operands match and the RHS operands are | |||
6532 | // constants (not necessarily matching)? | |||
6533 | if (ALHS == BLHS && isa<ConstantInt>(ARHS) && isa<ConstantInt>(BRHS)) { | |||
6534 | if (Optional<bool> Implication = isImpliedCondMatchingImmOperands( | |||
6535 | APred, cast<ConstantInt>(ARHS), BPred, cast<ConstantInt>(BRHS))) | |||
6536 | return Implication; | |||
6537 | // No amount of additional analysis will infer the second condition, so | |||
6538 | // early exit. | |||
6539 | return None; | |||
6540 | } | |||
6541 | ||||
6542 | if (APred == BPred) | |||
6543 | return isImpliedCondOperands(APred, ALHS, ARHS, BLHS, BRHS, DL, Depth); | |||
6544 | return None; | |||
6545 | } | |||
6546 | ||||
6547 | /// Return true if LHS implies RHS is true. Return false if LHS implies RHS is | |||
6548 | /// false. Otherwise, return None if we can't infer anything. We expect the | |||
6549 | /// RHS to be an icmp and the LHS to be an 'and', 'or', or a 'select' instruction. | |||
6550 | static Optional<bool> | |||
6551 | isImpliedCondAndOr(const Instruction *LHS, CmpInst::Predicate RHSPred, | |||
6552 | const Value *RHSOp0, const Value *RHSOp1, | |||
6553 | const DataLayout &DL, bool LHSIsTrue, unsigned Depth) { | |||
6554 | // The LHS must be an 'or', 'and', or a 'select' instruction. | |||
6555 | 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'.\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6558, __extension__ __PRETTY_FUNCTION__)) | |||
6556 | 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'.\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6558, __extension__ __PRETTY_FUNCTION__)) | |||
6557 | 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'.\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6558, __extension__ __PRETTY_FUNCTION__)) | |||
6558 | "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'.\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6558, __extension__ __PRETTY_FUNCTION__)); | |||
6559 | ||||
6560 | assert(Depth <= MaxAnalysisRecursionDepth && "Hit recursion limit")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth && "Hit recursion limit") ? void (0) : __assert_fail ("Depth <= MaxAnalysisRecursionDepth && \"Hit recursion limit\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6560, __extension__ __PRETTY_FUNCTION__)); | |||
6561 | ||||
6562 | // If the result of an 'or' is false, then we know both legs of the 'or' are | |||
6563 | // false. Similarly, if the result of an 'and' is true, then we know both | |||
6564 | // legs of the 'and' are true. | |||
6565 | const Value *ALHS, *ARHS; | |||
6566 | if ((!LHSIsTrue && match(LHS, m_LogicalOr(m_Value(ALHS), m_Value(ARHS)))) || | |||
6567 | (LHSIsTrue && match(LHS, m_LogicalAnd(m_Value(ALHS), m_Value(ARHS))))) { | |||
6568 | // FIXME: Make this non-recursion. | |||
6569 | if (Optional<bool> Implication = isImpliedCondition( | |||
6570 | ALHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1)) | |||
6571 | return Implication; | |||
6572 | if (Optional<bool> Implication = isImpliedCondition( | |||
6573 | ARHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1)) | |||
6574 | return Implication; | |||
6575 | return None; | |||
6576 | } | |||
6577 | return None; | |||
6578 | } | |||
6579 | ||||
6580 | Optional<bool> | |||
6581 | llvm::isImpliedCondition(const Value *LHS, CmpInst::Predicate RHSPred, | |||
6582 | const Value *RHSOp0, const Value *RHSOp1, | |||
6583 | const DataLayout &DL, bool LHSIsTrue, unsigned Depth) { | |||
6584 | // Bail out when we hit the limit. | |||
6585 | if (Depth == MaxAnalysisRecursionDepth) | |||
6586 | return None; | |||
6587 | ||||
6588 | // A mismatch occurs when we compare a scalar cmp to a vector cmp, for | |||
6589 | // example. | |||
6590 | if (RHSOp0->getType()->isVectorTy() != LHS->getType()->isVectorTy()) | |||
6591 | return None; | |||
6592 | ||||
6593 | Type *OpTy = LHS->getType(); | |||
6594 | assert(OpTy->isIntOrIntVectorTy(1) && "Expected integer type only!")(static_cast <bool> (OpTy->isIntOrIntVectorTy(1) && "Expected integer type only!") ? void (0) : __assert_fail ("OpTy->isIntOrIntVectorTy(1) && \"Expected integer type only!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6594, __extension__ __PRETTY_FUNCTION__)); | |||
6595 | ||||
6596 | // FIXME: Extending the code below to handle vectors. | |||
6597 | if (OpTy->isVectorTy()) | |||
6598 | return None; | |||
6599 | ||||
6600 | assert(OpTy->isIntegerTy(1) && "implied by above")(static_cast <bool> (OpTy->isIntegerTy(1) && "implied by above") ? void (0) : __assert_fail ("OpTy->isIntegerTy(1) && \"implied by above\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6600, __extension__ __PRETTY_FUNCTION__)); | |||
6601 | ||||
6602 | // Both LHS and RHS are icmps. | |||
6603 | const ICmpInst *LHSCmp = dyn_cast<ICmpInst>(LHS); | |||
6604 | if (LHSCmp) | |||
6605 | return isImpliedCondICmps(LHSCmp, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, | |||
6606 | Depth); | |||
6607 | ||||
6608 | /// The LHS should be an 'or', 'and', or a 'select' instruction. We expect | |||
6609 | /// the RHS to be an icmp. | |||
6610 | /// FIXME: Add support for and/or/select on the RHS. | |||
6611 | if (const Instruction *LHSI = dyn_cast<Instruction>(LHS)) { | |||
6612 | if ((LHSI->getOpcode() == Instruction::And || | |||
6613 | LHSI->getOpcode() == Instruction::Or || | |||
6614 | LHSI->getOpcode() == Instruction::Select)) | |||
6615 | return isImpliedCondAndOr(LHSI, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, | |||
6616 | Depth); | |||
6617 | } | |||
6618 | return None; | |||
6619 | } | |||
6620 | ||||
6621 | Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS, | |||
6622 | const DataLayout &DL, bool LHSIsTrue, | |||
6623 | unsigned Depth) { | |||
6624 | // LHS ==> RHS by definition | |||
6625 | if (LHS == RHS) | |||
6626 | return LHSIsTrue; | |||
6627 | ||||
6628 | const ICmpInst *RHSCmp = dyn_cast<ICmpInst>(RHS); | |||
6629 | if (RHSCmp) | |||
6630 | return isImpliedCondition(LHS, RHSCmp->getPredicate(), | |||
6631 | RHSCmp->getOperand(0), RHSCmp->getOperand(1), DL, | |||
6632 | LHSIsTrue, Depth); | |||
6633 | return None; | |||
6634 | } | |||
6635 | ||||
6636 | // Returns a pair (Condition, ConditionIsTrue), where Condition is a branch | |||
6637 | // condition dominating ContextI or nullptr, if no condition is found. | |||
6638 | static std::pair<Value *, bool> | |||
6639 | getDomPredecessorCondition(const Instruction *ContextI) { | |||
6640 | if (!ContextI || !ContextI->getParent()) | |||
6641 | return {nullptr, false}; | |||
6642 | ||||
6643 | // TODO: This is a poor/cheap way to determine dominance. Should we use a | |||
6644 | // dominator tree (eg, from a SimplifyQuery) instead? | |||
6645 | const BasicBlock *ContextBB = ContextI->getParent(); | |||
6646 | const BasicBlock *PredBB = ContextBB->getSinglePredecessor(); | |||
6647 | if (!PredBB) | |||
6648 | return {nullptr, false}; | |||
6649 | ||||
6650 | // We need a conditional branch in the predecessor. | |||
6651 | Value *PredCond; | |||
6652 | BasicBlock *TrueBB, *FalseBB; | |||
6653 | if (!match(PredBB->getTerminator(), m_Br(m_Value(PredCond), TrueBB, FalseBB))) | |||
6654 | return {nullptr, false}; | |||
6655 | ||||
6656 | // The branch should get simplified. Don't bother simplifying this condition. | |||
6657 | if (TrueBB == FalseBB) | |||
6658 | return {nullptr, false}; | |||
6659 | ||||
6660 | 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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6661, __extension__ __PRETTY_FUNCTION__)) | |||
6661 | "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?\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6661, __extension__ __PRETTY_FUNCTION__)); | |||
6662 | ||||
6663 | // Is this condition implied by the predecessor condition? | |||
6664 | return {PredCond, TrueBB == ContextBB}; | |||
6665 | } | |||
6666 | ||||
6667 | Optional<bool> llvm::isImpliedByDomCondition(const Value *Cond, | |||
6668 | const Instruction *ContextI, | |||
6669 | const DataLayout &DL) { | |||
6670 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6670, __extension__ __PRETTY_FUNCTION__)); | |||
6671 | auto PredCond = getDomPredecessorCondition(ContextI); | |||
6672 | if (PredCond.first) | |||
6673 | return isImpliedCondition(PredCond.first, Cond, DL, PredCond.second); | |||
6674 | return None; | |||
6675 | } | |||
6676 | ||||
6677 | Optional<bool> llvm::isImpliedByDomCondition(CmpInst::Predicate Pred, | |||
6678 | const Value *LHS, const Value *RHS, | |||
6679 | const Instruction *ContextI, | |||
6680 | const DataLayout &DL) { | |||
6681 | auto PredCond = getDomPredecessorCondition(ContextI); | |||
6682 | if (PredCond.first) | |||
6683 | return isImpliedCondition(PredCond.first, Pred, LHS, RHS, DL, | |||
6684 | PredCond.second); | |||
6685 | return None; | |||
6686 | } | |||
6687 | ||||
6688 | static void setLimitsForBinOp(const BinaryOperator &BO, APInt &Lower, | |||
6689 | APInt &Upper, const InstrInfoQuery &IIQ) { | |||
6690 | unsigned Width = Lower.getBitWidth(); | |||
6691 | const APInt *C; | |||
6692 | switch (BO.getOpcode()) { | |||
6693 | case Instruction::Add: | |||
6694 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) { | |||
6695 | // FIXME: If we have both nuw and nsw, we should reduce the range further. | |||
6696 | if (IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(&BO))) { | |||
6697 | // 'add nuw x, C' produces [C, UINT_MAX]. | |||
6698 | Lower = *C; | |||
6699 | } else if (IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(&BO))) { | |||
6700 | if (C->isNegative()) { | |||
6701 | // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C]. | |||
6702 | Lower = APInt::getSignedMinValue(Width); | |||
6703 | Upper = APInt::getSignedMaxValue(Width) + *C + 1; | |||
6704 | } else { | |||
6705 | // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX]. | |||
6706 | Lower = APInt::getSignedMinValue(Width) + *C; | |||
6707 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
6708 | } | |||
6709 | } | |||
6710 | } | |||
6711 | break; | |||
6712 | ||||
6713 | case Instruction::And: | |||
6714 | if (match(BO.getOperand(1), m_APInt(C))) | |||
6715 | // 'and x, C' produces [0, C]. | |||
6716 | Upper = *C + 1; | |||
6717 | break; | |||
6718 | ||||
6719 | case Instruction::Or: | |||
6720 | if (match(BO.getOperand(1), m_APInt(C))) | |||
6721 | // 'or x, C' produces [C, UINT_MAX]. | |||
6722 | Lower = *C; | |||
6723 | break; | |||
6724 | ||||
6725 | case Instruction::AShr: | |||
6726 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { | |||
6727 | // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C]. | |||
6728 | Lower = APInt::getSignedMinValue(Width).ashr(*C); | |||
6729 | Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1; | |||
6730 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
6731 | unsigned ShiftAmount = Width - 1; | |||
6732 | if (!C->isNullValue() && IIQ.isExact(&BO)) | |||
6733 | ShiftAmount = C->countTrailingZeros(); | |||
6734 | if (C->isNegative()) { | |||
6735 | // 'ashr C, x' produces [C, C >> (Width-1)] | |||
6736 | Lower = *C; | |||
6737 | Upper = C->ashr(ShiftAmount) + 1; | |||
6738 | } else { | |||
6739 | // 'ashr C, x' produces [C >> (Width-1), C] | |||
6740 | Lower = C->ashr(ShiftAmount); | |||
6741 | Upper = *C + 1; | |||
6742 | } | |||
6743 | } | |||
6744 | break; | |||
6745 | ||||
6746 | case Instruction::LShr: | |||
6747 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { | |||
6748 | // 'lshr x, C' produces [0, UINT_MAX >> C]. | |||
6749 | Upper = APInt::getAllOnesValue(Width).lshr(*C) + 1; | |||
6750 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
6751 | // 'lshr C, x' produces [C >> (Width-1), C]. | |||
6752 | unsigned ShiftAmount = Width - 1; | |||
6753 | if (!C->isNullValue() && IIQ.isExact(&BO)) | |||
6754 | ShiftAmount = C->countTrailingZeros(); | |||
6755 | Lower = C->lshr(ShiftAmount); | |||
6756 | Upper = *C + 1; | |||
6757 | } | |||
6758 | break; | |||
6759 | ||||
6760 | case Instruction::Shl: | |||
6761 | if (match(BO.getOperand(0), m_APInt(C))) { | |||
6762 | if (IIQ.hasNoUnsignedWrap(&BO)) { | |||
6763 | // 'shl nuw C, x' produces [C, C << CLZ(C)] | |||
6764 | Lower = *C; | |||
6765 | Upper = Lower.shl(Lower.countLeadingZeros()) + 1; | |||
6766 | } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw? | |||
6767 | if (C->isNegative()) { | |||
6768 | // 'shl nsw C, x' produces [C << CLO(C)-1, C] | |||
6769 | unsigned ShiftAmount = C->countLeadingOnes() - 1; | |||
6770 | Lower = C->shl(ShiftAmount); | |||
6771 | Upper = *C + 1; | |||
6772 | } else { | |||
6773 | // 'shl nsw C, x' produces [C, C << CLZ(C)-1] | |||
6774 | unsigned ShiftAmount = C->countLeadingZeros() - 1; | |||
6775 | Lower = *C; | |||
6776 | Upper = C->shl(ShiftAmount) + 1; | |||
6777 | } | |||
6778 | } | |||
6779 | } | |||
6780 | break; | |||
6781 | ||||
6782 | case Instruction::SDiv: | |||
6783 | if (match(BO.getOperand(1), m_APInt(C))) { | |||
6784 | APInt IntMin = APInt::getSignedMinValue(Width); | |||
6785 | APInt IntMax = APInt::getSignedMaxValue(Width); | |||
6786 | if (C->isAllOnesValue()) { | |||
6787 | // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX] | |||
6788 | // where C != -1 and C != 0 and C != 1 | |||
6789 | Lower = IntMin + 1; | |||
6790 | Upper = IntMax + 1; | |||
6791 | } else if (C->countLeadingZeros() < Width - 1) { | |||
6792 | // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C] | |||
6793 | // where C != -1 and C != 0 and C != 1 | |||
6794 | Lower = IntMin.sdiv(*C); | |||
6795 | Upper = IntMax.sdiv(*C); | |||
6796 | if (Lower.sgt(Upper)) | |||
6797 | std::swap(Lower, Upper); | |||
6798 | Upper = Upper + 1; | |||
6799 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6799, __extension__ __PRETTY_FUNCTION__)); | |||
6800 | } | |||
6801 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
6802 | if (C->isMinSignedValue()) { | |||
6803 | // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2]. | |||
6804 | Lower = *C; | |||
6805 | Upper = Lower.lshr(1) + 1; | |||
6806 | } else { | |||
6807 | // 'sdiv C, x' produces [-|C|, |C|]. | |||
6808 | Upper = C->abs() + 1; | |||
6809 | Lower = (-Upper) + 1; | |||
6810 | } | |||
6811 | } | |||
6812 | break; | |||
6813 | ||||
6814 | case Instruction::UDiv: | |||
6815 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) { | |||
6816 | // 'udiv x, C' produces [0, UINT_MAX / C]. | |||
6817 | Upper = APInt::getMaxValue(Width).udiv(*C) + 1; | |||
6818 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
6819 | // 'udiv C, x' produces [0, C]. | |||
6820 | Upper = *C + 1; | |||
6821 | } | |||
6822 | break; | |||
6823 | ||||
6824 | case Instruction::SRem: | |||
6825 | if (match(BO.getOperand(1), m_APInt(C))) { | |||
6826 | // 'srem x, C' produces (-|C|, |C|). | |||
6827 | Upper = C->abs(); | |||
6828 | Lower = (-Upper) + 1; | |||
6829 | } | |||
6830 | break; | |||
6831 | ||||
6832 | case Instruction::URem: | |||
6833 | if (match(BO.getOperand(1), m_APInt(C))) | |||
6834 | // 'urem x, C' produces [0, C). | |||
6835 | Upper = *C; | |||
6836 | break; | |||
6837 | ||||
6838 | default: | |||
6839 | break; | |||
6840 | } | |||
6841 | } | |||
6842 | ||||
6843 | static void setLimitsForIntrinsic(const IntrinsicInst &II, APInt &Lower, | |||
6844 | APInt &Upper) { | |||
6845 | unsigned Width = Lower.getBitWidth(); | |||
6846 | const APInt *C; | |||
6847 | switch (II.getIntrinsicID()) { | |||
6848 | case Intrinsic::ctpop: | |||
6849 | case Intrinsic::ctlz: | |||
6850 | case Intrinsic::cttz: | |||
6851 | // Maximum of set/clear bits is the bit width. | |||
6852 | assert(Lower == 0 && "Expected lower bound to be zero")(static_cast <bool> (Lower == 0 && "Expected lower bound to be zero" ) ? void (0) : __assert_fail ("Lower == 0 && \"Expected lower bound to be zero\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6852, __extension__ __PRETTY_FUNCTION__)); | |||
6853 | Upper = Width + 1; | |||
6854 | break; | |||
6855 | case Intrinsic::uadd_sat: | |||
6856 | // uadd.sat(x, C) produces [C, UINT_MAX]. | |||
6857 | if (match(II.getOperand(0), m_APInt(C)) || | |||
6858 | match(II.getOperand(1), m_APInt(C))) | |||
6859 | Lower = *C; | |||
6860 | break; | |||
6861 | case Intrinsic::sadd_sat: | |||
6862 | if (match(II.getOperand(0), m_APInt(C)) || | |||
6863 | match(II.getOperand(1), m_APInt(C))) { | |||
6864 | if (C->isNegative()) { | |||
6865 | // sadd.sat(x, -C) produces [SINT_MIN, SINT_MAX + (-C)]. | |||
6866 | Lower = APInt::getSignedMinValue(Width); | |||
6867 | Upper = APInt::getSignedMaxValue(Width) + *C + 1; | |||
6868 | } else { | |||
6869 | // sadd.sat(x, +C) produces [SINT_MIN + C, SINT_MAX]. | |||
6870 | Lower = APInt::getSignedMinValue(Width) + *C; | |||
6871 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
6872 | } | |||
6873 | } | |||
6874 | break; | |||
6875 | case Intrinsic::usub_sat: | |||
6876 | // usub.sat(C, x) produces [0, C]. | |||
6877 | if (match(II.getOperand(0), m_APInt(C))) | |||
6878 | Upper = *C + 1; | |||
6879 | // usub.sat(x, C) produces [0, UINT_MAX - C]. | |||
6880 | else if (match(II.getOperand(1), m_APInt(C))) | |||
6881 | Upper = APInt::getMaxValue(Width) - *C + 1; | |||
6882 | break; | |||
6883 | case Intrinsic::ssub_sat: | |||
6884 | if (match(II.getOperand(0), m_APInt(C))) { | |||
6885 | if (C->isNegative()) { | |||
6886 | // ssub.sat(-C, x) produces [SINT_MIN, -SINT_MIN + (-C)]. | |||
6887 | Lower = APInt::getSignedMinValue(Width); | |||
6888 | Upper = *C - APInt::getSignedMinValue(Width) + 1; | |||
6889 | } else { | |||
6890 | // ssub.sat(+C, x) produces [-SINT_MAX + C, SINT_MAX]. | |||
6891 | Lower = *C - APInt::getSignedMaxValue(Width); | |||
6892 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
6893 | } | |||
6894 | } else if (match(II.getOperand(1), m_APInt(C))) { | |||
6895 | if (C->isNegative()) { | |||
6896 | // ssub.sat(x, -C) produces [SINT_MIN - (-C), SINT_MAX]: | |||
6897 | Lower = APInt::getSignedMinValue(Width) - *C; | |||
6898 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
6899 | } else { | |||
6900 | // ssub.sat(x, +C) produces [SINT_MIN, SINT_MAX - C]. | |||
6901 | Lower = APInt::getSignedMinValue(Width); | |||
6902 | Upper = APInt::getSignedMaxValue(Width) - *C + 1; | |||
6903 | } | |||
6904 | } | |||
6905 | break; | |||
6906 | case Intrinsic::umin: | |||
6907 | case Intrinsic::umax: | |||
6908 | case Intrinsic::smin: | |||
6909 | case Intrinsic::smax: | |||
6910 | if (!match(II.getOperand(0), m_APInt(C)) && | |||
6911 | !match(II.getOperand(1), m_APInt(C))) | |||
6912 | break; | |||
6913 | ||||
6914 | switch (II.getIntrinsicID()) { | |||
6915 | case Intrinsic::umin: | |||
6916 | Upper = *C + 1; | |||
6917 | break; | |||
6918 | case Intrinsic::umax: | |||
6919 | Lower = *C; | |||
6920 | break; | |||
6921 | case Intrinsic::smin: | |||
6922 | Lower = APInt::getSignedMinValue(Width); | |||
6923 | Upper = *C + 1; | |||
6924 | break; | |||
6925 | case Intrinsic::smax: | |||
6926 | Lower = *C; | |||
6927 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
6928 | break; | |||
6929 | default: | |||
6930 | llvm_unreachable("Must be min/max intrinsic")::llvm::llvm_unreachable_internal("Must be min/max intrinsic" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 6930); | |||
6931 | } | |||
6932 | break; | |||
6933 | case Intrinsic::abs: | |||
6934 | // If abs of SIGNED_MIN is poison, then the result is [0..SIGNED_MAX], | |||
6935 | // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN. | |||
6936 | if (match(II.getOperand(1), m_One())) | |||
6937 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
6938 | else | |||
6939 | Upper = APInt::getSignedMinValue(Width) + 1; | |||
6940 | break; | |||
6941 | default: | |||
6942 | break; | |||
6943 | } | |||
6944 | } | |||
6945 | ||||
6946 | static void setLimitsForSelectPattern(const SelectInst &SI, APInt &Lower, | |||
6947 | APInt &Upper, const InstrInfoQuery &IIQ) { | |||
6948 | const Value *LHS = nullptr, *RHS = nullptr; | |||
6949 | SelectPatternResult R = matchSelectPattern(&SI, LHS, RHS); | |||
6950 | if (R.Flavor == SPF_UNKNOWN) | |||
6951 | return; | |||
6952 | ||||
6953 | unsigned BitWidth = SI.getType()->getScalarSizeInBits(); | |||
6954 | ||||
6955 | if (R.Flavor == SelectPatternFlavor::SPF_ABS) { | |||
6956 | // If the negation part of the abs (in RHS) has the NSW flag, | |||
6957 | // then the result of abs(X) is [0..SIGNED_MAX], | |||
6958 | // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN. | |||
6959 | Lower = APInt::getNullValue(BitWidth); | |||
6960 | if (match(RHS, m_Neg(m_Specific(LHS))) && | |||
6961 | IIQ.hasNoSignedWrap(cast<Instruction>(RHS))) | |||
6962 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; | |||
6963 | else | |||
6964 | Upper = APInt::getSignedMinValue(BitWidth) + 1; | |||
6965 | return; | |||
6966 | } | |||
6967 | ||||
6968 | if (R.Flavor == SelectPatternFlavor::SPF_NABS) { | |||
6969 | // The result of -abs(X) is <= 0. | |||
6970 | Lower = APInt::getSignedMinValue(BitWidth); | |||
6971 | Upper = APInt(BitWidth, 1); | |||
6972 | return; | |||
6973 | } | |||
6974 | ||||
6975 | const APInt *C; | |||
6976 | if (!match(LHS, m_APInt(C)) && !match(RHS, m_APInt(C))) | |||
6977 | return; | |||
6978 | ||||
6979 | switch (R.Flavor) { | |||
6980 | case SPF_UMIN: | |||
6981 | Upper = *C + 1; | |||
6982 | break; | |||
6983 | case SPF_UMAX: | |||
6984 | Lower = *C; | |||
6985 | break; | |||
6986 | case SPF_SMIN: | |||
6987 | Lower = APInt::getSignedMinValue(BitWidth); | |||
6988 | Upper = *C + 1; | |||
6989 | break; | |||
6990 | case SPF_SMAX: | |||
6991 | Lower = *C; | |||
6992 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; | |||
6993 | break; | |||
6994 | default: | |||
6995 | break; | |||
6996 | } | |||
6997 | } | |||
6998 | ||||
6999 | ConstantRange llvm::computeConstantRange(const Value *V, bool UseInstrInfo, | |||
7000 | AssumptionCache *AC, | |||
7001 | const Instruction *CtxI, | |||
7002 | unsigned Depth) { | |||
7003 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 7003, __extension__ __PRETTY_FUNCTION__)); | |||
7004 | ||||
7005 | if (Depth == MaxAnalysisRecursionDepth) | |||
7006 | return ConstantRange::getFull(V->getType()->getScalarSizeInBits()); | |||
7007 | ||||
7008 | const APInt *C; | |||
7009 | if (match(V, m_APInt(C))) | |||
7010 | return ConstantRange(*C); | |||
7011 | ||||
7012 | InstrInfoQuery IIQ(UseInstrInfo); | |||
7013 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); | |||
7014 | APInt Lower = APInt(BitWidth, 0); | |||
7015 | APInt Upper = APInt(BitWidth, 0); | |||
7016 | if (auto *BO = dyn_cast<BinaryOperator>(V)) | |||
7017 | setLimitsForBinOp(*BO, Lower, Upper, IIQ); | |||
7018 | else if (auto *II = dyn_cast<IntrinsicInst>(V)) | |||
7019 | setLimitsForIntrinsic(*II, Lower, Upper); | |||
7020 | else if (auto *SI = dyn_cast<SelectInst>(V)) | |||
7021 | setLimitsForSelectPattern(*SI, Lower, Upper, IIQ); | |||
7022 | ||||
7023 | ConstantRange CR = ConstantRange::getNonEmpty(Lower, Upper); | |||
7024 | ||||
7025 | if (auto *I = dyn_cast<Instruction>(V)) | |||
7026 | if (auto *Range = IIQ.getMetadata(I, LLVMContext::MD_range)) | |||
7027 | CR = CR.intersectWith(getConstantRangeFromMetadata(*Range)); | |||
7028 | ||||
7029 | if (CtxI && AC) { | |||
7030 | // Try to restrict the range based on information from assumptions. | |||
7031 | for (auto &AssumeVH : AC->assumptionsFor(V)) { | |||
7032 | if (!AssumeVH) | |||
7033 | continue; | |||
7034 | CallInst *I = cast<CallInst>(AssumeVH); | |||
7035 | 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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 7036, __extension__ __PRETTY_FUNCTION__)) | |||
7036 | "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!\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 7036, __extension__ __PRETTY_FUNCTION__)); | |||
7037 | 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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 7038, __extension__ __PRETTY_FUNCTION__)) | |||
7038 | "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\"" , "/build/llvm-toolchain-snapshot-14~++20210828111110+16086d47c0d0/llvm/lib/Analysis/ValueTracking.cpp" , 7038, __extension__ __PRETTY_FUNCTION__)); | |||
7039 | ||||
7040 | if (!isValidAssumeForContext(I, CtxI, nullptr)) | |||
7041 | continue; | |||
7042 | Value *Arg = I->getArgOperand(0); | |||
7043 | ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg); | |||
7044 | // Currently we just use information from comparisons. | |||
7045 | if (!Cmp || Cmp->getOperand(0) != V) | |||
7046 | continue; | |||
7047 | ConstantRange RHS = computeConstantRange(Cmp->getOperand(1), UseInstrInfo, | |||
7048 | AC, I, Depth + 1); | |||
7049 | CR = CR.intersectWith( | |||
7050 | ConstantRange::makeAllowedICmpRegion(Cmp->getPredicate(), RHS)); | |||
7051 | } | |||
7052 | } | |||
7053 | ||||
7054 | return CR; | |||
7055 | } | |||
7056 | ||||
7057 | static Optional<int64_t> | |||
7058 | getOffsetFromIndex(const GEPOperator *GEP, unsigned Idx, const DataLayout &DL) { | |||
7059 | // Skip over the first indices. | |||
7060 | gep_type_iterator GTI = gep_type_begin(GEP); | |||
7061 | for (unsigned i = 1; i != Idx; ++i, ++GTI) | |||
7062 | /*skip along*/; | |||
7063 | ||||
7064 | // Compute the offset implied by the rest of the indices. | |||
7065 | int64_t Offset = 0; | |||
7066 | for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { | |||
7067 | ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i)); | |||
7068 | if (!OpC) | |||
7069 | return None; | |||
7070 | if (OpC->isZero()) | |||
7071 | continue; // No offset. | |||
7072 | ||||
7073 | // Handle struct indices, which add their field offset to the pointer. | |||
7074 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
7075 | Offset += DL.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); | |||
7076 | continue; | |||
7077 | } | |||
7078 | ||||
7079 | // Otherwise, we have a sequential type like an array or fixed-length | |||
7080 | // vector. Multiply the index by the ElementSize. | |||
7081 | TypeSize Size = DL.getTypeAllocSize(GTI.getIndexedType()); | |||
7082 | if (Size.isScalable()) | |||
7083 | return None; | |||
7084 | Offset += Size.getFixedSize() * OpC->getSExtValue(); | |||
7085 | } | |||
7086 | ||||
7087 | return Offset; | |||
7088 | } | |||
7089 | ||||
7090 | Optional<int64_t> llvm::isPointerOffset(const Value *Ptr1, const Value *Ptr2, | |||
7091 | const DataLayout &DL) { | |||
7092 | Ptr1 = Ptr1->stripPointerCasts(); | |||
7093 | Ptr2 = Ptr2->stripPointerCasts(); | |||
7094 | ||||
7095 | // Handle the trivial case first. | |||
7096 | if (Ptr1 == Ptr2) { | |||
7097 | return 0; | |||
7098 | } | |||
7099 | ||||
7100 | const GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1); | |||
7101 | const GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2); | |||
7102 | ||||
7103 | // If one pointer is a GEP see if the GEP is a constant offset from the base, | |||
7104 | // as in "P" and "gep P, 1". | |||
7105 | // Also do this iteratively to handle the the following case: | |||
7106 | // Ptr_t1 = GEP Ptr1, c1 | |||
7107 | // Ptr_t2 = GEP Ptr_t1, c2 | |||
7108 | // Ptr2 = GEP Ptr_t2, c3 | |||
7109 | // where we will return c1+c2+c3. | |||
7110 | // TODO: Handle the case when both Ptr1 and Ptr2 are GEPs of some common base | |||
7111 | // -- replace getOffsetFromBase with getOffsetAndBase, check that the bases | |||
7112 | // are the same, and return the difference between offsets. | |||
7113 | auto getOffsetFromBase = [&DL](const GEPOperator *GEP, | |||
7114 | const Value *Ptr) -> Optional<int64_t> { | |||
7115 | const GEPOperator *GEP_T = GEP; | |||
7116 | int64_t OffsetVal = 0; | |||
7117 | bool HasSameBase = false; | |||
7118 | while (GEP_T) { | |||
7119 | auto Offset = getOffsetFromIndex(GEP_T, 1, DL); | |||
7120 | if (!Offset) | |||
7121 | return None; | |||
7122 | OffsetVal += *Offset; | |||
7123 | auto Op0 = GEP_T->getOperand(0)->stripPointerCasts(); | |||
7124 | if (Op0 == Ptr) { | |||
7125 | HasSameBase = true; | |||
7126 | break; | |||
7127 | } | |||
7128 | GEP_T = dyn_cast<GEPOperator>(Op0); | |||
7129 | } | |||
7130 | if (!HasSameBase) | |||
7131 | return None; | |||
7132 | return OffsetVal; | |||
7133 | }; | |||
7134 | ||||
7135 | if (GEP1) { | |||
7136 | auto Offset = getOffsetFromBase(GEP1, Ptr2); | |||
7137 | if (Offset) | |||
7138 | return -*Offset; | |||
7139 | } | |||
7140 | if (GEP2) { | |||
7141 | auto Offset = getOffsetFromBase(GEP2, Ptr1); | |||
7142 | if (Offset) | |||
7143 | return Offset; | |||
7144 | } | |||
7145 | ||||
7146 | // Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical | |||
7147 | // base. After that base, they may have some number of common (and | |||
7148 | // potentially variable) indices. After that they handle some constant | |||
7149 | // offset, which determines their offset from each other. At this point, we | |||
7150 | // handle no other case. | |||
7151 | if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0)) | |||
7152 | return None; | |||
7153 | ||||
7154 | // Skip any common indices and track the GEP types. | |||
7155 | unsigned Idx = 1; | |||
7156 | for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx) | |||
7157 | if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx)) | |||
7158 | break; | |||
7159 | ||||
7160 | auto Offset1 = getOffsetFromIndex(GEP1, Idx, DL); | |||
7161 | auto Offset2 = getOffsetFromIndex(GEP2, Idx, DL); | |||
7162 | if (!Offset1 || !Offset2) | |||
7163 | return None; | |||
7164 | return *Offset2 - *Offset1; | |||
7165 | } |
1 | //===-- llvm/Operator.h - Operator utility subclass -------------*- C++ -*-===// | ||||
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 defines various classes for working with Instructions and | ||||
10 | // ConstantExprs. | ||||
11 | // | ||||
12 | //===----------------------------------------------------------------------===// | ||||
13 | |||||
14 | #ifndef LLVM_IR_OPERATOR_H | ||||
15 | #define LLVM_IR_OPERATOR_H | ||||
16 | |||||
17 | #include "llvm/ADT/MapVector.h" | ||||
18 | #include "llvm/ADT/None.h" | ||||
19 | #include "llvm/ADT/Optional.h" | ||||
20 | #include "llvm/IR/Constants.h" | ||||
21 | #include "llvm/IR/Instruction.h" | ||||
22 | #include "llvm/IR/Type.h" | ||||
23 | #include "llvm/IR/Value.h" | ||||
24 | #include "llvm/Support/Casting.h" | ||||
25 | #include <cstddef> | ||||
26 | |||||
27 | namespace llvm { | ||||
28 | |||||
29 | /// This is a utility class that provides an abstraction for the common | ||||
30 | /// functionality between Instructions and ConstantExprs. | ||||
31 | class Operator : public User { | ||||
32 | public: | ||||
33 | // The Operator class is intended to be used as a utility, and is never itself | ||||
34 | // instantiated. | ||||
35 | Operator() = delete; | ||||
36 | ~Operator() = delete; | ||||
37 | |||||
38 | void *operator new(size_t s) = delete; | ||||
39 | |||||
40 | /// Return the opcode for this Instruction or ConstantExpr. | ||||
41 | unsigned getOpcode() const { | ||||
42 | if (const Instruction *I
| ||||
43 | return I->getOpcode(); | ||||
44 | return cast<ConstantExpr>(this)->getOpcode(); | ||||
45 | } | ||||
46 | |||||
47 | /// If V is an Instruction or ConstantExpr, return its opcode. | ||||
48 | /// Otherwise return UserOp1. | ||||
49 | static unsigned getOpcode(const Value *V) { | ||||
50 | if (const Instruction *I = dyn_cast<Instruction>(V)) | ||||
51 | return I->getOpcode(); | ||||
52 | if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) | ||||
53 | return CE->getOpcode(); | ||||
54 | return Instruction::UserOp1; | ||||
55 | } | ||||
56 | |||||
57 | static bool classof(const Instruction *) { return true; } | ||||
58 | static bool classof(const ConstantExpr *) { return true; } | ||||
59 | static bool classof(const Value *V) { | ||||
60 | return isa<Instruction>(V) || isa<ConstantExpr>(V); | ||||
61 | } | ||||
62 | }; | ||||
63 | |||||
64 | /// Utility class for integer operators which may exhibit overflow - Add, Sub, | ||||
65 | /// Mul, and Shl. It does not include SDiv, despite that operator having the | ||||
66 | /// potential for overflow. | ||||
67 | class OverflowingBinaryOperator : public Operator { | ||||
68 | public: | ||||
69 | enum { | ||||
70 | AnyWrap = 0, | ||||
71 | NoUnsignedWrap = (1 << 0), | ||||
72 | NoSignedWrap = (1 << 1) | ||||
73 | }; | ||||
74 | |||||
75 | private: | ||||
76 | friend class Instruction; | ||||
77 | friend class ConstantExpr; | ||||
78 | |||||
79 | void setHasNoUnsignedWrap(bool B) { | ||||
80 | SubclassOptionalData = | ||||
81 | (SubclassOptionalData & ~NoUnsignedWrap) | (B * NoUnsignedWrap); | ||||
82 | } | ||||
83 | void setHasNoSignedWrap(bool B) { | ||||
84 | SubclassOptionalData = | ||||
85 | (SubclassOptionalData & ~NoSignedWrap) | (B * NoSignedWrap); | ||||
86 | } | ||||
87 | |||||
88 | public: | ||||
89 | /// Test whether this operation is known to never | ||||
90 | /// undergo unsigned overflow, aka the nuw property. | ||||
91 | bool hasNoUnsignedWrap() const { | ||||
92 | return SubclassOptionalData & NoUnsignedWrap; | ||||
93 | } | ||||
94 | |||||
95 | /// Test whether this operation is known to never | ||||
96 | /// undergo signed overflow, aka the nsw property. | ||||
97 | bool hasNoSignedWrap() const { | ||||
98 | return (SubclassOptionalData & NoSignedWrap) != 0; | ||||
99 | } | ||||
100 | |||||
101 | static bool classof(const Instruction *I) { | ||||
102 | return I->getOpcode() == Instruction::Add || | ||||
103 | I->getOpcode() == Instruction::Sub || | ||||
104 | I->getOpcode() == Instruction::Mul || | ||||
105 | I->getOpcode() == Instruction::Shl; | ||||
106 | } | ||||
107 | static bool classof(const ConstantExpr *CE) { | ||||
108 | return CE->getOpcode() == Instruction::Add || | ||||
109 | CE->getOpcode() == Instruction::Sub || | ||||
110 | CE->getOpcode() == Instruction::Mul || | ||||
111 | CE->getOpcode() == Instruction::Shl; | ||||
112 | } | ||||
113 | static bool classof(const Value *V) { | ||||
114 | return (isa<Instruction>(V) && classof(cast<Instruction>(V))) || | ||||
115 | (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V))); | ||||
116 | } | ||||
117 | }; | ||||
118 | |||||
119 | /// A udiv or sdiv instruction, which can be marked as "exact", | ||||
120 | /// indicating that no bits are destroyed. | ||||
121 | class PossiblyExactOperator : public Operator { | ||||
122 | public: | ||||
123 | enum { | ||||
124 | IsExact = (1 << 0) | ||||
125 | }; | ||||
126 | |||||
127 | private: | ||||
128 | friend class Instruction; | ||||
129 | friend class ConstantExpr; | ||||
130 | |||||
131 | void setIsExact(bool B) { | ||||
132 | SubclassOptionalData = (SubclassOptionalData & ~IsExact) | (B * IsExact); | ||||
133 | } | ||||
134 | |||||
135 | public: | ||||
136 | /// Test whether this division is known to be exact, with zero remainder. | ||||
137 | bool isExact() const { | ||||
138 | return SubclassOptionalData & IsExact; | ||||
139 | } | ||||
140 | |||||
141 | static bool isPossiblyExactOpcode(unsigned OpC) { | ||||
142 | return OpC == Instruction::SDiv || | ||||
143 | OpC == Instruction::UDiv || | ||||
144 | OpC == Instruction::AShr || | ||||
145 | OpC == Instruction::LShr; | ||||
146 | } | ||||
147 | |||||
148 | static bool classof(const ConstantExpr *CE) { | ||||
149 | return isPossiblyExactOpcode(CE->getOpcode()); | ||||
150 | } | ||||
151 | static bool classof(const Instruction *I) { | ||||
152 | return isPossiblyExactOpcode(I->getOpcode()); | ||||
153 | } | ||||
154 | static bool classof(const Value *V) { | ||||
155 | return (isa<Instruction>(V) && classof(cast<Instruction>(V))) || | ||||
156 | (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V))); | ||||
157 | } | ||||
158 | }; | ||||
159 | |||||
160 | /// Convenience struct for specifying and reasoning about fast-math flags. | ||||
161 | class FastMathFlags { | ||||
162 | private: | ||||
163 | friend class FPMathOperator; | ||||
164 | |||||
165 | unsigned Flags = 0; | ||||
166 | |||||
167 | FastMathFlags(unsigned F) { | ||||
168 | // If all 7 bits are set, turn this into -1. If the number of bits grows, | ||||
169 | // this must be updated. This is intended to provide some forward binary | ||||
170 | // compatibility insurance for the meaning of 'fast' in case bits are added. | ||||
171 | if (F == 0x7F) Flags = ~0U; | ||||
172 | else Flags = F; | ||||
173 | } | ||||
174 | |||||
175 | public: | ||||
176 | // This is how the bits are used in Value::SubclassOptionalData so they | ||||
177 | // should fit there too. | ||||
178 | // WARNING: We're out of space. SubclassOptionalData only has 7 bits. New | ||||
179 | // functionality will require a change in how this information is stored. | ||||
180 | enum { | ||||
181 | AllowReassoc = (1 << 0), | ||||
182 | NoNaNs = (1 << 1), | ||||
183 | NoInfs = (1 << 2), | ||||
184 | NoSignedZeros = (1 << 3), | ||||
185 | AllowReciprocal = (1 << 4), | ||||
186 | AllowContract = (1 << 5), | ||||
187 | ApproxFunc = (1 << 6) | ||||
188 | }; | ||||
189 | |||||
190 | FastMathFlags() = default; | ||||
191 | |||||
192 | static FastMathFlags getFast() { | ||||
193 | FastMathFlags FMF; | ||||
194 | FMF.setFast(); | ||||
195 | return FMF; | ||||
196 | } | ||||
197 | |||||
198 | bool any() const { return Flags != 0; } | ||||
199 | bool none() const { return Flags == 0; } | ||||
200 | bool all() const { return Flags == ~0U; } | ||||
201 | |||||
202 | void clear() { Flags = 0; } | ||||
203 | void set() { Flags = ~0U; } | ||||
204 | |||||
205 | /// Flag queries | ||||
206 | bool allowReassoc() const { return 0 != (Flags & AllowReassoc); } | ||||
207 | bool noNaNs() const { return 0 != (Flags & NoNaNs); } | ||||
208 | bool noInfs() const { return 0 != (Flags & NoInfs); } | ||||
209 | bool noSignedZeros() const { return 0 != (Flags & NoSignedZeros); } | ||||
210 | bool allowReciprocal() const { return 0 != (Flags & AllowReciprocal); } | ||||
211 | bool allowContract() const { return 0 != (Flags & AllowContract); } | ||||
212 | bool approxFunc() const { return 0 != (Flags & ApproxFunc); } | ||||
213 | /// 'Fast' means all bits are set. | ||||
214 | bool isFast() const { return all(); } | ||||
215 | |||||
216 | /// Flag setters | ||||
217 | void setAllowReassoc(bool B = true) { | ||||
218 | Flags = (Flags & ~AllowReassoc) | B * AllowReassoc; | ||||
219 | } | ||||
220 | void setNoNaNs(bool B = true) { | ||||
221 | Flags = (Flags & ~NoNaNs) | B * NoNaNs; | ||||
222 | } | ||||
223 | void setNoInfs(bool B = true) { | ||||
224 | Flags = (Flags & ~NoInfs) | B * NoInfs; | ||||
225 | } | ||||
226 | void setNoSignedZeros(bool B = true) { | ||||
227 | Flags = (Flags & ~NoSignedZeros) | B * NoSignedZeros; | ||||
228 | } | ||||
229 | void setAllowReciprocal(bool B = true) { | ||||
230 | Flags = (Flags & ~AllowReciprocal) | B * AllowReciprocal; | ||||
231 | } | ||||
232 | void setAllowContract(bool B = true) { | ||||
233 | Flags = (Flags & ~AllowContract) | B * AllowContract; | ||||
234 | } | ||||
235 | void setApproxFunc(bool B = true) { | ||||
236 | Flags = (Flags & ~ApproxFunc) | B * ApproxFunc; | ||||
237 | } | ||||
238 | void setFast(bool B = true) { B ? set() : clear(); } | ||||
239 | |||||
240 | void operator&=(const FastMathFlags &OtherFlags) { | ||||
241 | Flags &= OtherFlags.Flags; | ||||
242 | } | ||||
243 | void operator|=(const FastMathFlags &OtherFlags) { | ||||
244 | Flags |= OtherFlags.Flags; | ||||
245 | } | ||||
246 | }; | ||||
247 | |||||
248 | /// Utility class for floating point operations which can have | ||||
249 | /// information about relaxed accuracy requirements attached to them. | ||||
250 | class FPMathOperator : public Operator { | ||||
251 | private: | ||||
252 | friend class Instruction; | ||||
253 | |||||
254 | /// 'Fast' means all bits are set. | ||||
255 | void setFast(bool B) { | ||||
256 | setHasAllowReassoc(B); | ||||
257 | setHasNoNaNs(B); | ||||
258 | setHasNoInfs(B); | ||||
259 | setHasNoSignedZeros(B); | ||||
260 | setHasAllowReciprocal(B); | ||||
261 | setHasAllowContract(B); | ||||
262 | setHasApproxFunc(B); | ||||
263 | } | ||||
264 | |||||
265 | void setHasAllowReassoc(bool B) { | ||||
266 | SubclassOptionalData = | ||||
267 | (SubclassOptionalData & ~FastMathFlags::AllowReassoc) | | ||||
268 | (B * FastMathFlags::AllowReassoc); | ||||
269 | } | ||||
270 | |||||
271 | void setHasNoNaNs(bool B) { | ||||
272 | SubclassOptionalData = | ||||
273 | (SubclassOptionalData & ~FastMathFlags::NoNaNs) | | ||||
274 | (B * FastMathFlags::NoNaNs); | ||||
275 | } | ||||
276 | |||||
277 | void setHasNoInfs(bool B) { | ||||
278 | SubclassOptionalData = | ||||
279 | (SubclassOptionalData & ~FastMathFlags::NoInfs) | | ||||
280 | (B * FastMathFlags::NoInfs); | ||||
281 | } | ||||
282 | |||||
283 | void setHasNoSignedZeros(bool B) { | ||||
284 | SubclassOptionalData = | ||||
285 | (SubclassOptionalData & ~FastMathFlags::NoSignedZeros) | | ||||
286 | (B * FastMathFlags::NoSignedZeros); | ||||
287 | } | ||||
288 | |||||
289 | void setHasAllowReciprocal(bool B) { | ||||
290 | SubclassOptionalData = | ||||
291 | (SubclassOptionalData & ~FastMathFlags::AllowReciprocal) | | ||||
292 | (B * FastMathFlags::AllowReciprocal); | ||||
293 | } | ||||
294 | |||||
295 | void setHasAllowContract(bool B) { | ||||
296 | SubclassOptionalData = | ||||
297 | (SubclassOptionalData & ~FastMathFlags::AllowContract) | | ||||
298 | (B * FastMathFlags::AllowContract); | ||||
299 | } | ||||
300 | |||||
301 | void setHasApproxFunc(bool B) { | ||||
302 | SubclassOptionalData = | ||||
303 | (SubclassOptionalData & ~FastMathFlags::ApproxFunc) | | ||||
304 | (B * FastMathFlags::ApproxFunc); | ||||
305 | } | ||||
306 | |||||
307 | /// Convenience function for setting multiple fast-math flags. | ||||
308 | /// FMF is a mask of the bits to set. | ||||
309 | void setFastMathFlags(FastMathFlags FMF) { | ||||
310 | SubclassOptionalData |= FMF.Flags; | ||||
311 | } | ||||
312 | |||||
313 | /// Convenience function for copying all fast-math flags. | ||||
314 | /// All values in FMF are transferred to this operator. | ||||
315 | void copyFastMathFlags(FastMathFlags FMF) { | ||||
316 | SubclassOptionalData = FMF.Flags; | ||||
317 | } | ||||
318 | |||||
319 | public: | ||||
320 | /// Test if this operation allows all non-strict floating-point transforms. | ||||
321 | bool isFast() const { | ||||
322 | return ((SubclassOptionalData & FastMathFlags::AllowReassoc) != 0 && | ||||
323 | (SubclassOptionalData & FastMathFlags::NoNaNs) != 0 && | ||||
324 | (SubclassOptionalData & FastMathFlags::NoInfs) != 0 && | ||||
325 | (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0 && | ||||
326 | (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0 && | ||||
327 | (SubclassOptionalData & FastMathFlags::AllowContract) != 0 && | ||||
328 | (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0); | ||||
329 | } | ||||
330 | |||||
331 | /// Test if this operation may be simplified with reassociative transforms. | ||||
332 | bool hasAllowReassoc() const { | ||||
333 | return (SubclassOptionalData & FastMathFlags::AllowReassoc) != 0; | ||||
334 | } | ||||
335 | |||||
336 | /// Test if this operation's arguments and results are assumed not-NaN. | ||||
337 | bool hasNoNaNs() const { | ||||
338 | return (SubclassOptionalData & FastMathFlags::NoNaNs) != 0; | ||||
339 | } | ||||
340 | |||||
341 | /// Test if this operation's arguments and results are assumed not-infinite. | ||||
342 | bool hasNoInfs() const { | ||||
343 | return (SubclassOptionalData & FastMathFlags::NoInfs) != 0; | ||||
344 | } | ||||
345 | |||||
346 | /// Test if this operation can ignore the sign of zero. | ||||
347 | bool hasNoSignedZeros() const { | ||||
348 | return (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0; | ||||
349 | } | ||||
350 | |||||
351 | /// Test if this operation can use reciprocal multiply instead of division. | ||||
352 | bool hasAllowReciprocal() const { | ||||
353 | return (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0; | ||||
354 | } | ||||
355 | |||||
356 | /// Test if this operation can be floating-point contracted (FMA). | ||||
357 | bool hasAllowContract() const { | ||||
358 | return (SubclassOptionalData & FastMathFlags::AllowContract) != 0; | ||||
359 | } | ||||
360 | |||||
361 | /// Test if this operation allows approximations of math library functions or | ||||
362 | /// intrinsics. | ||||
363 | bool hasApproxFunc() const { | ||||
364 | return (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0; | ||||
365 | } | ||||
366 | |||||
367 | /// Convenience function for getting all the fast-math flags | ||||
368 | FastMathFlags getFastMathFlags() const { | ||||
369 | return FastMathFlags(SubclassOptionalData); | ||||
370 | } | ||||
371 | |||||
372 | /// Get the maximum error permitted by this operation in ULPs. An accuracy of | ||||
373 | /// 0.0 means that the operation should be performed with the default | ||||
374 | /// precision. | ||||
375 | float getFPAccuracy() const; | ||||
376 | |||||
377 | static bool classof(const Value *V) { | ||||
378 | unsigned Opcode; | ||||
379 | if (auto *I = dyn_cast<Instruction>(V)) | ||||
380 | Opcode = I->getOpcode(); | ||||
381 | else if (auto *CE = dyn_cast<ConstantExpr>(V)) | ||||
382 | Opcode = CE->getOpcode(); | ||||
383 | else | ||||
384 | return false; | ||||
385 | |||||
386 | switch (Opcode) { | ||||
387 | case Instruction::FNeg: | ||||
388 | case Instruction::FAdd: | ||||
389 | case Instruction::FSub: | ||||
390 | case Instruction::FMul: | ||||
391 | case Instruction::FDiv: | ||||
392 | case Instruction::FRem: | ||||
393 | // FIXME: To clean up and correct the semantics of fast-math-flags, FCmp | ||||
394 | // should not be treated as a math op, but the other opcodes should. | ||||
395 | // This would make things consistent with Select/PHI (FP value type | ||||
396 | // determines whether they are math ops and, therefore, capable of | ||||
397 | // having fast-math-flags). | ||||
398 | case Instruction::FCmp: | ||||
399 | return true; | ||||
400 | case Instruction::PHI: | ||||
401 | case Instruction::Select: | ||||
402 | case Instruction::Call: { | ||||
403 | Type *Ty = V->getType(); | ||||
404 | while (ArrayType *ArrTy = dyn_cast<ArrayType>(Ty)) | ||||
405 | Ty = ArrTy->getElementType(); | ||||
406 | return Ty->isFPOrFPVectorTy(); | ||||
407 | } | ||||
408 | default: | ||||
409 | return false; | ||||
410 | } | ||||
411 | } | ||||
412 | }; | ||||
413 | |||||
414 | /// A helper template for defining operators for individual opcodes. | ||||
415 | template<typename SuperClass, unsigned Opc> | ||||
416 | class ConcreteOperator : public SuperClass { | ||||
417 | public: | ||||
418 | static bool classof(const Instruction *I) { | ||||
419 | return I->getOpcode() == Opc; | ||||
420 | } | ||||
421 | static bool classof(const ConstantExpr *CE) { | ||||
422 | return CE->getOpcode() == Opc; | ||||
423 | } | ||||
424 | static bool classof(const Value *V) { | ||||
425 | return (isa<Instruction>(V) && classof(cast<Instruction>(V))) || | ||||
426 | (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V))); | ||||
427 | } | ||||
428 | }; | ||||
429 | |||||
430 | class AddOperator | ||||
431 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Add> { | ||||
432 | }; | ||||
433 | class SubOperator | ||||
434 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Sub> { | ||||
435 | }; | ||||
436 | class MulOperator | ||||
437 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Mul> { | ||||
438 | }; | ||||
439 | class ShlOperator | ||||
440 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Shl> { | ||||
441 | }; | ||||
442 | |||||
443 | class SDivOperator | ||||
444 | : public ConcreteOperator<PossiblyExactOperator, Instruction::SDiv> { | ||||
445 | }; | ||||
446 | class UDivOperator | ||||
447 | : public ConcreteOperator<PossiblyExactOperator, Instruction::UDiv> { | ||||
448 | }; | ||||
449 | class AShrOperator | ||||
450 | : public ConcreteOperator<PossiblyExactOperator, Instruction::AShr> { | ||||
451 | }; | ||||
452 | class LShrOperator | ||||
453 | : public ConcreteOperator<PossiblyExactOperator, Instruction::LShr> { | ||||
454 | }; | ||||
455 | |||||
456 | class ZExtOperator : public ConcreteOperator<Operator, Instruction::ZExt> {}; | ||||
457 | |||||
458 | class GEPOperator | ||||
459 | : public ConcreteOperator<Operator, Instruction::GetElementPtr> { | ||||
460 | friend class GetElementPtrInst; | ||||
461 | friend class ConstantExpr; | ||||
462 | |||||
463 | enum { | ||||
464 | IsInBounds = (1 << 0), | ||||
465 | // InRangeIndex: bits 1-6 | ||||
466 | }; | ||||
467 | |||||
468 | void setIsInBounds(bool B) { | ||||
469 | SubclassOptionalData = | ||||
470 | (SubclassOptionalData & ~IsInBounds) | (B * IsInBounds); | ||||
471 | } | ||||
472 | |||||
473 | public: | ||||
474 | /// Test whether this is an inbounds GEP, as defined by LangRef.html. | ||||
475 | bool isInBounds() const { | ||||
476 | return SubclassOptionalData & IsInBounds; | ||||
477 | } | ||||
478 | |||||
479 | /// Returns the offset of the index with an inrange attachment, or None if | ||||
480 | /// none. | ||||
481 | Optional<unsigned> getInRangeIndex() const { | ||||
482 | if (SubclassOptionalData >> 1 == 0) return None; | ||||
483 | return (SubclassOptionalData >> 1) - 1; | ||||
484 | } | ||||
485 | |||||
486 | inline op_iterator idx_begin() { return op_begin()+1; } | ||||
487 | inline const_op_iterator idx_begin() const { return op_begin()+1; } | ||||
488 | inline op_iterator idx_end() { return op_end(); } | ||||
489 | inline const_op_iterator idx_end() const { return op_end(); } | ||||
490 | |||||
491 | inline iterator_range<op_iterator> indices() { | ||||
492 | return make_range(idx_begin(), idx_end()); | ||||
493 | } | ||||
494 | |||||
495 | inline iterator_range<const_op_iterator> indices() const { | ||||
496 | return make_range(idx_begin(), idx_end()); | ||||
497 | } | ||||
498 | |||||
499 | Value *getPointerOperand() { | ||||
500 | return getOperand(0); | ||||
501 | } | ||||
502 | const Value *getPointerOperand() const { | ||||
503 | return getOperand(0); | ||||
504 | } | ||||
505 | static unsigned getPointerOperandIndex() { | ||||
506 | return 0U; // get index for modifying correct operand | ||||
507 | } | ||||
508 | |||||
509 | /// Method to return the pointer operand as a PointerType. | ||||
510 | Type *getPointerOperandType() const { | ||||
511 | return getPointerOperand()->getType(); | ||||
512 | } | ||||
513 | |||||
514 | Type *getSourceElementType() const; | ||||
515 | Type *getResultElementType() const; | ||||
516 | |||||
517 | /// Method to return the address space of the pointer operand. | ||||
518 | unsigned getPointerAddressSpace() const { | ||||
519 | return getPointerOperandType()->getPointerAddressSpace(); | ||||
520 | } | ||||
521 | |||||
522 | unsigned getNumIndices() const { // Note: always non-negative | ||||
523 | return getNumOperands() - 1; | ||||
524 | } | ||||
525 | |||||
526 | bool hasIndices() const { | ||||
527 | return getNumOperands() > 1; | ||||
528 | } | ||||
529 | |||||
530 | /// Return true if all of the indices of this GEP are zeros. | ||||
531 | /// If so, the result pointer and the first operand have the same | ||||
532 | /// value, just potentially different types. | ||||
533 | bool hasAllZeroIndices() const { | ||||
534 | for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) { | ||||
535 | if (ConstantInt *C = dyn_cast<ConstantInt>(I)) | ||||
536 | if (C->isZero()) | ||||
537 | continue; | ||||
538 | return false; | ||||
539 | } | ||||
540 | return true; | ||||
541 | } | ||||
542 | |||||
543 | /// Return true if all of the indices of this GEP are constant integers. | ||||
544 | /// If so, the result pointer and the first operand have | ||||
545 | /// a constant offset between them. | ||||
546 | bool hasAllConstantIndices() const { | ||||
547 | for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) { | ||||
548 | if (!isa<ConstantInt>(I)) | ||||
549 | return false; | ||||
550 | } | ||||
551 | return true; | ||||
552 | } | ||||
553 | |||||
554 | unsigned countNonConstantIndices() const { | ||||
555 | return count_if(indices(), [](const Use& use) { | ||||
556 | return !isa<ConstantInt>(*use); | ||||
557 | }); | ||||
558 | } | ||||
559 | |||||
560 | /// Compute the maximum alignment that this GEP is garranteed to preserve. | ||||
561 | Align getMaxPreservedAlignment(const DataLayout &DL) const; | ||||
562 | |||||
563 | /// Accumulate the constant address offset of this GEP if possible. | ||||
564 | /// | ||||
565 | /// This routine accepts an APInt into which it will try to accumulate the | ||||
566 | /// constant offset of this GEP. | ||||
567 | /// | ||||
568 | /// If \p ExternalAnalysis is provided it will be used to calculate a offset | ||||
569 | /// when a operand of GEP is not constant. | ||||
570 | /// For example, for a value \p ExternalAnalysis might try to calculate a | ||||
571 | /// lower bound. If \p ExternalAnalysis is successful, it should return true. | ||||
572 | /// | ||||
573 | /// If the \p ExternalAnalysis returns false or the value returned by \p | ||||
574 | /// ExternalAnalysis results in a overflow/underflow, this routine returns | ||||
575 | /// false and the value of the offset APInt is undefined (it is *not* | ||||
576 | /// preserved!). | ||||
577 | /// | ||||
578 | /// The APInt passed into this routine must be at exactly as wide as the | ||||
579 | /// IntPtr type for the address space of the base GEP pointer. | ||||
580 | bool accumulateConstantOffset( | ||||
581 | const DataLayout &DL, APInt &Offset, | ||||
582 | function_ref<bool(Value &, APInt &)> ExternalAnalysis = nullptr) const; | ||||
583 | |||||
584 | static bool accumulateConstantOffset( | ||||
585 | Type *SourceType, ArrayRef<const Value *> Index, const DataLayout &DL, | ||||
586 | APInt &Offset, | ||||
587 | function_ref<bool(Value &, APInt &)> ExternalAnalysis = nullptr); | ||||
588 | |||||
589 | /// Collect the offset of this GEP as a map of Values to their associated | ||||
590 | /// APInt multipliers, as well as a total Constant Offset. | ||||
591 | bool collectOffset(const DataLayout &DL, unsigned BitWidth, | ||||
592 | MapVector<Value *, APInt> &VariableOffsets, | ||||
593 | APInt &ConstantOffset) const; | ||||
594 | }; | ||||
595 | |||||
596 | class PtrToIntOperator | ||||
597 | : public ConcreteOperator<Operator, Instruction::PtrToInt> { | ||||
598 | friend class PtrToInt; | ||||
599 | friend class ConstantExpr; | ||||
600 | |||||
601 | public: | ||||
602 | Value *getPointerOperand() { | ||||
603 | return getOperand(0); | ||||
604 | } | ||||
605 | const Value *getPointerOperand() const { | ||||
606 | return getOperand(0); | ||||
607 | } | ||||
608 | |||||
609 | static unsigned getPointerOperandIndex() { | ||||
610 | return 0U; // get index for modifying correct operand | ||||
611 | } | ||||
612 | |||||
613 | /// Method to return the pointer operand as a PointerType. | ||||
614 | Type *getPointerOperandType() const { | ||||
615 | return getPointerOperand()->getType(); | ||||
616 | } | ||||
617 | |||||
618 | /// Method to return the address space of the pointer operand. | ||||
619 | unsigned getPointerAddressSpace() const { | ||||
620 | return cast<PointerType>(getPointerOperandType())->getAddressSpace(); | ||||
621 | } | ||||
622 | }; | ||||
623 | |||||
624 | class BitCastOperator | ||||
625 | : public ConcreteOperator<Operator, Instruction::BitCast> { | ||||
626 | friend class BitCastInst; | ||||
627 | friend class ConstantExpr; | ||||
628 | |||||
629 | public: | ||||
630 | Type *getSrcTy() const { | ||||
631 | return getOperand(0)->getType(); | ||||
632 | } | ||||
633 | |||||
634 | Type *getDestTy() const { | ||||
635 | return getType(); | ||||
636 | } | ||||
637 | }; | ||||
638 | |||||
639 | class AddrSpaceCastOperator | ||||
640 | : public ConcreteOperator<Operator, Instruction::AddrSpaceCast> { | ||||
641 | friend class AddrSpaceCastInst; | ||||
642 | friend class ConstantExpr; | ||||
643 | |||||
644 | public: | ||||
645 | Value *getPointerOperand() { return getOperand(0); } | ||||
646 | |||||
647 | const Value *getPointerOperand() const { return getOperand(0); } | ||||
648 | |||||
649 | unsigned getSrcAddressSpace() const { | ||||
650 | return getPointerOperand()->getType()->getPointerAddressSpace(); | ||||
651 | } | ||||
652 | |||||
653 | unsigned getDestAddressSpace() const { | ||||
654 | return getType()->getPointerAddressSpace(); | ||||
655 | } | ||||
656 | }; | ||||
657 | |||||
658 | } // end namespace llvm | ||||
659 | |||||
660 | #endif // LLVM_IR_OPERATOR_H |