File: | include/llvm/Analysis/ValueTracking.h |
Warning: | line 626, column 5 Assigned value is garbage or undefined |
Press '?' to see keyboard shortcuts
Keyboard shortcuts:
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/AssumptionCache.h" | |||
28 | #include "llvm/Analysis/GuardUtils.h" | |||
29 | #include "llvm/Analysis/InstructionSimplify.h" | |||
30 | #include "llvm/Analysis/Loads.h" | |||
31 | #include "llvm/Analysis/LoopInfo.h" | |||
32 | #include "llvm/Analysis/OptimizationRemarkEmitter.h" | |||
33 | #include "llvm/Analysis/TargetLibraryInfo.h" | |||
34 | #include "llvm/IR/Argument.h" | |||
35 | #include "llvm/IR/Attributes.h" | |||
36 | #include "llvm/IR/BasicBlock.h" | |||
37 | #include "llvm/IR/CallSite.h" | |||
38 | #include "llvm/IR/Constant.h" | |||
39 | #include "llvm/IR/ConstantRange.h" | |||
40 | #include "llvm/IR/Constants.h" | |||
41 | #include "llvm/IR/DerivedTypes.h" | |||
42 | #include "llvm/IR/DiagnosticInfo.h" | |||
43 | #include "llvm/IR/Dominators.h" | |||
44 | #include "llvm/IR/Function.h" | |||
45 | #include "llvm/IR/GetElementPtrTypeIterator.h" | |||
46 | #include "llvm/IR/GlobalAlias.h" | |||
47 | #include "llvm/IR/GlobalValue.h" | |||
48 | #include "llvm/IR/GlobalVariable.h" | |||
49 | #include "llvm/IR/InstrTypes.h" | |||
50 | #include "llvm/IR/Instruction.h" | |||
51 | #include "llvm/IR/Instructions.h" | |||
52 | #include "llvm/IR/IntrinsicInst.h" | |||
53 | #include "llvm/IR/Intrinsics.h" | |||
54 | #include "llvm/IR/LLVMContext.h" | |||
55 | #include "llvm/IR/Metadata.h" | |||
56 | #include "llvm/IR/Module.h" | |||
57 | #include "llvm/IR/Operator.h" | |||
58 | #include "llvm/IR/PatternMatch.h" | |||
59 | #include "llvm/IR/Type.h" | |||
60 | #include "llvm/IR/User.h" | |||
61 | #include "llvm/IR/Value.h" | |||
62 | #include "llvm/Support/Casting.h" | |||
63 | #include "llvm/Support/CommandLine.h" | |||
64 | #include "llvm/Support/Compiler.h" | |||
65 | #include "llvm/Support/ErrorHandling.h" | |||
66 | #include "llvm/Support/KnownBits.h" | |||
67 | #include "llvm/Support/MathExtras.h" | |||
68 | #include <algorithm> | |||
69 | #include <array> | |||
70 | #include <cassert> | |||
71 | #include <cstdint> | |||
72 | #include <iterator> | |||
73 | #include <utility> | |||
74 | ||||
75 | using namespace llvm; | |||
76 | using namespace llvm::PatternMatch; | |||
77 | ||||
78 | const unsigned MaxDepth = 6; | |||
79 | ||||
80 | // Controls the number of uses of the value searched for possible | |||
81 | // dominating comparisons. | |||
82 | static cl::opt<unsigned> DomConditionsMaxUses("dom-conditions-max-uses", | |||
83 | cl::Hidden, cl::init(20)); | |||
84 | ||||
85 | /// Returns the bitwidth of the given scalar or pointer type. For vector types, | |||
86 | /// returns the element type's bitwidth. | |||
87 | static unsigned getBitWidth(Type *Ty, const DataLayout &DL) { | |||
88 | if (unsigned BitWidth = Ty->getScalarSizeInBits()) | |||
89 | return BitWidth; | |||
90 | ||||
91 | return DL.getIndexTypeSizeInBits(Ty); | |||
92 | } | |||
93 | ||||
94 | namespace { | |||
95 | ||||
96 | // Simplifying using an assume can only be done in a particular control-flow | |||
97 | // context (the context instruction provides that context). If an assume and | |||
98 | // the context instruction are not in the same block then the DT helps in | |||
99 | // figuring out if we can use it. | |||
100 | struct Query { | |||
101 | const DataLayout &DL; | |||
102 | AssumptionCache *AC; | |||
103 | const Instruction *CxtI; | |||
104 | const DominatorTree *DT; | |||
105 | ||||
106 | // Unlike the other analyses, this may be a nullptr because not all clients | |||
107 | // provide it currently. | |||
108 | OptimizationRemarkEmitter *ORE; | |||
109 | ||||
110 | /// Set of assumptions that should be excluded from further queries. | |||
111 | /// This is because of the potential for mutual recursion to cause | |||
112 | /// computeKnownBits to repeatedly visit the same assume intrinsic. The | |||
113 | /// classic case of this is assume(x = y), which will attempt to determine | |||
114 | /// bits in x from bits in y, which will attempt to determine bits in y from | |||
115 | /// bits in x, etc. Regarding the mutual recursion, computeKnownBits can call | |||
116 | /// isKnownNonZero, which calls computeKnownBits and isKnownToBeAPowerOfTwo | |||
117 | /// (all of which can call computeKnownBits), and so on. | |||
118 | std::array<const Value *, MaxDepth> Excluded; | |||
119 | ||||
120 | /// If true, it is safe to use metadata during simplification. | |||
121 | InstrInfoQuery IIQ; | |||
122 | ||||
123 | unsigned NumExcluded = 0; | |||
124 | ||||
125 | Query(const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, | |||
126 | const DominatorTree *DT, bool UseInstrInfo, | |||
127 | OptimizationRemarkEmitter *ORE = nullptr) | |||
128 | : DL(DL), AC(AC), CxtI(CxtI), DT(DT), ORE(ORE), IIQ(UseInstrInfo) {} | |||
129 | ||||
130 | Query(const Query &Q, const Value *NewExcl) | |||
131 | : DL(Q.DL), AC(Q.AC), CxtI(Q.CxtI), DT(Q.DT), ORE(Q.ORE), IIQ(Q.IIQ), | |||
132 | NumExcluded(Q.NumExcluded) { | |||
133 | Excluded = Q.Excluded; | |||
134 | Excluded[NumExcluded++] = NewExcl; | |||
135 | assert(NumExcluded <= Excluded.size())((NumExcluded <= Excluded.size()) ? static_cast<void> (0) : __assert_fail ("NumExcluded <= Excluded.size()", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 135, __PRETTY_FUNCTION__)); | |||
136 | } | |||
137 | ||||
138 | bool isExcluded(const Value *Value) const { | |||
139 | if (NumExcluded == 0) | |||
140 | return false; | |||
141 | auto End = Excluded.begin() + NumExcluded; | |||
142 | return std::find(Excluded.begin(), End, Value) != End; | |||
143 | } | |||
144 | }; | |||
145 | ||||
146 | } // end anonymous namespace | |||
147 | ||||
148 | // Given the provided Value and, potentially, a context instruction, return | |||
149 | // the preferred context instruction (if any). | |||
150 | static const Instruction *safeCxtI(const Value *V, const Instruction *CxtI) { | |||
151 | // If we've been provided with a context instruction, then use that (provided | |||
152 | // it has been inserted). | |||
153 | if (CxtI && CxtI->getParent()) | |||
154 | return CxtI; | |||
155 | ||||
156 | // If the value is really an already-inserted instruction, then use that. | |||
157 | CxtI = dyn_cast<Instruction>(V); | |||
158 | if (CxtI && CxtI->getParent()) | |||
159 | return CxtI; | |||
160 | ||||
161 | return nullptr; | |||
162 | } | |||
163 | ||||
164 | static void computeKnownBits(const Value *V, KnownBits &Known, | |||
165 | unsigned Depth, const Query &Q); | |||
166 | ||||
167 | void llvm::computeKnownBits(const Value *V, KnownBits &Known, | |||
168 | const DataLayout &DL, unsigned Depth, | |||
169 | AssumptionCache *AC, const Instruction *CxtI, | |||
170 | const DominatorTree *DT, | |||
171 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { | |||
172 | ::computeKnownBits(V, Known, Depth, | |||
173 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
174 | } | |||
175 | ||||
176 | static KnownBits computeKnownBits(const Value *V, unsigned Depth, | |||
177 | const Query &Q); | |||
178 | ||||
179 | KnownBits llvm::computeKnownBits(const Value *V, const DataLayout &DL, | |||
180 | unsigned Depth, AssumptionCache *AC, | |||
181 | const Instruction *CxtI, | |||
182 | const DominatorTree *DT, | |||
183 | OptimizationRemarkEmitter *ORE, | |||
184 | bool UseInstrInfo) { | |||
185 | return ::computeKnownBits( | |||
186 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); | |||
187 | } | |||
188 | ||||
189 | bool llvm::haveNoCommonBitsSet(const Value *LHS, const Value *RHS, | |||
190 | const DataLayout &DL, AssumptionCache *AC, | |||
191 | const Instruction *CxtI, const DominatorTree *DT, | |||
192 | bool UseInstrInfo) { | |||
193 | assert(LHS->getType() == RHS->getType() &&((LHS->getType() == RHS->getType() && "LHS and RHS should have the same type" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 194, __PRETTY_FUNCTION__)) | |||
194 | "LHS and RHS should have the same type")((LHS->getType() == RHS->getType() && "LHS and RHS should have the same type" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 194, __PRETTY_FUNCTION__)); | |||
195 | assert(LHS->getType()->isIntOrIntVectorTy() &&((LHS->getType()->isIntOrIntVectorTy() && "LHS and RHS should be integers" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 196, __PRETTY_FUNCTION__)) | |||
196 | "LHS and RHS should be integers")((LHS->getType()->isIntOrIntVectorTy() && "LHS and RHS should be integers" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 196, __PRETTY_FUNCTION__)); | |||
197 | // Look for an inverted mask: (X & ~M) op (Y & M). | |||
198 | Value *M; | |||
199 | if (match(LHS, m_c_And(m_Not(m_Value(M)), m_Value())) && | |||
200 | match(RHS, m_c_And(m_Specific(M), m_Value()))) | |||
201 | return true; | |||
202 | if (match(RHS, m_c_And(m_Not(m_Value(M)), m_Value())) && | |||
203 | match(LHS, m_c_And(m_Specific(M), m_Value()))) | |||
204 | return true; | |||
205 | IntegerType *IT = cast<IntegerType>(LHS->getType()->getScalarType()); | |||
206 | KnownBits LHSKnown(IT->getBitWidth()); | |||
207 | KnownBits RHSKnown(IT->getBitWidth()); | |||
208 | computeKnownBits(LHS, LHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
209 | computeKnownBits(RHS, RHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
210 | return (LHSKnown.Zero | RHSKnown.Zero).isAllOnesValue(); | |||
211 | } | |||
212 | ||||
213 | bool llvm::isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI) { | |||
214 | for (const User *U : CxtI->users()) { | |||
215 | if (const ICmpInst *IC = dyn_cast<ICmpInst>(U)) | |||
216 | if (IC->isEquality()) | |||
217 | if (Constant *C = dyn_cast<Constant>(IC->getOperand(1))) | |||
218 | if (C->isNullValue()) | |||
219 | continue; | |||
220 | return false; | |||
221 | } | |||
222 | return true; | |||
223 | } | |||
224 | ||||
225 | static bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, | |||
226 | const Query &Q); | |||
227 | ||||
228 | bool llvm::isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL, | |||
229 | bool OrZero, unsigned Depth, | |||
230 | AssumptionCache *AC, const Instruction *CxtI, | |||
231 | const DominatorTree *DT, bool UseInstrInfo) { | |||
232 | return ::isKnownToBeAPowerOfTwo( | |||
233 | V, OrZero, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
234 | } | |||
235 | ||||
236 | static bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q); | |||
237 | ||||
238 | bool llvm::isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth, | |||
239 | AssumptionCache *AC, const Instruction *CxtI, | |||
240 | const DominatorTree *DT, bool UseInstrInfo) { | |||
241 | return ::isKnownNonZero(V, Depth, | |||
242 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
243 | } | |||
244 | ||||
245 | bool llvm::isKnownNonNegative(const Value *V, const DataLayout &DL, | |||
246 | unsigned Depth, AssumptionCache *AC, | |||
247 | const Instruction *CxtI, const DominatorTree *DT, | |||
248 | bool UseInstrInfo) { | |||
249 | KnownBits Known = | |||
250 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
251 | return Known.isNonNegative(); | |||
252 | } | |||
253 | ||||
254 | bool llvm::isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth, | |||
255 | AssumptionCache *AC, const Instruction *CxtI, | |||
256 | const DominatorTree *DT, bool UseInstrInfo) { | |||
257 | if (auto *CI = dyn_cast<ConstantInt>(V)) | |||
258 | return CI->getValue().isStrictlyPositive(); | |||
259 | ||||
260 | // TODO: We'd doing two recursive queries here. We should factor this such | |||
261 | // that only a single query is needed. | |||
262 | return isKnownNonNegative(V, DL, Depth, AC, CxtI, DT, UseInstrInfo) && | |||
263 | isKnownNonZero(V, DL, Depth, AC, CxtI, DT, UseInstrInfo); | |||
264 | } | |||
265 | ||||
266 | bool llvm::isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth, | |||
267 | AssumptionCache *AC, const Instruction *CxtI, | |||
268 | const DominatorTree *DT, bool UseInstrInfo) { | |||
269 | KnownBits Known = | |||
270 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); | |||
271 | return Known.isNegative(); | |||
272 | } | |||
273 | ||||
274 | static bool isKnownNonEqual(const Value *V1, const Value *V2, const Query &Q); | |||
275 | ||||
276 | bool llvm::isKnownNonEqual(const Value *V1, const Value *V2, | |||
277 | const DataLayout &DL, AssumptionCache *AC, | |||
278 | const Instruction *CxtI, const DominatorTree *DT, | |||
279 | bool UseInstrInfo) { | |||
280 | return ::isKnownNonEqual(V1, V2, | |||
281 | Query(DL, AC, safeCxtI(V1, safeCxtI(V2, CxtI)), DT, | |||
282 | UseInstrInfo, /*ORE=*/nullptr)); | |||
283 | } | |||
284 | ||||
285 | static bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, | |||
286 | const Query &Q); | |||
287 | ||||
288 | bool llvm::MaskedValueIsZero(const Value *V, const APInt &Mask, | |||
289 | const DataLayout &DL, unsigned Depth, | |||
290 | AssumptionCache *AC, const Instruction *CxtI, | |||
291 | const DominatorTree *DT, bool UseInstrInfo) { | |||
292 | return ::MaskedValueIsZero( | |||
293 | V, Mask, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
294 | } | |||
295 | ||||
296 | static unsigned ComputeNumSignBits(const Value *V, unsigned Depth, | |||
297 | const Query &Q); | |||
298 | ||||
299 | unsigned llvm::ComputeNumSignBits(const Value *V, const DataLayout &DL, | |||
300 | unsigned Depth, AssumptionCache *AC, | |||
301 | const Instruction *CxtI, | |||
302 | const DominatorTree *DT, bool UseInstrInfo) { | |||
303 | return ::ComputeNumSignBits( | |||
304 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); | |||
305 | } | |||
306 | ||||
307 | static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1, | |||
308 | bool NSW, | |||
309 | KnownBits &KnownOut, KnownBits &Known2, | |||
310 | unsigned Depth, const Query &Q) { | |||
311 | unsigned BitWidth = KnownOut.getBitWidth(); | |||
312 | ||||
313 | // If an initial sequence of bits in the result is not needed, the | |||
314 | // corresponding bits in the operands are not needed. | |||
315 | KnownBits LHSKnown(BitWidth); | |||
316 | computeKnownBits(Op0, LHSKnown, Depth + 1, Q); | |||
317 | computeKnownBits(Op1, Known2, Depth + 1, Q); | |||
318 | ||||
319 | KnownOut = KnownBits::computeForAddSub(Add, NSW, LHSKnown, Known2); | |||
320 | } | |||
321 | ||||
322 | static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW, | |||
323 | KnownBits &Known, KnownBits &Known2, | |||
324 | unsigned Depth, const Query &Q) { | |||
325 | unsigned BitWidth = Known.getBitWidth(); | |||
326 | computeKnownBits(Op1, Known, Depth + 1, Q); | |||
327 | computeKnownBits(Op0, Known2, Depth + 1, Q); | |||
328 | ||||
329 | bool isKnownNegative = false; | |||
330 | bool isKnownNonNegative = false; | |||
331 | // If the multiplication is known not to overflow, compute the sign bit. | |||
332 | if (NSW) { | |||
333 | if (Op0 == Op1) { | |||
334 | // The product of a number with itself is non-negative. | |||
335 | isKnownNonNegative = true; | |||
336 | } else { | |||
337 | bool isKnownNonNegativeOp1 = Known.isNonNegative(); | |||
338 | bool isKnownNonNegativeOp0 = Known2.isNonNegative(); | |||
339 | bool isKnownNegativeOp1 = Known.isNegative(); | |||
340 | bool isKnownNegativeOp0 = Known2.isNegative(); | |||
341 | // The product of two numbers with the same sign is non-negative. | |||
342 | isKnownNonNegative = (isKnownNegativeOp1 && isKnownNegativeOp0) || | |||
343 | (isKnownNonNegativeOp1 && isKnownNonNegativeOp0); | |||
344 | // The product of a negative number and a non-negative number is either | |||
345 | // negative or zero. | |||
346 | if (!isKnownNonNegative) | |||
347 | isKnownNegative = (isKnownNegativeOp1 && isKnownNonNegativeOp0 && | |||
348 | isKnownNonZero(Op0, Depth, Q)) || | |||
349 | (isKnownNegativeOp0 && isKnownNonNegativeOp1 && | |||
350 | isKnownNonZero(Op1, Depth, Q)); | |||
351 | } | |||
352 | } | |||
353 | ||||
354 | assert(!Known.hasConflict() && !Known2.hasConflict())((!Known.hasConflict() && !Known2.hasConflict()) ? static_cast <void> (0) : __assert_fail ("!Known.hasConflict() && !Known2.hasConflict()" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 354, __PRETTY_FUNCTION__)); | |||
355 | // Compute a conservative estimate for high known-0 bits. | |||
356 | unsigned LeadZ = std::max(Known.countMinLeadingZeros() + | |||
357 | Known2.countMinLeadingZeros(), | |||
358 | BitWidth) - BitWidth; | |||
359 | LeadZ = std::min(LeadZ, BitWidth); | |||
360 | ||||
361 | // The result of the bottom bits of an integer multiply can be | |||
362 | // inferred by looking at the bottom bits of both operands and | |||
363 | // multiplying them together. | |||
364 | // We can infer at least the minimum number of known trailing bits | |||
365 | // of both operands. Depending on number of trailing zeros, we can | |||
366 | // infer more bits, because (a*b) <=> ((a/m) * (b/n)) * (m*n) assuming | |||
367 | // a and b are divisible by m and n respectively. | |||
368 | // We then calculate how many of those bits are inferrable and set | |||
369 | // the output. For example, the i8 mul: | |||
370 | // a = XXXX1100 (12) | |||
371 | // b = XXXX1110 (14) | |||
372 | // We know the bottom 3 bits are zero since the first can be divided by | |||
373 | // 4 and the second by 2, thus having ((12/4) * (14/2)) * (2*4). | |||
374 | // Applying the multiplication to the trimmed arguments gets: | |||
375 | // XX11 (3) | |||
376 | // X111 (7) | |||
377 | // ------- | |||
378 | // XX11 | |||
379 | // XX11 | |||
380 | // XX11 | |||
381 | // XX11 | |||
382 | // ------- | |||
383 | // XXXXX01 | |||
384 | // Which allows us to infer the 2 LSBs. Since we're multiplying the result | |||
385 | // by 8, the bottom 3 bits will be 0, so we can infer a total of 5 bits. | |||
386 | // The proof for this can be described as: | |||
387 | // Pre: (C1 >= 0) && (C1 < (1 << C5)) && (C2 >= 0) && (C2 < (1 << C6)) && | |||
388 | // (C7 == (1 << (umin(countTrailingZeros(C1), C5) + | |||
389 | // umin(countTrailingZeros(C2), C6) + | |||
390 | // umin(C5 - umin(countTrailingZeros(C1), C5), | |||
391 | // C6 - umin(countTrailingZeros(C2), C6)))) - 1) | |||
392 | // %aa = shl i8 %a, C5 | |||
393 | // %bb = shl i8 %b, C6 | |||
394 | // %aaa = or i8 %aa, C1 | |||
395 | // %bbb = or i8 %bb, C2 | |||
396 | // %mul = mul i8 %aaa, %bbb | |||
397 | // %mask = and i8 %mul, C7 | |||
398 | // => | |||
399 | // %mask = i8 ((C1*C2)&C7) | |||
400 | // Where C5, C6 describe the known bits of %a, %b | |||
401 | // C1, C2 describe the known bottom bits of %a, %b. | |||
402 | // C7 describes the mask of the known bits of the result. | |||
403 | APInt Bottom0 = Known.One; | |||
404 | APInt Bottom1 = Known2.One; | |||
405 | ||||
406 | // How many times we'd be able to divide each argument by 2 (shr by 1). | |||
407 | // This gives us the number of trailing zeros on the multiplication result. | |||
408 | unsigned TrailBitsKnown0 = (Known.Zero | Known.One).countTrailingOnes(); | |||
409 | unsigned TrailBitsKnown1 = (Known2.Zero | Known2.One).countTrailingOnes(); | |||
410 | unsigned TrailZero0 = Known.countMinTrailingZeros(); | |||
411 | unsigned TrailZero1 = Known2.countMinTrailingZeros(); | |||
412 | unsigned TrailZ = TrailZero0 + TrailZero1; | |||
413 | ||||
414 | // Figure out the fewest known-bits operand. | |||
415 | unsigned SmallestOperand = std::min(TrailBitsKnown0 - TrailZero0, | |||
416 | TrailBitsKnown1 - TrailZero1); | |||
417 | unsigned ResultBitsKnown = std::min(SmallestOperand + TrailZ, BitWidth); | |||
418 | ||||
419 | APInt BottomKnown = Bottom0.getLoBits(TrailBitsKnown0) * | |||
420 | Bottom1.getLoBits(TrailBitsKnown1); | |||
421 | ||||
422 | Known.resetAll(); | |||
423 | Known.Zero.setHighBits(LeadZ); | |||
424 | Known.Zero |= (~BottomKnown).getLoBits(ResultBitsKnown); | |||
425 | Known.One |= BottomKnown.getLoBits(ResultBitsKnown); | |||
426 | ||||
427 | // Only make use of no-wrap flags if we failed to compute the sign bit | |||
428 | // directly. This matters if the multiplication always overflows, in | |||
429 | // which case we prefer to follow the result of the direct computation, | |||
430 | // though as the program is invoking undefined behaviour we can choose | |||
431 | // whatever we like here. | |||
432 | if (isKnownNonNegative && !Known.isNegative()) | |||
433 | Known.makeNonNegative(); | |||
434 | else if (isKnownNegative && !Known.isNonNegative()) | |||
435 | Known.makeNegative(); | |||
436 | } | |||
437 | ||||
438 | void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges, | |||
439 | KnownBits &Known) { | |||
440 | unsigned BitWidth = Known.getBitWidth(); | |||
441 | unsigned NumRanges = Ranges.getNumOperands() / 2; | |||
442 | assert(NumRanges >= 1)((NumRanges >= 1) ? static_cast<void> (0) : __assert_fail ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 442, __PRETTY_FUNCTION__)); | |||
443 | ||||
444 | Known.Zero.setAllBits(); | |||
445 | Known.One.setAllBits(); | |||
446 | ||||
447 | for (unsigned i = 0; i < NumRanges; ++i) { | |||
448 | ConstantInt *Lower = | |||
449 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 0)); | |||
450 | ConstantInt *Upper = | |||
451 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1)); | |||
452 | ConstantRange Range(Lower->getValue(), Upper->getValue()); | |||
453 | ||||
454 | // The first CommonPrefixBits of all values in Range are equal. | |||
455 | unsigned CommonPrefixBits = | |||
456 | (Range.getUnsignedMax() ^ Range.getUnsignedMin()).countLeadingZeros(); | |||
457 | ||||
458 | APInt Mask = APInt::getHighBitsSet(BitWidth, CommonPrefixBits); | |||
459 | Known.One &= Range.getUnsignedMax() & Mask; | |||
460 | Known.Zero &= ~Range.getUnsignedMax() & Mask; | |||
461 | } | |||
462 | } | |||
463 | ||||
464 | static bool isEphemeralValueOf(const Instruction *I, const Value *E) { | |||
465 | SmallVector<const Value *, 16> WorkSet(1, I); | |||
466 | SmallPtrSet<const Value *, 32> Visited; | |||
467 | SmallPtrSet<const Value *, 16> EphValues; | |||
468 | ||||
469 | // The instruction defining an assumption's condition itself is always | |||
470 | // considered ephemeral to that assumption (even if it has other | |||
471 | // non-ephemeral users). See r246696's test case for an example. | |||
472 | if (is_contained(I->operands(), E)) | |||
473 | return true; | |||
474 | ||||
475 | while (!WorkSet.empty()) { | |||
476 | const Value *V = WorkSet.pop_back_val(); | |||
477 | if (!Visited.insert(V).second) | |||
478 | continue; | |||
479 | ||||
480 | // If all uses of this value are ephemeral, then so is this value. | |||
481 | if (llvm::all_of(V->users(), [&](const User *U) { | |||
482 | return EphValues.count(U); | |||
483 | })) { | |||
484 | if (V == E) | |||
485 | return true; | |||
486 | ||||
487 | if (V == I || isSafeToSpeculativelyExecute(V)) { | |||
488 | EphValues.insert(V); | |||
489 | if (const User *U = dyn_cast<User>(V)) | |||
490 | for (User::const_op_iterator J = U->op_begin(), JE = U->op_end(); | |||
491 | J != JE; ++J) | |||
492 | WorkSet.push_back(*J); | |||
493 | } | |||
494 | } | |||
495 | } | |||
496 | ||||
497 | return false; | |||
498 | } | |||
499 | ||||
500 | // Is this an intrinsic that cannot be speculated but also cannot trap? | |||
501 | bool llvm::isAssumeLikeIntrinsic(const Instruction *I) { | |||
502 | if (const CallInst *CI = dyn_cast<CallInst>(I)) | |||
503 | if (Function *F = CI->getCalledFunction()) | |||
504 | switch (F->getIntrinsicID()) { | |||
505 | default: break; | |||
506 | // FIXME: This list is repeated from NoTTI::getIntrinsicCost. | |||
507 | case Intrinsic::assume: | |||
508 | case Intrinsic::sideeffect: | |||
509 | case Intrinsic::dbg_declare: | |||
510 | case Intrinsic::dbg_value: | |||
511 | case Intrinsic::dbg_label: | |||
512 | case Intrinsic::invariant_start: | |||
513 | case Intrinsic::invariant_end: | |||
514 | case Intrinsic::lifetime_start: | |||
515 | case Intrinsic::lifetime_end: | |||
516 | case Intrinsic::objectsize: | |||
517 | case Intrinsic::ptr_annotation: | |||
518 | case Intrinsic::var_annotation: | |||
519 | return true; | |||
520 | } | |||
521 | ||||
522 | return false; | |||
523 | } | |||
524 | ||||
525 | bool llvm::isValidAssumeForContext(const Instruction *Inv, | |||
526 | const Instruction *CxtI, | |||
527 | const DominatorTree *DT) { | |||
528 | // There are two restrictions on the use of an assume: | |||
529 | // 1. The assume must dominate the context (or the control flow must | |||
530 | // reach the assume whenever it reaches the context). | |||
531 | // 2. The context must not be in the assume's set of ephemeral values | |||
532 | // (otherwise we will use the assume to prove that the condition | |||
533 | // feeding the assume is trivially true, thus causing the removal of | |||
534 | // the assume). | |||
535 | ||||
536 | if (DT) { | |||
537 | if (DT->dominates(Inv, CxtI)) | |||
538 | return true; | |||
539 | } else if (Inv->getParent() == CxtI->getParent()->getSinglePredecessor()) { | |||
540 | // We don't have a DT, but this trivially dominates. | |||
541 | return true; | |||
542 | } | |||
543 | ||||
544 | // With or without a DT, the only remaining case we will check is if the | |||
545 | // instructions are in the same BB. Give up if that is not the case. | |||
546 | if (Inv->getParent() != CxtI->getParent()) | |||
547 | return false; | |||
548 | ||||
549 | // If we have a dom tree, then we now know that the assume doesn't dominate | |||
550 | // the other instruction. If we don't have a dom tree then we can check if | |||
551 | // the assume is first in the BB. | |||
552 | if (!DT) { | |||
553 | // Search forward from the assume until we reach the context (or the end | |||
554 | // of the block); the common case is that the assume will come first. | |||
555 | for (auto I = std::next(BasicBlock::const_iterator(Inv)), | |||
556 | IE = Inv->getParent()->end(); I != IE; ++I) | |||
557 | if (&*I == CxtI) | |||
558 | return true; | |||
559 | } | |||
560 | ||||
561 | // Don't let an assume affect itself - this would cause the problems | |||
562 | // `isEphemeralValueOf` is trying to prevent, and it would also make | |||
563 | // the loop below go out of bounds. | |||
564 | if (Inv == CxtI) | |||
565 | return false; | |||
566 | ||||
567 | // The context comes first, but they're both in the same block. Make sure | |||
568 | // there is nothing in between that might interrupt the control flow. | |||
569 | for (BasicBlock::const_iterator I = | |||
570 | std::next(BasicBlock::const_iterator(CxtI)), IE(Inv); | |||
571 | I != IE; ++I) | |||
572 | if (!isGuaranteedToTransferExecutionToSuccessor(&*I)) | |||
573 | return false; | |||
574 | ||||
575 | return !isEphemeralValueOf(Inv, CxtI); | |||
576 | } | |||
577 | ||||
578 | static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known, | |||
579 | unsigned Depth, const Query &Q) { | |||
580 | // Use of assumptions is context-sensitive. If we don't have a context, we | |||
581 | // cannot use them! | |||
582 | if (!Q.AC || !Q.CxtI) | |||
583 | return; | |||
584 | ||||
585 | unsigned BitWidth = Known.getBitWidth(); | |||
586 | ||||
587 | // Note that the patterns below need to be kept in sync with the code | |||
588 | // in AssumptionCache::updateAffectedValues. | |||
589 | ||||
590 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { | |||
591 | if (!AssumeVH) | |||
592 | continue; | |||
593 | CallInst *I = cast<CallInst>(AssumeVH); | |||
594 | assert(I->getParent()->getParent() == Q.CxtI->getParent()->getParent() &&((I->getParent()->getParent() == Q.CxtI->getParent() ->getParent() && "Got assumption for the wrong function!" ) ? static_cast<void> (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 595, __PRETTY_FUNCTION__)) | |||
595 | "Got assumption for the wrong function!")((I->getParent()->getParent() == Q.CxtI->getParent() ->getParent() && "Got assumption for the wrong function!" ) ? static_cast<void> (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 595, __PRETTY_FUNCTION__)); | |||
596 | if (Q.isExcluded(I)) | |||
597 | continue; | |||
598 | ||||
599 | // Warning: This loop can end up being somewhat performance sensitive. | |||
600 | // We're running this loop for once for each value queried resulting in a | |||
601 | // runtime of ~O(#assumes * #values). | |||
602 | ||||
603 | assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&((I->getCalledFunction()->getIntrinsicID() == Intrinsic ::assume && "must be an assume intrinsic") ? static_cast <void> (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 604, __PRETTY_FUNCTION__)) | |||
604 | "must be an assume intrinsic")((I->getCalledFunction()->getIntrinsicID() == Intrinsic ::assume && "must be an assume intrinsic") ? static_cast <void> (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 604, __PRETTY_FUNCTION__)); | |||
605 | ||||
606 | Value *Arg = I->getArgOperand(0); | |||
607 | ||||
608 | if (Arg == V && isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
609 | assert(BitWidth == 1 && "assume operand is not i1?")((BitWidth == 1 && "assume operand is not i1?") ? static_cast <void> (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 609, __PRETTY_FUNCTION__)); | |||
610 | Known.setAllOnes(); | |||
611 | return; | |||
612 | } | |||
613 | if (match(Arg, m_Not(m_Specific(V))) && | |||
614 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
615 | assert(BitWidth == 1 && "assume operand is not i1?")((BitWidth == 1 && "assume operand is not i1?") ? static_cast <void> (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 615, __PRETTY_FUNCTION__)); | |||
616 | Known.setAllZero(); | |||
617 | return; | |||
618 | } | |||
619 | ||||
620 | // The remaining tests are all recursive, so bail out if we hit the limit. | |||
621 | if (Depth == MaxDepth) | |||
622 | continue; | |||
623 | ||||
624 | ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg); | |||
625 | if (!Cmp) | |||
626 | continue; | |||
627 | ||||
628 | Value *A, *B; | |||
629 | auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V))); | |||
630 | ||||
631 | CmpInst::Predicate Pred; | |||
632 | uint64_t C; | |||
633 | switch (Cmp->getPredicate()) { | |||
634 | default: | |||
635 | break; | |||
636 | case ICmpInst::ICMP_EQ: | |||
637 | // assume(v = a) | |||
638 | if (match(Cmp, m_c_ICmp(Pred, m_V, m_Value(A))) && | |||
639 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
640 | KnownBits RHSKnown(BitWidth); | |||
641 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
642 | Known.Zero |= RHSKnown.Zero; | |||
643 | Known.One |= RHSKnown.One; | |||
644 | // assume(v & b = a) | |||
645 | } else if (match(Cmp, | |||
646 | m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)), m_Value(A))) && | |||
647 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
648 | KnownBits RHSKnown(BitWidth); | |||
649 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
650 | KnownBits MaskKnown(BitWidth); | |||
651 | computeKnownBits(B, MaskKnown, Depth+1, Query(Q, I)); | |||
652 | ||||
653 | // For those bits in the mask that are known to be one, we can propagate | |||
654 | // known bits from the RHS to V. | |||
655 | Known.Zero |= RHSKnown.Zero & MaskKnown.One; | |||
656 | Known.One |= RHSKnown.One & MaskKnown.One; | |||
657 | // assume(~(v & b) = a) | |||
658 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))), | |||
659 | m_Value(A))) && | |||
660 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
661 | KnownBits RHSKnown(BitWidth); | |||
662 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
663 | KnownBits MaskKnown(BitWidth); | |||
664 | computeKnownBits(B, MaskKnown, Depth+1, Query(Q, I)); | |||
665 | ||||
666 | // For those bits in the mask that are known to be one, we can propagate | |||
667 | // inverted known bits from the RHS to V. | |||
668 | Known.Zero |= RHSKnown.One & MaskKnown.One; | |||
669 | Known.One |= RHSKnown.Zero & MaskKnown.One; | |||
670 | // assume(v | b = a) | |||
671 | } else if (match(Cmp, | |||
672 | m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), m_Value(A))) && | |||
673 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
674 | KnownBits RHSKnown(BitWidth); | |||
675 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
676 | KnownBits BKnown(BitWidth); | |||
677 | computeKnownBits(B, BKnown, Depth+1, Query(Q, I)); | |||
678 | ||||
679 | // For those bits in B that are known to be zero, we can propagate known | |||
680 | // bits from the RHS to V. | |||
681 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; | |||
682 | Known.One |= RHSKnown.One & BKnown.Zero; | |||
683 | // assume(~(v | b) = a) | |||
684 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))), | |||
685 | m_Value(A))) && | |||
686 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
687 | KnownBits RHSKnown(BitWidth); | |||
688 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
689 | KnownBits BKnown(BitWidth); | |||
690 | computeKnownBits(B, BKnown, Depth+1, Query(Q, I)); | |||
691 | ||||
692 | // For those bits in B that are known to be zero, we can propagate | |||
693 | // inverted known bits from the RHS to V. | |||
694 | Known.Zero |= RHSKnown.One & BKnown.Zero; | |||
695 | Known.One |= RHSKnown.Zero & BKnown.Zero; | |||
696 | // assume(v ^ b = a) | |||
697 | } else if (match(Cmp, | |||
698 | m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), m_Value(A))) && | |||
699 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
700 | KnownBits RHSKnown(BitWidth); | |||
701 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
702 | KnownBits BKnown(BitWidth); | |||
703 | computeKnownBits(B, BKnown, Depth+1, Query(Q, I)); | |||
704 | ||||
705 | // For those bits in B that are known to be zero, we can propagate known | |||
706 | // bits from the RHS to V. For those bits in B that are known to be one, | |||
707 | // we can propagate inverted known bits from the RHS to V. | |||
708 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; | |||
709 | Known.One |= RHSKnown.One & BKnown.Zero; | |||
710 | Known.Zero |= RHSKnown.One & BKnown.One; | |||
711 | Known.One |= RHSKnown.Zero & BKnown.One; | |||
712 | // assume(~(v ^ b) = a) | |||
713 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))), | |||
714 | m_Value(A))) && | |||
715 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
716 | KnownBits RHSKnown(BitWidth); | |||
717 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
718 | KnownBits BKnown(BitWidth); | |||
719 | computeKnownBits(B, BKnown, Depth+1, Query(Q, I)); | |||
720 | ||||
721 | // For those bits in B that are known to be zero, we can propagate | |||
722 | // inverted known bits from the RHS to V. For those bits in B that are | |||
723 | // known to be one, we can propagate known bits from the RHS to V. | |||
724 | Known.Zero |= RHSKnown.One & BKnown.Zero; | |||
725 | Known.One |= RHSKnown.Zero & BKnown.Zero; | |||
726 | Known.Zero |= RHSKnown.Zero & BKnown.One; | |||
727 | Known.One |= RHSKnown.One & BKnown.One; | |||
728 | // assume(v << c = a) | |||
729 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)), | |||
730 | m_Value(A))) && | |||
731 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
732 | KnownBits RHSKnown(BitWidth); | |||
733 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
734 | // For those bits in RHS that are known, we can propagate them to known | |||
735 | // bits in V shifted to the right by C. | |||
736 | RHSKnown.Zero.lshrInPlace(C); | |||
737 | Known.Zero |= RHSKnown.Zero; | |||
738 | RHSKnown.One.lshrInPlace(C); | |||
739 | Known.One |= RHSKnown.One; | |||
740 | // assume(~(v << c) = a) | |||
741 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))), | |||
742 | m_Value(A))) && | |||
743 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
744 | KnownBits RHSKnown(BitWidth); | |||
745 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
746 | // For those bits in RHS that are known, we can propagate them inverted | |||
747 | // to known bits in V shifted to the right by C. | |||
748 | RHSKnown.One.lshrInPlace(C); | |||
749 | Known.Zero |= RHSKnown.One; | |||
750 | RHSKnown.Zero.lshrInPlace(C); | |||
751 | Known.One |= RHSKnown.Zero; | |||
752 | // assume(v >> c = a) | |||
753 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shr(m_V, m_ConstantInt(C)), | |||
754 | m_Value(A))) && | |||
755 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
756 | KnownBits RHSKnown(BitWidth); | |||
757 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
758 | // For those bits in RHS that are known, we can propagate them to known | |||
759 | // bits in V shifted to the right by C. | |||
760 | Known.Zero |= RHSKnown.Zero << C; | |||
761 | Known.One |= RHSKnown.One << C; | |||
762 | // assume(~(v >> c) = a) | |||
763 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shr(m_V, m_ConstantInt(C))), | |||
764 | m_Value(A))) && | |||
765 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { | |||
766 | KnownBits RHSKnown(BitWidth); | |||
767 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
768 | // For those bits in RHS that are known, we can propagate them inverted | |||
769 | // to known bits in V shifted to the right by C. | |||
770 | Known.Zero |= RHSKnown.One << C; | |||
771 | Known.One |= RHSKnown.Zero << C; | |||
772 | } | |||
773 | break; | |||
774 | case ICmpInst::ICMP_SGE: | |||
775 | // assume(v >=_s c) where c is non-negative | |||
776 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
777 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
778 | KnownBits RHSKnown(BitWidth); | |||
779 | computeKnownBits(A, RHSKnown, Depth + 1, Query(Q, I)); | |||
780 | ||||
781 | if (RHSKnown.isNonNegative()) { | |||
782 | // We know that the sign bit is zero. | |||
783 | Known.makeNonNegative(); | |||
784 | } | |||
785 | } | |||
786 | break; | |||
787 | case ICmpInst::ICMP_SGT: | |||
788 | // assume(v >_s c) where c is at least -1. | |||
789 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
790 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
791 | KnownBits RHSKnown(BitWidth); | |||
792 | computeKnownBits(A, RHSKnown, Depth + 1, Query(Q, I)); | |||
793 | ||||
794 | if (RHSKnown.isAllOnes() || RHSKnown.isNonNegative()) { | |||
795 | // We know that the sign bit is zero. | |||
796 | Known.makeNonNegative(); | |||
797 | } | |||
798 | } | |||
799 | break; | |||
800 | case ICmpInst::ICMP_SLE: | |||
801 | // assume(v <=_s c) where c is negative | |||
802 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
803 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
804 | KnownBits RHSKnown(BitWidth); | |||
805 | computeKnownBits(A, RHSKnown, Depth + 1, Query(Q, I)); | |||
806 | ||||
807 | if (RHSKnown.isNegative()) { | |||
808 | // We know that the sign bit is one. | |||
809 | Known.makeNegative(); | |||
810 | } | |||
811 | } | |||
812 | break; | |||
813 | case ICmpInst::ICMP_SLT: | |||
814 | // assume(v <_s c) where c is non-positive | |||
815 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
816 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
817 | KnownBits RHSKnown(BitWidth); | |||
818 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
819 | ||||
820 | if (RHSKnown.isZero() || RHSKnown.isNegative()) { | |||
821 | // We know that the sign bit is one. | |||
822 | Known.makeNegative(); | |||
823 | } | |||
824 | } | |||
825 | break; | |||
826 | case ICmpInst::ICMP_ULE: | |||
827 | // assume(v <=_u c) | |||
828 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
829 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
830 | KnownBits RHSKnown(BitWidth); | |||
831 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
832 | ||||
833 | // Whatever high bits in c are zero are known to be zero. | |||
834 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); | |||
835 | } | |||
836 | break; | |||
837 | case ICmpInst::ICMP_ULT: | |||
838 | // assume(v <_u c) | |||
839 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && | |||
840 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { | |||
841 | KnownBits RHSKnown(BitWidth); | |||
842 | computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); | |||
843 | ||||
844 | // If the RHS is known zero, then this assumption must be wrong (nothing | |||
845 | // is unsigned less than zero). Signal a conflict and get out of here. | |||
846 | if (RHSKnown.isZero()) { | |||
847 | Known.Zero.setAllBits(); | |||
848 | Known.One.setAllBits(); | |||
849 | break; | |||
850 | } | |||
851 | ||||
852 | // Whatever high bits in c are zero are known to be zero (if c is a power | |||
853 | // of 2, then one more). | |||
854 | if (isKnownToBeAPowerOfTwo(A, false, Depth + 1, Query(Q, I))) | |||
855 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros() + 1); | |||
856 | else | |||
857 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); | |||
858 | } | |||
859 | break; | |||
860 | } | |||
861 | } | |||
862 | ||||
863 | // If assumptions conflict with each other or previous known bits, then we | |||
864 | // have a logical fallacy. It's possible that the assumption is not reachable, | |||
865 | // so this isn't a real bug. On the other hand, the program may have undefined | |||
866 | // behavior, or we might have a bug in the compiler. We can't assert/crash, so | |||
867 | // clear out the known bits, try to warn the user, and hope for the best. | |||
868 | if (Known.Zero.intersects(Known.One)) { | |||
869 | Known.resetAll(); | |||
870 | ||||
871 | if (Q.ORE) | |||
872 | Q.ORE->emit([&]() { | |||
873 | auto *CxtI = const_cast<Instruction *>(Q.CxtI); | |||
874 | return OptimizationRemarkAnalysis("value-tracking", "BadAssumption", | |||
875 | CxtI) | |||
876 | << "Detected conflicting code assumptions. Program may " | |||
877 | "have undefined behavior, or compiler may have " | |||
878 | "internal error."; | |||
879 | }); | |||
880 | } | |||
881 | } | |||
882 | ||||
883 | /// Compute known bits from a shift operator, including those with a | |||
884 | /// non-constant shift amount. Known is the output of this function. Known2 is a | |||
885 | /// pre-allocated temporary with the same bit width as Known. KZF and KOF are | |||
886 | /// operator-specific functions that, given the known-zero or known-one bits | |||
887 | /// respectively, and a shift amount, compute the implied known-zero or | |||
888 | /// known-one bits of the shift operator's result respectively for that shift | |||
889 | /// amount. The results from calling KZF and KOF are conservatively combined for | |||
890 | /// all permitted shift amounts. | |||
891 | static void computeKnownBitsFromShiftOperator( | |||
892 | const Operator *I, KnownBits &Known, KnownBits &Known2, | |||
893 | unsigned Depth, const Query &Q, | |||
894 | function_ref<APInt(const APInt &, unsigned)> KZF, | |||
895 | function_ref<APInt(const APInt &, unsigned)> KOF) { | |||
896 | unsigned BitWidth = Known.getBitWidth(); | |||
897 | ||||
898 | if (auto *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { | |||
899 | unsigned ShiftAmt = SA->getLimitedValue(BitWidth-1); | |||
900 | ||||
901 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
902 | Known.Zero = KZF(Known.Zero, ShiftAmt); | |||
903 | Known.One = KOF(Known.One, ShiftAmt); | |||
904 | // If the known bits conflict, this must be an overflowing left shift, so | |||
905 | // the shift result is poison. We can return anything we want. Choose 0 for | |||
906 | // the best folding opportunity. | |||
907 | if (Known.hasConflict()) | |||
908 | Known.setAllZero(); | |||
909 | ||||
910 | return; | |||
911 | } | |||
912 | ||||
913 | computeKnownBits(I->getOperand(1), Known, Depth + 1, Q); | |||
914 | ||||
915 | // If the shift amount could be greater than or equal to the bit-width of the | |||
916 | // LHS, the value could be poison, but bail out because the check below is | |||
917 | // expensive. TODO: Should we just carry on? | |||
918 | if ((~Known.Zero).uge(BitWidth)) { | |||
919 | Known.resetAll(); | |||
920 | return; | |||
921 | } | |||
922 | ||||
923 | // Note: We cannot use Known.Zero.getLimitedValue() here, because if | |||
924 | // BitWidth > 64 and any upper bits are known, we'll end up returning the | |||
925 | // limit value (which implies all bits are known). | |||
926 | uint64_t ShiftAmtKZ = Known.Zero.zextOrTrunc(64).getZExtValue(); | |||
927 | uint64_t ShiftAmtKO = Known.One.zextOrTrunc(64).getZExtValue(); | |||
928 | ||||
929 | // It would be more-clearly correct to use the two temporaries for this | |||
930 | // calculation. Reusing the APInts here to prevent unnecessary allocations. | |||
931 | Known.resetAll(); | |||
932 | ||||
933 | // If we know the shifter operand is nonzero, we can sometimes infer more | |||
934 | // known bits. However this is expensive to compute, so be lazy about it and | |||
935 | // only compute it when absolutely necessary. | |||
936 | Optional<bool> ShifterOperandIsNonZero; | |||
937 | ||||
938 | // Early exit if we can't constrain any well-defined shift amount. | |||
939 | if (!(ShiftAmtKZ & (PowerOf2Ceil(BitWidth) - 1)) && | |||
940 | !(ShiftAmtKO & (PowerOf2Ceil(BitWidth) - 1))) { | |||
941 | ShifterOperandIsNonZero = isKnownNonZero(I->getOperand(1), Depth + 1, Q); | |||
942 | if (!*ShifterOperandIsNonZero) | |||
943 | return; | |||
944 | } | |||
945 | ||||
946 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
947 | ||||
948 | Known.Zero.setAllBits(); | |||
949 | Known.One.setAllBits(); | |||
950 | for (unsigned ShiftAmt = 0; ShiftAmt < BitWidth; ++ShiftAmt) { | |||
951 | // Combine the shifted known input bits only for those shift amounts | |||
952 | // compatible with its known constraints. | |||
953 | if ((ShiftAmt & ~ShiftAmtKZ) != ShiftAmt) | |||
954 | continue; | |||
955 | if ((ShiftAmt | ShiftAmtKO) != ShiftAmt) | |||
956 | continue; | |||
957 | // If we know the shifter is nonzero, we may be able to infer more known | |||
958 | // bits. This check is sunk down as far as possible to avoid the expensive | |||
959 | // call to isKnownNonZero if the cheaper checks above fail. | |||
960 | if (ShiftAmt == 0) { | |||
961 | if (!ShifterOperandIsNonZero.hasValue()) | |||
962 | ShifterOperandIsNonZero = | |||
963 | isKnownNonZero(I->getOperand(1), Depth + 1, Q); | |||
964 | if (*ShifterOperandIsNonZero) | |||
965 | continue; | |||
966 | } | |||
967 | ||||
968 | Known.Zero &= KZF(Known2.Zero, ShiftAmt); | |||
969 | Known.One &= KOF(Known2.One, ShiftAmt); | |||
970 | } | |||
971 | ||||
972 | // If the known bits conflict, the result is poison. Return a 0 and hope the | |||
973 | // caller can further optimize that. | |||
974 | if (Known.hasConflict()) | |||
975 | Known.setAllZero(); | |||
976 | } | |||
977 | ||||
978 | static void computeKnownBitsFromOperator(const Operator *I, KnownBits &Known, | |||
979 | unsigned Depth, const Query &Q) { | |||
980 | unsigned BitWidth = Known.getBitWidth(); | |||
981 | ||||
982 | KnownBits Known2(Known); | |||
983 | switch (I->getOpcode()) { | |||
| ||||
984 | default: break; | |||
985 | case Instruction::Load: | |||
986 | if (MDNode *MD = | |||
987 | Q.IIQ.getMetadata(cast<LoadInst>(I), LLVMContext::MD_range)) | |||
988 | computeKnownBitsFromRangeMetadata(*MD, Known); | |||
989 | break; | |||
990 | case Instruction::And: { | |||
991 | // If either the LHS or the RHS are Zero, the result is zero. | |||
992 | computeKnownBits(I->getOperand(1), Known, Depth + 1, Q); | |||
993 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
994 | ||||
995 | // Output known-1 bits are only known if set in both the LHS & RHS. | |||
996 | Known.One &= Known2.One; | |||
997 | // Output known-0 are known to be clear if zero in either the LHS | RHS. | |||
998 | Known.Zero |= Known2.Zero; | |||
999 | ||||
1000 | // and(x, add (x, -1)) is a common idiom that always clears the low bit; | |||
1001 | // here we handle the more general case of adding any odd number by | |||
1002 | // matching the form add(x, add(x, y)) where y is odd. | |||
1003 | // TODO: This could be generalized to clearing any bit set in y where the | |||
1004 | // following bit is known to be unset in y. | |||
1005 | Value *X = nullptr, *Y = nullptr; | |||
1006 | if (!Known.Zero[0] && !Known.One[0] && | |||
1007 | match(I, m_c_BinOp(m_Value(X), m_Add(m_Deferred(X), m_Value(Y))))) { | |||
1008 | Known2.resetAll(); | |||
1009 | computeKnownBits(Y, Known2, Depth + 1, Q); | |||
1010 | if (Known2.countMinTrailingOnes() > 0) | |||
1011 | Known.Zero.setBit(0); | |||
1012 | } | |||
1013 | break; | |||
1014 | } | |||
1015 | case Instruction::Or: | |||
1016 | computeKnownBits(I->getOperand(1), Known, Depth + 1, Q); | |||
1017 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1018 | ||||
1019 | // Output known-0 bits are only known if clear in both the LHS & RHS. | |||
1020 | Known.Zero &= Known2.Zero; | |||
1021 | // Output known-1 are known to be set if set in either the LHS | RHS. | |||
1022 | Known.One |= Known2.One; | |||
1023 | break; | |||
1024 | case Instruction::Xor: { | |||
1025 | computeKnownBits(I->getOperand(1), Known, Depth + 1, Q); | |||
1026 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1027 | ||||
1028 | // Output known-0 bits are known if clear or set in both the LHS & RHS. | |||
1029 | APInt KnownZeroOut = (Known.Zero & Known2.Zero) | (Known.One & Known2.One); | |||
1030 | // Output known-1 are known to be set if set in only one of the LHS, RHS. | |||
1031 | Known.One = (Known.Zero & Known2.One) | (Known.One & Known2.Zero); | |||
1032 | Known.Zero = std::move(KnownZeroOut); | |||
1033 | break; | |||
1034 | } | |||
1035 | case Instruction::Mul: { | |||
1036 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1037 | computeKnownBitsMul(I->getOperand(0), I->getOperand(1), NSW, Known, | |||
1038 | Known2, Depth, Q); | |||
1039 | break; | |||
1040 | } | |||
1041 | case Instruction::UDiv: { | |||
1042 | // For the purposes of computing leading zeros we can conservatively | |||
1043 | // treat a udiv as a logical right shift by the power of 2 known to | |||
1044 | // be less than the denominator. | |||
1045 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1046 | unsigned LeadZ = Known2.countMinLeadingZeros(); | |||
1047 | ||||
1048 | Known2.resetAll(); | |||
1049 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1050 | unsigned RHSMaxLeadingZeros = Known2.countMaxLeadingZeros(); | |||
1051 | if (RHSMaxLeadingZeros != BitWidth) | |||
1052 | LeadZ = std::min(BitWidth, LeadZ + BitWidth - RHSMaxLeadingZeros - 1); | |||
1053 | ||||
1054 | Known.Zero.setHighBits(LeadZ); | |||
1055 | break; | |||
1056 | } | |||
1057 | case Instruction::Select: { | |||
1058 | const Value *LHS, *RHS; | |||
1059 | SelectPatternFlavor SPF = matchSelectPattern(I, LHS, RHS).Flavor; | |||
1060 | if (SelectPatternResult::isMinOrMax(SPF)) { | |||
1061 | computeKnownBits(RHS, Known, Depth + 1, Q); | |||
1062 | computeKnownBits(LHS, Known2, Depth + 1, Q); | |||
1063 | } else { | |||
1064 | computeKnownBits(I->getOperand(2), Known, Depth + 1, Q); | |||
1065 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1066 | } | |||
1067 | ||||
1068 | unsigned MaxHighOnes = 0; | |||
1069 | unsigned MaxHighZeros = 0; | |||
1070 | if (SPF == SPF_SMAX) { | |||
1071 | // If both sides are negative, the result is negative. | |||
1072 | if (Known.isNegative() && Known2.isNegative()) | |||
1073 | // We can derive a lower bound on the result by taking the max of the | |||
1074 | // leading one bits. | |||
1075 | MaxHighOnes = | |||
1076 | std::max(Known.countMinLeadingOnes(), Known2.countMinLeadingOnes()); | |||
1077 | // If either side is non-negative, the result is non-negative. | |||
1078 | else if (Known.isNonNegative() || Known2.isNonNegative()) | |||
1079 | MaxHighZeros = 1; | |||
1080 | } else if (SPF == SPF_SMIN) { | |||
1081 | // If both sides are non-negative, the result is non-negative. | |||
1082 | if (Known.isNonNegative() && Known2.isNonNegative()) | |||
1083 | // We can derive an upper bound on the result by taking the max of the | |||
1084 | // leading zero bits. | |||
1085 | MaxHighZeros = std::max(Known.countMinLeadingZeros(), | |||
1086 | Known2.countMinLeadingZeros()); | |||
1087 | // If either side is negative, the result is negative. | |||
1088 | else if (Known.isNegative() || Known2.isNegative()) | |||
1089 | MaxHighOnes = 1; | |||
1090 | } else if (SPF == SPF_UMAX) { | |||
1091 | // We can derive a lower bound on the result by taking the max of the | |||
1092 | // leading one bits. | |||
1093 | MaxHighOnes = | |||
1094 | std::max(Known.countMinLeadingOnes(), Known2.countMinLeadingOnes()); | |||
1095 | } else if (SPF == SPF_UMIN) { | |||
1096 | // We can derive an upper bound on the result by taking the max of the | |||
1097 | // leading zero bits. | |||
1098 | MaxHighZeros = | |||
1099 | std::max(Known.countMinLeadingZeros(), Known2.countMinLeadingZeros()); | |||
1100 | } else if (SPF == SPF_ABS) { | |||
1101 | // RHS from matchSelectPattern returns the negation part of abs pattern. | |||
1102 | // If the negate has an NSW flag we can assume the sign bit of the result | |||
1103 | // will be 0 because that makes abs(INT_MIN) undefined. | |||
1104 | if (match(RHS, m_Neg(m_Specific(LHS))) && | |||
1105 | Q.IIQ.hasNoSignedWrap(cast<Instruction>(RHS))) | |||
1106 | MaxHighZeros = 1; | |||
1107 | } | |||
1108 | ||||
1109 | // Only known if known in both the LHS and RHS. | |||
1110 | Known.One &= Known2.One; | |||
1111 | Known.Zero &= Known2.Zero; | |||
1112 | if (MaxHighOnes > 0) | |||
1113 | Known.One.setHighBits(MaxHighOnes); | |||
1114 | if (MaxHighZeros > 0) | |||
1115 | Known.Zero.setHighBits(MaxHighZeros); | |||
1116 | break; | |||
1117 | } | |||
1118 | case Instruction::FPTrunc: | |||
1119 | case Instruction::FPExt: | |||
1120 | case Instruction::FPToUI: | |||
1121 | case Instruction::FPToSI: | |||
1122 | case Instruction::SIToFP: | |||
1123 | case Instruction::UIToFP: | |||
1124 | break; // Can't work with floating point. | |||
1125 | case Instruction::PtrToInt: | |||
1126 | case Instruction::IntToPtr: | |||
1127 | // Fall through and handle them the same as zext/trunc. | |||
1128 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
1129 | case Instruction::ZExt: | |||
1130 | case Instruction::Trunc: { | |||
1131 | Type *SrcTy = I->getOperand(0)->getType(); | |||
1132 | ||||
1133 | unsigned SrcBitWidth; | |||
1134 | // Note that we handle pointer operands here because of inttoptr/ptrtoint | |||
1135 | // which fall through here. | |||
1136 | Type *ScalarTy = SrcTy->getScalarType(); | |||
1137 | SrcBitWidth = ScalarTy->isPointerTy() ? | |||
1138 | Q.DL.getIndexTypeSizeInBits(ScalarTy) : | |||
1139 | Q.DL.getTypeSizeInBits(ScalarTy); | |||
1140 | ||||
1141 | assert(SrcBitWidth && "SrcBitWidth can't be zero")((SrcBitWidth && "SrcBitWidth can't be zero") ? static_cast <void> (0) : __assert_fail ("SrcBitWidth && \"SrcBitWidth can't be zero\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1141, __PRETTY_FUNCTION__)); | |||
1142 | Known = Known.zextOrTrunc(SrcBitWidth, false); | |||
1143 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1144 | Known = Known.zextOrTrunc(BitWidth, true /* ExtendedBitsAreKnownZero */); | |||
1145 | break; | |||
1146 | } | |||
1147 | case Instruction::BitCast: { | |||
1148 | Type *SrcTy = I->getOperand(0)->getType(); | |||
1149 | if (SrcTy->isIntOrPtrTy() && | |||
1150 | // TODO: For now, not handling conversions like: | |||
1151 | // (bitcast i64 %x to <2 x i32>) | |||
1152 | !I->getType()->isVectorTy()) { | |||
1153 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1154 | break; | |||
1155 | } | |||
1156 | break; | |||
1157 | } | |||
1158 | case Instruction::SExt: { | |||
1159 | // Compute the bits in the result that are not present in the input. | |||
1160 | unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits(); | |||
1161 | ||||
1162 | Known = Known.trunc(SrcBitWidth); | |||
1163 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1164 | // If the sign bit of the input is known set or clear, then we know the | |||
1165 | // top bits of the result. | |||
1166 | Known = Known.sext(BitWidth); | |||
1167 | break; | |||
1168 | } | |||
1169 | case Instruction::Shl: { | |||
1170 | // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0 | |||
1171 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1172 | auto KZF = [NSW](const APInt &KnownZero, unsigned ShiftAmt) { | |||
1173 | APInt KZResult = KnownZero << ShiftAmt; | |||
1174 | KZResult.setLowBits(ShiftAmt); // Low bits known 0. | |||
1175 | // If this shift has "nsw" keyword, then the result is either a poison | |||
1176 | // value or has the same sign bit as the first operand. | |||
1177 | if (NSW && KnownZero.isSignBitSet()) | |||
1178 | KZResult.setSignBit(); | |||
1179 | return KZResult; | |||
1180 | }; | |||
1181 | ||||
1182 | auto KOF = [NSW](const APInt &KnownOne, unsigned ShiftAmt) { | |||
1183 | APInt KOResult = KnownOne << ShiftAmt; | |||
1184 | if (NSW && KnownOne.isSignBitSet()) | |||
1185 | KOResult.setSignBit(); | |||
1186 | return KOResult; | |||
1187 | }; | |||
1188 | ||||
1189 | computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF); | |||
1190 | break; | |||
1191 | } | |||
1192 | case Instruction::LShr: { | |||
1193 | // (lshr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 | |||
1194 | auto KZF = [](const APInt &KnownZero, unsigned ShiftAmt) { | |||
1195 | APInt KZResult = KnownZero.lshr(ShiftAmt); | |||
1196 | // High bits known zero. | |||
1197 | KZResult.setHighBits(ShiftAmt); | |||
1198 | return KZResult; | |||
1199 | }; | |||
1200 | ||||
1201 | auto KOF = [](const APInt &KnownOne, unsigned ShiftAmt) { | |||
1202 | return KnownOne.lshr(ShiftAmt); | |||
1203 | }; | |||
1204 | ||||
1205 | computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF); | |||
1206 | break; | |||
1207 | } | |||
1208 | case Instruction::AShr: { | |||
1209 | // (ashr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 | |||
1210 | auto KZF = [](const APInt &KnownZero, unsigned ShiftAmt) { | |||
1211 | return KnownZero.ashr(ShiftAmt); | |||
1212 | }; | |||
1213 | ||||
1214 | auto KOF = [](const APInt &KnownOne, unsigned ShiftAmt) { | |||
1215 | return KnownOne.ashr(ShiftAmt); | |||
1216 | }; | |||
1217 | ||||
1218 | computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF); | |||
1219 | break; | |||
1220 | } | |||
1221 | case Instruction::Sub: { | |||
1222 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1223 | computeKnownBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW, | |||
1224 | Known, Known2, Depth, Q); | |||
1225 | break; | |||
1226 | } | |||
1227 | case Instruction::Add: { | |||
1228 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); | |||
1229 | computeKnownBitsAddSub(true, I->getOperand(0), I->getOperand(1), NSW, | |||
1230 | Known, Known2, Depth, Q); | |||
1231 | break; | |||
1232 | } | |||
1233 | case Instruction::SRem: | |||
1234 | if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { | |||
1235 | APInt RA = Rem->getValue().abs(); | |||
1236 | if (RA.isPowerOf2()) { | |||
1237 | APInt LowBits = RA - 1; | |||
1238 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1239 | ||||
1240 | // The low bits of the first operand are unchanged by the srem. | |||
1241 | Known.Zero = Known2.Zero & LowBits; | |||
1242 | Known.One = Known2.One & LowBits; | |||
1243 | ||||
1244 | // If the first operand is non-negative or has all low bits zero, then | |||
1245 | // the upper bits are all zero. | |||
1246 | if (Known2.isNonNegative() || LowBits.isSubsetOf(Known2.Zero)) | |||
1247 | Known.Zero |= ~LowBits; | |||
1248 | ||||
1249 | // If the first operand is negative and not all low bits are zero, then | |||
1250 | // the upper bits are all one. | |||
1251 | if (Known2.isNegative() && LowBits.intersects(Known2.One)) | |||
1252 | Known.One |= ~LowBits; | |||
1253 | ||||
1254 | assert((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?")(((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?" ) ? static_cast<void> (0) : __assert_fail ("(Known.Zero & Known.One) == 0 && \"Bits known to be one AND zero?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1254, __PRETTY_FUNCTION__)); | |||
1255 | break; | |||
1256 | } | |||
1257 | } | |||
1258 | ||||
1259 | // The sign bit is the LHS's sign bit, except when the result of the | |||
1260 | // remainder is zero. | |||
1261 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1262 | // If it's known zero, our sign bit is also zero. | |||
1263 | if (Known2.isNonNegative()) | |||
1264 | Known.makeNonNegative(); | |||
1265 | ||||
1266 | break; | |||
1267 | case Instruction::URem: { | |||
1268 | if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { | |||
1269 | const APInt &RA = Rem->getValue(); | |||
1270 | if (RA.isPowerOf2()) { | |||
1271 | APInt LowBits = (RA - 1); | |||
1272 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1273 | Known.Zero |= ~LowBits; | |||
1274 | Known.One &= LowBits; | |||
1275 | break; | |||
1276 | } | |||
1277 | } | |||
1278 | ||||
1279 | // Since the result is less than or equal to either operand, any leading | |||
1280 | // zero bits in either operand must also exist in the result. | |||
1281 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1282 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1283 | ||||
1284 | unsigned Leaders = | |||
1285 | std::max(Known.countMinLeadingZeros(), Known2.countMinLeadingZeros()); | |||
1286 | Known.resetAll(); | |||
1287 | Known.Zero.setHighBits(Leaders); | |||
1288 | break; | |||
1289 | } | |||
1290 | ||||
1291 | case Instruction::Alloca: { | |||
1292 | const AllocaInst *AI = cast<AllocaInst>(I); | |||
1293 | unsigned Align = AI->getAlignment(); | |||
1294 | if (Align == 0) | |||
1295 | Align = Q.DL.getABITypeAlignment(AI->getAllocatedType()); | |||
1296 | ||||
1297 | if (Align > 0) | |||
1298 | Known.Zero.setLowBits(countTrailingZeros(Align)); | |||
1299 | break; | |||
1300 | } | |||
1301 | case Instruction::GetElementPtr: { | |||
1302 | // Analyze all of the subscripts of this getelementptr instruction | |||
1303 | // to determine if we can prove known low zero bits. | |||
1304 | KnownBits LocalKnown(BitWidth); | |||
1305 | computeKnownBits(I->getOperand(0), LocalKnown, Depth + 1, Q); | |||
1306 | unsigned TrailZ = LocalKnown.countMinTrailingZeros(); | |||
1307 | ||||
1308 | gep_type_iterator GTI = gep_type_begin(I); | |||
1309 | for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) { | |||
1310 | Value *Index = I->getOperand(i); | |||
1311 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
1312 | // Handle struct member offset arithmetic. | |||
1313 | ||||
1314 | // Handle case when index is vector zeroinitializer | |||
1315 | Constant *CIndex = cast<Constant>(Index); | |||
1316 | if (CIndex->isZeroValue()) | |||
1317 | continue; | |||
1318 | ||||
1319 | if (CIndex->getType()->isVectorTy()) | |||
1320 | Index = CIndex->getSplatValue(); | |||
1321 | ||||
1322 | unsigned Idx = cast<ConstantInt>(Index)->getZExtValue(); | |||
1323 | const StructLayout *SL = Q.DL.getStructLayout(STy); | |||
1324 | uint64_t Offset = SL->getElementOffset(Idx); | |||
1325 | TrailZ = std::min<unsigned>(TrailZ, | |||
1326 | countTrailingZeros(Offset)); | |||
1327 | } else { | |||
1328 | // Handle array index arithmetic. | |||
1329 | Type *IndexedTy = GTI.getIndexedType(); | |||
1330 | if (!IndexedTy->isSized()) { | |||
1331 | TrailZ = 0; | |||
1332 | break; | |||
1333 | } | |||
1334 | unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits(); | |||
1335 | uint64_t TypeSize = Q.DL.getTypeAllocSize(IndexedTy); | |||
1336 | LocalKnown.Zero = LocalKnown.One = APInt(GEPOpiBits, 0); | |||
1337 | computeKnownBits(Index, LocalKnown, Depth + 1, Q); | |||
1338 | TrailZ = std::min(TrailZ, | |||
1339 | unsigned(countTrailingZeros(TypeSize) + | |||
1340 | LocalKnown.countMinTrailingZeros())); | |||
1341 | } | |||
1342 | } | |||
1343 | ||||
1344 | Known.Zero.setLowBits(TrailZ); | |||
1345 | break; | |||
1346 | } | |||
1347 | case Instruction::PHI: { | |||
1348 | const PHINode *P = cast<PHINode>(I); | |||
1349 | // Handle the case of a simple two-predecessor recurrence PHI. | |||
1350 | // There's a lot more that could theoretically be done here, but | |||
1351 | // this is sufficient to catch some interesting cases. | |||
1352 | if (P->getNumIncomingValues() == 2) { | |||
1353 | for (unsigned i = 0; i != 2; ++i) { | |||
1354 | Value *L = P->getIncomingValue(i); | |||
1355 | Value *R = P->getIncomingValue(!i); | |||
1356 | Operator *LU = dyn_cast<Operator>(L); | |||
1357 | if (!LU) | |||
1358 | continue; | |||
1359 | unsigned Opcode = LU->getOpcode(); | |||
1360 | // Check for operations that have the property that if | |||
1361 | // both their operands have low zero bits, the result | |||
1362 | // will have low zero bits. | |||
1363 | if (Opcode == Instruction::Add || | |||
1364 | Opcode == Instruction::Sub || | |||
1365 | Opcode == Instruction::And || | |||
1366 | Opcode == Instruction::Or || | |||
1367 | Opcode == Instruction::Mul) { | |||
1368 | Value *LL = LU->getOperand(0); | |||
1369 | Value *LR = LU->getOperand(1); | |||
1370 | // Find a recurrence. | |||
1371 | if (LL == I) | |||
1372 | L = LR; | |||
1373 | else if (LR == I) | |||
1374 | L = LL; | |||
1375 | else | |||
1376 | continue; // Check for recurrence with L and R flipped. | |||
1377 | // Ok, we have a PHI of the form L op= R. Check for low | |||
1378 | // zero bits. | |||
1379 | computeKnownBits(R, Known2, Depth + 1, Q); | |||
1380 | ||||
1381 | // We need to take the minimum number of known bits | |||
1382 | KnownBits Known3(Known); | |||
1383 | computeKnownBits(L, Known3, Depth + 1, Q); | |||
1384 | ||||
1385 | Known.Zero.setLowBits(std::min(Known2.countMinTrailingZeros(), | |||
1386 | Known3.countMinTrailingZeros())); | |||
1387 | ||||
1388 | auto *OverflowOp = dyn_cast<OverflowingBinaryOperator>(LU); | |||
1389 | if (OverflowOp && Q.IIQ.hasNoSignedWrap(OverflowOp)) { | |||
1390 | // If initial value of recurrence is nonnegative, and we are adding | |||
1391 | // a nonnegative number with nsw, the result can only be nonnegative | |||
1392 | // or poison value regardless of the number of times we execute the | |||
1393 | // add in phi recurrence. If initial value is negative and we are | |||
1394 | // adding a negative number with nsw, the result can only be | |||
1395 | // negative or poison value. Similar arguments apply to sub and mul. | |||
1396 | // | |||
1397 | // (add non-negative, non-negative) --> non-negative | |||
1398 | // (add negative, negative) --> negative | |||
1399 | if (Opcode == Instruction::Add) { | |||
1400 | if (Known2.isNonNegative() && Known3.isNonNegative()) | |||
1401 | Known.makeNonNegative(); | |||
1402 | else if (Known2.isNegative() && Known3.isNegative()) | |||
1403 | Known.makeNegative(); | |||
1404 | } | |||
1405 | ||||
1406 | // (sub nsw non-negative, negative) --> non-negative | |||
1407 | // (sub nsw negative, non-negative) --> negative | |||
1408 | else if (Opcode == Instruction::Sub && LL == I) { | |||
1409 | if (Known2.isNonNegative() && Known3.isNegative()) | |||
1410 | Known.makeNonNegative(); | |||
1411 | else if (Known2.isNegative() && Known3.isNonNegative()) | |||
1412 | Known.makeNegative(); | |||
1413 | } | |||
1414 | ||||
1415 | // (mul nsw non-negative, non-negative) --> non-negative | |||
1416 | else if (Opcode == Instruction::Mul && Known2.isNonNegative() && | |||
1417 | Known3.isNonNegative()) | |||
1418 | Known.makeNonNegative(); | |||
1419 | } | |||
1420 | ||||
1421 | break; | |||
1422 | } | |||
1423 | } | |||
1424 | } | |||
1425 | ||||
1426 | // Unreachable blocks may have zero-operand PHI nodes. | |||
1427 | if (P->getNumIncomingValues() == 0) | |||
1428 | break; | |||
1429 | ||||
1430 | // Otherwise take the unions of the known bit sets of the operands, | |||
1431 | // taking conservative care to avoid excessive recursion. | |||
1432 | if (Depth < MaxDepth - 1 && !Known.Zero && !Known.One) { | |||
1433 | // Skip if every incoming value references to ourself. | |||
1434 | if (dyn_cast_or_null<UndefValue>(P->hasConstantValue())) | |||
1435 | break; | |||
1436 | ||||
1437 | Known.Zero.setAllBits(); | |||
1438 | Known.One.setAllBits(); | |||
1439 | for (Value *IncValue : P->incoming_values()) { | |||
1440 | // Skip direct self references. | |||
1441 | if (IncValue == P) continue; | |||
1442 | ||||
1443 | Known2 = KnownBits(BitWidth); | |||
1444 | // Recurse, but cap the recursion to one level, because we don't | |||
1445 | // want to waste time spinning around in loops. | |||
1446 | computeKnownBits(IncValue, Known2, MaxDepth - 1, Q); | |||
1447 | Known.Zero &= Known2.Zero; | |||
1448 | Known.One &= Known2.One; | |||
1449 | // If all bits have been ruled out, there's no need to check | |||
1450 | // more operands. | |||
1451 | if (!Known.Zero && !Known.One) | |||
1452 | break; | |||
1453 | } | |||
1454 | } | |||
1455 | break; | |||
1456 | } | |||
1457 | case Instruction::Call: | |||
1458 | case Instruction::Invoke: | |||
1459 | // If range metadata is attached to this call, set known bits from that, | |||
1460 | // and then intersect with known bits based on other properties of the | |||
1461 | // function. | |||
1462 | if (MDNode *MD = | |||
1463 | Q.IIQ.getMetadata(cast<Instruction>(I), LLVMContext::MD_range)) | |||
1464 | computeKnownBitsFromRangeMetadata(*MD, Known); | |||
1465 | if (const Value *RV = ImmutableCallSite(I).getReturnedArgOperand()) { | |||
1466 | computeKnownBits(RV, Known2, Depth + 1, Q); | |||
1467 | Known.Zero |= Known2.Zero; | |||
1468 | Known.One |= Known2.One; | |||
1469 | } | |||
1470 | if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { | |||
1471 | switch (II->getIntrinsicID()) { | |||
1472 | default: break; | |||
1473 | case Intrinsic::bitreverse: | |||
1474 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1475 | Known.Zero |= Known2.Zero.reverseBits(); | |||
1476 | Known.One |= Known2.One.reverseBits(); | |||
1477 | break; | |||
1478 | case Intrinsic::bswap: | |||
1479 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1480 | Known.Zero |= Known2.Zero.byteSwap(); | |||
1481 | Known.One |= Known2.One.byteSwap(); | |||
1482 | break; | |||
1483 | case Intrinsic::ctlz: { | |||
1484 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1485 | // If we have a known 1, its position is our upper bound. | |||
1486 | unsigned PossibleLZ = Known2.One.countLeadingZeros(); | |||
1487 | // If this call is undefined for 0, the result will be less than 2^n. | |||
1488 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) | |||
1489 | PossibleLZ = std::min(PossibleLZ, BitWidth - 1); | |||
1490 | unsigned LowBits = Log2_32(PossibleLZ)+1; | |||
1491 | Known.Zero.setBitsFrom(LowBits); | |||
1492 | break; | |||
1493 | } | |||
1494 | case Intrinsic::cttz: { | |||
1495 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1496 | // If we have a known 1, its position is our upper bound. | |||
1497 | unsigned PossibleTZ = Known2.One.countTrailingZeros(); | |||
1498 | // If this call is undefined for 0, the result will be less than 2^n. | |||
1499 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) | |||
1500 | PossibleTZ = std::min(PossibleTZ, BitWidth - 1); | |||
1501 | unsigned LowBits = Log2_32(PossibleTZ)+1; | |||
1502 | Known.Zero.setBitsFrom(LowBits); | |||
1503 | break; | |||
1504 | } | |||
1505 | case Intrinsic::ctpop: { | |||
1506 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1507 | // We can bound the space the count needs. Also, bits known to be zero | |||
1508 | // can't contribute to the population. | |||
1509 | unsigned BitsPossiblySet = Known2.countMaxPopulation(); | |||
1510 | unsigned LowBits = Log2_32(BitsPossiblySet)+1; | |||
1511 | Known.Zero.setBitsFrom(LowBits); | |||
1512 | // TODO: we could bound KnownOne using the lower bound on the number | |||
1513 | // of bits which might be set provided by popcnt KnownOne2. | |||
1514 | break; | |||
1515 | } | |||
1516 | case Intrinsic::fshr: | |||
1517 | case Intrinsic::fshl: { | |||
1518 | const APInt *SA; | |||
1519 | if (!match(I->getOperand(2), m_APInt(SA))) | |||
1520 | break; | |||
1521 | ||||
1522 | // Normalize to funnel shift left. | |||
1523 | uint64_t ShiftAmt = SA->urem(BitWidth); | |||
1524 | if (II->getIntrinsicID() == Intrinsic::fshr) | |||
1525 | ShiftAmt = BitWidth - ShiftAmt; | |||
1526 | ||||
1527 | KnownBits Known3(Known); | |||
1528 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); | |||
1529 | computeKnownBits(I->getOperand(1), Known3, Depth + 1, Q); | |||
1530 | ||||
1531 | Known.Zero = | |||
1532 | Known2.Zero.shl(ShiftAmt) | Known3.Zero.lshr(BitWidth - ShiftAmt); | |||
1533 | Known.One = | |||
1534 | Known2.One.shl(ShiftAmt) | Known3.One.lshr(BitWidth - ShiftAmt); | |||
1535 | break; | |||
1536 | } | |||
1537 | case Intrinsic::uadd_sat: | |||
1538 | case Intrinsic::usub_sat: { | |||
1539 | bool IsAdd = II->getIntrinsicID() == Intrinsic::uadd_sat; | |||
1540 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1541 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); | |||
1542 | ||||
1543 | // Add: Leading ones of either operand are preserved. | |||
1544 | // Sub: Leading zeros of LHS and leading ones of RHS are preserved | |||
1545 | // as leading zeros in the result. | |||
1546 | unsigned LeadingKnown; | |||
1547 | if (IsAdd) | |||
1548 | LeadingKnown = std::max(Known.countMinLeadingOnes(), | |||
1549 | Known2.countMinLeadingOnes()); | |||
1550 | else | |||
1551 | LeadingKnown = std::max(Known.countMinLeadingZeros(), | |||
1552 | Known2.countMinLeadingOnes()); | |||
1553 | ||||
1554 | Known = KnownBits::computeForAddSub( | |||
1555 | IsAdd, /* NSW */ false, Known, Known2); | |||
1556 | ||||
1557 | // We select between the operation result and all-ones/zero | |||
1558 | // respectively, so we can preserve known ones/zeros. | |||
1559 | if (IsAdd) { | |||
1560 | Known.One.setHighBits(LeadingKnown); | |||
1561 | Known.Zero.clearAllBits(); | |||
1562 | } else { | |||
1563 | Known.Zero.setHighBits(LeadingKnown); | |||
1564 | Known.One.clearAllBits(); | |||
1565 | } | |||
1566 | break; | |||
1567 | } | |||
1568 | case Intrinsic::x86_sse42_crc32_64_64: | |||
1569 | Known.Zero.setBitsFrom(32); | |||
1570 | break; | |||
1571 | } | |||
1572 | } | |||
1573 | break; | |||
1574 | case Instruction::ExtractElement: | |||
1575 | // Look through extract element. At the moment we keep this simple and skip | |||
1576 | // tracking the specific element. But at least we might find information | |||
1577 | // valid for all elements of the vector (for example if vector is sign | |||
1578 | // extended, shifted, etc). | |||
1579 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); | |||
1580 | break; | |||
1581 | case Instruction::ExtractValue: | |||
1582 | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I->getOperand(0))) { | |||
1583 | const ExtractValueInst *EVI = cast<ExtractValueInst>(I); | |||
1584 | if (EVI->getNumIndices() != 1) break; | |||
1585 | if (EVI->getIndices()[0] == 0) { | |||
1586 | switch (II->getIntrinsicID()) { | |||
1587 | default: break; | |||
1588 | case Intrinsic::uadd_with_overflow: | |||
1589 | case Intrinsic::sadd_with_overflow: | |||
1590 | computeKnownBitsAddSub(true, II->getArgOperand(0), | |||
1591 | II->getArgOperand(1), false, Known, Known2, | |||
1592 | Depth, Q); | |||
1593 | break; | |||
1594 | case Intrinsic::usub_with_overflow: | |||
1595 | case Intrinsic::ssub_with_overflow: | |||
1596 | computeKnownBitsAddSub(false, II->getArgOperand(0), | |||
1597 | II->getArgOperand(1), false, Known, Known2, | |||
1598 | Depth, Q); | |||
1599 | break; | |||
1600 | case Intrinsic::umul_with_overflow: | |||
1601 | case Intrinsic::smul_with_overflow: | |||
1602 | computeKnownBitsMul(II->getArgOperand(0), II->getArgOperand(1), false, | |||
1603 | Known, Known2, Depth, Q); | |||
1604 | break; | |||
1605 | } | |||
1606 | } | |||
1607 | } | |||
1608 | } | |||
1609 | } | |||
1610 | ||||
1611 | /// Determine which bits of V are known to be either zero or one and return | |||
1612 | /// them. | |||
1613 | KnownBits computeKnownBits(const Value *V, unsigned Depth, const Query &Q) { | |||
1614 | KnownBits Known(getBitWidth(V->getType(), Q.DL)); | |||
1615 | computeKnownBits(V, Known, Depth, Q); | |||
1616 | return Known; | |||
1617 | } | |||
1618 | ||||
1619 | /// Determine which bits of V are known to be either zero or one and return | |||
1620 | /// them in the Known bit set. | |||
1621 | /// | |||
1622 | /// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that | |||
1623 | /// we cannot optimize based on the assumption that it is zero without changing | |||
1624 | /// it to be an explicit zero. If we don't change it to zero, other code could | |||
1625 | /// optimized based on the contradictory assumption that it is non-zero. | |||
1626 | /// Because instcombine aggressively folds operations with undef args anyway, | |||
1627 | /// this won't lose us code quality. | |||
1628 | /// | |||
1629 | /// This function is defined on values with integer type, values with pointer | |||
1630 | /// type, and vectors of integers. In the case | |||
1631 | /// where V is a vector, known zero, and known one values are the | |||
1632 | /// same width as the vector element, and the bit is set only if it is true | |||
1633 | /// for all of the elements in the vector. | |||
1634 | void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth, | |||
1635 | const Query &Q) { | |||
1636 | assert(V && "No Value?")((V && "No Value?") ? static_cast<void> (0) : __assert_fail ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1636, __PRETTY_FUNCTION__)); | |||
1637 | assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast <void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1637, __PRETTY_FUNCTION__)); | |||
1638 | unsigned BitWidth = Known.getBitWidth(); | |||
1639 | ||||
1640 | assert((V->getType()->isIntOrIntVectorTy(BitWidth) ||(((V->getType()->isIntOrIntVectorTy(BitWidth) || V-> getType()->isPtrOrPtrVectorTy()) && "Not integer or pointer type!" ) ? static_cast<void> (0) : __assert_fail ("(V->getType()->isIntOrIntVectorTy(BitWidth) || V->getType()->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1642, __PRETTY_FUNCTION__)) | |||
1641 | V->getType()->isPtrOrPtrVectorTy()) &&(((V->getType()->isIntOrIntVectorTy(BitWidth) || V-> getType()->isPtrOrPtrVectorTy()) && "Not integer or pointer type!" ) ? static_cast<void> (0) : __assert_fail ("(V->getType()->isIntOrIntVectorTy(BitWidth) || V->getType()->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1642, __PRETTY_FUNCTION__)) | |||
1642 | "Not integer or pointer type!")(((V->getType()->isIntOrIntVectorTy(BitWidth) || V-> getType()->isPtrOrPtrVectorTy()) && "Not integer or pointer type!" ) ? static_cast<void> (0) : __assert_fail ("(V->getType()->isIntOrIntVectorTy(BitWidth) || V->getType()->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1642, __PRETTY_FUNCTION__)); | |||
1643 | ||||
1644 | Type *ScalarTy = V->getType()->getScalarType(); | |||
1645 | unsigned ExpectedWidth = ScalarTy->isPointerTy() ? | |||
1646 | Q.DL.getIndexTypeSizeInBits(ScalarTy) : Q.DL.getTypeSizeInBits(ScalarTy); | |||
1647 | assert(ExpectedWidth == BitWidth && "V and Known should have same BitWidth")((ExpectedWidth == BitWidth && "V and Known should have same BitWidth" ) ? static_cast<void> (0) : __assert_fail ("ExpectedWidth == BitWidth && \"V and Known should have same BitWidth\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1647, __PRETTY_FUNCTION__)); | |||
1648 | (void)BitWidth; | |||
1649 | (void)ExpectedWidth; | |||
1650 | ||||
1651 | const APInt *C; | |||
1652 | if (match(V, m_APInt(C))) { | |||
1653 | // We know all of the bits for a scalar constant or a splat vector constant! | |||
1654 | Known.One = *C; | |||
1655 | Known.Zero = ~Known.One; | |||
1656 | return; | |||
1657 | } | |||
1658 | // Null and aggregate-zero are all-zeros. | |||
1659 | if (isa<ConstantPointerNull>(V) || isa<ConstantAggregateZero>(V)) { | |||
1660 | Known.setAllZero(); | |||
1661 | return; | |||
1662 | } | |||
1663 | // Handle a constant vector by taking the intersection of the known bits of | |||
1664 | // each element. | |||
1665 | if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(V)) { | |||
1666 | // We know that CDS must be a vector of integers. Take the intersection of | |||
1667 | // each element. | |||
1668 | Known.Zero.setAllBits(); Known.One.setAllBits(); | |||
1669 | for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { | |||
1670 | APInt Elt = CDS->getElementAsAPInt(i); | |||
1671 | Known.Zero &= ~Elt; | |||
1672 | Known.One &= Elt; | |||
1673 | } | |||
1674 | return; | |||
1675 | } | |||
1676 | ||||
1677 | if (const auto *CV = dyn_cast<ConstantVector>(V)) { | |||
1678 | // We know that CV must be a vector of integers. Take the intersection of | |||
1679 | // each element. | |||
1680 | Known.Zero.setAllBits(); Known.One.setAllBits(); | |||
1681 | for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) { | |||
1682 | Constant *Element = CV->getAggregateElement(i); | |||
1683 | auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element); | |||
1684 | if (!ElementCI) { | |||
1685 | Known.resetAll(); | |||
1686 | return; | |||
1687 | } | |||
1688 | const APInt &Elt = ElementCI->getValue(); | |||
1689 | Known.Zero &= ~Elt; | |||
1690 | Known.One &= Elt; | |||
1691 | } | |||
1692 | return; | |||
1693 | } | |||
1694 | ||||
1695 | // Start out not knowing anything. | |||
1696 | Known.resetAll(); | |||
1697 | ||||
1698 | // We can't imply anything about undefs. | |||
1699 | if (isa<UndefValue>(V)) | |||
1700 | return; | |||
1701 | ||||
1702 | // There's no point in looking through other users of ConstantData for | |||
1703 | // assumptions. Confirm that we've handled them all. | |||
1704 | assert(!isa<ConstantData>(V) && "Unhandled constant data!")((!isa<ConstantData>(V) && "Unhandled constant data!" ) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantData>(V) && \"Unhandled constant data!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1704, __PRETTY_FUNCTION__)); | |||
1705 | ||||
1706 | // Limit search depth. | |||
1707 | // All recursive calls that increase depth must come after this. | |||
1708 | if (Depth == MaxDepth) | |||
1709 | return; | |||
1710 | ||||
1711 | // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has | |||
1712 | // the bits of its aliasee. | |||
1713 | if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { | |||
1714 | if (!GA->isInterposable()) | |||
1715 | computeKnownBits(GA->getAliasee(), Known, Depth + 1, Q); | |||
1716 | return; | |||
1717 | } | |||
1718 | ||||
1719 | if (const Operator *I = dyn_cast<Operator>(V)) | |||
1720 | computeKnownBitsFromOperator(I, Known, Depth, Q); | |||
1721 | ||||
1722 | // Aligned pointers have trailing zeros - refine Known.Zero set | |||
1723 | if (V->getType()->isPointerTy()) { | |||
1724 | unsigned Align = V->getPointerAlignment(Q.DL); | |||
1725 | if (Align) | |||
1726 | Known.Zero.setLowBits(countTrailingZeros(Align)); | |||
1727 | } | |||
1728 | ||||
1729 | // computeKnownBitsFromAssume strictly refines Known. | |||
1730 | // Therefore, we run them after computeKnownBitsFromOperator. | |||
1731 | ||||
1732 | // Check whether a nearby assume intrinsic can determine some known bits. | |||
1733 | computeKnownBitsFromAssume(V, Known, Depth, Q); | |||
1734 | ||||
1735 | assert((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?")(((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?" ) ? static_cast<void> (0) : __assert_fail ("(Known.Zero & Known.One) == 0 && \"Bits known to be one AND zero?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1735, __PRETTY_FUNCTION__)); | |||
1736 | } | |||
1737 | ||||
1738 | /// Return true if the given value is known to have exactly one | |||
1739 | /// bit set when defined. For vectors return true if every element is known to | |||
1740 | /// be a power of two when defined. Supports values with integer or pointer | |||
1741 | /// types and vectors of integers. | |||
1742 | bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, | |||
1743 | const Query &Q) { | |||
1744 | assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast <void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1744, __PRETTY_FUNCTION__)); | |||
1745 | ||||
1746 | // Attempt to match against constants. | |||
1747 | if (OrZero && match(V, m_Power2OrZero())) | |||
1748 | return true; | |||
1749 | if (match(V, m_Power2())) | |||
1750 | return true; | |||
1751 | ||||
1752 | // 1 << X is clearly a power of two if the one is not shifted off the end. If | |||
1753 | // it is shifted off the end then the result is undefined. | |||
1754 | if (match(V, m_Shl(m_One(), m_Value()))) | |||
1755 | return true; | |||
1756 | ||||
1757 | // (signmask) >>l X is clearly a power of two if the one is not shifted off | |||
1758 | // the bottom. If it is shifted off the bottom then the result is undefined. | |||
1759 | if (match(V, m_LShr(m_SignMask(), m_Value()))) | |||
1760 | return true; | |||
1761 | ||||
1762 | // The remaining tests are all recursive, so bail out if we hit the limit. | |||
1763 | if (Depth++ == MaxDepth) | |||
1764 | return false; | |||
1765 | ||||
1766 | Value *X = nullptr, *Y = nullptr; | |||
1767 | // A shift left or a logical shift right of a power of two is a power of two | |||
1768 | // or zero. | |||
1769 | if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) || | |||
1770 | match(V, m_LShr(m_Value(X), m_Value())))) | |||
1771 | return isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q); | |||
1772 | ||||
1773 | if (const ZExtInst *ZI = dyn_cast<ZExtInst>(V)) | |||
1774 | return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth, Q); | |||
1775 | ||||
1776 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) | |||
1777 | return isKnownToBeAPowerOfTwo(SI->getTrueValue(), OrZero, Depth, Q) && | |||
1778 | isKnownToBeAPowerOfTwo(SI->getFalseValue(), OrZero, Depth, Q); | |||
1779 | ||||
1780 | if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) { | |||
1781 | // A power of two and'd with anything is a power of two or zero. | |||
1782 | if (isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q) || | |||
1783 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, Depth, Q)) | |||
1784 | return true; | |||
1785 | // X & (-X) is always a power of two or zero. | |||
1786 | if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X)))) | |||
1787 | return true; | |||
1788 | return false; | |||
1789 | } | |||
1790 | ||||
1791 | // Adding a power-of-two or zero to the same power-of-two or zero yields | |||
1792 | // either the original power-of-two, a larger power-of-two or zero. | |||
1793 | if (match(V, m_Add(m_Value(X), m_Value(Y)))) { | |||
1794 | const OverflowingBinaryOperator *VOBO = cast<OverflowingBinaryOperator>(V); | |||
1795 | if (OrZero || Q.IIQ.hasNoUnsignedWrap(VOBO) || | |||
1796 | Q.IIQ.hasNoSignedWrap(VOBO)) { | |||
1797 | if (match(X, m_And(m_Specific(Y), m_Value())) || | |||
1798 | match(X, m_And(m_Value(), m_Specific(Y)))) | |||
1799 | if (isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q)) | |||
1800 | return true; | |||
1801 | if (match(Y, m_And(m_Specific(X), m_Value())) || | |||
1802 | match(Y, m_And(m_Value(), m_Specific(X)))) | |||
1803 | if (isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q)) | |||
1804 | return true; | |||
1805 | ||||
1806 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); | |||
1807 | KnownBits LHSBits(BitWidth); | |||
1808 | computeKnownBits(X, LHSBits, Depth, Q); | |||
1809 | ||||
1810 | KnownBits RHSBits(BitWidth); | |||
1811 | computeKnownBits(Y, RHSBits, Depth, Q); | |||
1812 | // If i8 V is a power of two or zero: | |||
1813 | // ZeroBits: 1 1 1 0 1 1 1 1 | |||
1814 | // ~ZeroBits: 0 0 0 1 0 0 0 0 | |||
1815 | if ((~(LHSBits.Zero & RHSBits.Zero)).isPowerOf2()) | |||
1816 | // If OrZero isn't set, we cannot give back a zero result. | |||
1817 | // Make sure either the LHS or RHS has a bit set. | |||
1818 | if (OrZero || RHSBits.One.getBoolValue() || LHSBits.One.getBoolValue()) | |||
1819 | return true; | |||
1820 | } | |||
1821 | } | |||
1822 | ||||
1823 | // An exact divide or right shift can only shift off zero bits, so the result | |||
1824 | // is a power of two only if the first operand is a power of two and not | |||
1825 | // copying a sign bit (sdiv int_min, 2). | |||
1826 | if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) || | |||
1827 | match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) { | |||
1828 | return isKnownToBeAPowerOfTwo(cast<Operator>(V)->getOperand(0), OrZero, | |||
1829 | Depth, Q); | |||
1830 | } | |||
1831 | ||||
1832 | return false; | |||
1833 | } | |||
1834 | ||||
1835 | /// Test whether a GEP's result is known to be non-null. | |||
1836 | /// | |||
1837 | /// Uses properties inherent in a GEP to try to determine whether it is known | |||
1838 | /// to be non-null. | |||
1839 | /// | |||
1840 | /// Currently this routine does not support vector GEPs. | |||
1841 | static bool isGEPKnownNonNull(const GEPOperator *GEP, unsigned Depth, | |||
1842 | const Query &Q) { | |||
1843 | const Function *F = nullptr; | |||
1844 | if (const Instruction *I = dyn_cast<Instruction>(GEP)) | |||
1845 | F = I->getFunction(); | |||
1846 | ||||
1847 | if (!GEP->isInBounds() || | |||
1848 | NullPointerIsDefined(F, GEP->getPointerAddressSpace())) | |||
1849 | return false; | |||
1850 | ||||
1851 | // FIXME: Support vector-GEPs. | |||
1852 | assert(GEP->getType()->isPointerTy() && "We only support plain pointer GEP")((GEP->getType()->isPointerTy() && "We only support plain pointer GEP" ) ? static_cast<void> (0) : __assert_fail ("GEP->getType()->isPointerTy() && \"We only support plain pointer GEP\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1852, __PRETTY_FUNCTION__)); | |||
1853 | ||||
1854 | // If the base pointer is non-null, we cannot walk to a null address with an | |||
1855 | // inbounds GEP in address space zero. | |||
1856 | if (isKnownNonZero(GEP->getPointerOperand(), Depth, Q)) | |||
1857 | return true; | |||
1858 | ||||
1859 | // Walk the GEP operands and see if any operand introduces a non-zero offset. | |||
1860 | // If so, then the GEP cannot produce a null pointer, as doing so would | |||
1861 | // inherently violate the inbounds contract within address space zero. | |||
1862 | for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP); | |||
1863 | GTI != GTE; ++GTI) { | |||
1864 | // Struct types are easy -- they must always be indexed by a constant. | |||
1865 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
1866 | ConstantInt *OpC = cast<ConstantInt>(GTI.getOperand()); | |||
1867 | unsigned ElementIdx = OpC->getZExtValue(); | |||
1868 | const StructLayout *SL = Q.DL.getStructLayout(STy); | |||
1869 | uint64_t ElementOffset = SL->getElementOffset(ElementIdx); | |||
1870 | if (ElementOffset > 0) | |||
1871 | return true; | |||
1872 | continue; | |||
1873 | } | |||
1874 | ||||
1875 | // If we have a zero-sized type, the index doesn't matter. Keep looping. | |||
1876 | if (Q.DL.getTypeAllocSize(GTI.getIndexedType()) == 0) | |||
1877 | continue; | |||
1878 | ||||
1879 | // Fast path the constant operand case both for efficiency and so we don't | |||
1880 | // increment Depth when just zipping down an all-constant GEP. | |||
1881 | if (ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand())) { | |||
1882 | if (!OpC->isZero()) | |||
1883 | return true; | |||
1884 | continue; | |||
1885 | } | |||
1886 | ||||
1887 | // We post-increment Depth here because while isKnownNonZero increments it | |||
1888 | // as well, when we pop back up that increment won't persist. We don't want | |||
1889 | // to recurse 10k times just because we have 10k GEP operands. We don't | |||
1890 | // bail completely out because we want to handle constant GEPs regardless | |||
1891 | // of depth. | |||
1892 | if (Depth++ >= MaxDepth) | |||
1893 | continue; | |||
1894 | ||||
1895 | if (isKnownNonZero(GTI.getOperand(), Depth, Q)) | |||
1896 | return true; | |||
1897 | } | |||
1898 | ||||
1899 | return false; | |||
1900 | } | |||
1901 | ||||
1902 | static bool isKnownNonNullFromDominatingCondition(const Value *V, | |||
1903 | const Instruction *CtxI, | |||
1904 | const DominatorTree *DT) { | |||
1905 | assert(V->getType()->isPointerTy() && "V must be pointer type")((V->getType()->isPointerTy() && "V must be pointer type" ) ? static_cast<void> (0) : __assert_fail ("V->getType()->isPointerTy() && \"V must be pointer type\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1905, __PRETTY_FUNCTION__)); | |||
1906 | assert(!isa<ConstantData>(V) && "Did not expect ConstantPointerNull")((!isa<ConstantData>(V) && "Did not expect ConstantPointerNull" ) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantData>(V) && \"Did not expect ConstantPointerNull\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1906, __PRETTY_FUNCTION__)); | |||
1907 | ||||
1908 | if (!CtxI || !DT) | |||
1909 | return false; | |||
1910 | ||||
1911 | unsigned NumUsesExplored = 0; | |||
1912 | for (auto *U : V->users()) { | |||
1913 | // Avoid massive lists | |||
1914 | if (NumUsesExplored >= DomConditionsMaxUses) | |||
1915 | break; | |||
1916 | NumUsesExplored++; | |||
1917 | ||||
1918 | // If the value is used as an argument to a call or invoke, then argument | |||
1919 | // attributes may provide an answer about null-ness. | |||
1920 | if (auto CS = ImmutableCallSite(U)) | |||
1921 | if (auto *CalledFunc = CS.getCalledFunction()) | |||
1922 | for (const Argument &Arg : CalledFunc->args()) | |||
1923 | if (CS.getArgOperand(Arg.getArgNo()) == V && | |||
1924 | Arg.hasNonNullAttr() && DT->dominates(CS.getInstruction(), CtxI)) | |||
1925 | return true; | |||
1926 | ||||
1927 | // Consider only compare instructions uniquely controlling a branch | |||
1928 | CmpInst::Predicate Pred; | |||
1929 | if (!match(const_cast<User *>(U), | |||
1930 | m_c_ICmp(Pred, m_Specific(V), m_Zero())) || | |||
1931 | (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE)) | |||
1932 | continue; | |||
1933 | ||||
1934 | SmallVector<const User *, 4> WorkList; | |||
1935 | SmallPtrSet<const User *, 4> Visited; | |||
1936 | for (auto *CmpU : U->users()) { | |||
1937 | assert(WorkList.empty() && "Should be!")((WorkList.empty() && "Should be!") ? static_cast< void> (0) : __assert_fail ("WorkList.empty() && \"Should be!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1937, __PRETTY_FUNCTION__)); | |||
1938 | if (Visited.insert(CmpU).second) | |||
1939 | WorkList.push_back(CmpU); | |||
1940 | ||||
1941 | while (!WorkList.empty()) { | |||
1942 | auto *Curr = WorkList.pop_back_val(); | |||
1943 | ||||
1944 | // If a user is an AND, add all its users to the work list. We only | |||
1945 | // propagate "pred != null" condition through AND because it is only | |||
1946 | // correct to assume that all conditions of AND are met in true branch. | |||
1947 | // TODO: Support similar logic of OR and EQ predicate? | |||
1948 | if (Pred == ICmpInst::ICMP_NE) | |||
1949 | if (auto *BO = dyn_cast<BinaryOperator>(Curr)) | |||
1950 | if (BO->getOpcode() == Instruction::And) { | |||
1951 | for (auto *BOU : BO->users()) | |||
1952 | if (Visited.insert(BOU).second) | |||
1953 | WorkList.push_back(BOU); | |||
1954 | continue; | |||
1955 | } | |||
1956 | ||||
1957 | if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) { | |||
1958 | assert(BI->isConditional() && "uses a comparison!")((BI->isConditional() && "uses a comparison!") ? static_cast <void> (0) : __assert_fail ("BI->isConditional() && \"uses a comparison!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1958, __PRETTY_FUNCTION__)); | |||
1959 | ||||
1960 | BasicBlock *NonNullSuccessor = | |||
1961 | BI->getSuccessor(Pred == ICmpInst::ICMP_EQ ? 1 : 0); | |||
1962 | BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor); | |||
1963 | if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent())) | |||
1964 | return true; | |||
1965 | } else if (Pred == ICmpInst::ICMP_NE && isGuard(Curr) && | |||
1966 | DT->dominates(cast<Instruction>(Curr), CtxI)) { | |||
1967 | return true; | |||
1968 | } | |||
1969 | } | |||
1970 | } | |||
1971 | } | |||
1972 | ||||
1973 | return false; | |||
1974 | } | |||
1975 | ||||
1976 | /// Does the 'Range' metadata (which must be a valid MD_range operand list) | |||
1977 | /// ensure that the value it's attached to is never Value? 'RangeType' is | |||
1978 | /// is the type of the value described by the range. | |||
1979 | static bool rangeMetadataExcludesValue(const MDNode* Ranges, const APInt& Value) { | |||
1980 | const unsigned NumRanges = Ranges->getNumOperands() / 2; | |||
1981 | assert(NumRanges >= 1)((NumRanges >= 1) ? static_cast<void> (0) : __assert_fail ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 1981, __PRETTY_FUNCTION__)); | |||
1982 | for (unsigned i = 0; i < NumRanges; ++i) { | |||
1983 | ConstantInt *Lower = | |||
1984 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 0)); | |||
1985 | ConstantInt *Upper = | |||
1986 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 1)); | |||
1987 | ConstantRange Range(Lower->getValue(), Upper->getValue()); | |||
1988 | if (Range.contains(Value)) | |||
1989 | return false; | |||
1990 | } | |||
1991 | return true; | |||
1992 | } | |||
1993 | ||||
1994 | /// Return true if the given value is known to be non-zero when defined. For | |||
1995 | /// vectors, return true if every element is known to be non-zero when | |||
1996 | /// defined. For pointers, if the context instruction and dominator tree are | |||
1997 | /// specified, perform context-sensitive analysis and return true if the | |||
1998 | /// pointer couldn't possibly be null at the specified instruction. | |||
1999 | /// Supports values with integer or pointer type and vectors of integers. | |||
2000 | bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q) { | |||
2001 | if (auto *C = dyn_cast<Constant>(V)) { | |||
2002 | if (C->isNullValue()) | |||
2003 | return false; | |||
2004 | if (isa<ConstantInt>(C)) | |||
2005 | // Must be non-zero due to null test above. | |||
2006 | return true; | |||
2007 | ||||
2008 | if (auto *CE = dyn_cast<ConstantExpr>(C)) { | |||
2009 | // See the comment for IntToPtr/PtrToInt instructions below. | |||
2010 | if (CE->getOpcode() == Instruction::IntToPtr || | |||
2011 | CE->getOpcode() == Instruction::PtrToInt) | |||
2012 | if (Q.DL.getTypeSizeInBits(CE->getOperand(0)->getType()) <= | |||
2013 | Q.DL.getTypeSizeInBits(CE->getType())) | |||
2014 | return isKnownNonZero(CE->getOperand(0), Depth, Q); | |||
2015 | } | |||
2016 | ||||
2017 | // For constant vectors, check that all elements are undefined or known | |||
2018 | // non-zero to determine that the whole vector is known non-zero. | |||
2019 | if (auto *VecTy = dyn_cast<VectorType>(C->getType())) { | |||
2020 | for (unsigned i = 0, e = VecTy->getNumElements(); i != e; ++i) { | |||
2021 | Constant *Elt = C->getAggregateElement(i); | |||
2022 | if (!Elt || Elt->isNullValue()) | |||
2023 | return false; | |||
2024 | if (!isa<UndefValue>(Elt) && !isa<ConstantInt>(Elt)) | |||
2025 | return false; | |||
2026 | } | |||
2027 | return true; | |||
2028 | } | |||
2029 | ||||
2030 | // A global variable in address space 0 is non null unless extern weak | |||
2031 | // or an absolute symbol reference. Other address spaces may have null as a | |||
2032 | // valid address for a global, so we can't assume anything. | |||
2033 | if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) { | |||
2034 | if (!GV->isAbsoluteSymbolRef() && !GV->hasExternalWeakLinkage() && | |||
2035 | GV->getType()->getAddressSpace() == 0) | |||
2036 | return true; | |||
2037 | } else | |||
2038 | return false; | |||
2039 | } | |||
2040 | ||||
2041 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
2042 | if (MDNode *Ranges = Q.IIQ.getMetadata(I, LLVMContext::MD_range)) { | |||
2043 | // If the possible ranges don't contain zero, then the value is | |||
2044 | // definitely non-zero. | |||
2045 | if (auto *Ty = dyn_cast<IntegerType>(V->getType())) { | |||
2046 | const APInt ZeroValue(Ty->getBitWidth(), 0); | |||
2047 | if (rangeMetadataExcludesValue(Ranges, ZeroValue)) | |||
2048 | return true; | |||
2049 | } | |||
2050 | } | |||
2051 | } | |||
2052 | ||||
2053 | // Some of the tests below are recursive, so bail out if we hit the limit. | |||
2054 | if (Depth++ >= MaxDepth) | |||
2055 | return false; | |||
2056 | ||||
2057 | // Check for pointer simplifications. | |||
2058 | if (V->getType()->isPointerTy()) { | |||
2059 | // Alloca never returns null, malloc might. | |||
2060 | if (isa<AllocaInst>(V) && Q.DL.getAllocaAddrSpace() == 0) | |||
2061 | return true; | |||
2062 | ||||
2063 | // A byval, inalloca, or nonnull argument is never null. | |||
2064 | if (const Argument *A = dyn_cast<Argument>(V)) | |||
2065 | if (A->hasByValOrInAllocaAttr() || A->hasNonNullAttr()) | |||
2066 | return true; | |||
2067 | ||||
2068 | // A Load tagged with nonnull metadata is never null. | |||
2069 | if (const LoadInst *LI = dyn_cast<LoadInst>(V)) | |||
2070 | if (Q.IIQ.getMetadata(LI, LLVMContext::MD_nonnull)) | |||
2071 | return true; | |||
2072 | ||||
2073 | if (const auto *Call = dyn_cast<CallBase>(V)) { | |||
2074 | if (Call->isReturnNonNull()) | |||
2075 | return true; | |||
2076 | if (const auto *RP = getArgumentAliasingToReturnedPointer(Call, true)) | |||
2077 | return isKnownNonZero(RP, Depth, Q); | |||
2078 | } | |||
2079 | } | |||
2080 | ||||
2081 | ||||
2082 | // Check for recursive pointer simplifications. | |||
2083 | if (V->getType()->isPointerTy()) { | |||
2084 | if (isKnownNonNullFromDominatingCondition(V, Q.CxtI, Q.DT)) | |||
2085 | return true; | |||
2086 | ||||
2087 | // Look through bitcast operations, GEPs, and int2ptr instructions as they | |||
2088 | // do not alter the value, or at least not the nullness property of the | |||
2089 | // value, e.g., int2ptr is allowed to zero/sign extend the value. | |||
2090 | // | |||
2091 | // Note that we have to take special care to avoid looking through | |||
2092 | // truncating casts, e.g., int2ptr/ptr2int with appropriate sizes, as well | |||
2093 | // as casts that can alter the value, e.g., AddrSpaceCasts. | |||
2094 | if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) | |||
2095 | if (isGEPKnownNonNull(GEP, Depth, Q)) | |||
2096 | return true; | |||
2097 | ||||
2098 | if (auto *BCO = dyn_cast<BitCastOperator>(V)) | |||
2099 | return isKnownNonZero(BCO->getOperand(0), Depth, Q); | |||
2100 | ||||
2101 | if (auto *I2P = dyn_cast<IntToPtrInst>(V)) | |||
2102 | if (Q.DL.getTypeSizeInBits(I2P->getSrcTy()) <= | |||
2103 | Q.DL.getTypeSizeInBits(I2P->getDestTy())) | |||
2104 | return isKnownNonZero(I2P->getOperand(0), Depth, Q); | |||
2105 | } | |||
2106 | ||||
2107 | // Similar to int2ptr above, we can look through ptr2int here if the cast | |||
2108 | // is a no-op or an extend and not a truncate. | |||
2109 | if (auto *P2I = dyn_cast<PtrToIntInst>(V)) | |||
2110 | if (Q.DL.getTypeSizeInBits(P2I->getSrcTy()) <= | |||
2111 | Q.DL.getTypeSizeInBits(P2I->getDestTy())) | |||
2112 | return isKnownNonZero(P2I->getOperand(0), Depth, Q); | |||
2113 | ||||
2114 | unsigned BitWidth = getBitWidth(V->getType()->getScalarType(), Q.DL); | |||
2115 | ||||
2116 | // X | Y != 0 if X != 0 or Y != 0. | |||
2117 | Value *X = nullptr, *Y = nullptr; | |||
2118 | if (match(V, m_Or(m_Value(X), m_Value(Y)))) | |||
2119 | return isKnownNonZero(X, Depth, Q) || isKnownNonZero(Y, Depth, Q); | |||
2120 | ||||
2121 | // ext X != 0 if X != 0. | |||
2122 | if (isa<SExtInst>(V) || isa<ZExtInst>(V)) | |||
2123 | return isKnownNonZero(cast<Instruction>(V)->getOperand(0), Depth, Q); | |||
2124 | ||||
2125 | // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined | |||
2126 | // if the lowest bit is shifted off the end. | |||
2127 | if (match(V, m_Shl(m_Value(X), m_Value(Y)))) { | |||
2128 | // shl nuw can't remove any non-zero bits. | |||
2129 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); | |||
2130 | if (Q.IIQ.hasNoUnsignedWrap(BO)) | |||
2131 | return isKnownNonZero(X, Depth, Q); | |||
2132 | ||||
2133 | KnownBits Known(BitWidth); | |||
2134 | computeKnownBits(X, Known, Depth, Q); | |||
2135 | if (Known.One[0]) | |||
2136 | return true; | |||
2137 | } | |||
2138 | // shr X, Y != 0 if X is negative. Note that the value of the shift is not | |||
2139 | // defined if the sign bit is shifted off the end. | |||
2140 | else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) { | |||
2141 | // shr exact can only shift out zero bits. | |||
2142 | const PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V); | |||
2143 | if (BO->isExact()) | |||
2144 | return isKnownNonZero(X, Depth, Q); | |||
2145 | ||||
2146 | KnownBits Known = computeKnownBits(X, Depth, Q); | |||
2147 | if (Known.isNegative()) | |||
2148 | return true; | |||
2149 | ||||
2150 | // If the shifter operand is a constant, and all of the bits shifted | |||
2151 | // out are known to be zero, and X is known non-zero then at least one | |||
2152 | // non-zero bit must remain. | |||
2153 | if (ConstantInt *Shift = dyn_cast<ConstantInt>(Y)) { | |||
2154 | auto ShiftVal = Shift->getLimitedValue(BitWidth - 1); | |||
2155 | // Is there a known one in the portion not shifted out? | |||
2156 | if (Known.countMaxLeadingZeros() < BitWidth - ShiftVal) | |||
2157 | return true; | |||
2158 | // Are all the bits to be shifted out known zero? | |||
2159 | if (Known.countMinTrailingZeros() >= ShiftVal) | |||
2160 | return isKnownNonZero(X, Depth, Q); | |||
2161 | } | |||
2162 | } | |||
2163 | // div exact can only produce a zero if the dividend is zero. | |||
2164 | else if (match(V, m_Exact(m_IDiv(m_Value(X), m_Value())))) { | |||
2165 | return isKnownNonZero(X, Depth, Q); | |||
2166 | } | |||
2167 | // X + Y. | |||
2168 | else if (match(V, m_Add(m_Value(X), m_Value(Y)))) { | |||
2169 | KnownBits XKnown = computeKnownBits(X, Depth, Q); | |||
2170 | KnownBits YKnown = computeKnownBits(Y, Depth, Q); | |||
2171 | ||||
2172 | // If X and Y are both non-negative (as signed values) then their sum is not | |||
2173 | // zero unless both X and Y are zero. | |||
2174 | if (XKnown.isNonNegative() && YKnown.isNonNegative()) | |||
2175 | if (isKnownNonZero(X, Depth, Q) || isKnownNonZero(Y, Depth, Q)) | |||
2176 | return true; | |||
2177 | ||||
2178 | // If X and Y are both negative (as signed values) then their sum is not | |||
2179 | // zero unless both X and Y equal INT_MIN. | |||
2180 | if (XKnown.isNegative() && YKnown.isNegative()) { | |||
2181 | APInt Mask = APInt::getSignedMaxValue(BitWidth); | |||
2182 | // The sign bit of X is set. If some other bit is set then X is not equal | |||
2183 | // to INT_MIN. | |||
2184 | if (XKnown.One.intersects(Mask)) | |||
2185 | return true; | |||
2186 | // The sign bit of Y is set. If some other bit is set then Y is not equal | |||
2187 | // to INT_MIN. | |||
2188 | if (YKnown.One.intersects(Mask)) | |||
2189 | return true; | |||
2190 | } | |||
2191 | ||||
2192 | // The sum of a non-negative number and a power of two is not zero. | |||
2193 | if (XKnown.isNonNegative() && | |||
2194 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ false, Depth, Q)) | |||
2195 | return true; | |||
2196 | if (YKnown.isNonNegative() && | |||
2197 | isKnownToBeAPowerOfTwo(X, /*OrZero*/ false, Depth, Q)) | |||
2198 | return true; | |||
2199 | } | |||
2200 | // X * Y. | |||
2201 | else if (match(V, m_Mul(m_Value(X), m_Value(Y)))) { | |||
2202 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); | |||
2203 | // If X and Y are non-zero then so is X * Y as long as the multiplication | |||
2204 | // does not overflow. | |||
2205 | if ((Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO)) && | |||
2206 | isKnownNonZero(X, Depth, Q) && isKnownNonZero(Y, Depth, Q)) | |||
2207 | return true; | |||
2208 | } | |||
2209 | // (C ? X : Y) != 0 if X != 0 and Y != 0. | |||
2210 | else if (const SelectInst *SI = dyn_cast<SelectInst>(V)) { | |||
2211 | if (isKnownNonZero(SI->getTrueValue(), Depth, Q) && | |||
2212 | isKnownNonZero(SI->getFalseValue(), Depth, Q)) | |||
2213 | return true; | |||
2214 | } | |||
2215 | // PHI | |||
2216 | else if (const PHINode *PN = dyn_cast<PHINode>(V)) { | |||
2217 | // Try and detect a recurrence that monotonically increases from a | |||
2218 | // starting value, as these are common as induction variables. | |||
2219 | if (PN->getNumIncomingValues() == 2) { | |||
2220 | Value *Start = PN->getIncomingValue(0); | |||
2221 | Value *Induction = PN->getIncomingValue(1); | |||
2222 | if (isa<ConstantInt>(Induction) && !isa<ConstantInt>(Start)) | |||
2223 | std::swap(Start, Induction); | |||
2224 | if (ConstantInt *C = dyn_cast<ConstantInt>(Start)) { | |||
2225 | if (!C->isZero() && !C->isNegative()) { | |||
2226 | ConstantInt *X; | |||
2227 | if (Q.IIQ.UseInstrInfo && | |||
2228 | (match(Induction, m_NSWAdd(m_Specific(PN), m_ConstantInt(X))) || | |||
2229 | match(Induction, m_NUWAdd(m_Specific(PN), m_ConstantInt(X)))) && | |||
2230 | !X->isNegative()) | |||
2231 | return true; | |||
2232 | } | |||
2233 | } | |||
2234 | } | |||
2235 | // Check if all incoming values are non-zero constant. | |||
2236 | bool AllNonZeroConstants = llvm::all_of(PN->operands(), [](Value *V) { | |||
2237 | return isa<ConstantInt>(V) && !cast<ConstantInt>(V)->isZero(); | |||
2238 | }); | |||
2239 | if (AllNonZeroConstants) | |||
2240 | return true; | |||
2241 | } | |||
2242 | ||||
2243 | KnownBits Known(BitWidth); | |||
2244 | computeKnownBits(V, Known, Depth, Q); | |||
2245 | return Known.One != 0; | |||
2246 | } | |||
2247 | ||||
2248 | /// Return true if V2 == V1 + X, where X is known non-zero. | |||
2249 | static bool isAddOfNonZero(const Value *V1, const Value *V2, const Query &Q) { | |||
2250 | const BinaryOperator *BO = dyn_cast<BinaryOperator>(V1); | |||
2251 | if (!BO || BO->getOpcode() != Instruction::Add) | |||
2252 | return false; | |||
2253 | Value *Op = nullptr; | |||
2254 | if (V2 == BO->getOperand(0)) | |||
2255 | Op = BO->getOperand(1); | |||
2256 | else if (V2 == BO->getOperand(1)) | |||
2257 | Op = BO->getOperand(0); | |||
2258 | else | |||
2259 | return false; | |||
2260 | return isKnownNonZero(Op, 0, Q); | |||
2261 | } | |||
2262 | ||||
2263 | /// Return true if it is known that V1 != V2. | |||
2264 | static bool isKnownNonEqual(const Value *V1, const Value *V2, const Query &Q) { | |||
2265 | if (V1 == V2) | |||
2266 | return false; | |||
2267 | if (V1->getType() != V2->getType()) | |||
2268 | // We can't look through casts yet. | |||
2269 | return false; | |||
2270 | if (isAddOfNonZero(V1, V2, Q) || isAddOfNonZero(V2, V1, Q)) | |||
2271 | return true; | |||
2272 | ||||
2273 | if (V1->getType()->isIntOrIntVectorTy()) { | |||
2274 | // Are any known bits in V1 contradictory to known bits in V2? If V1 | |||
2275 | // has a known zero where V2 has a known one, they must not be equal. | |||
2276 | KnownBits Known1 = computeKnownBits(V1, 0, Q); | |||
2277 | KnownBits Known2 = computeKnownBits(V2, 0, Q); | |||
2278 | ||||
2279 | if (Known1.Zero.intersects(Known2.One) || | |||
2280 | Known2.Zero.intersects(Known1.One)) | |||
2281 | return true; | |||
2282 | } | |||
2283 | return false; | |||
2284 | } | |||
2285 | ||||
2286 | /// Return true if 'V & Mask' is known to be zero. We use this predicate to | |||
2287 | /// simplify operations downstream. Mask is known to be zero for bits that V | |||
2288 | /// cannot have. | |||
2289 | /// | |||
2290 | /// This function is defined on values with integer type, values with pointer | |||
2291 | /// type, and vectors of integers. In the case | |||
2292 | /// where V is a vector, the mask, known zero, and known one values are the | |||
2293 | /// same width as the vector element, and the bit is set only if it is true | |||
2294 | /// for all of the elements in the vector. | |||
2295 | bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, | |||
2296 | const Query &Q) { | |||
2297 | KnownBits Known(Mask.getBitWidth()); | |||
2298 | computeKnownBits(V, Known, Depth, Q); | |||
2299 | return Mask.isSubsetOf(Known.Zero); | |||
2300 | } | |||
2301 | ||||
2302 | // Match a signed min+max clamp pattern like smax(smin(In, CHigh), CLow). | |||
2303 | // Returns the input and lower/upper bounds. | |||
2304 | static bool isSignedMinMaxClamp(const Value *Select, const Value *&In, | |||
2305 | const APInt *&CLow, const APInt *&CHigh) { | |||
2306 | assert(isa<Operator>(Select) &&((isa<Operator>(Select) && cast<Operator> (Select)->getOpcode() == Instruction::Select && "Input should be a Select!" ) ? static_cast<void> (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2308, __PRETTY_FUNCTION__)) | |||
2307 | cast<Operator>(Select)->getOpcode() == Instruction::Select &&((isa<Operator>(Select) && cast<Operator> (Select)->getOpcode() == Instruction::Select && "Input should be a Select!" ) ? static_cast<void> (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2308, __PRETTY_FUNCTION__)) | |||
2308 | "Input should be a Select!")((isa<Operator>(Select) && cast<Operator> (Select)->getOpcode() == Instruction::Select && "Input should be a Select!" ) ? static_cast<void> (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2308, __PRETTY_FUNCTION__)); | |||
2309 | ||||
2310 | const Value *LHS, *RHS, *LHS2, *RHS2; | |||
2311 | SelectPatternFlavor SPF = matchSelectPattern(Select, LHS, RHS).Flavor; | |||
2312 | if (SPF != SPF_SMAX && SPF != SPF_SMIN) | |||
2313 | return false; | |||
2314 | ||||
2315 | if (!match(RHS, m_APInt(CLow))) | |||
2316 | return false; | |||
2317 | ||||
2318 | SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor; | |||
2319 | if (getInverseMinMaxFlavor(SPF) != SPF2) | |||
2320 | return false; | |||
2321 | ||||
2322 | if (!match(RHS2, m_APInt(CHigh))) | |||
2323 | return false; | |||
2324 | ||||
2325 | if (SPF == SPF_SMIN) | |||
2326 | std::swap(CLow, CHigh); | |||
2327 | ||||
2328 | In = LHS2; | |||
2329 | return CLow->sle(*CHigh); | |||
2330 | } | |||
2331 | ||||
2332 | /// For vector constants, loop over the elements and find the constant with the | |||
2333 | /// minimum number of sign bits. Return 0 if the value is not a vector constant | |||
2334 | /// or if any element was not analyzed; otherwise, return the count for the | |||
2335 | /// element with the minimum number of sign bits. | |||
2336 | static unsigned computeNumSignBitsVectorConstant(const Value *V, | |||
2337 | unsigned TyBits) { | |||
2338 | const auto *CV = dyn_cast<Constant>(V); | |||
2339 | if (!CV || !CV->getType()->isVectorTy()) | |||
2340 | return 0; | |||
2341 | ||||
2342 | unsigned MinSignBits = TyBits; | |||
2343 | unsigned NumElts = CV->getType()->getVectorNumElements(); | |||
2344 | for (unsigned i = 0; i != NumElts; ++i) { | |||
2345 | // If we find a non-ConstantInt, bail out. | |||
2346 | auto *Elt = dyn_cast_or_null<ConstantInt>(CV->getAggregateElement(i)); | |||
2347 | if (!Elt) | |||
2348 | return 0; | |||
2349 | ||||
2350 | MinSignBits = std::min(MinSignBits, Elt->getValue().getNumSignBits()); | |||
2351 | } | |||
2352 | ||||
2353 | return MinSignBits; | |||
2354 | } | |||
2355 | ||||
2356 | static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth, | |||
2357 | const Query &Q); | |||
2358 | ||||
2359 | static unsigned ComputeNumSignBits(const Value *V, unsigned Depth, | |||
2360 | const Query &Q) { | |||
2361 | unsigned Result = ComputeNumSignBitsImpl(V, Depth, Q); | |||
2362 | assert(Result > 0 && "At least one sign bit needs to be present!")((Result > 0 && "At least one sign bit needs to be present!" ) ? static_cast<void> (0) : __assert_fail ("Result > 0 && \"At least one sign bit needs to be present!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2362, __PRETTY_FUNCTION__)); | |||
2363 | return Result; | |||
2364 | } | |||
2365 | ||||
2366 | /// Return the number of times the sign bit of the register is replicated into | |||
2367 | /// the other bits. We know that at least 1 bit is always equal to the sign bit | |||
2368 | /// (itself), but other cases can give us information. For example, immediately | |||
2369 | /// after an "ashr X, 2", we know that the top 3 bits are all equal to each | |||
2370 | /// other, so we return 3. For vectors, return the number of sign bits for the | |||
2371 | /// vector element with the minimum number of known sign bits. | |||
2372 | static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth, | |||
2373 | const Query &Q) { | |||
2374 | assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast <void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2374, __PRETTY_FUNCTION__)); | |||
2375 | ||||
2376 | // We return the minimum number of sign bits that are guaranteed to be present | |||
2377 | // in V, so for undef we have to conservatively return 1. We don't have the | |||
2378 | // same behavior for poison though -- that's a FIXME today. | |||
2379 | ||||
2380 | Type *ScalarTy = V->getType()->getScalarType(); | |||
2381 | unsigned TyBits = ScalarTy->isPointerTy() ? | |||
2382 | Q.DL.getIndexTypeSizeInBits(ScalarTy) : | |||
2383 | Q.DL.getTypeSizeInBits(ScalarTy); | |||
2384 | ||||
2385 | unsigned Tmp, Tmp2; | |||
2386 | unsigned FirstAnswer = 1; | |||
2387 | ||||
2388 | // Note that ConstantInt is handled by the general computeKnownBits case | |||
2389 | // below. | |||
2390 | ||||
2391 | if (Depth == MaxDepth) | |||
2392 | return 1; // Limit search depth. | |||
2393 | ||||
2394 | const Operator *U = dyn_cast<Operator>(V); | |||
2395 | switch (Operator::getOpcode(V)) { | |||
2396 | default: break; | |||
2397 | case Instruction::SExt: | |||
2398 | Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); | |||
2399 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q) + Tmp; | |||
2400 | ||||
2401 | case Instruction::SDiv: { | |||
2402 | const APInt *Denominator; | |||
2403 | // sdiv X, C -> adds log(C) sign bits. | |||
2404 | if (match(U->getOperand(1), m_APInt(Denominator))) { | |||
2405 | ||||
2406 | // Ignore non-positive denominator. | |||
2407 | if (!Denominator->isStrictlyPositive()) | |||
2408 | break; | |||
2409 | ||||
2410 | // Calculate the incoming numerator bits. | |||
2411 | unsigned NumBits = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2412 | ||||
2413 | // Add floor(log(C)) bits to the numerator bits. | |||
2414 | return std::min(TyBits, NumBits + Denominator->logBase2()); | |||
2415 | } | |||
2416 | break; | |||
2417 | } | |||
2418 | ||||
2419 | case Instruction::SRem: { | |||
2420 | const APInt *Denominator; | |||
2421 | // srem X, C -> we know that the result is within [-C+1,C) when C is a | |||
2422 | // positive constant. This let us put a lower bound on the number of sign | |||
2423 | // bits. | |||
2424 | if (match(U->getOperand(1), m_APInt(Denominator))) { | |||
2425 | ||||
2426 | // Ignore non-positive denominator. | |||
2427 | if (!Denominator->isStrictlyPositive()) | |||
2428 | break; | |||
2429 | ||||
2430 | // Calculate the incoming numerator bits. SRem by a positive constant | |||
2431 | // can't lower the number of sign bits. | |||
2432 | unsigned NumrBits = | |||
2433 | ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2434 | ||||
2435 | // Calculate the leading sign bit constraints by examining the | |||
2436 | // denominator. Given that the denominator is positive, there are two | |||
2437 | // cases: | |||
2438 | // | |||
2439 | // 1. the numerator is positive. The result range is [0,C) and [0,C) u< | |||
2440 | // (1 << ceilLogBase2(C)). | |||
2441 | // | |||
2442 | // 2. the numerator is negative. Then the result range is (-C,0] and | |||
2443 | // integers in (-C,0] are either 0 or >u (-1 << ceilLogBase2(C)). | |||
2444 | // | |||
2445 | // Thus a lower bound on the number of sign bits is `TyBits - | |||
2446 | // ceilLogBase2(C)`. | |||
2447 | ||||
2448 | unsigned ResBits = TyBits - Denominator->ceilLogBase2(); | |||
2449 | return std::max(NumrBits, ResBits); | |||
2450 | } | |||
2451 | break; | |||
2452 | } | |||
2453 | ||||
2454 | case Instruction::AShr: { | |||
2455 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2456 | // ashr X, C -> adds C sign bits. Vectors too. | |||
2457 | const APInt *ShAmt; | |||
2458 | if (match(U->getOperand(1), m_APInt(ShAmt))) { | |||
2459 | if (ShAmt->uge(TyBits)) | |||
2460 | break; // Bad shift. | |||
2461 | unsigned ShAmtLimited = ShAmt->getZExtValue(); | |||
2462 | Tmp += ShAmtLimited; | |||
2463 | if (Tmp > TyBits) Tmp = TyBits; | |||
2464 | } | |||
2465 | return Tmp; | |||
2466 | } | |||
2467 | case Instruction::Shl: { | |||
2468 | const APInt *ShAmt; | |||
2469 | if (match(U->getOperand(1), m_APInt(ShAmt))) { | |||
2470 | // shl destroys sign bits. | |||
2471 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2472 | if (ShAmt->uge(TyBits) || // Bad shift. | |||
2473 | ShAmt->uge(Tmp)) break; // Shifted all sign bits out. | |||
2474 | Tmp2 = ShAmt->getZExtValue(); | |||
2475 | return Tmp - Tmp2; | |||
2476 | } | |||
2477 | break; | |||
2478 | } | |||
2479 | case Instruction::And: | |||
2480 | case Instruction::Or: | |||
2481 | case Instruction::Xor: // NOT is handled here. | |||
2482 | // Logical binary ops preserve the number of sign bits at the worst. | |||
2483 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2484 | if (Tmp != 1) { | |||
2485 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
2486 | FirstAnswer = std::min(Tmp, Tmp2); | |||
2487 | // We computed what we know about the sign bits as our first | |||
2488 | // answer. Now proceed to the generic code that uses | |||
2489 | // computeKnownBits, and pick whichever answer is better. | |||
2490 | } | |||
2491 | break; | |||
2492 | ||||
2493 | case Instruction::Select: { | |||
2494 | // If we have a clamp pattern, we know that the number of sign bits will be | |||
2495 | // the minimum of the clamp min/max range. | |||
2496 | const Value *X; | |||
2497 | const APInt *CLow, *CHigh; | |||
2498 | if (isSignedMinMaxClamp(U, X, CLow, CHigh)) | |||
2499 | return std::min(CLow->getNumSignBits(), CHigh->getNumSignBits()); | |||
2500 | ||||
2501 | Tmp = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
2502 | if (Tmp == 1) break; | |||
2503 | Tmp2 = ComputeNumSignBits(U->getOperand(2), Depth + 1, Q); | |||
2504 | return std::min(Tmp, Tmp2); | |||
2505 | } | |||
2506 | ||||
2507 | case Instruction::Add: | |||
2508 | // Add can have at most one carry bit. Thus we know that the output | |||
2509 | // is, at worst, one more bit than the inputs. | |||
2510 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2511 | if (Tmp == 1) break; | |||
2512 | ||||
2513 | // Special case decrementing a value (ADD X, -1): | |||
2514 | if (const auto *CRHS = dyn_cast<Constant>(U->getOperand(1))) | |||
2515 | if (CRHS->isAllOnesValue()) { | |||
2516 | KnownBits Known(TyBits); | |||
2517 | computeKnownBits(U->getOperand(0), Known, Depth + 1, Q); | |||
2518 | ||||
2519 | // If the input is known to be 0 or 1, the output is 0/-1, which is all | |||
2520 | // sign bits set. | |||
2521 | if ((Known.Zero | 1).isAllOnesValue()) | |||
2522 | return TyBits; | |||
2523 | ||||
2524 | // If we are subtracting one from a positive number, there is no carry | |||
2525 | // out of the result. | |||
2526 | if (Known.isNonNegative()) | |||
2527 | return Tmp; | |||
2528 | } | |||
2529 | ||||
2530 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
2531 | if (Tmp2 == 1) break; | |||
2532 | return std::min(Tmp, Tmp2)-1; | |||
2533 | ||||
2534 | case Instruction::Sub: | |||
2535 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
2536 | if (Tmp2 == 1) break; | |||
2537 | ||||
2538 | // Handle NEG. | |||
2539 | if (const auto *CLHS = dyn_cast<Constant>(U->getOperand(0))) | |||
2540 | if (CLHS->isNullValue()) { | |||
2541 | KnownBits Known(TyBits); | |||
2542 | computeKnownBits(U->getOperand(1), Known, Depth + 1, Q); | |||
2543 | // If the input is known to be 0 or 1, the output is 0/-1, which is all | |||
2544 | // sign bits set. | |||
2545 | if ((Known.Zero | 1).isAllOnesValue()) | |||
2546 | return TyBits; | |||
2547 | ||||
2548 | // If the input is known to be positive (the sign bit is known clear), | |||
2549 | // the output of the NEG has the same number of sign bits as the input. | |||
2550 | if (Known.isNonNegative()) | |||
2551 | return Tmp2; | |||
2552 | ||||
2553 | // Otherwise, we treat this like a SUB. | |||
2554 | } | |||
2555 | ||||
2556 | // Sub can have at most one carry bit. Thus we know that the output | |||
2557 | // is, at worst, one more bit than the inputs. | |||
2558 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2559 | if (Tmp == 1) break; | |||
2560 | return std::min(Tmp, Tmp2)-1; | |||
2561 | ||||
2562 | case Instruction::Mul: { | |||
2563 | // The output of the Mul can be at most twice the valid bits in the inputs. | |||
2564 | unsigned SignBitsOp0 = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2565 | if (SignBitsOp0 == 1) break; | |||
2566 | unsigned SignBitsOp1 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); | |||
2567 | if (SignBitsOp1 == 1) break; | |||
2568 | unsigned OutValidBits = | |||
2569 | (TyBits - SignBitsOp0 + 1) + (TyBits - SignBitsOp1 + 1); | |||
2570 | return OutValidBits > TyBits ? 1 : TyBits - OutValidBits + 1; | |||
2571 | } | |||
2572 | ||||
2573 | case Instruction::PHI: { | |||
2574 | const PHINode *PN = cast<PHINode>(U); | |||
2575 | unsigned NumIncomingValues = PN->getNumIncomingValues(); | |||
2576 | // Don't analyze large in-degree PHIs. | |||
2577 | if (NumIncomingValues > 4) break; | |||
2578 | // Unreachable blocks may have zero-operand PHI nodes. | |||
2579 | if (NumIncomingValues == 0) break; | |||
2580 | ||||
2581 | // Take the minimum of all incoming values. This can't infinitely loop | |||
2582 | // because of our depth threshold. | |||
2583 | Tmp = ComputeNumSignBits(PN->getIncomingValue(0), Depth + 1, Q); | |||
2584 | for (unsigned i = 1, e = NumIncomingValues; i != e; ++i) { | |||
2585 | if (Tmp == 1) return Tmp; | |||
2586 | Tmp = std::min( | |||
2587 | Tmp, ComputeNumSignBits(PN->getIncomingValue(i), Depth + 1, Q)); | |||
2588 | } | |||
2589 | return Tmp; | |||
2590 | } | |||
2591 | ||||
2592 | case Instruction::Trunc: | |||
2593 | // FIXME: it's tricky to do anything useful for this, but it is an important | |||
2594 | // case for targets like X86. | |||
2595 | break; | |||
2596 | ||||
2597 | case Instruction::ExtractElement: | |||
2598 | // Look through extract element. At the moment we keep this simple and skip | |||
2599 | // tracking the specific element. But at least we might find information | |||
2600 | // valid for all elements of the vector (for example if vector is sign | |||
2601 | // extended, shifted, etc). | |||
2602 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); | |||
2603 | ||||
2604 | case Instruction::ShuffleVector: { | |||
2605 | // TODO: This is copied almost directly from the SelectionDAG version of | |||
2606 | // ComputeNumSignBits. It would be better if we could share common | |||
2607 | // code. If not, make sure that changes are translated to the DAG. | |||
2608 | ||||
2609 | // Collect the minimum number of sign bits that are shared by every vector | |||
2610 | // element referenced by the shuffle. | |||
2611 | auto *Shuf = cast<ShuffleVectorInst>(U); | |||
2612 | int NumElts = Shuf->getOperand(0)->getType()->getVectorNumElements(); | |||
2613 | int NumMaskElts = Shuf->getMask()->getType()->getVectorNumElements(); | |||
2614 | APInt DemandedLHS(NumElts, 0), DemandedRHS(NumElts, 0); | |||
2615 | for (int i = 0; i != NumMaskElts; ++i) { | |||
2616 | int M = Shuf->getMaskValue(i); | |||
2617 | assert(M < NumElts * 2 && "Invalid shuffle mask constant")((M < NumElts * 2 && "Invalid shuffle mask constant" ) ? static_cast<void> (0) : __assert_fail ("M < NumElts * 2 && \"Invalid shuffle mask constant\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2617, __PRETTY_FUNCTION__)); | |||
2618 | // For undef elements, we don't know anything about the common state of | |||
2619 | // the shuffle result. | |||
2620 | if (M == -1) | |||
2621 | return 1; | |||
2622 | if (M < NumElts) | |||
2623 | DemandedLHS.setBit(M % NumElts); | |||
2624 | else | |||
2625 | DemandedRHS.setBit(M % NumElts); | |||
2626 | } | |||
2627 | Tmp = std::numeric_limits<unsigned>::max(); | |||
2628 | if (!!DemandedLHS) | |||
2629 | Tmp = ComputeNumSignBits(Shuf->getOperand(0), Depth + 1, Q); | |||
2630 | if (!!DemandedRHS) { | |||
2631 | Tmp2 = ComputeNumSignBits(Shuf->getOperand(1), Depth + 1, Q); | |||
2632 | Tmp = std::min(Tmp, Tmp2); | |||
2633 | } | |||
2634 | // If we don't know anything, early out and try computeKnownBits fall-back. | |||
2635 | if (Tmp == 1) | |||
2636 | break; | |||
2637 | assert(Tmp <= V->getType()->getScalarSizeInBits() &&((Tmp <= V->getType()->getScalarSizeInBits() && "Failed to determine minimum sign bits") ? static_cast<void > (0) : __assert_fail ("Tmp <= V->getType()->getScalarSizeInBits() && \"Failed to determine minimum sign bits\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2638, __PRETTY_FUNCTION__)) | |||
2638 | "Failed to determine minimum sign bits")((Tmp <= V->getType()->getScalarSizeInBits() && "Failed to determine minimum sign bits") ? static_cast<void > (0) : __assert_fail ("Tmp <= V->getType()->getScalarSizeInBits() && \"Failed to determine minimum sign bits\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2638, __PRETTY_FUNCTION__)); | |||
2639 | return Tmp; | |||
2640 | } | |||
2641 | } | |||
2642 | ||||
2643 | // Finally, if we can prove that the top bits of the result are 0's or 1's, | |||
2644 | // use this information. | |||
2645 | ||||
2646 | // If we can examine all elements of a vector constant successfully, we're | |||
2647 | // done (we can't do any better than that). If not, keep trying. | |||
2648 | if (unsigned VecSignBits = computeNumSignBitsVectorConstant(V, TyBits)) | |||
2649 | return VecSignBits; | |||
2650 | ||||
2651 | KnownBits Known(TyBits); | |||
2652 | computeKnownBits(V, Known, Depth, Q); | |||
2653 | ||||
2654 | // If we know that the sign bit is either zero or one, determine the number of | |||
2655 | // identical bits in the top of the input value. | |||
2656 | return std::max(FirstAnswer, Known.countMinSignBits()); | |||
2657 | } | |||
2658 | ||||
2659 | /// This function computes the integer multiple of Base that equals V. | |||
2660 | /// If successful, it returns true and returns the multiple in | |||
2661 | /// Multiple. If unsuccessful, it returns false. It looks | |||
2662 | /// through SExt instructions only if LookThroughSExt is true. | |||
2663 | bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, | |||
2664 | bool LookThroughSExt, unsigned Depth) { | |||
2665 | const unsigned MaxDepth = 6; | |||
2666 | ||||
2667 | assert(V && "No Value?")((V && "No Value?") ? static_cast<void> (0) : __assert_fail ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2667, __PRETTY_FUNCTION__)); | |||
2668 | assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast <void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2668, __PRETTY_FUNCTION__)); | |||
2669 | assert(V->getType()->isIntegerTy() && "Not integer or pointer type!")((V->getType()->isIntegerTy() && "Not integer or pointer type!" ) ? static_cast<void> (0) : __assert_fail ("V->getType()->isIntegerTy() && \"Not integer or pointer type!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 2669, __PRETTY_FUNCTION__)); | |||
2670 | ||||
2671 | Type *T = V->getType(); | |||
2672 | ||||
2673 | ConstantInt *CI = dyn_cast<ConstantInt>(V); | |||
2674 | ||||
2675 | if (Base == 0) | |||
2676 | return false; | |||
2677 | ||||
2678 | if (Base == 1) { | |||
2679 | Multiple = V; | |||
2680 | return true; | |||
2681 | } | |||
2682 | ||||
2683 | ConstantExpr *CO = dyn_cast<ConstantExpr>(V); | |||
2684 | Constant *BaseVal = ConstantInt::get(T, Base); | |||
2685 | if (CO && CO == BaseVal) { | |||
2686 | // Multiple is 1. | |||
2687 | Multiple = ConstantInt::get(T, 1); | |||
2688 | return true; | |||
2689 | } | |||
2690 | ||||
2691 | if (CI && CI->getZExtValue() % Base == 0) { | |||
2692 | Multiple = ConstantInt::get(T, CI->getZExtValue() / Base); | |||
2693 | return true; | |||
2694 | } | |||
2695 | ||||
2696 | if (Depth == MaxDepth) return false; // Limit search depth. | |||
2697 | ||||
2698 | Operator *I = dyn_cast<Operator>(V); | |||
2699 | if (!I) return false; | |||
2700 | ||||
2701 | switch (I->getOpcode()) { | |||
2702 | default: break; | |||
2703 | case Instruction::SExt: | |||
2704 | if (!LookThroughSExt) return false; | |||
2705 | // otherwise fall through to ZExt | |||
2706 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
2707 | case Instruction::ZExt: | |||
2708 | return ComputeMultiple(I->getOperand(0), Base, Multiple, | |||
2709 | LookThroughSExt, Depth+1); | |||
2710 | case Instruction::Shl: | |||
2711 | case Instruction::Mul: { | |||
2712 | Value *Op0 = I->getOperand(0); | |||
2713 | Value *Op1 = I->getOperand(1); | |||
2714 | ||||
2715 | if (I->getOpcode() == Instruction::Shl) { | |||
2716 | ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1); | |||
2717 | if (!Op1CI) return false; | |||
2718 | // Turn Op0 << Op1 into Op0 * 2^Op1 | |||
2719 | APInt Op1Int = Op1CI->getValue(); | |||
2720 | uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1); | |||
2721 | APInt API(Op1Int.getBitWidth(), 0); | |||
2722 | API.setBit(BitToSet); | |||
2723 | Op1 = ConstantInt::get(V->getContext(), API); | |||
2724 | } | |||
2725 | ||||
2726 | Value *Mul0 = nullptr; | |||
2727 | if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) { | |||
2728 | if (Constant *Op1C = dyn_cast<Constant>(Op1)) | |||
2729 | if (Constant *MulC = dyn_cast<Constant>(Mul0)) { | |||
2730 | if (Op1C->getType()->getPrimitiveSizeInBits() < | |||
2731 | MulC->getType()->getPrimitiveSizeInBits()) | |||
2732 | Op1C = ConstantExpr::getZExt(Op1C, MulC->getType()); | |||
2733 | if (Op1C->getType()->getPrimitiveSizeInBits() > | |||
2734 | MulC->getType()->getPrimitiveSizeInBits()) | |||
2735 | MulC = ConstantExpr::getZExt(MulC, Op1C->getType()); | |||
2736 | ||||
2737 | // V == Base * (Mul0 * Op1), so return (Mul0 * Op1) | |||
2738 | Multiple = ConstantExpr::getMul(MulC, Op1C); | |||
2739 | return true; | |||
2740 | } | |||
2741 | ||||
2742 | if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0)) | |||
2743 | if (Mul0CI->getValue() == 1) { | |||
2744 | // V == Base * Op1, so return Op1 | |||
2745 | Multiple = Op1; | |||
2746 | return true; | |||
2747 | } | |||
2748 | } | |||
2749 | ||||
2750 | Value *Mul1 = nullptr; | |||
2751 | if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) { | |||
2752 | if (Constant *Op0C = dyn_cast<Constant>(Op0)) | |||
2753 | if (Constant *MulC = dyn_cast<Constant>(Mul1)) { | |||
2754 | if (Op0C->getType()->getPrimitiveSizeInBits() < | |||
2755 | MulC->getType()->getPrimitiveSizeInBits()) | |||
2756 | Op0C = ConstantExpr::getZExt(Op0C, MulC->getType()); | |||
2757 | if (Op0C->getType()->getPrimitiveSizeInBits() > | |||
2758 | MulC->getType()->getPrimitiveSizeInBits()) | |||
2759 | MulC = ConstantExpr::getZExt(MulC, Op0C->getType()); | |||
2760 | ||||
2761 | // V == Base * (Mul1 * Op0), so return (Mul1 * Op0) | |||
2762 | Multiple = ConstantExpr::getMul(MulC, Op0C); | |||
2763 | return true; | |||
2764 | } | |||
2765 | ||||
2766 | if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1)) | |||
2767 | if (Mul1CI->getValue() == 1) { | |||
2768 | // V == Base * Op0, so return Op0 | |||
2769 | Multiple = Op0; | |||
2770 | return true; | |||
2771 | } | |||
2772 | } | |||
2773 | } | |||
2774 | } | |||
2775 | ||||
2776 | // We could not determine if V is a multiple of Base. | |||
2777 | return false; | |||
2778 | } | |||
2779 | ||||
2780 | Intrinsic::ID llvm::getIntrinsicForCallSite(ImmutableCallSite ICS, | |||
2781 | const TargetLibraryInfo *TLI) { | |||
2782 | const Function *F = ICS.getCalledFunction(); | |||
2783 | if (!F) | |||
2784 | return Intrinsic::not_intrinsic; | |||
2785 | ||||
2786 | if (F->isIntrinsic()) | |||
2787 | return F->getIntrinsicID(); | |||
2788 | ||||
2789 | if (!TLI) | |||
2790 | return Intrinsic::not_intrinsic; | |||
2791 | ||||
2792 | LibFunc Func; | |||
2793 | // We're going to make assumptions on the semantics of the functions, check | |||
2794 | // that the target knows that it's available in this environment and it does | |||
2795 | // not have local linkage. | |||
2796 | if (!F || F->hasLocalLinkage() || !TLI->getLibFunc(*F, Func)) | |||
2797 | return Intrinsic::not_intrinsic; | |||
2798 | ||||
2799 | if (!ICS.onlyReadsMemory()) | |||
2800 | return Intrinsic::not_intrinsic; | |||
2801 | ||||
2802 | // Otherwise check if we have a call to a function that can be turned into a | |||
2803 | // vector intrinsic. | |||
2804 | switch (Func) { | |||
2805 | default: | |||
2806 | break; | |||
2807 | case LibFunc_sin: | |||
2808 | case LibFunc_sinf: | |||
2809 | case LibFunc_sinl: | |||
2810 | return Intrinsic::sin; | |||
2811 | case LibFunc_cos: | |||
2812 | case LibFunc_cosf: | |||
2813 | case LibFunc_cosl: | |||
2814 | return Intrinsic::cos; | |||
2815 | case LibFunc_exp: | |||
2816 | case LibFunc_expf: | |||
2817 | case LibFunc_expl: | |||
2818 | return Intrinsic::exp; | |||
2819 | case LibFunc_exp2: | |||
2820 | case LibFunc_exp2f: | |||
2821 | case LibFunc_exp2l: | |||
2822 | return Intrinsic::exp2; | |||
2823 | case LibFunc_log: | |||
2824 | case LibFunc_logf: | |||
2825 | case LibFunc_logl: | |||
2826 | return Intrinsic::log; | |||
2827 | case LibFunc_log10: | |||
2828 | case LibFunc_log10f: | |||
2829 | case LibFunc_log10l: | |||
2830 | return Intrinsic::log10; | |||
2831 | case LibFunc_log2: | |||
2832 | case LibFunc_log2f: | |||
2833 | case LibFunc_log2l: | |||
2834 | return Intrinsic::log2; | |||
2835 | case LibFunc_fabs: | |||
2836 | case LibFunc_fabsf: | |||
2837 | case LibFunc_fabsl: | |||
2838 | return Intrinsic::fabs; | |||
2839 | case LibFunc_fmin: | |||
2840 | case LibFunc_fminf: | |||
2841 | case LibFunc_fminl: | |||
2842 | return Intrinsic::minnum; | |||
2843 | case LibFunc_fmax: | |||
2844 | case LibFunc_fmaxf: | |||
2845 | case LibFunc_fmaxl: | |||
2846 | return Intrinsic::maxnum; | |||
2847 | case LibFunc_copysign: | |||
2848 | case LibFunc_copysignf: | |||
2849 | case LibFunc_copysignl: | |||
2850 | return Intrinsic::copysign; | |||
2851 | case LibFunc_floor: | |||
2852 | case LibFunc_floorf: | |||
2853 | case LibFunc_floorl: | |||
2854 | return Intrinsic::floor; | |||
2855 | case LibFunc_ceil: | |||
2856 | case LibFunc_ceilf: | |||
2857 | case LibFunc_ceill: | |||
2858 | return Intrinsic::ceil; | |||
2859 | case LibFunc_trunc: | |||
2860 | case LibFunc_truncf: | |||
2861 | case LibFunc_truncl: | |||
2862 | return Intrinsic::trunc; | |||
2863 | case LibFunc_rint: | |||
2864 | case LibFunc_rintf: | |||
2865 | case LibFunc_rintl: | |||
2866 | return Intrinsic::rint; | |||
2867 | case LibFunc_nearbyint: | |||
2868 | case LibFunc_nearbyintf: | |||
2869 | case LibFunc_nearbyintl: | |||
2870 | return Intrinsic::nearbyint; | |||
2871 | case LibFunc_round: | |||
2872 | case LibFunc_roundf: | |||
2873 | case LibFunc_roundl: | |||
2874 | return Intrinsic::round; | |||
2875 | case LibFunc_pow: | |||
2876 | case LibFunc_powf: | |||
2877 | case LibFunc_powl: | |||
2878 | return Intrinsic::pow; | |||
2879 | case LibFunc_sqrt: | |||
2880 | case LibFunc_sqrtf: | |||
2881 | case LibFunc_sqrtl: | |||
2882 | return Intrinsic::sqrt; | |||
2883 | } | |||
2884 | ||||
2885 | return Intrinsic::not_intrinsic; | |||
2886 | } | |||
2887 | ||||
2888 | /// Return true if we can prove that the specified FP value is never equal to | |||
2889 | /// -0.0. | |||
2890 | /// | |||
2891 | /// NOTE: this function will need to be revisited when we support non-default | |||
2892 | /// rounding modes! | |||
2893 | bool llvm::CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI, | |||
2894 | unsigned Depth) { | |||
2895 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
2896 | return !CFP->getValueAPF().isNegZero(); | |||
2897 | ||||
2898 | // Limit search depth. | |||
2899 | if (Depth == MaxDepth) | |||
2900 | return false; | |||
2901 | ||||
2902 | auto *Op = dyn_cast<Operator>(V); | |||
2903 | if (!Op) | |||
2904 | return false; | |||
2905 | ||||
2906 | // Check if the nsz fast-math flag is set. | |||
2907 | if (auto *FPO = dyn_cast<FPMathOperator>(Op)) | |||
2908 | if (FPO->hasNoSignedZeros()) | |||
2909 | return true; | |||
2910 | ||||
2911 | // (fadd x, 0.0) is guaranteed to return +0.0, not -0.0. | |||
2912 | if (match(Op, m_FAdd(m_Value(), m_PosZeroFP()))) | |||
2913 | return true; | |||
2914 | ||||
2915 | // sitofp and uitofp turn into +0.0 for zero. | |||
2916 | if (isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) | |||
2917 | return true; | |||
2918 | ||||
2919 | if (auto *Call = dyn_cast<CallInst>(Op)) { | |||
2920 | Intrinsic::ID IID = getIntrinsicForCallSite(Call, TLI); | |||
2921 | switch (IID) { | |||
2922 | default: | |||
2923 | break; | |||
2924 | // sqrt(-0.0) = -0.0, no other negative results are possible. | |||
2925 | case Intrinsic::sqrt: | |||
2926 | case Intrinsic::canonicalize: | |||
2927 | return CannotBeNegativeZero(Call->getArgOperand(0), TLI, Depth + 1); | |||
2928 | // fabs(x) != -0.0 | |||
2929 | case Intrinsic::fabs: | |||
2930 | return true; | |||
2931 | } | |||
2932 | } | |||
2933 | ||||
2934 | return false; | |||
2935 | } | |||
2936 | ||||
2937 | /// If \p SignBitOnly is true, test for a known 0 sign bit rather than a | |||
2938 | /// standard ordered compare. e.g. make -0.0 olt 0.0 be true because of the sign | |||
2939 | /// bit despite comparing equal. | |||
2940 | static bool cannotBeOrderedLessThanZeroImpl(const Value *V, | |||
2941 | const TargetLibraryInfo *TLI, | |||
2942 | bool SignBitOnly, | |||
2943 | unsigned Depth) { | |||
2944 | // TODO: This function does not do the right thing when SignBitOnly is true | |||
2945 | // and we're lowering to a hypothetical IEEE 754-compliant-but-evil platform | |||
2946 | // which flips the sign bits of NaNs. See | |||
2947 | // https://llvm.org/bugs/show_bug.cgi?id=31702. | |||
2948 | ||||
2949 | if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { | |||
2950 | return !CFP->getValueAPF().isNegative() || | |||
2951 | (!SignBitOnly && CFP->getValueAPF().isZero()); | |||
2952 | } | |||
2953 | ||||
2954 | // Handle vector of constants. | |||
2955 | if (auto *CV = dyn_cast<Constant>(V)) { | |||
2956 | if (CV->getType()->isVectorTy()) { | |||
2957 | unsigned NumElts = CV->getType()->getVectorNumElements(); | |||
2958 | for (unsigned i = 0; i != NumElts; ++i) { | |||
2959 | auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i)); | |||
2960 | if (!CFP) | |||
2961 | return false; | |||
2962 | if (CFP->getValueAPF().isNegative() && | |||
2963 | (SignBitOnly || !CFP->getValueAPF().isZero())) | |||
2964 | return false; | |||
2965 | } | |||
2966 | ||||
2967 | // All non-negative ConstantFPs. | |||
2968 | return true; | |||
2969 | } | |||
2970 | } | |||
2971 | ||||
2972 | if (Depth == MaxDepth) | |||
2973 | return false; // Limit search depth. | |||
2974 | ||||
2975 | const Operator *I = dyn_cast<Operator>(V); | |||
2976 | if (!I) | |||
2977 | return false; | |||
2978 | ||||
2979 | switch (I->getOpcode()) { | |||
2980 | default: | |||
2981 | break; | |||
2982 | // Unsigned integers are always nonnegative. | |||
2983 | case Instruction::UIToFP: | |||
2984 | return true; | |||
2985 | case Instruction::FMul: | |||
2986 | // x*x is always non-negative or a NaN. | |||
2987 | if (I->getOperand(0) == I->getOperand(1) && | |||
2988 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs())) | |||
2989 | return true; | |||
2990 | ||||
2991 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | |||
2992 | case Instruction::FAdd: | |||
2993 | case Instruction::FDiv: | |||
2994 | case Instruction::FRem: | |||
2995 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
2996 | Depth + 1) && | |||
2997 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
2998 | Depth + 1); | |||
2999 | case Instruction::Select: | |||
3000 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3001 | Depth + 1) && | |||
3002 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, | |||
3003 | Depth + 1); | |||
3004 | case Instruction::FPExt: | |||
3005 | case Instruction::FPTrunc: | |||
3006 | // Widening/narrowing never change sign. | |||
3007 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3008 | Depth + 1); | |||
3009 | case Instruction::ExtractElement: | |||
3010 | // Look through extract element. At the moment we keep this simple and skip | |||
3011 | // tracking the specific element. But at least we might find information | |||
3012 | // valid for all elements of the vector. | |||
3013 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3014 | Depth + 1); | |||
3015 | case Instruction::Call: | |||
3016 | const auto *CI = cast<CallInst>(I); | |||
3017 | Intrinsic::ID IID = getIntrinsicForCallSite(CI, TLI); | |||
3018 | switch (IID) { | |||
3019 | default: | |||
3020 | break; | |||
3021 | case Intrinsic::maxnum: | |||
3022 | return (isKnownNeverNaN(I->getOperand(0), TLI) && | |||
3023 | cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, | |||
3024 | SignBitOnly, Depth + 1)) || | |||
3025 | (isKnownNeverNaN(I->getOperand(1), TLI) && | |||
3026 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, | |||
3027 | SignBitOnly, Depth + 1)); | |||
3028 | ||||
3029 | case Intrinsic::maximum: | |||
3030 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3031 | Depth + 1) || | |||
3032 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3033 | Depth + 1); | |||
3034 | case Intrinsic::minnum: | |||
3035 | case Intrinsic::minimum: | |||
3036 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3037 | Depth + 1) && | |||
3038 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, | |||
3039 | Depth + 1); | |||
3040 | case Intrinsic::exp: | |||
3041 | case Intrinsic::exp2: | |||
3042 | case Intrinsic::fabs: | |||
3043 | return true; | |||
3044 | ||||
3045 | case Intrinsic::sqrt: | |||
3046 | // sqrt(x) is always >= -0 or NaN. Moreover, sqrt(x) == -0 iff x == -0. | |||
3047 | if (!SignBitOnly) | |||
3048 | return true; | |||
3049 | return CI->hasNoNaNs() && (CI->hasNoSignedZeros() || | |||
3050 | CannotBeNegativeZero(CI->getOperand(0), TLI)); | |||
3051 | ||||
3052 | case Intrinsic::powi: | |||
3053 | if (ConstantInt *Exponent = dyn_cast<ConstantInt>(I->getOperand(1))) { | |||
3054 | // powi(x,n) is non-negative if n is even. | |||
3055 | if (Exponent->getBitWidth() <= 64 && Exponent->getSExtValue() % 2u == 0) | |||
3056 | return true; | |||
3057 | } | |||
3058 | // TODO: This is not correct. Given that exp is an integer, here are the | |||
3059 | // ways that pow can return a negative value: | |||
3060 | // | |||
3061 | // pow(x, exp) --> negative if exp is odd and x is negative. | |||
3062 | // pow(-0, exp) --> -inf if exp is negative odd. | |||
3063 | // pow(-0, exp) --> -0 if exp is positive odd. | |||
3064 | // pow(-inf, exp) --> -0 if exp is negative odd. | |||
3065 | // pow(-inf, exp) --> -inf if exp is positive odd. | |||
3066 | // | |||
3067 | // Therefore, if !SignBitOnly, we can return true if x >= +0 or x is NaN, | |||
3068 | // but we must return false if x == -0. Unfortunately we do not currently | |||
3069 | // have a way of expressing this constraint. See details in | |||
3070 | // https://llvm.org/bugs/show_bug.cgi?id=31702. | |||
3071 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, | |||
3072 | Depth + 1); | |||
3073 | ||||
3074 | case Intrinsic::fma: | |||
3075 | case Intrinsic::fmuladd: | |||
3076 | // x*x+y is non-negative if y is non-negative. | |||
3077 | return I->getOperand(0) == I->getOperand(1) && | |||
3078 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()) && | |||
3079 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, | |||
3080 | Depth + 1); | |||
3081 | } | |||
3082 | break; | |||
3083 | } | |||
3084 | return false; | |||
3085 | } | |||
3086 | ||||
3087 | bool llvm::CannotBeOrderedLessThanZero(const Value *V, | |||
3088 | const TargetLibraryInfo *TLI) { | |||
3089 | return cannotBeOrderedLessThanZeroImpl(V, TLI, false, 0); | |||
3090 | } | |||
3091 | ||||
3092 | bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) { | |||
3093 | return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0); | |||
3094 | } | |||
3095 | ||||
3096 | bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI, | |||
3097 | unsigned Depth) { | |||
3098 | assert(V->getType()->isFPOrFPVectorTy() && "Querying for NaN on non-FP type")((V->getType()->isFPOrFPVectorTy() && "Querying for NaN on non-FP type" ) ? static_cast<void> (0) : __assert_fail ("V->getType()->isFPOrFPVectorTy() && \"Querying for NaN on non-FP type\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3098, __PRETTY_FUNCTION__)); | |||
3099 | ||||
3100 | // If we're told that NaNs won't happen, assume they won't. | |||
3101 | if (auto *FPMathOp = dyn_cast<FPMathOperator>(V)) | |||
3102 | if (FPMathOp->hasNoNaNs()) | |||
3103 | return true; | |||
3104 | ||||
3105 | // Handle scalar constants. | |||
3106 | if (auto *CFP = dyn_cast<ConstantFP>(V)) | |||
3107 | return !CFP->isNaN(); | |||
3108 | ||||
3109 | if (Depth == MaxDepth) | |||
3110 | return false; | |||
3111 | ||||
3112 | if (auto *Inst = dyn_cast<Instruction>(V)) { | |||
3113 | switch (Inst->getOpcode()) { | |||
3114 | case Instruction::FAdd: | |||
3115 | case Instruction::FMul: | |||
3116 | case Instruction::FSub: | |||
3117 | case Instruction::FDiv: | |||
3118 | case Instruction::FRem: { | |||
3119 | // TODO: Need isKnownNeverInfinity | |||
3120 | return false; | |||
3121 | } | |||
3122 | case Instruction::Select: { | |||
3123 | return isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && | |||
3124 | isKnownNeverNaN(Inst->getOperand(2), TLI, Depth + 1); | |||
3125 | } | |||
3126 | case Instruction::SIToFP: | |||
3127 | case Instruction::UIToFP: | |||
3128 | return true; | |||
3129 | case Instruction::FPTrunc: | |||
3130 | case Instruction::FPExt: | |||
3131 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1); | |||
3132 | default: | |||
3133 | break; | |||
3134 | } | |||
3135 | } | |||
3136 | ||||
3137 | if (const auto *II = dyn_cast<IntrinsicInst>(V)) { | |||
3138 | switch (II->getIntrinsicID()) { | |||
3139 | case Intrinsic::canonicalize: | |||
3140 | case Intrinsic::fabs: | |||
3141 | case Intrinsic::copysign: | |||
3142 | case Intrinsic::exp: | |||
3143 | case Intrinsic::exp2: | |||
3144 | case Intrinsic::floor: | |||
3145 | case Intrinsic::ceil: | |||
3146 | case Intrinsic::trunc: | |||
3147 | case Intrinsic::rint: | |||
3148 | case Intrinsic::nearbyint: | |||
3149 | case Intrinsic::round: | |||
3150 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1); | |||
3151 | case Intrinsic::sqrt: | |||
3152 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) && | |||
3153 | CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI); | |||
3154 | case Intrinsic::minnum: | |||
3155 | case Intrinsic::maxnum: | |||
3156 | // If either operand is not NaN, the result is not NaN. | |||
3157 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) || | |||
3158 | isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1); | |||
3159 | default: | |||
3160 | return false; | |||
3161 | } | |||
3162 | } | |||
3163 | ||||
3164 | // Bail out for constant expressions, but try to handle vector constants. | |||
3165 | if (!V->getType()->isVectorTy() || !isa<Constant>(V)) | |||
3166 | return false; | |||
3167 | ||||
3168 | // For vectors, verify that each element is not NaN. | |||
3169 | unsigned NumElts = V->getType()->getVectorNumElements(); | |||
3170 | for (unsigned i = 0; i != NumElts; ++i) { | |||
3171 | Constant *Elt = cast<Constant>(V)->getAggregateElement(i); | |||
3172 | if (!Elt) | |||
3173 | return false; | |||
3174 | if (isa<UndefValue>(Elt)) | |||
3175 | continue; | |||
3176 | auto *CElt = dyn_cast<ConstantFP>(Elt); | |||
3177 | if (!CElt || CElt->isNaN()) | |||
3178 | return false; | |||
3179 | } | |||
3180 | // All elements were confirmed not-NaN or undefined. | |||
3181 | return true; | |||
3182 | } | |||
3183 | ||||
3184 | Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) { | |||
3185 | ||||
3186 | // All byte-wide stores are splatable, even of arbitrary variables. | |||
3187 | if (V->getType()->isIntegerTy(8)) | |||
3188 | return V; | |||
3189 | ||||
3190 | LLVMContext &Ctx = V->getContext(); | |||
3191 | ||||
3192 | // Undef don't care. | |||
3193 | auto *UndefInt8 = UndefValue::get(Type::getInt8Ty(Ctx)); | |||
3194 | if (isa<UndefValue>(V)) | |||
3195 | return UndefInt8; | |||
3196 | ||||
3197 | const uint64_t Size = DL.getTypeStoreSize(V->getType()); | |||
3198 | if (!Size) | |||
3199 | return UndefInt8; | |||
3200 | ||||
3201 | Constant *C = dyn_cast<Constant>(V); | |||
3202 | if (!C) { | |||
3203 | // Conceptually, we could handle things like: | |||
3204 | // %a = zext i8 %X to i16 | |||
3205 | // %b = shl i16 %a, 8 | |||
3206 | // %c = or i16 %a, %b | |||
3207 | // but until there is an example that actually needs this, it doesn't seem | |||
3208 | // worth worrying about. | |||
3209 | return nullptr; | |||
3210 | } | |||
3211 | ||||
3212 | // Handle 'null' ConstantArrayZero etc. | |||
3213 | if (C->isNullValue()) | |||
3214 | return Constant::getNullValue(Type::getInt8Ty(Ctx)); | |||
3215 | ||||
3216 | // Constant floating-point values can be handled as integer values if the | |||
3217 | // corresponding integer value is "byteable". An important case is 0.0. | |||
3218 | if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) { | |||
3219 | Type *Ty = nullptr; | |||
3220 | if (CFP->getType()->isHalfTy()) | |||
3221 | Ty = Type::getInt16Ty(Ctx); | |||
3222 | else if (CFP->getType()->isFloatTy()) | |||
3223 | Ty = Type::getInt32Ty(Ctx); | |||
3224 | else if (CFP->getType()->isDoubleTy()) | |||
3225 | Ty = Type::getInt64Ty(Ctx); | |||
3226 | // Don't handle long double formats, which have strange constraints. | |||
3227 | return Ty ? isBytewiseValue(ConstantExpr::getBitCast(CFP, Ty), DL) | |||
3228 | : nullptr; | |||
3229 | } | |||
3230 | ||||
3231 | // We can handle constant integers that are multiple of 8 bits. | |||
3232 | if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { | |||
3233 | if (CI->getBitWidth() % 8 == 0) { | |||
3234 | assert(CI->getBitWidth() > 8 && "8 bits should be handled above!")((CI->getBitWidth() > 8 && "8 bits should be handled above!" ) ? static_cast<void> (0) : __assert_fail ("CI->getBitWidth() > 8 && \"8 bits should be handled above!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3234, __PRETTY_FUNCTION__)); | |||
3235 | if (!CI->getValue().isSplat(8)) | |||
3236 | return nullptr; | |||
3237 | return ConstantInt::get(Ctx, CI->getValue().trunc(8)); | |||
3238 | } | |||
3239 | } | |||
3240 | ||||
3241 | if (auto *CE = dyn_cast<ConstantExpr>(C)) { | |||
3242 | if (CE->getOpcode() == Instruction::IntToPtr) { | |||
3243 | auto PS = DL.getPointerSizeInBits( | |||
3244 | cast<PointerType>(CE->getType())->getAddressSpace()); | |||
3245 | return isBytewiseValue( | |||
3246 | ConstantExpr::getIntegerCast(CE->getOperand(0), | |||
3247 | Type::getIntNTy(Ctx, PS), false), | |||
3248 | DL); | |||
3249 | } | |||
3250 | } | |||
3251 | ||||
3252 | auto Merge = [&](Value *LHS, Value *RHS) -> Value * { | |||
3253 | if (LHS == RHS) | |||
3254 | return LHS; | |||
3255 | if (!LHS || !RHS) | |||
3256 | return nullptr; | |||
3257 | if (LHS == UndefInt8) | |||
3258 | return RHS; | |||
3259 | if (RHS == UndefInt8) | |||
3260 | return LHS; | |||
3261 | return nullptr; | |||
3262 | }; | |||
3263 | ||||
3264 | if (ConstantDataSequential *CA = dyn_cast<ConstantDataSequential>(C)) { | |||
3265 | Value *Val = UndefInt8; | |||
3266 | for (unsigned I = 0, E = CA->getNumElements(); I != E; ++I) | |||
3267 | if (!(Val = Merge(Val, isBytewiseValue(CA->getElementAsConstant(I), DL)))) | |||
3268 | return nullptr; | |||
3269 | return Val; | |||
3270 | } | |||
3271 | ||||
3272 | if (isa<ConstantAggregate>(C)) { | |||
3273 | Value *Val = UndefInt8; | |||
3274 | for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) | |||
3275 | if (!(Val = Merge(Val, isBytewiseValue(C->getOperand(I), DL)))) | |||
3276 | return nullptr; | |||
3277 | return Val; | |||
3278 | } | |||
3279 | ||||
3280 | // Don't try to handle the handful of other constants. | |||
3281 | return nullptr; | |||
3282 | } | |||
3283 | ||||
3284 | // This is the recursive version of BuildSubAggregate. It takes a few different | |||
3285 | // arguments. Idxs is the index within the nested struct From that we are | |||
3286 | // looking at now (which is of type IndexedType). IdxSkip is the number of | |||
3287 | // indices from Idxs that should be left out when inserting into the resulting | |||
3288 | // struct. To is the result struct built so far, new insertvalue instructions | |||
3289 | // build on that. | |||
3290 | static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType, | |||
3291 | SmallVectorImpl<unsigned> &Idxs, | |||
3292 | unsigned IdxSkip, | |||
3293 | Instruction *InsertBefore) { | |||
3294 | StructType *STy = dyn_cast<StructType>(IndexedType); | |||
3295 | if (STy) { | |||
3296 | // Save the original To argument so we can modify it | |||
3297 | Value *OrigTo = To; | |||
3298 | // General case, the type indexed by Idxs is a struct | |||
3299 | for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { | |||
3300 | // Process each struct element recursively | |||
3301 | Idxs.push_back(i); | |||
3302 | Value *PrevTo = To; | |||
3303 | To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, | |||
3304 | InsertBefore); | |||
3305 | Idxs.pop_back(); | |||
3306 | if (!To) { | |||
3307 | // Couldn't find any inserted value for this index? Cleanup | |||
3308 | while (PrevTo != OrigTo) { | |||
3309 | InsertValueInst* Del = cast<InsertValueInst>(PrevTo); | |||
3310 | PrevTo = Del->getAggregateOperand(); | |||
3311 | Del->eraseFromParent(); | |||
3312 | } | |||
3313 | // Stop processing elements | |||
3314 | break; | |||
3315 | } | |||
3316 | } | |||
3317 | // If we successfully found a value for each of our subaggregates | |||
3318 | if (To) | |||
3319 | return To; | |||
3320 | } | |||
3321 | // Base case, the type indexed by SourceIdxs is not a struct, or not all of | |||
3322 | // the struct's elements had a value that was inserted directly. In the latter | |||
3323 | // case, perhaps we can't determine each of the subelements individually, but | |||
3324 | // we might be able to find the complete struct somewhere. | |||
3325 | ||||
3326 | // Find the value that is at that particular spot | |||
3327 | Value *V = FindInsertedValue(From, Idxs); | |||
3328 | ||||
3329 | if (!V) | |||
3330 | return nullptr; | |||
3331 | ||||
3332 | // Insert the value in the new (sub) aggregate | |||
3333 | return InsertValueInst::Create(To, V, makeArrayRef(Idxs).slice(IdxSkip), | |||
3334 | "tmp", InsertBefore); | |||
3335 | } | |||
3336 | ||||
3337 | // This helper takes a nested struct and extracts a part of it (which is again a | |||
3338 | // struct) into a new value. For example, given the struct: | |||
3339 | // { a, { b, { c, d }, e } } | |||
3340 | // and the indices "1, 1" this returns | |||
3341 | // { c, d }. | |||
3342 | // | |||
3343 | // It does this by inserting an insertvalue for each element in the resulting | |||
3344 | // struct, as opposed to just inserting a single struct. This will only work if | |||
3345 | // each of the elements of the substruct are known (ie, inserted into From by an | |||
3346 | // insertvalue instruction somewhere). | |||
3347 | // | |||
3348 | // All inserted insertvalue instructions are inserted before InsertBefore | |||
3349 | static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range, | |||
3350 | Instruction *InsertBefore) { | |||
3351 | assert(InsertBefore && "Must have someplace to insert!")((InsertBefore && "Must have someplace to insert!") ? static_cast<void> (0) : __assert_fail ("InsertBefore && \"Must have someplace to insert!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3351, __PRETTY_FUNCTION__)); | |||
3352 | Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), | |||
3353 | idx_range); | |||
3354 | Value *To = UndefValue::get(IndexedType); | |||
3355 | SmallVector<unsigned, 10> Idxs(idx_range.begin(), idx_range.end()); | |||
3356 | unsigned IdxSkip = Idxs.size(); | |||
3357 | ||||
3358 | return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); | |||
3359 | } | |||
3360 | ||||
3361 | /// Given an aggregate and a sequence of indices, see if the scalar value | |||
3362 | /// indexed is already around as a register, for example if it was inserted | |||
3363 | /// directly into the aggregate. | |||
3364 | /// | |||
3365 | /// If InsertBefore is not null, this function will duplicate (modified) | |||
3366 | /// insertvalues when a part of a nested struct is extracted. | |||
3367 | Value *llvm::FindInsertedValue(Value *V, ArrayRef<unsigned> idx_range, | |||
3368 | Instruction *InsertBefore) { | |||
3369 | // Nothing to index? Just return V then (this is useful at the end of our | |||
3370 | // recursion). | |||
3371 | if (idx_range.empty()) | |||
3372 | return V; | |||
3373 | // We have indices, so V should have an indexable type. | |||
3374 | assert((V->getType()->isStructTy() || V->getType()->isArrayTy()) &&(((V->getType()->isStructTy() || V->getType()->isArrayTy ()) && "Not looking at a struct or array?") ? static_cast <void> (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3375, __PRETTY_FUNCTION__)) | |||
3375 | "Not looking at a struct or array?")(((V->getType()->isStructTy() || V->getType()->isArrayTy ()) && "Not looking at a struct or array?") ? static_cast <void> (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3375, __PRETTY_FUNCTION__)); | |||
3376 | assert(ExtractValueInst::getIndexedType(V->getType(), idx_range) &&((ExtractValueInst::getIndexedType(V->getType(), idx_range ) && "Invalid indices for type?") ? static_cast<void > (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3377, __PRETTY_FUNCTION__)) | |||
3377 | "Invalid indices for type?")((ExtractValueInst::getIndexedType(V->getType(), idx_range ) && "Invalid indices for type?") ? static_cast<void > (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3377, __PRETTY_FUNCTION__)); | |||
3378 | ||||
3379 | if (Constant *C = dyn_cast<Constant>(V)) { | |||
3380 | C = C->getAggregateElement(idx_range[0]); | |||
3381 | if (!C) return nullptr; | |||
3382 | return FindInsertedValue(C, idx_range.slice(1), InsertBefore); | |||
3383 | } | |||
3384 | ||||
3385 | if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) { | |||
3386 | // Loop the indices for the insertvalue instruction in parallel with the | |||
3387 | // requested indices | |||
3388 | const unsigned *req_idx = idx_range.begin(); | |||
3389 | for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); | |||
3390 | i != e; ++i, ++req_idx) { | |||
3391 | if (req_idx == idx_range.end()) { | |||
3392 | // We can't handle this without inserting insertvalues | |||
3393 | if (!InsertBefore) | |||
3394 | return nullptr; | |||
3395 | ||||
3396 | // The requested index identifies a part of a nested aggregate. Handle | |||
3397 | // this specially. For example, | |||
3398 | // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0 | |||
3399 | // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1 | |||
3400 | // %C = extractvalue {i32, { i32, i32 } } %B, 1 | |||
3401 | // This can be changed into | |||
3402 | // %A = insertvalue {i32, i32 } undef, i32 10, 0 | |||
3403 | // %C = insertvalue {i32, i32 } %A, i32 11, 1 | |||
3404 | // which allows the unused 0,0 element from the nested struct to be | |||
3405 | // removed. | |||
3406 | return BuildSubAggregate(V, makeArrayRef(idx_range.begin(), req_idx), | |||
3407 | InsertBefore); | |||
3408 | } | |||
3409 | ||||
3410 | // This insert value inserts something else than what we are looking for. | |||
3411 | // See if the (aggregate) value inserted into has the value we are | |||
3412 | // looking for, then. | |||
3413 | if (*req_idx != *i) | |||
3414 | return FindInsertedValue(I->getAggregateOperand(), idx_range, | |||
3415 | InsertBefore); | |||
3416 | } | |||
3417 | // If we end up here, the indices of the insertvalue match with those | |||
3418 | // requested (though possibly only partially). Now we recursively look at | |||
3419 | // the inserted value, passing any remaining indices. | |||
3420 | return FindInsertedValue(I->getInsertedValueOperand(), | |||
3421 | makeArrayRef(req_idx, idx_range.end()), | |||
3422 | InsertBefore); | |||
3423 | } | |||
3424 | ||||
3425 | if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) { | |||
3426 | // If we're extracting a value from an aggregate that was extracted from | |||
3427 | // something else, we can extract from that something else directly instead. | |||
3428 | // However, we will need to chain I's indices with the requested indices. | |||
3429 | ||||
3430 | // Calculate the number of indices required | |||
3431 | unsigned size = I->getNumIndices() + idx_range.size(); | |||
3432 | // Allocate some space to put the new indices in | |||
3433 | SmallVector<unsigned, 5> Idxs; | |||
3434 | Idxs.reserve(size); | |||
3435 | // Add indices from the extract value instruction | |||
3436 | Idxs.append(I->idx_begin(), I->idx_end()); | |||
3437 | ||||
3438 | // Add requested indices | |||
3439 | Idxs.append(idx_range.begin(), idx_range.end()); | |||
3440 | ||||
3441 | assert(Idxs.size() == size((Idxs.size() == size && "Number of indices added not correct?" ) ? static_cast<void> (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3442, __PRETTY_FUNCTION__)) | |||
3442 | && "Number of indices added not correct?")((Idxs.size() == size && "Number of indices added not correct?" ) ? static_cast<void> (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3442, __PRETTY_FUNCTION__)); | |||
3443 | ||||
3444 | return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore); | |||
3445 | } | |||
3446 | // Otherwise, we don't know (such as, extracting from a function return value | |||
3447 | // or load instruction) | |||
3448 | return nullptr; | |||
3449 | } | |||
3450 | ||||
3451 | bool llvm::isGEPBasedOnPointerToString(const GEPOperator *GEP, | |||
3452 | unsigned CharSize) { | |||
3453 | // Make sure the GEP has exactly three arguments. | |||
3454 | if (GEP->getNumOperands() != 3) | |||
3455 | return false; | |||
3456 | ||||
3457 | // Make sure the index-ee is a pointer to array of \p CharSize integers. | |||
3458 | // CharSize. | |||
3459 | ArrayType *AT = dyn_cast<ArrayType>(GEP->getSourceElementType()); | |||
3460 | if (!AT || !AT->getElementType()->isIntegerTy(CharSize)) | |||
3461 | return false; | |||
3462 | ||||
3463 | // Check to make sure that the first operand of the GEP is an integer and | |||
3464 | // has value 0 so that we are sure we're indexing into the initializer. | |||
3465 | const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1)); | |||
3466 | if (!FirstIdx || !FirstIdx->isZero()) | |||
3467 | return false; | |||
3468 | ||||
3469 | return true; | |||
3470 | } | |||
3471 | ||||
3472 | bool llvm::getConstantDataArrayInfo(const Value *V, | |||
3473 | ConstantDataArraySlice &Slice, | |||
3474 | unsigned ElementSize, uint64_t Offset) { | |||
3475 | assert(V)((V) ? static_cast<void> (0) : __assert_fail ("V", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3475, __PRETTY_FUNCTION__)); | |||
3476 | ||||
3477 | // Look through bitcast instructions and geps. | |||
3478 | V = V->stripPointerCasts(); | |||
3479 | ||||
3480 | // If the value is a GEP instruction or constant expression, treat it as an | |||
3481 | // offset. | |||
3482 | if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { | |||
3483 | // The GEP operator should be based on a pointer to string constant, and is | |||
3484 | // indexing into the string constant. | |||
3485 | if (!isGEPBasedOnPointerToString(GEP, ElementSize)) | |||
3486 | return false; | |||
3487 | ||||
3488 | // If the second index isn't a ConstantInt, then this is a variable index | |||
3489 | // into the array. If this occurs, we can't say anything meaningful about | |||
3490 | // the string. | |||
3491 | uint64_t StartIdx = 0; | |||
3492 | if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) | |||
3493 | StartIdx = CI->getZExtValue(); | |||
3494 | else | |||
3495 | return false; | |||
3496 | return getConstantDataArrayInfo(GEP->getOperand(0), Slice, ElementSize, | |||
3497 | StartIdx + Offset); | |||
3498 | } | |||
3499 | ||||
3500 | // The GEP instruction, constant or instruction, must reference a global | |||
3501 | // variable that is a constant and is initialized. The referenced constant | |||
3502 | // initializer is the array that we'll use for optimization. | |||
3503 | const GlobalVariable *GV = dyn_cast<GlobalVariable>(V); | |||
3504 | if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) | |||
3505 | return false; | |||
3506 | ||||
3507 | const ConstantDataArray *Array; | |||
3508 | ArrayType *ArrayTy; | |||
3509 | if (GV->getInitializer()->isNullValue()) { | |||
3510 | Type *GVTy = GV->getValueType(); | |||
3511 | if ( (ArrayTy = dyn_cast<ArrayType>(GVTy)) ) { | |||
3512 | // A zeroinitializer for the array; there is no ConstantDataArray. | |||
3513 | Array = nullptr; | |||
3514 | } else { | |||
3515 | const DataLayout &DL = GV->getParent()->getDataLayout(); | |||
3516 | uint64_t SizeInBytes = DL.getTypeStoreSize(GVTy); | |||
3517 | uint64_t Length = SizeInBytes / (ElementSize / 8); | |||
3518 | if (Length <= Offset) | |||
3519 | return false; | |||
3520 | ||||
3521 | Slice.Array = nullptr; | |||
3522 | Slice.Offset = 0; | |||
3523 | Slice.Length = Length - Offset; | |||
3524 | return true; | |||
3525 | } | |||
3526 | } else { | |||
3527 | // This must be a ConstantDataArray. | |||
3528 | Array = dyn_cast<ConstantDataArray>(GV->getInitializer()); | |||
3529 | if (!Array) | |||
3530 | return false; | |||
3531 | ArrayTy = Array->getType(); | |||
3532 | } | |||
3533 | if (!ArrayTy->getElementType()->isIntegerTy(ElementSize)) | |||
3534 | return false; | |||
3535 | ||||
3536 | uint64_t NumElts = ArrayTy->getArrayNumElements(); | |||
3537 | if (Offset > NumElts) | |||
3538 | return false; | |||
3539 | ||||
3540 | Slice.Array = Array; | |||
3541 | Slice.Offset = Offset; | |||
3542 | Slice.Length = NumElts - Offset; | |||
3543 | return true; | |||
3544 | } | |||
3545 | ||||
3546 | /// This function computes the length of a null-terminated C string pointed to | |||
3547 | /// by V. If successful, it returns true and returns the string in Str. | |||
3548 | /// If unsuccessful, it returns false. | |||
3549 | bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, | |||
3550 | uint64_t Offset, bool TrimAtNul) { | |||
3551 | ConstantDataArraySlice Slice; | |||
3552 | if (!getConstantDataArrayInfo(V, Slice, 8, Offset)) | |||
3553 | return false; | |||
3554 | ||||
3555 | if (Slice.Array == nullptr) { | |||
3556 | if (TrimAtNul) { | |||
3557 | Str = StringRef(); | |||
3558 | return true; | |||
3559 | } | |||
3560 | if (Slice.Length == 1) { | |||
3561 | Str = StringRef("", 1); | |||
3562 | return true; | |||
3563 | } | |||
3564 | // We cannot instantiate a StringRef as we do not have an appropriate string | |||
3565 | // of 0s at hand. | |||
3566 | return false; | |||
3567 | } | |||
3568 | ||||
3569 | // Start out with the entire array in the StringRef. | |||
3570 | Str = Slice.Array->getAsString(); | |||
3571 | // Skip over 'offset' bytes. | |||
3572 | Str = Str.substr(Slice.Offset); | |||
3573 | ||||
3574 | if (TrimAtNul) { | |||
3575 | // Trim off the \0 and anything after it. If the array is not nul | |||
3576 | // terminated, we just return the whole end of string. The client may know | |||
3577 | // some other way that the string is length-bound. | |||
3578 | Str = Str.substr(0, Str.find('\0')); | |||
3579 | } | |||
3580 | return true; | |||
3581 | } | |||
3582 | ||||
3583 | // These next two are very similar to the above, but also look through PHI | |||
3584 | // nodes. | |||
3585 | // TODO: See if we can integrate these two together. | |||
3586 | ||||
3587 | /// If we can compute the length of the string pointed to by | |||
3588 | /// the specified pointer, return 'len+1'. If we can't, return 0. | |||
3589 | static uint64_t GetStringLengthH(const Value *V, | |||
3590 | SmallPtrSetImpl<const PHINode*> &PHIs, | |||
3591 | unsigned CharSize) { | |||
3592 | // Look through noop bitcast instructions. | |||
3593 | V = V->stripPointerCasts(); | |||
3594 | ||||
3595 | // If this is a PHI node, there are two cases: either we have already seen it | |||
3596 | // or we haven't. | |||
3597 | if (const PHINode *PN = dyn_cast<PHINode>(V)) { | |||
3598 | if (!PHIs.insert(PN).second) | |||
3599 | return ~0ULL; // already in the set. | |||
3600 | ||||
3601 | // If it was new, see if all the input strings are the same length. | |||
3602 | uint64_t LenSoFar = ~0ULL; | |||
3603 | for (Value *IncValue : PN->incoming_values()) { | |||
3604 | uint64_t Len = GetStringLengthH(IncValue, PHIs, CharSize); | |||
3605 | if (Len == 0) return 0; // Unknown length -> unknown. | |||
3606 | ||||
3607 | if (Len == ~0ULL) continue; | |||
3608 | ||||
3609 | if (Len != LenSoFar && LenSoFar != ~0ULL) | |||
3610 | return 0; // Disagree -> unknown. | |||
3611 | LenSoFar = Len; | |||
3612 | } | |||
3613 | ||||
3614 | // Success, all agree. | |||
3615 | return LenSoFar; | |||
3616 | } | |||
3617 | ||||
3618 | // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) | |||
3619 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) { | |||
3620 | uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs, CharSize); | |||
3621 | if (Len1 == 0) return 0; | |||
3622 | uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs, CharSize); | |||
3623 | if (Len2 == 0) return 0; | |||
3624 | if (Len1 == ~0ULL) return Len2; | |||
3625 | if (Len2 == ~0ULL) return Len1; | |||
3626 | if (Len1 != Len2) return 0; | |||
3627 | return Len1; | |||
3628 | } | |||
3629 | ||||
3630 | // Otherwise, see if we can read the string. | |||
3631 | ConstantDataArraySlice Slice; | |||
3632 | if (!getConstantDataArrayInfo(V, Slice, CharSize)) | |||
3633 | return 0; | |||
3634 | ||||
3635 | if (Slice.Array == nullptr) | |||
3636 | return 1; | |||
3637 | ||||
3638 | // Search for nul characters | |||
3639 | unsigned NullIndex = 0; | |||
3640 | for (unsigned E = Slice.Length; NullIndex < E; ++NullIndex) { | |||
3641 | if (Slice.Array->getElementAsInteger(Slice.Offset + NullIndex) == 0) | |||
3642 | break; | |||
3643 | } | |||
3644 | ||||
3645 | return NullIndex + 1; | |||
3646 | } | |||
3647 | ||||
3648 | /// If we can compute the length of the string pointed to by | |||
3649 | /// the specified pointer, return 'len+1'. If we can't, return 0. | |||
3650 | uint64_t llvm::GetStringLength(const Value *V, unsigned CharSize) { | |||
3651 | if (!V->getType()->isPointerTy()) | |||
3652 | return 0; | |||
3653 | ||||
3654 | SmallPtrSet<const PHINode*, 32> PHIs; | |||
3655 | uint64_t Len = GetStringLengthH(V, PHIs, CharSize); | |||
3656 | // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return | |||
3657 | // an empty string as a length. | |||
3658 | return Len == ~0ULL ? 1 : Len; | |||
3659 | } | |||
3660 | ||||
3661 | const Value * | |||
3662 | llvm::getArgumentAliasingToReturnedPointer(const CallBase *Call, | |||
3663 | bool MustPreserveNullness) { | |||
3664 | assert(Call &&((Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls" ) ? static_cast<void> (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3665, __PRETTY_FUNCTION__)) | |||
3665 | "getArgumentAliasingToReturnedPointer only works on nonnull calls")((Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls" ) ? static_cast<void> (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3665, __PRETTY_FUNCTION__)); | |||
3666 | if (const Value *RV = Call->getReturnedArgOperand()) | |||
3667 | return RV; | |||
3668 | // This can be used only as a aliasing property. | |||
3669 | if (isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( | |||
3670 | Call, MustPreserveNullness)) | |||
3671 | return Call->getArgOperand(0); | |||
3672 | return nullptr; | |||
3673 | } | |||
3674 | ||||
3675 | bool llvm::isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( | |||
3676 | const CallBase *Call, bool MustPreserveNullness) { | |||
3677 | return Call->getIntrinsicID() == Intrinsic::launder_invariant_group || | |||
3678 | Call->getIntrinsicID() == Intrinsic::strip_invariant_group || | |||
3679 | Call->getIntrinsicID() == Intrinsic::aarch64_irg || | |||
3680 | Call->getIntrinsicID() == Intrinsic::aarch64_tagp || | |||
3681 | (!MustPreserveNullness && | |||
3682 | Call->getIntrinsicID() == Intrinsic::ptrmask); | |||
3683 | } | |||
3684 | ||||
3685 | /// \p PN defines a loop-variant pointer to an object. Check if the | |||
3686 | /// previous iteration of the loop was referring to the same object as \p PN. | |||
3687 | static bool isSameUnderlyingObjectInLoop(const PHINode *PN, | |||
3688 | const LoopInfo *LI) { | |||
3689 | // Find the loop-defined value. | |||
3690 | Loop *L = LI->getLoopFor(PN->getParent()); | |||
3691 | if (PN->getNumIncomingValues() != 2) | |||
3692 | return true; | |||
3693 | ||||
3694 | // Find the value from previous iteration. | |||
3695 | auto *PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(0)); | |||
3696 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) | |||
3697 | PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(1)); | |||
3698 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) | |||
3699 | return true; | |||
3700 | ||||
3701 | // If a new pointer is loaded in the loop, the pointer references a different | |||
3702 | // object in every iteration. E.g.: | |||
3703 | // for (i) | |||
3704 | // int *p = a[i]; | |||
3705 | // ... | |||
3706 | if (auto *Load = dyn_cast<LoadInst>(PrevValue)) | |||
3707 | if (!L->isLoopInvariant(Load->getPointerOperand())) | |||
3708 | return false; | |||
3709 | return true; | |||
3710 | } | |||
3711 | ||||
3712 | Value *llvm::GetUnderlyingObject(Value *V, const DataLayout &DL, | |||
3713 | unsigned MaxLookup) { | |||
3714 | if (!V->getType()->isPointerTy()) | |||
3715 | return V; | |||
3716 | for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { | |||
3717 | if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { | |||
3718 | V = GEP->getPointerOperand(); | |||
3719 | } else if (Operator::getOpcode(V) == Instruction::BitCast || | |||
3720 | Operator::getOpcode(V) == Instruction::AddrSpaceCast) { | |||
3721 | V = cast<Operator>(V)->getOperand(0); | |||
3722 | } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { | |||
3723 | if (GA->isInterposable()) | |||
3724 | return V; | |||
3725 | V = GA->getAliasee(); | |||
3726 | } else if (isa<AllocaInst>(V)) { | |||
3727 | // An alloca can't be further simplified. | |||
3728 | return V; | |||
3729 | } else { | |||
3730 | if (auto *Call = dyn_cast<CallBase>(V)) { | |||
3731 | // CaptureTracking can know about special capturing properties of some | |||
3732 | // intrinsics like launder.invariant.group, that can't be expressed with | |||
3733 | // the attributes, but have properties like returning aliasing pointer. | |||
3734 | // Because some analysis may assume that nocaptured pointer is not | |||
3735 | // returned from some special intrinsic (because function would have to | |||
3736 | // be marked with returns attribute), it is crucial to use this function | |||
3737 | // because it should be in sync with CaptureTracking. Not using it may | |||
3738 | // cause weird miscompilations where 2 aliasing pointers are assumed to | |||
3739 | // noalias. | |||
3740 | if (auto *RP = getArgumentAliasingToReturnedPointer(Call, false)) { | |||
3741 | V = RP; | |||
3742 | continue; | |||
3743 | } | |||
3744 | } | |||
3745 | ||||
3746 | // See if InstructionSimplify knows any relevant tricks. | |||
3747 | if (Instruction *I = dyn_cast<Instruction>(V)) | |||
3748 | // TODO: Acquire a DominatorTree and AssumptionCache and use them. | |||
3749 | if (Value *Simplified = SimplifyInstruction(I, {DL, I})) { | |||
3750 | V = Simplified; | |||
3751 | continue; | |||
3752 | } | |||
3753 | ||||
3754 | return V; | |||
3755 | } | |||
3756 | assert(V->getType()->isPointerTy() && "Unexpected operand type!")((V->getType()->isPointerTy() && "Unexpected operand type!" ) ? static_cast<void> (0) : __assert_fail ("V->getType()->isPointerTy() && \"Unexpected operand type!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3756, __PRETTY_FUNCTION__)); | |||
3757 | } | |||
3758 | return V; | |||
3759 | } | |||
3760 | ||||
3761 | void llvm::GetUnderlyingObjects(const Value *V, | |||
3762 | SmallVectorImpl<const Value *> &Objects, | |||
3763 | const DataLayout &DL, LoopInfo *LI, | |||
3764 | unsigned MaxLookup) { | |||
3765 | SmallPtrSet<const Value *, 4> Visited; | |||
3766 | SmallVector<const Value *, 4> Worklist; | |||
3767 | Worklist.push_back(V); | |||
3768 | do { | |||
3769 | const Value *P = Worklist.pop_back_val(); | |||
3770 | P = GetUnderlyingObject(P, DL, MaxLookup); | |||
3771 | ||||
3772 | if (!Visited.insert(P).second) | |||
3773 | continue; | |||
3774 | ||||
3775 | if (auto *SI = dyn_cast<SelectInst>(P)) { | |||
3776 | Worklist.push_back(SI->getTrueValue()); | |||
3777 | Worklist.push_back(SI->getFalseValue()); | |||
3778 | continue; | |||
3779 | } | |||
3780 | ||||
3781 | if (auto *PN = dyn_cast<PHINode>(P)) { | |||
3782 | // If this PHI changes the underlying object in every iteration of the | |||
3783 | // loop, don't look through it. Consider: | |||
3784 | // int **A; | |||
3785 | // for (i) { | |||
3786 | // Prev = Curr; // Prev = PHI (Prev_0, Curr) | |||
3787 | // Curr = A[i]; | |||
3788 | // *Prev, *Curr; | |||
3789 | // | |||
3790 | // Prev is tracking Curr one iteration behind so they refer to different | |||
3791 | // underlying objects. | |||
3792 | if (!LI || !LI->isLoopHeader(PN->getParent()) || | |||
3793 | isSameUnderlyingObjectInLoop(PN, LI)) | |||
3794 | for (Value *IncValue : PN->incoming_values()) | |||
3795 | Worklist.push_back(IncValue); | |||
3796 | continue; | |||
3797 | } | |||
3798 | ||||
3799 | Objects.push_back(P); | |||
3800 | } while (!Worklist.empty()); | |||
3801 | } | |||
3802 | ||||
3803 | /// This is the function that does the work of looking through basic | |||
3804 | /// ptrtoint+arithmetic+inttoptr sequences. | |||
3805 | static const Value *getUnderlyingObjectFromInt(const Value *V) { | |||
3806 | do { | |||
3807 | if (const Operator *U = dyn_cast<Operator>(V)) { | |||
3808 | // If we find a ptrtoint, we can transfer control back to the | |||
3809 | // regular getUnderlyingObjectFromInt. | |||
3810 | if (U->getOpcode() == Instruction::PtrToInt) | |||
3811 | return U->getOperand(0); | |||
3812 | // If we find an add of a constant, a multiplied value, or a phi, it's | |||
3813 | // likely that the other operand will lead us to the base | |||
3814 | // object. We don't have to worry about the case where the | |||
3815 | // object address is somehow being computed by the multiply, | |||
3816 | // because our callers only care when the result is an | |||
3817 | // identifiable object. | |||
3818 | if (U->getOpcode() != Instruction::Add || | |||
3819 | (!isa<ConstantInt>(U->getOperand(1)) && | |||
3820 | Operator::getOpcode(U->getOperand(1)) != Instruction::Mul && | |||
3821 | !isa<PHINode>(U->getOperand(1)))) | |||
3822 | return V; | |||
3823 | V = U->getOperand(0); | |||
3824 | } else { | |||
3825 | return V; | |||
3826 | } | |||
3827 | assert(V->getType()->isIntegerTy() && "Unexpected operand type!")((V->getType()->isIntegerTy() && "Unexpected operand type!" ) ? static_cast<void> (0) : __assert_fail ("V->getType()->isIntegerTy() && \"Unexpected operand type!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3827, __PRETTY_FUNCTION__)); | |||
3828 | } while (true); | |||
3829 | } | |||
3830 | ||||
3831 | /// This is a wrapper around GetUnderlyingObjects and adds support for basic | |||
3832 | /// ptrtoint+arithmetic+inttoptr sequences. | |||
3833 | /// It returns false if unidentified object is found in GetUnderlyingObjects. | |||
3834 | bool llvm::getUnderlyingObjectsForCodeGen(const Value *V, | |||
3835 | SmallVectorImpl<Value *> &Objects, | |||
3836 | const DataLayout &DL) { | |||
3837 | SmallPtrSet<const Value *, 16> Visited; | |||
3838 | SmallVector<const Value *, 4> Working(1, V); | |||
3839 | do { | |||
3840 | V = Working.pop_back_val(); | |||
3841 | ||||
3842 | SmallVector<const Value *, 4> Objs; | |||
3843 | GetUnderlyingObjects(V, Objs, DL); | |||
3844 | ||||
3845 | for (const Value *V : Objs) { | |||
3846 | if (!Visited.insert(V).second) | |||
3847 | continue; | |||
3848 | if (Operator::getOpcode(V) == Instruction::IntToPtr) { | |||
3849 | const Value *O = | |||
3850 | getUnderlyingObjectFromInt(cast<User>(V)->getOperand(0)); | |||
3851 | if (O->getType()->isPointerTy()) { | |||
3852 | Working.push_back(O); | |||
3853 | continue; | |||
3854 | } | |||
3855 | } | |||
3856 | // If GetUnderlyingObjects fails to find an identifiable object, | |||
3857 | // getUnderlyingObjectsForCodeGen also fails for safety. | |||
3858 | if (!isIdentifiedObject(V)) { | |||
3859 | Objects.clear(); | |||
3860 | return false; | |||
3861 | } | |||
3862 | Objects.push_back(const_cast<Value *>(V)); | |||
3863 | } | |||
3864 | } while (!Working.empty()); | |||
3865 | return true; | |||
3866 | } | |||
3867 | ||||
3868 | /// Return true if the only users of this pointer are lifetime markers. | |||
3869 | bool llvm::onlyUsedByLifetimeMarkers(const Value *V) { | |||
3870 | for (const User *U : V->users()) { | |||
3871 | const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U); | |||
3872 | if (!II) return false; | |||
3873 | ||||
3874 | if (!II->isLifetimeStartOrEnd()) | |||
3875 | return false; | |||
3876 | } | |||
3877 | return true; | |||
3878 | } | |||
3879 | ||||
3880 | bool llvm::mustSuppressSpeculation(const LoadInst &LI) { | |||
3881 | if (!LI.isUnordered()) | |||
3882 | return true; | |||
3883 | const Function &F = *LI.getFunction(); | |||
3884 | // Speculative load may create a race that did not exist in the source. | |||
3885 | return F.hasFnAttribute(Attribute::SanitizeThread) || | |||
3886 | // Speculative load may load data from dirty regions. | |||
3887 | F.hasFnAttribute(Attribute::SanitizeAddress) || | |||
3888 | F.hasFnAttribute(Attribute::SanitizeHWAddress); | |||
3889 | } | |||
3890 | ||||
3891 | ||||
3892 | bool llvm::isSafeToSpeculativelyExecute(const Value *V, | |||
3893 | const Instruction *CtxI, | |||
3894 | const DominatorTree *DT) { | |||
3895 | const Operator *Inst = dyn_cast<Operator>(V); | |||
3896 | if (!Inst) | |||
3897 | return false; | |||
3898 | ||||
3899 | for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i) | |||
3900 | if (Constant *C = dyn_cast<Constant>(Inst->getOperand(i))) | |||
3901 | if (C->canTrap()) | |||
3902 | return false; | |||
3903 | ||||
3904 | switch (Inst->getOpcode()) { | |||
3905 | default: | |||
3906 | return true; | |||
3907 | case Instruction::UDiv: | |||
3908 | case Instruction::URem: { | |||
3909 | // x / y is undefined if y == 0. | |||
3910 | const APInt *V; | |||
3911 | if (match(Inst->getOperand(1), m_APInt(V))) | |||
3912 | return *V != 0; | |||
3913 | return false; | |||
3914 | } | |||
3915 | case Instruction::SDiv: | |||
3916 | case Instruction::SRem: { | |||
3917 | // x / y is undefined if y == 0 or x == INT_MIN and y == -1 | |||
3918 | const APInt *Numerator, *Denominator; | |||
3919 | if (!match(Inst->getOperand(1), m_APInt(Denominator))) | |||
3920 | return false; | |||
3921 | // We cannot hoist this division if the denominator is 0. | |||
3922 | if (*Denominator == 0) | |||
3923 | return false; | |||
3924 | // It's safe to hoist if the denominator is not 0 or -1. | |||
3925 | if (*Denominator != -1) | |||
3926 | return true; | |||
3927 | // At this point we know that the denominator is -1. It is safe to hoist as | |||
3928 | // long we know that the numerator is not INT_MIN. | |||
3929 | if (match(Inst->getOperand(0), m_APInt(Numerator))) | |||
3930 | return !Numerator->isMinSignedValue(); | |||
3931 | // The numerator *might* be MinSignedValue. | |||
3932 | return false; | |||
3933 | } | |||
3934 | case Instruction::Load: { | |||
3935 | const LoadInst *LI = cast<LoadInst>(Inst); | |||
3936 | if (mustSuppressSpeculation(*LI)) | |||
3937 | return false; | |||
3938 | const DataLayout &DL = LI->getModule()->getDataLayout(); | |||
3939 | return isDereferenceableAndAlignedPointer(LI->getPointerOperand(), | |||
3940 | LI->getType(), LI->getAlignment(), | |||
3941 | DL, CtxI, DT); | |||
3942 | } | |||
3943 | case Instruction::Call: { | |||
3944 | auto *CI = cast<const CallInst>(Inst); | |||
3945 | const Function *Callee = CI->getCalledFunction(); | |||
3946 | ||||
3947 | // The called function could have undefined behavior or side-effects, even | |||
3948 | // if marked readnone nounwind. | |||
3949 | return Callee && Callee->isSpeculatable(); | |||
3950 | } | |||
3951 | case Instruction::VAArg: | |||
3952 | case Instruction::Alloca: | |||
3953 | case Instruction::Invoke: | |||
3954 | case Instruction::CallBr: | |||
3955 | case Instruction::PHI: | |||
3956 | case Instruction::Store: | |||
3957 | case Instruction::Ret: | |||
3958 | case Instruction::Br: | |||
3959 | case Instruction::IndirectBr: | |||
3960 | case Instruction::Switch: | |||
3961 | case Instruction::Unreachable: | |||
3962 | case Instruction::Fence: | |||
3963 | case Instruction::AtomicRMW: | |||
3964 | case Instruction::AtomicCmpXchg: | |||
3965 | case Instruction::LandingPad: | |||
3966 | case Instruction::Resume: | |||
3967 | case Instruction::CatchSwitch: | |||
3968 | case Instruction::CatchPad: | |||
3969 | case Instruction::CatchRet: | |||
3970 | case Instruction::CleanupPad: | |||
3971 | case Instruction::CleanupRet: | |||
3972 | return false; // Misc instructions which have effects | |||
3973 | } | |||
3974 | } | |||
3975 | ||||
3976 | bool llvm::mayBeMemoryDependent(const Instruction &I) { | |||
3977 | return I.mayReadOrWriteMemory() || !isSafeToSpeculativelyExecute(&I); | |||
3978 | } | |||
3979 | ||||
3980 | /// Convert ConstantRange OverflowResult into ValueTracking OverflowResult. | |||
3981 | static OverflowResult mapOverflowResult(ConstantRange::OverflowResult OR) { | |||
3982 | switch (OR) { | |||
3983 | case ConstantRange::OverflowResult::MayOverflow: | |||
3984 | return OverflowResult::MayOverflow; | |||
3985 | case ConstantRange::OverflowResult::AlwaysOverflowsLow: | |||
3986 | return OverflowResult::AlwaysOverflowsLow; | |||
3987 | case ConstantRange::OverflowResult::AlwaysOverflowsHigh: | |||
3988 | return OverflowResult::AlwaysOverflowsHigh; | |||
3989 | case ConstantRange::OverflowResult::NeverOverflows: | |||
3990 | return OverflowResult::NeverOverflows; | |||
3991 | } | |||
3992 | llvm_unreachable("Unknown OverflowResult")::llvm::llvm_unreachable_internal("Unknown OverflowResult", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 3992); | |||
3993 | } | |||
3994 | ||||
3995 | /// Combine constant ranges from computeConstantRange() and computeKnownBits(). | |||
3996 | static ConstantRange computeConstantRangeIncludingKnownBits( | |||
3997 | const Value *V, bool ForSigned, const DataLayout &DL, unsigned Depth, | |||
3998 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
3999 | OptimizationRemarkEmitter *ORE = nullptr, bool UseInstrInfo = true) { | |||
4000 | KnownBits Known = computeKnownBits( | |||
4001 | V, DL, Depth, AC, CxtI, DT, ORE, UseInstrInfo); | |||
4002 | ConstantRange CR1 = ConstantRange::fromKnownBits(Known, ForSigned); | |||
4003 | ConstantRange CR2 = computeConstantRange(V, UseInstrInfo); | |||
4004 | ConstantRange::PreferredRangeType RangeType = | |||
4005 | ForSigned ? ConstantRange::Signed : ConstantRange::Unsigned; | |||
4006 | return CR1.intersectWith(CR2, RangeType); | |||
4007 | } | |||
4008 | ||||
4009 | OverflowResult llvm::computeOverflowForUnsignedMul( | |||
4010 | const Value *LHS, const Value *RHS, const DataLayout &DL, | |||
4011 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
4012 | bool UseInstrInfo) { | |||
4013 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4014 | nullptr, UseInstrInfo); | |||
4015 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4016 | nullptr, UseInstrInfo); | |||
4017 | ConstantRange LHSRange = ConstantRange::fromKnownBits(LHSKnown, false); | |||
4018 | ConstantRange RHSRange = ConstantRange::fromKnownBits(RHSKnown, false); | |||
4019 | return mapOverflowResult(LHSRange.unsignedMulMayOverflow(RHSRange)); | |||
4020 | } | |||
4021 | ||||
4022 | OverflowResult | |||
4023 | llvm::computeOverflowForSignedMul(const Value *LHS, const Value *RHS, | |||
4024 | const DataLayout &DL, AssumptionCache *AC, | |||
4025 | const Instruction *CxtI, | |||
4026 | const DominatorTree *DT, bool UseInstrInfo) { | |||
4027 | // Multiplying n * m significant bits yields a result of n + m significant | |||
4028 | // bits. If the total number of significant bits does not exceed the | |||
4029 | // result bit width (minus 1), there is no overflow. | |||
4030 | // This means if we have enough leading sign bits in the operands | |||
4031 | // we can guarantee that the result does not overflow. | |||
4032 | // Ref: "Hacker's Delight" by Henry Warren | |||
4033 | unsigned BitWidth = LHS->getType()->getScalarSizeInBits(); | |||
4034 | ||||
4035 | // Note that underestimating the number of sign bits gives a more | |||
4036 | // conservative answer. | |||
4037 | unsigned SignBits = ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) + | |||
4038 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT); | |||
4039 | ||||
4040 | // First handle the easy case: if we have enough sign bits there's | |||
4041 | // definitely no overflow. | |||
4042 | if (SignBits > BitWidth + 1) | |||
4043 | return OverflowResult::NeverOverflows; | |||
4044 | ||||
4045 | // There are two ambiguous cases where there can be no overflow: | |||
4046 | // SignBits == BitWidth + 1 and | |||
4047 | // SignBits == BitWidth | |||
4048 | // The second case is difficult to check, therefore we only handle the | |||
4049 | // first case. | |||
4050 | if (SignBits == BitWidth + 1) { | |||
4051 | // It overflows only when both arguments are negative and the true | |||
4052 | // product is exactly the minimum negative number. | |||
4053 | // E.g. mul i16 with 17 sign bits: 0xff00 * 0xff80 = 0x8000 | |||
4054 | // For simplicity we just check if at least one side is not negative. | |||
4055 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4056 | nullptr, UseInstrInfo); | |||
4057 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4058 | nullptr, UseInstrInfo); | |||
4059 | if (LHSKnown.isNonNegative() || RHSKnown.isNonNegative()) | |||
4060 | return OverflowResult::NeverOverflows; | |||
4061 | } | |||
4062 | return OverflowResult::MayOverflow; | |||
4063 | } | |||
4064 | ||||
4065 | OverflowResult llvm::computeOverflowForUnsignedAdd( | |||
4066 | const Value *LHS, const Value *RHS, const DataLayout &DL, | |||
4067 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, | |||
4068 | bool UseInstrInfo) { | |||
4069 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4070 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4071 | nullptr, UseInstrInfo); | |||
4072 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4073 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, | |||
4074 | nullptr, UseInstrInfo); | |||
4075 | return mapOverflowResult(LHSRange.unsignedAddMayOverflow(RHSRange)); | |||
4076 | } | |||
4077 | ||||
4078 | static OverflowResult computeOverflowForSignedAdd(const Value *LHS, | |||
4079 | const Value *RHS, | |||
4080 | const AddOperator *Add, | |||
4081 | const DataLayout &DL, | |||
4082 | AssumptionCache *AC, | |||
4083 | const Instruction *CxtI, | |||
4084 | const DominatorTree *DT) { | |||
4085 | if (Add && Add->hasNoSignedWrap()) { | |||
4086 | return OverflowResult::NeverOverflows; | |||
4087 | } | |||
4088 | ||||
4089 | // If LHS and RHS each have at least two sign bits, the addition will look | |||
4090 | // like | |||
4091 | // | |||
4092 | // XX..... + | |||
4093 | // YY..... | |||
4094 | // | |||
4095 | // If the carry into the most significant position is 0, X and Y can't both | |||
4096 | // be 1 and therefore the carry out of the addition is also 0. | |||
4097 | // | |||
4098 | // If the carry into the most significant position is 1, X and Y can't both | |||
4099 | // be 0 and therefore the carry out of the addition is also 1. | |||
4100 | // | |||
4101 | // Since the carry into the most significant position is always equal to | |||
4102 | // the carry out of the addition, there is no signed overflow. | |||
4103 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && | |||
4104 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) | |||
4105 | return OverflowResult::NeverOverflows; | |||
4106 | ||||
4107 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4108 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4109 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4110 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4111 | OverflowResult OR = | |||
4112 | mapOverflowResult(LHSRange.signedAddMayOverflow(RHSRange)); | |||
4113 | if (OR != OverflowResult::MayOverflow) | |||
4114 | return OR; | |||
4115 | ||||
4116 | // The remaining code needs Add to be available. Early returns if not so. | |||
4117 | if (!Add) | |||
4118 | return OverflowResult::MayOverflow; | |||
4119 | ||||
4120 | // If the sign of Add is the same as at least one of the operands, this add | |||
4121 | // CANNOT overflow. If this can be determined from the known bits of the | |||
4122 | // operands the above signedAddMayOverflow() check will have already done so. | |||
4123 | // The only other way to improve on the known bits is from an assumption, so | |||
4124 | // call computeKnownBitsFromAssume() directly. | |||
4125 | bool LHSOrRHSKnownNonNegative = | |||
4126 | (LHSRange.isAllNonNegative() || RHSRange.isAllNonNegative()); | |||
4127 | bool LHSOrRHSKnownNegative = | |||
4128 | (LHSRange.isAllNegative() || RHSRange.isAllNegative()); | |||
4129 | if (LHSOrRHSKnownNonNegative || LHSOrRHSKnownNegative) { | |||
4130 | KnownBits AddKnown(LHSRange.getBitWidth()); | |||
4131 | computeKnownBitsFromAssume( | |||
4132 | Add, AddKnown, /*Depth=*/0, Query(DL, AC, CxtI, DT, true)); | |||
4133 | if ((AddKnown.isNonNegative() && LHSOrRHSKnownNonNegative) || | |||
4134 | (AddKnown.isNegative() && LHSOrRHSKnownNegative)) | |||
4135 | return OverflowResult::NeverOverflows; | |||
4136 | } | |||
4137 | ||||
4138 | return OverflowResult::MayOverflow; | |||
4139 | } | |||
4140 | ||||
4141 | OverflowResult llvm::computeOverflowForUnsignedSub(const Value *LHS, | |||
4142 | const Value *RHS, | |||
4143 | const DataLayout &DL, | |||
4144 | AssumptionCache *AC, | |||
4145 | const Instruction *CxtI, | |||
4146 | const DominatorTree *DT) { | |||
4147 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4148 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4149 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4150 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4151 | return mapOverflowResult(LHSRange.unsignedSubMayOverflow(RHSRange)); | |||
4152 | } | |||
4153 | ||||
4154 | OverflowResult llvm::computeOverflowForSignedSub(const Value *LHS, | |||
4155 | const Value *RHS, | |||
4156 | const DataLayout &DL, | |||
4157 | AssumptionCache *AC, | |||
4158 | const Instruction *CxtI, | |||
4159 | const DominatorTree *DT) { | |||
4160 | // If LHS and RHS each have at least two sign bits, the subtraction | |||
4161 | // cannot overflow. | |||
4162 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && | |||
4163 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) | |||
4164 | return OverflowResult::NeverOverflows; | |||
4165 | ||||
4166 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( | |||
4167 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4168 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( | |||
4169 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); | |||
4170 | return mapOverflowResult(LHSRange.signedSubMayOverflow(RHSRange)); | |||
4171 | } | |||
4172 | ||||
4173 | bool llvm::isOverflowIntrinsicNoWrap(const WithOverflowInst *WO, | |||
4174 | const DominatorTree &DT) { | |||
4175 | SmallVector<const BranchInst *, 2> GuardingBranches; | |||
4176 | SmallVector<const ExtractValueInst *, 2> Results; | |||
4177 | ||||
4178 | for (const User *U : WO->users()) { | |||
4179 | if (const auto *EVI = dyn_cast<ExtractValueInst>(U)) { | |||
4180 | assert(EVI->getNumIndices() == 1 && "Obvious from CI's type")((EVI->getNumIndices() == 1 && "Obvious from CI's type" ) ? static_cast<void> (0) : __assert_fail ("EVI->getNumIndices() == 1 && \"Obvious from CI's type\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 4180, __PRETTY_FUNCTION__)); | |||
4181 | ||||
4182 | if (EVI->getIndices()[0] == 0) | |||
4183 | Results.push_back(EVI); | |||
4184 | else { | |||
4185 | assert(EVI->getIndices()[0] == 1 && "Obvious from CI's type")((EVI->getIndices()[0] == 1 && "Obvious from CI's type" ) ? static_cast<void> (0) : __assert_fail ("EVI->getIndices()[0] == 1 && \"Obvious from CI's type\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 4185, __PRETTY_FUNCTION__)); | |||
4186 | ||||
4187 | for (const auto *U : EVI->users()) | |||
4188 | if (const auto *B = dyn_cast<BranchInst>(U)) { | |||
4189 | assert(B->isConditional() && "How else is it using an i1?")((B->isConditional() && "How else is it using an i1?" ) ? static_cast<void> (0) : __assert_fail ("B->isConditional() && \"How else is it using an i1?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 4189, __PRETTY_FUNCTION__)); | |||
4190 | GuardingBranches.push_back(B); | |||
4191 | } | |||
4192 | } | |||
4193 | } else { | |||
4194 | // We are using the aggregate directly in a way we don't want to analyze | |||
4195 | // here (storing it to a global, say). | |||
4196 | return false; | |||
4197 | } | |||
4198 | } | |||
4199 | ||||
4200 | auto AllUsesGuardedByBranch = [&](const BranchInst *BI) { | |||
4201 | BasicBlockEdge NoWrapEdge(BI->getParent(), BI->getSuccessor(1)); | |||
4202 | if (!NoWrapEdge.isSingleEdge()) | |||
4203 | return false; | |||
4204 | ||||
4205 | // Check if all users of the add are provably no-wrap. | |||
4206 | for (const auto *Result : Results) { | |||
4207 | // If the extractvalue itself is not executed on overflow, the we don't | |||
4208 | // need to check each use separately, since domination is transitive. | |||
4209 | if (DT.dominates(NoWrapEdge, Result->getParent())) | |||
4210 | continue; | |||
4211 | ||||
4212 | for (auto &RU : Result->uses()) | |||
4213 | if (!DT.dominates(NoWrapEdge, RU)) | |||
4214 | return false; | |||
4215 | } | |||
4216 | ||||
4217 | return true; | |||
4218 | }; | |||
4219 | ||||
4220 | return llvm::any_of(GuardingBranches, AllUsesGuardedByBranch); | |||
4221 | } | |||
4222 | ||||
4223 | ||||
4224 | OverflowResult llvm::computeOverflowForSignedAdd(const AddOperator *Add, | |||
4225 | const DataLayout &DL, | |||
4226 | AssumptionCache *AC, | |||
4227 | const Instruction *CxtI, | |||
4228 | const DominatorTree *DT) { | |||
4229 | return ::computeOverflowForSignedAdd(Add->getOperand(0), Add->getOperand(1), | |||
4230 | Add, DL, AC, CxtI, DT); | |||
4231 | } | |||
4232 | ||||
4233 | OverflowResult llvm::computeOverflowForSignedAdd(const Value *LHS, | |||
4234 | const Value *RHS, | |||
4235 | const DataLayout &DL, | |||
4236 | AssumptionCache *AC, | |||
4237 | const Instruction *CxtI, | |||
4238 | const DominatorTree *DT) { | |||
4239 | return ::computeOverflowForSignedAdd(LHS, RHS, nullptr, DL, AC, CxtI, DT); | |||
4240 | } | |||
4241 | ||||
4242 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const Instruction *I) { | |||
4243 | // Note: An atomic operation isn't guaranteed to return in a reasonable amount | |||
4244 | // of time because it's possible for another thread to interfere with it for an | |||
4245 | // arbitrary length of time, but programs aren't allowed to rely on that. | |||
4246 | ||||
4247 | // If there is no successor, then execution can't transfer to it. | |||
4248 | if (const auto *CRI = dyn_cast<CleanupReturnInst>(I)) | |||
4249 | return !CRI->unwindsToCaller(); | |||
4250 | if (const auto *CatchSwitch = dyn_cast<CatchSwitchInst>(I)) | |||
4251 | return !CatchSwitch->unwindsToCaller(); | |||
4252 | if (isa<ResumeInst>(I)) | |||
4253 | return false; | |||
4254 | if (isa<ReturnInst>(I)) | |||
4255 | return false; | |||
4256 | if (isa<UnreachableInst>(I)) | |||
4257 | return false; | |||
4258 | ||||
4259 | // Calls can throw, or contain an infinite loop, or kill the process. | |||
4260 | if (auto CS = ImmutableCallSite(I)) { | |||
4261 | // Call sites that throw have implicit non-local control flow. | |||
4262 | if (!CS.doesNotThrow()) | |||
4263 | return false; | |||
4264 | ||||
4265 | // A function which doens't throw and has "willreturn" attribute will | |||
4266 | // always return. | |||
4267 | if (CS.hasFnAttr(Attribute::WillReturn)) | |||
4268 | return true; | |||
4269 | ||||
4270 | // Non-throwing call sites can loop infinitely, call exit/pthread_exit | |||
4271 | // etc. and thus not return. However, LLVM already assumes that | |||
4272 | // | |||
4273 | // - Thread exiting actions are modeled as writes to memory invisible to | |||
4274 | // the program. | |||
4275 | // | |||
4276 | // - Loops that don't have side effects (side effects are volatile/atomic | |||
4277 | // stores and IO) always terminate (see http://llvm.org/PR965). | |||
4278 | // Furthermore IO itself is also modeled as writes to memory invisible to | |||
4279 | // the program. | |||
4280 | // | |||
4281 | // We rely on those assumptions here, and use the memory effects of the call | |||
4282 | // target as a proxy for checking that it always returns. | |||
4283 | ||||
4284 | // FIXME: This isn't aggressive enough; a call which only writes to a global | |||
4285 | // is guaranteed to return. | |||
4286 | return CS.onlyReadsMemory() || CS.onlyAccessesArgMemory(); | |||
4287 | } | |||
4288 | ||||
4289 | // Other instructions return normally. | |||
4290 | return true; | |||
4291 | } | |||
4292 | ||||
4293 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB) { | |||
4294 | // TODO: This is slightly conservative for invoke instruction since exiting | |||
4295 | // via an exception *is* normal control for them. | |||
4296 | for (auto I = BB->begin(), E = BB->end(); I != E; ++I) | |||
4297 | if (!isGuaranteedToTransferExecutionToSuccessor(&*I)) | |||
4298 | return false; | |||
4299 | return true; | |||
4300 | } | |||
4301 | ||||
4302 | bool llvm::isGuaranteedToExecuteForEveryIteration(const Instruction *I, | |||
4303 | const Loop *L) { | |||
4304 | // The loop header is guaranteed to be executed for every iteration. | |||
4305 | // | |||
4306 | // FIXME: Relax this constraint to cover all basic blocks that are | |||
4307 | // guaranteed to be executed at every iteration. | |||
4308 | if (I->getParent() != L->getHeader()) return false; | |||
4309 | ||||
4310 | for (const Instruction &LI : *L->getHeader()) { | |||
4311 | if (&LI == I) return true; | |||
4312 | if (!isGuaranteedToTransferExecutionToSuccessor(&LI)) return false; | |||
4313 | } | |||
4314 | 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-10~svn372306/lib/Analysis/ValueTracking.cpp" , 4314); | |||
4315 | } | |||
4316 | ||||
4317 | bool llvm::propagatesFullPoison(const Instruction *I) { | |||
4318 | // TODO: This should include all instructions apart from phis, selects and | |||
4319 | // call-like instructions. | |||
4320 | switch (I->getOpcode()) { | |||
4321 | case Instruction::Add: | |||
4322 | case Instruction::Sub: | |||
4323 | case Instruction::Xor: | |||
4324 | case Instruction::Trunc: | |||
4325 | case Instruction::BitCast: | |||
4326 | case Instruction::AddrSpaceCast: | |||
4327 | case Instruction::Mul: | |||
4328 | case Instruction::Shl: | |||
4329 | case Instruction::GetElementPtr: | |||
4330 | // These operations all propagate poison unconditionally. Note that poison | |||
4331 | // is not any particular value, so xor or subtraction of poison with | |||
4332 | // itself still yields poison, not zero. | |||
4333 | return true; | |||
4334 | ||||
4335 | case Instruction::AShr: | |||
4336 | case Instruction::SExt: | |||
4337 | // For these operations, one bit of the input is replicated across | |||
4338 | // multiple output bits. A replicated poison bit is still poison. | |||
4339 | return true; | |||
4340 | ||||
4341 | case Instruction::ICmp: | |||
4342 | // Comparing poison with any value yields poison. This is why, for | |||
4343 | // instance, x s< (x +nsw 1) can be folded to true. | |||
4344 | return true; | |||
4345 | ||||
4346 | default: | |||
4347 | return false; | |||
4348 | } | |||
4349 | } | |||
4350 | ||||
4351 | const Value *llvm::getGuaranteedNonFullPoisonOp(const Instruction *I) { | |||
4352 | switch (I->getOpcode()) { | |||
4353 | case Instruction::Store: | |||
4354 | return cast<StoreInst>(I)->getPointerOperand(); | |||
4355 | ||||
4356 | case Instruction::Load: | |||
4357 | return cast<LoadInst>(I)->getPointerOperand(); | |||
4358 | ||||
4359 | case Instruction::AtomicCmpXchg: | |||
4360 | return cast<AtomicCmpXchgInst>(I)->getPointerOperand(); | |||
4361 | ||||
4362 | case Instruction::AtomicRMW: | |||
4363 | return cast<AtomicRMWInst>(I)->getPointerOperand(); | |||
4364 | ||||
4365 | case Instruction::UDiv: | |||
4366 | case Instruction::SDiv: | |||
4367 | case Instruction::URem: | |||
4368 | case Instruction::SRem: | |||
4369 | return I->getOperand(1); | |||
4370 | ||||
4371 | default: | |||
4372 | // Note: It's really tempting to think that a conditional branch or | |||
4373 | // switch should be listed here, but that's incorrect. It's not | |||
4374 | // branching off of poison which is UB, it is executing a side effecting | |||
4375 | // instruction which follows the branch. | |||
4376 | return nullptr; | |||
4377 | } | |||
4378 | } | |||
4379 | ||||
4380 | bool llvm::mustTriggerUB(const Instruction *I, | |||
4381 | const SmallSet<const Value *, 16>& KnownPoison) { | |||
4382 | auto *NotPoison = getGuaranteedNonFullPoisonOp(I); | |||
4383 | return (NotPoison && KnownPoison.count(NotPoison)); | |||
4384 | } | |||
4385 | ||||
4386 | ||||
4387 | bool llvm::programUndefinedIfFullPoison(const Instruction *PoisonI) { | |||
4388 | // We currently only look for uses of poison values within the same basic | |||
4389 | // block, as that makes it easier to guarantee that the uses will be | |||
4390 | // executed given that PoisonI is executed. | |||
4391 | // | |||
4392 | // FIXME: Expand this to consider uses beyond the same basic block. To do | |||
4393 | // this, look out for the distinction between post-dominance and strong | |||
4394 | // post-dominance. | |||
4395 | const BasicBlock *BB = PoisonI->getParent(); | |||
4396 | ||||
4397 | // Set of instructions that we have proved will yield poison if PoisonI | |||
4398 | // does. | |||
4399 | SmallSet<const Value *, 16> YieldsPoison; | |||
4400 | SmallSet<const BasicBlock *, 4> Visited; | |||
4401 | YieldsPoison.insert(PoisonI); | |||
4402 | Visited.insert(PoisonI->getParent()); | |||
4403 | ||||
4404 | BasicBlock::const_iterator Begin = PoisonI->getIterator(), End = BB->end(); | |||
4405 | ||||
4406 | unsigned Iter = 0; | |||
4407 | while (Iter++ < MaxDepth) { | |||
4408 | for (auto &I : make_range(Begin, End)) { | |||
4409 | if (&I != PoisonI) { | |||
4410 | if (mustTriggerUB(&I, YieldsPoison)) | |||
4411 | return true; | |||
4412 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) | |||
4413 | return false; | |||
4414 | } | |||
4415 | ||||
4416 | // Mark poison that propagates from I through uses of I. | |||
4417 | if (YieldsPoison.count(&I)) { | |||
4418 | for (const User *User : I.users()) { | |||
4419 | const Instruction *UserI = cast<Instruction>(User); | |||
4420 | if (propagatesFullPoison(UserI)) | |||
4421 | YieldsPoison.insert(User); | |||
4422 | } | |||
4423 | } | |||
4424 | } | |||
4425 | ||||
4426 | if (auto *NextBB = BB->getSingleSuccessor()) { | |||
4427 | if (Visited.insert(NextBB).second) { | |||
4428 | BB = NextBB; | |||
4429 | Begin = BB->getFirstNonPHI()->getIterator(); | |||
4430 | End = BB->end(); | |||
4431 | continue; | |||
4432 | } | |||
4433 | } | |||
4434 | ||||
4435 | break; | |||
4436 | } | |||
4437 | return false; | |||
4438 | } | |||
4439 | ||||
4440 | static bool isKnownNonNaN(const Value *V, FastMathFlags FMF) { | |||
4441 | if (FMF.noNaNs()) | |||
4442 | return true; | |||
4443 | ||||
4444 | if (auto *C = dyn_cast<ConstantFP>(V)) | |||
4445 | return !C->isNaN(); | |||
4446 | ||||
4447 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { | |||
4448 | if (!C->getElementType()->isFloatingPointTy()) | |||
4449 | return false; | |||
4450 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { | |||
4451 | if (C->getElementAsAPFloat(I).isNaN()) | |||
4452 | return false; | |||
4453 | } | |||
4454 | return true; | |||
4455 | } | |||
4456 | ||||
4457 | return false; | |||
4458 | } | |||
4459 | ||||
4460 | static bool isKnownNonZero(const Value *V) { | |||
4461 | if (auto *C = dyn_cast<ConstantFP>(V)) | |||
4462 | return !C->isZero(); | |||
4463 | ||||
4464 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { | |||
4465 | if (!C->getElementType()->isFloatingPointTy()) | |||
4466 | return false; | |||
4467 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { | |||
4468 | if (C->getElementAsAPFloat(I).isZero()) | |||
4469 | return false; | |||
4470 | } | |||
4471 | return true; | |||
4472 | } | |||
4473 | ||||
4474 | return false; | |||
4475 | } | |||
4476 | ||||
4477 | /// Match clamp pattern for float types without care about NaNs or signed zeros. | |||
4478 | /// Given non-min/max outer cmp/select from the clamp pattern this | |||
4479 | /// function recognizes if it can be substitued by a "canonical" min/max | |||
4480 | /// pattern. | |||
4481 | static SelectPatternResult matchFastFloatClamp(CmpInst::Predicate Pred, | |||
4482 | Value *CmpLHS, Value *CmpRHS, | |||
4483 | Value *TrueVal, Value *FalseVal, | |||
4484 | Value *&LHS, Value *&RHS) { | |||
4485 | // Try to match | |||
4486 | // X < C1 ? C1 : Min(X, C2) --> Max(C1, Min(X, C2)) | |||
4487 | // X > C1 ? C1 : Max(X, C2) --> Min(C1, Max(X, C2)) | |||
4488 | // and return description of the outer Max/Min. | |||
4489 | ||||
4490 | // First, check if select has inverse order: | |||
4491 | if (CmpRHS == FalseVal) { | |||
4492 | std::swap(TrueVal, FalseVal); | |||
4493 | Pred = CmpInst::getInversePredicate(Pred); | |||
4494 | } | |||
4495 | ||||
4496 | // Assume success now. If there's no match, callers should not use these anyway. | |||
4497 | LHS = TrueVal; | |||
4498 | RHS = FalseVal; | |||
4499 | ||||
4500 | const APFloat *FC1; | |||
4501 | if (CmpRHS != TrueVal || !match(CmpRHS, m_APFloat(FC1)) || !FC1->isFinite()) | |||
4502 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4503 | ||||
4504 | const APFloat *FC2; | |||
4505 | switch (Pred) { | |||
4506 | case CmpInst::FCMP_OLT: | |||
4507 | case CmpInst::FCMP_OLE: | |||
4508 | case CmpInst::FCMP_ULT: | |||
4509 | case CmpInst::FCMP_ULE: | |||
4510 | if (match(FalseVal, | |||
4511 | m_CombineOr(m_OrdFMin(m_Specific(CmpLHS), m_APFloat(FC2)), | |||
4512 | m_UnordFMin(m_Specific(CmpLHS), m_APFloat(FC2)))) && | |||
4513 | FC1->compare(*FC2) == APFloat::cmpResult::cmpLessThan) | |||
4514 | return {SPF_FMAXNUM, SPNB_RETURNS_ANY, false}; | |||
4515 | break; | |||
4516 | case CmpInst::FCMP_OGT: | |||
4517 | case CmpInst::FCMP_OGE: | |||
4518 | case CmpInst::FCMP_UGT: | |||
4519 | case CmpInst::FCMP_UGE: | |||
4520 | if (match(FalseVal, | |||
4521 | m_CombineOr(m_OrdFMax(m_Specific(CmpLHS), m_APFloat(FC2)), | |||
4522 | m_UnordFMax(m_Specific(CmpLHS), m_APFloat(FC2)))) && | |||
4523 | FC1->compare(*FC2) == APFloat::cmpResult::cmpGreaterThan) | |||
4524 | return {SPF_FMINNUM, SPNB_RETURNS_ANY, false}; | |||
4525 | break; | |||
4526 | default: | |||
4527 | break; | |||
4528 | } | |||
4529 | ||||
4530 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4531 | } | |||
4532 | ||||
4533 | /// Recognize variations of: | |||
4534 | /// CLAMP(v,l,h) ==> ((v) < (l) ? (l) : ((v) > (h) ? (h) : (v))) | |||
4535 | static SelectPatternResult matchClamp(CmpInst::Predicate Pred, | |||
4536 | Value *CmpLHS, Value *CmpRHS, | |||
4537 | Value *TrueVal, Value *FalseVal) { | |||
4538 | // Swap the select operands and predicate to match the patterns below. | |||
4539 | if (CmpRHS != TrueVal) { | |||
4540 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
4541 | std::swap(TrueVal, FalseVal); | |||
4542 | } | |||
4543 | const APInt *C1; | |||
4544 | if (CmpRHS == TrueVal && match(CmpRHS, m_APInt(C1))) { | |||
4545 | const APInt *C2; | |||
4546 | // (X <s C1) ? C1 : SMIN(X, C2) ==> SMAX(SMIN(X, C2), C1) | |||
4547 | if (match(FalseVal, m_SMin(m_Specific(CmpLHS), m_APInt(C2))) && | |||
4548 | C1->slt(*C2) && Pred == CmpInst::ICMP_SLT) | |||
4549 | return {SPF_SMAX, SPNB_NA, false}; | |||
4550 | ||||
4551 | // (X >s C1) ? C1 : SMAX(X, C2) ==> SMIN(SMAX(X, C2), C1) | |||
4552 | if (match(FalseVal, m_SMax(m_Specific(CmpLHS), m_APInt(C2))) && | |||
4553 | C1->sgt(*C2) && Pred == CmpInst::ICMP_SGT) | |||
4554 | return {SPF_SMIN, SPNB_NA, false}; | |||
4555 | ||||
4556 | // (X <u C1) ? C1 : UMIN(X, C2) ==> UMAX(UMIN(X, C2), C1) | |||
4557 | if (match(FalseVal, m_UMin(m_Specific(CmpLHS), m_APInt(C2))) && | |||
4558 | C1->ult(*C2) && Pred == CmpInst::ICMP_ULT) | |||
4559 | return {SPF_UMAX, SPNB_NA, false}; | |||
4560 | ||||
4561 | // (X >u C1) ? C1 : UMAX(X, C2) ==> UMIN(UMAX(X, C2), C1) | |||
4562 | if (match(FalseVal, m_UMax(m_Specific(CmpLHS), m_APInt(C2))) && | |||
4563 | C1->ugt(*C2) && Pred == CmpInst::ICMP_UGT) | |||
4564 | return {SPF_UMIN, SPNB_NA, false}; | |||
4565 | } | |||
4566 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4567 | } | |||
4568 | ||||
4569 | /// Recognize variations of: | |||
4570 | /// a < c ? min(a,b) : min(b,c) ==> min(min(a,b),min(b,c)) | |||
4571 | static SelectPatternResult matchMinMaxOfMinMax(CmpInst::Predicate Pred, | |||
4572 | Value *CmpLHS, Value *CmpRHS, | |||
4573 | Value *TVal, Value *FVal, | |||
4574 | unsigned Depth) { | |||
4575 | // TODO: Allow FP min/max with nnan/nsz. | |||
4576 | assert(CmpInst::isIntPredicate(Pred) && "Expected integer comparison")((CmpInst::isIntPredicate(Pred) && "Expected integer comparison" ) ? static_cast<void> (0) : __assert_fail ("CmpInst::isIntPredicate(Pred) && \"Expected integer comparison\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 4576, __PRETTY_FUNCTION__)); | |||
4577 | ||||
4578 | Value *A, *B; | |||
4579 | SelectPatternResult L = matchSelectPattern(TVal, A, B, nullptr, Depth + 1); | |||
4580 | if (!SelectPatternResult::isMinOrMax(L.Flavor)) | |||
4581 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4582 | ||||
4583 | Value *C, *D; | |||
4584 | SelectPatternResult R = matchSelectPattern(FVal, C, D, nullptr, Depth + 1); | |||
4585 | if (L.Flavor != R.Flavor) | |||
4586 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4587 | ||||
4588 | // We have something like: x Pred y ? min(a, b) : min(c, d). | |||
4589 | // Try to match the compare to the min/max operations of the select operands. | |||
4590 | // First, make sure we have the right compare predicate. | |||
4591 | switch (L.Flavor) { | |||
4592 | case SPF_SMIN: | |||
4593 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) { | |||
4594 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
4595 | std::swap(CmpLHS, CmpRHS); | |||
4596 | } | |||
4597 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) | |||
4598 | break; | |||
4599 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4600 | case SPF_SMAX: | |||
4601 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) { | |||
4602 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
4603 | std::swap(CmpLHS, CmpRHS); | |||
4604 | } | |||
4605 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) | |||
4606 | break; | |||
4607 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4608 | case SPF_UMIN: | |||
4609 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) { | |||
4610 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
4611 | std::swap(CmpLHS, CmpRHS); | |||
4612 | } | |||
4613 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) | |||
4614 | break; | |||
4615 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4616 | case SPF_UMAX: | |||
4617 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { | |||
4618 | Pred = ICmpInst::getSwappedPredicate(Pred); | |||
4619 | std::swap(CmpLHS, CmpRHS); | |||
4620 | } | |||
4621 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) | |||
4622 | break; | |||
4623 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4624 | default: | |||
4625 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4626 | } | |||
4627 | ||||
4628 | // If there is a common operand in the already matched min/max and the other | |||
4629 | // min/max operands match the compare operands (either directly or inverted), | |||
4630 | // then this is min/max of the same flavor. | |||
4631 | ||||
4632 | // a pred c ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) | |||
4633 | // ~c pred ~a ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) | |||
4634 | if (D == B) { | |||
4635 | if ((CmpLHS == A && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && | |||
4636 | match(A, m_Not(m_Specific(CmpRHS))))) | |||
4637 | return {L.Flavor, SPNB_NA, false}; | |||
4638 | } | |||
4639 | // a pred d ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) | |||
4640 | // ~d pred ~a ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) | |||
4641 | if (C == B) { | |||
4642 | if ((CmpLHS == A && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && | |||
4643 | match(A, m_Not(m_Specific(CmpRHS))))) | |||
4644 | return {L.Flavor, SPNB_NA, false}; | |||
4645 | } | |||
4646 | // b pred c ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) | |||
4647 | // ~c pred ~b ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) | |||
4648 | if (D == A) { | |||
4649 | if ((CmpLHS == B && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && | |||
4650 | match(B, m_Not(m_Specific(CmpRHS))))) | |||
4651 | return {L.Flavor, SPNB_NA, false}; | |||
4652 | } | |||
4653 | // b pred d ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) | |||
4654 | // ~d pred ~b ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) | |||
4655 | if (C == A) { | |||
4656 | if ((CmpLHS == B && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && | |||
4657 | match(B, m_Not(m_Specific(CmpRHS))))) | |||
4658 | return {L.Flavor, SPNB_NA, false}; | |||
4659 | } | |||
4660 | ||||
4661 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4662 | } | |||
4663 | ||||
4664 | /// Match non-obvious integer minimum and maximum sequences. | |||
4665 | static SelectPatternResult matchMinMax(CmpInst::Predicate Pred, | |||
4666 | Value *CmpLHS, Value *CmpRHS, | |||
4667 | Value *TrueVal, Value *FalseVal, | |||
4668 | Value *&LHS, Value *&RHS, | |||
4669 | unsigned Depth) { | |||
4670 | // Assume success. If there's no match, callers should not use these anyway. | |||
4671 | LHS = TrueVal; | |||
4672 | RHS = FalseVal; | |||
4673 | ||||
4674 | SelectPatternResult SPR = matchClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal); | |||
4675 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) | |||
4676 | return SPR; | |||
4677 | ||||
4678 | SPR = matchMinMaxOfMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, Depth); | |||
4679 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) | |||
4680 | return SPR; | |||
4681 | ||||
4682 | if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT) | |||
4683 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4684 | ||||
4685 | // Z = X -nsw Y | |||
4686 | // (X >s Y) ? 0 : Z ==> (Z >s 0) ? 0 : Z ==> SMIN(Z, 0) | |||
4687 | // (X <s Y) ? 0 : Z ==> (Z <s 0) ? 0 : Z ==> SMAX(Z, 0) | |||
4688 | if (match(TrueVal, m_Zero()) && | |||
4689 | match(FalseVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS)))) | |||
4690 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false}; | |||
4691 | ||||
4692 | // Z = X -nsw Y | |||
4693 | // (X >s Y) ? Z : 0 ==> (Z >s 0) ? Z : 0 ==> SMAX(Z, 0) | |||
4694 | // (X <s Y) ? Z : 0 ==> (Z <s 0) ? Z : 0 ==> SMIN(Z, 0) | |||
4695 | if (match(FalseVal, m_Zero()) && | |||
4696 | match(TrueVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS)))) | |||
4697 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false}; | |||
4698 | ||||
4699 | const APInt *C1; | |||
4700 | if (!match(CmpRHS, m_APInt(C1))) | |||
4701 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4702 | ||||
4703 | // An unsigned min/max can be written with a signed compare. | |||
4704 | const APInt *C2; | |||
4705 | if ((CmpLHS == TrueVal && match(FalseVal, m_APInt(C2))) || | |||
4706 | (CmpLHS == FalseVal && match(TrueVal, m_APInt(C2)))) { | |||
4707 | // Is the sign bit set? | |||
4708 | // (X <s 0) ? X : MAXVAL ==> (X >u MAXVAL) ? X : MAXVAL ==> UMAX | |||
4709 | // (X <s 0) ? MAXVAL : X ==> (X >u MAXVAL) ? MAXVAL : X ==> UMIN | |||
4710 | if (Pred == CmpInst::ICMP_SLT && C1->isNullValue() && | |||
4711 | C2->isMaxSignedValue()) | |||
4712 | return {CmpLHS == TrueVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; | |||
4713 | ||||
4714 | // Is the sign bit clear? | |||
4715 | // (X >s -1) ? MINVAL : X ==> (X <u MINVAL) ? MINVAL : X ==> UMAX | |||
4716 | // (X >s -1) ? X : MINVAL ==> (X <u MINVAL) ? X : MINVAL ==> UMIN | |||
4717 | if (Pred == CmpInst::ICMP_SGT && C1->isAllOnesValue() && | |||
4718 | C2->isMinSignedValue()) | |||
4719 | return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; | |||
4720 | } | |||
4721 | ||||
4722 | // Look through 'not' ops to find disguised signed min/max. | |||
4723 | // (X >s C) ? ~X : ~C ==> (~X <s ~C) ? ~X : ~C ==> SMIN(~X, ~C) | |||
4724 | // (X <s C) ? ~X : ~C ==> (~X >s ~C) ? ~X : ~C ==> SMAX(~X, ~C) | |||
4725 | if (match(TrueVal, m_Not(m_Specific(CmpLHS))) && | |||
4726 | match(FalseVal, m_APInt(C2)) && ~(*C1) == *C2) | |||
4727 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false}; | |||
4728 | ||||
4729 | // (X >s C) ? ~C : ~X ==> (~X <s ~C) ? ~C : ~X ==> SMAX(~C, ~X) | |||
4730 | // (X <s C) ? ~C : ~X ==> (~X >s ~C) ? ~C : ~X ==> SMIN(~C, ~X) | |||
4731 | if (match(FalseVal, m_Not(m_Specific(CmpLHS))) && | |||
4732 | match(TrueVal, m_APInt(C2)) && ~(*C1) == *C2) | |||
4733 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false}; | |||
4734 | ||||
4735 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4736 | } | |||
4737 | ||||
4738 | bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW) { | |||
4739 | assert(X && Y && "Invalid operand")((X && Y && "Invalid operand") ? static_cast< void> (0) : __assert_fail ("X && Y && \"Invalid operand\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 4739, __PRETTY_FUNCTION__)); | |||
4740 | ||||
4741 | // X = sub (0, Y) || X = sub nsw (0, Y) | |||
4742 | if ((!NeedNSW && match(X, m_Sub(m_ZeroInt(), m_Specific(Y)))) || | |||
4743 | (NeedNSW && match(X, m_NSWSub(m_ZeroInt(), m_Specific(Y))))) | |||
4744 | return true; | |||
4745 | ||||
4746 | // Y = sub (0, X) || Y = sub nsw (0, X) | |||
4747 | if ((!NeedNSW && match(Y, m_Sub(m_ZeroInt(), m_Specific(X)))) || | |||
4748 | (NeedNSW && match(Y, m_NSWSub(m_ZeroInt(), m_Specific(X))))) | |||
4749 | return true; | |||
4750 | ||||
4751 | // X = sub (A, B), Y = sub (B, A) || X = sub nsw (A, B), Y = sub nsw (B, A) | |||
4752 | Value *A, *B; | |||
4753 | return (!NeedNSW && (match(X, m_Sub(m_Value(A), m_Value(B))) && | |||
4754 | match(Y, m_Sub(m_Specific(B), m_Specific(A))))) || | |||
4755 | (NeedNSW && (match(X, m_NSWSub(m_Value(A), m_Value(B))) && | |||
4756 | match(Y, m_NSWSub(m_Specific(B), m_Specific(A))))); | |||
4757 | } | |||
4758 | ||||
4759 | static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred, | |||
4760 | FastMathFlags FMF, | |||
4761 | Value *CmpLHS, Value *CmpRHS, | |||
4762 | Value *TrueVal, Value *FalseVal, | |||
4763 | Value *&LHS, Value *&RHS, | |||
4764 | unsigned Depth) { | |||
4765 | if (CmpInst::isFPPredicate(Pred)) { | |||
4766 | // IEEE-754 ignores the sign of 0.0 in comparisons. So if the select has one | |||
4767 | // 0.0 operand, set the compare's 0.0 operands to that same value for the | |||
4768 | // purpose of identifying min/max. Disregard vector constants with undefined | |||
4769 | // elements because those can not be back-propagated for analysis. | |||
4770 | Value *OutputZeroVal = nullptr; | |||
4771 | if (match(TrueVal, m_AnyZeroFP()) && !match(FalseVal, m_AnyZeroFP()) && | |||
4772 | !cast<Constant>(TrueVal)->containsUndefElement()) | |||
4773 | OutputZeroVal = TrueVal; | |||
4774 | else if (match(FalseVal, m_AnyZeroFP()) && !match(TrueVal, m_AnyZeroFP()) && | |||
4775 | !cast<Constant>(FalseVal)->containsUndefElement()) | |||
4776 | OutputZeroVal = FalseVal; | |||
4777 | ||||
4778 | if (OutputZeroVal) { | |||
4779 | if (match(CmpLHS, m_AnyZeroFP())) | |||
4780 | CmpLHS = OutputZeroVal; | |||
4781 | if (match(CmpRHS, m_AnyZeroFP())) | |||
4782 | CmpRHS = OutputZeroVal; | |||
4783 | } | |||
4784 | } | |||
4785 | ||||
4786 | LHS = CmpLHS; | |||
4787 | RHS = CmpRHS; | |||
4788 | ||||
4789 | // Signed zero may return inconsistent results between implementations. | |||
4790 | // (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0 | |||
4791 | // minNum(0.0, -0.0) // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1) | |||
4792 | // Therefore, we behave conservatively and only proceed if at least one of the | |||
4793 | // operands is known to not be zero or if we don't care about signed zero. | |||
4794 | switch (Pred) { | |||
4795 | default: break; | |||
4796 | // FIXME: Include OGT/OLT/UGT/ULT. | |||
4797 | case CmpInst::FCMP_OGE: case CmpInst::FCMP_OLE: | |||
4798 | case CmpInst::FCMP_UGE: case CmpInst::FCMP_ULE: | |||
4799 | if (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && | |||
4800 | !isKnownNonZero(CmpRHS)) | |||
4801 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4802 | } | |||
4803 | ||||
4804 | SelectPatternNaNBehavior NaNBehavior = SPNB_NA; | |||
4805 | bool Ordered = false; | |||
4806 | ||||
4807 | // When given one NaN and one non-NaN input: | |||
4808 | // - maxnum/minnum (C99 fmaxf()/fminf()) return the non-NaN input. | |||
4809 | // - A simple C99 (a < b ? a : b) construction will return 'b' (as the | |||
4810 | // ordered comparison fails), which could be NaN or non-NaN. | |||
4811 | // so here we discover exactly what NaN behavior is required/accepted. | |||
4812 | if (CmpInst::isFPPredicate(Pred)) { | |||
4813 | bool LHSSafe = isKnownNonNaN(CmpLHS, FMF); | |||
4814 | bool RHSSafe = isKnownNonNaN(CmpRHS, FMF); | |||
4815 | ||||
4816 | if (LHSSafe && RHSSafe) { | |||
4817 | // Both operands are known non-NaN. | |||
4818 | NaNBehavior = SPNB_RETURNS_ANY; | |||
4819 | } else if (CmpInst::isOrdered(Pred)) { | |||
4820 | // An ordered comparison will return false when given a NaN, so it | |||
4821 | // returns the RHS. | |||
4822 | Ordered = true; | |||
4823 | if (LHSSafe) | |||
4824 | // LHS is non-NaN, so if RHS is NaN then NaN will be returned. | |||
4825 | NaNBehavior = SPNB_RETURNS_NAN; | |||
4826 | else if (RHSSafe) | |||
4827 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
4828 | else | |||
4829 | // Completely unsafe. | |||
4830 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4831 | } else { | |||
4832 | Ordered = false; | |||
4833 | // An unordered comparison will return true when given a NaN, so it | |||
4834 | // returns the LHS. | |||
4835 | if (LHSSafe) | |||
4836 | // LHS is non-NaN, so if RHS is NaN then non-NaN will be returned. | |||
4837 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
4838 | else if (RHSSafe) | |||
4839 | NaNBehavior = SPNB_RETURNS_NAN; | |||
4840 | else | |||
4841 | // Completely unsafe. | |||
4842 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4843 | } | |||
4844 | } | |||
4845 | ||||
4846 | if (TrueVal == CmpRHS && FalseVal == CmpLHS) { | |||
4847 | std::swap(CmpLHS, CmpRHS); | |||
4848 | Pred = CmpInst::getSwappedPredicate(Pred); | |||
4849 | if (NaNBehavior == SPNB_RETURNS_NAN) | |||
4850 | NaNBehavior = SPNB_RETURNS_OTHER; | |||
4851 | else if (NaNBehavior == SPNB_RETURNS_OTHER) | |||
4852 | NaNBehavior = SPNB_RETURNS_NAN; | |||
4853 | Ordered = !Ordered; | |||
4854 | } | |||
4855 | ||||
4856 | // ([if]cmp X, Y) ? X : Y | |||
4857 | if (TrueVal == CmpLHS && FalseVal == CmpRHS) { | |||
4858 | switch (Pred) { | |||
4859 | default: return {SPF_UNKNOWN, SPNB_NA, false}; // Equality. | |||
4860 | case ICmpInst::ICMP_UGT: | |||
4861 | case ICmpInst::ICMP_UGE: return {SPF_UMAX, SPNB_NA, false}; | |||
4862 | case ICmpInst::ICMP_SGT: | |||
4863 | case ICmpInst::ICMP_SGE: return {SPF_SMAX, SPNB_NA, false}; | |||
4864 | case ICmpInst::ICMP_ULT: | |||
4865 | case ICmpInst::ICMP_ULE: return {SPF_UMIN, SPNB_NA, false}; | |||
4866 | case ICmpInst::ICMP_SLT: | |||
4867 | case ICmpInst::ICMP_SLE: return {SPF_SMIN, SPNB_NA, false}; | |||
4868 | case FCmpInst::FCMP_UGT: | |||
4869 | case FCmpInst::FCMP_UGE: | |||
4870 | case FCmpInst::FCMP_OGT: | |||
4871 | case FCmpInst::FCMP_OGE: return {SPF_FMAXNUM, NaNBehavior, Ordered}; | |||
4872 | case FCmpInst::FCMP_ULT: | |||
4873 | case FCmpInst::FCMP_ULE: | |||
4874 | case FCmpInst::FCMP_OLT: | |||
4875 | case FCmpInst::FCMP_OLE: return {SPF_FMINNUM, NaNBehavior, Ordered}; | |||
4876 | } | |||
4877 | } | |||
4878 | ||||
4879 | if (isKnownNegation(TrueVal, FalseVal)) { | |||
4880 | // Sign-extending LHS does not change its sign, so TrueVal/FalseVal can | |||
4881 | // match against either LHS or sext(LHS). | |||
4882 | auto MaybeSExtCmpLHS = | |||
4883 | m_CombineOr(m_Specific(CmpLHS), m_SExt(m_Specific(CmpLHS))); | |||
4884 | auto ZeroOrAllOnes = m_CombineOr(m_ZeroInt(), m_AllOnes()); | |||
4885 | auto ZeroOrOne = m_CombineOr(m_ZeroInt(), m_One()); | |||
4886 | if (match(TrueVal, MaybeSExtCmpLHS)) { | |||
4887 | // Set the return values. If the compare uses the negated value (-X >s 0), | |||
4888 | // swap the return values because the negated value is always 'RHS'. | |||
4889 | LHS = TrueVal; | |||
4890 | RHS = FalseVal; | |||
4891 | if (match(CmpLHS, m_Neg(m_Specific(FalseVal)))) | |||
4892 | std::swap(LHS, RHS); | |||
4893 | ||||
4894 | // (X >s 0) ? X : -X or (X >s -1) ? X : -X --> ABS(X) | |||
4895 | // (-X >s 0) ? -X : X or (-X >s -1) ? -X : X --> ABS(X) | |||
4896 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) | |||
4897 | return {SPF_ABS, SPNB_NA, false}; | |||
4898 | ||||
4899 | // (X >=s 0) ? X : -X or (X >=s 1) ? X : -X --> ABS(X) | |||
4900 | if (Pred == ICmpInst::ICMP_SGE && match(CmpRHS, ZeroOrOne)) | |||
4901 | return {SPF_ABS, SPNB_NA, false}; | |||
4902 | ||||
4903 | // (X <s 0) ? X : -X or (X <s 1) ? X : -X --> NABS(X) | |||
4904 | // (-X <s 0) ? -X : X or (-X <s 1) ? -X : X --> NABS(X) | |||
4905 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) | |||
4906 | return {SPF_NABS, SPNB_NA, false}; | |||
4907 | } | |||
4908 | else if (match(FalseVal, MaybeSExtCmpLHS)) { | |||
4909 | // Set the return values. If the compare uses the negated value (-X >s 0), | |||
4910 | // swap the return values because the negated value is always 'RHS'. | |||
4911 | LHS = FalseVal; | |||
4912 | RHS = TrueVal; | |||
4913 | if (match(CmpLHS, m_Neg(m_Specific(TrueVal)))) | |||
4914 | std::swap(LHS, RHS); | |||
4915 | ||||
4916 | // (X >s 0) ? -X : X or (X >s -1) ? -X : X --> NABS(X) | |||
4917 | // (-X >s 0) ? X : -X or (-X >s -1) ? X : -X --> NABS(X) | |||
4918 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) | |||
4919 | return {SPF_NABS, SPNB_NA, false}; | |||
4920 | ||||
4921 | // (X <s 0) ? -X : X or (X <s 1) ? -X : X --> ABS(X) | |||
4922 | // (-X <s 0) ? X : -X or (-X <s 1) ? X : -X --> ABS(X) | |||
4923 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) | |||
4924 | return {SPF_ABS, SPNB_NA, false}; | |||
4925 | } | |||
4926 | } | |||
4927 | ||||
4928 | if (CmpInst::isIntPredicate(Pred)) | |||
4929 | return matchMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS, Depth); | |||
4930 | ||||
4931 | // According to (IEEE 754-2008 5.3.1), minNum(0.0, -0.0) and similar | |||
4932 | // may return either -0.0 or 0.0, so fcmp/select pair has stricter | |||
4933 | // semantics than minNum. Be conservative in such case. | |||
4934 | if (NaNBehavior != SPNB_RETURNS_ANY || | |||
4935 | (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && | |||
4936 | !isKnownNonZero(CmpRHS))) | |||
4937 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
4938 | ||||
4939 | return matchFastFloatClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS); | |||
4940 | } | |||
4941 | ||||
4942 | /// Helps to match a select pattern in case of a type mismatch. | |||
4943 | /// | |||
4944 | /// The function processes the case when type of true and false values of a | |||
4945 | /// select instruction differs from type of the cmp instruction operands because | |||
4946 | /// of a cast instruction. The function checks if it is legal to move the cast | |||
4947 | /// operation after "select". If yes, it returns the new second value of | |||
4948 | /// "select" (with the assumption that cast is moved): | |||
4949 | /// 1. As operand of cast instruction when both values of "select" are same cast | |||
4950 | /// instructions. | |||
4951 | /// 2. As restored constant (by applying reverse cast operation) when the first | |||
4952 | /// value of the "select" is a cast operation and the second value is a | |||
4953 | /// constant. | |||
4954 | /// NOTE: We return only the new second value because the first value could be | |||
4955 | /// accessed as operand of cast instruction. | |||
4956 | static Value *lookThroughCast(CmpInst *CmpI, Value *V1, Value *V2, | |||
4957 | Instruction::CastOps *CastOp) { | |||
4958 | auto *Cast1 = dyn_cast<CastInst>(V1); | |||
4959 | if (!Cast1) | |||
4960 | return nullptr; | |||
4961 | ||||
4962 | *CastOp = Cast1->getOpcode(); | |||
4963 | Type *SrcTy = Cast1->getSrcTy(); | |||
4964 | if (auto *Cast2 = dyn_cast<CastInst>(V2)) { | |||
4965 | // If V1 and V2 are both the same cast from the same type, look through V1. | |||
4966 | if (*CastOp == Cast2->getOpcode() && SrcTy == Cast2->getSrcTy()) | |||
4967 | return Cast2->getOperand(0); | |||
4968 | return nullptr; | |||
4969 | } | |||
4970 | ||||
4971 | auto *C = dyn_cast<Constant>(V2); | |||
4972 | if (!C) | |||
4973 | return nullptr; | |||
4974 | ||||
4975 | Constant *CastedTo = nullptr; | |||
4976 | switch (*CastOp) { | |||
4977 | case Instruction::ZExt: | |||
4978 | if (CmpI->isUnsigned()) | |||
4979 | CastedTo = ConstantExpr::getTrunc(C, SrcTy); | |||
4980 | break; | |||
4981 | case Instruction::SExt: | |||
4982 | if (CmpI->isSigned()) | |||
4983 | CastedTo = ConstantExpr::getTrunc(C, SrcTy, true); | |||
4984 | break; | |||
4985 | case Instruction::Trunc: | |||
4986 | Constant *CmpConst; | |||
4987 | if (match(CmpI->getOperand(1), m_Constant(CmpConst)) && | |||
4988 | CmpConst->getType() == SrcTy) { | |||
4989 | // Here we have the following case: | |||
4990 | // | |||
4991 | // %cond = cmp iN %x, CmpConst | |||
4992 | // %tr = trunc iN %x to iK | |||
4993 | // %narrowsel = select i1 %cond, iK %t, iK C | |||
4994 | // | |||
4995 | // We can always move trunc after select operation: | |||
4996 | // | |||
4997 | // %cond = cmp iN %x, CmpConst | |||
4998 | // %widesel = select i1 %cond, iN %x, iN CmpConst | |||
4999 | // %tr = trunc iN %widesel to iK | |||
5000 | // | |||
5001 | // Note that C could be extended in any way because we don't care about | |||
5002 | // upper bits after truncation. It can't be abs pattern, because it would | |||
5003 | // look like: | |||
5004 | // | |||
5005 | // select i1 %cond, x, -x. | |||
5006 | // | |||
5007 | // So only min/max pattern could be matched. Such match requires widened C | |||
5008 | // == CmpConst. That is why set widened C = CmpConst, condition trunc | |||
5009 | // CmpConst == C is checked below. | |||
5010 | CastedTo = CmpConst; | |||
5011 | } else { | |||
5012 | CastedTo = ConstantExpr::getIntegerCast(C, SrcTy, CmpI->isSigned()); | |||
5013 | } | |||
5014 | break; | |||
5015 | case Instruction::FPTrunc: | |||
5016 | CastedTo = ConstantExpr::getFPExtend(C, SrcTy, true); | |||
5017 | break; | |||
5018 | case Instruction::FPExt: | |||
5019 | CastedTo = ConstantExpr::getFPTrunc(C, SrcTy, true); | |||
5020 | break; | |||
5021 | case Instruction::FPToUI: | |||
5022 | CastedTo = ConstantExpr::getUIToFP(C, SrcTy, true); | |||
5023 | break; | |||
5024 | case Instruction::FPToSI: | |||
5025 | CastedTo = ConstantExpr::getSIToFP(C, SrcTy, true); | |||
5026 | break; | |||
5027 | case Instruction::UIToFP: | |||
5028 | CastedTo = ConstantExpr::getFPToUI(C, SrcTy, true); | |||
5029 | break; | |||
5030 | case Instruction::SIToFP: | |||
5031 | CastedTo = ConstantExpr::getFPToSI(C, SrcTy, true); | |||
5032 | break; | |||
5033 | default: | |||
5034 | break; | |||
5035 | } | |||
5036 | ||||
5037 | if (!CastedTo) | |||
5038 | return nullptr; | |||
5039 | ||||
5040 | // Make sure the cast doesn't lose any information. | |||
5041 | Constant *CastedBack = | |||
5042 | ConstantExpr::getCast(*CastOp, CastedTo, C->getType(), true); | |||
5043 | if (CastedBack != C) | |||
5044 | return nullptr; | |||
5045 | ||||
5046 | return CastedTo; | |||
5047 | } | |||
5048 | ||||
5049 | SelectPatternResult llvm::matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, | |||
5050 | Instruction::CastOps *CastOp, | |||
5051 | unsigned Depth) { | |||
5052 | if (Depth >= MaxDepth) | |||
5053 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5054 | ||||
5055 | SelectInst *SI = dyn_cast<SelectInst>(V); | |||
5056 | if (!SI) return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5057 | ||||
5058 | CmpInst *CmpI = dyn_cast<CmpInst>(SI->getCondition()); | |||
5059 | if (!CmpI) return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5060 | ||||
5061 | Value *TrueVal = SI->getTrueValue(); | |||
5062 | Value *FalseVal = SI->getFalseValue(); | |||
5063 | ||||
5064 | return llvm::matchDecomposedSelectPattern(CmpI, TrueVal, FalseVal, LHS, RHS, | |||
5065 | CastOp, Depth); | |||
5066 | } | |||
5067 | ||||
5068 | SelectPatternResult llvm::matchDecomposedSelectPattern( | |||
5069 | CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS, | |||
5070 | Instruction::CastOps *CastOp, unsigned Depth) { | |||
5071 | CmpInst::Predicate Pred = CmpI->getPredicate(); | |||
5072 | Value *CmpLHS = CmpI->getOperand(0); | |||
5073 | Value *CmpRHS = CmpI->getOperand(1); | |||
5074 | FastMathFlags FMF; | |||
5075 | if (isa<FPMathOperator>(CmpI)) | |||
5076 | FMF = CmpI->getFastMathFlags(); | |||
5077 | ||||
5078 | // Bail out early. | |||
5079 | if (CmpI->isEquality()) | |||
5080 | return {SPF_UNKNOWN, SPNB_NA, false}; | |||
5081 | ||||
5082 | // Deal with type mismatches. | |||
5083 | if (CastOp && CmpLHS->getType() != TrueVal->getType()) { | |||
5084 | if (Value *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp)) { | |||
5085 | // If this is a potential fmin/fmax with a cast to integer, then ignore | |||
5086 | // -0.0 because there is no corresponding integer value. | |||
5087 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) | |||
5088 | FMF.setNoSignedZeros(); | |||
5089 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, | |||
5090 | cast<CastInst>(TrueVal)->getOperand(0), C, | |||
5091 | LHS, RHS, Depth); | |||
5092 | } | |||
5093 | if (Value *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp)) { | |||
5094 | // If this is a potential fmin/fmax with a cast to integer, then ignore | |||
5095 | // -0.0 because there is no corresponding integer value. | |||
5096 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) | |||
5097 | FMF.setNoSignedZeros(); | |||
5098 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, | |||
5099 | C, cast<CastInst>(FalseVal)->getOperand(0), | |||
5100 | LHS, RHS, Depth); | |||
5101 | } | |||
5102 | } | |||
5103 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, TrueVal, FalseVal, | |||
5104 | LHS, RHS, Depth); | |||
5105 | } | |||
5106 | ||||
5107 | CmpInst::Predicate llvm::getMinMaxPred(SelectPatternFlavor SPF, bool Ordered) { | |||
5108 | if (SPF == SPF_SMIN) return ICmpInst::ICMP_SLT; | |||
5109 | if (SPF == SPF_UMIN) return ICmpInst::ICMP_ULT; | |||
5110 | if (SPF == SPF_SMAX) return ICmpInst::ICMP_SGT; | |||
5111 | if (SPF == SPF_UMAX) return ICmpInst::ICMP_UGT; | |||
5112 | if (SPF == SPF_FMINNUM) | |||
5113 | return Ordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; | |||
5114 | if (SPF == SPF_FMAXNUM) | |||
5115 | return Ordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; | |||
5116 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5116); | |||
5117 | } | |||
5118 | ||||
5119 | SelectPatternFlavor llvm::getInverseMinMaxFlavor(SelectPatternFlavor SPF) { | |||
5120 | if (SPF == SPF_SMIN) return SPF_SMAX; | |||
5121 | if (SPF == SPF_UMIN) return SPF_UMAX; | |||
5122 | if (SPF == SPF_SMAX) return SPF_SMIN; | |||
5123 | if (SPF == SPF_UMAX) return SPF_UMIN; | |||
5124 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5124); | |||
5125 | } | |||
5126 | ||||
5127 | CmpInst::Predicate llvm::getInverseMinMaxPred(SelectPatternFlavor SPF) { | |||
5128 | return getMinMaxPred(getInverseMinMaxFlavor(SPF)); | |||
5129 | } | |||
5130 | ||||
5131 | /// Return true if "icmp Pred LHS RHS" is always true. | |||
5132 | static bool isTruePredicate(CmpInst::Predicate Pred, const Value *LHS, | |||
5133 | const Value *RHS, const DataLayout &DL, | |||
5134 | unsigned Depth) { | |||
5135 | assert(!LHS->getType()->isVectorTy() && "TODO: extend to handle vectors!")((!LHS->getType()->isVectorTy() && "TODO: extend to handle vectors!" ) ? static_cast<void> (0) : __assert_fail ("!LHS->getType()->isVectorTy() && \"TODO: extend to handle vectors!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5135, __PRETTY_FUNCTION__)); | |||
5136 | if (ICmpInst::isTrueWhenEqual(Pred) && LHS == RHS) | |||
5137 | return true; | |||
5138 | ||||
5139 | switch (Pred) { | |||
5140 | default: | |||
5141 | return false; | |||
5142 | ||||
5143 | case CmpInst::ICMP_SLE: { | |||
5144 | const APInt *C; | |||
5145 | ||||
5146 | // LHS s<= LHS +_{nsw} C if C >= 0 | |||
5147 | if (match(RHS, m_NSWAdd(m_Specific(LHS), m_APInt(C)))) | |||
5148 | return !C->isNegative(); | |||
5149 | return false; | |||
5150 | } | |||
5151 | ||||
5152 | case CmpInst::ICMP_ULE: { | |||
5153 | const APInt *C; | |||
5154 | ||||
5155 | // LHS u<= LHS +_{nuw} C for any C | |||
5156 | if (match(RHS, m_NUWAdd(m_Specific(LHS), m_APInt(C)))) | |||
5157 | return true; | |||
5158 | ||||
5159 | // Match A to (X +_{nuw} CA) and B to (X +_{nuw} CB) | |||
5160 | auto MatchNUWAddsToSameValue = [&](const Value *A, const Value *B, | |||
5161 | const Value *&X, | |||
5162 | const APInt *&CA, const APInt *&CB) { | |||
5163 | if (match(A, m_NUWAdd(m_Value(X), m_APInt(CA))) && | |||
5164 | match(B, m_NUWAdd(m_Specific(X), m_APInt(CB)))) | |||
5165 | return true; | |||
5166 | ||||
5167 | // If X & C == 0 then (X | C) == X +_{nuw} C | |||
5168 | if (match(A, m_Or(m_Value(X), m_APInt(CA))) && | |||
5169 | match(B, m_Or(m_Specific(X), m_APInt(CB)))) { | |||
5170 | KnownBits Known(CA->getBitWidth()); | |||
5171 | computeKnownBits(X, Known, DL, Depth + 1, /*AC*/ nullptr, | |||
5172 | /*CxtI*/ nullptr, /*DT*/ nullptr); | |||
5173 | if (CA->isSubsetOf(Known.Zero) && CB->isSubsetOf(Known.Zero)) | |||
5174 | return true; | |||
5175 | } | |||
5176 | ||||
5177 | return false; | |||
5178 | }; | |||
5179 | ||||
5180 | const Value *X; | |||
5181 | const APInt *CLHS, *CRHS; | |||
5182 | if (MatchNUWAddsToSameValue(LHS, RHS, X, CLHS, CRHS)) | |||
5183 | return CLHS->ule(*CRHS); | |||
5184 | ||||
5185 | return false; | |||
5186 | } | |||
5187 | } | |||
5188 | } | |||
5189 | ||||
5190 | /// Return true if "icmp Pred BLHS BRHS" is true whenever "icmp Pred | |||
5191 | /// ALHS ARHS" is true. Otherwise, return None. | |||
5192 | static Optional<bool> | |||
5193 | isImpliedCondOperands(CmpInst::Predicate Pred, const Value *ALHS, | |||
5194 | const Value *ARHS, const Value *BLHS, const Value *BRHS, | |||
5195 | const DataLayout &DL, unsigned Depth) { | |||
5196 | switch (Pred) { | |||
5197 | default: | |||
5198 | return None; | |||
5199 | ||||
5200 | case CmpInst::ICMP_SLT: | |||
5201 | case CmpInst::ICMP_SLE: | |||
5202 | if (isTruePredicate(CmpInst::ICMP_SLE, BLHS, ALHS, DL, Depth) && | |||
5203 | isTruePredicate(CmpInst::ICMP_SLE, ARHS, BRHS, DL, Depth)) | |||
5204 | return true; | |||
5205 | return None; | |||
5206 | ||||
5207 | case CmpInst::ICMP_ULT: | |||
5208 | case CmpInst::ICMP_ULE: | |||
5209 | if (isTruePredicate(CmpInst::ICMP_ULE, BLHS, ALHS, DL, Depth) && | |||
5210 | isTruePredicate(CmpInst::ICMP_ULE, ARHS, BRHS, DL, Depth)) | |||
5211 | return true; | |||
5212 | return None; | |||
5213 | } | |||
5214 | } | |||
5215 | ||||
5216 | /// Return true if the operands of the two compares match. IsSwappedOps is true | |||
5217 | /// when the operands match, but are swapped. | |||
5218 | static bool isMatchingOps(const Value *ALHS, const Value *ARHS, | |||
5219 | const Value *BLHS, const Value *BRHS, | |||
5220 | bool &IsSwappedOps) { | |||
5221 | ||||
5222 | bool IsMatchingOps = (ALHS == BLHS && ARHS == BRHS); | |||
5223 | IsSwappedOps = (ALHS == BRHS && ARHS == BLHS); | |||
5224 | return IsMatchingOps || IsSwappedOps; | |||
5225 | } | |||
5226 | ||||
5227 | /// Return true if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is true. | |||
5228 | /// Return false if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is false. | |||
5229 | /// Otherwise, return None if we can't infer anything. | |||
5230 | static Optional<bool> isImpliedCondMatchingOperands(CmpInst::Predicate APred, | |||
5231 | CmpInst::Predicate BPred, | |||
5232 | bool AreSwappedOps) { | |||
5233 | // Canonicalize the predicate as if the operands were not commuted. | |||
5234 | if (AreSwappedOps) | |||
5235 | BPred = ICmpInst::getSwappedPredicate(BPred); | |||
5236 | ||||
5237 | if (CmpInst::isImpliedTrueByMatchingCmp(APred, BPred)) | |||
5238 | return true; | |||
5239 | if (CmpInst::isImpliedFalseByMatchingCmp(APred, BPred)) | |||
5240 | return false; | |||
5241 | ||||
5242 | return None; | |||
5243 | } | |||
5244 | ||||
5245 | /// Return true if "icmp APred X, C1" implies "icmp BPred X, C2" is true. | |||
5246 | /// Return false if "icmp APred X, C1" implies "icmp BPred X, C2" is false. | |||
5247 | /// Otherwise, return None if we can't infer anything. | |||
5248 | static Optional<bool> | |||
5249 | isImpliedCondMatchingImmOperands(CmpInst::Predicate APred, | |||
5250 | const ConstantInt *C1, | |||
5251 | CmpInst::Predicate BPred, | |||
5252 | const ConstantInt *C2) { | |||
5253 | ConstantRange DomCR = | |||
5254 | ConstantRange::makeExactICmpRegion(APred, C1->getValue()); | |||
5255 | ConstantRange CR = | |||
5256 | ConstantRange::makeAllowedICmpRegion(BPred, C2->getValue()); | |||
5257 | ConstantRange Intersection = DomCR.intersectWith(CR); | |||
5258 | ConstantRange Difference = DomCR.difference(CR); | |||
5259 | if (Intersection.isEmptySet()) | |||
5260 | return false; | |||
5261 | if (Difference.isEmptySet()) | |||
5262 | return true; | |||
5263 | return None; | |||
5264 | } | |||
5265 | ||||
5266 | /// Return true if LHS implies RHS is true. Return false if LHS implies RHS is | |||
5267 | /// false. Otherwise, return None if we can't infer anything. | |||
5268 | static Optional<bool> isImpliedCondICmps(const ICmpInst *LHS, | |||
5269 | const ICmpInst *RHS, | |||
5270 | const DataLayout &DL, bool LHSIsTrue, | |||
5271 | unsigned Depth) { | |||
5272 | Value *ALHS = LHS->getOperand(0); | |||
5273 | Value *ARHS = LHS->getOperand(1); | |||
5274 | // The rest of the logic assumes the LHS condition is true. If that's not the | |||
5275 | // case, invert the predicate to make it so. | |||
5276 | ICmpInst::Predicate APred = | |||
5277 | LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate(); | |||
5278 | ||||
5279 | Value *BLHS = RHS->getOperand(0); | |||
5280 | Value *BRHS = RHS->getOperand(1); | |||
5281 | ICmpInst::Predicate BPred = RHS->getPredicate(); | |||
5282 | ||||
5283 | // Can we infer anything when the two compares have matching operands? | |||
5284 | bool AreSwappedOps; | |||
5285 | if (isMatchingOps(ALHS, ARHS, BLHS, BRHS, AreSwappedOps)) { | |||
5286 | if (Optional<bool> Implication = isImpliedCondMatchingOperands( | |||
5287 | APred, BPred, AreSwappedOps)) | |||
5288 | return Implication; | |||
5289 | // No amount of additional analysis will infer the second condition, so | |||
5290 | // early exit. | |||
5291 | return None; | |||
5292 | } | |||
5293 | ||||
5294 | // Can we infer anything when the LHS operands match and the RHS operands are | |||
5295 | // constants (not necessarily matching)? | |||
5296 | if (ALHS == BLHS && isa<ConstantInt>(ARHS) && isa<ConstantInt>(BRHS)) { | |||
5297 | if (Optional<bool> Implication = isImpliedCondMatchingImmOperands( | |||
5298 | APred, cast<ConstantInt>(ARHS), BPred, cast<ConstantInt>(BRHS))) | |||
5299 | return Implication; | |||
5300 | // No amount of additional analysis will infer the second condition, so | |||
5301 | // early exit. | |||
5302 | return None; | |||
5303 | } | |||
5304 | ||||
5305 | if (APred == BPred) | |||
5306 | return isImpliedCondOperands(APred, ALHS, ARHS, BLHS, BRHS, DL, Depth); | |||
5307 | return None; | |||
5308 | } | |||
5309 | ||||
5310 | /// Return true if LHS implies RHS is true. Return false if LHS implies RHS is | |||
5311 | /// false. Otherwise, return None if we can't infer anything. We expect the | |||
5312 | /// RHS to be an icmp and the LHS to be an 'and' or an 'or' instruction. | |||
5313 | static Optional<bool> isImpliedCondAndOr(const BinaryOperator *LHS, | |||
5314 | const ICmpInst *RHS, | |||
5315 | const DataLayout &DL, bool LHSIsTrue, | |||
5316 | unsigned Depth) { | |||
5317 | // The LHS must be an 'or' or an 'and' instruction. | |||
5318 | assert((LHS->getOpcode() == Instruction::And ||(((LHS->getOpcode() == Instruction::And || LHS->getOpcode () == Instruction::Or) && "Expected LHS to be 'and' or 'or'." ) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or) && \"Expected LHS to be 'and' or 'or'.\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5320, __PRETTY_FUNCTION__)) | |||
5319 | LHS->getOpcode() == Instruction::Or) &&(((LHS->getOpcode() == Instruction::And || LHS->getOpcode () == Instruction::Or) && "Expected LHS to be 'and' or 'or'." ) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or) && \"Expected LHS to be 'and' or 'or'.\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5320, __PRETTY_FUNCTION__)) | |||
5320 | "Expected LHS to be 'and' or 'or'.")(((LHS->getOpcode() == Instruction::And || LHS->getOpcode () == Instruction::Or) && "Expected LHS to be 'and' or 'or'." ) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or) && \"Expected LHS to be 'and' or 'or'.\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5320, __PRETTY_FUNCTION__)); | |||
5321 | ||||
5322 | assert(Depth <= MaxDepth && "Hit recursion limit")((Depth <= MaxDepth && "Hit recursion limit") ? static_cast <void> (0) : __assert_fail ("Depth <= MaxDepth && \"Hit recursion limit\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5322, __PRETTY_FUNCTION__)); | |||
5323 | ||||
5324 | // If the result of an 'or' is false, then we know both legs of the 'or' are | |||
5325 | // false. Similarly, if the result of an 'and' is true, then we know both | |||
5326 | // legs of the 'and' are true. | |||
5327 | Value *ALHS, *ARHS; | |||
5328 | if ((!LHSIsTrue && match(LHS, m_Or(m_Value(ALHS), m_Value(ARHS)))) || | |||
5329 | (LHSIsTrue && match(LHS, m_And(m_Value(ALHS), m_Value(ARHS))))) { | |||
5330 | // FIXME: Make this non-recursion. | |||
5331 | if (Optional<bool> Implication = | |||
5332 | isImpliedCondition(ALHS, RHS, DL, LHSIsTrue, Depth + 1)) | |||
5333 | return Implication; | |||
5334 | if (Optional<bool> Implication = | |||
5335 | isImpliedCondition(ARHS, RHS, DL, LHSIsTrue, Depth + 1)) | |||
5336 | return Implication; | |||
5337 | return None; | |||
5338 | } | |||
5339 | return None; | |||
5340 | } | |||
5341 | ||||
5342 | Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS, | |||
5343 | const DataLayout &DL, bool LHSIsTrue, | |||
5344 | unsigned Depth) { | |||
5345 | // Bail out when we hit the limit. | |||
5346 | if (Depth == MaxDepth) | |||
5347 | return None; | |||
5348 | ||||
5349 | // A mismatch occurs when we compare a scalar cmp to a vector cmp, for | |||
5350 | // example. | |||
5351 | if (LHS->getType() != RHS->getType()) | |||
5352 | return None; | |||
5353 | ||||
5354 | Type *OpTy = LHS->getType(); | |||
5355 | assert(OpTy->isIntOrIntVectorTy(1) && "Expected integer type only!")((OpTy->isIntOrIntVectorTy(1) && "Expected integer type only!" ) ? static_cast<void> (0) : __assert_fail ("OpTy->isIntOrIntVectorTy(1) && \"Expected integer type only!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5355, __PRETTY_FUNCTION__)); | |||
5356 | ||||
5357 | // LHS ==> RHS by definition | |||
5358 | if (LHS == RHS) | |||
5359 | return LHSIsTrue; | |||
5360 | ||||
5361 | // FIXME: Extending the code below to handle vectors. | |||
5362 | if (OpTy->isVectorTy()) | |||
5363 | return None; | |||
5364 | ||||
5365 | assert(OpTy->isIntegerTy(1) && "implied by above")((OpTy->isIntegerTy(1) && "implied by above") ? static_cast <void> (0) : __assert_fail ("OpTy->isIntegerTy(1) && \"implied by above\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5365, __PRETTY_FUNCTION__)); | |||
5366 | ||||
5367 | // Both LHS and RHS are icmps. | |||
5368 | const ICmpInst *LHSCmp = dyn_cast<ICmpInst>(LHS); | |||
5369 | const ICmpInst *RHSCmp = dyn_cast<ICmpInst>(RHS); | |||
5370 | if (LHSCmp && RHSCmp) | |||
5371 | return isImpliedCondICmps(LHSCmp, RHSCmp, DL, LHSIsTrue, Depth); | |||
5372 | ||||
5373 | // The LHS should be an 'or' or an 'and' instruction. We expect the RHS to be | |||
5374 | // an icmp. FIXME: Add support for and/or on the RHS. | |||
5375 | const BinaryOperator *LHSBO = dyn_cast<BinaryOperator>(LHS); | |||
5376 | if (LHSBO && RHSCmp) { | |||
5377 | if ((LHSBO->getOpcode() == Instruction::And || | |||
5378 | LHSBO->getOpcode() == Instruction::Or)) | |||
5379 | return isImpliedCondAndOr(LHSBO, RHSCmp, DL, LHSIsTrue, Depth); | |||
5380 | } | |||
5381 | return None; | |||
5382 | } | |||
5383 | ||||
5384 | Optional<bool> llvm::isImpliedByDomCondition(const Value *Cond, | |||
5385 | const Instruction *ContextI, | |||
5386 | const DataLayout &DL) { | |||
5387 | assert(Cond->getType()->isIntOrIntVectorTy(1) && "Condition must be bool")((Cond->getType()->isIntOrIntVectorTy(1) && "Condition must be bool" ) ? static_cast<void> (0) : __assert_fail ("Cond->getType()->isIntOrIntVectorTy(1) && \"Condition must be bool\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5387, __PRETTY_FUNCTION__)); | |||
5388 | if (!ContextI || !ContextI->getParent()) | |||
5389 | return None; | |||
5390 | ||||
5391 | // TODO: This is a poor/cheap way to determine dominance. Should we use a | |||
5392 | // dominator tree (eg, from a SimplifyQuery) instead? | |||
5393 | const BasicBlock *ContextBB = ContextI->getParent(); | |||
5394 | const BasicBlock *PredBB = ContextBB->getSinglePredecessor(); | |||
5395 | if (!PredBB) | |||
5396 | return None; | |||
5397 | ||||
5398 | // We need a conditional branch in the predecessor. | |||
5399 | Value *PredCond; | |||
5400 | BasicBlock *TrueBB, *FalseBB; | |||
5401 | if (!match(PredBB->getTerminator(), m_Br(m_Value(PredCond), TrueBB, FalseBB))) | |||
5402 | return None; | |||
5403 | ||||
5404 | // The branch should get simplified. Don't bother simplifying this condition. | |||
5405 | if (TrueBB == FalseBB) | |||
5406 | return None; | |||
5407 | ||||
5408 | assert((TrueBB == ContextBB || FalseBB == ContextBB) &&(((TrueBB == ContextBB || FalseBB == ContextBB) && "Predecessor block does not point to successor?" ) ? static_cast<void> (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5409, __PRETTY_FUNCTION__)) | |||
5409 | "Predecessor block does not point to successor?")(((TrueBB == ContextBB || FalseBB == ContextBB) && "Predecessor block does not point to successor?" ) ? static_cast<void> (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5409, __PRETTY_FUNCTION__)); | |||
5410 | ||||
5411 | // Is this condition implied by the predecessor condition? | |||
5412 | bool CondIsTrue = TrueBB == ContextBB; | |||
5413 | return isImpliedCondition(PredCond, Cond, DL, CondIsTrue); | |||
5414 | } | |||
5415 | ||||
5416 | static void setLimitsForBinOp(const BinaryOperator &BO, APInt &Lower, | |||
5417 | APInt &Upper, const InstrInfoQuery &IIQ) { | |||
5418 | unsigned Width = Lower.getBitWidth(); | |||
5419 | const APInt *C; | |||
5420 | switch (BO.getOpcode()) { | |||
5421 | case Instruction::Add: | |||
5422 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) { | |||
5423 | // FIXME: If we have both nuw and nsw, we should reduce the range further. | |||
5424 | if (IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(&BO))) { | |||
5425 | // 'add nuw x, C' produces [C, UINT_MAX]. | |||
5426 | Lower = *C; | |||
5427 | } else if (IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(&BO))) { | |||
5428 | if (C->isNegative()) { | |||
5429 | // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C]. | |||
5430 | Lower = APInt::getSignedMinValue(Width); | |||
5431 | Upper = APInt::getSignedMaxValue(Width) + *C + 1; | |||
5432 | } else { | |||
5433 | // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX]. | |||
5434 | Lower = APInt::getSignedMinValue(Width) + *C; | |||
5435 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
5436 | } | |||
5437 | } | |||
5438 | } | |||
5439 | break; | |||
5440 | ||||
5441 | case Instruction::And: | |||
5442 | if (match(BO.getOperand(1), m_APInt(C))) | |||
5443 | // 'and x, C' produces [0, C]. | |||
5444 | Upper = *C + 1; | |||
5445 | break; | |||
5446 | ||||
5447 | case Instruction::Or: | |||
5448 | if (match(BO.getOperand(1), m_APInt(C))) | |||
5449 | // 'or x, C' produces [C, UINT_MAX]. | |||
5450 | Lower = *C; | |||
5451 | break; | |||
5452 | ||||
5453 | case Instruction::AShr: | |||
5454 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { | |||
5455 | // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C]. | |||
5456 | Lower = APInt::getSignedMinValue(Width).ashr(*C); | |||
5457 | Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1; | |||
5458 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
5459 | unsigned ShiftAmount = Width - 1; | |||
5460 | if (!C->isNullValue() && IIQ.isExact(&BO)) | |||
5461 | ShiftAmount = C->countTrailingZeros(); | |||
5462 | if (C->isNegative()) { | |||
5463 | // 'ashr C, x' produces [C, C >> (Width-1)] | |||
5464 | Lower = *C; | |||
5465 | Upper = C->ashr(ShiftAmount) + 1; | |||
5466 | } else { | |||
5467 | // 'ashr C, x' produces [C >> (Width-1), C] | |||
5468 | Lower = C->ashr(ShiftAmount); | |||
5469 | Upper = *C + 1; | |||
5470 | } | |||
5471 | } | |||
5472 | break; | |||
5473 | ||||
5474 | case Instruction::LShr: | |||
5475 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { | |||
5476 | // 'lshr x, C' produces [0, UINT_MAX >> C]. | |||
5477 | Upper = APInt::getAllOnesValue(Width).lshr(*C) + 1; | |||
5478 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
5479 | // 'lshr C, x' produces [C >> (Width-1), C]. | |||
5480 | unsigned ShiftAmount = Width - 1; | |||
5481 | if (!C->isNullValue() && IIQ.isExact(&BO)) | |||
5482 | ShiftAmount = C->countTrailingZeros(); | |||
5483 | Lower = C->lshr(ShiftAmount); | |||
5484 | Upper = *C + 1; | |||
5485 | } | |||
5486 | break; | |||
5487 | ||||
5488 | case Instruction::Shl: | |||
5489 | if (match(BO.getOperand(0), m_APInt(C))) { | |||
5490 | if (IIQ.hasNoUnsignedWrap(&BO)) { | |||
5491 | // 'shl nuw C, x' produces [C, C << CLZ(C)] | |||
5492 | Lower = *C; | |||
5493 | Upper = Lower.shl(Lower.countLeadingZeros()) + 1; | |||
5494 | } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw? | |||
5495 | if (C->isNegative()) { | |||
5496 | // 'shl nsw C, x' produces [C << CLO(C)-1, C] | |||
5497 | unsigned ShiftAmount = C->countLeadingOnes() - 1; | |||
5498 | Lower = C->shl(ShiftAmount); | |||
5499 | Upper = *C + 1; | |||
5500 | } else { | |||
5501 | // 'shl nsw C, x' produces [C, C << CLZ(C)-1] | |||
5502 | unsigned ShiftAmount = C->countLeadingZeros() - 1; | |||
5503 | Lower = *C; | |||
5504 | Upper = C->shl(ShiftAmount) + 1; | |||
5505 | } | |||
5506 | } | |||
5507 | } | |||
5508 | break; | |||
5509 | ||||
5510 | case Instruction::SDiv: | |||
5511 | if (match(BO.getOperand(1), m_APInt(C))) { | |||
5512 | APInt IntMin = APInt::getSignedMinValue(Width); | |||
5513 | APInt IntMax = APInt::getSignedMaxValue(Width); | |||
5514 | if (C->isAllOnesValue()) { | |||
5515 | // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX] | |||
5516 | // where C != -1 and C != 0 and C != 1 | |||
5517 | Lower = IntMin + 1; | |||
5518 | Upper = IntMax + 1; | |||
5519 | } else if (C->countLeadingZeros() < Width - 1) { | |||
5520 | // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C] | |||
5521 | // where C != -1 and C != 0 and C != 1 | |||
5522 | Lower = IntMin.sdiv(*C); | |||
5523 | Upper = IntMax.sdiv(*C); | |||
5524 | if (Lower.sgt(Upper)) | |||
5525 | std::swap(Lower, Upper); | |||
5526 | Upper = Upper + 1; | |||
5527 | assert(Upper != Lower && "Upper part of range has wrapped!")((Upper != Lower && "Upper part of range has wrapped!" ) ? static_cast<void> (0) : __assert_fail ("Upper != Lower && \"Upper part of range has wrapped!\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5527, __PRETTY_FUNCTION__)); | |||
5528 | } | |||
5529 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
5530 | if (C->isMinSignedValue()) { | |||
5531 | // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2]. | |||
5532 | Lower = *C; | |||
5533 | Upper = Lower.lshr(1) + 1; | |||
5534 | } else { | |||
5535 | // 'sdiv C, x' produces [-|C|, |C|]. | |||
5536 | Upper = C->abs() + 1; | |||
5537 | Lower = (-Upper) + 1; | |||
5538 | } | |||
5539 | } | |||
5540 | break; | |||
5541 | ||||
5542 | case Instruction::UDiv: | |||
5543 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) { | |||
5544 | // 'udiv x, C' produces [0, UINT_MAX / C]. | |||
5545 | Upper = APInt::getMaxValue(Width).udiv(*C) + 1; | |||
5546 | } else if (match(BO.getOperand(0), m_APInt(C))) { | |||
5547 | // 'udiv C, x' produces [0, C]. | |||
5548 | Upper = *C + 1; | |||
5549 | } | |||
5550 | break; | |||
5551 | ||||
5552 | case Instruction::SRem: | |||
5553 | if (match(BO.getOperand(1), m_APInt(C))) { | |||
5554 | // 'srem x, C' produces (-|C|, |C|). | |||
5555 | Upper = C->abs(); | |||
5556 | Lower = (-Upper) + 1; | |||
5557 | } | |||
5558 | break; | |||
5559 | ||||
5560 | case Instruction::URem: | |||
5561 | if (match(BO.getOperand(1), m_APInt(C))) | |||
5562 | // 'urem x, C' produces [0, C). | |||
5563 | Upper = *C; | |||
5564 | break; | |||
5565 | ||||
5566 | default: | |||
5567 | break; | |||
5568 | } | |||
5569 | } | |||
5570 | ||||
5571 | static void setLimitsForIntrinsic(const IntrinsicInst &II, APInt &Lower, | |||
5572 | APInt &Upper) { | |||
5573 | unsigned Width = Lower.getBitWidth(); | |||
5574 | const APInt *C; | |||
5575 | switch (II.getIntrinsicID()) { | |||
5576 | case Intrinsic::uadd_sat: | |||
5577 | // uadd.sat(x, C) produces [C, UINT_MAX]. | |||
5578 | if (match(II.getOperand(0), m_APInt(C)) || | |||
5579 | match(II.getOperand(1), m_APInt(C))) | |||
5580 | Lower = *C; | |||
5581 | break; | |||
5582 | case Intrinsic::sadd_sat: | |||
5583 | if (match(II.getOperand(0), m_APInt(C)) || | |||
5584 | match(II.getOperand(1), m_APInt(C))) { | |||
5585 | if (C->isNegative()) { | |||
5586 | // sadd.sat(x, -C) produces [SINT_MIN, SINT_MAX + (-C)]. | |||
5587 | Lower = APInt::getSignedMinValue(Width); | |||
5588 | Upper = APInt::getSignedMaxValue(Width) + *C + 1; | |||
5589 | } else { | |||
5590 | // sadd.sat(x, +C) produces [SINT_MIN + C, SINT_MAX]. | |||
5591 | Lower = APInt::getSignedMinValue(Width) + *C; | |||
5592 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
5593 | } | |||
5594 | } | |||
5595 | break; | |||
5596 | case Intrinsic::usub_sat: | |||
5597 | // usub.sat(C, x) produces [0, C]. | |||
5598 | if (match(II.getOperand(0), m_APInt(C))) | |||
5599 | Upper = *C + 1; | |||
5600 | // usub.sat(x, C) produces [0, UINT_MAX - C]. | |||
5601 | else if (match(II.getOperand(1), m_APInt(C))) | |||
5602 | Upper = APInt::getMaxValue(Width) - *C + 1; | |||
5603 | break; | |||
5604 | case Intrinsic::ssub_sat: | |||
5605 | if (match(II.getOperand(0), m_APInt(C))) { | |||
5606 | if (C->isNegative()) { | |||
5607 | // ssub.sat(-C, x) produces [SINT_MIN, -SINT_MIN + (-C)]. | |||
5608 | Lower = APInt::getSignedMinValue(Width); | |||
5609 | Upper = *C - APInt::getSignedMinValue(Width) + 1; | |||
5610 | } else { | |||
5611 | // ssub.sat(+C, x) produces [-SINT_MAX + C, SINT_MAX]. | |||
5612 | Lower = *C - APInt::getSignedMaxValue(Width); | |||
5613 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
5614 | } | |||
5615 | } else if (match(II.getOperand(1), m_APInt(C))) { | |||
5616 | if (C->isNegative()) { | |||
5617 | // ssub.sat(x, -C) produces [SINT_MIN - (-C), SINT_MAX]: | |||
5618 | Lower = APInt::getSignedMinValue(Width) - *C; | |||
5619 | Upper = APInt::getSignedMaxValue(Width) + 1; | |||
5620 | } else { | |||
5621 | // ssub.sat(x, +C) produces [SINT_MIN, SINT_MAX - C]. | |||
5622 | Lower = APInt::getSignedMinValue(Width); | |||
5623 | Upper = APInt::getSignedMaxValue(Width) - *C + 1; | |||
5624 | } | |||
5625 | } | |||
5626 | break; | |||
5627 | default: | |||
5628 | break; | |||
5629 | } | |||
5630 | } | |||
5631 | ||||
5632 | static void setLimitsForSelectPattern(const SelectInst &SI, APInt &Lower, | |||
5633 | APInt &Upper, const InstrInfoQuery &IIQ) { | |||
5634 | const Value *LHS, *RHS; | |||
5635 | SelectPatternResult R = matchSelectPattern(&SI, LHS, RHS); | |||
5636 | if (R.Flavor == SPF_UNKNOWN) | |||
5637 | return; | |||
5638 | ||||
5639 | unsigned BitWidth = SI.getType()->getScalarSizeInBits(); | |||
5640 | ||||
5641 | if (R.Flavor == SelectPatternFlavor::SPF_ABS) { | |||
5642 | // If the negation part of the abs (in RHS) has the NSW flag, | |||
5643 | // then the result of abs(X) is [0..SIGNED_MAX], | |||
5644 | // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN. | |||
5645 | Lower = APInt::getNullValue(BitWidth); | |||
5646 | if (match(RHS, m_Neg(m_Specific(LHS))) && | |||
5647 | IIQ.hasNoSignedWrap(cast<Instruction>(RHS))) | |||
5648 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; | |||
5649 | else | |||
5650 | Upper = APInt::getSignedMinValue(BitWidth) + 1; | |||
5651 | return; | |||
5652 | } | |||
5653 | ||||
5654 | if (R.Flavor == SelectPatternFlavor::SPF_NABS) { | |||
5655 | // The result of -abs(X) is <= 0. | |||
5656 | Lower = APInt::getSignedMinValue(BitWidth); | |||
5657 | Upper = APInt(BitWidth, 1); | |||
5658 | return; | |||
5659 | } | |||
5660 | ||||
5661 | const APInt *C; | |||
5662 | if (!match(LHS, m_APInt(C)) && !match(RHS, m_APInt(C))) | |||
5663 | return; | |||
5664 | ||||
5665 | switch (R.Flavor) { | |||
5666 | case SPF_UMIN: | |||
5667 | Upper = *C + 1; | |||
5668 | break; | |||
5669 | case SPF_UMAX: | |||
5670 | Lower = *C; | |||
5671 | break; | |||
5672 | case SPF_SMIN: | |||
5673 | Lower = APInt::getSignedMinValue(BitWidth); | |||
5674 | Upper = *C + 1; | |||
5675 | break; | |||
5676 | case SPF_SMAX: | |||
5677 | Lower = *C; | |||
5678 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; | |||
5679 | break; | |||
5680 | default: | |||
5681 | break; | |||
5682 | } | |||
5683 | } | |||
5684 | ||||
5685 | ConstantRange llvm::computeConstantRange(const Value *V, bool UseInstrInfo) { | |||
5686 | assert(V->getType()->isIntOrIntVectorTy() && "Expected integer instruction")((V->getType()->isIntOrIntVectorTy() && "Expected integer instruction" ) ? static_cast<void> (0) : __assert_fail ("V->getType()->isIntOrIntVectorTy() && \"Expected integer instruction\"" , "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp" , 5686, __PRETTY_FUNCTION__)); | |||
5687 | ||||
5688 | const APInt *C; | |||
5689 | if (match(V, m_APInt(C))) | |||
5690 | return ConstantRange(*C); | |||
5691 | ||||
5692 | InstrInfoQuery IIQ(UseInstrInfo); | |||
5693 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); | |||
5694 | APInt Lower = APInt(BitWidth, 0); | |||
5695 | APInt Upper = APInt(BitWidth, 0); | |||
5696 | if (auto *BO = dyn_cast<BinaryOperator>(V)) | |||
5697 | setLimitsForBinOp(*BO, Lower, Upper, IIQ); | |||
5698 | else if (auto *II = dyn_cast<IntrinsicInst>(V)) | |||
5699 | setLimitsForIntrinsic(*II, Lower, Upper); | |||
5700 | else if (auto *SI = dyn_cast<SelectInst>(V)) | |||
5701 | setLimitsForSelectPattern(*SI, Lower, Upper, IIQ); | |||
5702 | ||||
5703 | ConstantRange CR = ConstantRange::getNonEmpty(Lower, Upper); | |||
5704 | ||||
5705 | if (auto *I = dyn_cast<Instruction>(V)) | |||
5706 | if (auto *Range = IIQ.getMetadata(I, LLVMContext::MD_range)) | |||
5707 | CR = CR.intersectWith(getConstantRangeFromMetadata(*Range)); | |||
5708 | ||||
5709 | return CR; | |||
5710 | } | |||
5711 | ||||
5712 | static Optional<int64_t> | |||
5713 | getOffsetFromIndex(const GEPOperator *GEP, unsigned Idx, const DataLayout &DL) { | |||
5714 | // Skip over the first indices. | |||
5715 | gep_type_iterator GTI = gep_type_begin(GEP); | |||
5716 | for (unsigned i = 1; i != Idx; ++i, ++GTI) | |||
5717 | /*skip along*/; | |||
5718 | ||||
5719 | // Compute the offset implied by the rest of the indices. | |||
5720 | int64_t Offset = 0; | |||
5721 | for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { | |||
5722 | ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i)); | |||
5723 | if (!OpC) | |||
5724 | return None; | |||
5725 | if (OpC->isZero()) | |||
5726 | continue; // No offset. | |||
5727 | ||||
5728 | // Handle struct indices, which add their field offset to the pointer. | |||
5729 | if (StructType *STy = GTI.getStructTypeOrNull()) { | |||
5730 | Offset += DL.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); | |||
5731 | continue; | |||
5732 | } | |||
5733 | ||||
5734 | // Otherwise, we have a sequential type like an array or vector. Multiply | |||
5735 | // the index by the ElementSize. | |||
5736 | uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType()); | |||
5737 | Offset += Size * OpC->getSExtValue(); | |||
5738 | } | |||
5739 | ||||
5740 | return Offset; | |||
5741 | } | |||
5742 | ||||
5743 | Optional<int64_t> llvm::isPointerOffset(const Value *Ptr1, const Value *Ptr2, | |||
5744 | const DataLayout &DL) { | |||
5745 | Ptr1 = Ptr1->stripPointerCasts(); | |||
5746 | Ptr2 = Ptr2->stripPointerCasts(); | |||
5747 | ||||
5748 | // Handle the trivial case first. | |||
5749 | if (Ptr1 == Ptr2) { | |||
5750 | return 0; | |||
5751 | } | |||
5752 | ||||
5753 | const GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1); | |||
5754 | const GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2); | |||
5755 | ||||
5756 | // If one pointer is a GEP and the other isn't, then see if the GEP is a | |||
5757 | // constant offset from the base, as in "P" and "gep P, 1". | |||
5758 | if (GEP1 && !GEP2 && GEP1->getOperand(0)->stripPointerCasts() == Ptr2) { | |||
5759 | auto Offset = getOffsetFromIndex(GEP1, 1, DL); | |||
5760 | if (!Offset) | |||
5761 | return None; | |||
5762 | return -*Offset; | |||
5763 | } | |||
5764 | ||||
5765 | if (GEP2 && !GEP1 && GEP2->getOperand(0)->stripPointerCasts() == Ptr1) { | |||
5766 | return getOffsetFromIndex(GEP2, 1, DL); | |||
5767 | } | |||
5768 | ||||
5769 | // Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical | |||
5770 | // base. After that base, they may have some number of common (and | |||
5771 | // potentially variable) indices. After that they handle some constant | |||
5772 | // offset, which determines their offset from each other. At this point, we | |||
5773 | // handle no other case. | |||
5774 | if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0)) | |||
5775 | return None; | |||
5776 | ||||
5777 | // Skip any common indices and track the GEP types. | |||
5778 | unsigned Idx = 1; | |||
5779 | for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx) | |||
5780 | if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx)) | |||
5781 | break; | |||
5782 | ||||
5783 | auto Offset1 = getOffsetFromIndex(GEP1, Idx, DL); | |||
5784 | auto Offset2 = getOffsetFromIndex(GEP2, Idx, DL); | |||
5785 | if (!Offset1 || !Offset2) | |||
5786 | return None; | |||
5787 | return *Offset2 - *Offset1; | |||
5788 | } |
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/None.h" | ||||||
18 | #include "llvm/ADT/Optional.h" | ||||||
19 | #include "llvm/IR/Constants.h" | ||||||
20 | #include "llvm/IR/Instruction.h" | ||||||
21 | #include "llvm/IR/Type.h" | ||||||
22 | #include "llvm/IR/Value.h" | ||||||
23 | #include "llvm/Support/Casting.h" | ||||||
24 | #include <cstddef> | ||||||
25 | |||||||
26 | namespace llvm { | ||||||
27 | |||||||
28 | /// This is a utility class that provides an abstraction for the common | ||||||
29 | /// functionality between Instructions and ConstantExprs. | ||||||
30 | class Operator : public User { | ||||||
31 | public: | ||||||
32 | // The Operator class is intended to be used as a utility, and is never itself | ||||||
33 | // instantiated. | ||||||
34 | Operator() = delete; | ||||||
35 | ~Operator() = delete; | ||||||
36 | |||||||
37 | void *operator new(size_t s) = delete; | ||||||
38 | |||||||
39 | /// Return the opcode for this Instruction or ConstantExpr. | ||||||
40 | unsigned getOpcode() const { | ||||||
41 | if (const Instruction *I
| ||||||
42 | return I->getOpcode(); | ||||||
43 | return cast<ConstantExpr>(this)->getOpcode(); | ||||||
44 | } | ||||||
45 | |||||||
46 | /// If V is an Instruction or ConstantExpr, return its opcode. | ||||||
47 | /// Otherwise return UserOp1. | ||||||
48 | static unsigned getOpcode(const Value *V) { | ||||||
49 | if (const Instruction *I = dyn_cast<Instruction>(V)) | ||||||
50 | return I->getOpcode(); | ||||||
51 | if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) | ||||||
52 | return CE->getOpcode(); | ||||||
53 | return Instruction::UserOp1; | ||||||
54 | } | ||||||
55 | |||||||
56 | static bool classof(const Instruction *) { return true; } | ||||||
57 | static bool classof(const ConstantExpr *) { return true; } | ||||||
58 | static bool classof(const Value *V) { | ||||||
59 | return isa<Instruction>(V) || isa<ConstantExpr>(V); | ||||||
60 | } | ||||||
61 | }; | ||||||
62 | |||||||
63 | /// Utility class for integer operators which may exhibit overflow - Add, Sub, | ||||||
64 | /// Mul, and Shl. It does not include SDiv, despite that operator having the | ||||||
65 | /// potential for overflow. | ||||||
66 | class OverflowingBinaryOperator : public Operator { | ||||||
67 | public: | ||||||
68 | enum { | ||||||
69 | NoUnsignedWrap = (1 << 0), | ||||||
70 | NoSignedWrap = (1 << 1) | ||||||
71 | }; | ||||||
72 | |||||||
73 | private: | ||||||
74 | friend class Instruction; | ||||||
75 | friend class ConstantExpr; | ||||||
76 | |||||||
77 | void setHasNoUnsignedWrap(bool B) { | ||||||
78 | SubclassOptionalData = | ||||||
79 | (SubclassOptionalData & ~NoUnsignedWrap) | (B * NoUnsignedWrap); | ||||||
80 | } | ||||||
81 | void setHasNoSignedWrap(bool B) { | ||||||
82 | SubclassOptionalData = | ||||||
83 | (SubclassOptionalData & ~NoSignedWrap) | (B * NoSignedWrap); | ||||||
84 | } | ||||||
85 | |||||||
86 | public: | ||||||
87 | /// Test whether this operation is known to never | ||||||
88 | /// undergo unsigned overflow, aka the nuw property. | ||||||
89 | bool hasNoUnsignedWrap() const { | ||||||
90 | return SubclassOptionalData & NoUnsignedWrap; | ||||||
91 | } | ||||||
92 | |||||||
93 | /// Test whether this operation is known to never | ||||||
94 | /// undergo signed overflow, aka the nsw property. | ||||||
95 | bool hasNoSignedWrap() const { | ||||||
96 | return (SubclassOptionalData & NoSignedWrap) != 0; | ||||||
97 | } | ||||||
98 | |||||||
99 | static bool classof(const Instruction *I) { | ||||||
100 | return I->getOpcode() == Instruction::Add || | ||||||
101 | I->getOpcode() == Instruction::Sub || | ||||||
102 | I->getOpcode() == Instruction::Mul || | ||||||
103 | I->getOpcode() == Instruction::Shl; | ||||||
104 | } | ||||||
105 | static bool classof(const ConstantExpr *CE) { | ||||||
106 | return CE->getOpcode() == Instruction::Add || | ||||||
107 | CE->getOpcode() == Instruction::Sub || | ||||||
108 | CE->getOpcode() == Instruction::Mul || | ||||||
109 | CE->getOpcode() == Instruction::Shl; | ||||||
110 | } | ||||||
111 | static bool classof(const Value *V) { | ||||||
112 | return (isa<Instruction>(V) && classof(cast<Instruction>(V))) || | ||||||
113 | (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V))); | ||||||
114 | } | ||||||
115 | }; | ||||||
116 | |||||||
117 | /// A udiv or sdiv instruction, which can be marked as "exact", | ||||||
118 | /// indicating that no bits are destroyed. | ||||||
119 | class PossiblyExactOperator : public Operator { | ||||||
120 | public: | ||||||
121 | enum { | ||||||
122 | IsExact = (1 << 0) | ||||||
123 | }; | ||||||
124 | |||||||
125 | private: | ||||||
126 | friend class Instruction; | ||||||
127 | friend class ConstantExpr; | ||||||
128 | |||||||
129 | void setIsExact(bool B) { | ||||||
130 | SubclassOptionalData = (SubclassOptionalData & ~IsExact) | (B * IsExact); | ||||||
131 | } | ||||||
132 | |||||||
133 | public: | ||||||
134 | /// Test whether this division is known to be exact, with zero remainder. | ||||||
135 | bool isExact() const { | ||||||
136 | return SubclassOptionalData & IsExact; | ||||||
137 | } | ||||||
138 | |||||||
139 | static bool isPossiblyExactOpcode(unsigned OpC) { | ||||||
140 | return OpC == Instruction::SDiv || | ||||||
141 | OpC == Instruction::UDiv || | ||||||
142 | OpC == Instruction::AShr || | ||||||
143 | OpC == Instruction::LShr; | ||||||
144 | } | ||||||
145 | |||||||
146 | static bool classof(const ConstantExpr *CE) { | ||||||
147 | return isPossiblyExactOpcode(CE->getOpcode()); | ||||||
148 | } | ||||||
149 | static bool classof(const Instruction *I) { | ||||||
150 | return isPossiblyExactOpcode(I->getOpcode()); | ||||||
151 | } | ||||||
152 | static bool classof(const Value *V) { | ||||||
153 | return (isa<Instruction>(V) && classof(cast<Instruction>(V))) || | ||||||
154 | (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V))); | ||||||
155 | } | ||||||
156 | }; | ||||||
157 | |||||||
158 | /// Convenience struct for specifying and reasoning about fast-math flags. | ||||||
159 | class FastMathFlags { | ||||||
160 | private: | ||||||
161 | friend class FPMathOperator; | ||||||
162 | |||||||
163 | unsigned Flags = 0; | ||||||
164 | |||||||
165 | FastMathFlags(unsigned F) { | ||||||
166 | // If all 7 bits are set, turn this into -1. If the number of bits grows, | ||||||
167 | // this must be updated. This is intended to provide some forward binary | ||||||
168 | // compatibility insurance for the meaning of 'fast' in case bits are added. | ||||||
169 | if (F == 0x7F) Flags = ~0U; | ||||||
170 | else Flags = F; | ||||||
171 | } | ||||||
172 | |||||||
173 | public: | ||||||
174 | // This is how the bits are used in Value::SubclassOptionalData so they | ||||||
175 | // should fit there too. | ||||||
176 | // WARNING: We're out of space. SubclassOptionalData only has 7 bits. New | ||||||
177 | // functionality will require a change in how this information is stored. | ||||||
178 | enum { | ||||||
179 | AllowReassoc = (1 << 0), | ||||||
180 | NoNaNs = (1 << 1), | ||||||
181 | NoInfs = (1 << 2), | ||||||
182 | NoSignedZeros = (1 << 3), | ||||||
183 | AllowReciprocal = (1 << 4), | ||||||
184 | AllowContract = (1 << 5), | ||||||
185 | ApproxFunc = (1 << 6) | ||||||
186 | }; | ||||||
187 | |||||||
188 | FastMathFlags() = default; | ||||||
189 | |||||||
190 | static FastMathFlags getFast() { | ||||||
191 | FastMathFlags FMF; | ||||||
192 | FMF.setFast(); | ||||||
193 | return FMF; | ||||||
194 | } | ||||||
195 | |||||||
196 | bool any() const { return Flags != 0; } | ||||||
197 | bool none() const { return Flags == 0; } | ||||||
198 | bool all() const { return Flags == ~0U; } | ||||||
199 | |||||||
200 | void clear() { Flags = 0; } | ||||||
201 | void set() { Flags = ~0U; } | ||||||
202 | |||||||
203 | /// Flag queries | ||||||
204 | bool allowReassoc() const { return 0 != (Flags & AllowReassoc); } | ||||||
205 | bool noNaNs() const { return 0 != (Flags & NoNaNs); } | ||||||
206 | bool noInfs() const { return 0 != (Flags & NoInfs); } | ||||||
207 | bool noSignedZeros() const { return 0 != (Flags & NoSignedZeros); } | ||||||
208 | bool allowReciprocal() const { return 0 != (Flags & AllowReciprocal); } | ||||||
209 | bool allowContract() const { return 0 != (Flags & AllowContract); } | ||||||
210 | bool approxFunc() const { return 0 != (Flags & ApproxFunc); } | ||||||
211 | /// 'Fast' means all bits are set. | ||||||
212 | bool isFast() const { return all(); } | ||||||
213 | |||||||
214 | /// Flag setters | ||||||
215 | void setAllowReassoc(bool B = true) { | ||||||
216 | Flags = (Flags & ~AllowReassoc) | B * AllowReassoc; | ||||||
217 | } | ||||||
218 | void setNoNaNs(bool B = true) { | ||||||
219 | Flags = (Flags & ~NoNaNs) | B * NoNaNs; | ||||||
220 | } | ||||||
221 | void setNoInfs(bool B = true) { | ||||||
222 | Flags = (Flags & ~NoInfs) | B * NoInfs; | ||||||
223 | } | ||||||
224 | void setNoSignedZeros(bool B = true) { | ||||||
225 | Flags = (Flags & ~NoSignedZeros) | B * NoSignedZeros; | ||||||
226 | } | ||||||
227 | void setAllowReciprocal(bool B = true) { | ||||||
228 | Flags = (Flags & ~AllowReciprocal) | B * AllowReciprocal; | ||||||
229 | } | ||||||
230 | void setAllowContract(bool B = true) { | ||||||
231 | Flags = (Flags & ~AllowContract) | B * AllowContract; | ||||||
232 | } | ||||||
233 | void setApproxFunc(bool B = true) { | ||||||
234 | Flags = (Flags & ~ApproxFunc) | B * ApproxFunc; | ||||||
235 | } | ||||||
236 | void setFast(bool B = true) { B ? set() : clear(); } | ||||||
237 | |||||||
238 | void operator&=(const FastMathFlags &OtherFlags) { | ||||||
239 | Flags &= OtherFlags.Flags; | ||||||
240 | } | ||||||
241 | }; | ||||||
242 | |||||||
243 | /// Utility class for floating point operations which can have | ||||||
244 | /// information about relaxed accuracy requirements attached to them. | ||||||
245 | class FPMathOperator : public Operator { | ||||||
246 | private: | ||||||
247 | friend class Instruction; | ||||||
248 | |||||||
249 | /// 'Fast' means all bits are set. | ||||||
250 | void setFast(bool B) { | ||||||
251 | setHasAllowReassoc(B); | ||||||
252 | setHasNoNaNs(B); | ||||||
253 | setHasNoInfs(B); | ||||||
254 | setHasNoSignedZeros(B); | ||||||
255 | setHasAllowReciprocal(B); | ||||||
256 | setHasAllowContract(B); | ||||||
257 | setHasApproxFunc(B); | ||||||
258 | } | ||||||
259 | |||||||
260 | void setHasAllowReassoc(bool B) { | ||||||
261 | SubclassOptionalData = | ||||||
262 | (SubclassOptionalData & ~FastMathFlags::AllowReassoc) | | ||||||
263 | (B * FastMathFlags::AllowReassoc); | ||||||
264 | } | ||||||
265 | |||||||
266 | void setHasNoNaNs(bool B) { | ||||||
267 | SubclassOptionalData = | ||||||
268 | (SubclassOptionalData & ~FastMathFlags::NoNaNs) | | ||||||
269 | (B * FastMathFlags::NoNaNs); | ||||||
270 | } | ||||||
271 | |||||||
272 | void setHasNoInfs(bool B) { | ||||||
273 | SubclassOptionalData = | ||||||
274 | (SubclassOptionalData & ~FastMathFlags::NoInfs) | | ||||||
275 | (B * FastMathFlags::NoInfs); | ||||||
276 | } | ||||||
277 | |||||||
278 | void setHasNoSignedZeros(bool B) { | ||||||
279 | SubclassOptionalData = | ||||||
280 | (SubclassOptionalData & ~FastMathFlags::NoSignedZeros) | | ||||||
281 | (B * FastMathFlags::NoSignedZeros); | ||||||
282 | } | ||||||
283 | |||||||
284 | void setHasAllowReciprocal(bool B) { | ||||||
285 | SubclassOptionalData = | ||||||
286 | (SubclassOptionalData & ~FastMathFlags::AllowReciprocal) | | ||||||
287 | (B * FastMathFlags::AllowReciprocal); | ||||||
288 | } | ||||||
289 | |||||||
290 | void setHasAllowContract(bool B) { | ||||||
291 | SubclassOptionalData = | ||||||
292 | (SubclassOptionalData & ~FastMathFlags::AllowContract) | | ||||||
293 | (B * FastMathFlags::AllowContract); | ||||||
294 | } | ||||||
295 | |||||||
296 | void setHasApproxFunc(bool B) { | ||||||
297 | SubclassOptionalData = | ||||||
298 | (SubclassOptionalData & ~FastMathFlags::ApproxFunc) | | ||||||
299 | (B * FastMathFlags::ApproxFunc); | ||||||
300 | } | ||||||
301 | |||||||
302 | /// Convenience function for setting multiple fast-math flags. | ||||||
303 | /// FMF is a mask of the bits to set. | ||||||
304 | void setFastMathFlags(FastMathFlags FMF) { | ||||||
305 | SubclassOptionalData |= FMF.Flags; | ||||||
306 | } | ||||||
307 | |||||||
308 | /// Convenience function for copying all fast-math flags. | ||||||
309 | /// All values in FMF are transferred to this operator. | ||||||
310 | void copyFastMathFlags(FastMathFlags FMF) { | ||||||
311 | SubclassOptionalData = FMF.Flags; | ||||||
312 | } | ||||||
313 | |||||||
314 | public: | ||||||
315 | /// Test if this operation allows all non-strict floating-point transforms. | ||||||
316 | bool isFast() const { | ||||||
317 | return ((SubclassOptionalData & FastMathFlags::AllowReassoc) != 0 && | ||||||
318 | (SubclassOptionalData & FastMathFlags::NoNaNs) != 0 && | ||||||
319 | (SubclassOptionalData & FastMathFlags::NoInfs) != 0 && | ||||||
320 | (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0 && | ||||||
321 | (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0 && | ||||||
322 | (SubclassOptionalData & FastMathFlags::AllowContract) != 0 && | ||||||
323 | (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0); | ||||||
324 | } | ||||||
325 | |||||||
326 | /// Test if this operation may be simplified with reassociative transforms. | ||||||
327 | bool hasAllowReassoc() const { | ||||||
328 | return (SubclassOptionalData & FastMathFlags::AllowReassoc) != 0; | ||||||
329 | } | ||||||
330 | |||||||
331 | /// Test if this operation's arguments and results are assumed not-NaN. | ||||||
332 | bool hasNoNaNs() const { | ||||||
333 | return (SubclassOptionalData & FastMathFlags::NoNaNs) != 0; | ||||||
334 | } | ||||||
335 | |||||||
336 | /// Test if this operation's arguments and results are assumed not-infinite. | ||||||
337 | bool hasNoInfs() const { | ||||||
338 | return (SubclassOptionalData & FastMathFlags::NoInfs) != 0; | ||||||
339 | } | ||||||
340 | |||||||
341 | /// Test if this operation can ignore the sign of zero. | ||||||
342 | bool hasNoSignedZeros() const { | ||||||
343 | return (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0; | ||||||
344 | } | ||||||
345 | |||||||
346 | /// Test if this operation can use reciprocal multiply instead of division. | ||||||
347 | bool hasAllowReciprocal() const { | ||||||
348 | return (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0; | ||||||
349 | } | ||||||
350 | |||||||
351 | /// Test if this operation can be floating-point contracted (FMA). | ||||||
352 | bool hasAllowContract() const { | ||||||
353 | return (SubclassOptionalData & FastMathFlags::AllowContract) != 0; | ||||||
354 | } | ||||||
355 | |||||||
356 | /// Test if this operation allows approximations of math library functions or | ||||||
357 | /// intrinsics. | ||||||
358 | bool hasApproxFunc() const { | ||||||
359 | return (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0; | ||||||
360 | } | ||||||
361 | |||||||
362 | /// Convenience function for getting all the fast-math flags | ||||||
363 | FastMathFlags getFastMathFlags() const { | ||||||
364 | return FastMathFlags(SubclassOptionalData); | ||||||
365 | } | ||||||
366 | |||||||
367 | /// Get the maximum error permitted by this operation in ULPs. An accuracy of | ||||||
368 | /// 0.0 means that the operation should be performed with the default | ||||||
369 | /// precision. | ||||||
370 | float getFPAccuracy() const; | ||||||
371 | |||||||
372 | static bool classof(const Value *V) { | ||||||
373 | unsigned Opcode; | ||||||
374 | if (auto *I = dyn_cast<Instruction>(V)) | ||||||
375 | Opcode = I->getOpcode(); | ||||||
376 | else if (auto *CE = dyn_cast<ConstantExpr>(V)) | ||||||
377 | Opcode = CE->getOpcode(); | ||||||
378 | else | ||||||
379 | return false; | ||||||
380 | |||||||
381 | switch (Opcode) { | ||||||
382 | case Instruction::FCmp: | ||||||
383 | return true; | ||||||
384 | // non math FP Operators (no FMF) | ||||||
385 | case Instruction::ExtractElement: | ||||||
386 | case Instruction::ShuffleVector: | ||||||
387 | case Instruction::InsertElement: | ||||||
388 | case Instruction::PHI: | ||||||
389 | return false; | ||||||
390 | default: | ||||||
391 | return V->getType()->isFPOrFPVectorTy(); | ||||||
392 | } | ||||||
393 | } | ||||||
394 | }; | ||||||
395 | |||||||
396 | /// A helper template for defining operators for individual opcodes. | ||||||
397 | template<typename SuperClass, unsigned Opc> | ||||||
398 | class ConcreteOperator : public SuperClass { | ||||||
399 | public: | ||||||
400 | static bool classof(const Instruction *I) { | ||||||
401 | return I->getOpcode() == Opc; | ||||||
402 | } | ||||||
403 | static bool classof(const ConstantExpr *CE) { | ||||||
404 | return CE->getOpcode() == Opc; | ||||||
405 | } | ||||||
406 | static bool classof(const Value *V) { | ||||||
407 | return (isa<Instruction>(V) && classof(cast<Instruction>(V))) || | ||||||
408 | (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V))); | ||||||
409 | } | ||||||
410 | }; | ||||||
411 | |||||||
412 | class AddOperator | ||||||
413 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Add> { | ||||||
414 | }; | ||||||
415 | class SubOperator | ||||||
416 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Sub> { | ||||||
417 | }; | ||||||
418 | class MulOperator | ||||||
419 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Mul> { | ||||||
420 | }; | ||||||
421 | class ShlOperator | ||||||
422 | : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Shl> { | ||||||
423 | }; | ||||||
424 | |||||||
425 | class SDivOperator | ||||||
426 | : public ConcreteOperator<PossiblyExactOperator, Instruction::SDiv> { | ||||||
427 | }; | ||||||
428 | class UDivOperator | ||||||
429 | : public ConcreteOperator<PossiblyExactOperator, Instruction::UDiv> { | ||||||
430 | }; | ||||||
431 | class AShrOperator | ||||||
432 | : public ConcreteOperator<PossiblyExactOperator, Instruction::AShr> { | ||||||
433 | }; | ||||||
434 | class LShrOperator | ||||||
435 | : public ConcreteOperator<PossiblyExactOperator, Instruction::LShr> { | ||||||
436 | }; | ||||||
437 | |||||||
438 | class ZExtOperator : public ConcreteOperator<Operator, Instruction::ZExt> {}; | ||||||
439 | |||||||
440 | class GEPOperator | ||||||
441 | : public ConcreteOperator<Operator, Instruction::GetElementPtr> { | ||||||
442 | friend class GetElementPtrInst; | ||||||
443 | friend class ConstantExpr; | ||||||
444 | |||||||
445 | enum { | ||||||
446 | IsInBounds = (1 << 0), | ||||||
447 | // InRangeIndex: bits 1-6 | ||||||
448 | }; | ||||||
449 | |||||||
450 | void setIsInBounds(bool B) { | ||||||
451 | SubclassOptionalData = | ||||||
452 | (SubclassOptionalData & ~IsInBounds) | (B * IsInBounds); | ||||||
453 | } | ||||||
454 | |||||||
455 | public: | ||||||
456 | /// Test whether this is an inbounds GEP, as defined by LangRef.html. | ||||||
457 | bool isInBounds() const { | ||||||
458 | return SubclassOptionalData & IsInBounds; | ||||||
459 | } | ||||||
460 | |||||||
461 | /// Returns the offset of the index with an inrange attachment, or None if | ||||||
462 | /// none. | ||||||
463 | Optional<unsigned> getInRangeIndex() const { | ||||||
464 | if (SubclassOptionalData >> 1 == 0) return None; | ||||||
465 | return (SubclassOptionalData >> 1) - 1; | ||||||
466 | } | ||||||
467 | |||||||
468 | inline op_iterator idx_begin() { return op_begin()+1; } | ||||||
469 | inline const_op_iterator idx_begin() const { return op_begin()+1; } | ||||||
470 | inline op_iterator idx_end() { return op_end(); } | ||||||
471 | inline const_op_iterator idx_end() const { return op_end(); } | ||||||
472 | |||||||
473 | Value *getPointerOperand() { | ||||||
474 | return getOperand(0); | ||||||
475 | } | ||||||
476 | const Value *getPointerOperand() const { | ||||||
477 | return getOperand(0); | ||||||
478 | } | ||||||
479 | static unsigned getPointerOperandIndex() { | ||||||
480 | return 0U; // get index for modifying correct operand | ||||||
481 | } | ||||||
482 | |||||||
483 | /// Method to return the pointer operand as a PointerType. | ||||||
484 | Type *getPointerOperandType() const { | ||||||
485 | return getPointerOperand()->getType(); | ||||||
486 | } | ||||||
487 | |||||||
488 | Type *getSourceElementType() const; | ||||||
489 | Type *getResultElementType() const; | ||||||
490 | |||||||
491 | /// Method to return the address space of the pointer operand. | ||||||
492 | unsigned getPointerAddressSpace() const { | ||||||
493 | return getPointerOperandType()->getPointerAddressSpace(); | ||||||
494 | } | ||||||
495 | |||||||
496 | unsigned getNumIndices() const { // Note: always non-negative | ||||||
497 | return getNumOperands() - 1; | ||||||
498 | } | ||||||
499 | |||||||
500 | bool hasIndices() const { | ||||||
501 | return getNumOperands() > 1; | ||||||
502 | } | ||||||
503 | |||||||
504 | /// Return true if all of the indices of this GEP are zeros. | ||||||
505 | /// If so, the result pointer and the first operand have the same | ||||||
506 | /// value, just potentially different types. | ||||||
507 | bool hasAllZeroIndices() const { | ||||||
508 | for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) { | ||||||
509 | if (ConstantInt *C = dyn_cast<ConstantInt>(I)) | ||||||
510 | if (C->isZero()) | ||||||
511 | continue; | ||||||
512 | return false; | ||||||
513 | } | ||||||
514 | return true; | ||||||
515 | } | ||||||
516 | |||||||
517 | /// Return true if all of the indices of this GEP are constant integers. | ||||||
518 | /// If so, the result pointer and the first operand have | ||||||
519 | /// a constant offset between them. | ||||||
520 | bool hasAllConstantIndices() const { | ||||||
521 | for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) { | ||||||
522 | if (!isa<ConstantInt>(I)) | ||||||
523 | return false; | ||||||
524 | } | ||||||
525 | return true; | ||||||
526 | } | ||||||
527 | |||||||
528 | unsigned countNonConstantIndices() const { | ||||||
529 | return count_if(make_range(idx_begin(), idx_end()), [](const Use& use) { | ||||||
530 | return !isa<ConstantInt>(*use); | ||||||
531 | }); | ||||||
532 | } | ||||||
533 | |||||||
534 | /// Accumulate the constant address offset of this GEP if possible. | ||||||
535 | /// | ||||||
536 | /// This routine accepts an APInt into which it will accumulate the constant | ||||||
537 | /// offset of this GEP if the GEP is in fact constant. If the GEP is not | ||||||
538 | /// all-constant, it returns false and the value of the offset APInt is | ||||||
539 | /// undefined (it is *not* preserved!). The APInt passed into this routine | ||||||
540 | /// must be at exactly as wide as the IntPtr type for the address space of the | ||||||
541 | /// base GEP pointer. | ||||||
542 | bool accumulateConstantOffset(const DataLayout &DL, APInt &Offset) const; | ||||||
543 | }; | ||||||
544 | |||||||
545 | class PtrToIntOperator | ||||||
546 | : public ConcreteOperator<Operator, Instruction::PtrToInt> { | ||||||
547 | friend class PtrToInt; | ||||||
548 | friend class ConstantExpr; | ||||||
549 | |||||||
550 | public: | ||||||
551 | Value *getPointerOperand() { | ||||||
552 | return getOperand(0); | ||||||
553 | } | ||||||
554 | const Value *getPointerOperand() const { | ||||||
555 | return getOperand(0); | ||||||
556 | } | ||||||
557 | |||||||
558 | static unsigned getPointerOperandIndex() { | ||||||
559 | return 0U; // get index for modifying correct operand | ||||||
560 | } | ||||||
561 | |||||||
562 | /// Method to return the pointer operand as a PointerType. | ||||||
563 | Type *getPointerOperandType() const { | ||||||
564 | return getPointerOperand()->getType(); | ||||||
565 | } | ||||||
566 | |||||||
567 | /// Method to return the address space of the pointer operand. | ||||||
568 | unsigned getPointerAddressSpace() const { | ||||||
569 | return cast<PointerType>(getPointerOperandType())->getAddressSpace(); | ||||||
570 | } | ||||||
571 | }; | ||||||
572 | |||||||
573 | class BitCastOperator | ||||||
574 | : public ConcreteOperator<Operator, Instruction::BitCast> { | ||||||
575 | friend class BitCastInst; | ||||||
576 | friend class ConstantExpr; | ||||||
577 | |||||||
578 | public: | ||||||
579 | Type *getSrcTy() const { | ||||||
580 | return getOperand(0)->getType(); | ||||||
581 | } | ||||||
582 | |||||||
583 | Type *getDestTy() const { | ||||||
584 | return getType(); | ||||||
585 | } | ||||||
586 | }; | ||||||
587 | |||||||
588 | } // end namespace llvm | ||||||
589 | |||||||
590 | #endif // LLVM_IR_OPERATOR_H |
1 | //===- llvm/Analysis/ValueTracking.h - Walk computations --------*- 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 contains routines that help analyze properties that chains of | |||
10 | // computations have. | |||
11 | // | |||
12 | //===----------------------------------------------------------------------===// | |||
13 | ||||
14 | #ifndef LLVM_ANALYSIS_VALUETRACKING_H | |||
15 | #define LLVM_ANALYSIS_VALUETRACKING_H | |||
16 | ||||
17 | #include "llvm/ADT/ArrayRef.h" | |||
18 | #include "llvm/ADT/Optional.h" | |||
19 | #include "llvm/ADT/SmallSet.h" | |||
20 | #include "llvm/IR/CallSite.h" | |||
21 | #include "llvm/IR/Constants.h" | |||
22 | #include "llvm/IR/DataLayout.h" | |||
23 | #include "llvm/IR/Instruction.h" | |||
24 | #include "llvm/IR/Intrinsics.h" | |||
25 | #include <cassert> | |||
26 | #include <cstdint> | |||
27 | ||||
28 | namespace llvm { | |||
29 | ||||
30 | class AddOperator; | |||
31 | class APInt; | |||
32 | class AssumptionCache; | |||
33 | class DominatorTree; | |||
34 | class GEPOperator; | |||
35 | class IntrinsicInst; | |||
36 | class WithOverflowInst; | |||
37 | struct KnownBits; | |||
38 | class Loop; | |||
39 | class LoopInfo; | |||
40 | class MDNode; | |||
41 | class OptimizationRemarkEmitter; | |||
42 | class StringRef; | |||
43 | class TargetLibraryInfo; | |||
44 | class Value; | |||
45 | ||||
46 | /// Determine which bits of V are known to be either zero or one and return | |||
47 | /// them in the KnownZero/KnownOne bit sets. | |||
48 | /// | |||
49 | /// This function is defined on values with integer type, values with pointer | |||
50 | /// type, and vectors of integers. In the case | |||
51 | /// where V is a vector, the known zero and known one values are the | |||
52 | /// same width as the vector element, and the bit is set only if it is true | |||
53 | /// for all of the elements in the vector. | |||
54 | void computeKnownBits(const Value *V, KnownBits &Known, | |||
55 | const DataLayout &DL, unsigned Depth = 0, | |||
56 | AssumptionCache *AC = nullptr, | |||
57 | const Instruction *CxtI = nullptr, | |||
58 | const DominatorTree *DT = nullptr, | |||
59 | OptimizationRemarkEmitter *ORE = nullptr, | |||
60 | bool UseInstrInfo = true); | |||
61 | ||||
62 | /// Returns the known bits rather than passing by reference. | |||
63 | KnownBits computeKnownBits(const Value *V, const DataLayout &DL, | |||
64 | unsigned Depth = 0, AssumptionCache *AC = nullptr, | |||
65 | const Instruction *CxtI = nullptr, | |||
66 | const DominatorTree *DT = nullptr, | |||
67 | OptimizationRemarkEmitter *ORE = nullptr, | |||
68 | bool UseInstrInfo = true); | |||
69 | ||||
70 | /// Compute known bits from the range metadata. | |||
71 | /// \p KnownZero the set of bits that are known to be zero | |||
72 | /// \p KnownOne the set of bits that are known to be one | |||
73 | void computeKnownBitsFromRangeMetadata(const MDNode &Ranges, | |||
74 | KnownBits &Known); | |||
75 | ||||
76 | /// Return true if LHS and RHS have no common bits set. | |||
77 | bool haveNoCommonBitsSet(const Value *LHS, const Value *RHS, | |||
78 | const DataLayout &DL, | |||
79 | AssumptionCache *AC = nullptr, | |||
80 | const Instruction *CxtI = nullptr, | |||
81 | const DominatorTree *DT = nullptr, | |||
82 | bool UseInstrInfo = true); | |||
83 | ||||
84 | /// Return true if the given value is known to have exactly one bit set when | |||
85 | /// defined. For vectors return true if every element is known to be a power | |||
86 | /// of two when defined. Supports values with integer or pointer type and | |||
87 | /// vectors of integers. If 'OrZero' is set, then return true if the given | |||
88 | /// value is either a power of two or zero. | |||
89 | bool isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL, | |||
90 | bool OrZero = false, unsigned Depth = 0, | |||
91 | AssumptionCache *AC = nullptr, | |||
92 | const Instruction *CxtI = nullptr, | |||
93 | const DominatorTree *DT = nullptr, | |||
94 | bool UseInstrInfo = true); | |||
95 | ||||
96 | bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI); | |||
97 | ||||
98 | /// Return true if the given value is known to be non-zero when defined. For | |||
99 | /// vectors, return true if every element is known to be non-zero when | |||
100 | /// defined. For pointers, if the context instruction and dominator tree are | |||
101 | /// specified, perform context-sensitive analysis and return true if the | |||
102 | /// pointer couldn't possibly be null at the specified instruction. | |||
103 | /// Supports values with integer or pointer type and vectors of integers. | |||
104 | bool isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth = 0, | |||
105 | AssumptionCache *AC = nullptr, | |||
106 | const Instruction *CxtI = nullptr, | |||
107 | const DominatorTree *DT = nullptr, | |||
108 | bool UseInstrInfo = true); | |||
109 | ||||
110 | /// Return true if the two given values are negation. | |||
111 | /// Currently can recoginze Value pair: | |||
112 | /// 1: <X, Y> if X = sub (0, Y) or Y = sub (0, X) | |||
113 | /// 2: <X, Y> if X = sub (A, B) and Y = sub (B, A) | |||
114 | bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW = false); | |||
115 | ||||
116 | /// Returns true if the give value is known to be non-negative. | |||
117 | bool isKnownNonNegative(const Value *V, const DataLayout &DL, | |||
118 | unsigned Depth = 0, | |||
119 | AssumptionCache *AC = nullptr, | |||
120 | const Instruction *CxtI = nullptr, | |||
121 | const DominatorTree *DT = nullptr, | |||
122 | bool UseInstrInfo = true); | |||
123 | ||||
124 | /// Returns true if the given value is known be positive (i.e. non-negative | |||
125 | /// and non-zero). | |||
126 | bool isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth = 0, | |||
127 | AssumptionCache *AC = nullptr, | |||
128 | const Instruction *CxtI = nullptr, | |||
129 | const DominatorTree *DT = nullptr, | |||
130 | bool UseInstrInfo = true); | |||
131 | ||||
132 | /// Returns true if the given value is known be negative (i.e. non-positive | |||
133 | /// and non-zero). | |||
134 | bool isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth = 0, | |||
135 | AssumptionCache *AC = nullptr, | |||
136 | const Instruction *CxtI = nullptr, | |||
137 | const DominatorTree *DT = nullptr, | |||
138 | bool UseInstrInfo = true); | |||
139 | ||||
140 | /// Return true if the given values are known to be non-equal when defined. | |||
141 | /// Supports scalar integer types only. | |||
142 | bool isKnownNonEqual(const Value *V1, const Value *V2, const DataLayout &DL, | |||
143 | AssumptionCache *AC = nullptr, | |||
144 | const Instruction *CxtI = nullptr, | |||
145 | const DominatorTree *DT = nullptr, | |||
146 | bool UseInstrInfo = true); | |||
147 | ||||
148 | /// Return true if 'V & Mask' is known to be zero. We use this predicate to | |||
149 | /// simplify operations downstream. Mask is known to be zero for bits that V | |||
150 | /// cannot have. | |||
151 | /// | |||
152 | /// This function is defined on values with integer type, values with pointer | |||
153 | /// type, and vectors of integers. In the case | |||
154 | /// where V is a vector, the mask, known zero, and known one values are the | |||
155 | /// same width as the vector element, and the bit is set only if it is true | |||
156 | /// for all of the elements in the vector. | |||
157 | bool MaskedValueIsZero(const Value *V, const APInt &Mask, | |||
158 | const DataLayout &DL, | |||
159 | unsigned Depth = 0, AssumptionCache *AC = nullptr, | |||
160 | const Instruction *CxtI = nullptr, | |||
161 | const DominatorTree *DT = nullptr, | |||
162 | bool UseInstrInfo = true); | |||
163 | ||||
164 | /// Return the number of times the sign bit of the register is replicated into | |||
165 | /// the other bits. We know that at least 1 bit is always equal to the sign | |||
166 | /// bit (itself), but other cases can give us information. For example, | |||
167 | /// immediately after an "ashr X, 2", we know that the top 3 bits are all | |||
168 | /// equal to each other, so we return 3. For vectors, return the number of | |||
169 | /// sign bits for the vector element with the mininum number of known sign | |||
170 | /// bits. | |||
171 | unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL, | |||
172 | unsigned Depth = 0, AssumptionCache *AC = nullptr, | |||
173 | const Instruction *CxtI = nullptr, | |||
174 | const DominatorTree *DT = nullptr, | |||
175 | bool UseInstrInfo = true); | |||
176 | ||||
177 | /// This function computes the integer multiple of Base that equals V. If | |||
178 | /// successful, it returns true and returns the multiple in Multiple. If | |||
179 | /// unsuccessful, it returns false. Also, if V can be simplified to an | |||
180 | /// integer, then the simplified V is returned in Val. Look through sext only | |||
181 | /// if LookThroughSExt=true. | |||
182 | bool ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, | |||
183 | bool LookThroughSExt = false, | |||
184 | unsigned Depth = 0); | |||
185 | ||||
186 | /// Map a call instruction to an intrinsic ID. Libcalls which have equivalent | |||
187 | /// intrinsics are treated as-if they were intrinsics. | |||
188 | Intrinsic::ID getIntrinsicForCallSite(ImmutableCallSite ICS, | |||
189 | const TargetLibraryInfo *TLI); | |||
190 | ||||
191 | /// Return true if we can prove that the specified FP value is never equal to | |||
192 | /// -0.0. | |||
193 | bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI, | |||
194 | unsigned Depth = 0); | |||
195 | ||||
196 | /// Return true if we can prove that the specified FP value is either NaN or | |||
197 | /// never less than -0.0. | |||
198 | /// | |||
199 | /// NaN --> true | |||
200 | /// +0 --> true | |||
201 | /// -0 --> true | |||
202 | /// x > +0 --> true | |||
203 | /// x < -0 --> false | |||
204 | bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI); | |||
205 | ||||
206 | /// Return true if the floating-point scalar value is not a NaN or if the | |||
207 | /// floating-point vector value has no NaN elements. Return false if a value | |||
208 | /// could ever be NaN. | |||
209 | bool isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI, | |||
210 | unsigned Depth = 0); | |||
211 | ||||
212 | /// Return true if we can prove that the specified FP value's sign bit is 0. | |||
213 | /// | |||
214 | /// NaN --> true/false (depending on the NaN's sign bit) | |||
215 | /// +0 --> true | |||
216 | /// -0 --> false | |||
217 | /// x > +0 --> true | |||
218 | /// x < -0 --> false | |||
219 | bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI); | |||
220 | ||||
221 | /// If the specified value can be set by repeating the same byte in memory, | |||
222 | /// return the i8 value that it is represented with. This is true for all i8 | |||
223 | /// values obviously, but is also true for i32 0, i32 -1, i16 0xF0F0, double | |||
224 | /// 0.0 etc. If the value can't be handled with a repeated byte store (e.g. | |||
225 | /// i16 0x1234), return null. If the value is entirely undef and padding, | |||
226 | /// return undef. | |||
227 | Value *isBytewiseValue(Value *V, const DataLayout &DL); | |||
228 | ||||
229 | /// Given an aggregrate and an sequence of indices, see if the scalar value | |||
230 | /// indexed is already around as a register, for example if it were inserted | |||
231 | /// directly into the aggregrate. | |||
232 | /// | |||
233 | /// If InsertBefore is not null, this function will duplicate (modified) | |||
234 | /// insertvalues when a part of a nested struct is extracted. | |||
235 | Value *FindInsertedValue(Value *V, | |||
236 | ArrayRef<unsigned> idx_range, | |||
237 | Instruction *InsertBefore = nullptr); | |||
238 | ||||
239 | /// Analyze the specified pointer to see if it can be expressed as a base | |||
240 | /// pointer plus a constant offset. Return the base and offset to the caller. | |||
241 | /// | |||
242 | /// This is a wrapper around Value::stripAndAccumulateConstantOffsets that | |||
243 | /// creates and later unpacks the required APInt. | |||
244 | inline Value *GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, | |||
245 | const DataLayout &DL, | |||
246 | bool AllowNonInbounds = true) { | |||
247 | APInt OffsetAPInt(DL.getIndexTypeSizeInBits(Ptr->getType()), 0); | |||
248 | Value *Base = | |||
249 | Ptr->stripAndAccumulateConstantOffsets(DL, OffsetAPInt, AllowNonInbounds); | |||
250 | ||||
251 | Offset = OffsetAPInt.getSExtValue(); | |||
252 | return Base; | |||
253 | } | |||
254 | inline const Value * | |||
255 | GetPointerBaseWithConstantOffset(const Value *Ptr, int64_t &Offset, | |||
256 | const DataLayout &DL, | |||
257 | bool AllowNonInbounds = true) { | |||
258 | return GetPointerBaseWithConstantOffset(const_cast<Value *>(Ptr), Offset, DL, | |||
259 | AllowNonInbounds); | |||
260 | } | |||
261 | ||||
262 | /// Returns true if the GEP is based on a pointer to a string (array of | |||
263 | // \p CharSize integers) and is indexing into this string. | |||
264 | bool isGEPBasedOnPointerToString(const GEPOperator *GEP, | |||
265 | unsigned CharSize = 8); | |||
266 | ||||
267 | /// Represents offset+length into a ConstantDataArray. | |||
268 | struct ConstantDataArraySlice { | |||
269 | /// ConstantDataArray pointer. nullptr indicates a zeroinitializer (a valid | |||
270 | /// initializer, it just doesn't fit the ConstantDataArray interface). | |||
271 | const ConstantDataArray *Array; | |||
272 | ||||
273 | /// Slice starts at this Offset. | |||
274 | uint64_t Offset; | |||
275 | ||||
276 | /// Length of the slice. | |||
277 | uint64_t Length; | |||
278 | ||||
279 | /// Moves the Offset and adjusts Length accordingly. | |||
280 | void move(uint64_t Delta) { | |||
281 | assert(Delta < Length)((Delta < Length) ? static_cast<void> (0) : __assert_fail ("Delta < Length", "/build/llvm-toolchain-snapshot-10~svn372306/include/llvm/Analysis/ValueTracking.h" , 281, __PRETTY_FUNCTION__)); | |||
282 | Offset += Delta; | |||
283 | Length -= Delta; | |||
284 | } | |||
285 | ||||
286 | /// Convenience accessor for elements in the slice. | |||
287 | uint64_t operator[](unsigned I) const { | |||
288 | return Array==nullptr ? 0 : Array->getElementAsInteger(I + Offset); | |||
289 | } | |||
290 | }; | |||
291 | ||||
292 | /// Returns true if the value \p V is a pointer into a ConstantDataArray. | |||
293 | /// If successful \p Slice will point to a ConstantDataArray info object | |||
294 | /// with an appropriate offset. | |||
295 | bool getConstantDataArrayInfo(const Value *V, ConstantDataArraySlice &Slice, | |||
296 | unsigned ElementSize, uint64_t Offset = 0); | |||
297 | ||||
298 | /// This function computes the length of a null-terminated C string pointed to | |||
299 | /// by V. If successful, it returns true and returns the string in Str. If | |||
300 | /// unsuccessful, it returns false. This does not include the trailing null | |||
301 | /// character by default. If TrimAtNul is set to false, then this returns any | |||
302 | /// trailing null characters as well as any other characters that come after | |||
303 | /// it. | |||
304 | bool getConstantStringInfo(const Value *V, StringRef &Str, | |||
305 | uint64_t Offset = 0, bool TrimAtNul = true); | |||
306 | ||||
307 | /// If we can compute the length of the string pointed to by the specified | |||
308 | /// pointer, return 'len+1'. If we can't, return 0. | |||
309 | uint64_t GetStringLength(const Value *V, unsigned CharSize = 8); | |||
310 | ||||
311 | /// This function returns call pointer argument that is considered the same by | |||
312 | /// aliasing rules. You CAN'T use it to replace one value with another. If | |||
313 | /// \p MustPreserveNullness is true, the call must preserve the nullness of | |||
314 | /// the pointer. | |||
315 | const Value *getArgumentAliasingToReturnedPointer(const CallBase *Call, | |||
316 | bool MustPreserveNullness); | |||
317 | inline Value * | |||
318 | getArgumentAliasingToReturnedPointer(CallBase *Call, | |||
319 | bool MustPreserveNullness) { | |||
320 | return const_cast<Value *>(getArgumentAliasingToReturnedPointer( | |||
321 | const_cast<const CallBase *>(Call), MustPreserveNullness)); | |||
322 | } | |||
323 | ||||
324 | /// {launder,strip}.invariant.group returns pointer that aliases its argument, | |||
325 | /// and it only captures pointer by returning it. | |||
326 | /// These intrinsics are not marked as nocapture, because returning is | |||
327 | /// considered as capture. The arguments are not marked as returned neither, | |||
328 | /// because it would make it useless. If \p MustPreserveNullness is true, | |||
329 | /// the intrinsic must preserve the nullness of the pointer. | |||
330 | bool isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( | |||
331 | const CallBase *Call, bool MustPreserveNullness); | |||
332 | ||||
333 | /// This method strips off any GEP address adjustments and pointer casts from | |||
334 | /// the specified value, returning the original object being addressed. Note | |||
335 | /// that the returned value has pointer type if the specified value does. If | |||
336 | /// the MaxLookup value is non-zero, it limits the number of instructions to | |||
337 | /// be stripped off. | |||
338 | Value *GetUnderlyingObject(Value *V, const DataLayout &DL, | |||
339 | unsigned MaxLookup = 6); | |||
340 | inline const Value *GetUnderlyingObject(const Value *V, const DataLayout &DL, | |||
341 | unsigned MaxLookup = 6) { | |||
342 | return GetUnderlyingObject(const_cast<Value *>(V), DL, MaxLookup); | |||
343 | } | |||
344 | ||||
345 | /// This method is similar to GetUnderlyingObject except that it can | |||
346 | /// look through phi and select instructions and return multiple objects. | |||
347 | /// | |||
348 | /// If LoopInfo is passed, loop phis are further analyzed. If a pointer | |||
349 | /// accesses different objects in each iteration, we don't look through the | |||
350 | /// phi node. E.g. consider this loop nest: | |||
351 | /// | |||
352 | /// int **A; | |||
353 | /// for (i) | |||
354 | /// for (j) { | |||
355 | /// A[i][j] = A[i-1][j] * B[j] | |||
356 | /// } | |||
357 | /// | |||
358 | /// This is transformed by Load-PRE to stash away A[i] for the next iteration | |||
359 | /// of the outer loop: | |||
360 | /// | |||
361 | /// Curr = A[0]; // Prev_0 | |||
362 | /// for (i: 1..N) { | |||
363 | /// Prev = Curr; // Prev = PHI (Prev_0, Curr) | |||
364 | /// Curr = A[i]; | |||
365 | /// for (j: 0..N) { | |||
366 | /// Curr[j] = Prev[j] * B[j] | |||
367 | /// } | |||
368 | /// } | |||
369 | /// | |||
370 | /// Since A[i] and A[i-1] are independent pointers, getUnderlyingObjects | |||
371 | /// should not assume that Curr and Prev share the same underlying object thus | |||
372 | /// it shouldn't look through the phi above. | |||
373 | void GetUnderlyingObjects(const Value *V, | |||
374 | SmallVectorImpl<const Value *> &Objects, | |||
375 | const DataLayout &DL, LoopInfo *LI = nullptr, | |||
376 | unsigned MaxLookup = 6); | |||
377 | ||||
378 | /// This is a wrapper around GetUnderlyingObjects and adds support for basic | |||
379 | /// ptrtoint+arithmetic+inttoptr sequences. | |||
380 | bool getUnderlyingObjectsForCodeGen(const Value *V, | |||
381 | SmallVectorImpl<Value *> &Objects, | |||
382 | const DataLayout &DL); | |||
383 | ||||
384 | /// Return true if the only users of this pointer are lifetime markers. | |||
385 | bool onlyUsedByLifetimeMarkers(const Value *V); | |||
386 | ||||
387 | /// Return true if speculation of the given load must be suppressed to avoid | |||
388 | /// ordering or interfering with an active sanitizer. If not suppressed, | |||
389 | /// dereferenceability and alignment must be proven separately. Note: This | |||
390 | /// is only needed for raw reasoning; if you use the interface below | |||
391 | /// (isSafeToSpeculativelyExecute), this is handled internally. | |||
392 | bool mustSuppressSpeculation(const LoadInst &LI); | |||
393 | ||||
394 | /// Return true if the instruction does not have any effects besides | |||
395 | /// calculating the result and does not have undefined behavior. | |||
396 | /// | |||
397 | /// This method never returns true for an instruction that returns true for | |||
398 | /// mayHaveSideEffects; however, this method also does some other checks in | |||
399 | /// addition. It checks for undefined behavior, like dividing by zero or | |||
400 | /// loading from an invalid pointer (but not for undefined results, like a | |||
401 | /// shift with a shift amount larger than the width of the result). It checks | |||
402 | /// for malloc and alloca because speculatively executing them might cause a | |||
403 | /// memory leak. It also returns false for instructions related to control | |||
404 | /// flow, specifically terminators and PHI nodes. | |||
405 | /// | |||
406 | /// If the CtxI is specified this method performs context-sensitive analysis | |||
407 | /// and returns true if it is safe to execute the instruction immediately | |||
408 | /// before the CtxI. | |||
409 | /// | |||
410 | /// If the CtxI is NOT specified this method only looks at the instruction | |||
411 | /// itself and its operands, so if this method returns true, it is safe to | |||
412 | /// move the instruction as long as the correct dominance relationships for | |||
413 | /// the operands and users hold. | |||
414 | /// | |||
415 | /// This method can return true for instructions that read memory; | |||
416 | /// for such instructions, moving them may change the resulting value. | |||
417 | bool isSafeToSpeculativelyExecute(const Value *V, | |||
418 | const Instruction *CtxI = nullptr, | |||
419 | const DominatorTree *DT = nullptr); | |||
420 | ||||
421 | /// Returns true if the result or effects of the given instructions \p I | |||
422 | /// depend on or influence global memory. | |||
423 | /// Memory dependence arises for example if the instruction reads from | |||
424 | /// memory or may produce effects or undefined behaviour. Memory dependent | |||
425 | /// instructions generally cannot be reorderd with respect to other memory | |||
426 | /// dependent instructions or moved into non-dominated basic blocks. | |||
427 | /// Instructions which just compute a value based on the values of their | |||
428 | /// operands are not memory dependent. | |||
429 | bool mayBeMemoryDependent(const Instruction &I); | |||
430 | ||||
431 | /// Return true if it is an intrinsic that cannot be speculated but also | |||
432 | /// cannot trap. | |||
433 | bool isAssumeLikeIntrinsic(const Instruction *I); | |||
434 | ||||
435 | /// Return true if it is valid to use the assumptions provided by an | |||
436 | /// assume intrinsic, I, at the point in the control-flow identified by the | |||
437 | /// context instruction, CxtI. | |||
438 | bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI, | |||
439 | const DominatorTree *DT = nullptr); | |||
440 | ||||
441 | enum class OverflowResult { | |||
442 | /// Always overflows in the direction of signed/unsigned min value. | |||
443 | AlwaysOverflowsLow, | |||
444 | /// Always overflows in the direction of signed/unsigned max value. | |||
445 | AlwaysOverflowsHigh, | |||
446 | /// May or may not overflow. | |||
447 | MayOverflow, | |||
448 | /// Never overflows. | |||
449 | NeverOverflows, | |||
450 | }; | |||
451 | ||||
452 | OverflowResult computeOverflowForUnsignedMul(const Value *LHS, | |||
453 | const Value *RHS, | |||
454 | const DataLayout &DL, | |||
455 | AssumptionCache *AC, | |||
456 | const Instruction *CxtI, | |||
457 | const DominatorTree *DT, | |||
458 | bool UseInstrInfo = true); | |||
459 | OverflowResult computeOverflowForSignedMul(const Value *LHS, const Value *RHS, | |||
460 | const DataLayout &DL, | |||
461 | AssumptionCache *AC, | |||
462 | const Instruction *CxtI, | |||
463 | const DominatorTree *DT, | |||
464 | bool UseInstrInfo = true); | |||
465 | OverflowResult computeOverflowForUnsignedAdd(const Value *LHS, | |||
466 | const Value *RHS, | |||
467 | const DataLayout &DL, | |||
468 | AssumptionCache *AC, | |||
469 | const Instruction *CxtI, | |||
470 | const DominatorTree *DT, | |||
471 | bool UseInstrInfo = true); | |||
472 | OverflowResult computeOverflowForSignedAdd(const Value *LHS, const Value *RHS, | |||
473 | const DataLayout &DL, | |||
474 | AssumptionCache *AC = nullptr, | |||
475 | const Instruction *CxtI = nullptr, | |||
476 | const DominatorTree *DT = nullptr); | |||
477 | /// This version also leverages the sign bit of Add if known. | |||
478 | OverflowResult computeOverflowForSignedAdd(const AddOperator *Add, | |||
479 | const DataLayout &DL, | |||
480 | AssumptionCache *AC = nullptr, | |||
481 | const Instruction *CxtI = nullptr, | |||
482 | const DominatorTree *DT = nullptr); | |||
483 | OverflowResult computeOverflowForUnsignedSub(const Value *LHS, const Value *RHS, | |||
484 | const DataLayout &DL, | |||
485 | AssumptionCache *AC, | |||
486 | const Instruction *CxtI, | |||
487 | const DominatorTree *DT); | |||
488 | OverflowResult computeOverflowForSignedSub(const Value *LHS, const Value *RHS, | |||
489 | const DataLayout &DL, | |||
490 | AssumptionCache *AC, | |||
491 | const Instruction *CxtI, | |||
492 | const DominatorTree *DT); | |||
493 | ||||
494 | /// Returns true if the arithmetic part of the \p WO 's result is | |||
495 | /// used only along the paths control dependent on the computation | |||
496 | /// not overflowing, \p WO being an <op>.with.overflow intrinsic. | |||
497 | bool isOverflowIntrinsicNoWrap(const WithOverflowInst *WO, | |||
498 | const DominatorTree &DT); | |||
499 | ||||
500 | ||||
501 | /// Determine the possible constant range of an integer or vector of integer | |||
502 | /// value. This is intended as a cheap, non-recursive check. | |||
503 | ConstantRange computeConstantRange(const Value *V, bool UseInstrInfo = true); | |||
504 | ||||
505 | /// Return true if this function can prove that the instruction I will | |||
506 | /// always transfer execution to one of its successors (including the next | |||
507 | /// instruction that follows within a basic block). E.g. this is not | |||
508 | /// guaranteed for function calls that could loop infinitely. | |||
509 | /// | |||
510 | /// In other words, this function returns false for instructions that may | |||
511 | /// transfer execution or fail to transfer execution in a way that is not | |||
512 | /// captured in the CFG nor in the sequence of instructions within a basic | |||
513 | /// block. | |||
514 | /// | |||
515 | /// Undefined behavior is assumed not to happen, so e.g. division is | |||
516 | /// guaranteed to transfer execution to the following instruction even | |||
517 | /// though division by zero might cause undefined behavior. | |||
518 | bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I); | |||
519 | ||||
520 | /// Returns true if this block does not contain a potential implicit exit. | |||
521 | /// This is equivelent to saying that all instructions within the basic block | |||
522 | /// are guaranteed to transfer execution to their successor within the basic | |||
523 | /// block. This has the same assumptions w.r.t. undefined behavior as the | |||
524 | /// instruction variant of this function. | |||
525 | bool isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB); | |||
526 | ||||
527 | /// Return true if this function can prove that the instruction I | |||
528 | /// is executed for every iteration of the loop L. | |||
529 | /// | |||
530 | /// Note that this currently only considers the loop header. | |||
531 | bool isGuaranteedToExecuteForEveryIteration(const Instruction *I, | |||
532 | const Loop *L); | |||
533 | ||||
534 | /// Return true if this function can prove that I is guaranteed to yield | |||
535 | /// full-poison (all bits poison) if at least one of its operands are | |||
536 | /// full-poison (all bits poison). | |||
537 | /// | |||
538 | /// The exact rules for how poison propagates through instructions have | |||
539 | /// not been settled as of 2015-07-10, so this function is conservative | |||
540 | /// and only considers poison to be propagated in uncontroversial | |||
541 | /// cases. There is no attempt to track values that may be only partially | |||
542 | /// poison. | |||
543 | bool propagatesFullPoison(const Instruction *I); | |||
544 | ||||
545 | /// Return either nullptr or an operand of I such that I will trigger | |||
546 | /// undefined behavior if I is executed and that operand has a full-poison | |||
547 | /// value (all bits poison). | |||
548 | const Value *getGuaranteedNonFullPoisonOp(const Instruction *I); | |||
549 | ||||
550 | /// Return true if the given instruction must trigger undefined behavior. | |||
551 | /// when I is executed with any operands which appear in KnownPoison holding | |||
552 | /// a full-poison value at the point of execution. | |||
553 | bool mustTriggerUB(const Instruction *I, | |||
554 | const SmallSet<const Value *, 16>& KnownPoison); | |||
555 | ||||
556 | /// Return true if this function can prove that if PoisonI is executed | |||
557 | /// and yields a full-poison value (all bits poison), then that will | |||
558 | /// trigger undefined behavior. | |||
559 | /// | |||
560 | /// Note that this currently only considers the basic block that is | |||
561 | /// the parent of I. | |||
562 | bool programUndefinedIfFullPoison(const Instruction *PoisonI); | |||
563 | ||||
564 | /// Specific patterns of select instructions we can match. | |||
565 | enum SelectPatternFlavor { | |||
566 | SPF_UNKNOWN = 0, | |||
567 | SPF_SMIN, /// Signed minimum | |||
568 | SPF_UMIN, /// Unsigned minimum | |||
569 | SPF_SMAX, /// Signed maximum | |||
570 | SPF_UMAX, /// Unsigned maximum | |||
571 | SPF_FMINNUM, /// Floating point minnum | |||
572 | SPF_FMAXNUM, /// Floating point maxnum | |||
573 | SPF_ABS, /// Absolute value | |||
574 | SPF_NABS /// Negated absolute value | |||
575 | }; | |||
576 | ||||
577 | /// Behavior when a floating point min/max is given one NaN and one | |||
578 | /// non-NaN as input. | |||
579 | enum SelectPatternNaNBehavior { | |||
580 | SPNB_NA = 0, /// NaN behavior not applicable. | |||
581 | SPNB_RETURNS_NAN, /// Given one NaN input, returns the NaN. | |||
582 | SPNB_RETURNS_OTHER, /// Given one NaN input, returns the non-NaN. | |||
583 | SPNB_RETURNS_ANY /// Given one NaN input, can return either (or | |||
584 | /// it has been determined that no operands can | |||
585 | /// be NaN). | |||
586 | }; | |||
587 | ||||
588 | struct SelectPatternResult { | |||
589 | SelectPatternFlavor Flavor; | |||
590 | SelectPatternNaNBehavior NaNBehavior; /// Only applicable if Flavor is | |||
591 | /// SPF_FMINNUM or SPF_FMAXNUM. | |||
592 | bool Ordered; /// When implementing this min/max pattern as | |||
593 | /// fcmp; select, does the fcmp have to be | |||
594 | /// ordered? | |||
595 | ||||
596 | /// Return true if \p SPF is a min or a max pattern. | |||
597 | static bool isMinOrMax(SelectPatternFlavor SPF) { | |||
598 | return SPF != SPF_UNKNOWN && SPF != SPF_ABS && SPF != SPF_NABS; | |||
599 | } | |||
600 | }; | |||
601 | ||||
602 | /// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind | |||
603 | /// and providing the out parameter results if we successfully match. | |||
604 | /// | |||
605 | /// For ABS/NABS, LHS will be set to the input to the abs idiom. RHS will be | |||
606 | /// the negation instruction from the idiom. | |||
607 | /// | |||
608 | /// If CastOp is not nullptr, also match MIN/MAX idioms where the type does | |||
609 | /// not match that of the original select. If this is the case, the cast | |||
610 | /// operation (one of Trunc,SExt,Zext) that must be done to transform the | |||
611 | /// type of LHS and RHS into the type of V is returned in CastOp. | |||
612 | /// | |||
613 | /// For example: | |||
614 | /// %1 = icmp slt i32 %a, i32 4 | |||
615 | /// %2 = sext i32 %a to i64 | |||
616 | /// %3 = select i1 %1, i64 %2, i64 4 | |||
617 | /// | |||
618 | /// -> LHS = %a, RHS = i32 4, *CastOp = Instruction::SExt | |||
619 | /// | |||
620 | SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, | |||
621 | Instruction::CastOps *CastOp = nullptr, | |||
622 | unsigned Depth = 0); | |||
623 | inline SelectPatternResult | |||
624 | matchSelectPattern(const Value *V, const Value *&LHS, const Value *&RHS, | |||
625 | Instruction::CastOps *CastOp = nullptr) { | |||
626 | Value *L = const_cast<Value*>(LHS); | |||
| ||||
627 | Value *R = const_cast<Value*>(RHS); | |||
628 | auto Result = matchSelectPattern(const_cast<Value*>(V), L, R); | |||
629 | LHS = L; | |||
630 | RHS = R; | |||
631 | return Result; | |||
632 | } | |||
633 | ||||
634 | /// Determine the pattern that a select with the given compare as its | |||
635 | /// predicate and given values as its true/false operands would match. | |||
636 | SelectPatternResult matchDecomposedSelectPattern( | |||
637 | CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS, | |||
638 | Instruction::CastOps *CastOp = nullptr, unsigned Depth = 0); | |||
639 | ||||
640 | /// Return the canonical comparison predicate for the specified | |||
641 | /// minimum/maximum flavor. | |||
642 | CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, | |||
643 | bool Ordered = false); | |||
644 | ||||
645 | /// Return the inverse minimum/maximum flavor of the specified flavor. | |||
646 | /// For example, signed minimum is the inverse of signed maximum. | |||
647 | SelectPatternFlavor getInverseMinMaxFlavor(SelectPatternFlavor SPF); | |||
648 | ||||
649 | /// Return the canonical inverse comparison predicate for the specified | |||
650 | /// minimum/maximum flavor. | |||
651 | CmpInst::Predicate getInverseMinMaxPred(SelectPatternFlavor SPF); | |||
652 | ||||
653 | /// Return true if RHS is known to be implied true by LHS. Return false if | |||
654 | /// RHS is known to be implied false by LHS. Otherwise, return None if no | |||
655 | /// implication can be made. | |||
656 | /// A & B must be i1 (boolean) values or a vector of such values. Note that | |||
657 | /// the truth table for implication is the same as <=u on i1 values (but not | |||
658 | /// <=s!). The truth table for both is: | |||
659 | /// | T | F (B) | |||
660 | /// T | T | F | |||
661 | /// F | T | T | |||
662 | /// (A) | |||
663 | Optional<bool> isImpliedCondition(const Value *LHS, const Value *RHS, | |||
664 | const DataLayout &DL, bool LHSIsTrue = true, | |||
665 | unsigned Depth = 0); | |||
666 | ||||
667 | /// Return the boolean condition value in the context of the given instruction | |||
668 | /// if it is known based on dominating conditions. | |||
669 | Optional<bool> isImpliedByDomCondition(const Value *Cond, | |||
670 | const Instruction *ContextI, | |||
671 | const DataLayout &DL); | |||
672 | ||||
673 | /// If Ptr1 is provably equal to Ptr2 plus a constant offset, return that | |||
674 | /// offset. For example, Ptr1 might be &A[42], and Ptr2 might be &A[40]. In | |||
675 | /// this case offset would be -8. | |||
676 | Optional<int64_t> isPointerOffset(const Value *Ptr1, const Value *Ptr2, | |||
677 | const DataLayout &DL); | |||
678 | } // end namespace llvm | |||
679 | ||||
680 | #endif // LLVM_ANALYSIS_VALUETRACKING_H |