| File: | llvm/lib/Analysis/ValueTracking.cpp |
| Warning: | line 1399, column 13 Value stored to 'L' is never read |
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| 1 | //===- ValueTracking.cpp - Walk computations to compute properties --------===// |
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // |
| 9 | // This file contains routines that help analyze properties that chains of |
| 10 | // computations have. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #include "llvm/Analysis/ValueTracking.h" |
| 15 | #include "llvm/ADT/APFloat.h" |
| 16 | #include "llvm/ADT/APInt.h" |
| 17 | #include "llvm/ADT/ArrayRef.h" |
| 18 | #include "llvm/ADT/None.h" |
| 19 | #include "llvm/ADT/Optional.h" |
| 20 | #include "llvm/ADT/STLExtras.h" |
| 21 | #include "llvm/ADT/SmallPtrSet.h" |
| 22 | #include "llvm/ADT/SmallSet.h" |
| 23 | #include "llvm/ADT/SmallVector.h" |
| 24 | #include "llvm/ADT/StringRef.h" |
| 25 | #include "llvm/ADT/iterator_range.h" |
| 26 | #include "llvm/Analysis/AliasAnalysis.h" |
| 27 | #include "llvm/Analysis/AssumeBundleQueries.h" |
| 28 | #include "llvm/Analysis/AssumptionCache.h" |
| 29 | #include "llvm/Analysis/GuardUtils.h" |
| 30 | #include "llvm/Analysis/InstructionSimplify.h" |
| 31 | #include "llvm/Analysis/Loads.h" |
| 32 | #include "llvm/Analysis/LoopInfo.h" |
| 33 | #include "llvm/Analysis/OptimizationRemarkEmitter.h" |
| 34 | #include "llvm/Analysis/TargetLibraryInfo.h" |
| 35 | #include "llvm/IR/Argument.h" |
| 36 | #include "llvm/IR/Attributes.h" |
| 37 | #include "llvm/IR/BasicBlock.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/IntrinsicsAArch64.h" |
| 55 | #include "llvm/IR/IntrinsicsX86.h" |
| 56 | #include "llvm/IR/LLVMContext.h" |
| 57 | #include "llvm/IR/Metadata.h" |
| 58 | #include "llvm/IR/Module.h" |
| 59 | #include "llvm/IR/Operator.h" |
| 60 | #include "llvm/IR/PatternMatch.h" |
| 61 | #include "llvm/IR/Type.h" |
| 62 | #include "llvm/IR/User.h" |
| 63 | #include "llvm/IR/Value.h" |
| 64 | #include "llvm/Support/Casting.h" |
| 65 | #include "llvm/Support/CommandLine.h" |
| 66 | #include "llvm/Support/Compiler.h" |
| 67 | #include "llvm/Support/ErrorHandling.h" |
| 68 | #include "llvm/Support/KnownBits.h" |
| 69 | #include "llvm/Support/MathExtras.h" |
| 70 | #include <algorithm> |
| 71 | #include <array> |
| 72 | #include <cassert> |
| 73 | #include <cstdint> |
| 74 | #include <iterator> |
| 75 | #include <utility> |
| 76 | |
| 77 | using namespace llvm; |
| 78 | using namespace llvm::PatternMatch; |
| 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.getPointerTypeSizeInBits(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 *, MaxAnalysisRecursionDepth> 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-13~++20210223111116+16ede0956cb1/llvm/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 const Instruction *safeCxtI(const Value *V1, const Value *V2, const Instruction *CxtI) { |
| 165 | // If we've been provided with a context instruction, then use that (provided |
| 166 | // it has been inserted). |
| 167 | if (CxtI && CxtI->getParent()) |
| 168 | return CxtI; |
| 169 | |
| 170 | // If the value is really an already-inserted instruction, then use that. |
| 171 | CxtI = dyn_cast<Instruction>(V1); |
| 172 | if (CxtI && CxtI->getParent()) |
| 173 | return CxtI; |
| 174 | |
| 175 | CxtI = dyn_cast<Instruction>(V2); |
| 176 | if (CxtI && CxtI->getParent()) |
| 177 | return CxtI; |
| 178 | |
| 179 | return nullptr; |
| 180 | } |
| 181 | |
| 182 | static bool getShuffleDemandedElts(const ShuffleVectorInst *Shuf, |
| 183 | const APInt &DemandedElts, |
| 184 | APInt &DemandedLHS, APInt &DemandedRHS) { |
| 185 | // The length of scalable vectors is unknown at compile time, thus we |
| 186 | // cannot check their values |
| 187 | if (isa<ScalableVectorType>(Shuf->getType())) |
| 188 | return false; |
| 189 | |
| 190 | int NumElts = |
| 191 | cast<FixedVectorType>(Shuf->getOperand(0)->getType())->getNumElements(); |
| 192 | int NumMaskElts = cast<FixedVectorType>(Shuf->getType())->getNumElements(); |
| 193 | DemandedLHS = DemandedRHS = APInt::getNullValue(NumElts); |
| 194 | if (DemandedElts.isNullValue()) |
| 195 | return true; |
| 196 | // Simple case of a shuffle with zeroinitializer. |
| 197 | if (all_of(Shuf->getShuffleMask(), [](int Elt) { return Elt == 0; })) { |
| 198 | DemandedLHS.setBit(0); |
| 199 | return true; |
| 200 | } |
| 201 | for (int i = 0; i != NumMaskElts; ++i) { |
| 202 | if (!DemandedElts[i]) |
| 203 | continue; |
| 204 | int M = Shuf->getMaskValue(i); |
| 205 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 205, __PRETTY_FUNCTION__)); |
| 206 | |
| 207 | // For undef elements, we don't know anything about the common state of |
| 208 | // the shuffle result. |
| 209 | if (M == -1) |
| 210 | return false; |
| 211 | if (M < NumElts) |
| 212 | DemandedLHS.setBit(M % NumElts); |
| 213 | else |
| 214 | DemandedRHS.setBit(M % NumElts); |
| 215 | } |
| 216 | |
| 217 | return true; |
| 218 | } |
| 219 | |
| 220 | static void computeKnownBits(const Value *V, const APInt &DemandedElts, |
| 221 | KnownBits &Known, unsigned Depth, const Query &Q); |
| 222 | |
| 223 | static void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth, |
| 224 | const Query &Q) { |
| 225 | // FIXME: We currently have no way to represent the DemandedElts of a scalable |
| 226 | // vector |
| 227 | if (isa<ScalableVectorType>(V->getType())) { |
| 228 | Known.resetAll(); |
| 229 | return; |
| 230 | } |
| 231 | |
| 232 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); |
| 233 | APInt DemandedElts = |
| 234 | FVTy ? APInt::getAllOnesValue(FVTy->getNumElements()) : APInt(1, 1); |
| 235 | computeKnownBits(V, DemandedElts, Known, Depth, Q); |
| 236 | } |
| 237 | |
| 238 | void llvm::computeKnownBits(const Value *V, KnownBits &Known, |
| 239 | const DataLayout &DL, unsigned Depth, |
| 240 | AssumptionCache *AC, const Instruction *CxtI, |
| 241 | const DominatorTree *DT, |
| 242 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { |
| 243 | ::computeKnownBits(V, Known, Depth, |
| 244 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); |
| 245 | } |
| 246 | |
| 247 | void llvm::computeKnownBits(const Value *V, const APInt &DemandedElts, |
| 248 | KnownBits &Known, const DataLayout &DL, |
| 249 | unsigned Depth, AssumptionCache *AC, |
| 250 | const Instruction *CxtI, const DominatorTree *DT, |
| 251 | OptimizationRemarkEmitter *ORE, bool UseInstrInfo) { |
| 252 | ::computeKnownBits(V, DemandedElts, Known, Depth, |
| 253 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); |
| 254 | } |
| 255 | |
| 256 | static KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts, |
| 257 | unsigned Depth, const Query &Q); |
| 258 | |
| 259 | static KnownBits computeKnownBits(const Value *V, unsigned Depth, |
| 260 | const Query &Q); |
| 261 | |
| 262 | KnownBits llvm::computeKnownBits(const Value *V, const DataLayout &DL, |
| 263 | unsigned Depth, AssumptionCache *AC, |
| 264 | const Instruction *CxtI, |
| 265 | const DominatorTree *DT, |
| 266 | OptimizationRemarkEmitter *ORE, |
| 267 | bool UseInstrInfo) { |
| 268 | return ::computeKnownBits( |
| 269 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); |
| 270 | } |
| 271 | |
| 272 | KnownBits llvm::computeKnownBits(const Value *V, const APInt &DemandedElts, |
| 273 | const DataLayout &DL, unsigned Depth, |
| 274 | AssumptionCache *AC, const Instruction *CxtI, |
| 275 | const DominatorTree *DT, |
| 276 | OptimizationRemarkEmitter *ORE, |
| 277 | bool UseInstrInfo) { |
| 278 | return ::computeKnownBits( |
| 279 | V, DemandedElts, Depth, |
| 280 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE)); |
| 281 | } |
| 282 | |
| 283 | bool llvm::haveNoCommonBitsSet(const Value *LHS, const Value *RHS, |
| 284 | const DataLayout &DL, AssumptionCache *AC, |
| 285 | const Instruction *CxtI, const DominatorTree *DT, |
| 286 | bool UseInstrInfo) { |
| 287 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 288, __PRETTY_FUNCTION__)) |
| 288 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 288, __PRETTY_FUNCTION__)); |
| 289 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 290, __PRETTY_FUNCTION__)) |
| 290 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 290, __PRETTY_FUNCTION__)); |
| 291 | // Look for an inverted mask: (X & ~M) op (Y & M). |
| 292 | Value *M; |
| 293 | if (match(LHS, m_c_And(m_Not(m_Value(M)), m_Value())) && |
| 294 | match(RHS, m_c_And(m_Specific(M), m_Value()))) |
| 295 | return true; |
| 296 | if (match(RHS, m_c_And(m_Not(m_Value(M)), m_Value())) && |
| 297 | match(LHS, m_c_And(m_Specific(M), m_Value()))) |
| 298 | return true; |
| 299 | IntegerType *IT = cast<IntegerType>(LHS->getType()->getScalarType()); |
| 300 | KnownBits LHSKnown(IT->getBitWidth()); |
| 301 | KnownBits RHSKnown(IT->getBitWidth()); |
| 302 | computeKnownBits(LHS, LHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); |
| 303 | computeKnownBits(RHS, RHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo); |
| 304 | return (LHSKnown.Zero | RHSKnown.Zero).isAllOnesValue(); |
| 305 | } |
| 306 | |
| 307 | bool llvm::isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI) { |
| 308 | for (const User *U : CxtI->users()) { |
| 309 | if (const ICmpInst *IC = dyn_cast<ICmpInst>(U)) |
| 310 | if (IC->isEquality()) |
| 311 | if (Constant *C = dyn_cast<Constant>(IC->getOperand(1))) |
| 312 | if (C->isNullValue()) |
| 313 | continue; |
| 314 | return false; |
| 315 | } |
| 316 | return true; |
| 317 | } |
| 318 | |
| 319 | static bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, |
| 320 | const Query &Q); |
| 321 | |
| 322 | bool llvm::isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL, |
| 323 | bool OrZero, unsigned Depth, |
| 324 | AssumptionCache *AC, const Instruction *CxtI, |
| 325 | const DominatorTree *DT, bool UseInstrInfo) { |
| 326 | return ::isKnownToBeAPowerOfTwo( |
| 327 | V, OrZero, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); |
| 328 | } |
| 329 | |
| 330 | static bool isKnownNonZero(const Value *V, const APInt &DemandedElts, |
| 331 | unsigned Depth, const Query &Q); |
| 332 | |
| 333 | static bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q); |
| 334 | |
| 335 | bool llvm::isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth, |
| 336 | AssumptionCache *AC, const Instruction *CxtI, |
| 337 | const DominatorTree *DT, bool UseInstrInfo) { |
| 338 | return ::isKnownNonZero(V, Depth, |
| 339 | Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); |
| 340 | } |
| 341 | |
| 342 | bool llvm::isKnownNonNegative(const Value *V, const DataLayout &DL, |
| 343 | unsigned Depth, AssumptionCache *AC, |
| 344 | const Instruction *CxtI, const DominatorTree *DT, |
| 345 | bool UseInstrInfo) { |
| 346 | KnownBits Known = |
| 347 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); |
| 348 | return Known.isNonNegative(); |
| 349 | } |
| 350 | |
| 351 | bool llvm::isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth, |
| 352 | AssumptionCache *AC, const Instruction *CxtI, |
| 353 | const DominatorTree *DT, bool UseInstrInfo) { |
| 354 | if (auto *CI = dyn_cast<ConstantInt>(V)) |
| 355 | return CI->getValue().isStrictlyPositive(); |
| 356 | |
| 357 | // TODO: We'd doing two recursive queries here. We should factor this such |
| 358 | // that only a single query is needed. |
| 359 | return isKnownNonNegative(V, DL, Depth, AC, CxtI, DT, UseInstrInfo) && |
| 360 | isKnownNonZero(V, DL, Depth, AC, CxtI, DT, UseInstrInfo); |
| 361 | } |
| 362 | |
| 363 | bool llvm::isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth, |
| 364 | AssumptionCache *AC, const Instruction *CxtI, |
| 365 | const DominatorTree *DT, bool UseInstrInfo) { |
| 366 | KnownBits Known = |
| 367 | computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo); |
| 368 | return Known.isNegative(); |
| 369 | } |
| 370 | |
| 371 | static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth, |
| 372 | const Query &Q); |
| 373 | |
| 374 | bool llvm::isKnownNonEqual(const Value *V1, const Value *V2, |
| 375 | const DataLayout &DL, AssumptionCache *AC, |
| 376 | const Instruction *CxtI, const DominatorTree *DT, |
| 377 | bool UseInstrInfo) { |
| 378 | return ::isKnownNonEqual(V1, V2, 0, |
| 379 | Query(DL, AC, safeCxtI(V2, V1, CxtI), DT, |
| 380 | UseInstrInfo, /*ORE=*/nullptr)); |
| 381 | } |
| 382 | |
| 383 | static bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, |
| 384 | const Query &Q); |
| 385 | |
| 386 | bool llvm::MaskedValueIsZero(const Value *V, const APInt &Mask, |
| 387 | const DataLayout &DL, unsigned Depth, |
| 388 | AssumptionCache *AC, const Instruction *CxtI, |
| 389 | const DominatorTree *DT, bool UseInstrInfo) { |
| 390 | return ::MaskedValueIsZero( |
| 391 | V, Mask, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); |
| 392 | } |
| 393 | |
| 394 | static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts, |
| 395 | unsigned Depth, const Query &Q); |
| 396 | |
| 397 | static unsigned ComputeNumSignBits(const Value *V, unsigned Depth, |
| 398 | const Query &Q) { |
| 399 | // FIXME: We currently have no way to represent the DemandedElts of a scalable |
| 400 | // vector |
| 401 | if (isa<ScalableVectorType>(V->getType())) |
| 402 | return 1; |
| 403 | |
| 404 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); |
| 405 | APInt DemandedElts = |
| 406 | FVTy ? APInt::getAllOnesValue(FVTy->getNumElements()) : APInt(1, 1); |
| 407 | return ComputeNumSignBits(V, DemandedElts, Depth, Q); |
| 408 | } |
| 409 | |
| 410 | unsigned llvm::ComputeNumSignBits(const Value *V, const DataLayout &DL, |
| 411 | unsigned Depth, AssumptionCache *AC, |
| 412 | const Instruction *CxtI, |
| 413 | const DominatorTree *DT, bool UseInstrInfo) { |
| 414 | return ::ComputeNumSignBits( |
| 415 | V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo)); |
| 416 | } |
| 417 | |
| 418 | static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1, |
| 419 | bool NSW, const APInt &DemandedElts, |
| 420 | KnownBits &KnownOut, KnownBits &Known2, |
| 421 | unsigned Depth, const Query &Q) { |
| 422 | computeKnownBits(Op1, DemandedElts, KnownOut, Depth + 1, Q); |
| 423 | |
| 424 | // If one operand is unknown and we have no nowrap information, |
| 425 | // the result will be unknown independently of the second operand. |
| 426 | if (KnownOut.isUnknown() && !NSW) |
| 427 | return; |
| 428 | |
| 429 | computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q); |
| 430 | KnownOut = KnownBits::computeForAddSub(Add, NSW, Known2, KnownOut); |
| 431 | } |
| 432 | |
| 433 | static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW, |
| 434 | const APInt &DemandedElts, KnownBits &Known, |
| 435 | KnownBits &Known2, unsigned Depth, |
| 436 | const Query &Q) { |
| 437 | computeKnownBits(Op1, DemandedElts, Known, Depth + 1, Q); |
| 438 | computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q); |
| 439 | |
| 440 | bool isKnownNegative = false; |
| 441 | bool isKnownNonNegative = false; |
| 442 | // If the multiplication is known not to overflow, compute the sign bit. |
| 443 | if (NSW) { |
| 444 | if (Op0 == Op1) { |
| 445 | // The product of a number with itself is non-negative. |
| 446 | isKnownNonNegative = true; |
| 447 | } else { |
| 448 | bool isKnownNonNegativeOp1 = Known.isNonNegative(); |
| 449 | bool isKnownNonNegativeOp0 = Known2.isNonNegative(); |
| 450 | bool isKnownNegativeOp1 = Known.isNegative(); |
| 451 | bool isKnownNegativeOp0 = Known2.isNegative(); |
| 452 | // The product of two numbers with the same sign is non-negative. |
| 453 | isKnownNonNegative = (isKnownNegativeOp1 && isKnownNegativeOp0) || |
| 454 | (isKnownNonNegativeOp1 && isKnownNonNegativeOp0); |
| 455 | // The product of a negative number and a non-negative number is either |
| 456 | // negative or zero. |
| 457 | if (!isKnownNonNegative) |
| 458 | isKnownNegative = |
| 459 | (isKnownNegativeOp1 && isKnownNonNegativeOp0 && |
| 460 | Known2.isNonZero()) || |
| 461 | (isKnownNegativeOp0 && isKnownNonNegativeOp1 && Known.isNonZero()); |
| 462 | } |
| 463 | } |
| 464 | |
| 465 | Known = KnownBits::computeForMul(Known, Known2); |
| 466 | |
| 467 | // Only make use of no-wrap flags if we failed to compute the sign bit |
| 468 | // directly. This matters if the multiplication always overflows, in |
| 469 | // which case we prefer to follow the result of the direct computation, |
| 470 | // though as the program is invoking undefined behaviour we can choose |
| 471 | // whatever we like here. |
| 472 | if (isKnownNonNegative && !Known.isNegative()) |
| 473 | Known.makeNonNegative(); |
| 474 | else if (isKnownNegative && !Known.isNonNegative()) |
| 475 | Known.makeNegative(); |
| 476 | } |
| 477 | |
| 478 | void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges, |
| 479 | KnownBits &Known) { |
| 480 | unsigned BitWidth = Known.getBitWidth(); |
| 481 | unsigned NumRanges = Ranges.getNumOperands() / 2; |
| 482 | assert(NumRanges >= 1)((NumRanges >= 1) ? static_cast<void> (0) : __assert_fail ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 482, __PRETTY_FUNCTION__)); |
| 483 | |
| 484 | Known.Zero.setAllBits(); |
| 485 | Known.One.setAllBits(); |
| 486 | |
| 487 | for (unsigned i = 0; i < NumRanges; ++i) { |
| 488 | ConstantInt *Lower = |
| 489 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 0)); |
| 490 | ConstantInt *Upper = |
| 491 | mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1)); |
| 492 | ConstantRange Range(Lower->getValue(), Upper->getValue()); |
| 493 | |
| 494 | // The first CommonPrefixBits of all values in Range are equal. |
| 495 | unsigned CommonPrefixBits = |
| 496 | (Range.getUnsignedMax() ^ Range.getUnsignedMin()).countLeadingZeros(); |
| 497 | APInt Mask = APInt::getHighBitsSet(BitWidth, CommonPrefixBits); |
| 498 | APInt UnsignedMax = Range.getUnsignedMax().zextOrTrunc(BitWidth); |
| 499 | Known.One &= UnsignedMax & Mask; |
| 500 | Known.Zero &= ~UnsignedMax & Mask; |
| 501 | } |
| 502 | } |
| 503 | |
| 504 | static bool isEphemeralValueOf(const Instruction *I, const Value *E) { |
| 505 | SmallVector<const Value *, 16> WorkSet(1, I); |
| 506 | SmallPtrSet<const Value *, 32> Visited; |
| 507 | SmallPtrSet<const Value *, 16> EphValues; |
| 508 | |
| 509 | // The instruction defining an assumption's condition itself is always |
| 510 | // considered ephemeral to that assumption (even if it has other |
| 511 | // non-ephemeral users). See r246696's test case for an example. |
| 512 | if (is_contained(I->operands(), E)) |
| 513 | return true; |
| 514 | |
| 515 | while (!WorkSet.empty()) { |
| 516 | const Value *V = WorkSet.pop_back_val(); |
| 517 | if (!Visited.insert(V).second) |
| 518 | continue; |
| 519 | |
| 520 | // If all uses of this value are ephemeral, then so is this value. |
| 521 | if (llvm::all_of(V->users(), [&](const User *U) { |
| 522 | return EphValues.count(U); |
| 523 | })) { |
| 524 | if (V == E) |
| 525 | return true; |
| 526 | |
| 527 | if (V == I || isSafeToSpeculativelyExecute(V)) { |
| 528 | EphValues.insert(V); |
| 529 | if (const User *U = dyn_cast<User>(V)) |
| 530 | append_range(WorkSet, U->operands()); |
| 531 | } |
| 532 | } |
| 533 | } |
| 534 | |
| 535 | return false; |
| 536 | } |
| 537 | |
| 538 | // Is this an intrinsic that cannot be speculated but also cannot trap? |
| 539 | bool llvm::isAssumeLikeIntrinsic(const Instruction *I) { |
| 540 | if (const IntrinsicInst *CI = dyn_cast<IntrinsicInst>(I)) |
| 541 | return CI->isAssumeLikeIntrinsic(); |
| 542 | |
| 543 | return false; |
| 544 | } |
| 545 | |
| 546 | bool llvm::isValidAssumeForContext(const Instruction *Inv, |
| 547 | const Instruction *CxtI, |
| 548 | const DominatorTree *DT) { |
| 549 | // There are two restrictions on the use of an assume: |
| 550 | // 1. The assume must dominate the context (or the control flow must |
| 551 | // reach the assume whenever it reaches the context). |
| 552 | // 2. The context must not be in the assume's set of ephemeral values |
| 553 | // (otherwise we will use the assume to prove that the condition |
| 554 | // feeding the assume is trivially true, thus causing the removal of |
| 555 | // the assume). |
| 556 | |
| 557 | if (Inv->getParent() == CxtI->getParent()) { |
| 558 | // If Inv and CtxI are in the same block, check if the assume (Inv) is first |
| 559 | // in the BB. |
| 560 | if (Inv->comesBefore(CxtI)) |
| 561 | return true; |
| 562 | |
| 563 | // Don't let an assume affect itself - this would cause the problems |
| 564 | // `isEphemeralValueOf` is trying to prevent, and it would also make |
| 565 | // the loop below go out of bounds. |
| 566 | if (Inv == CxtI) |
| 567 | return false; |
| 568 | |
| 569 | // The context comes first, but they're both in the same block. |
| 570 | // Make sure there is nothing in between that might interrupt |
| 571 | // the control flow, not even CxtI itself. |
| 572 | // We limit the scan distance between the assume and its context instruction |
| 573 | // to avoid a compile-time explosion. This limit is chosen arbitrarily, so |
| 574 | // it can be adjusted if needed (could be turned into a cl::opt). |
| 575 | unsigned ScanLimit = 15; |
| 576 | for (BasicBlock::const_iterator I(CxtI), IE(Inv); I != IE; ++I) |
| 577 | if (!isGuaranteedToTransferExecutionToSuccessor(&*I) || --ScanLimit == 0) |
| 578 | return false; |
| 579 | |
| 580 | return !isEphemeralValueOf(Inv, CxtI); |
| 581 | } |
| 582 | |
| 583 | // Inv and CxtI are in different blocks. |
| 584 | if (DT) { |
| 585 | if (DT->dominates(Inv, CxtI)) |
| 586 | return true; |
| 587 | } else if (Inv->getParent() == CxtI->getParent()->getSinglePredecessor()) { |
| 588 | // We don't have a DT, but this trivially dominates. |
| 589 | return true; |
| 590 | } |
| 591 | |
| 592 | return false; |
| 593 | } |
| 594 | |
| 595 | static bool cmpExcludesZero(CmpInst::Predicate Pred, const Value *RHS) { |
| 596 | // v u> y implies v != 0. |
| 597 | if (Pred == ICmpInst::ICMP_UGT) |
| 598 | return true; |
| 599 | |
| 600 | // Special-case v != 0 to also handle v != null. |
| 601 | if (Pred == ICmpInst::ICMP_NE) |
| 602 | return match(RHS, m_Zero()); |
| 603 | |
| 604 | // All other predicates - rely on generic ConstantRange handling. |
| 605 | const APInt *C; |
| 606 | if (!match(RHS, m_APInt(C))) |
| 607 | return false; |
| 608 | |
| 609 | ConstantRange TrueValues = ConstantRange::makeExactICmpRegion(Pred, *C); |
| 610 | return !TrueValues.contains(APInt::getNullValue(C->getBitWidth())); |
| 611 | } |
| 612 | |
| 613 | static bool isKnownNonZeroFromAssume(const Value *V, const Query &Q) { |
| 614 | // Use of assumptions is context-sensitive. If we don't have a context, we |
| 615 | // cannot use them! |
| 616 | if (!Q.AC || !Q.CxtI) |
| 617 | return false; |
| 618 | |
| 619 | if (Q.CxtI && V->getType()->isPointerTy()) { |
| 620 | SmallVector<Attribute::AttrKind, 2> AttrKinds{Attribute::NonNull}; |
| 621 | if (!NullPointerIsDefined(Q.CxtI->getFunction(), |
| 622 | V->getType()->getPointerAddressSpace())) |
| 623 | AttrKinds.push_back(Attribute::Dereferenceable); |
| 624 | |
| 625 | if (getKnowledgeValidInContext(V, AttrKinds, Q.CxtI, Q.DT, Q.AC)) |
| 626 | return true; |
| 627 | } |
| 628 | |
| 629 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { |
| 630 | if (!AssumeVH) |
| 631 | continue; |
| 632 | CallInst *I = cast<CallInst>(AssumeVH); |
| 633 | assert(I->getFunction() == Q.CxtI->getFunction() &&((I->getFunction() == Q.CxtI->getFunction() && "Got assumption for the wrong function!" ) ? static_cast<void> (0) : __assert_fail ("I->getFunction() == Q.CxtI->getFunction() && \"Got assumption for the wrong function!\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 634, __PRETTY_FUNCTION__)) |
| 634 | "Got assumption for the wrong function!")((I->getFunction() == Q.CxtI->getFunction() && "Got assumption for the wrong function!" ) ? static_cast<void> (0) : __assert_fail ("I->getFunction() == Q.CxtI->getFunction() && \"Got assumption for the wrong function!\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 634, __PRETTY_FUNCTION__)); |
| 635 | if (Q.isExcluded(I)) |
| 636 | continue; |
| 637 | |
| 638 | // Warning: This loop can end up being somewhat performance sensitive. |
| 639 | // We're running this loop for once for each value queried resulting in a |
| 640 | // runtime of ~O(#assumes * #values). |
| 641 | |
| 642 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 643, __PRETTY_FUNCTION__)) |
| 643 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 643, __PRETTY_FUNCTION__)); |
| 644 | |
| 645 | Value *RHS; |
| 646 | CmpInst::Predicate Pred; |
| 647 | auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V))); |
| 648 | if (!match(I->getArgOperand(0), m_c_ICmp(Pred, m_V, m_Value(RHS)))) |
| 649 | return false; |
| 650 | |
| 651 | if (cmpExcludesZero(Pred, RHS) && isValidAssumeForContext(I, Q.CxtI, Q.DT)) |
| 652 | return true; |
| 653 | } |
| 654 | |
| 655 | return false; |
| 656 | } |
| 657 | |
| 658 | static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known, |
| 659 | unsigned Depth, const Query &Q) { |
| 660 | // Use of assumptions is context-sensitive. If we don't have a context, we |
| 661 | // cannot use them! |
| 662 | if (!Q.AC || !Q.CxtI) |
| 663 | return; |
| 664 | |
| 665 | unsigned BitWidth = Known.getBitWidth(); |
| 666 | |
| 667 | // Refine Known set if the pointer alignment is set by assume bundles. |
| 668 | if (V->getType()->isPointerTy()) { |
| 669 | if (RetainedKnowledge RK = getKnowledgeValidInContext( |
| 670 | V, {Attribute::Alignment}, Q.CxtI, Q.DT, Q.AC)) { |
| 671 | Known.Zero.setLowBits(Log2_32(RK.ArgValue)); |
| 672 | } |
| 673 | } |
| 674 | |
| 675 | // Note that the patterns below need to be kept in sync with the code |
| 676 | // in AssumptionCache::updateAffectedValues. |
| 677 | |
| 678 | for (auto &AssumeVH : Q.AC->assumptionsFor(V)) { |
| 679 | if (!AssumeVH) |
| 680 | continue; |
| 681 | CallInst *I = cast<CallInst>(AssumeVH); |
| 682 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 683, __PRETTY_FUNCTION__)) |
| 683 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 683, __PRETTY_FUNCTION__)); |
| 684 | if (Q.isExcluded(I)) |
| 685 | continue; |
| 686 | |
| 687 | // Warning: This loop can end up being somewhat performance sensitive. |
| 688 | // We're running this loop for once for each value queried resulting in a |
| 689 | // runtime of ~O(#assumes * #values). |
| 690 | |
| 691 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 692, __PRETTY_FUNCTION__)) |
| 692 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 692, __PRETTY_FUNCTION__)); |
| 693 | |
| 694 | Value *Arg = I->getArgOperand(0); |
| 695 | |
| 696 | if (Arg == V && isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 697 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 697, __PRETTY_FUNCTION__)); |
| 698 | Known.setAllOnes(); |
| 699 | return; |
| 700 | } |
| 701 | if (match(Arg, m_Not(m_Specific(V))) && |
| 702 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 703 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 703, __PRETTY_FUNCTION__)); |
| 704 | Known.setAllZero(); |
| 705 | return; |
| 706 | } |
| 707 | |
| 708 | // The remaining tests are all recursive, so bail out if we hit the limit. |
| 709 | if (Depth == MaxAnalysisRecursionDepth) |
| 710 | continue; |
| 711 | |
| 712 | ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg); |
| 713 | if (!Cmp) |
| 714 | continue; |
| 715 | |
| 716 | // Note that ptrtoint may change the bitwidth. |
| 717 | Value *A, *B; |
| 718 | auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V))); |
| 719 | |
| 720 | CmpInst::Predicate Pred; |
| 721 | uint64_t C; |
| 722 | switch (Cmp->getPredicate()) { |
| 723 | default: |
| 724 | break; |
| 725 | case ICmpInst::ICMP_EQ: |
| 726 | // assume(v = a) |
| 727 | if (match(Cmp, m_c_ICmp(Pred, m_V, m_Value(A))) && |
| 728 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 729 | KnownBits RHSKnown = |
| 730 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 731 | Known.Zero |= RHSKnown.Zero; |
| 732 | Known.One |= RHSKnown.One; |
| 733 | // assume(v & b = a) |
| 734 | } else if (match(Cmp, |
| 735 | m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)), m_Value(A))) && |
| 736 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 737 | KnownBits RHSKnown = |
| 738 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 739 | KnownBits MaskKnown = |
| 740 | computeKnownBits(B, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 741 | |
| 742 | // For those bits in the mask that are known to be one, we can propagate |
| 743 | // known bits from the RHS to V. |
| 744 | Known.Zero |= RHSKnown.Zero & MaskKnown.One; |
| 745 | Known.One |= RHSKnown.One & MaskKnown.One; |
| 746 | // assume(~(v & b) = a) |
| 747 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))), |
| 748 | m_Value(A))) && |
| 749 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 750 | KnownBits RHSKnown = |
| 751 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 752 | KnownBits MaskKnown = |
| 753 | computeKnownBits(B, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 754 | |
| 755 | // For those bits in the mask that are known to be one, we can propagate |
| 756 | // inverted known bits from the RHS to V. |
| 757 | Known.Zero |= RHSKnown.One & MaskKnown.One; |
| 758 | Known.One |= RHSKnown.Zero & MaskKnown.One; |
| 759 | // assume(v | b = a) |
| 760 | } else if (match(Cmp, |
| 761 | m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), m_Value(A))) && |
| 762 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 763 | KnownBits RHSKnown = |
| 764 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 765 | KnownBits BKnown = |
| 766 | computeKnownBits(B, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 767 | |
| 768 | // For those bits in B that are known to be zero, we can propagate known |
| 769 | // bits from the RHS to V. |
| 770 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; |
| 771 | Known.One |= RHSKnown.One & BKnown.Zero; |
| 772 | // assume(~(v | b) = a) |
| 773 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))), |
| 774 | m_Value(A))) && |
| 775 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 776 | KnownBits RHSKnown = |
| 777 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 778 | KnownBits BKnown = |
| 779 | computeKnownBits(B, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 780 | |
| 781 | // For those bits in B that are known to be zero, we can propagate |
| 782 | // inverted known bits from the RHS to V. |
| 783 | Known.Zero |= RHSKnown.One & BKnown.Zero; |
| 784 | Known.One |= RHSKnown.Zero & BKnown.Zero; |
| 785 | // assume(v ^ b = a) |
| 786 | } else if (match(Cmp, |
| 787 | m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), m_Value(A))) && |
| 788 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 789 | KnownBits RHSKnown = |
| 790 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 791 | KnownBits BKnown = |
| 792 | computeKnownBits(B, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 793 | |
| 794 | // For those bits in B that are known to be zero, we can propagate known |
| 795 | // bits from the RHS to V. For those bits in B that are known to be one, |
| 796 | // we can propagate inverted known bits from the RHS to V. |
| 797 | Known.Zero |= RHSKnown.Zero & BKnown.Zero; |
| 798 | Known.One |= RHSKnown.One & BKnown.Zero; |
| 799 | Known.Zero |= RHSKnown.One & BKnown.One; |
| 800 | Known.One |= RHSKnown.Zero & BKnown.One; |
| 801 | // assume(~(v ^ b) = a) |
| 802 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))), |
| 803 | m_Value(A))) && |
| 804 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 805 | KnownBits RHSKnown = |
| 806 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 807 | KnownBits BKnown = |
| 808 | computeKnownBits(B, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 809 | |
| 810 | // For those bits in B that are known to be zero, we can propagate |
| 811 | // inverted known bits from the RHS to V. For those bits in B that are |
| 812 | // known to be one, we can propagate known bits from the RHS to V. |
| 813 | Known.Zero |= RHSKnown.One & BKnown.Zero; |
| 814 | Known.One |= RHSKnown.Zero & BKnown.Zero; |
| 815 | Known.Zero |= RHSKnown.Zero & BKnown.One; |
| 816 | Known.One |= RHSKnown.One & BKnown.One; |
| 817 | // assume(v << c = a) |
| 818 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)), |
| 819 | m_Value(A))) && |
| 820 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { |
| 821 | KnownBits RHSKnown = |
| 822 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 823 | |
| 824 | // For those bits in RHS that are known, we can propagate them to known |
| 825 | // bits in V shifted to the right by C. |
| 826 | RHSKnown.Zero.lshrInPlace(C); |
| 827 | Known.Zero |= RHSKnown.Zero; |
| 828 | RHSKnown.One.lshrInPlace(C); |
| 829 | Known.One |= RHSKnown.One; |
| 830 | // assume(~(v << c) = a) |
| 831 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))), |
| 832 | m_Value(A))) && |
| 833 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { |
| 834 | KnownBits RHSKnown = |
| 835 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 836 | // For those bits in RHS that are known, we can propagate them inverted |
| 837 | // to known bits in V shifted to the right by C. |
| 838 | RHSKnown.One.lshrInPlace(C); |
| 839 | Known.Zero |= RHSKnown.One; |
| 840 | RHSKnown.Zero.lshrInPlace(C); |
| 841 | Known.One |= RHSKnown.Zero; |
| 842 | // assume(v >> c = a) |
| 843 | } else if (match(Cmp, m_c_ICmp(Pred, m_Shr(m_V, m_ConstantInt(C)), |
| 844 | m_Value(A))) && |
| 845 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { |
| 846 | KnownBits RHSKnown = |
| 847 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 848 | // For those bits in RHS that are known, we can propagate them to known |
| 849 | // bits in V shifted to the right by C. |
| 850 | Known.Zero |= RHSKnown.Zero << C; |
| 851 | Known.One |= RHSKnown.One << C; |
| 852 | // assume(~(v >> c) = a) |
| 853 | } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shr(m_V, m_ConstantInt(C))), |
| 854 | m_Value(A))) && |
| 855 | isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) { |
| 856 | KnownBits RHSKnown = |
| 857 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 858 | // For those bits in RHS that are known, we can propagate them inverted |
| 859 | // to known bits in V shifted to the right by C. |
| 860 | Known.Zero |= RHSKnown.One << C; |
| 861 | Known.One |= RHSKnown.Zero << C; |
| 862 | } |
| 863 | break; |
| 864 | case ICmpInst::ICMP_SGE: |
| 865 | // assume(v >=_s c) where c is non-negative |
| 866 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && |
| 867 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 868 | KnownBits RHSKnown = |
| 869 | computeKnownBits(A, Depth + 1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 870 | |
| 871 | if (RHSKnown.isNonNegative()) { |
| 872 | // We know that the sign bit is zero. |
| 873 | Known.makeNonNegative(); |
| 874 | } |
| 875 | } |
| 876 | break; |
| 877 | case ICmpInst::ICMP_SGT: |
| 878 | // assume(v >_s c) where c is at least -1. |
| 879 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && |
| 880 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 881 | KnownBits RHSKnown = |
| 882 | computeKnownBits(A, Depth + 1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 883 | |
| 884 | if (RHSKnown.isAllOnes() || RHSKnown.isNonNegative()) { |
| 885 | // We know that the sign bit is zero. |
| 886 | Known.makeNonNegative(); |
| 887 | } |
| 888 | } |
| 889 | break; |
| 890 | case ICmpInst::ICMP_SLE: |
| 891 | // assume(v <=_s c) where c is negative |
| 892 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && |
| 893 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 894 | KnownBits RHSKnown = |
| 895 | computeKnownBits(A, Depth + 1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 896 | |
| 897 | if (RHSKnown.isNegative()) { |
| 898 | // We know that the sign bit is one. |
| 899 | Known.makeNegative(); |
| 900 | } |
| 901 | } |
| 902 | break; |
| 903 | case ICmpInst::ICMP_SLT: |
| 904 | // assume(v <_s c) where c is non-positive |
| 905 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && |
| 906 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 907 | KnownBits RHSKnown = |
| 908 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 909 | |
| 910 | if (RHSKnown.isZero() || RHSKnown.isNegative()) { |
| 911 | // We know that the sign bit is one. |
| 912 | Known.makeNegative(); |
| 913 | } |
| 914 | } |
| 915 | break; |
| 916 | case ICmpInst::ICMP_ULE: |
| 917 | // assume(v <=_u c) |
| 918 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && |
| 919 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 920 | KnownBits RHSKnown = |
| 921 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 922 | |
| 923 | // Whatever high bits in c are zero are known to be zero. |
| 924 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); |
| 925 | } |
| 926 | break; |
| 927 | case ICmpInst::ICMP_ULT: |
| 928 | // assume(v <_u c) |
| 929 | if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) && |
| 930 | isValidAssumeForContext(I, Q.CxtI, Q.DT)) { |
| 931 | KnownBits RHSKnown = |
| 932 | computeKnownBits(A, Depth+1, Query(Q, I)).anyextOrTrunc(BitWidth); |
| 933 | |
| 934 | // If the RHS is known zero, then this assumption must be wrong (nothing |
| 935 | // is unsigned less than zero). Signal a conflict and get out of here. |
| 936 | if (RHSKnown.isZero()) { |
| 937 | Known.Zero.setAllBits(); |
| 938 | Known.One.setAllBits(); |
| 939 | break; |
| 940 | } |
| 941 | |
| 942 | // Whatever high bits in c are zero are known to be zero (if c is a power |
| 943 | // of 2, then one more). |
| 944 | if (isKnownToBeAPowerOfTwo(A, false, Depth + 1, Query(Q, I))) |
| 945 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros() + 1); |
| 946 | else |
| 947 | Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros()); |
| 948 | } |
| 949 | break; |
| 950 | } |
| 951 | } |
| 952 | |
| 953 | // If assumptions conflict with each other or previous known bits, then we |
| 954 | // have a logical fallacy. It's possible that the assumption is not reachable, |
| 955 | // so this isn't a real bug. On the other hand, the program may have undefined |
| 956 | // behavior, or we might have a bug in the compiler. We can't assert/crash, so |
| 957 | // clear out the known bits, try to warn the user, and hope for the best. |
| 958 | if (Known.Zero.intersects(Known.One)) { |
| 959 | Known.resetAll(); |
| 960 | |
| 961 | if (Q.ORE) |
| 962 | Q.ORE->emit([&]() { |
| 963 | auto *CxtI = const_cast<Instruction *>(Q.CxtI); |
| 964 | return OptimizationRemarkAnalysis("value-tracking", "BadAssumption", |
| 965 | CxtI) |
| 966 | << "Detected conflicting code assumptions. Program may " |
| 967 | "have undefined behavior, or compiler may have " |
| 968 | "internal error."; |
| 969 | }); |
| 970 | } |
| 971 | } |
| 972 | |
| 973 | /// Compute known bits from a shift operator, including those with a |
| 974 | /// non-constant shift amount. Known is the output of this function. Known2 is a |
| 975 | /// pre-allocated temporary with the same bit width as Known and on return |
| 976 | /// contains the known bit of the shift value source. KF is an |
| 977 | /// operator-specific function that, given the known-bits and a shift amount, |
| 978 | /// compute the implied known-bits of the shift operator's result respectively |
| 979 | /// for that shift amount. The results from calling KF are conservatively |
| 980 | /// combined for all permitted shift amounts. |
| 981 | static void computeKnownBitsFromShiftOperator( |
| 982 | const Operator *I, const APInt &DemandedElts, KnownBits &Known, |
| 983 | KnownBits &Known2, unsigned Depth, const Query &Q, |
| 984 | function_ref<KnownBits(const KnownBits &, const KnownBits &)> KF) { |
| 985 | unsigned BitWidth = Known.getBitWidth(); |
| 986 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); |
| 987 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); |
| 988 | |
| 989 | // Note: We cannot use Known.Zero.getLimitedValue() here, because if |
| 990 | // BitWidth > 64 and any upper bits are known, we'll end up returning the |
| 991 | // limit value (which implies all bits are known). |
| 992 | uint64_t ShiftAmtKZ = Known.Zero.zextOrTrunc(64).getZExtValue(); |
| 993 | uint64_t ShiftAmtKO = Known.One.zextOrTrunc(64).getZExtValue(); |
| 994 | bool ShiftAmtIsConstant = Known.isConstant(); |
| 995 | bool MaxShiftAmtIsOutOfRange = Known.getMaxValue().uge(BitWidth); |
| 996 | |
| 997 | if (ShiftAmtIsConstant) { |
| 998 | Known = KF(Known2, Known); |
| 999 | |
| 1000 | // If the known bits conflict, this must be an overflowing left shift, so |
| 1001 | // the shift result is poison. We can return anything we want. Choose 0 for |
| 1002 | // the best folding opportunity. |
| 1003 | if (Known.hasConflict()) |
| 1004 | Known.setAllZero(); |
| 1005 | |
| 1006 | return; |
| 1007 | } |
| 1008 | |
| 1009 | // If the shift amount could be greater than or equal to the bit-width of the |
| 1010 | // LHS, the value could be poison, but bail out because the check below is |
| 1011 | // expensive. |
| 1012 | // TODO: Should we just carry on? |
| 1013 | if (MaxShiftAmtIsOutOfRange) { |
| 1014 | Known.resetAll(); |
| 1015 | return; |
| 1016 | } |
| 1017 | |
| 1018 | // It would be more-clearly correct to use the two temporaries for this |
| 1019 | // calculation. Reusing the APInts here to prevent unnecessary allocations. |
| 1020 | Known.resetAll(); |
| 1021 | |
| 1022 | // If we know the shifter operand is nonzero, we can sometimes infer more |
| 1023 | // known bits. However this is expensive to compute, so be lazy about it and |
| 1024 | // only compute it when absolutely necessary. |
| 1025 | Optional<bool> ShifterOperandIsNonZero; |
| 1026 | |
| 1027 | // Early exit if we can't constrain any well-defined shift amount. |
| 1028 | if (!(ShiftAmtKZ & (PowerOf2Ceil(BitWidth) - 1)) && |
| 1029 | !(ShiftAmtKO & (PowerOf2Ceil(BitWidth) - 1))) { |
| 1030 | ShifterOperandIsNonZero = |
| 1031 | isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q); |
| 1032 | if (!*ShifterOperandIsNonZero) |
| 1033 | return; |
| 1034 | } |
| 1035 | |
| 1036 | Known.Zero.setAllBits(); |
| 1037 | Known.One.setAllBits(); |
| 1038 | for (unsigned ShiftAmt = 0; ShiftAmt < BitWidth; ++ShiftAmt) { |
| 1039 | // Combine the shifted known input bits only for those shift amounts |
| 1040 | // compatible with its known constraints. |
| 1041 | if ((ShiftAmt & ~ShiftAmtKZ) != ShiftAmt) |
| 1042 | continue; |
| 1043 | if ((ShiftAmt | ShiftAmtKO) != ShiftAmt) |
| 1044 | continue; |
| 1045 | // If we know the shifter is nonzero, we may be able to infer more known |
| 1046 | // bits. This check is sunk down as far as possible to avoid the expensive |
| 1047 | // call to isKnownNonZero if the cheaper checks above fail. |
| 1048 | if (ShiftAmt == 0) { |
| 1049 | if (!ShifterOperandIsNonZero.hasValue()) |
| 1050 | ShifterOperandIsNonZero = |
| 1051 | isKnownNonZero(I->getOperand(1), DemandedElts, Depth + 1, Q); |
| 1052 | if (*ShifterOperandIsNonZero) |
| 1053 | continue; |
| 1054 | } |
| 1055 | |
| 1056 | Known = KnownBits::commonBits( |
| 1057 | Known, KF(Known2, KnownBits::makeConstant(APInt(32, ShiftAmt)))); |
| 1058 | } |
| 1059 | |
| 1060 | // If the known bits conflict, the result is poison. Return a 0 and hope the |
| 1061 | // caller can further optimize that. |
| 1062 | if (Known.hasConflict()) |
| 1063 | Known.setAllZero(); |
| 1064 | } |
| 1065 | |
| 1066 | static void computeKnownBitsFromOperator(const Operator *I, |
| 1067 | const APInt &DemandedElts, |
| 1068 | KnownBits &Known, unsigned Depth, |
| 1069 | const Query &Q) { |
| 1070 | unsigned BitWidth = Known.getBitWidth(); |
| 1071 | |
| 1072 | KnownBits Known2(BitWidth); |
| 1073 | switch (I->getOpcode()) { |
| 1074 | default: break; |
| 1075 | case Instruction::Load: |
| 1076 | if (MDNode *MD = |
| 1077 | Q.IIQ.getMetadata(cast<LoadInst>(I), LLVMContext::MD_range)) |
| 1078 | computeKnownBitsFromRangeMetadata(*MD, Known); |
| 1079 | break; |
| 1080 | case Instruction::And: { |
| 1081 | // If either the LHS or the RHS are Zero, the result is zero. |
| 1082 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); |
| 1083 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); |
| 1084 | |
| 1085 | Known &= Known2; |
| 1086 | |
| 1087 | // and(x, add (x, -1)) is a common idiom that always clears the low bit; |
| 1088 | // here we handle the more general case of adding any odd number by |
| 1089 | // matching the form add(x, add(x, y)) where y is odd. |
| 1090 | // TODO: This could be generalized to clearing any bit set in y where the |
| 1091 | // following bit is known to be unset in y. |
| 1092 | Value *X = nullptr, *Y = nullptr; |
| 1093 | if (!Known.Zero[0] && !Known.One[0] && |
| 1094 | match(I, m_c_BinOp(m_Value(X), m_Add(m_Deferred(X), m_Value(Y))))) { |
| 1095 | Known2.resetAll(); |
| 1096 | computeKnownBits(Y, DemandedElts, Known2, Depth + 1, Q); |
| 1097 | if (Known2.countMinTrailingOnes() > 0) |
| 1098 | Known.Zero.setBit(0); |
| 1099 | } |
| 1100 | break; |
| 1101 | } |
| 1102 | case Instruction::Or: |
| 1103 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); |
| 1104 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); |
| 1105 | |
| 1106 | Known |= Known2; |
| 1107 | break; |
| 1108 | case Instruction::Xor: |
| 1109 | computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q); |
| 1110 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); |
| 1111 | |
| 1112 | Known ^= Known2; |
| 1113 | break; |
| 1114 | case Instruction::Mul: { |
| 1115 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); |
| 1116 | computeKnownBitsMul(I->getOperand(0), I->getOperand(1), NSW, DemandedElts, |
| 1117 | Known, Known2, Depth, Q); |
| 1118 | break; |
| 1119 | } |
| 1120 | case Instruction::UDiv: { |
| 1121 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1122 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1123 | Known = KnownBits::udiv(Known, Known2); |
| 1124 | break; |
| 1125 | } |
| 1126 | case Instruction::Select: { |
| 1127 | const Value *LHS = nullptr, *RHS = nullptr; |
| 1128 | SelectPatternFlavor SPF = matchSelectPattern(I, LHS, RHS).Flavor; |
| 1129 | if (SelectPatternResult::isMinOrMax(SPF)) { |
| 1130 | computeKnownBits(RHS, Known, Depth + 1, Q); |
| 1131 | computeKnownBits(LHS, Known2, Depth + 1, Q); |
| 1132 | switch (SPF) { |
| 1133 | default: |
| 1134 | llvm_unreachable("Unhandled select pattern flavor!")::llvm::llvm_unreachable_internal("Unhandled select pattern flavor!" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1134); |
| 1135 | case SPF_SMAX: |
| 1136 | Known = KnownBits::smax(Known, Known2); |
| 1137 | break; |
| 1138 | case SPF_SMIN: |
| 1139 | Known = KnownBits::smin(Known, Known2); |
| 1140 | break; |
| 1141 | case SPF_UMAX: |
| 1142 | Known = KnownBits::umax(Known, Known2); |
| 1143 | break; |
| 1144 | case SPF_UMIN: |
| 1145 | Known = KnownBits::umin(Known, Known2); |
| 1146 | break; |
| 1147 | } |
| 1148 | break; |
| 1149 | } |
| 1150 | |
| 1151 | computeKnownBits(I->getOperand(2), Known, Depth + 1, Q); |
| 1152 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1153 | |
| 1154 | // Only known if known in both the LHS and RHS. |
| 1155 | Known = KnownBits::commonBits(Known, Known2); |
| 1156 | |
| 1157 | if (SPF == SPF_ABS) { |
| 1158 | // RHS from matchSelectPattern returns the negation part of abs pattern. |
| 1159 | // If the negate has an NSW flag we can assume the sign bit of the result |
| 1160 | // will be 0 because that makes abs(INT_MIN) undefined. |
| 1161 | if (match(RHS, m_Neg(m_Specific(LHS))) && |
| 1162 | Q.IIQ.hasNoSignedWrap(cast<Instruction>(RHS))) |
| 1163 | Known.Zero.setSignBit(); |
| 1164 | } |
| 1165 | |
| 1166 | break; |
| 1167 | } |
| 1168 | case Instruction::FPTrunc: |
| 1169 | case Instruction::FPExt: |
| 1170 | case Instruction::FPToUI: |
| 1171 | case Instruction::FPToSI: |
| 1172 | case Instruction::SIToFP: |
| 1173 | case Instruction::UIToFP: |
| 1174 | break; // Can't work with floating point. |
| 1175 | case Instruction::PtrToInt: |
| 1176 | case Instruction::IntToPtr: |
| 1177 | // Fall through and handle them the same as zext/trunc. |
| 1178 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; |
| 1179 | case Instruction::ZExt: |
| 1180 | case Instruction::Trunc: { |
| 1181 | Type *SrcTy = I->getOperand(0)->getType(); |
| 1182 | |
| 1183 | unsigned SrcBitWidth; |
| 1184 | // Note that we handle pointer operands here because of inttoptr/ptrtoint |
| 1185 | // which fall through here. |
| 1186 | Type *ScalarTy = SrcTy->getScalarType(); |
| 1187 | SrcBitWidth = ScalarTy->isPointerTy() ? |
| 1188 | Q.DL.getPointerTypeSizeInBits(ScalarTy) : |
| 1189 | Q.DL.getTypeSizeInBits(ScalarTy); |
| 1190 | |
| 1191 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1191, __PRETTY_FUNCTION__)); |
| 1192 | Known = Known.anyextOrTrunc(SrcBitWidth); |
| 1193 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1194 | Known = Known.zextOrTrunc(BitWidth); |
| 1195 | break; |
| 1196 | } |
| 1197 | case Instruction::BitCast: { |
| 1198 | Type *SrcTy = I->getOperand(0)->getType(); |
| 1199 | if (SrcTy->isIntOrPtrTy() && |
| 1200 | // TODO: For now, not handling conversions like: |
| 1201 | // (bitcast i64 %x to <2 x i32>) |
| 1202 | !I->getType()->isVectorTy()) { |
| 1203 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1204 | break; |
| 1205 | } |
| 1206 | break; |
| 1207 | } |
| 1208 | case Instruction::SExt: { |
| 1209 | // Compute the bits in the result that are not present in the input. |
| 1210 | unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits(); |
| 1211 | |
| 1212 | Known = Known.trunc(SrcBitWidth); |
| 1213 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1214 | // If the sign bit of the input is known set or clear, then we know the |
| 1215 | // top bits of the result. |
| 1216 | Known = Known.sext(BitWidth); |
| 1217 | break; |
| 1218 | } |
| 1219 | case Instruction::Shl: { |
| 1220 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); |
| 1221 | auto KF = [NSW](const KnownBits &KnownVal, const KnownBits &KnownAmt) { |
| 1222 | KnownBits Result = KnownBits::shl(KnownVal, KnownAmt); |
| 1223 | // If this shift has "nsw" keyword, then the result is either a poison |
| 1224 | // value or has the same sign bit as the first operand. |
| 1225 | if (NSW) { |
| 1226 | if (KnownVal.Zero.isSignBitSet()) |
| 1227 | Result.Zero.setSignBit(); |
| 1228 | if (KnownVal.One.isSignBitSet()) |
| 1229 | Result.One.setSignBit(); |
| 1230 | } |
| 1231 | return Result; |
| 1232 | }; |
| 1233 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, |
| 1234 | KF); |
| 1235 | // Trailing zeros of a right-shifted constant never decrease. |
| 1236 | const APInt *C; |
| 1237 | if (match(I->getOperand(0), m_APInt(C))) |
| 1238 | Known.Zero.setLowBits(C->countTrailingZeros()); |
| 1239 | break; |
| 1240 | } |
| 1241 | case Instruction::LShr: { |
| 1242 | auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) { |
| 1243 | return KnownBits::lshr(KnownVal, KnownAmt); |
| 1244 | }; |
| 1245 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, |
| 1246 | KF); |
| 1247 | // Leading zeros of a left-shifted constant never decrease. |
| 1248 | const APInt *C; |
| 1249 | if (match(I->getOperand(0), m_APInt(C))) |
| 1250 | Known.Zero.setHighBits(C->countLeadingZeros()); |
| 1251 | break; |
| 1252 | } |
| 1253 | case Instruction::AShr: { |
| 1254 | auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) { |
| 1255 | return KnownBits::ashr(KnownVal, KnownAmt); |
| 1256 | }; |
| 1257 | computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q, |
| 1258 | KF); |
| 1259 | break; |
| 1260 | } |
| 1261 | case Instruction::Sub: { |
| 1262 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); |
| 1263 | computeKnownBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW, |
| 1264 | DemandedElts, Known, Known2, Depth, Q); |
| 1265 | break; |
| 1266 | } |
| 1267 | case Instruction::Add: { |
| 1268 | bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I)); |
| 1269 | computeKnownBitsAddSub(true, I->getOperand(0), I->getOperand(1), NSW, |
| 1270 | DemandedElts, Known, Known2, Depth, Q); |
| 1271 | break; |
| 1272 | } |
| 1273 | case Instruction::SRem: |
| 1274 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1275 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1276 | Known = KnownBits::srem(Known, Known2); |
| 1277 | break; |
| 1278 | |
| 1279 | case Instruction::URem: |
| 1280 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1281 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1282 | Known = KnownBits::urem(Known, Known2); |
| 1283 | break; |
| 1284 | case Instruction::Alloca: |
| 1285 | Known.Zero.setLowBits(Log2(cast<AllocaInst>(I)->getAlign())); |
| 1286 | break; |
| 1287 | case Instruction::GetElementPtr: { |
| 1288 | // Analyze all of the subscripts of this getelementptr instruction |
| 1289 | // to determine if we can prove known low zero bits. |
| 1290 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1291 | // Accumulate the constant indices in a separate variable |
| 1292 | // to minimize the number of calls to computeForAddSub. |
| 1293 | APInt AccConstIndices(BitWidth, 0, /*IsSigned*/ true); |
| 1294 | |
| 1295 | gep_type_iterator GTI = gep_type_begin(I); |
| 1296 | for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) { |
| 1297 | // TrailZ can only become smaller, short-circuit if we hit zero. |
| 1298 | if (Known.isUnknown()) |
| 1299 | break; |
| 1300 | |
| 1301 | Value *Index = I->getOperand(i); |
| 1302 | |
| 1303 | // Handle case when index is zero. |
| 1304 | Constant *CIndex = dyn_cast<Constant>(Index); |
| 1305 | if (CIndex && CIndex->isZeroValue()) |
| 1306 | continue; |
| 1307 | |
| 1308 | if (StructType *STy = GTI.getStructTypeOrNull()) { |
| 1309 | // Handle struct member offset arithmetic. |
| 1310 | |
| 1311 | assert(CIndex &&((CIndex && "Access to structure field must be known at compile time" ) ? static_cast<void> (0) : __assert_fail ("CIndex && \"Access to structure field must be known at compile time\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1312, __PRETTY_FUNCTION__)) |
| 1312 | "Access to structure field must be known at compile time")((CIndex && "Access to structure field must be known at compile time" ) ? static_cast<void> (0) : __assert_fail ("CIndex && \"Access to structure field must be known at compile time\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1312, __PRETTY_FUNCTION__)); |
| 1313 | |
| 1314 | if (CIndex->getType()->isVectorTy()) |
| 1315 | Index = CIndex->getSplatValue(); |
| 1316 | |
| 1317 | unsigned Idx = cast<ConstantInt>(Index)->getZExtValue(); |
| 1318 | const StructLayout *SL = Q.DL.getStructLayout(STy); |
| 1319 | uint64_t Offset = SL->getElementOffset(Idx); |
| 1320 | AccConstIndices += Offset; |
| 1321 | continue; |
| 1322 | } |
| 1323 | |
| 1324 | // Handle array index arithmetic. |
| 1325 | Type *IndexedTy = GTI.getIndexedType(); |
| 1326 | if (!IndexedTy->isSized()) { |
| 1327 | Known.resetAll(); |
| 1328 | break; |
| 1329 | } |
| 1330 | |
| 1331 | unsigned IndexBitWidth = Index->getType()->getScalarSizeInBits(); |
| 1332 | KnownBits IndexBits(IndexBitWidth); |
| 1333 | computeKnownBits(Index, IndexBits, Depth + 1, Q); |
| 1334 | TypeSize IndexTypeSize = Q.DL.getTypeAllocSize(IndexedTy); |
| 1335 | uint64_t TypeSizeInBytes = IndexTypeSize.getKnownMinSize(); |
| 1336 | KnownBits ScalingFactor(IndexBitWidth); |
| 1337 | // Multiply by current sizeof type. |
| 1338 | // &A[i] == A + i * sizeof(*A[i]). |
| 1339 | if (IndexTypeSize.isScalable()) { |
| 1340 | // For scalable types the only thing we know about sizeof is |
| 1341 | // that this is a multiple of the minimum size. |
| 1342 | ScalingFactor.Zero.setLowBits(countTrailingZeros(TypeSizeInBytes)); |
| 1343 | } else if (IndexBits.isConstant()) { |
| 1344 | APInt IndexConst = IndexBits.getConstant(); |
| 1345 | APInt ScalingFactor(IndexBitWidth, TypeSizeInBytes); |
| 1346 | IndexConst *= ScalingFactor; |
| 1347 | AccConstIndices += IndexConst.sextOrTrunc(BitWidth); |
| 1348 | continue; |
| 1349 | } else { |
| 1350 | ScalingFactor = |
| 1351 | KnownBits::makeConstant(APInt(IndexBitWidth, TypeSizeInBytes)); |
| 1352 | } |
| 1353 | IndexBits = KnownBits::computeForMul(IndexBits, ScalingFactor); |
| 1354 | |
| 1355 | // If the offsets have a different width from the pointer, according |
| 1356 | // to the language reference we need to sign-extend or truncate them |
| 1357 | // to the width of the pointer. |
| 1358 | IndexBits = IndexBits.sextOrTrunc(BitWidth); |
| 1359 | |
| 1360 | // Note that inbounds does *not* guarantee nsw for the addition, as only |
| 1361 | // the offset is signed, while the base address is unsigned. |
| 1362 | Known = KnownBits::computeForAddSub( |
| 1363 | /*Add=*/true, /*NSW=*/false, Known, IndexBits); |
| 1364 | } |
| 1365 | if (!Known.isUnknown() && !AccConstIndices.isNullValue()) { |
| 1366 | KnownBits Index = KnownBits::makeConstant(AccConstIndices); |
| 1367 | Known = KnownBits::computeForAddSub( |
| 1368 | /*Add=*/true, /*NSW=*/false, Known, Index); |
| 1369 | } |
| 1370 | break; |
| 1371 | } |
| 1372 | case Instruction::PHI: { |
| 1373 | const PHINode *P = cast<PHINode>(I); |
| 1374 | // Handle the case of a simple two-predecessor recurrence PHI. |
| 1375 | // There's a lot more that could theoretically be done here, but |
| 1376 | // this is sufficient to catch some interesting cases. |
| 1377 | if (P->getNumIncomingValues() == 2) { |
| 1378 | for (unsigned i = 0; i != 2; ++i) { |
| 1379 | Value *L = P->getIncomingValue(i); |
| 1380 | Value *R = P->getIncomingValue(!i); |
| 1381 | Instruction *RInst = P->getIncomingBlock(!i)->getTerminator(); |
| 1382 | Instruction *LInst = P->getIncomingBlock(i)->getTerminator(); |
| 1383 | Operator *LU = dyn_cast<Operator>(L); |
| 1384 | if (!LU) |
| 1385 | continue; |
| 1386 | unsigned Opcode = LU->getOpcode(); |
| 1387 | |
| 1388 | |
| 1389 | // If this is a shift recurrence, we know the bits being shifted in. |
| 1390 | // We can combine that with information about the start value of the |
| 1391 | // recurrence to conclude facts about the result. |
| 1392 | if (Opcode == Instruction::LShr || |
| 1393 | Opcode == Instruction::AShr || |
| 1394 | Opcode == Instruction::Shl) { |
| 1395 | Value *LL = LU->getOperand(0); |
| 1396 | Value *LR = LU->getOperand(1); |
| 1397 | // Find a recurrence. |
| 1398 | if (LL == I) |
| 1399 | L = LR; |
Value stored to 'L' is never read | |
| 1400 | else |
| 1401 | continue; // Check for recurrence with L and R flipped. |
| 1402 | |
| 1403 | // We have matched a recurrence of the form: |
| 1404 | // %iv = [R, %entry], [%iv.next, %backedge] |
| 1405 | // %iv.next = shift_op %iv, L |
| 1406 | |
| 1407 | // Recurse with the phi context to avoid concern about whether facts |
| 1408 | // inferred hold at original context instruction. TODO: It may be |
| 1409 | // correct to use the original context. IF warranted, explore and |
| 1410 | // add sufficient tests to cover. |
| 1411 | Query RecQ = Q; |
| 1412 | RecQ.CxtI = P; |
| 1413 | computeKnownBits(R, DemandedElts, Known2, Depth + 1, RecQ); |
| 1414 | switch (Opcode) { |
| 1415 | case Instruction::Shl: |
| 1416 | // A shl recurrence will only increase the tailing zeros |
| 1417 | Known.Zero.setLowBits(Known2.countMinTrailingZeros()); |
| 1418 | break; |
| 1419 | case Instruction::LShr: |
| 1420 | // A lshr recurrence will preserve the leading zeros of the |
| 1421 | // start value |
| 1422 | Known.Zero.setHighBits(Known2.countMinLeadingZeros()); |
| 1423 | break; |
| 1424 | case Instruction::AShr: |
| 1425 | // An ashr recurrence will extend the initial sign bit |
| 1426 | Known.Zero.setHighBits(Known2.countMinLeadingZeros()); |
| 1427 | Known.One.setHighBits(Known2.countMinLeadingOnes()); |
| 1428 | break; |
| 1429 | }; |
| 1430 | } |
| 1431 | |
| 1432 | // Check for operations that have the property that if |
| 1433 | // both their operands have low zero bits, the result |
| 1434 | // will have low zero bits. |
| 1435 | if (Opcode == Instruction::Add || |
| 1436 | Opcode == Instruction::Sub || |
| 1437 | Opcode == Instruction::And || |
| 1438 | Opcode == Instruction::Or || |
| 1439 | Opcode == Instruction::Mul) { |
| 1440 | Value *LL = LU->getOperand(0); |
| 1441 | Value *LR = LU->getOperand(1); |
| 1442 | // Find a recurrence. |
| 1443 | if (LL == I) |
| 1444 | L = LR; |
| 1445 | else if (LR == I) |
| 1446 | L = LL; |
| 1447 | else |
| 1448 | continue; // Check for recurrence with L and R flipped. |
| 1449 | |
| 1450 | // Change the context instruction to the "edge" that flows into the |
| 1451 | // phi. This is important because that is where the value is actually |
| 1452 | // "evaluated" even though it is used later somewhere else. (see also |
| 1453 | // D69571). |
| 1454 | Query RecQ = Q; |
| 1455 | |
| 1456 | // Ok, we have a PHI of the form L op= R. Check for low |
| 1457 | // zero bits. |
| 1458 | RecQ.CxtI = RInst; |
| 1459 | computeKnownBits(R, Known2, Depth + 1, RecQ); |
| 1460 | |
| 1461 | // We need to take the minimum number of known bits |
| 1462 | KnownBits Known3(BitWidth); |
| 1463 | RecQ.CxtI = LInst; |
| 1464 | computeKnownBits(L, Known3, Depth + 1, RecQ); |
| 1465 | |
| 1466 | Known.Zero.setLowBits(std::min(Known2.countMinTrailingZeros(), |
| 1467 | Known3.countMinTrailingZeros())); |
| 1468 | |
| 1469 | auto *OverflowOp = dyn_cast<OverflowingBinaryOperator>(LU); |
| 1470 | if (OverflowOp && Q.IIQ.hasNoSignedWrap(OverflowOp)) { |
| 1471 | // If initial value of recurrence is nonnegative, and we are adding |
| 1472 | // a nonnegative number with nsw, the result can only be nonnegative |
| 1473 | // or poison value regardless of the number of times we execute the |
| 1474 | // add in phi recurrence. If initial value is negative and we are |
| 1475 | // adding a negative number with nsw, the result can only be |
| 1476 | // negative or poison value. Similar arguments apply to sub and mul. |
| 1477 | // |
| 1478 | // (add non-negative, non-negative) --> non-negative |
| 1479 | // (add negative, negative) --> negative |
| 1480 | if (Opcode == Instruction::Add) { |
| 1481 | if (Known2.isNonNegative() && Known3.isNonNegative()) |
| 1482 | Known.makeNonNegative(); |
| 1483 | else if (Known2.isNegative() && Known3.isNegative()) |
| 1484 | Known.makeNegative(); |
| 1485 | } |
| 1486 | |
| 1487 | // (sub nsw non-negative, negative) --> non-negative |
| 1488 | // (sub nsw negative, non-negative) --> negative |
| 1489 | else if (Opcode == Instruction::Sub && LL == I) { |
| 1490 | if (Known2.isNonNegative() && Known3.isNegative()) |
| 1491 | Known.makeNonNegative(); |
| 1492 | else if (Known2.isNegative() && Known3.isNonNegative()) |
| 1493 | Known.makeNegative(); |
| 1494 | } |
| 1495 | |
| 1496 | // (mul nsw non-negative, non-negative) --> non-negative |
| 1497 | else if (Opcode == Instruction::Mul && Known2.isNonNegative() && |
| 1498 | Known3.isNonNegative()) |
| 1499 | Known.makeNonNegative(); |
| 1500 | } |
| 1501 | |
| 1502 | break; |
| 1503 | } |
| 1504 | } |
| 1505 | } |
| 1506 | |
| 1507 | // Unreachable blocks may have zero-operand PHI nodes. |
| 1508 | if (P->getNumIncomingValues() == 0) |
| 1509 | break; |
| 1510 | |
| 1511 | // Otherwise take the unions of the known bit sets of the operands, |
| 1512 | // taking conservative care to avoid excessive recursion. |
| 1513 | if (Depth < MaxAnalysisRecursionDepth - 1 && !Known.Zero && !Known.One) { |
| 1514 | // Skip if every incoming value references to ourself. |
| 1515 | if (dyn_cast_or_null<UndefValue>(P->hasConstantValue())) |
| 1516 | break; |
| 1517 | |
| 1518 | Known.Zero.setAllBits(); |
| 1519 | Known.One.setAllBits(); |
| 1520 | for (unsigned u = 0, e = P->getNumIncomingValues(); u < e; ++u) { |
| 1521 | Value *IncValue = P->getIncomingValue(u); |
| 1522 | // Skip direct self references. |
| 1523 | if (IncValue == P) continue; |
| 1524 | |
| 1525 | // Change the context instruction to the "edge" that flows into the |
| 1526 | // phi. This is important because that is where the value is actually |
| 1527 | // "evaluated" even though it is used later somewhere else. (see also |
| 1528 | // D69571). |
| 1529 | Query RecQ = Q; |
| 1530 | RecQ.CxtI = P->getIncomingBlock(u)->getTerminator(); |
| 1531 | |
| 1532 | Known2 = KnownBits(BitWidth); |
| 1533 | // Recurse, but cap the recursion to one level, because we don't |
| 1534 | // want to waste time spinning around in loops. |
| 1535 | computeKnownBits(IncValue, Known2, MaxAnalysisRecursionDepth - 1, RecQ); |
| 1536 | Known = KnownBits::commonBits(Known, Known2); |
| 1537 | // If all bits have been ruled out, there's no need to check |
| 1538 | // more operands. |
| 1539 | if (Known.isUnknown()) |
| 1540 | break; |
| 1541 | } |
| 1542 | } |
| 1543 | break; |
| 1544 | } |
| 1545 | case Instruction::Call: |
| 1546 | case Instruction::Invoke: |
| 1547 | // If range metadata is attached to this call, set known bits from that, |
| 1548 | // and then intersect with known bits based on other properties of the |
| 1549 | // function. |
| 1550 | if (MDNode *MD = |
| 1551 | Q.IIQ.getMetadata(cast<Instruction>(I), LLVMContext::MD_range)) |
| 1552 | computeKnownBitsFromRangeMetadata(*MD, Known); |
| 1553 | if (const Value *RV = cast<CallBase>(I)->getReturnedArgOperand()) { |
| 1554 | computeKnownBits(RV, Known2, Depth + 1, Q); |
| 1555 | Known.Zero |= Known2.Zero; |
| 1556 | Known.One |= Known2.One; |
| 1557 | } |
| 1558 | if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { |
| 1559 | switch (II->getIntrinsicID()) { |
| 1560 | default: break; |
| 1561 | case Intrinsic::abs: { |
| 1562 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); |
| 1563 | bool IntMinIsPoison = match(II->getArgOperand(1), m_One()); |
| 1564 | Known = Known2.abs(IntMinIsPoison); |
| 1565 | break; |
| 1566 | } |
| 1567 | case Intrinsic::bitreverse: |
| 1568 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); |
| 1569 | Known.Zero |= Known2.Zero.reverseBits(); |
| 1570 | Known.One |= Known2.One.reverseBits(); |
| 1571 | break; |
| 1572 | case Intrinsic::bswap: |
| 1573 | computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q); |
| 1574 | Known.Zero |= Known2.Zero.byteSwap(); |
| 1575 | Known.One |= Known2.One.byteSwap(); |
| 1576 | break; |
| 1577 | case Intrinsic::ctlz: { |
| 1578 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); |
| 1579 | // If we have a known 1, its position is our upper bound. |
| 1580 | unsigned PossibleLZ = Known2.countMaxLeadingZeros(); |
| 1581 | // If this call is undefined for 0, the result will be less than 2^n. |
| 1582 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) |
| 1583 | PossibleLZ = std::min(PossibleLZ, BitWidth - 1); |
| 1584 | unsigned LowBits = Log2_32(PossibleLZ)+1; |
| 1585 | Known.Zero.setBitsFrom(LowBits); |
| 1586 | break; |
| 1587 | } |
| 1588 | case Intrinsic::cttz: { |
| 1589 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); |
| 1590 | // If we have a known 1, its position is our upper bound. |
| 1591 | unsigned PossibleTZ = Known2.countMaxTrailingZeros(); |
| 1592 | // If this call is undefined for 0, the result will be less than 2^n. |
| 1593 | if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext())) |
| 1594 | PossibleTZ = std::min(PossibleTZ, BitWidth - 1); |
| 1595 | unsigned LowBits = Log2_32(PossibleTZ)+1; |
| 1596 | Known.Zero.setBitsFrom(LowBits); |
| 1597 | break; |
| 1598 | } |
| 1599 | case Intrinsic::ctpop: { |
| 1600 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); |
| 1601 | // We can bound the space the count needs. Also, bits known to be zero |
| 1602 | // can't contribute to the population. |
| 1603 | unsigned BitsPossiblySet = Known2.countMaxPopulation(); |
| 1604 | unsigned LowBits = Log2_32(BitsPossiblySet)+1; |
| 1605 | Known.Zero.setBitsFrom(LowBits); |
| 1606 | // TODO: we could bound KnownOne using the lower bound on the number |
| 1607 | // of bits which might be set provided by popcnt KnownOne2. |
| 1608 | break; |
| 1609 | } |
| 1610 | case Intrinsic::fshr: |
| 1611 | case Intrinsic::fshl: { |
| 1612 | const APInt *SA; |
| 1613 | if (!match(I->getOperand(2), m_APInt(SA))) |
| 1614 | break; |
| 1615 | |
| 1616 | // Normalize to funnel shift left. |
| 1617 | uint64_t ShiftAmt = SA->urem(BitWidth); |
| 1618 | if (II->getIntrinsicID() == Intrinsic::fshr) |
| 1619 | ShiftAmt = BitWidth - ShiftAmt; |
| 1620 | |
| 1621 | KnownBits Known3(BitWidth); |
| 1622 | computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q); |
| 1623 | computeKnownBits(I->getOperand(1), Known3, Depth + 1, Q); |
| 1624 | |
| 1625 | Known.Zero = |
| 1626 | Known2.Zero.shl(ShiftAmt) | Known3.Zero.lshr(BitWidth - ShiftAmt); |
| 1627 | Known.One = |
| 1628 | Known2.One.shl(ShiftAmt) | Known3.One.lshr(BitWidth - ShiftAmt); |
| 1629 | break; |
| 1630 | } |
| 1631 | case Intrinsic::uadd_sat: |
| 1632 | case Intrinsic::usub_sat: { |
| 1633 | bool IsAdd = II->getIntrinsicID() == Intrinsic::uadd_sat; |
| 1634 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1635 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1636 | |
| 1637 | // Add: Leading ones of either operand are preserved. |
| 1638 | // Sub: Leading zeros of LHS and leading ones of RHS are preserved |
| 1639 | // as leading zeros in the result. |
| 1640 | unsigned LeadingKnown; |
| 1641 | if (IsAdd) |
| 1642 | LeadingKnown = std::max(Known.countMinLeadingOnes(), |
| 1643 | Known2.countMinLeadingOnes()); |
| 1644 | else |
| 1645 | LeadingKnown = std::max(Known.countMinLeadingZeros(), |
| 1646 | Known2.countMinLeadingOnes()); |
| 1647 | |
| 1648 | Known = KnownBits::computeForAddSub( |
| 1649 | IsAdd, /* NSW */ false, Known, Known2); |
| 1650 | |
| 1651 | // We select between the operation result and all-ones/zero |
| 1652 | // respectively, so we can preserve known ones/zeros. |
| 1653 | if (IsAdd) { |
| 1654 | Known.One.setHighBits(LeadingKnown); |
| 1655 | Known.Zero.clearAllBits(); |
| 1656 | } else { |
| 1657 | Known.Zero.setHighBits(LeadingKnown); |
| 1658 | Known.One.clearAllBits(); |
| 1659 | } |
| 1660 | break; |
| 1661 | } |
| 1662 | case Intrinsic::umin: |
| 1663 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1664 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1665 | Known = KnownBits::umin(Known, Known2); |
| 1666 | break; |
| 1667 | case Intrinsic::umax: |
| 1668 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1669 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1670 | Known = KnownBits::umax(Known, Known2); |
| 1671 | break; |
| 1672 | case Intrinsic::smin: |
| 1673 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1674 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1675 | Known = KnownBits::smin(Known, Known2); |
| 1676 | break; |
| 1677 | case Intrinsic::smax: |
| 1678 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1679 | computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q); |
| 1680 | Known = KnownBits::smax(Known, Known2); |
| 1681 | break; |
| 1682 | case Intrinsic::x86_sse42_crc32_64_64: |
| 1683 | Known.Zero.setBitsFrom(32); |
| 1684 | break; |
| 1685 | } |
| 1686 | } |
| 1687 | break; |
| 1688 | case Instruction::ShuffleVector: { |
| 1689 | auto *Shuf = dyn_cast<ShuffleVectorInst>(I); |
| 1690 | // FIXME: Do we need to handle ConstantExpr involving shufflevectors? |
| 1691 | if (!Shuf) { |
| 1692 | Known.resetAll(); |
| 1693 | return; |
| 1694 | } |
| 1695 | // For undef elements, we don't know anything about the common state of |
| 1696 | // the shuffle result. |
| 1697 | APInt DemandedLHS, DemandedRHS; |
| 1698 | if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) { |
| 1699 | Known.resetAll(); |
| 1700 | return; |
| 1701 | } |
| 1702 | Known.One.setAllBits(); |
| 1703 | Known.Zero.setAllBits(); |
| 1704 | if (!!DemandedLHS) { |
| 1705 | const Value *LHS = Shuf->getOperand(0); |
| 1706 | computeKnownBits(LHS, DemandedLHS, Known, Depth + 1, Q); |
| 1707 | // If we don't know any bits, early out. |
| 1708 | if (Known.isUnknown()) |
| 1709 | break; |
| 1710 | } |
| 1711 | if (!!DemandedRHS) { |
| 1712 | const Value *RHS = Shuf->getOperand(1); |
| 1713 | computeKnownBits(RHS, DemandedRHS, Known2, Depth + 1, Q); |
| 1714 | Known = KnownBits::commonBits(Known, Known2); |
| 1715 | } |
| 1716 | break; |
| 1717 | } |
| 1718 | case Instruction::InsertElement: { |
| 1719 | const Value *Vec = I->getOperand(0); |
| 1720 | const Value *Elt = I->getOperand(1); |
| 1721 | auto *CIdx = dyn_cast<ConstantInt>(I->getOperand(2)); |
| 1722 | // Early out if the index is non-constant or out-of-range. |
| 1723 | unsigned NumElts = DemandedElts.getBitWidth(); |
| 1724 | if (!CIdx || CIdx->getValue().uge(NumElts)) { |
| 1725 | Known.resetAll(); |
| 1726 | return; |
| 1727 | } |
| 1728 | Known.One.setAllBits(); |
| 1729 | Known.Zero.setAllBits(); |
| 1730 | unsigned EltIdx = CIdx->getZExtValue(); |
| 1731 | // Do we demand the inserted element? |
| 1732 | if (DemandedElts[EltIdx]) { |
| 1733 | computeKnownBits(Elt, Known, Depth + 1, Q); |
| 1734 | // If we don't know any bits, early out. |
| 1735 | if (Known.isUnknown()) |
| 1736 | break; |
| 1737 | } |
| 1738 | // We don't need the base vector element that has been inserted. |
| 1739 | APInt DemandedVecElts = DemandedElts; |
| 1740 | DemandedVecElts.clearBit(EltIdx); |
| 1741 | if (!!DemandedVecElts) { |
| 1742 | computeKnownBits(Vec, DemandedVecElts, Known2, Depth + 1, Q); |
| 1743 | Known = KnownBits::commonBits(Known, Known2); |
| 1744 | } |
| 1745 | break; |
| 1746 | } |
| 1747 | case Instruction::ExtractElement: { |
| 1748 | // Look through extract element. If the index is non-constant or |
| 1749 | // out-of-range demand all elements, otherwise just the extracted element. |
| 1750 | const Value *Vec = I->getOperand(0); |
| 1751 | const Value *Idx = I->getOperand(1); |
| 1752 | auto *CIdx = dyn_cast<ConstantInt>(Idx); |
| 1753 | if (isa<ScalableVectorType>(Vec->getType())) { |
| 1754 | // FIXME: there's probably *something* we can do with scalable vectors |
| 1755 | Known.resetAll(); |
| 1756 | break; |
| 1757 | } |
| 1758 | unsigned NumElts = cast<FixedVectorType>(Vec->getType())->getNumElements(); |
| 1759 | APInt DemandedVecElts = APInt::getAllOnesValue(NumElts); |
| 1760 | if (CIdx && CIdx->getValue().ult(NumElts)) |
| 1761 | DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue()); |
| 1762 | computeKnownBits(Vec, DemandedVecElts, Known, Depth + 1, Q); |
| 1763 | break; |
| 1764 | } |
| 1765 | case Instruction::ExtractValue: |
| 1766 | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I->getOperand(0))) { |
| 1767 | const ExtractValueInst *EVI = cast<ExtractValueInst>(I); |
| 1768 | if (EVI->getNumIndices() != 1) break; |
| 1769 | if (EVI->getIndices()[0] == 0) { |
| 1770 | switch (II->getIntrinsicID()) { |
| 1771 | default: break; |
| 1772 | case Intrinsic::uadd_with_overflow: |
| 1773 | case Intrinsic::sadd_with_overflow: |
| 1774 | computeKnownBitsAddSub(true, II->getArgOperand(0), |
| 1775 | II->getArgOperand(1), false, DemandedElts, |
| 1776 | Known, Known2, Depth, Q); |
| 1777 | break; |
| 1778 | case Intrinsic::usub_with_overflow: |
| 1779 | case Intrinsic::ssub_with_overflow: |
| 1780 | computeKnownBitsAddSub(false, II->getArgOperand(0), |
| 1781 | II->getArgOperand(1), false, DemandedElts, |
| 1782 | Known, Known2, Depth, Q); |
| 1783 | break; |
| 1784 | case Intrinsic::umul_with_overflow: |
| 1785 | case Intrinsic::smul_with_overflow: |
| 1786 | computeKnownBitsMul(II->getArgOperand(0), II->getArgOperand(1), false, |
| 1787 | DemandedElts, Known, Known2, Depth, Q); |
| 1788 | break; |
| 1789 | } |
| 1790 | } |
| 1791 | } |
| 1792 | break; |
| 1793 | case Instruction::Freeze: |
| 1794 | if (isGuaranteedNotToBePoison(I->getOperand(0), Q.AC, Q.CxtI, Q.DT, |
| 1795 | Depth + 1)) |
| 1796 | computeKnownBits(I->getOperand(0), Known, Depth + 1, Q); |
| 1797 | break; |
| 1798 | } |
| 1799 | } |
| 1800 | |
| 1801 | /// Determine which bits of V are known to be either zero or one and return |
| 1802 | /// them. |
| 1803 | KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts, |
| 1804 | unsigned Depth, const Query &Q) { |
| 1805 | KnownBits Known(getBitWidth(V->getType(), Q.DL)); |
| 1806 | computeKnownBits(V, DemandedElts, Known, Depth, Q); |
| 1807 | return Known; |
| 1808 | } |
| 1809 | |
| 1810 | /// Determine which bits of V are known to be either zero or one and return |
| 1811 | /// them. |
| 1812 | KnownBits computeKnownBits(const Value *V, unsigned Depth, const Query &Q) { |
| 1813 | KnownBits Known(getBitWidth(V->getType(), Q.DL)); |
| 1814 | computeKnownBits(V, Known, Depth, Q); |
| 1815 | return Known; |
| 1816 | } |
| 1817 | |
| 1818 | /// Determine which bits of V are known to be either zero or one and return |
| 1819 | /// them in the Known bit set. |
| 1820 | /// |
| 1821 | /// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that |
| 1822 | /// we cannot optimize based on the assumption that it is zero without changing |
| 1823 | /// it to be an explicit zero. If we don't change it to zero, other code could |
| 1824 | /// optimized based on the contradictory assumption that it is non-zero. |
| 1825 | /// Because instcombine aggressively folds operations with undef args anyway, |
| 1826 | /// this won't lose us code quality. |
| 1827 | /// |
| 1828 | /// This function is defined on values with integer type, values with pointer |
| 1829 | /// type, and vectors of integers. In the case |
| 1830 | /// where V is a vector, known zero, and known one values are the |
| 1831 | /// same width as the vector element, and the bit is set only if it is true |
| 1832 | /// for all of the demanded elements in the vector specified by DemandedElts. |
| 1833 | void computeKnownBits(const Value *V, const APInt &DemandedElts, |
| 1834 | KnownBits &Known, unsigned Depth, const Query &Q) { |
| 1835 | if (!DemandedElts || isa<ScalableVectorType>(V->getType())) { |
| 1836 | // No demanded elts or V is a scalable vector, better to assume we don't |
| 1837 | // know anything. |
| 1838 | Known.resetAll(); |
| 1839 | return; |
| 1840 | } |
| 1841 | |
| 1842 | assert(V && "No Value?")((V && "No Value?") ? static_cast<void> (0) : __assert_fail ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1842, __PRETTY_FUNCTION__)); |
| 1843 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")((Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth" ) ? static_cast<void> (0) : __assert_fail ("Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1843, __PRETTY_FUNCTION__)); |
| 1844 | |
| 1845 | #ifndef NDEBUG |
| 1846 | Type *Ty = V->getType(); |
| 1847 | unsigned BitWidth = Known.getBitWidth(); |
| 1848 | |
| 1849 | assert((Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) &&(((Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy ()) && "Not integer or pointer type!") ? static_cast< void> (0) : __assert_fail ("(Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1850, __PRETTY_FUNCTION__)) |
| 1850 | "Not integer or pointer type!")(((Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy ()) && "Not integer or pointer type!") ? static_cast< void> (0) : __assert_fail ("(Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1850, __PRETTY_FUNCTION__)); |
| 1851 | |
| 1852 | if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) { |
| 1853 | assert(((FVTy->getNumElements() == DemandedElts.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? static_cast<void> (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1855, __PRETTY_FUNCTION__)) |
| 1854 | FVTy->getNumElements() == DemandedElts.getBitWidth() &&((FVTy->getNumElements() == DemandedElts.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? static_cast<void> (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1855, __PRETTY_FUNCTION__)) |
| 1855 | "DemandedElt width should equal the fixed vector number of elements")((FVTy->getNumElements() == DemandedElts.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? static_cast<void> (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1855, __PRETTY_FUNCTION__)); |
| 1856 | } else { |
| 1857 | assert(DemandedElts == APInt(1, 1) &&((DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars" ) ? static_cast<void> (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1858, __PRETTY_FUNCTION__)) |
| 1858 | "DemandedElt width should be 1 for scalars")((DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars" ) ? static_cast<void> (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1858, __PRETTY_FUNCTION__)); |
| 1859 | } |
| 1860 | |
| 1861 | Type *ScalarTy = Ty->getScalarType(); |
| 1862 | if (ScalarTy->isPointerTy()) { |
| 1863 | assert(BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) &&((BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && "V and Known should have same BitWidth") ? static_cast<void > (0) : __assert_fail ("BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1864, __PRETTY_FUNCTION__)) |
| 1864 | "V and Known should have same BitWidth")((BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && "V and Known should have same BitWidth") ? static_cast<void > (0) : __assert_fail ("BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1864, __PRETTY_FUNCTION__)); |
| 1865 | } else { |
| 1866 | assert(BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) &&((BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && "V and Known should have same BitWidth" ) ? static_cast<void> (0) : __assert_fail ("BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1867, __PRETTY_FUNCTION__)) |
| 1867 | "V and Known should have same BitWidth")((BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && "V and Known should have same BitWidth" ) ? static_cast<void> (0) : __assert_fail ("BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1867, __PRETTY_FUNCTION__)); |
| 1868 | } |
| 1869 | #endif |
| 1870 | |
| 1871 | const APInt *C; |
| 1872 | if (match(V, m_APInt(C))) { |
| 1873 | // We know all of the bits for a scalar constant or a splat vector constant! |
| 1874 | Known = KnownBits::makeConstant(*C); |
| 1875 | return; |
| 1876 | } |
| 1877 | // Null and aggregate-zero are all-zeros. |
| 1878 | if (isa<ConstantPointerNull>(V) || isa<ConstantAggregateZero>(V)) { |
| 1879 | Known.setAllZero(); |
| 1880 | return; |
| 1881 | } |
| 1882 | // Handle a constant vector by taking the intersection of the known bits of |
| 1883 | // each element. |
| 1884 | if (const ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(V)) { |
| 1885 | // We know that CDV must be a vector of integers. Take the intersection of |
| 1886 | // each element. |
| 1887 | Known.Zero.setAllBits(); Known.One.setAllBits(); |
| 1888 | for (unsigned i = 0, e = CDV->getNumElements(); i != e; ++i) { |
| 1889 | if (!DemandedElts[i]) |
| 1890 | continue; |
| 1891 | APInt Elt = CDV->getElementAsAPInt(i); |
| 1892 | Known.Zero &= ~Elt; |
| 1893 | Known.One &= Elt; |
| 1894 | } |
| 1895 | return; |
| 1896 | } |
| 1897 | |
| 1898 | if (const auto *CV = dyn_cast<ConstantVector>(V)) { |
| 1899 | // We know that CV must be a vector of integers. Take the intersection of |
| 1900 | // each element. |
| 1901 | Known.Zero.setAllBits(); Known.One.setAllBits(); |
| 1902 | for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) { |
| 1903 | if (!DemandedElts[i]) |
| 1904 | continue; |
| 1905 | Constant *Element = CV->getAggregateElement(i); |
| 1906 | auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element); |
| 1907 | if (!ElementCI) { |
| 1908 | Known.resetAll(); |
| 1909 | return; |
| 1910 | } |
| 1911 | const APInt &Elt = ElementCI->getValue(); |
| 1912 | Known.Zero &= ~Elt; |
| 1913 | Known.One &= Elt; |
| 1914 | } |
| 1915 | return; |
| 1916 | } |
| 1917 | |
| 1918 | // Start out not knowing anything. |
| 1919 | Known.resetAll(); |
| 1920 | |
| 1921 | // We can't imply anything about undefs. |
| 1922 | if (isa<UndefValue>(V)) |
| 1923 | return; |
| 1924 | |
| 1925 | // There's no point in looking through other users of ConstantData for |
| 1926 | // assumptions. Confirm that we've handled them all. |
| 1927 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1927, __PRETTY_FUNCTION__)); |
| 1928 | |
| 1929 | // All recursive calls that increase depth must come after this. |
| 1930 | if (Depth == MaxAnalysisRecursionDepth) |
| 1931 | return; |
| 1932 | |
| 1933 | // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has |
| 1934 | // the bits of its aliasee. |
| 1935 | if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { |
| 1936 | if (!GA->isInterposable()) |
| 1937 | computeKnownBits(GA->getAliasee(), Known, Depth + 1, Q); |
| 1938 | return; |
| 1939 | } |
| 1940 | |
| 1941 | if (const Operator *I = dyn_cast<Operator>(V)) |
| 1942 | computeKnownBitsFromOperator(I, DemandedElts, Known, Depth, Q); |
| 1943 | |
| 1944 | // Aligned pointers have trailing zeros - refine Known.Zero set |
| 1945 | if (isa<PointerType>(V->getType())) { |
| 1946 | Align Alignment = V->getPointerAlignment(Q.DL); |
| 1947 | Known.Zero.setLowBits(Log2(Alignment)); |
| 1948 | } |
| 1949 | |
| 1950 | // computeKnownBitsFromAssume strictly refines Known. |
| 1951 | // Therefore, we run them after computeKnownBitsFromOperator. |
| 1952 | |
| 1953 | // Check whether a nearby assume intrinsic can determine some known bits. |
| 1954 | computeKnownBitsFromAssume(V, Known, Depth, Q); |
| 1955 | |
| 1956 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1956, __PRETTY_FUNCTION__)); |
| 1957 | } |
| 1958 | |
| 1959 | /// Return true if the given value is known to have exactly one |
| 1960 | /// bit set when defined. For vectors return true if every element is known to |
| 1961 | /// be a power of two when defined. Supports values with integer or pointer |
| 1962 | /// types and vectors of integers. |
| 1963 | bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth, |
| 1964 | const Query &Q) { |
| 1965 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")((Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth" ) ? static_cast<void> (0) : __assert_fail ("Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 1965, __PRETTY_FUNCTION__)); |
| 1966 | |
| 1967 | // Attempt to match against constants. |
| 1968 | if (OrZero && match(V, m_Power2OrZero())) |
| 1969 | return true; |
| 1970 | if (match(V, m_Power2())) |
| 1971 | return true; |
| 1972 | |
| 1973 | // 1 << X is clearly a power of two if the one is not shifted off the end. If |
| 1974 | // it is shifted off the end then the result is undefined. |
| 1975 | if (match(V, m_Shl(m_One(), m_Value()))) |
| 1976 | return true; |
| 1977 | |
| 1978 | // (signmask) >>l X is clearly a power of two if the one is not shifted off |
| 1979 | // the bottom. If it is shifted off the bottom then the result is undefined. |
| 1980 | if (match(V, m_LShr(m_SignMask(), m_Value()))) |
| 1981 | return true; |
| 1982 | |
| 1983 | // The remaining tests are all recursive, so bail out if we hit the limit. |
| 1984 | if (Depth++ == MaxAnalysisRecursionDepth) |
| 1985 | return false; |
| 1986 | |
| 1987 | Value *X = nullptr, *Y = nullptr; |
| 1988 | // A shift left or a logical shift right of a power of two is a power of two |
| 1989 | // or zero. |
| 1990 | if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) || |
| 1991 | match(V, m_LShr(m_Value(X), m_Value())))) |
| 1992 | return isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q); |
| 1993 | |
| 1994 | if (const ZExtInst *ZI = dyn_cast<ZExtInst>(V)) |
| 1995 | return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth, Q); |
| 1996 | |
| 1997 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) |
| 1998 | return isKnownToBeAPowerOfTwo(SI->getTrueValue(), OrZero, Depth, Q) && |
| 1999 | isKnownToBeAPowerOfTwo(SI->getFalseValue(), OrZero, Depth, Q); |
| 2000 | |
| 2001 | if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) { |
| 2002 | // A power of two and'd with anything is a power of two or zero. |
| 2003 | if (isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q) || |
| 2004 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, Depth, Q)) |
| 2005 | return true; |
| 2006 | // X & (-X) is always a power of two or zero. |
| 2007 | if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X)))) |
| 2008 | return true; |
| 2009 | return false; |
| 2010 | } |
| 2011 | |
| 2012 | // Adding a power-of-two or zero to the same power-of-two or zero yields |
| 2013 | // either the original power-of-two, a larger power-of-two or zero. |
| 2014 | if (match(V, m_Add(m_Value(X), m_Value(Y)))) { |
| 2015 | const OverflowingBinaryOperator *VOBO = cast<OverflowingBinaryOperator>(V); |
| 2016 | if (OrZero || Q.IIQ.hasNoUnsignedWrap(VOBO) || |
| 2017 | Q.IIQ.hasNoSignedWrap(VOBO)) { |
| 2018 | if (match(X, m_And(m_Specific(Y), m_Value())) || |
| 2019 | match(X, m_And(m_Value(), m_Specific(Y)))) |
| 2020 | if (isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q)) |
| 2021 | return true; |
| 2022 | if (match(Y, m_And(m_Specific(X), m_Value())) || |
| 2023 | match(Y, m_And(m_Value(), m_Specific(X)))) |
| 2024 | if (isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q)) |
| 2025 | return true; |
| 2026 | |
| 2027 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); |
| 2028 | KnownBits LHSBits(BitWidth); |
| 2029 | computeKnownBits(X, LHSBits, Depth, Q); |
| 2030 | |
| 2031 | KnownBits RHSBits(BitWidth); |
| 2032 | computeKnownBits(Y, RHSBits, Depth, Q); |
| 2033 | // If i8 V is a power of two or zero: |
| 2034 | // ZeroBits: 1 1 1 0 1 1 1 1 |
| 2035 | // ~ZeroBits: 0 0 0 1 0 0 0 0 |
| 2036 | if ((~(LHSBits.Zero & RHSBits.Zero)).isPowerOf2()) |
| 2037 | // If OrZero isn't set, we cannot give back a zero result. |
| 2038 | // Make sure either the LHS or RHS has a bit set. |
| 2039 | if (OrZero || RHSBits.One.getBoolValue() || LHSBits.One.getBoolValue()) |
| 2040 | return true; |
| 2041 | } |
| 2042 | } |
| 2043 | |
| 2044 | // An exact divide or right shift can only shift off zero bits, so the result |
| 2045 | // is a power of two only if the first operand is a power of two and not |
| 2046 | // copying a sign bit (sdiv int_min, 2). |
| 2047 | if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) || |
| 2048 | match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) { |
| 2049 | return isKnownToBeAPowerOfTwo(cast<Operator>(V)->getOperand(0), OrZero, |
| 2050 | Depth, Q); |
| 2051 | } |
| 2052 | |
| 2053 | return false; |
| 2054 | } |
| 2055 | |
| 2056 | /// Test whether a GEP's result is known to be non-null. |
| 2057 | /// |
| 2058 | /// Uses properties inherent in a GEP to try to determine whether it is known |
| 2059 | /// to be non-null. |
| 2060 | /// |
| 2061 | /// Currently this routine does not support vector GEPs. |
| 2062 | static bool isGEPKnownNonNull(const GEPOperator *GEP, unsigned Depth, |
| 2063 | const Query &Q) { |
| 2064 | const Function *F = nullptr; |
| 2065 | if (const Instruction *I = dyn_cast<Instruction>(GEP)) |
| 2066 | F = I->getFunction(); |
| 2067 | |
| 2068 | if (!GEP->isInBounds() || |
| 2069 | NullPointerIsDefined(F, GEP->getPointerAddressSpace())) |
| 2070 | return false; |
| 2071 | |
| 2072 | // FIXME: Support vector-GEPs. |
| 2073 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2073, __PRETTY_FUNCTION__)); |
| 2074 | |
| 2075 | // If the base pointer is non-null, we cannot walk to a null address with an |
| 2076 | // inbounds GEP in address space zero. |
| 2077 | if (isKnownNonZero(GEP->getPointerOperand(), Depth, Q)) |
| 2078 | return true; |
| 2079 | |
| 2080 | // Walk the GEP operands and see if any operand introduces a non-zero offset. |
| 2081 | // If so, then the GEP cannot produce a null pointer, as doing so would |
| 2082 | // inherently violate the inbounds contract within address space zero. |
| 2083 | for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP); |
| 2084 | GTI != GTE; ++GTI) { |
| 2085 | // Struct types are easy -- they must always be indexed by a constant. |
| 2086 | if (StructType *STy = GTI.getStructTypeOrNull()) { |
| 2087 | ConstantInt *OpC = cast<ConstantInt>(GTI.getOperand()); |
| 2088 | unsigned ElementIdx = OpC->getZExtValue(); |
| 2089 | const StructLayout *SL = Q.DL.getStructLayout(STy); |
| 2090 | uint64_t ElementOffset = SL->getElementOffset(ElementIdx); |
| 2091 | if (ElementOffset > 0) |
| 2092 | return true; |
| 2093 | continue; |
| 2094 | } |
| 2095 | |
| 2096 | // If we have a zero-sized type, the index doesn't matter. Keep looping. |
| 2097 | if (Q.DL.getTypeAllocSize(GTI.getIndexedType()).getKnownMinSize() == 0) |
| 2098 | continue; |
| 2099 | |
| 2100 | // Fast path the constant operand case both for efficiency and so we don't |
| 2101 | // increment Depth when just zipping down an all-constant GEP. |
| 2102 | if (ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand())) { |
| 2103 | if (!OpC->isZero()) |
| 2104 | return true; |
| 2105 | continue; |
| 2106 | } |
| 2107 | |
| 2108 | // We post-increment Depth here because while isKnownNonZero increments it |
| 2109 | // as well, when we pop back up that increment won't persist. We don't want |
| 2110 | // to recurse 10k times just because we have 10k GEP operands. We don't |
| 2111 | // bail completely out because we want to handle constant GEPs regardless |
| 2112 | // of depth. |
| 2113 | if (Depth++ >= MaxAnalysisRecursionDepth) |
| 2114 | continue; |
| 2115 | |
| 2116 | if (isKnownNonZero(GTI.getOperand(), Depth, Q)) |
| 2117 | return true; |
| 2118 | } |
| 2119 | |
| 2120 | return false; |
| 2121 | } |
| 2122 | |
| 2123 | static bool isKnownNonNullFromDominatingCondition(const Value *V, |
| 2124 | const Instruction *CtxI, |
| 2125 | const DominatorTree *DT) { |
| 2126 | if (isa<Constant>(V)) |
| 2127 | return false; |
| 2128 | |
| 2129 | if (!CtxI || !DT) |
| 2130 | return false; |
| 2131 | |
| 2132 | unsigned NumUsesExplored = 0; |
| 2133 | for (auto *U : V->users()) { |
| 2134 | // Avoid massive lists |
| 2135 | if (NumUsesExplored >= DomConditionsMaxUses) |
| 2136 | break; |
| 2137 | NumUsesExplored++; |
| 2138 | |
| 2139 | // If the value is used as an argument to a call or invoke, then argument |
| 2140 | // attributes may provide an answer about null-ness. |
| 2141 | if (const auto *CB = dyn_cast<CallBase>(U)) |
| 2142 | if (auto *CalledFunc = CB->getCalledFunction()) |
| 2143 | for (const Argument &Arg : CalledFunc->args()) |
| 2144 | if (CB->getArgOperand(Arg.getArgNo()) == V && |
| 2145 | Arg.hasNonNullAttr(/* AllowUndefOrPoison */ false) && |
| 2146 | DT->dominates(CB, CtxI)) |
| 2147 | return true; |
| 2148 | |
| 2149 | // If the value is used as a load/store, then the pointer must be non null. |
| 2150 | if (V == getLoadStorePointerOperand(U)) { |
| 2151 | const Instruction *I = cast<Instruction>(U); |
| 2152 | if (!NullPointerIsDefined(I->getFunction(), |
| 2153 | V->getType()->getPointerAddressSpace()) && |
| 2154 | DT->dominates(I, CtxI)) |
| 2155 | return true; |
| 2156 | } |
| 2157 | |
| 2158 | // Consider only compare instructions uniquely controlling a branch |
| 2159 | Value *RHS; |
| 2160 | CmpInst::Predicate Pred; |
| 2161 | if (!match(U, m_c_ICmp(Pred, m_Specific(V), m_Value(RHS)))) |
| 2162 | continue; |
| 2163 | |
| 2164 | bool NonNullIfTrue; |
| 2165 | if (cmpExcludesZero(Pred, RHS)) |
| 2166 | NonNullIfTrue = true; |
| 2167 | else if (cmpExcludesZero(CmpInst::getInversePredicate(Pred), RHS)) |
| 2168 | NonNullIfTrue = false; |
| 2169 | else |
| 2170 | continue; |
| 2171 | |
| 2172 | SmallVector<const User *, 4> WorkList; |
| 2173 | SmallPtrSet<const User *, 4> Visited; |
| 2174 | for (auto *CmpU : U->users()) { |
| 2175 | assert(WorkList.empty() && "Should be!")((WorkList.empty() && "Should be!") ? static_cast< void> (0) : __assert_fail ("WorkList.empty() && \"Should be!\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2175, __PRETTY_FUNCTION__)); |
| 2176 | if (Visited.insert(CmpU).second) |
| 2177 | WorkList.push_back(CmpU); |
| 2178 | |
| 2179 | while (!WorkList.empty()) { |
| 2180 | auto *Curr = WorkList.pop_back_val(); |
| 2181 | |
| 2182 | // If a user is an AND, add all its users to the work list. We only |
| 2183 | // propagate "pred != null" condition through AND because it is only |
| 2184 | // correct to assume that all conditions of AND are met in true branch. |
| 2185 | // TODO: Support similar logic of OR and EQ predicate? |
| 2186 | if (NonNullIfTrue) |
| 2187 | if (match(Curr, m_LogicalAnd(m_Value(), m_Value()))) { |
| 2188 | for (auto *CurrU : Curr->users()) |
| 2189 | if (Visited.insert(CurrU).second) |
| 2190 | WorkList.push_back(CurrU); |
| 2191 | continue; |
| 2192 | } |
| 2193 | |
| 2194 | if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) { |
| 2195 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2195, __PRETTY_FUNCTION__)); |
| 2196 | |
| 2197 | BasicBlock *NonNullSuccessor = |
| 2198 | BI->getSuccessor(NonNullIfTrue ? 0 : 1); |
| 2199 | BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor); |
| 2200 | if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent())) |
| 2201 | return true; |
| 2202 | } else if (NonNullIfTrue && isGuard(Curr) && |
| 2203 | DT->dominates(cast<Instruction>(Curr), CtxI)) { |
| 2204 | return true; |
| 2205 | } |
| 2206 | } |
| 2207 | } |
| 2208 | } |
| 2209 | |
| 2210 | return false; |
| 2211 | } |
| 2212 | |
| 2213 | /// Does the 'Range' metadata (which must be a valid MD_range operand list) |
| 2214 | /// ensure that the value it's attached to is never Value? 'RangeType' is |
| 2215 | /// is the type of the value described by the range. |
| 2216 | static bool rangeMetadataExcludesValue(const MDNode* Ranges, const APInt& Value) { |
| 2217 | const unsigned NumRanges = Ranges->getNumOperands() / 2; |
| 2218 | assert(NumRanges >= 1)((NumRanges >= 1) ? static_cast<void> (0) : __assert_fail ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2218, __PRETTY_FUNCTION__)); |
| 2219 | for (unsigned i = 0; i < NumRanges; ++i) { |
| 2220 | ConstantInt *Lower = |
| 2221 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 0)); |
| 2222 | ConstantInt *Upper = |
| 2223 | mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 1)); |
| 2224 | ConstantRange Range(Lower->getValue(), Upper->getValue()); |
| 2225 | if (Range.contains(Value)) |
| 2226 | return false; |
| 2227 | } |
| 2228 | return true; |
| 2229 | } |
| 2230 | |
| 2231 | /// Return true if the given value is known to be non-zero when defined. For |
| 2232 | /// vectors, return true if every demanded element is known to be non-zero when |
| 2233 | /// defined. For pointers, if the context instruction and dominator tree are |
| 2234 | /// specified, perform context-sensitive analysis and return true if the |
| 2235 | /// pointer couldn't possibly be null at the specified instruction. |
| 2236 | /// Supports values with integer or pointer type and vectors of integers. |
| 2237 | bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth, |
| 2238 | const Query &Q) { |
| 2239 | // FIXME: We currently have no way to represent the DemandedElts of a scalable |
| 2240 | // vector |
| 2241 | if (isa<ScalableVectorType>(V->getType())) |
| 2242 | return false; |
| 2243 | |
| 2244 | if (auto *C = dyn_cast<Constant>(V)) { |
| 2245 | if (C->isNullValue()) |
| 2246 | return false; |
| 2247 | if (isa<ConstantInt>(C)) |
| 2248 | // Must be non-zero due to null test above. |
| 2249 | return true; |
| 2250 | |
| 2251 | if (auto *CE = dyn_cast<ConstantExpr>(C)) { |
| 2252 | // See the comment for IntToPtr/PtrToInt instructions below. |
| 2253 | if (CE->getOpcode() == Instruction::IntToPtr || |
| 2254 | CE->getOpcode() == Instruction::PtrToInt) |
| 2255 | if (Q.DL.getTypeSizeInBits(CE->getOperand(0)->getType()) |
| 2256 | .getFixedSize() <= |
| 2257 | Q.DL.getTypeSizeInBits(CE->getType()).getFixedSize()) |
| 2258 | return isKnownNonZero(CE->getOperand(0), Depth, Q); |
| 2259 | } |
| 2260 | |
| 2261 | // For constant vectors, check that all elements are undefined or known |
| 2262 | // non-zero to determine that the whole vector is known non-zero. |
| 2263 | if (auto *VecTy = dyn_cast<FixedVectorType>(C->getType())) { |
| 2264 | for (unsigned i = 0, e = VecTy->getNumElements(); i != e; ++i) { |
| 2265 | if (!DemandedElts[i]) |
| 2266 | continue; |
| 2267 | Constant *Elt = C->getAggregateElement(i); |
| 2268 | if (!Elt || Elt->isNullValue()) |
| 2269 | return false; |
| 2270 | if (!isa<UndefValue>(Elt) && !isa<ConstantInt>(Elt)) |
| 2271 | return false; |
| 2272 | } |
| 2273 | return true; |
| 2274 | } |
| 2275 | |
| 2276 | // A global variable in address space 0 is non null unless extern weak |
| 2277 | // or an absolute symbol reference. Other address spaces may have null as a |
| 2278 | // valid address for a global, so we can't assume anything. |
| 2279 | if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) { |
| 2280 | if (!GV->isAbsoluteSymbolRef() && !GV->hasExternalWeakLinkage() && |
| 2281 | GV->getType()->getAddressSpace() == 0) |
| 2282 | return true; |
| 2283 | } else |
| 2284 | return false; |
| 2285 | } |
| 2286 | |
| 2287 | if (auto *I = dyn_cast<Instruction>(V)) { |
| 2288 | if (MDNode *Ranges = Q.IIQ.getMetadata(I, LLVMContext::MD_range)) { |
| 2289 | // If the possible ranges don't contain zero, then the value is |
| 2290 | // definitely non-zero. |
| 2291 | if (auto *Ty = dyn_cast<IntegerType>(V->getType())) { |
| 2292 | const APInt ZeroValue(Ty->getBitWidth(), 0); |
| 2293 | if (rangeMetadataExcludesValue(Ranges, ZeroValue)) |
| 2294 | return true; |
| 2295 | } |
| 2296 | } |
| 2297 | } |
| 2298 | |
| 2299 | if (isKnownNonZeroFromAssume(V, Q)) |
| 2300 | return true; |
| 2301 | |
| 2302 | // Some of the tests below are recursive, so bail out if we hit the limit. |
| 2303 | if (Depth++ >= MaxAnalysisRecursionDepth) |
| 2304 | return false; |
| 2305 | |
| 2306 | // Check for pointer simplifications. |
| 2307 | |
| 2308 | if (PointerType *PtrTy = dyn_cast<PointerType>(V->getType())) { |
| 2309 | // Alloca never returns null, malloc might. |
| 2310 | if (isa<AllocaInst>(V) && Q.DL.getAllocaAddrSpace() == 0) |
| 2311 | return true; |
| 2312 | |
| 2313 | // A byval, inalloca may not be null in a non-default addres space. A |
| 2314 | // nonnull argument is assumed never 0. |
| 2315 | if (const Argument *A = dyn_cast<Argument>(V)) { |
| 2316 | if (((A->hasPassPointeeByValueCopyAttr() && |
| 2317 | !NullPointerIsDefined(A->getParent(), PtrTy->getAddressSpace())) || |
| 2318 | A->hasNonNullAttr())) |
| 2319 | return true; |
| 2320 | } |
| 2321 | |
| 2322 | // A Load tagged with nonnull metadata is never null. |
| 2323 | if (const LoadInst *LI = dyn_cast<LoadInst>(V)) |
| 2324 | if (Q.IIQ.getMetadata(LI, LLVMContext::MD_nonnull)) |
| 2325 | return true; |
| 2326 | |
| 2327 | if (const auto *Call = dyn_cast<CallBase>(V)) { |
| 2328 | if (Call->isReturnNonNull()) |
| 2329 | return true; |
| 2330 | if (const auto *RP = getArgumentAliasingToReturnedPointer(Call, true)) |
| 2331 | return isKnownNonZero(RP, Depth, Q); |
| 2332 | } |
| 2333 | } |
| 2334 | |
| 2335 | if (isKnownNonNullFromDominatingCondition(V, Q.CxtI, Q.DT)) |
| 2336 | return true; |
| 2337 | |
| 2338 | // Check for recursive pointer simplifications. |
| 2339 | if (V->getType()->isPointerTy()) { |
| 2340 | // Look through bitcast operations, GEPs, and int2ptr instructions as they |
| 2341 | // do not alter the value, or at least not the nullness property of the |
| 2342 | // value, e.g., int2ptr is allowed to zero/sign extend the value. |
| 2343 | // |
| 2344 | // Note that we have to take special care to avoid looking through |
| 2345 | // truncating casts, e.g., int2ptr/ptr2int with appropriate sizes, as well |
| 2346 | // as casts that can alter the value, e.g., AddrSpaceCasts. |
| 2347 | if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) |
| 2348 | return isGEPKnownNonNull(GEP, Depth, Q); |
| 2349 | |
| 2350 | if (auto *BCO = dyn_cast<BitCastOperator>(V)) |
| 2351 | return isKnownNonZero(BCO->getOperand(0), Depth, Q); |
| 2352 | |
| 2353 | if (auto *I2P = dyn_cast<IntToPtrInst>(V)) |
| 2354 | if (Q.DL.getTypeSizeInBits(I2P->getSrcTy()).getFixedSize() <= |
| 2355 | Q.DL.getTypeSizeInBits(I2P->getDestTy()).getFixedSize()) |
| 2356 | return isKnownNonZero(I2P->getOperand(0), Depth, Q); |
| 2357 | } |
| 2358 | |
| 2359 | // Similar to int2ptr above, we can look through ptr2int here if the cast |
| 2360 | // is a no-op or an extend and not a truncate. |
| 2361 | if (auto *P2I = dyn_cast<PtrToIntInst>(V)) |
| 2362 | if (Q.DL.getTypeSizeInBits(P2I->getSrcTy()).getFixedSize() <= |
| 2363 | Q.DL.getTypeSizeInBits(P2I->getDestTy()).getFixedSize()) |
| 2364 | return isKnownNonZero(P2I->getOperand(0), Depth, Q); |
| 2365 | |
| 2366 | unsigned BitWidth = getBitWidth(V->getType()->getScalarType(), Q.DL); |
| 2367 | |
| 2368 | // X | Y != 0 if X != 0 or Y != 0. |
| 2369 | Value *X = nullptr, *Y = nullptr; |
| 2370 | if (match(V, m_Or(m_Value(X), m_Value(Y)))) |
| 2371 | return isKnownNonZero(X, DemandedElts, Depth, Q) || |
| 2372 | isKnownNonZero(Y, DemandedElts, Depth, Q); |
| 2373 | |
| 2374 | // ext X != 0 if X != 0. |
| 2375 | if (isa<SExtInst>(V) || isa<ZExtInst>(V)) |
| 2376 | return isKnownNonZero(cast<Instruction>(V)->getOperand(0), Depth, Q); |
| 2377 | |
| 2378 | // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined |
| 2379 | // if the lowest bit is shifted off the end. |
| 2380 | if (match(V, m_Shl(m_Value(X), m_Value(Y)))) { |
| 2381 | // shl nuw can't remove any non-zero bits. |
| 2382 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); |
| 2383 | if (Q.IIQ.hasNoUnsignedWrap(BO)) |
| 2384 | return isKnownNonZero(X, Depth, Q); |
| 2385 | |
| 2386 | KnownBits Known(BitWidth); |
| 2387 | computeKnownBits(X, DemandedElts, Known, Depth, Q); |
| 2388 | if (Known.One[0]) |
| 2389 | return true; |
| 2390 | } |
| 2391 | // shr X, Y != 0 if X is negative. Note that the value of the shift is not |
| 2392 | // defined if the sign bit is shifted off the end. |
| 2393 | else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) { |
| 2394 | // shr exact can only shift out zero bits. |
| 2395 | const PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V); |
| 2396 | if (BO->isExact()) |
| 2397 | return isKnownNonZero(X, Depth, Q); |
| 2398 | |
| 2399 | KnownBits Known = computeKnownBits(X, DemandedElts, Depth, Q); |
| 2400 | if (Known.isNegative()) |
| 2401 | return true; |
| 2402 | |
| 2403 | // If the shifter operand is a constant, and all of the bits shifted |
| 2404 | // out are known to be zero, and X is known non-zero then at least one |
| 2405 | // non-zero bit must remain. |
| 2406 | if (ConstantInt *Shift = dyn_cast<ConstantInt>(Y)) { |
| 2407 | auto ShiftVal = Shift->getLimitedValue(BitWidth - 1); |
| 2408 | // Is there a known one in the portion not shifted out? |
| 2409 | if (Known.countMaxLeadingZeros() < BitWidth - ShiftVal) |
| 2410 | return true; |
| 2411 | // Are all the bits to be shifted out known zero? |
| 2412 | if (Known.countMinTrailingZeros() >= ShiftVal) |
| 2413 | return isKnownNonZero(X, DemandedElts, Depth, Q); |
| 2414 | } |
| 2415 | } |
| 2416 | // div exact can only produce a zero if the dividend is zero. |
| 2417 | else if (match(V, m_Exact(m_IDiv(m_Value(X), m_Value())))) { |
| 2418 | return isKnownNonZero(X, DemandedElts, Depth, Q); |
| 2419 | } |
| 2420 | // X + Y. |
| 2421 | else if (match(V, m_Add(m_Value(X), m_Value(Y)))) { |
| 2422 | KnownBits XKnown = computeKnownBits(X, DemandedElts, Depth, Q); |
| 2423 | KnownBits YKnown = computeKnownBits(Y, DemandedElts, Depth, Q); |
| 2424 | |
| 2425 | // If X and Y are both non-negative (as signed values) then their sum is not |
| 2426 | // zero unless both X and Y are zero. |
| 2427 | if (XKnown.isNonNegative() && YKnown.isNonNegative()) |
| 2428 | if (isKnownNonZero(X, DemandedElts, Depth, Q) || |
| 2429 | isKnownNonZero(Y, DemandedElts, Depth, Q)) |
| 2430 | return true; |
| 2431 | |
| 2432 | // If X and Y are both negative (as signed values) then their sum is not |
| 2433 | // zero unless both X and Y equal INT_MIN. |
| 2434 | if (XKnown.isNegative() && YKnown.isNegative()) { |
| 2435 | APInt Mask = APInt::getSignedMaxValue(BitWidth); |
| 2436 | // The sign bit of X is set. If some other bit is set then X is not equal |
| 2437 | // to INT_MIN. |
| 2438 | if (XKnown.One.intersects(Mask)) |
| 2439 | return true; |
| 2440 | // The sign bit of Y is set. If some other bit is set then Y is not equal |
| 2441 | // to INT_MIN. |
| 2442 | if (YKnown.One.intersects(Mask)) |
| 2443 | return true; |
| 2444 | } |
| 2445 | |
| 2446 | // The sum of a non-negative number and a power of two is not zero. |
| 2447 | if (XKnown.isNonNegative() && |
| 2448 | isKnownToBeAPowerOfTwo(Y, /*OrZero*/ false, Depth, Q)) |
| 2449 | return true; |
| 2450 | if (YKnown.isNonNegative() && |
| 2451 | isKnownToBeAPowerOfTwo(X, /*OrZero*/ false, Depth, Q)) |
| 2452 | return true; |
| 2453 | } |
| 2454 | // X * Y. |
| 2455 | else if (match(V, m_Mul(m_Value(X), m_Value(Y)))) { |
| 2456 | const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V); |
| 2457 | // If X and Y are non-zero then so is X * Y as long as the multiplication |
| 2458 | // does not overflow. |
| 2459 | if ((Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO)) && |
| 2460 | isKnownNonZero(X, DemandedElts, Depth, Q) && |
| 2461 | isKnownNonZero(Y, DemandedElts, Depth, Q)) |
| 2462 | return true; |
| 2463 | } |
| 2464 | // (C ? X : Y) != 0 if X != 0 and Y != 0. |
| 2465 | else if (const SelectInst *SI = dyn_cast<SelectInst>(V)) { |
| 2466 | if (isKnownNonZero(SI->getTrueValue(), DemandedElts, Depth, Q) && |
| 2467 | isKnownNonZero(SI->getFalseValue(), DemandedElts, Depth, Q)) |
| 2468 | return true; |
| 2469 | } |
| 2470 | // PHI |
| 2471 | else if (const PHINode *PN = dyn_cast<PHINode>(V)) { |
| 2472 | // Try and detect a recurrence that monotonically increases from a |
| 2473 | // starting value, as these are common as induction variables. |
| 2474 | if (PN->getNumIncomingValues() == 2) { |
| 2475 | Value *Start = PN->getIncomingValue(0); |
| 2476 | Value *Induction = PN->getIncomingValue(1); |
| 2477 | if (isa<ConstantInt>(Induction) && !isa<ConstantInt>(Start)) |
| 2478 | std::swap(Start, Induction); |
| 2479 | if (ConstantInt *C = dyn_cast<ConstantInt>(Start)) { |
| 2480 | if (!C->isZero() && !C->isNegative()) { |
| 2481 | ConstantInt *X; |
| 2482 | if (Q.IIQ.UseInstrInfo && |
| 2483 | (match(Induction, m_NSWAdd(m_Specific(PN), m_ConstantInt(X))) || |
| 2484 | match(Induction, m_NUWAdd(m_Specific(PN), m_ConstantInt(X)))) && |
| 2485 | !X->isNegative()) |
| 2486 | return true; |
| 2487 | } |
| 2488 | } |
| 2489 | } |
| 2490 | // Check if all incoming values are non-zero using recursion. |
| 2491 | Query RecQ = Q; |
| 2492 | unsigned NewDepth = std::max(Depth, MaxAnalysisRecursionDepth - 1); |
| 2493 | return llvm::all_of(PN->operands(), [&](const Use &U) { |
| 2494 | if (U.get() == PN) |
| 2495 | return true; |
| 2496 | RecQ.CxtI = PN->getIncomingBlock(U)->getTerminator(); |
| 2497 | return isKnownNonZero(U.get(), DemandedElts, NewDepth, RecQ); |
| 2498 | }); |
| 2499 | } |
| 2500 | // ExtractElement |
| 2501 | else if (const auto *EEI = dyn_cast<ExtractElementInst>(V)) { |
| 2502 | const Value *Vec = EEI->getVectorOperand(); |
| 2503 | const Value *Idx = EEI->getIndexOperand(); |
| 2504 | auto *CIdx = dyn_cast<ConstantInt>(Idx); |
| 2505 | if (auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType())) { |
| 2506 | unsigned NumElts = VecTy->getNumElements(); |
| 2507 | APInt DemandedVecElts = APInt::getAllOnesValue(NumElts); |
| 2508 | if (CIdx && CIdx->getValue().ult(NumElts)) |
| 2509 | DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue()); |
| 2510 | return isKnownNonZero(Vec, DemandedVecElts, Depth, Q); |
| 2511 | } |
| 2512 | } |
| 2513 | // Freeze |
| 2514 | else if (const FreezeInst *FI = dyn_cast<FreezeInst>(V)) { |
| 2515 | auto *Op = FI->getOperand(0); |
| 2516 | if (isKnownNonZero(Op, Depth, Q) && |
| 2517 | isGuaranteedNotToBePoison(Op, Q.AC, Q.CxtI, Q.DT, Depth)) |
| 2518 | return true; |
| 2519 | } |
| 2520 | |
| 2521 | KnownBits Known(BitWidth); |
| 2522 | computeKnownBits(V, DemandedElts, Known, Depth, Q); |
| 2523 | return Known.One != 0; |
| 2524 | } |
| 2525 | |
| 2526 | bool isKnownNonZero(const Value* V, unsigned Depth, const Query& Q) { |
| 2527 | // FIXME: We currently have no way to represent the DemandedElts of a scalable |
| 2528 | // vector |
| 2529 | if (isa<ScalableVectorType>(V->getType())) |
| 2530 | return false; |
| 2531 | |
| 2532 | auto *FVTy = dyn_cast<FixedVectorType>(V->getType()); |
| 2533 | APInt DemandedElts = |
| 2534 | FVTy ? APInt::getAllOnesValue(FVTy->getNumElements()) : APInt(1, 1); |
| 2535 | return isKnownNonZero(V, DemandedElts, Depth, Q); |
| 2536 | } |
| 2537 | |
| 2538 | /// Return true if V2 == V1 + X, where X is known non-zero. |
| 2539 | static bool isAddOfNonZero(const Value *V1, const Value *V2, unsigned Depth, |
| 2540 | const Query &Q) { |
| 2541 | const BinaryOperator *BO = dyn_cast<BinaryOperator>(V1); |
| 2542 | if (!BO || BO->getOpcode() != Instruction::Add) |
| 2543 | return false; |
| 2544 | Value *Op = nullptr; |
| 2545 | if (V2 == BO->getOperand(0)) |
| 2546 | Op = BO->getOperand(1); |
| 2547 | else if (V2 == BO->getOperand(1)) |
| 2548 | Op = BO->getOperand(0); |
| 2549 | else |
| 2550 | return false; |
| 2551 | return isKnownNonZero(Op, Depth + 1, Q); |
| 2552 | } |
| 2553 | |
| 2554 | |
| 2555 | /// Return true if it is known that V1 != V2. |
| 2556 | static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth, |
| 2557 | const Query &Q) { |
| 2558 | if (V1 == V2) |
| 2559 | return false; |
| 2560 | if (V1->getType() != V2->getType()) |
| 2561 | // We can't look through casts yet. |
| 2562 | return false; |
| 2563 | |
| 2564 | if (Depth >= MaxAnalysisRecursionDepth) |
| 2565 | return false; |
| 2566 | |
| 2567 | // See if we can recurse through (exactly one of) our operands. This |
| 2568 | // requires our operation be 1-to-1 and map every input value to exactly |
| 2569 | // one output value. Such an operation is invertible. |
| 2570 | auto *O1 = dyn_cast<Operator>(V1); |
| 2571 | auto *O2 = dyn_cast<Operator>(V2); |
| 2572 | if (O1 && O2 && O1->getOpcode() == O2->getOpcode()) { |
| 2573 | switch (O1->getOpcode()) { |
| 2574 | default: break; |
| 2575 | case Instruction::Add: |
| 2576 | case Instruction::Sub: |
| 2577 | // Assume operand order has been canonicalized |
| 2578 | if (O1->getOperand(0) == O2->getOperand(0)) |
| 2579 | return isKnownNonEqual(O1->getOperand(1), O2->getOperand(1), |
| 2580 | Depth + 1, Q); |
| 2581 | if (O1->getOperand(1) == O2->getOperand(1)) |
| 2582 | return isKnownNonEqual(O1->getOperand(0), O2->getOperand(0), |
| 2583 | Depth + 1, Q); |
| 2584 | break; |
| 2585 | case Instruction::Mul: { |
| 2586 | // invertible if A * B == (A * B) mod 2^N where A, and B are integers |
| 2587 | // and N is the bitwdith. The nsw case is non-obvious, but proven by |
| 2588 | // alive2: https://alive2.llvm.org/ce/z/Z6D5qK |
| 2589 | auto *OBO1 = cast<OverflowingBinaryOperator>(O1); |
| 2590 | auto *OBO2 = cast<OverflowingBinaryOperator>(O2); |
| 2591 | if ((!OBO1->hasNoUnsignedWrap() || !OBO2->hasNoUnsignedWrap()) && |
| 2592 | (!OBO1->hasNoSignedWrap() || !OBO2->hasNoSignedWrap())) |
| 2593 | break; |
| 2594 | |
| 2595 | // Assume operand order has been canonicalized |
| 2596 | if (O1->getOperand(1) == O2->getOperand(1) && |
| 2597 | isa<ConstantInt>(O1->getOperand(1)) && |
| 2598 | !cast<ConstantInt>(O1->getOperand(1))->isZero()) |
| 2599 | return isKnownNonEqual(O1->getOperand(0), O2->getOperand(0), |
| 2600 | Depth + 1, Q); |
| 2601 | break; |
| 2602 | } |
| 2603 | case Instruction::SExt: |
| 2604 | case Instruction::ZExt: |
| 2605 | if (O1->getOperand(0)->getType() == O2->getOperand(0)->getType()) |
| 2606 | return isKnownNonEqual(O1->getOperand(0), O2->getOperand(0), |
| 2607 | Depth + 1, Q); |
| 2608 | break; |
| 2609 | }; |
| 2610 | } |
| 2611 | |
| 2612 | if (isAddOfNonZero(V1, V2, Depth, Q) || isAddOfNonZero(V2, V1, Depth, Q)) |
| 2613 | return true; |
| 2614 | |
| 2615 | if (V1->getType()->isIntOrIntVectorTy()) { |
| 2616 | // Are any known bits in V1 contradictory to known bits in V2? If V1 |
| 2617 | // has a known zero where V2 has a known one, they must not be equal. |
| 2618 | KnownBits Known1 = computeKnownBits(V1, Depth, Q); |
| 2619 | KnownBits Known2 = computeKnownBits(V2, Depth, Q); |
| 2620 | |
| 2621 | if (Known1.Zero.intersects(Known2.One) || |
| 2622 | Known2.Zero.intersects(Known1.One)) |
| 2623 | return true; |
| 2624 | } |
| 2625 | return false; |
| 2626 | } |
| 2627 | |
| 2628 | /// Return true if 'V & Mask' is known to be zero. We use this predicate to |
| 2629 | /// simplify operations downstream. Mask is known to be zero for bits that V |
| 2630 | /// cannot have. |
| 2631 | /// |
| 2632 | /// This function is defined on values with integer type, values with pointer |
| 2633 | /// type, and vectors of integers. In the case |
| 2634 | /// where V is a vector, the mask, known zero, and known one values are the |
| 2635 | /// same width as the vector element, and the bit is set only if it is true |
| 2636 | /// for all of the elements in the vector. |
| 2637 | bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth, |
| 2638 | const Query &Q) { |
| 2639 | KnownBits Known(Mask.getBitWidth()); |
| 2640 | computeKnownBits(V, Known, Depth, Q); |
| 2641 | return Mask.isSubsetOf(Known.Zero); |
| 2642 | } |
| 2643 | |
| 2644 | // Match a signed min+max clamp pattern like smax(smin(In, CHigh), CLow). |
| 2645 | // Returns the input and lower/upper bounds. |
| 2646 | static bool isSignedMinMaxClamp(const Value *Select, const Value *&In, |
| 2647 | const APInt *&CLow, const APInt *&CHigh) { |
| 2648 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2650, __PRETTY_FUNCTION__)) |
| 2649 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2650, __PRETTY_FUNCTION__)) |
| 2650 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2650, __PRETTY_FUNCTION__)); |
| 2651 | |
| 2652 | const Value *LHS = nullptr, *RHS = nullptr; |
| 2653 | SelectPatternFlavor SPF = matchSelectPattern(Select, LHS, RHS).Flavor; |
| 2654 | if (SPF != SPF_SMAX && SPF != SPF_SMIN) |
| 2655 | return false; |
| 2656 | |
| 2657 | if (!match(RHS, m_APInt(CLow))) |
| 2658 | return false; |
| 2659 | |
| 2660 | const Value *LHS2 = nullptr, *RHS2 = nullptr; |
| 2661 | SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor; |
| 2662 | if (getInverseMinMaxFlavor(SPF) != SPF2) |
| 2663 | return false; |
| 2664 | |
| 2665 | if (!match(RHS2, m_APInt(CHigh))) |
| 2666 | return false; |
| 2667 | |
| 2668 | if (SPF == SPF_SMIN) |
| 2669 | std::swap(CLow, CHigh); |
| 2670 | |
| 2671 | In = LHS2; |
| 2672 | return CLow->sle(*CHigh); |
| 2673 | } |
| 2674 | |
| 2675 | /// For vector constants, loop over the elements and find the constant with the |
| 2676 | /// minimum number of sign bits. Return 0 if the value is not a vector constant |
| 2677 | /// or if any element was not analyzed; otherwise, return the count for the |
| 2678 | /// element with the minimum number of sign bits. |
| 2679 | static unsigned computeNumSignBitsVectorConstant(const Value *V, |
| 2680 | const APInt &DemandedElts, |
| 2681 | unsigned TyBits) { |
| 2682 | const auto *CV = dyn_cast<Constant>(V); |
| 2683 | if (!CV || !isa<FixedVectorType>(CV->getType())) |
| 2684 | return 0; |
| 2685 | |
| 2686 | unsigned MinSignBits = TyBits; |
| 2687 | unsigned NumElts = cast<FixedVectorType>(CV->getType())->getNumElements(); |
| 2688 | for (unsigned i = 0; i != NumElts; ++i) { |
| 2689 | if (!DemandedElts[i]) |
| 2690 | continue; |
| 2691 | // If we find a non-ConstantInt, bail out. |
| 2692 | auto *Elt = dyn_cast_or_null<ConstantInt>(CV->getAggregateElement(i)); |
| 2693 | if (!Elt) |
| 2694 | return 0; |
| 2695 | |
| 2696 | MinSignBits = std::min(MinSignBits, Elt->getValue().getNumSignBits()); |
| 2697 | } |
| 2698 | |
| 2699 | return MinSignBits; |
| 2700 | } |
| 2701 | |
| 2702 | static unsigned ComputeNumSignBitsImpl(const Value *V, |
| 2703 | const APInt &DemandedElts, |
| 2704 | unsigned Depth, const Query &Q); |
| 2705 | |
| 2706 | static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts, |
| 2707 | unsigned Depth, const Query &Q) { |
| 2708 | unsigned Result = ComputeNumSignBitsImpl(V, DemandedElts, Depth, Q); |
| 2709 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2709, __PRETTY_FUNCTION__)); |
| 2710 | return Result; |
| 2711 | } |
| 2712 | |
| 2713 | /// Return the number of times the sign bit of the register is replicated into |
| 2714 | /// the other bits. We know that at least 1 bit is always equal to the sign bit |
| 2715 | /// (itself), but other cases can give us information. For example, immediately |
| 2716 | /// after an "ashr X, 2", we know that the top 3 bits are all equal to each |
| 2717 | /// other, so we return 3. For vectors, return the number of sign bits for the |
| 2718 | /// vector element with the minimum number of known sign bits of the demanded |
| 2719 | /// elements in the vector specified by DemandedElts. |
| 2720 | static unsigned ComputeNumSignBitsImpl(const Value *V, |
| 2721 | const APInt &DemandedElts, |
| 2722 | unsigned Depth, const Query &Q) { |
| 2723 | Type *Ty = V->getType(); |
| 2724 | |
| 2725 | // FIXME: We currently have no way to represent the DemandedElts of a scalable |
| 2726 | // vector |
| 2727 | if (isa<ScalableVectorType>(Ty)) |
| 2728 | return 1; |
| 2729 | |
| 2730 | #ifndef NDEBUG |
| 2731 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")((Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth" ) ? static_cast<void> (0) : __assert_fail ("Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2731, __PRETTY_FUNCTION__)); |
| 2732 | |
| 2733 | if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) { |
| 2734 | assert(((FVTy->getNumElements() == DemandedElts.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? static_cast<void> (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2736, __PRETTY_FUNCTION__)) |
| 2735 | FVTy->getNumElements() == DemandedElts.getBitWidth() &&((FVTy->getNumElements() == DemandedElts.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? static_cast<void> (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2736, __PRETTY_FUNCTION__)) |
| 2736 | "DemandedElt width should equal the fixed vector number of elements")((FVTy->getNumElements() == DemandedElts.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements" ) ? static_cast<void> (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2736, __PRETTY_FUNCTION__)); |
| 2737 | } else { |
| 2738 | assert(DemandedElts == APInt(1, 1) &&((DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars" ) ? static_cast<void> (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2739, __PRETTY_FUNCTION__)) |
| 2739 | "DemandedElt width should be 1 for scalars")((DemandedElts == APInt(1, 1) && "DemandedElt width should be 1 for scalars" ) ? static_cast<void> (0) : __assert_fail ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 2739, __PRETTY_FUNCTION__)); |
| 2740 | } |
| 2741 | #endif |
| 2742 | |
| 2743 | // We return the minimum number of sign bits that are guaranteed to be present |
| 2744 | // in V, so for undef we have to conservatively return 1. We don't have the |
| 2745 | // same behavior for poison though -- that's a FIXME today. |
| 2746 | |
| 2747 | Type *ScalarTy = Ty->getScalarType(); |
| 2748 | unsigned TyBits = ScalarTy->isPointerTy() ? |
| 2749 | Q.DL.getPointerTypeSizeInBits(ScalarTy) : |
| 2750 | Q.DL.getTypeSizeInBits(ScalarTy); |
| 2751 | |
| 2752 | unsigned Tmp, Tmp2; |
| 2753 | unsigned FirstAnswer = 1; |
| 2754 | |
| 2755 | // Note that ConstantInt is handled by the general computeKnownBits case |
| 2756 | // below. |
| 2757 | |
| 2758 | if (Depth == MaxAnalysisRecursionDepth) |
| 2759 | return 1; |
| 2760 | |
| 2761 | if (auto *U = dyn_cast<Operator>(V)) { |
| 2762 | switch (Operator::getOpcode(V)) { |
| 2763 | default: break; |
| 2764 | case Instruction::SExt: |
| 2765 | Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits(); |
| 2766 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q) + Tmp; |
| 2767 | |
| 2768 | case Instruction::SDiv: { |
| 2769 | const APInt *Denominator; |
| 2770 | // sdiv X, C -> adds log(C) sign bits. |
| 2771 | if (match(U->getOperand(1), m_APInt(Denominator))) { |
| 2772 | |
| 2773 | // Ignore non-positive denominator. |
| 2774 | if (!Denominator->isStrictlyPositive()) |
| 2775 | break; |
| 2776 | |
| 2777 | // Calculate the incoming numerator bits. |
| 2778 | unsigned NumBits = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2779 | |
| 2780 | // Add floor(log(C)) bits to the numerator bits. |
| 2781 | return std::min(TyBits, NumBits + Denominator->logBase2()); |
| 2782 | } |
| 2783 | break; |
| 2784 | } |
| 2785 | |
| 2786 | case Instruction::SRem: { |
| 2787 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2788 | |
| 2789 | const APInt *Denominator; |
| 2790 | // srem X, C -> we know that the result is within [-C+1,C) when C is a |
| 2791 | // positive constant. This let us put a lower bound on the number of sign |
| 2792 | // bits. |
| 2793 | if (match(U->getOperand(1), m_APInt(Denominator))) { |
| 2794 | |
| 2795 | // Ignore non-positive denominator. |
| 2796 | if (Denominator->isStrictlyPositive()) { |
| 2797 | // Calculate the leading sign bit constraints by examining the |
| 2798 | // denominator. Given that the denominator is positive, there are two |
| 2799 | // cases: |
| 2800 | // |
| 2801 | // 1. The numerator is positive. The result range is [0,C) and |
| 2802 | // [0,C) u< (1 << ceilLogBase2(C)). |
| 2803 | // |
| 2804 | // 2. The numerator is negative. Then the result range is (-C,0] and |
| 2805 | // integers in (-C,0] are either 0 or >u (-1 << ceilLogBase2(C)). |
| 2806 | // |
| 2807 | // Thus a lower bound on the number of sign bits is `TyBits - |
| 2808 | // ceilLogBase2(C)`. |
| 2809 | |
| 2810 | unsigned ResBits = TyBits - Denominator->ceilLogBase2(); |
| 2811 | Tmp = std::max(Tmp, ResBits); |
| 2812 | } |
| 2813 | } |
| 2814 | return Tmp; |
| 2815 | } |
| 2816 | |
| 2817 | case Instruction::AShr: { |
| 2818 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2819 | // ashr X, C -> adds C sign bits. Vectors too. |
| 2820 | const APInt *ShAmt; |
| 2821 | if (match(U->getOperand(1), m_APInt(ShAmt))) { |
| 2822 | if (ShAmt->uge(TyBits)) |
| 2823 | break; // Bad shift. |
| 2824 | unsigned ShAmtLimited = ShAmt->getZExtValue(); |
| 2825 | Tmp += ShAmtLimited; |
| 2826 | if (Tmp > TyBits) Tmp = TyBits; |
| 2827 | } |
| 2828 | return Tmp; |
| 2829 | } |
| 2830 | case Instruction::Shl: { |
| 2831 | const APInt *ShAmt; |
| 2832 | if (match(U->getOperand(1), m_APInt(ShAmt))) { |
| 2833 | // shl destroys sign bits. |
| 2834 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2835 | if (ShAmt->uge(TyBits) || // Bad shift. |
| 2836 | ShAmt->uge(Tmp)) break; // Shifted all sign bits out. |
| 2837 | Tmp2 = ShAmt->getZExtValue(); |
| 2838 | return Tmp - Tmp2; |
| 2839 | } |
| 2840 | break; |
| 2841 | } |
| 2842 | case Instruction::And: |
| 2843 | case Instruction::Or: |
| 2844 | case Instruction::Xor: // NOT is handled here. |
| 2845 | // Logical binary ops preserve the number of sign bits at the worst. |
| 2846 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2847 | if (Tmp != 1) { |
| 2848 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); |
| 2849 | FirstAnswer = std::min(Tmp, Tmp2); |
| 2850 | // We computed what we know about the sign bits as our first |
| 2851 | // answer. Now proceed to the generic code that uses |
| 2852 | // computeKnownBits, and pick whichever answer is better. |
| 2853 | } |
| 2854 | break; |
| 2855 | |
| 2856 | case Instruction::Select: { |
| 2857 | // If we have a clamp pattern, we know that the number of sign bits will |
| 2858 | // be the minimum of the clamp min/max range. |
| 2859 | const Value *X; |
| 2860 | const APInt *CLow, *CHigh; |
| 2861 | if (isSignedMinMaxClamp(U, X, CLow, CHigh)) |
| 2862 | return std::min(CLow->getNumSignBits(), CHigh->getNumSignBits()); |
| 2863 | |
| 2864 | Tmp = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); |
| 2865 | if (Tmp == 1) break; |
| 2866 | Tmp2 = ComputeNumSignBits(U->getOperand(2), Depth + 1, Q); |
| 2867 | return std::min(Tmp, Tmp2); |
| 2868 | } |
| 2869 | |
| 2870 | case Instruction::Add: |
| 2871 | // Add can have at most one carry bit. Thus we know that the output |
| 2872 | // is, at worst, one more bit than the inputs. |
| 2873 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2874 | if (Tmp == 1) break; |
| 2875 | |
| 2876 | // Special case decrementing a value (ADD X, -1): |
| 2877 | if (const auto *CRHS = dyn_cast<Constant>(U->getOperand(1))) |
| 2878 | if (CRHS->isAllOnesValue()) { |
| 2879 | KnownBits Known(TyBits); |
| 2880 | computeKnownBits(U->getOperand(0), Known, Depth + 1, Q); |
| 2881 | |
| 2882 | // If the input is known to be 0 or 1, the output is 0/-1, which is |
| 2883 | // all sign bits set. |
| 2884 | if ((Known.Zero | 1).isAllOnesValue()) |
| 2885 | return TyBits; |
| 2886 | |
| 2887 | // If we are subtracting one from a positive number, there is no carry |
| 2888 | // out of the result. |
| 2889 | if (Known.isNonNegative()) |
| 2890 | return Tmp; |
| 2891 | } |
| 2892 | |
| 2893 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); |
| 2894 | if (Tmp2 == 1) break; |
| 2895 | return std::min(Tmp, Tmp2) - 1; |
| 2896 | |
| 2897 | case Instruction::Sub: |
| 2898 | Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); |
| 2899 | if (Tmp2 == 1) break; |
| 2900 | |
| 2901 | // Handle NEG. |
| 2902 | if (const auto *CLHS = dyn_cast<Constant>(U->getOperand(0))) |
| 2903 | if (CLHS->isNullValue()) { |
| 2904 | KnownBits Known(TyBits); |
| 2905 | computeKnownBits(U->getOperand(1), Known, Depth + 1, Q); |
| 2906 | // If the input is known to be 0 or 1, the output is 0/-1, which is |
| 2907 | // all sign bits set. |
| 2908 | if ((Known.Zero | 1).isAllOnesValue()) |
| 2909 | return TyBits; |
| 2910 | |
| 2911 | // If the input is known to be positive (the sign bit is known clear), |
| 2912 | // the output of the NEG has the same number of sign bits as the |
| 2913 | // input. |
| 2914 | if (Known.isNonNegative()) |
| 2915 | return Tmp2; |
| 2916 | |
| 2917 | // Otherwise, we treat this like a SUB. |
| 2918 | } |
| 2919 | |
| 2920 | // Sub can have at most one carry bit. Thus we know that the output |
| 2921 | // is, at worst, one more bit than the inputs. |
| 2922 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2923 | if (Tmp == 1) break; |
| 2924 | return std::min(Tmp, Tmp2) - 1; |
| 2925 | |
| 2926 | case Instruction::Mul: { |
| 2927 | // The output of the Mul can be at most twice the valid bits in the |
| 2928 | // inputs. |
| 2929 | unsigned SignBitsOp0 = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2930 | if (SignBitsOp0 == 1) break; |
| 2931 | unsigned SignBitsOp1 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q); |
| 2932 | if (SignBitsOp1 == 1) break; |
| 2933 | unsigned OutValidBits = |
| 2934 | (TyBits - SignBitsOp0 + 1) + (TyBits - SignBitsOp1 + 1); |
| 2935 | return OutValidBits > TyBits ? 1 : TyBits - OutValidBits + 1; |
| 2936 | } |
| 2937 | |
| 2938 | case Instruction::PHI: { |
| 2939 | const PHINode *PN = cast<PHINode>(U); |
| 2940 | unsigned NumIncomingValues = PN->getNumIncomingValues(); |
| 2941 | // Don't analyze large in-degree PHIs. |
| 2942 | if (NumIncomingValues > 4) break; |
| 2943 | // Unreachable blocks may have zero-operand PHI nodes. |
| 2944 | if (NumIncomingValues == 0) break; |
| 2945 | |
| 2946 | // Take the minimum of all incoming values. This can't infinitely loop |
| 2947 | // because of our depth threshold. |
| 2948 | Query RecQ = Q; |
| 2949 | Tmp = TyBits; |
| 2950 | for (unsigned i = 0, e = NumIncomingValues; i != e; ++i) { |
| 2951 | if (Tmp == 1) return Tmp; |
| 2952 | RecQ.CxtI = PN->getIncomingBlock(i)->getTerminator(); |
| 2953 | Tmp = std::min( |
| 2954 | Tmp, ComputeNumSignBits(PN->getIncomingValue(i), Depth + 1, RecQ)); |
| 2955 | } |
| 2956 | return Tmp; |
| 2957 | } |
| 2958 | |
| 2959 | case Instruction::Trunc: |
| 2960 | // FIXME: it's tricky to do anything useful for this, but it is an |
| 2961 | // important case for targets like X86. |
| 2962 | break; |
| 2963 | |
| 2964 | case Instruction::ExtractElement: |
| 2965 | // Look through extract element. At the moment we keep this simple and |
| 2966 | // skip tracking the specific element. But at least we might find |
| 2967 | // information valid for all elements of the vector (for example if vector |
| 2968 | // is sign extended, shifted, etc). |
| 2969 | return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 2970 | |
| 2971 | case Instruction::ShuffleVector: { |
| 2972 | // Collect the minimum number of sign bits that are shared by every vector |
| 2973 | // element referenced by the shuffle. |
| 2974 | auto *Shuf = dyn_cast<ShuffleVectorInst>(U); |
| 2975 | if (!Shuf) { |
| 2976 | // FIXME: Add support for shufflevector constant expressions. |
| 2977 | return 1; |
| 2978 | } |
| 2979 | APInt DemandedLHS, DemandedRHS; |
| 2980 | // For undef elements, we don't know anything about the common state of |
| 2981 | // the shuffle result. |
| 2982 | if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) |
| 2983 | return 1; |
| 2984 | Tmp = std::numeric_limits<unsigned>::max(); |
| 2985 | if (!!DemandedLHS) { |
| 2986 | const Value *LHS = Shuf->getOperand(0); |
| 2987 | Tmp = ComputeNumSignBits(LHS, DemandedLHS, Depth + 1, Q); |
| 2988 | } |
| 2989 | // If we don't know anything, early out and try computeKnownBits |
| 2990 | // fall-back. |
| 2991 | if (Tmp == 1) |
| 2992 | break; |
| 2993 | if (!!DemandedRHS) { |
| 2994 | const Value *RHS = Shuf->getOperand(1); |
| 2995 | Tmp2 = ComputeNumSignBits(RHS, DemandedRHS, Depth + 1, Q); |
| 2996 | Tmp = std::min(Tmp, Tmp2); |
| 2997 | } |
| 2998 | // If we don't know anything, early out and try computeKnownBits |
| 2999 | // fall-back. |
| 3000 | if (Tmp == 1) |
| 3001 | break; |
| 3002 | assert(Tmp <= TyBits && "Failed to determine minimum sign bits")((Tmp <= TyBits && "Failed to determine minimum sign bits" ) ? static_cast<void> (0) : __assert_fail ("Tmp <= TyBits && \"Failed to determine minimum sign bits\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3002, __PRETTY_FUNCTION__)); |
| 3003 | return Tmp; |
| 3004 | } |
| 3005 | case Instruction::Call: { |
| 3006 | if (const auto *II = dyn_cast<IntrinsicInst>(U)) { |
| 3007 | switch (II->getIntrinsicID()) { |
| 3008 | default: break; |
| 3009 | case Intrinsic::abs: |
| 3010 | Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q); |
| 3011 | if (Tmp == 1) break; |
| 3012 | |
| 3013 | // Absolute value reduces number of sign bits by at most 1. |
| 3014 | return Tmp - 1; |
| 3015 | } |
| 3016 | } |
| 3017 | } |
| 3018 | } |
| 3019 | } |
| 3020 | |
| 3021 | // Finally, if we can prove that the top bits of the result are 0's or 1's, |
| 3022 | // use this information. |
| 3023 | |
| 3024 | // If we can examine all elements of a vector constant successfully, we're |
| 3025 | // done (we can't do any better than that). If not, keep trying. |
| 3026 | if (unsigned VecSignBits = |
| 3027 | computeNumSignBitsVectorConstant(V, DemandedElts, TyBits)) |
| 3028 | return VecSignBits; |
| 3029 | |
| 3030 | KnownBits Known(TyBits); |
| 3031 | computeKnownBits(V, DemandedElts, Known, Depth, Q); |
| 3032 | |
| 3033 | // If we know that the sign bit is either zero or one, determine the number of |
| 3034 | // identical bits in the top of the input value. |
| 3035 | return std::max(FirstAnswer, Known.countMinSignBits()); |
| 3036 | } |
| 3037 | |
| 3038 | /// This function computes the integer multiple of Base that equals V. |
| 3039 | /// If successful, it returns true and returns the multiple in |
| 3040 | /// Multiple. If unsuccessful, it returns false. It looks |
| 3041 | /// through SExt instructions only if LookThroughSExt is true. |
| 3042 | bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, |
| 3043 | bool LookThroughSExt, unsigned Depth) { |
| 3044 | assert(V && "No Value?")((V && "No Value?") ? static_cast<void> (0) : __assert_fail ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3044, __PRETTY_FUNCTION__)); |
| 3045 | assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")((Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth" ) ? static_cast<void> (0) : __assert_fail ("Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3045, __PRETTY_FUNCTION__)); |
| 3046 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3046, __PRETTY_FUNCTION__)); |
| 3047 | |
| 3048 | Type *T = V->getType(); |
| 3049 | |
| 3050 | ConstantInt *CI = dyn_cast<ConstantInt>(V); |
| 3051 | |
| 3052 | if (Base == 0) |
| 3053 | return false; |
| 3054 | |
| 3055 | if (Base == 1) { |
| 3056 | Multiple = V; |
| 3057 | return true; |
| 3058 | } |
| 3059 | |
| 3060 | ConstantExpr *CO = dyn_cast<ConstantExpr>(V); |
| 3061 | Constant *BaseVal = ConstantInt::get(T, Base); |
| 3062 | if (CO && CO == BaseVal) { |
| 3063 | // Multiple is 1. |
| 3064 | Multiple = ConstantInt::get(T, 1); |
| 3065 | return true; |
| 3066 | } |
| 3067 | |
| 3068 | if (CI && CI->getZExtValue() % Base == 0) { |
| 3069 | Multiple = ConstantInt::get(T, CI->getZExtValue() / Base); |
| 3070 | return true; |
| 3071 | } |
| 3072 | |
| 3073 | if (Depth == MaxAnalysisRecursionDepth) return false; |
| 3074 | |
| 3075 | Operator *I = dyn_cast<Operator>(V); |
| 3076 | if (!I) return false; |
| 3077 | |
| 3078 | switch (I->getOpcode()) { |
| 3079 | default: break; |
| 3080 | case Instruction::SExt: |
| 3081 | if (!LookThroughSExt) return false; |
| 3082 | // otherwise fall through to ZExt |
| 3083 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; |
| 3084 | case Instruction::ZExt: |
| 3085 | return ComputeMultiple(I->getOperand(0), Base, Multiple, |
| 3086 | LookThroughSExt, Depth+1); |
| 3087 | case Instruction::Shl: |
| 3088 | case Instruction::Mul: { |
| 3089 | Value *Op0 = I->getOperand(0); |
| 3090 | Value *Op1 = I->getOperand(1); |
| 3091 | |
| 3092 | if (I->getOpcode() == Instruction::Shl) { |
| 3093 | ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1); |
| 3094 | if (!Op1CI) return false; |
| 3095 | // Turn Op0 << Op1 into Op0 * 2^Op1 |
| 3096 | APInt Op1Int = Op1CI->getValue(); |
| 3097 | uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1); |
| 3098 | APInt API(Op1Int.getBitWidth(), 0); |
| 3099 | API.setBit(BitToSet); |
| 3100 | Op1 = ConstantInt::get(V->getContext(), API); |
| 3101 | } |
| 3102 | |
| 3103 | Value *Mul0 = nullptr; |
| 3104 | if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) { |
| 3105 | if (Constant *Op1C = dyn_cast<Constant>(Op1)) |
| 3106 | if (Constant *MulC = dyn_cast<Constant>(Mul0)) { |
| 3107 | if (Op1C->getType()->getPrimitiveSizeInBits().getFixedSize() < |
| 3108 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) |
| 3109 | Op1C = ConstantExpr::getZExt(Op1C, MulC->getType()); |
| 3110 | if (Op1C->getType()->getPrimitiveSizeInBits().getFixedSize() > |
| 3111 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) |
| 3112 | MulC = ConstantExpr::getZExt(MulC, Op1C->getType()); |
| 3113 | |
| 3114 | // V == Base * (Mul0 * Op1), so return (Mul0 * Op1) |
| 3115 | Multiple = ConstantExpr::getMul(MulC, Op1C); |
| 3116 | return true; |
| 3117 | } |
| 3118 | |
| 3119 | if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0)) |
| 3120 | if (Mul0CI->getValue() == 1) { |
| 3121 | // V == Base * Op1, so return Op1 |
| 3122 | Multiple = Op1; |
| 3123 | return true; |
| 3124 | } |
| 3125 | } |
| 3126 | |
| 3127 | Value *Mul1 = nullptr; |
| 3128 | if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) { |
| 3129 | if (Constant *Op0C = dyn_cast<Constant>(Op0)) |
| 3130 | if (Constant *MulC = dyn_cast<Constant>(Mul1)) { |
| 3131 | if (Op0C->getType()->getPrimitiveSizeInBits().getFixedSize() < |
| 3132 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) |
| 3133 | Op0C = ConstantExpr::getZExt(Op0C, MulC->getType()); |
| 3134 | if (Op0C->getType()->getPrimitiveSizeInBits().getFixedSize() > |
| 3135 | MulC->getType()->getPrimitiveSizeInBits().getFixedSize()) |
| 3136 | MulC = ConstantExpr::getZExt(MulC, Op0C->getType()); |
| 3137 | |
| 3138 | // V == Base * (Mul1 * Op0), so return (Mul1 * Op0) |
| 3139 | Multiple = ConstantExpr::getMul(MulC, Op0C); |
| 3140 | return true; |
| 3141 | } |
| 3142 | |
| 3143 | if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1)) |
| 3144 | if (Mul1CI->getValue() == 1) { |
| 3145 | // V == Base * Op0, so return Op0 |
| 3146 | Multiple = Op0; |
| 3147 | return true; |
| 3148 | } |
| 3149 | } |
| 3150 | } |
| 3151 | } |
| 3152 | |
| 3153 | // We could not determine if V is a multiple of Base. |
| 3154 | return false; |
| 3155 | } |
| 3156 | |
| 3157 | Intrinsic::ID llvm::getIntrinsicForCallSite(const CallBase &CB, |
| 3158 | const TargetLibraryInfo *TLI) { |
| 3159 | const Function *F = CB.getCalledFunction(); |
| 3160 | if (!F) |
| 3161 | return Intrinsic::not_intrinsic; |
| 3162 | |
| 3163 | if (F->isIntrinsic()) |
| 3164 | return F->getIntrinsicID(); |
| 3165 | |
| 3166 | // We are going to infer semantics of a library function based on mapping it |
| 3167 | // to an LLVM intrinsic. Check that the library function is available from |
| 3168 | // this callbase and in this environment. |
| 3169 | LibFunc Func; |
| 3170 | if (F->hasLocalLinkage() || !TLI || !TLI->getLibFunc(CB, Func) || |
| 3171 | !CB.onlyReadsMemory()) |
| 3172 | return Intrinsic::not_intrinsic; |
| 3173 | |
| 3174 | switch (Func) { |
| 3175 | default: |
| 3176 | break; |
| 3177 | case LibFunc_sin: |
| 3178 | case LibFunc_sinf: |
| 3179 | case LibFunc_sinl: |
| 3180 | return Intrinsic::sin; |
| 3181 | case LibFunc_cos: |
| 3182 | case LibFunc_cosf: |
| 3183 | case LibFunc_cosl: |
| 3184 | return Intrinsic::cos; |
| 3185 | case LibFunc_exp: |
| 3186 | case LibFunc_expf: |
| 3187 | case LibFunc_expl: |
| 3188 | return Intrinsic::exp; |
| 3189 | case LibFunc_exp2: |
| 3190 | case LibFunc_exp2f: |
| 3191 | case LibFunc_exp2l: |
| 3192 | return Intrinsic::exp2; |
| 3193 | case LibFunc_log: |
| 3194 | case LibFunc_logf: |
| 3195 | case LibFunc_logl: |
| 3196 | return Intrinsic::log; |
| 3197 | case LibFunc_log10: |
| 3198 | case LibFunc_log10f: |
| 3199 | case LibFunc_log10l: |
| 3200 | return Intrinsic::log10; |
| 3201 | case LibFunc_log2: |
| 3202 | case LibFunc_log2f: |
| 3203 | case LibFunc_log2l: |
| 3204 | return Intrinsic::log2; |
| 3205 | case LibFunc_fabs: |
| 3206 | case LibFunc_fabsf: |
| 3207 | case LibFunc_fabsl: |
| 3208 | return Intrinsic::fabs; |
| 3209 | case LibFunc_fmin: |
| 3210 | case LibFunc_fminf: |
| 3211 | case LibFunc_fminl: |
| 3212 | return Intrinsic::minnum; |
| 3213 | case LibFunc_fmax: |
| 3214 | case LibFunc_fmaxf: |
| 3215 | case LibFunc_fmaxl: |
| 3216 | return Intrinsic::maxnum; |
| 3217 | case LibFunc_copysign: |
| 3218 | case LibFunc_copysignf: |
| 3219 | case LibFunc_copysignl: |
| 3220 | return Intrinsic::copysign; |
| 3221 | case LibFunc_floor: |
| 3222 | case LibFunc_floorf: |
| 3223 | case LibFunc_floorl: |
| 3224 | return Intrinsic::floor; |
| 3225 | case LibFunc_ceil: |
| 3226 | case LibFunc_ceilf: |
| 3227 | case LibFunc_ceill: |
| 3228 | return Intrinsic::ceil; |
| 3229 | case LibFunc_trunc: |
| 3230 | case LibFunc_truncf: |
| 3231 | case LibFunc_truncl: |
| 3232 | return Intrinsic::trunc; |
| 3233 | case LibFunc_rint: |
| 3234 | case LibFunc_rintf: |
| 3235 | case LibFunc_rintl: |
| 3236 | return Intrinsic::rint; |
| 3237 | case LibFunc_nearbyint: |
| 3238 | case LibFunc_nearbyintf: |
| 3239 | case LibFunc_nearbyintl: |
| 3240 | return Intrinsic::nearbyint; |
| 3241 | case LibFunc_round: |
| 3242 | case LibFunc_roundf: |
| 3243 | case LibFunc_roundl: |
| 3244 | return Intrinsic::round; |
| 3245 | case LibFunc_roundeven: |
| 3246 | case LibFunc_roundevenf: |
| 3247 | case LibFunc_roundevenl: |
| 3248 | return Intrinsic::roundeven; |
| 3249 | case LibFunc_pow: |
| 3250 | case LibFunc_powf: |
| 3251 | case LibFunc_powl: |
| 3252 | return Intrinsic::pow; |
| 3253 | case LibFunc_sqrt: |
| 3254 | case LibFunc_sqrtf: |
| 3255 | case LibFunc_sqrtl: |
| 3256 | return Intrinsic::sqrt; |
| 3257 | } |
| 3258 | |
| 3259 | return Intrinsic::not_intrinsic; |
| 3260 | } |
| 3261 | |
| 3262 | /// Return true if we can prove that the specified FP value is never equal to |
| 3263 | /// -0.0. |
| 3264 | /// NOTE: Do not check 'nsz' here because that fast-math-flag does not guarantee |
| 3265 | /// that a value is not -0.0. It only guarantees that -0.0 may be treated |
| 3266 | /// the same as +0.0 in floating-point ops. |
| 3267 | /// |
| 3268 | /// NOTE: this function will need to be revisited when we support non-default |
| 3269 | /// rounding modes! |
| 3270 | bool llvm::CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI, |
| 3271 | unsigned Depth) { |
| 3272 | if (auto *CFP = dyn_cast<ConstantFP>(V)) |
| 3273 | return !CFP->getValueAPF().isNegZero(); |
| 3274 | |
| 3275 | if (Depth == MaxAnalysisRecursionDepth) |
| 3276 | return false; |
| 3277 | |
| 3278 | auto *Op = dyn_cast<Operator>(V); |
| 3279 | if (!Op) |
| 3280 | return false; |
| 3281 | |
| 3282 | // (fadd x, 0.0) is guaranteed to return +0.0, not -0.0. |
| 3283 | if (match(Op, m_FAdd(m_Value(), m_PosZeroFP()))) |
| 3284 | return true; |
| 3285 | |
| 3286 | // sitofp and uitofp turn into +0.0 for zero. |
| 3287 | if (isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) |
| 3288 | return true; |
| 3289 | |
| 3290 | if (auto *Call = dyn_cast<CallInst>(Op)) { |
| 3291 | Intrinsic::ID IID = getIntrinsicForCallSite(*Call, TLI); |
| 3292 | switch (IID) { |
| 3293 | default: |
| 3294 | break; |
| 3295 | // sqrt(-0.0) = -0.0, no other negative results are possible. |
| 3296 | case Intrinsic::sqrt: |
| 3297 | case Intrinsic::canonicalize: |
| 3298 | return CannotBeNegativeZero(Call->getArgOperand(0), TLI, Depth + 1); |
| 3299 | // fabs(x) != -0.0 |
| 3300 | case Intrinsic::fabs: |
| 3301 | return true; |
| 3302 | } |
| 3303 | } |
| 3304 | |
| 3305 | return false; |
| 3306 | } |
| 3307 | |
| 3308 | /// If \p SignBitOnly is true, test for a known 0 sign bit rather than a |
| 3309 | /// standard ordered compare. e.g. make -0.0 olt 0.0 be true because of the sign |
| 3310 | /// bit despite comparing equal. |
| 3311 | static bool cannotBeOrderedLessThanZeroImpl(const Value *V, |
| 3312 | const TargetLibraryInfo *TLI, |
| 3313 | bool SignBitOnly, |
| 3314 | unsigned Depth) { |
| 3315 | // TODO: This function does not do the right thing when SignBitOnly is true |
| 3316 | // and we're lowering to a hypothetical IEEE 754-compliant-but-evil platform |
| 3317 | // which flips the sign bits of NaNs. See |
| 3318 | // https://llvm.org/bugs/show_bug.cgi?id=31702. |
| 3319 | |
| 3320 | if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { |
| 3321 | return !CFP->getValueAPF().isNegative() || |
| 3322 | (!SignBitOnly && CFP->getValueAPF().isZero()); |
| 3323 | } |
| 3324 | |
| 3325 | // Handle vector of constants. |
| 3326 | if (auto *CV = dyn_cast<Constant>(V)) { |
| 3327 | if (auto *CVFVTy = dyn_cast<FixedVectorType>(CV->getType())) { |
| 3328 | unsigned NumElts = CVFVTy->getNumElements(); |
| 3329 | for (unsigned i = 0; i != NumElts; ++i) { |
| 3330 | auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i)); |
| 3331 | if (!CFP) |
| 3332 | return false; |
| 3333 | if (CFP->getValueAPF().isNegative() && |
| 3334 | (SignBitOnly || !CFP->getValueAPF().isZero())) |
| 3335 | return false; |
| 3336 | } |
| 3337 | |
| 3338 | // All non-negative ConstantFPs. |
| 3339 | return true; |
| 3340 | } |
| 3341 | } |
| 3342 | |
| 3343 | if (Depth == MaxAnalysisRecursionDepth) |
| 3344 | return false; |
| 3345 | |
| 3346 | const Operator *I = dyn_cast<Operator>(V); |
| 3347 | if (!I) |
| 3348 | return false; |
| 3349 | |
| 3350 | switch (I->getOpcode()) { |
| 3351 | default: |
| 3352 | break; |
| 3353 | // Unsigned integers are always nonnegative. |
| 3354 | case Instruction::UIToFP: |
| 3355 | return true; |
| 3356 | case Instruction::FMul: |
| 3357 | case Instruction::FDiv: |
| 3358 | // X * X is always non-negative or a NaN. |
| 3359 | // X / X is always exactly 1.0 or a NaN. |
| 3360 | if (I->getOperand(0) == I->getOperand(1) && |
| 3361 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs())) |
| 3362 | return true; |
| 3363 | |
| 3364 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; |
| 3365 | case Instruction::FAdd: |
| 3366 | case Instruction::FRem: |
| 3367 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, |
| 3368 | Depth + 1) && |
| 3369 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, |
| 3370 | Depth + 1); |
| 3371 | case Instruction::Select: |
| 3372 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, |
| 3373 | Depth + 1) && |
| 3374 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, |
| 3375 | Depth + 1); |
| 3376 | case Instruction::FPExt: |
| 3377 | case Instruction::FPTrunc: |
| 3378 | // Widening/narrowing never change sign. |
| 3379 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, |
| 3380 | Depth + 1); |
| 3381 | case Instruction::ExtractElement: |
| 3382 | // Look through extract element. At the moment we keep this simple and skip |
| 3383 | // tracking the specific element. But at least we might find information |
| 3384 | // valid for all elements of the vector. |
| 3385 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, |
| 3386 | Depth + 1); |
| 3387 | case Instruction::Call: |
| 3388 | const auto *CI = cast<CallInst>(I); |
| 3389 | Intrinsic::ID IID = getIntrinsicForCallSite(*CI, TLI); |
| 3390 | switch (IID) { |
| 3391 | default: |
| 3392 | break; |
| 3393 | case Intrinsic::maxnum: { |
| 3394 | Value *V0 = I->getOperand(0), *V1 = I->getOperand(1); |
| 3395 | auto isPositiveNum = [&](Value *V) { |
| 3396 | if (SignBitOnly) { |
| 3397 | // With SignBitOnly, this is tricky because the result of |
| 3398 | // maxnum(+0.0, -0.0) is unspecified. Just check if the operand is |
| 3399 | // a constant strictly greater than 0.0. |
| 3400 | const APFloat *C; |
| 3401 | return match(V, m_APFloat(C)) && |
| 3402 | *C > APFloat::getZero(C->getSemantics()); |
| 3403 | } |
| 3404 | |
| 3405 | // -0.0 compares equal to 0.0, so if this operand is at least -0.0, |
| 3406 | // maxnum can't be ordered-less-than-zero. |
| 3407 | return isKnownNeverNaN(V, TLI) && |
| 3408 | cannotBeOrderedLessThanZeroImpl(V, TLI, false, Depth + 1); |
| 3409 | }; |
| 3410 | |
| 3411 | // TODO: This could be improved. We could also check that neither operand |
| 3412 | // has its sign bit set (and at least 1 is not-NAN?). |
| 3413 | return isPositiveNum(V0) || isPositiveNum(V1); |
| 3414 | } |
| 3415 | |
| 3416 | case Intrinsic::maximum: |
| 3417 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, |
| 3418 | Depth + 1) || |
| 3419 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, |
| 3420 | Depth + 1); |
| 3421 | case Intrinsic::minnum: |
| 3422 | case Intrinsic::minimum: |
| 3423 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, |
| 3424 | Depth + 1) && |
| 3425 | cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly, |
| 3426 | Depth + 1); |
| 3427 | case Intrinsic::exp: |
| 3428 | case Intrinsic::exp2: |
| 3429 | case Intrinsic::fabs: |
| 3430 | return true; |
| 3431 | |
| 3432 | case Intrinsic::sqrt: |
| 3433 | // sqrt(x) is always >= -0 or NaN. Moreover, sqrt(x) == -0 iff x == -0. |
| 3434 | if (!SignBitOnly) |
| 3435 | return true; |
| 3436 | return CI->hasNoNaNs() && (CI->hasNoSignedZeros() || |
| 3437 | CannotBeNegativeZero(CI->getOperand(0), TLI)); |
| 3438 | |
| 3439 | case Intrinsic::powi: |
| 3440 | if (ConstantInt *Exponent = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| 3441 | // powi(x,n) is non-negative if n is even. |
| 3442 | if (Exponent->getBitWidth() <= 64 && Exponent->getSExtValue() % 2u == 0) |
| 3443 | return true; |
| 3444 | } |
| 3445 | // TODO: This is not correct. Given that exp is an integer, here are the |
| 3446 | // ways that pow can return a negative value: |
| 3447 | // |
| 3448 | // pow(x, exp) --> negative if exp is odd and x is negative. |
| 3449 | // pow(-0, exp) --> -inf if exp is negative odd. |
| 3450 | // pow(-0, exp) --> -0 if exp is positive odd. |
| 3451 | // pow(-inf, exp) --> -0 if exp is negative odd. |
| 3452 | // pow(-inf, exp) --> -inf if exp is positive odd. |
| 3453 | // |
| 3454 | // Therefore, if !SignBitOnly, we can return true if x >= +0 or x is NaN, |
| 3455 | // but we must return false if x == -0. Unfortunately we do not currently |
| 3456 | // have a way of expressing this constraint. See details in |
| 3457 | // https://llvm.org/bugs/show_bug.cgi?id=31702. |
| 3458 | return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly, |
| 3459 | Depth + 1); |
| 3460 | |
| 3461 | case Intrinsic::fma: |
| 3462 | case Intrinsic::fmuladd: |
| 3463 | // x*x+y is non-negative if y is non-negative. |
| 3464 | return I->getOperand(0) == I->getOperand(1) && |
| 3465 | (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()) && |
| 3466 | cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly, |
| 3467 | Depth + 1); |
| 3468 | } |
| 3469 | break; |
| 3470 | } |
| 3471 | return false; |
| 3472 | } |
| 3473 | |
| 3474 | bool llvm::CannotBeOrderedLessThanZero(const Value *V, |
| 3475 | const TargetLibraryInfo *TLI) { |
| 3476 | return cannotBeOrderedLessThanZeroImpl(V, TLI, false, 0); |
| 3477 | } |
| 3478 | |
| 3479 | bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) { |
| 3480 | return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0); |
| 3481 | } |
| 3482 | |
| 3483 | bool llvm::isKnownNeverInfinity(const Value *V, const TargetLibraryInfo *TLI, |
| 3484 | unsigned Depth) { |
| 3485 | assert(V->getType()->isFPOrFPVectorTy() && "Querying for Inf on non-FP type")((V->getType()->isFPOrFPVectorTy() && "Querying for Inf on non-FP type" ) ? static_cast<void> (0) : __assert_fail ("V->getType()->isFPOrFPVectorTy() && \"Querying for Inf on non-FP type\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3485, __PRETTY_FUNCTION__)); |
| 3486 | |
| 3487 | // If we're told that infinities won't happen, assume they won't. |
| 3488 | if (auto *FPMathOp = dyn_cast<FPMathOperator>(V)) |
| 3489 | if (FPMathOp->hasNoInfs()) |
| 3490 | return true; |
| 3491 | |
| 3492 | // Handle scalar constants. |
| 3493 | if (auto *CFP = dyn_cast<ConstantFP>(V)) |
| 3494 | return !CFP->isInfinity(); |
| 3495 | |
| 3496 | if (Depth == MaxAnalysisRecursionDepth) |
| 3497 | return false; |
| 3498 | |
| 3499 | if (auto *Inst = dyn_cast<Instruction>(V)) { |
| 3500 | switch (Inst->getOpcode()) { |
| 3501 | case Instruction::Select: { |
| 3502 | return isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1) && |
| 3503 | isKnownNeverInfinity(Inst->getOperand(2), TLI, Depth + 1); |
| 3504 | } |
| 3505 | case Instruction::SIToFP: |
| 3506 | case Instruction::UIToFP: { |
| 3507 | // Get width of largest magnitude integer (remove a bit if signed). |
| 3508 | // This still works for a signed minimum value because the largest FP |
| 3509 | // value is scaled by some fraction close to 2.0 (1.0 + 0.xxxx). |
| 3510 | int IntSize = Inst->getOperand(0)->getType()->getScalarSizeInBits(); |
| 3511 | if (Inst->getOpcode() == Instruction::SIToFP) |
| 3512 | --IntSize; |
| 3513 | |
| 3514 | // If the exponent of the largest finite FP value can hold the largest |
| 3515 | // integer, the result of the cast must be finite. |
| 3516 | Type *FPTy = Inst->getType()->getScalarType(); |
| 3517 | return ilogb(APFloat::getLargest(FPTy->getFltSemantics())) >= IntSize; |
| 3518 | } |
| 3519 | default: |
| 3520 | break; |
| 3521 | } |
| 3522 | } |
| 3523 | |
| 3524 | // try to handle fixed width vector constants |
| 3525 | auto *VFVTy = dyn_cast<FixedVectorType>(V->getType()); |
| 3526 | if (VFVTy && isa<Constant>(V)) { |
| 3527 | // For vectors, verify that each element is not infinity. |
| 3528 | unsigned NumElts = VFVTy->getNumElements(); |
| 3529 | for (unsigned i = 0; i != NumElts; ++i) { |
| 3530 | Constant *Elt = cast<Constant>(V)->getAggregateElement(i); |
| 3531 | if (!Elt) |
| 3532 | return false; |
| 3533 | if (isa<UndefValue>(Elt)) |
| 3534 | continue; |
| 3535 | auto *CElt = dyn_cast<ConstantFP>(Elt); |
| 3536 | if (!CElt || CElt->isInfinity()) |
| 3537 | return false; |
| 3538 | } |
| 3539 | // All elements were confirmed non-infinity or undefined. |
| 3540 | return true; |
| 3541 | } |
| 3542 | |
| 3543 | // was not able to prove that V never contains infinity |
| 3544 | return false; |
| 3545 | } |
| 3546 | |
| 3547 | bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI, |
| 3548 | unsigned Depth) { |
| 3549 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3549, __PRETTY_FUNCTION__)); |
| 3550 | |
| 3551 | // If we're told that NaNs won't happen, assume they won't. |
| 3552 | if (auto *FPMathOp = dyn_cast<FPMathOperator>(V)) |
| 3553 | if (FPMathOp->hasNoNaNs()) |
| 3554 | return true; |
| 3555 | |
| 3556 | // Handle scalar constants. |
| 3557 | if (auto *CFP = dyn_cast<ConstantFP>(V)) |
| 3558 | return !CFP->isNaN(); |
| 3559 | |
| 3560 | if (Depth == MaxAnalysisRecursionDepth) |
| 3561 | return false; |
| 3562 | |
| 3563 | if (auto *Inst = dyn_cast<Instruction>(V)) { |
| 3564 | switch (Inst->getOpcode()) { |
| 3565 | case Instruction::FAdd: |
| 3566 | case Instruction::FSub: |
| 3567 | // Adding positive and negative infinity produces NaN. |
| 3568 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) && |
| 3569 | isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && |
| 3570 | (isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) || |
| 3571 | isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1)); |
| 3572 | |
| 3573 | case Instruction::FMul: |
| 3574 | // Zero multiplied with infinity produces NaN. |
| 3575 | // FIXME: If neither side can be zero fmul never produces NaN. |
| 3576 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) && |
| 3577 | isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) && |
| 3578 | isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && |
| 3579 | isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1); |
| 3580 | |
| 3581 | case Instruction::FDiv: |
| 3582 | case Instruction::FRem: |
| 3583 | // FIXME: Only 0/0, Inf/Inf, Inf REM x and x REM 0 produce NaN. |
| 3584 | return false; |
| 3585 | |
| 3586 | case Instruction::Select: { |
| 3587 | return isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) && |
| 3588 | isKnownNeverNaN(Inst->getOperand(2), TLI, Depth + 1); |
| 3589 | } |
| 3590 | case Instruction::SIToFP: |
| 3591 | case Instruction::UIToFP: |
| 3592 | return true; |
| 3593 | case Instruction::FPTrunc: |
| 3594 | case Instruction::FPExt: |
| 3595 | return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1); |
| 3596 | default: |
| 3597 | break; |
| 3598 | } |
| 3599 | } |
| 3600 | |
| 3601 | if (const auto *II = dyn_cast<IntrinsicInst>(V)) { |
| 3602 | switch (II->getIntrinsicID()) { |
| 3603 | case Intrinsic::canonicalize: |
| 3604 | case Intrinsic::fabs: |
| 3605 | case Intrinsic::copysign: |
| 3606 | case Intrinsic::exp: |
| 3607 | case Intrinsic::exp2: |
| 3608 | case Intrinsic::floor: |
| 3609 | case Intrinsic::ceil: |
| 3610 | case Intrinsic::trunc: |
| 3611 | case Intrinsic::rint: |
| 3612 | case Intrinsic::nearbyint: |
| 3613 | case Intrinsic::round: |
| 3614 | case Intrinsic::roundeven: |
| 3615 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1); |
| 3616 | case Intrinsic::sqrt: |
| 3617 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) && |
| 3618 | CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI); |
| 3619 | case Intrinsic::minnum: |
| 3620 | case Intrinsic::maxnum: |
| 3621 | // If either operand is not NaN, the result is not NaN. |
| 3622 | return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) || |
| 3623 | isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1); |
| 3624 | default: |
| 3625 | return false; |
| 3626 | } |
| 3627 | } |
| 3628 | |
| 3629 | // Try to handle fixed width vector constants |
| 3630 | auto *VFVTy = dyn_cast<FixedVectorType>(V->getType()); |
| 3631 | if (VFVTy && isa<Constant>(V)) { |
| 3632 | // For vectors, verify that each element is not NaN. |
| 3633 | unsigned NumElts = VFVTy->getNumElements(); |
| 3634 | for (unsigned i = 0; i != NumElts; ++i) { |
| 3635 | Constant *Elt = cast<Constant>(V)->getAggregateElement(i); |
| 3636 | if (!Elt) |
| 3637 | return false; |
| 3638 | if (isa<UndefValue>(Elt)) |
| 3639 | continue; |
| 3640 | auto *CElt = dyn_cast<ConstantFP>(Elt); |
| 3641 | if (!CElt || CElt->isNaN()) |
| 3642 | return false; |
| 3643 | } |
| 3644 | // All elements were confirmed not-NaN or undefined. |
| 3645 | return true; |
| 3646 | } |
| 3647 | |
| 3648 | // Was not able to prove that V never contains NaN |
| 3649 | return false; |
| 3650 | } |
| 3651 | |
| 3652 | Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) { |
| 3653 | |
| 3654 | // All byte-wide stores are splatable, even of arbitrary variables. |
| 3655 | if (V->getType()->isIntegerTy(8)) |
| 3656 | return V; |
| 3657 | |
| 3658 | LLVMContext &Ctx = V->getContext(); |
| 3659 | |
| 3660 | // Undef don't care. |
| 3661 | auto *UndefInt8 = UndefValue::get(Type::getInt8Ty(Ctx)); |
| 3662 | if (isa<UndefValue>(V)) |
| 3663 | return UndefInt8; |
| 3664 | |
| 3665 | // Return Undef for zero-sized type. |
| 3666 | if (!DL.getTypeStoreSize(V->getType()).isNonZero()) |
| 3667 | return UndefInt8; |
| 3668 | |
| 3669 | Constant *C = dyn_cast<Constant>(V); |
| 3670 | if (!C) { |
| 3671 | // Conceptually, we could handle things like: |
| 3672 | // %a = zext i8 %X to i16 |
| 3673 | // %b = shl i16 %a, 8 |
| 3674 | // %c = or i16 %a, %b |
| 3675 | // but until there is an example that actually needs this, it doesn't seem |
| 3676 | // worth worrying about. |
| 3677 | return nullptr; |
| 3678 | } |
| 3679 | |
| 3680 | // Handle 'null' ConstantArrayZero etc. |
| 3681 | if (C->isNullValue()) |
| 3682 | return Constant::getNullValue(Type::getInt8Ty(Ctx)); |
| 3683 | |
| 3684 | // Constant floating-point values can be handled as integer values if the |
| 3685 | // corresponding integer value is "byteable". An important case is 0.0. |
| 3686 | if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) { |
| 3687 | Type *Ty = nullptr; |
| 3688 | if (CFP->getType()->isHalfTy()) |
| 3689 | Ty = Type::getInt16Ty(Ctx); |
| 3690 | else if (CFP->getType()->isFloatTy()) |
| 3691 | Ty = Type::getInt32Ty(Ctx); |
| 3692 | else if (CFP->getType()->isDoubleTy()) |
| 3693 | Ty = Type::getInt64Ty(Ctx); |
| 3694 | // Don't handle long double formats, which have strange constraints. |
| 3695 | return Ty ? isBytewiseValue(ConstantExpr::getBitCast(CFP, Ty), DL) |
| 3696 | : nullptr; |
| 3697 | } |
| 3698 | |
| 3699 | // We can handle constant integers that are multiple of 8 bits. |
| 3700 | if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) { |
| 3701 | if (CI->getBitWidth() % 8 == 0) { |
| 3702 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3702, __PRETTY_FUNCTION__)); |
| 3703 | if (!CI->getValue().isSplat(8)) |
| 3704 | return nullptr; |
| 3705 | return ConstantInt::get(Ctx, CI->getValue().trunc(8)); |
| 3706 | } |
| 3707 | } |
| 3708 | |
| 3709 | if (auto *CE = dyn_cast<ConstantExpr>(C)) { |
| 3710 | if (CE->getOpcode() == Instruction::IntToPtr) { |
| 3711 | if (auto *PtrTy = dyn_cast<PointerType>(CE->getType())) { |
| 3712 | unsigned BitWidth = DL.getPointerSizeInBits(PtrTy->getAddressSpace()); |
| 3713 | return isBytewiseValue( |
| 3714 | ConstantExpr::getIntegerCast(CE->getOperand(0), |
| 3715 | Type::getIntNTy(Ctx, BitWidth), false), |
| 3716 | DL); |
| 3717 | } |
| 3718 | } |
| 3719 | } |
| 3720 | |
| 3721 | auto Merge = [&](Value *LHS, Value *RHS) -> Value * { |
| 3722 | if (LHS == RHS) |
| 3723 | return LHS; |
| 3724 | if (!LHS || !RHS) |
| 3725 | return nullptr; |
| 3726 | if (LHS == UndefInt8) |
| 3727 | return RHS; |
| 3728 | if (RHS == UndefInt8) |
| 3729 | return LHS; |
| 3730 | return nullptr; |
| 3731 | }; |
| 3732 | |
| 3733 | if (ConstantDataSequential *CA = dyn_cast<ConstantDataSequential>(C)) { |
| 3734 | Value *Val = UndefInt8; |
| 3735 | for (unsigned I = 0, E = CA->getNumElements(); I != E; ++I) |
| 3736 | if (!(Val = Merge(Val, isBytewiseValue(CA->getElementAsConstant(I), DL)))) |
| 3737 | return nullptr; |
| 3738 | return Val; |
| 3739 | } |
| 3740 | |
| 3741 | if (isa<ConstantAggregate>(C)) { |
| 3742 | Value *Val = UndefInt8; |
| 3743 | for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) |
| 3744 | if (!(Val = Merge(Val, isBytewiseValue(C->getOperand(I), DL)))) |
| 3745 | return nullptr; |
| 3746 | return Val; |
| 3747 | } |
| 3748 | |
| 3749 | // Don't try to handle the handful of other constants. |
| 3750 | return nullptr; |
| 3751 | } |
| 3752 | |
| 3753 | // This is the recursive version of BuildSubAggregate. It takes a few different |
| 3754 | // arguments. Idxs is the index within the nested struct From that we are |
| 3755 | // looking at now (which is of type IndexedType). IdxSkip is the number of |
| 3756 | // indices from Idxs that should be left out when inserting into the resulting |
| 3757 | // struct. To is the result struct built so far, new insertvalue instructions |
| 3758 | // build on that. |
| 3759 | static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType, |
| 3760 | SmallVectorImpl<unsigned> &Idxs, |
| 3761 | unsigned IdxSkip, |
| 3762 | Instruction *InsertBefore) { |
| 3763 | StructType *STy = dyn_cast<StructType>(IndexedType); |
| 3764 | if (STy) { |
| 3765 | // Save the original To argument so we can modify it |
| 3766 | Value *OrigTo = To; |
| 3767 | // General case, the type indexed by Idxs is a struct |
| 3768 | for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { |
| 3769 | // Process each struct element recursively |
| 3770 | Idxs.push_back(i); |
| 3771 | Value *PrevTo = To; |
| 3772 | To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, |
| 3773 | InsertBefore); |
| 3774 | Idxs.pop_back(); |
| 3775 | if (!To) { |
| 3776 | // Couldn't find any inserted value for this index? Cleanup |
| 3777 | while (PrevTo != OrigTo) { |
| 3778 | InsertValueInst* Del = cast<InsertValueInst>(PrevTo); |
| 3779 | PrevTo = Del->getAggregateOperand(); |
| 3780 | Del->eraseFromParent(); |
| 3781 | } |
| 3782 | // Stop processing elements |
| 3783 | break; |
| 3784 | } |
| 3785 | } |
| 3786 | // If we successfully found a value for each of our subaggregates |
| 3787 | if (To) |
| 3788 | return To; |
| 3789 | } |
| 3790 | // Base case, the type indexed by SourceIdxs is not a struct, or not all of |
| 3791 | // the struct's elements had a value that was inserted directly. In the latter |
| 3792 | // case, perhaps we can't determine each of the subelements individually, but |
| 3793 | // we might be able to find the complete struct somewhere. |
| 3794 | |
| 3795 | // Find the value that is at that particular spot |
| 3796 | Value *V = FindInsertedValue(From, Idxs); |
| 3797 | |
| 3798 | if (!V) |
| 3799 | return nullptr; |
| 3800 | |
| 3801 | // Insert the value in the new (sub) aggregate |
| 3802 | return InsertValueInst::Create(To, V, makeArrayRef(Idxs).slice(IdxSkip), |
| 3803 | "tmp", InsertBefore); |
| 3804 | } |
| 3805 | |
| 3806 | // This helper takes a nested struct and extracts a part of it (which is again a |
| 3807 | // struct) into a new value. For example, given the struct: |
| 3808 | // { a, { b, { c, d }, e } } |
| 3809 | // and the indices "1, 1" this returns |
| 3810 | // { c, d }. |
| 3811 | // |
| 3812 | // It does this by inserting an insertvalue for each element in the resulting |
| 3813 | // struct, as opposed to just inserting a single struct. This will only work if |
| 3814 | // each of the elements of the substruct are known (ie, inserted into From by an |
| 3815 | // insertvalue instruction somewhere). |
| 3816 | // |
| 3817 | // All inserted insertvalue instructions are inserted before InsertBefore |
| 3818 | static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range, |
| 3819 | Instruction *InsertBefore) { |
| 3820 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3820, __PRETTY_FUNCTION__)); |
| 3821 | Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), |
| 3822 | idx_range); |
| 3823 | Value *To = UndefValue::get(IndexedType); |
| 3824 | SmallVector<unsigned, 10> Idxs(idx_range.begin(), idx_range.end()); |
| 3825 | unsigned IdxSkip = Idxs.size(); |
| 3826 | |
| 3827 | return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore); |
| 3828 | } |
| 3829 | |
| 3830 | /// Given an aggregate and a sequence of indices, see if the scalar value |
| 3831 | /// indexed is already around as a register, for example if it was inserted |
| 3832 | /// directly into the aggregate. |
| 3833 | /// |
| 3834 | /// If InsertBefore is not null, this function will duplicate (modified) |
| 3835 | /// insertvalues when a part of a nested struct is extracted. |
| 3836 | Value *llvm::FindInsertedValue(Value *V, ArrayRef<unsigned> idx_range, |
| 3837 | Instruction *InsertBefore) { |
| 3838 | // Nothing to index? Just return V then (this is useful at the end of our |
| 3839 | // recursion). |
| 3840 | if (idx_range.empty()) |
| 3841 | return V; |
| 3842 | // We have indices, so V should have an indexable type. |
| 3843 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3844, __PRETTY_FUNCTION__)) |
| 3844 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3844, __PRETTY_FUNCTION__)); |
| 3845 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3846, __PRETTY_FUNCTION__)) |
| 3846 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3846, __PRETTY_FUNCTION__)); |
| 3847 | |
| 3848 | if (Constant *C = dyn_cast<Constant>(V)) { |
| 3849 | C = C->getAggregateElement(idx_range[0]); |
| 3850 | if (!C) return nullptr; |
| 3851 | return FindInsertedValue(C, idx_range.slice(1), InsertBefore); |
| 3852 | } |
| 3853 | |
| 3854 | if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) { |
| 3855 | // Loop the indices for the insertvalue instruction in parallel with the |
| 3856 | // requested indices |
| 3857 | const unsigned *req_idx = idx_range.begin(); |
| 3858 | for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); |
| 3859 | i != e; ++i, ++req_idx) { |
| 3860 | if (req_idx == idx_range.end()) { |
| 3861 | // We can't handle this without inserting insertvalues |
| 3862 | if (!InsertBefore) |
| 3863 | return nullptr; |
| 3864 | |
| 3865 | // The requested index identifies a part of a nested aggregate. Handle |
| 3866 | // this specially. For example, |
| 3867 | // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0 |
| 3868 | // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1 |
| 3869 | // %C = extractvalue {i32, { i32, i32 } } %B, 1 |
| 3870 | // This can be changed into |
| 3871 | // %A = insertvalue {i32, i32 } undef, i32 10, 0 |
| 3872 | // %C = insertvalue {i32, i32 } %A, i32 11, 1 |
| 3873 | // which allows the unused 0,0 element from the nested struct to be |
| 3874 | // removed. |
| 3875 | return BuildSubAggregate(V, makeArrayRef(idx_range.begin(), req_idx), |
| 3876 | InsertBefore); |
| 3877 | } |
| 3878 | |
| 3879 | // This insert value inserts something else than what we are looking for. |
| 3880 | // See if the (aggregate) value inserted into has the value we are |
| 3881 | // looking for, then. |
| 3882 | if (*req_idx != *i) |
| 3883 | return FindInsertedValue(I->getAggregateOperand(), idx_range, |
| 3884 | InsertBefore); |
| 3885 | } |
| 3886 | // If we end up here, the indices of the insertvalue match with those |
| 3887 | // requested (though possibly only partially). Now we recursively look at |
| 3888 | // the inserted value, passing any remaining indices. |
| 3889 | return FindInsertedValue(I->getInsertedValueOperand(), |
| 3890 | makeArrayRef(req_idx, idx_range.end()), |
| 3891 | InsertBefore); |
| 3892 | } |
| 3893 | |
| 3894 | if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) { |
| 3895 | // If we're extracting a value from an aggregate that was extracted from |
| 3896 | // something else, we can extract from that something else directly instead. |
| 3897 | // However, we will need to chain I's indices with the requested indices. |
| 3898 | |
| 3899 | // Calculate the number of indices required |
| 3900 | unsigned size = I->getNumIndices() + idx_range.size(); |
| 3901 | // Allocate some space to put the new indices in |
| 3902 | SmallVector<unsigned, 5> Idxs; |
| 3903 | Idxs.reserve(size); |
| 3904 | // Add indices from the extract value instruction |
| 3905 | Idxs.append(I->idx_begin(), I->idx_end()); |
| 3906 | |
| 3907 | // Add requested indices |
| 3908 | Idxs.append(idx_range.begin(), idx_range.end()); |
| 3909 | |
| 3910 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3911, __PRETTY_FUNCTION__)) |
| 3911 | && "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3911, __PRETTY_FUNCTION__)); |
| 3912 | |
| 3913 | return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore); |
| 3914 | } |
| 3915 | // Otherwise, we don't know (such as, extracting from a function return value |
| 3916 | // or load instruction) |
| 3917 | return nullptr; |
| 3918 | } |
| 3919 | |
| 3920 | bool llvm::isGEPBasedOnPointerToString(const GEPOperator *GEP, |
| 3921 | unsigned CharSize) { |
| 3922 | // Make sure the GEP has exactly three arguments. |
| 3923 | if (GEP->getNumOperands() != 3) |
| 3924 | return false; |
| 3925 | |
| 3926 | // Make sure the index-ee is a pointer to array of \p CharSize integers. |
| 3927 | // CharSize. |
| 3928 | ArrayType *AT = dyn_cast<ArrayType>(GEP->getSourceElementType()); |
| 3929 | if (!AT || !AT->getElementType()->isIntegerTy(CharSize)) |
| 3930 | return false; |
| 3931 | |
| 3932 | // Check to make sure that the first operand of the GEP is an integer and |
| 3933 | // has value 0 so that we are sure we're indexing into the initializer. |
| 3934 | const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1)); |
| 3935 | if (!FirstIdx || !FirstIdx->isZero()) |
| 3936 | return false; |
| 3937 | |
| 3938 | return true; |
| 3939 | } |
| 3940 | |
| 3941 | bool llvm::getConstantDataArrayInfo(const Value *V, |
| 3942 | ConstantDataArraySlice &Slice, |
| 3943 | unsigned ElementSize, uint64_t Offset) { |
| 3944 | assert(V)((V) ? static_cast<void> (0) : __assert_fail ("V", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 3944, __PRETTY_FUNCTION__)); |
| 3945 | |
| 3946 | // Look through bitcast instructions and geps. |
| 3947 | V = V->stripPointerCasts(); |
| 3948 | |
| 3949 | // If the value is a GEP instruction or constant expression, treat it as an |
| 3950 | // offset. |
| 3951 | if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { |
| 3952 | // The GEP operator should be based on a pointer to string constant, and is |
| 3953 | // indexing into the string constant. |
| 3954 | if (!isGEPBasedOnPointerToString(GEP, ElementSize)) |
| 3955 | return false; |
| 3956 | |
| 3957 | // If the second index isn't a ConstantInt, then this is a variable index |
| 3958 | // into the array. If this occurs, we can't say anything meaningful about |
| 3959 | // the string. |
| 3960 | uint64_t StartIdx = 0; |
| 3961 | if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2))) |
| 3962 | StartIdx = CI->getZExtValue(); |
| 3963 | else |
| 3964 | return false; |
| 3965 | return getConstantDataArrayInfo(GEP->getOperand(0), Slice, ElementSize, |
| 3966 | StartIdx + Offset); |
| 3967 | } |
| 3968 | |
| 3969 | // The GEP instruction, constant or instruction, must reference a global |
| 3970 | // variable that is a constant and is initialized. The referenced constant |
| 3971 | // initializer is the array that we'll use for optimization. |
| 3972 | const GlobalVariable *GV = dyn_cast<GlobalVariable>(V); |
| 3973 | if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer()) |
| 3974 | return false; |
| 3975 | |
| 3976 | const ConstantDataArray *Array; |
| 3977 | ArrayType *ArrayTy; |
| 3978 | if (GV->getInitializer()->isNullValue()) { |
| 3979 | Type *GVTy = GV->getValueType(); |
| 3980 | if ( (ArrayTy = dyn_cast<ArrayType>(GVTy)) ) { |
| 3981 | // A zeroinitializer for the array; there is no ConstantDataArray. |
| 3982 | Array = nullptr; |
| 3983 | } else { |
| 3984 | const DataLayout &DL = GV->getParent()->getDataLayout(); |
| 3985 | uint64_t SizeInBytes = DL.getTypeStoreSize(GVTy).getFixedSize(); |
| 3986 | uint64_t Length = SizeInBytes / (ElementSize / 8); |
| 3987 | if (Length <= Offset) |
| 3988 | return false; |
| 3989 | |
| 3990 | Slice.Array = nullptr; |
| 3991 | Slice.Offset = 0; |
| 3992 | Slice.Length = Length - Offset; |
| 3993 | return true; |
| 3994 | } |
| 3995 | } else { |
| 3996 | // This must be a ConstantDataArray. |
| 3997 | Array = dyn_cast<ConstantDataArray>(GV->getInitializer()); |
| 3998 | if (!Array) |
| 3999 | return false; |
| 4000 | ArrayTy = Array->getType(); |
| 4001 | } |
| 4002 | if (!ArrayTy->getElementType()->isIntegerTy(ElementSize)) |
| 4003 | return false; |
| 4004 | |
| 4005 | uint64_t NumElts = ArrayTy->getArrayNumElements(); |
| 4006 | if (Offset > NumElts) |
| 4007 | return false; |
| 4008 | |
| 4009 | Slice.Array = Array; |
| 4010 | Slice.Offset = Offset; |
| 4011 | Slice.Length = NumElts - Offset; |
| 4012 | return true; |
| 4013 | } |
| 4014 | |
| 4015 | /// This function computes the length of a null-terminated C string pointed to |
| 4016 | /// by V. If successful, it returns true and returns the string in Str. |
| 4017 | /// If unsuccessful, it returns false. |
| 4018 | bool llvm::getConstantStringInfo(const Value *V, StringRef &Str, |
| 4019 | uint64_t Offset, bool TrimAtNul) { |
| 4020 | ConstantDataArraySlice Slice; |
| 4021 | if (!getConstantDataArrayInfo(V, Slice, 8, Offset)) |
| 4022 | return false; |
| 4023 | |
| 4024 | if (Slice.Array == nullptr) { |
| 4025 | if (TrimAtNul) { |
| 4026 | Str = StringRef(); |
| 4027 | return true; |
| 4028 | } |
| 4029 | if (Slice.Length == 1) { |
| 4030 | Str = StringRef("", 1); |
| 4031 | return true; |
| 4032 | } |
| 4033 | // We cannot instantiate a StringRef as we do not have an appropriate string |
| 4034 | // of 0s at hand. |
| 4035 | return false; |
| 4036 | } |
| 4037 | |
| 4038 | // Start out with the entire array in the StringRef. |
| 4039 | Str = Slice.Array->getAsString(); |
| 4040 | // Skip over 'offset' bytes. |
| 4041 | Str = Str.substr(Slice.Offset); |
| 4042 | |
| 4043 | if (TrimAtNul) { |
| 4044 | // Trim off the \0 and anything after it. If the array is not nul |
| 4045 | // terminated, we just return the whole end of string. The client may know |
| 4046 | // some other way that the string is length-bound. |
| 4047 | Str = Str.substr(0, Str.find('\0')); |
| 4048 | } |
| 4049 | return true; |
| 4050 | } |
| 4051 | |
| 4052 | // These next two are very similar to the above, but also look through PHI |
| 4053 | // nodes. |
| 4054 | // TODO: See if we can integrate these two together. |
| 4055 | |
| 4056 | /// If we can compute the length of the string pointed to by |
| 4057 | /// the specified pointer, return 'len+1'. If we can't, return 0. |
| 4058 | static uint64_t GetStringLengthH(const Value *V, |
| 4059 | SmallPtrSetImpl<const PHINode*> &PHIs, |
| 4060 | unsigned CharSize) { |
| 4061 | // Look through noop bitcast instructions. |
| 4062 | V = V->stripPointerCasts(); |
| 4063 | |
| 4064 | // If this is a PHI node, there are two cases: either we have already seen it |
| 4065 | // or we haven't. |
| 4066 | if (const PHINode *PN = dyn_cast<PHINode>(V)) { |
| 4067 | if (!PHIs.insert(PN).second) |
| 4068 | return ~0ULL; // already in the set. |
| 4069 | |
| 4070 | // If it was new, see if all the input strings are the same length. |
| 4071 | uint64_t LenSoFar = ~0ULL; |
| 4072 | for (Value *IncValue : PN->incoming_values()) { |
| 4073 | uint64_t Len = GetStringLengthH(IncValue, PHIs, CharSize); |
| 4074 | if (Len == 0) return 0; // Unknown length -> unknown. |
| 4075 | |
| 4076 | if (Len == ~0ULL) continue; |
| 4077 | |
| 4078 | if (Len != LenSoFar && LenSoFar != ~0ULL) |
| 4079 | return 0; // Disagree -> unknown. |
| 4080 | LenSoFar = Len; |
| 4081 | } |
| 4082 | |
| 4083 | // Success, all agree. |
| 4084 | return LenSoFar; |
| 4085 | } |
| 4086 | |
| 4087 | // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y) |
| 4088 | if (const SelectInst *SI = dyn_cast<SelectInst>(V)) { |
| 4089 | uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs, CharSize); |
| 4090 | if (Len1 == 0) return 0; |
| 4091 | uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs, CharSize); |
| 4092 | if (Len2 == 0) return 0; |
| 4093 | if (Len1 == ~0ULL) return Len2; |
| 4094 | if (Len2 == ~0ULL) return Len1; |
| 4095 | if (Len1 != Len2) return 0; |
| 4096 | return Len1; |
| 4097 | } |
| 4098 | |
| 4099 | // Otherwise, see if we can read the string. |
| 4100 | ConstantDataArraySlice Slice; |
| 4101 | if (!getConstantDataArrayInfo(V, Slice, CharSize)) |
| 4102 | return 0; |
| 4103 | |
| 4104 | if (Slice.Array == nullptr) |
| 4105 | return 1; |
| 4106 | |
| 4107 | // Search for nul characters |
| 4108 | unsigned NullIndex = 0; |
| 4109 | for (unsigned E = Slice.Length; NullIndex < E; ++NullIndex) { |
| 4110 | if (Slice.Array->getElementAsInteger(Slice.Offset + NullIndex) == 0) |
| 4111 | break; |
| 4112 | } |
| 4113 | |
| 4114 | return NullIndex + 1; |
| 4115 | } |
| 4116 | |
| 4117 | /// If we can compute the length of the string pointed to by |
| 4118 | /// the specified pointer, return 'len+1'. If we can't, return 0. |
| 4119 | uint64_t llvm::GetStringLength(const Value *V, unsigned CharSize) { |
| 4120 | if (!V->getType()->isPointerTy()) |
| 4121 | return 0; |
| 4122 | |
| 4123 | SmallPtrSet<const PHINode*, 32> PHIs; |
| 4124 | uint64_t Len = GetStringLengthH(V, PHIs, CharSize); |
| 4125 | // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return |
| 4126 | // an empty string as a length. |
| 4127 | return Len == ~0ULL ? 1 : Len; |
| 4128 | } |
| 4129 | |
| 4130 | const Value * |
| 4131 | llvm::getArgumentAliasingToReturnedPointer(const CallBase *Call, |
| 4132 | bool MustPreserveNullness) { |
| 4133 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4134, __PRETTY_FUNCTION__)) |
| 4134 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4134, __PRETTY_FUNCTION__)); |
| 4135 | if (const Value *RV = Call->getReturnedArgOperand()) |
| 4136 | return RV; |
| 4137 | // This can be used only as a aliasing property. |
| 4138 | if (isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( |
| 4139 | Call, MustPreserveNullness)) |
| 4140 | return Call->getArgOperand(0); |
| 4141 | return nullptr; |
| 4142 | } |
| 4143 | |
| 4144 | bool llvm::isIntrinsicReturningPointerAliasingArgumentWithoutCapturing( |
| 4145 | const CallBase *Call, bool MustPreserveNullness) { |
| 4146 | switch (Call->getIntrinsicID()) { |
| 4147 | case Intrinsic::launder_invariant_group: |
| 4148 | case Intrinsic::strip_invariant_group: |
| 4149 | case Intrinsic::aarch64_irg: |
| 4150 | case Intrinsic::aarch64_tagp: |
| 4151 | return true; |
| 4152 | case Intrinsic::ptrmask: |
| 4153 | return !MustPreserveNullness; |
| 4154 | default: |
| 4155 | return false; |
| 4156 | } |
| 4157 | } |
| 4158 | |
| 4159 | /// \p PN defines a loop-variant pointer to an object. Check if the |
| 4160 | /// previous iteration of the loop was referring to the same object as \p PN. |
| 4161 | static bool isSameUnderlyingObjectInLoop(const PHINode *PN, |
| 4162 | const LoopInfo *LI) { |
| 4163 | // Find the loop-defined value. |
| 4164 | Loop *L = LI->getLoopFor(PN->getParent()); |
| 4165 | if (PN->getNumIncomingValues() != 2) |
| 4166 | return true; |
| 4167 | |
| 4168 | // Find the value from previous iteration. |
| 4169 | auto *PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(0)); |
| 4170 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) |
| 4171 | PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(1)); |
| 4172 | if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L) |
| 4173 | return true; |
| 4174 | |
| 4175 | // If a new pointer is loaded in the loop, the pointer references a different |
| 4176 | // object in every iteration. E.g.: |
| 4177 | // for (i) |
| 4178 | // int *p = a[i]; |
| 4179 | // ... |
| 4180 | if (auto *Load = dyn_cast<LoadInst>(PrevValue)) |
| 4181 | if (!L->isLoopInvariant(Load->getPointerOperand())) |
| 4182 | return false; |
| 4183 | return true; |
| 4184 | } |
| 4185 | |
| 4186 | Value *llvm::getUnderlyingObject(Value *V, unsigned MaxLookup) { |
| 4187 | if (!V->getType()->isPointerTy()) |
| 4188 | return V; |
| 4189 | for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) { |
| 4190 | if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { |
| 4191 | V = GEP->getPointerOperand(); |
| 4192 | } else if (Operator::getOpcode(V) == Instruction::BitCast || |
| 4193 | Operator::getOpcode(V) == Instruction::AddrSpaceCast) { |
| 4194 | V = cast<Operator>(V)->getOperand(0); |
| 4195 | if (!V->getType()->isPointerTy()) |
| 4196 | return V; |
| 4197 | } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { |
| 4198 | if (GA->isInterposable()) |
| 4199 | return V; |
| 4200 | V = GA->getAliasee(); |
| 4201 | } else { |
| 4202 | if (auto *PHI = dyn_cast<PHINode>(V)) { |
| 4203 | // Look through single-arg phi nodes created by LCSSA. |
| 4204 | if (PHI->getNumIncomingValues() == 1) { |
| 4205 | V = PHI->getIncomingValue(0); |
| 4206 | continue; |
| 4207 | } |
| 4208 | } else if (auto *Call = dyn_cast<CallBase>(V)) { |
| 4209 | // CaptureTracking can know about special capturing properties of some |
| 4210 | // intrinsics like launder.invariant.group, that can't be expressed with |
| 4211 | // the attributes, but have properties like returning aliasing pointer. |
| 4212 | // Because some analysis may assume that nocaptured pointer is not |
| 4213 | // returned from some special intrinsic (because function would have to |
| 4214 | // be marked with returns attribute), it is crucial to use this function |
| 4215 | // because it should be in sync with CaptureTracking. Not using it may |
| 4216 | // cause weird miscompilations where 2 aliasing pointers are assumed to |
| 4217 | // noalias. |
| 4218 | if (auto *RP = getArgumentAliasingToReturnedPointer(Call, false)) { |
| 4219 | V = RP; |
| 4220 | continue; |
| 4221 | } |
| 4222 | } |
| 4223 | |
| 4224 | return V; |
| 4225 | } |
| 4226 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4226, __PRETTY_FUNCTION__)); |
| 4227 | } |
| 4228 | return V; |
| 4229 | } |
| 4230 | |
| 4231 | void llvm::getUnderlyingObjects(const Value *V, |
| 4232 | SmallVectorImpl<const Value *> &Objects, |
| 4233 | LoopInfo *LI, unsigned MaxLookup) { |
| 4234 | SmallPtrSet<const Value *, 4> Visited; |
| 4235 | SmallVector<const Value *, 4> Worklist; |
| 4236 | Worklist.push_back(V); |
| 4237 | do { |
| 4238 | const Value *P = Worklist.pop_back_val(); |
| 4239 | P = getUnderlyingObject(P, MaxLookup); |
| 4240 | |
| 4241 | if (!Visited.insert(P).second) |
| 4242 | continue; |
| 4243 | |
| 4244 | if (auto *SI = dyn_cast<SelectInst>(P)) { |
| 4245 | Worklist.push_back(SI->getTrueValue()); |
| 4246 | Worklist.push_back(SI->getFalseValue()); |
| 4247 | continue; |
| 4248 | } |
| 4249 | |
| 4250 | if (auto *PN = dyn_cast<PHINode>(P)) { |
| 4251 | // If this PHI changes the underlying object in every iteration of the |
| 4252 | // loop, don't look through it. Consider: |
| 4253 | // int **A; |
| 4254 | // for (i) { |
| 4255 | // Prev = Curr; // Prev = PHI (Prev_0, Curr) |
| 4256 | // Curr = A[i]; |
| 4257 | // *Prev, *Curr; |
| 4258 | // |
| 4259 | // Prev is tracking Curr one iteration behind so they refer to different |
| 4260 | // underlying objects. |
| 4261 | if (!LI || !LI->isLoopHeader(PN->getParent()) || |
| 4262 | isSameUnderlyingObjectInLoop(PN, LI)) |
| 4263 | append_range(Worklist, PN->incoming_values()); |
| 4264 | continue; |
| 4265 | } |
| 4266 | |
| 4267 | Objects.push_back(P); |
| 4268 | } while (!Worklist.empty()); |
| 4269 | } |
| 4270 | |
| 4271 | /// This is the function that does the work of looking through basic |
| 4272 | /// ptrtoint+arithmetic+inttoptr sequences. |
| 4273 | static const Value *getUnderlyingObjectFromInt(const Value *V) { |
| 4274 | do { |
| 4275 | if (const Operator *U = dyn_cast<Operator>(V)) { |
| 4276 | // If we find a ptrtoint, we can transfer control back to the |
| 4277 | // regular getUnderlyingObjectFromInt. |
| 4278 | if (U->getOpcode() == Instruction::PtrToInt) |
| 4279 | return U->getOperand(0); |
| 4280 | // If we find an add of a constant, a multiplied value, or a phi, it's |
| 4281 | // likely that the other operand will lead us to the base |
| 4282 | // object. We don't have to worry about the case where the |
| 4283 | // object address is somehow being computed by the multiply, |
| 4284 | // because our callers only care when the result is an |
| 4285 | // identifiable object. |
| 4286 | if (U->getOpcode() != Instruction::Add || |
| 4287 | (!isa<ConstantInt>(U->getOperand(1)) && |
| 4288 | Operator::getOpcode(U->getOperand(1)) != Instruction::Mul && |
| 4289 | !isa<PHINode>(U->getOperand(1)))) |
| 4290 | return V; |
| 4291 | V = U->getOperand(0); |
| 4292 | } else { |
| 4293 | return V; |
| 4294 | } |
| 4295 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4295, __PRETTY_FUNCTION__)); |
| 4296 | } while (true); |
| 4297 | } |
| 4298 | |
| 4299 | /// This is a wrapper around getUnderlyingObjects and adds support for basic |
| 4300 | /// ptrtoint+arithmetic+inttoptr sequences. |
| 4301 | /// It returns false if unidentified object is found in getUnderlyingObjects. |
| 4302 | bool llvm::getUnderlyingObjectsForCodeGen(const Value *V, |
| 4303 | SmallVectorImpl<Value *> &Objects) { |
| 4304 | SmallPtrSet<const Value *, 16> Visited; |
| 4305 | SmallVector<const Value *, 4> Working(1, V); |
| 4306 | do { |
| 4307 | V = Working.pop_back_val(); |
| 4308 | |
| 4309 | SmallVector<const Value *, 4> Objs; |
| 4310 | getUnderlyingObjects(V, Objs); |
| 4311 | |
| 4312 | for (const Value *V : Objs) { |
| 4313 | if (!Visited.insert(V).second) |
| 4314 | continue; |
| 4315 | if (Operator::getOpcode(V) == Instruction::IntToPtr) { |
| 4316 | const Value *O = |
| 4317 | getUnderlyingObjectFromInt(cast<User>(V)->getOperand(0)); |
| 4318 | if (O->getType()->isPointerTy()) { |
| 4319 | Working.push_back(O); |
| 4320 | continue; |
| 4321 | } |
| 4322 | } |
| 4323 | // If getUnderlyingObjects fails to find an identifiable object, |
| 4324 | // getUnderlyingObjectsForCodeGen also fails for safety. |
| 4325 | if (!isIdentifiedObject(V)) { |
| 4326 | Objects.clear(); |
| 4327 | return false; |
| 4328 | } |
| 4329 | Objects.push_back(const_cast<Value *>(V)); |
| 4330 | } |
| 4331 | } while (!Working.empty()); |
| 4332 | return true; |
| 4333 | } |
| 4334 | |
| 4335 | AllocaInst *llvm::findAllocaForValue(Value *V, bool OffsetZero) { |
| 4336 | AllocaInst *Result = nullptr; |
| 4337 | SmallPtrSet<Value *, 4> Visited; |
| 4338 | SmallVector<Value *, 4> Worklist; |
| 4339 | |
| 4340 | auto AddWork = [&](Value *V) { |
| 4341 | if (Visited.insert(V).second) |
| 4342 | Worklist.push_back(V); |
| 4343 | }; |
| 4344 | |
| 4345 | AddWork(V); |
| 4346 | do { |
| 4347 | V = Worklist.pop_back_val(); |
| 4348 | assert(Visited.count(V))((Visited.count(V)) ? static_cast<void> (0) : __assert_fail ("Visited.count(V)", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4348, __PRETTY_FUNCTION__)); |
| 4349 | |
| 4350 | if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) { |
| 4351 | if (Result && Result != AI) |
| 4352 | return nullptr; |
| 4353 | Result = AI; |
| 4354 | } else if (CastInst *CI = dyn_cast<CastInst>(V)) { |
| 4355 | AddWork(CI->getOperand(0)); |
| 4356 | } else if (PHINode *PN = dyn_cast<PHINode>(V)) { |
| 4357 | for (Value *IncValue : PN->incoming_values()) |
| 4358 | AddWork(IncValue); |
| 4359 | } else if (auto *SI = dyn_cast<SelectInst>(V)) { |
| 4360 | AddWork(SI->getTrueValue()); |
| 4361 | AddWork(SI->getFalseValue()); |
| 4362 | } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) { |
| 4363 | if (OffsetZero && !GEP->hasAllZeroIndices()) |
| 4364 | return nullptr; |
| 4365 | AddWork(GEP->getPointerOperand()); |
| 4366 | } else { |
| 4367 | return nullptr; |
| 4368 | } |
| 4369 | } while (!Worklist.empty()); |
| 4370 | |
| 4371 | return Result; |
| 4372 | } |
| 4373 | |
| 4374 | static bool onlyUsedByLifetimeMarkersOrDroppableInstsHelper( |
| 4375 | const Value *V, bool AllowLifetime, bool AllowDroppable) { |
| 4376 | for (const User *U : V->users()) { |
| 4377 | const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U); |
| 4378 | if (!II) |
| 4379 | return false; |
| 4380 | |
| 4381 | if (AllowLifetime && II->isLifetimeStartOrEnd()) |
| 4382 | continue; |
| 4383 | |
| 4384 | if (AllowDroppable && II->isDroppable()) |
| 4385 | continue; |
| 4386 | |
| 4387 | return false; |
| 4388 | } |
| 4389 | return true; |
| 4390 | } |
| 4391 | |
| 4392 | bool llvm::onlyUsedByLifetimeMarkers(const Value *V) { |
| 4393 | return onlyUsedByLifetimeMarkersOrDroppableInstsHelper( |
| 4394 | V, /* AllowLifetime */ true, /* AllowDroppable */ false); |
| 4395 | } |
| 4396 | bool llvm::onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V) { |
| 4397 | return onlyUsedByLifetimeMarkersOrDroppableInstsHelper( |
| 4398 | V, /* AllowLifetime */ true, /* AllowDroppable */ true); |
| 4399 | } |
| 4400 | |
| 4401 | bool llvm::mustSuppressSpeculation(const LoadInst &LI) { |
| 4402 | if (!LI.isUnordered()) |
| 4403 | return true; |
| 4404 | const Function &F = *LI.getFunction(); |
| 4405 | // Speculative load may create a race that did not exist in the source. |
| 4406 | return F.hasFnAttribute(Attribute::SanitizeThread) || |
| 4407 | // Speculative load may load data from dirty regions. |
| 4408 | F.hasFnAttribute(Attribute::SanitizeAddress) || |
| 4409 | F.hasFnAttribute(Attribute::SanitizeHWAddress); |
| 4410 | } |
| 4411 | |
| 4412 | |
| 4413 | bool llvm::isSafeToSpeculativelyExecute(const Value *V, |
| 4414 | const Instruction *CtxI, |
| 4415 | const DominatorTree *DT) { |
| 4416 | const Operator *Inst = dyn_cast<Operator>(V); |
| 4417 | if (!Inst) |
| 4418 | return false; |
| 4419 | |
| 4420 | for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i) |
| 4421 | if (Constant *C = dyn_cast<Constant>(Inst->getOperand(i))) |
| 4422 | if (C->canTrap()) |
| 4423 | return false; |
| 4424 | |
| 4425 | switch (Inst->getOpcode()) { |
| 4426 | default: |
| 4427 | return true; |
| 4428 | case Instruction::UDiv: |
| 4429 | case Instruction::URem: { |
| 4430 | // x / y is undefined if y == 0. |
| 4431 | const APInt *V; |
| 4432 | if (match(Inst->getOperand(1), m_APInt(V))) |
| 4433 | return *V != 0; |
| 4434 | return false; |
| 4435 | } |
| 4436 | case Instruction::SDiv: |
| 4437 | case Instruction::SRem: { |
| 4438 | // x / y is undefined if y == 0 or x == INT_MIN and y == -1 |
| 4439 | const APInt *Numerator, *Denominator; |
| 4440 | if (!match(Inst->getOperand(1), m_APInt(Denominator))) |
| 4441 | return false; |
| 4442 | // We cannot hoist this division if the denominator is 0. |
| 4443 | if (*Denominator == 0) |
| 4444 | return false; |
| 4445 | // It's safe to hoist if the denominator is not 0 or -1. |
| 4446 | if (!Denominator->isAllOnesValue()) |
| 4447 | return true; |
| 4448 | // At this point we know that the denominator is -1. It is safe to hoist as |
| 4449 | // long we know that the numerator is not INT_MIN. |
| 4450 | if (match(Inst->getOperand(0), m_APInt(Numerator))) |
| 4451 | return !Numerator->isMinSignedValue(); |
| 4452 | // The numerator *might* be MinSignedValue. |
| 4453 | return false; |
| 4454 | } |
| 4455 | case Instruction::Load: { |
| 4456 | const LoadInst *LI = cast<LoadInst>(Inst); |
| 4457 | if (mustSuppressSpeculation(*LI)) |
| 4458 | return false; |
| 4459 | const DataLayout &DL = LI->getModule()->getDataLayout(); |
| 4460 | return isDereferenceableAndAlignedPointer( |
| 4461 | LI->getPointerOperand(), LI->getType(), MaybeAlign(LI->getAlignment()), |
| 4462 | DL, CtxI, DT); |
| 4463 | } |
| 4464 | case Instruction::Call: { |
| 4465 | auto *CI = cast<const CallInst>(Inst); |
| 4466 | const Function *Callee = CI->getCalledFunction(); |
| 4467 | |
| 4468 | // The called function could have undefined behavior or side-effects, even |
| 4469 | // if marked readnone nounwind. |
| 4470 | return Callee && Callee->isSpeculatable(); |
| 4471 | } |
| 4472 | case Instruction::VAArg: |
| 4473 | case Instruction::Alloca: |
| 4474 | case Instruction::Invoke: |
| 4475 | case Instruction::CallBr: |
| 4476 | case Instruction::PHI: |
| 4477 | case Instruction::Store: |
| 4478 | case Instruction::Ret: |
| 4479 | case Instruction::Br: |
| 4480 | case Instruction::IndirectBr: |
| 4481 | case Instruction::Switch: |
| 4482 | case Instruction::Unreachable: |
| 4483 | case Instruction::Fence: |
| 4484 | case Instruction::AtomicRMW: |
| 4485 | case Instruction::AtomicCmpXchg: |
| 4486 | case Instruction::LandingPad: |
| 4487 | case Instruction::Resume: |
| 4488 | case Instruction::CatchSwitch: |
| 4489 | case Instruction::CatchPad: |
| 4490 | case Instruction::CatchRet: |
| 4491 | case Instruction::CleanupPad: |
| 4492 | case Instruction::CleanupRet: |
| 4493 | return false; // Misc instructions which have effects |
| 4494 | } |
| 4495 | } |
| 4496 | |
| 4497 | bool llvm::mayBeMemoryDependent(const Instruction &I) { |
| 4498 | return I.mayReadOrWriteMemory() || !isSafeToSpeculativelyExecute(&I); |
| 4499 | } |
| 4500 | |
| 4501 | /// Convert ConstantRange OverflowResult into ValueTracking OverflowResult. |
| 4502 | static OverflowResult mapOverflowResult(ConstantRange::OverflowResult OR) { |
| 4503 | switch (OR) { |
| 4504 | case ConstantRange::OverflowResult::MayOverflow: |
| 4505 | return OverflowResult::MayOverflow; |
| 4506 | case ConstantRange::OverflowResult::AlwaysOverflowsLow: |
| 4507 | return OverflowResult::AlwaysOverflowsLow; |
| 4508 | case ConstantRange::OverflowResult::AlwaysOverflowsHigh: |
| 4509 | return OverflowResult::AlwaysOverflowsHigh; |
| 4510 | case ConstantRange::OverflowResult::NeverOverflows: |
| 4511 | return OverflowResult::NeverOverflows; |
| 4512 | } |
| 4513 | llvm_unreachable("Unknown OverflowResult")::llvm::llvm_unreachable_internal("Unknown OverflowResult", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4513); |
| 4514 | } |
| 4515 | |
| 4516 | /// Combine constant ranges from computeConstantRange() and computeKnownBits(). |
| 4517 | static ConstantRange computeConstantRangeIncludingKnownBits( |
| 4518 | const Value *V, bool ForSigned, const DataLayout &DL, unsigned Depth, |
| 4519 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, |
| 4520 | OptimizationRemarkEmitter *ORE = nullptr, bool UseInstrInfo = true) { |
| 4521 | KnownBits Known = computeKnownBits( |
| 4522 | V, DL, Depth, AC, CxtI, DT, ORE, UseInstrInfo); |
| 4523 | ConstantRange CR1 = ConstantRange::fromKnownBits(Known, ForSigned); |
| 4524 | ConstantRange CR2 = computeConstantRange(V, UseInstrInfo); |
| 4525 | ConstantRange::PreferredRangeType RangeType = |
| 4526 | ForSigned ? ConstantRange::Signed : ConstantRange::Unsigned; |
| 4527 | return CR1.intersectWith(CR2, RangeType); |
| 4528 | } |
| 4529 | |
| 4530 | OverflowResult llvm::computeOverflowForUnsignedMul( |
| 4531 | const Value *LHS, const Value *RHS, const DataLayout &DL, |
| 4532 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, |
| 4533 | bool UseInstrInfo) { |
| 4534 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, |
| 4535 | nullptr, UseInstrInfo); |
| 4536 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, |
| 4537 | nullptr, UseInstrInfo); |
| 4538 | ConstantRange LHSRange = ConstantRange::fromKnownBits(LHSKnown, false); |
| 4539 | ConstantRange RHSRange = ConstantRange::fromKnownBits(RHSKnown, false); |
| 4540 | return mapOverflowResult(LHSRange.unsignedMulMayOverflow(RHSRange)); |
| 4541 | } |
| 4542 | |
| 4543 | OverflowResult |
| 4544 | llvm::computeOverflowForSignedMul(const Value *LHS, const Value *RHS, |
| 4545 | const DataLayout &DL, AssumptionCache *AC, |
| 4546 | const Instruction *CxtI, |
| 4547 | const DominatorTree *DT, bool UseInstrInfo) { |
| 4548 | // Multiplying n * m significant bits yields a result of n + m significant |
| 4549 | // bits. If the total number of significant bits does not exceed the |
| 4550 | // result bit width (minus 1), there is no overflow. |
| 4551 | // This means if we have enough leading sign bits in the operands |
| 4552 | // we can guarantee that the result does not overflow. |
| 4553 | // Ref: "Hacker's Delight" by Henry Warren |
| 4554 | unsigned BitWidth = LHS->getType()->getScalarSizeInBits(); |
| 4555 | |
| 4556 | // Note that underestimating the number of sign bits gives a more |
| 4557 | // conservative answer. |
| 4558 | unsigned SignBits = ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) + |
| 4559 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT); |
| 4560 | |
| 4561 | // First handle the easy case: if we have enough sign bits there's |
| 4562 | // definitely no overflow. |
| 4563 | if (SignBits > BitWidth + 1) |
| 4564 | return OverflowResult::NeverOverflows; |
| 4565 | |
| 4566 | // There are two ambiguous cases where there can be no overflow: |
| 4567 | // SignBits == BitWidth + 1 and |
| 4568 | // SignBits == BitWidth |
| 4569 | // The second case is difficult to check, therefore we only handle the |
| 4570 | // first case. |
| 4571 | if (SignBits == BitWidth + 1) { |
| 4572 | // It overflows only when both arguments are negative and the true |
| 4573 | // product is exactly the minimum negative number. |
| 4574 | // E.g. mul i16 with 17 sign bits: 0xff00 * 0xff80 = 0x8000 |
| 4575 | // For simplicity we just check if at least one side is not negative. |
| 4576 | KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT, |
| 4577 | nullptr, UseInstrInfo); |
| 4578 | KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT, |
| 4579 | nullptr, UseInstrInfo); |
| 4580 | if (LHSKnown.isNonNegative() || RHSKnown.isNonNegative()) |
| 4581 | return OverflowResult::NeverOverflows; |
| 4582 | } |
| 4583 | return OverflowResult::MayOverflow; |
| 4584 | } |
| 4585 | |
| 4586 | OverflowResult llvm::computeOverflowForUnsignedAdd( |
| 4587 | const Value *LHS, const Value *RHS, const DataLayout &DL, |
| 4588 | AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, |
| 4589 | bool UseInstrInfo) { |
| 4590 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( |
| 4591 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, |
| 4592 | nullptr, UseInstrInfo); |
| 4593 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( |
| 4594 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT, |
| 4595 | nullptr, UseInstrInfo); |
| 4596 | return mapOverflowResult(LHSRange.unsignedAddMayOverflow(RHSRange)); |
| 4597 | } |
| 4598 | |
| 4599 | static OverflowResult computeOverflowForSignedAdd(const Value *LHS, |
| 4600 | const Value *RHS, |
| 4601 | const AddOperator *Add, |
| 4602 | const DataLayout &DL, |
| 4603 | AssumptionCache *AC, |
| 4604 | const Instruction *CxtI, |
| 4605 | const DominatorTree *DT) { |
| 4606 | if (Add && Add->hasNoSignedWrap()) { |
| 4607 | return OverflowResult::NeverOverflows; |
| 4608 | } |
| 4609 | |
| 4610 | // If LHS and RHS each have at least two sign bits, the addition will look |
| 4611 | // like |
| 4612 | // |
| 4613 | // XX..... + |
| 4614 | // YY..... |
| 4615 | // |
| 4616 | // If the carry into the most significant position is 0, X and Y can't both |
| 4617 | // be 1 and therefore the carry out of the addition is also 0. |
| 4618 | // |
| 4619 | // If the carry into the most significant position is 1, X and Y can't both |
| 4620 | // be 0 and therefore the carry out of the addition is also 1. |
| 4621 | // |
| 4622 | // Since the carry into the most significant position is always equal to |
| 4623 | // the carry out of the addition, there is no signed overflow. |
| 4624 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && |
| 4625 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) |
| 4626 | return OverflowResult::NeverOverflows; |
| 4627 | |
| 4628 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( |
| 4629 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); |
| 4630 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( |
| 4631 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); |
| 4632 | OverflowResult OR = |
| 4633 | mapOverflowResult(LHSRange.signedAddMayOverflow(RHSRange)); |
| 4634 | if (OR != OverflowResult::MayOverflow) |
| 4635 | return OR; |
| 4636 | |
| 4637 | // The remaining code needs Add to be available. Early returns if not so. |
| 4638 | if (!Add) |
| 4639 | return OverflowResult::MayOverflow; |
| 4640 | |
| 4641 | // If the sign of Add is the same as at least one of the operands, this add |
| 4642 | // CANNOT overflow. If this can be determined from the known bits of the |
| 4643 | // operands the above signedAddMayOverflow() check will have already done so. |
| 4644 | // The only other way to improve on the known bits is from an assumption, so |
| 4645 | // call computeKnownBitsFromAssume() directly. |
| 4646 | bool LHSOrRHSKnownNonNegative = |
| 4647 | (LHSRange.isAllNonNegative() || RHSRange.isAllNonNegative()); |
| 4648 | bool LHSOrRHSKnownNegative = |
| 4649 | (LHSRange.isAllNegative() || RHSRange.isAllNegative()); |
| 4650 | if (LHSOrRHSKnownNonNegative || LHSOrRHSKnownNegative) { |
| 4651 | KnownBits AddKnown(LHSRange.getBitWidth()); |
| 4652 | computeKnownBitsFromAssume( |
| 4653 | Add, AddKnown, /*Depth=*/0, Query(DL, AC, CxtI, DT, true)); |
| 4654 | if ((AddKnown.isNonNegative() && LHSOrRHSKnownNonNegative) || |
| 4655 | (AddKnown.isNegative() && LHSOrRHSKnownNegative)) |
| 4656 | return OverflowResult::NeverOverflows; |
| 4657 | } |
| 4658 | |
| 4659 | return OverflowResult::MayOverflow; |
| 4660 | } |
| 4661 | |
| 4662 | OverflowResult llvm::computeOverflowForUnsignedSub(const Value *LHS, |
| 4663 | const Value *RHS, |
| 4664 | const DataLayout &DL, |
| 4665 | AssumptionCache *AC, |
| 4666 | const Instruction *CxtI, |
| 4667 | const DominatorTree *DT) { |
| 4668 | // Checking for conditions implied by dominating conditions may be expensive. |
| 4669 | // Limit it to usub_with_overflow calls for now. |
| 4670 | if (match(CxtI, |
| 4671 | m_Intrinsic<Intrinsic::usub_with_overflow>(m_Value(), m_Value()))) |
| 4672 | if (auto C = |
| 4673 | isImpliedByDomCondition(CmpInst::ICMP_UGE, LHS, RHS, CxtI, DL)) { |
| 4674 | if (*C) |
| 4675 | return OverflowResult::NeverOverflows; |
| 4676 | return OverflowResult::AlwaysOverflowsLow; |
| 4677 | } |
| 4678 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( |
| 4679 | LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); |
| 4680 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( |
| 4681 | RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT); |
| 4682 | return mapOverflowResult(LHSRange.unsignedSubMayOverflow(RHSRange)); |
| 4683 | } |
| 4684 | |
| 4685 | OverflowResult llvm::computeOverflowForSignedSub(const Value *LHS, |
| 4686 | const Value *RHS, |
| 4687 | const DataLayout &DL, |
| 4688 | AssumptionCache *AC, |
| 4689 | const Instruction *CxtI, |
| 4690 | const DominatorTree *DT) { |
| 4691 | // If LHS and RHS each have at least two sign bits, the subtraction |
| 4692 | // cannot overflow. |
| 4693 | if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 && |
| 4694 | ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1) |
| 4695 | return OverflowResult::NeverOverflows; |
| 4696 | |
| 4697 | ConstantRange LHSRange = computeConstantRangeIncludingKnownBits( |
| 4698 | LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); |
| 4699 | ConstantRange RHSRange = computeConstantRangeIncludingKnownBits( |
| 4700 | RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT); |
| 4701 | return mapOverflowResult(LHSRange.signedSubMayOverflow(RHSRange)); |
| 4702 | } |
| 4703 | |
| 4704 | bool llvm::isOverflowIntrinsicNoWrap(const WithOverflowInst *WO, |
| 4705 | const DominatorTree &DT) { |
| 4706 | SmallVector<const BranchInst *, 2> GuardingBranches; |
| 4707 | SmallVector<const ExtractValueInst *, 2> Results; |
| 4708 | |
| 4709 | for (const User *U : WO->users()) { |
| 4710 | if (const auto *EVI = dyn_cast<ExtractValueInst>(U)) { |
| 4711 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4711, __PRETTY_FUNCTION__)); |
| 4712 | |
| 4713 | if (EVI->getIndices()[0] == 0) |
| 4714 | Results.push_back(EVI); |
| 4715 | else { |
| 4716 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4716, __PRETTY_FUNCTION__)); |
| 4717 | |
| 4718 | for (const auto *U : EVI->users()) |
| 4719 | if (const auto *B = dyn_cast<BranchInst>(U)) { |
| 4720 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 4720, __PRETTY_FUNCTION__)); |
| 4721 | GuardingBranches.push_back(B); |
| 4722 | } |
| 4723 | } |
| 4724 | } else { |
| 4725 | // We are using the aggregate directly in a way we don't want to analyze |
| 4726 | // here (storing it to a global, say). |
| 4727 | return false; |
| 4728 | } |
| 4729 | } |
| 4730 | |
| 4731 | auto AllUsesGuardedByBranch = [&](const BranchInst *BI) { |
| 4732 | BasicBlockEdge NoWrapEdge(BI->getParent(), BI->getSuccessor(1)); |
| 4733 | if (!NoWrapEdge.isSingleEdge()) |
| 4734 | return false; |
| 4735 | |
| 4736 | // Check if all users of the add are provably no-wrap. |
| 4737 | for (const auto *Result : Results) { |
| 4738 | // If the extractvalue itself is not executed on overflow, the we don't |
| 4739 | // need to check each use separately, since domination is transitive. |
| 4740 | if (DT.dominates(NoWrapEdge, Result->getParent())) |
| 4741 | continue; |
| 4742 | |
| 4743 | for (auto &RU : Result->uses()) |
| 4744 | if (!DT.dominates(NoWrapEdge, RU)) |
| 4745 | return false; |
| 4746 | } |
| 4747 | |
| 4748 | return true; |
| 4749 | }; |
| 4750 | |
| 4751 | return llvm::any_of(GuardingBranches, AllUsesGuardedByBranch); |
| 4752 | } |
| 4753 | |
| 4754 | static bool canCreateUndefOrPoison(const Operator *Op, bool PoisonOnly) { |
| 4755 | // See whether I has flags that may create poison |
| 4756 | if (const auto *OvOp = dyn_cast<OverflowingBinaryOperator>(Op)) { |
| 4757 | if (OvOp->hasNoSignedWrap() || OvOp->hasNoUnsignedWrap()) |
| 4758 | return true; |
| 4759 | } |
| 4760 | if (const auto *ExactOp = dyn_cast<PossiblyExactOperator>(Op)) |
| 4761 | if (ExactOp->isExact()) |
| 4762 | return true; |
| 4763 | if (const auto *FP = dyn_cast<FPMathOperator>(Op)) { |
| 4764 | auto FMF = FP->getFastMathFlags(); |
| 4765 | if (FMF.noNaNs() || FMF.noInfs()) |
| 4766 | return true; |
| 4767 | } |
| 4768 | |
| 4769 | unsigned Opcode = Op->getOpcode(); |
| 4770 | |
| 4771 | // Check whether opcode is a poison/undef-generating operation |
| 4772 | switch (Opcode) { |
| 4773 | case Instruction::Shl: |
| 4774 | case Instruction::AShr: |
| 4775 | case Instruction::LShr: { |
| 4776 | // Shifts return poison if shiftwidth is larger than the bitwidth. |
| 4777 | if (auto *C = dyn_cast<Constant>(Op->getOperand(1))) { |
| 4778 | SmallVector<Constant *, 4> ShiftAmounts; |
| 4779 | if (auto *FVTy = dyn_cast<FixedVectorType>(C->getType())) { |
| 4780 | unsigned NumElts = FVTy->getNumElements(); |
| 4781 | for (unsigned i = 0; i < NumElts; ++i) |
| 4782 | ShiftAmounts.push_back(C->getAggregateElement(i)); |
| 4783 | } else if (isa<ScalableVectorType>(C->getType())) |
| 4784 | return true; // Can't tell, just return true to be safe |
| 4785 | else |
| 4786 | ShiftAmounts.push_back(C); |
| 4787 | |
| 4788 | bool Safe = llvm::all_of(ShiftAmounts, [](Constant *C) { |
| 4789 | auto *CI = dyn_cast_or_null<ConstantInt>(C); |
| 4790 | return CI && CI->getValue().ult(C->getType()->getIntegerBitWidth()); |
| 4791 | }); |
| 4792 | return !Safe; |
| 4793 | } |
| 4794 | return true; |
| 4795 | } |
| 4796 | case Instruction::FPToSI: |
| 4797 | case Instruction::FPToUI: |
| 4798 | // fptosi/ui yields poison if the resulting value does not fit in the |
| 4799 | // destination type. |
| 4800 | return true; |
| 4801 | case Instruction::Call: |
| 4802 | case Instruction::CallBr: |
| 4803 | case Instruction::Invoke: { |
| 4804 | const auto *CB = cast<CallBase>(Op); |
| 4805 | return !CB->hasRetAttr(Attribute::NoUndef); |
| 4806 | } |
| 4807 | case Instruction::InsertElement: |
| 4808 | case Instruction::ExtractElement: { |
| 4809 | // If index exceeds the length of the vector, it returns poison |
| 4810 | auto *VTy = cast<VectorType>(Op->getOperand(0)->getType()); |
| 4811 | unsigned IdxOp = Op->getOpcode() == Instruction::InsertElement ? 2 : 1; |
| 4812 | auto *Idx = dyn_cast<ConstantInt>(Op->getOperand(IdxOp)); |
| 4813 | if (!Idx || Idx->getValue().uge(VTy->getElementCount().getKnownMinValue())) |
| 4814 | return true; |
| 4815 | return false; |
| 4816 | } |
| 4817 | case Instruction::ShuffleVector: { |
| 4818 | // shufflevector may return undef. |
| 4819 | if (PoisonOnly) |
| 4820 | return false; |
| 4821 | ArrayRef<int> Mask = isa<ConstantExpr>(Op) |
| 4822 | ? cast<ConstantExpr>(Op)->getShuffleMask() |
| 4823 | : cast<ShuffleVectorInst>(Op)->getShuffleMask(); |
| 4824 | return is_contained(Mask, UndefMaskElem); |
| 4825 | } |
| 4826 | case Instruction::FNeg: |
| 4827 | case Instruction::PHI: |
| 4828 | case Instruction::Select: |
| 4829 | case Instruction::URem: |
| 4830 | case Instruction::SRem: |
| 4831 | case Instruction::ExtractValue: |
| 4832 | case Instruction::InsertValue: |
| 4833 | case Instruction::Freeze: |
| 4834 | case Instruction::ICmp: |
| 4835 | case Instruction::FCmp: |
| 4836 | return false; |
| 4837 | case Instruction::GetElementPtr: { |
| 4838 | const auto *GEP = cast<GEPOperator>(Op); |
| 4839 | return GEP->isInBounds(); |
| 4840 | } |
| 4841 | default: { |
| 4842 | const auto *CE = dyn_cast<ConstantExpr>(Op); |
| 4843 | if (isa<CastInst>(Op) || (CE && CE->isCast())) |
| 4844 | return false; |
| 4845 | else if (Instruction::isBinaryOp(Opcode)) |
| 4846 | return false; |
| 4847 | // Be conservative and return true. |
| 4848 | return true; |
| 4849 | } |
| 4850 | } |
| 4851 | } |
| 4852 | |
| 4853 | bool llvm::canCreateUndefOrPoison(const Operator *Op) { |
| 4854 | return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/false); |
| 4855 | } |
| 4856 | |
| 4857 | bool llvm::canCreatePoison(const Operator *Op) { |
| 4858 | return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/true); |
| 4859 | } |
| 4860 | |
| 4861 | static bool directlyImpliesPoison(const Value *ValAssumedPoison, |
| 4862 | const Value *V, unsigned Depth) { |
| 4863 | if (ValAssumedPoison == V) |
| 4864 | return true; |
| 4865 | |
| 4866 | const unsigned MaxDepth = 2; |
| 4867 | if (Depth >= MaxDepth) |
| 4868 | return false; |
| 4869 | |
| 4870 | if (const auto *I = dyn_cast<Instruction>(V)) { |
| 4871 | if (propagatesPoison(cast<Operator>(I))) |
| 4872 | return any_of(I->operands(), [=](const Value *Op) { |
| 4873 | return directlyImpliesPoison(ValAssumedPoison, Op, Depth + 1); |
| 4874 | }); |
| 4875 | |
| 4876 | // V = extractvalue V0, idx |
| 4877 | // V2 = extractvalue V0, idx2 |
| 4878 | // V0's elements are all poison or not. (e.g., add_with_overflow) |
| 4879 | const WithOverflowInst *II; |
| 4880 | if (match(I, m_ExtractValue(m_WithOverflowInst(II))) && |
| 4881 | match(ValAssumedPoison, m_ExtractValue(m_Specific(II)))) |
| 4882 | return true; |
| 4883 | } |
| 4884 | return false; |
| 4885 | } |
| 4886 | |
| 4887 | static bool impliesPoison(const Value *ValAssumedPoison, const Value *V, |
| 4888 | unsigned Depth) { |
| 4889 | if (isGuaranteedNotToBeUndefOrPoison(ValAssumedPoison)) |
| 4890 | return true; |
| 4891 | |
| 4892 | if (directlyImpliesPoison(ValAssumedPoison, V, /* Depth */ 0)) |
| 4893 | return true; |
| 4894 | |
| 4895 | const unsigned MaxDepth = 2; |
| 4896 | if (Depth >= MaxDepth) |
| 4897 | return false; |
| 4898 | |
| 4899 | const auto *I = dyn_cast<Instruction>(ValAssumedPoison); |
| 4900 | if (I && !canCreatePoison(cast<Operator>(I))) { |
| 4901 | return all_of(I->operands(), [=](const Value *Op) { |
| 4902 | return impliesPoison(Op, V, Depth + 1); |
| 4903 | }); |
| 4904 | } |
| 4905 | return false; |
| 4906 | } |
| 4907 | |
| 4908 | bool llvm::impliesPoison(const Value *ValAssumedPoison, const Value *V) { |
| 4909 | return ::impliesPoison(ValAssumedPoison, V, /* Depth */ 0); |
| 4910 | } |
| 4911 | |
| 4912 | static bool programUndefinedIfUndefOrPoison(const Value *V, |
| 4913 | bool PoisonOnly); |
| 4914 | |
| 4915 | static bool isGuaranteedNotToBeUndefOrPoison(const Value *V, |
| 4916 | AssumptionCache *AC, |
| 4917 | const Instruction *CtxI, |
| 4918 | const DominatorTree *DT, |
| 4919 | unsigned Depth, bool PoisonOnly) { |
| 4920 | if (Depth >= MaxAnalysisRecursionDepth) |
| 4921 | return false; |
| 4922 | |
| 4923 | if (isa<MetadataAsValue>(V)) |
| 4924 | return false; |
| 4925 | |
| 4926 | if (const auto *A = dyn_cast<Argument>(V)) { |
| 4927 | if (A->hasAttribute(Attribute::NoUndef)) |
| 4928 | return true; |
| 4929 | } |
| 4930 | |
| 4931 | if (auto *C = dyn_cast<Constant>(V)) { |
| 4932 | if (isa<UndefValue>(C)) |
| 4933 | return PoisonOnly && !isa<PoisonValue>(C); |
| 4934 | |
| 4935 | if (isa<ConstantInt>(C) || isa<GlobalVariable>(C) || isa<ConstantFP>(V) || |
| 4936 | isa<ConstantPointerNull>(C) || isa<Function>(C)) |
| 4937 | return true; |
| 4938 | |
| 4939 | if (C->getType()->isVectorTy() && !isa<ConstantExpr>(C)) |
| 4940 | return (PoisonOnly ? !C->containsPoisonElement() |
| 4941 | : !C->containsUndefOrPoisonElement()) && |
| 4942 | !C->containsConstantExpression(); |
| 4943 | } |
| 4944 | |
| 4945 | // Strip cast operations from a pointer value. |
| 4946 | // Note that stripPointerCastsSameRepresentation can strip off getelementptr |
| 4947 | // inbounds with zero offset. To guarantee that the result isn't poison, the |
| 4948 | // stripped pointer is checked as it has to be pointing into an allocated |
| 4949 | // object or be null `null` to ensure `inbounds` getelement pointers with a |
| 4950 | // zero offset could not produce poison. |
| 4951 | // It can strip off addrspacecast that do not change bit representation as |
| 4952 | // well. We believe that such addrspacecast is equivalent to no-op. |
| 4953 | auto *StrippedV = V->stripPointerCastsSameRepresentation(); |
| 4954 | if (isa<AllocaInst>(StrippedV) || isa<GlobalVariable>(StrippedV) || |
| 4955 | isa<Function>(StrippedV) || isa<ConstantPointerNull>(StrippedV)) |
| 4956 | return true; |
| 4957 | |
| 4958 | auto OpCheck = [&](const Value *V) { |
| 4959 | return isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth + 1, |
| 4960 | PoisonOnly); |
| 4961 | }; |
| 4962 | |
| 4963 | if (auto *Opr = dyn_cast<Operator>(V)) { |
| 4964 | // If the value is a freeze instruction, then it can never |
| 4965 | // be undef or poison. |
| 4966 | if (isa<FreezeInst>(V)) |
| 4967 | return true; |
| 4968 | |
| 4969 | if (const auto *CB = dyn_cast<CallBase>(V)) { |
| 4970 | if (CB->hasRetAttr(Attribute::NoUndef)) |
| 4971 | return true; |
| 4972 | } |
| 4973 | |
| 4974 | if (const auto *PN = dyn_cast<PHINode>(V)) { |
| 4975 | unsigned Num = PN->getNumIncomingValues(); |
| 4976 | bool IsWellDefined = true; |
| 4977 | for (unsigned i = 0; i < Num; ++i) { |
| 4978 | auto *TI = PN->getIncomingBlock(i)->getTerminator(); |
| 4979 | if (!isGuaranteedNotToBeUndefOrPoison(PN->getIncomingValue(i), AC, TI, |
| 4980 | DT, Depth + 1, PoisonOnly)) { |
| 4981 | IsWellDefined = false; |
| 4982 | break; |
| 4983 | } |
| 4984 | } |
| 4985 | if (IsWellDefined) |
| 4986 | return true; |
| 4987 | } else if (!canCreateUndefOrPoison(Opr) && all_of(Opr->operands(), OpCheck)) |
| 4988 | return true; |
| 4989 | } |
| 4990 | |
| 4991 | if (auto *I = dyn_cast<LoadInst>(V)) |
| 4992 | if (I->getMetadata(LLVMContext::MD_noundef)) |
| 4993 | return true; |
| 4994 | |
| 4995 | if (programUndefinedIfUndefOrPoison(V, PoisonOnly)) |
| 4996 | return true; |
| 4997 | |
| 4998 | // CxtI may be null or a cloned instruction. |
| 4999 | if (!CtxI || !CtxI->getParent() || !DT) |
| 5000 | return false; |
| 5001 | |
| 5002 | auto *DNode = DT->getNode(CtxI->getParent()); |
| 5003 | if (!DNode) |
| 5004 | // Unreachable block |
| 5005 | return false; |
| 5006 | |
| 5007 | // If V is used as a branch condition before reaching CtxI, V cannot be |
| 5008 | // undef or poison. |
| 5009 | // br V, BB1, BB2 |
| 5010 | // BB1: |
| 5011 | // CtxI ; V cannot be undef or poison here |
| 5012 | auto *Dominator = DNode->getIDom(); |
| 5013 | while (Dominator) { |
| 5014 | auto *TI = Dominator->getBlock()->getTerminator(); |
| 5015 | |
| 5016 | Value *Cond = nullptr; |
| 5017 | if (auto BI = dyn_cast<BranchInst>(TI)) { |
| 5018 | if (BI->isConditional()) |
| 5019 | Cond = BI->getCondition(); |
| 5020 | } else if (auto SI = dyn_cast<SwitchInst>(TI)) { |
| 5021 | Cond = SI->getCondition(); |
| 5022 | } |
| 5023 | |
| 5024 | if (Cond) { |
| 5025 | if (Cond == V) |
| 5026 | return true; |
| 5027 | else if (PoisonOnly && isa<Operator>(Cond)) { |
| 5028 | // For poison, we can analyze further |
| 5029 | auto *Opr = cast<Operator>(Cond); |
| 5030 | if (propagatesPoison(Opr) && is_contained(Opr->operand_values(), V)) |
| 5031 | return true; |
| 5032 | } |
| 5033 | } |
| 5034 | |
| 5035 | Dominator = Dominator->getIDom(); |
| 5036 | } |
| 5037 | |
| 5038 | SmallVector<Attribute::AttrKind, 2> AttrKinds{Attribute::NoUndef}; |
| 5039 | if (getKnowledgeValidInContext(V, AttrKinds, CtxI, DT, AC)) |
| 5040 | return true; |
| 5041 | |
| 5042 | return false; |
| 5043 | } |
| 5044 | |
| 5045 | bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V, AssumptionCache *AC, |
| 5046 | const Instruction *CtxI, |
| 5047 | const DominatorTree *DT, |
| 5048 | unsigned Depth) { |
| 5049 | return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, false); |
| 5050 | } |
| 5051 | |
| 5052 | bool llvm::isGuaranteedNotToBePoison(const Value *V, AssumptionCache *AC, |
| 5053 | const Instruction *CtxI, |
| 5054 | const DominatorTree *DT, unsigned Depth) { |
| 5055 | return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, true); |
| 5056 | } |
| 5057 | |
| 5058 | OverflowResult llvm::computeOverflowForSignedAdd(const AddOperator *Add, |
| 5059 | const DataLayout &DL, |
| 5060 | AssumptionCache *AC, |
| 5061 | const Instruction *CxtI, |
| 5062 | const DominatorTree *DT) { |
| 5063 | return ::computeOverflowForSignedAdd(Add->getOperand(0), Add->getOperand(1), |
| 5064 | Add, DL, AC, CxtI, DT); |
| 5065 | } |
| 5066 | |
| 5067 | OverflowResult llvm::computeOverflowForSignedAdd(const Value *LHS, |
| 5068 | const Value *RHS, |
| 5069 | const DataLayout &DL, |
| 5070 | AssumptionCache *AC, |
| 5071 | const Instruction *CxtI, |
| 5072 | const DominatorTree *DT) { |
| 5073 | return ::computeOverflowForSignedAdd(LHS, RHS, nullptr, DL, AC, CxtI, DT); |
| 5074 | } |
| 5075 | |
| 5076 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const Instruction *I) { |
| 5077 | // Note: An atomic operation isn't guaranteed to return in a reasonable amount |
| 5078 | // of time because it's possible for another thread to interfere with it for an |
| 5079 | // arbitrary length of time, but programs aren't allowed to rely on that. |
| 5080 | |
| 5081 | // If there is no successor, then execution can't transfer to it. |
| 5082 | if (isa<ReturnInst>(I)) |
| 5083 | return false; |
| 5084 | if (isa<UnreachableInst>(I)) |
| 5085 | return false; |
| 5086 | |
| 5087 | // An instruction that returns without throwing must transfer control flow |
| 5088 | // to a successor. |
| 5089 | return !I->mayThrow() && I->willReturn(); |
| 5090 | } |
| 5091 | |
| 5092 | bool llvm::isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB) { |
| 5093 | // TODO: This is slightly conservative for invoke instruction since exiting |
| 5094 | // via an exception *is* normal control for them. |
| 5095 | for (const Instruction &I : *BB) |
| 5096 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) |
| 5097 | return false; |
| 5098 | return true; |
| 5099 | } |
| 5100 | |
| 5101 | bool llvm::isGuaranteedToExecuteForEveryIteration(const Instruction *I, |
| 5102 | const Loop *L) { |
| 5103 | // The loop header is guaranteed to be executed for every iteration. |
| 5104 | // |
| 5105 | // FIXME: Relax this constraint to cover all basic blocks that are |
| 5106 | // guaranteed to be executed at every iteration. |
| 5107 | if (I->getParent() != L->getHeader()) return false; |
| 5108 | |
| 5109 | for (const Instruction &LI : *L->getHeader()) { |
| 5110 | if (&LI == I) return true; |
| 5111 | if (!isGuaranteedToTransferExecutionToSuccessor(&LI)) return false; |
| 5112 | } |
| 5113 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 5113); |
| 5114 | } |
| 5115 | |
| 5116 | bool llvm::propagatesPoison(const Operator *I) { |
| 5117 | switch (I->getOpcode()) { |
| 5118 | case Instruction::Freeze: |
| 5119 | case Instruction::Select: |
| 5120 | case Instruction::PHI: |
| 5121 | case Instruction::Call: |
| 5122 | case Instruction::Invoke: |
| 5123 | return false; |
| 5124 | case Instruction::ICmp: |
| 5125 | case Instruction::FCmp: |
| 5126 | case Instruction::GetElementPtr: |
| 5127 | return true; |
| 5128 | default: |
| 5129 | if (isa<BinaryOperator>(I) || isa<UnaryOperator>(I) || isa<CastInst>(I)) |
| 5130 | return true; |
| 5131 | |
| 5132 | // Be conservative and return false. |
| 5133 | return false; |
| 5134 | } |
| 5135 | } |
| 5136 | |
| 5137 | void llvm::getGuaranteedWellDefinedOps( |
| 5138 | const Instruction *I, SmallPtrSetImpl<const Value *> &Operands) { |
| 5139 | switch (I->getOpcode()) { |
| 5140 | case Instruction::Store: |
| 5141 | Operands.insert(cast<StoreInst>(I)->getPointerOperand()); |
| 5142 | break; |
| 5143 | |
| 5144 | case Instruction::Load: |
| 5145 | Operands.insert(cast<LoadInst>(I)->getPointerOperand()); |
| 5146 | break; |
| 5147 | |
| 5148 | // Since dereferenceable attribute imply noundef, atomic operations |
| 5149 | // also implicitly have noundef pointers too |
| 5150 | case Instruction::AtomicCmpXchg: |
| 5151 | Operands.insert(cast<AtomicCmpXchgInst>(I)->getPointerOperand()); |
| 5152 | break; |
| 5153 | |
| 5154 | case Instruction::AtomicRMW: |
| 5155 | Operands.insert(cast<AtomicRMWInst>(I)->getPointerOperand()); |
| 5156 | break; |
| 5157 | |
| 5158 | case Instruction::Call: |
| 5159 | case Instruction::Invoke: { |
| 5160 | const CallBase *CB = cast<CallBase>(I); |
| 5161 | if (CB->isIndirectCall()) |
| 5162 | Operands.insert(CB->getCalledOperand()); |
| 5163 | for (unsigned i = 0; i < CB->arg_size(); ++i) { |
| 5164 | if (CB->paramHasAttr(i, Attribute::NoUndef) || |
| 5165 | CB->paramHasAttr(i, Attribute::Dereferenceable)) |
| 5166 | Operands.insert(CB->getArgOperand(i)); |
| 5167 | } |
| 5168 | break; |
| 5169 | } |
| 5170 | |
| 5171 | default: |
| 5172 | break; |
| 5173 | } |
| 5174 | } |
| 5175 | |
| 5176 | void llvm::getGuaranteedNonPoisonOps(const Instruction *I, |
| 5177 | SmallPtrSetImpl<const Value *> &Operands) { |
| 5178 | getGuaranteedWellDefinedOps(I, Operands); |
| 5179 | switch (I->getOpcode()) { |
| 5180 | // Divisors of these operations are allowed to be partially undef. |
| 5181 | case Instruction::UDiv: |
| 5182 | case Instruction::SDiv: |
| 5183 | case Instruction::URem: |
| 5184 | case Instruction::SRem: |
| 5185 | Operands.insert(I->getOperand(1)); |
| 5186 | break; |
| 5187 | |
| 5188 | default: |
| 5189 | break; |
| 5190 | } |
| 5191 | } |
| 5192 | |
| 5193 | bool llvm::mustTriggerUB(const Instruction *I, |
| 5194 | const SmallSet<const Value *, 16>& KnownPoison) { |
| 5195 | SmallPtrSet<const Value *, 4> NonPoisonOps; |
| 5196 | getGuaranteedNonPoisonOps(I, NonPoisonOps); |
| 5197 | |
| 5198 | for (const auto *V : NonPoisonOps) |
| 5199 | if (KnownPoison.count(V)) |
| 5200 | return true; |
| 5201 | |
| 5202 | return false; |
| 5203 | } |
| 5204 | |
| 5205 | static bool programUndefinedIfUndefOrPoison(const Value *V, |
| 5206 | bool PoisonOnly) { |
| 5207 | // We currently only look for uses of values within the same basic |
| 5208 | // block, as that makes it easier to guarantee that the uses will be |
| 5209 | // executed given that Inst is executed. |
| 5210 | // |
| 5211 | // FIXME: Expand this to consider uses beyond the same basic block. To do |
| 5212 | // this, look out for the distinction between post-dominance and strong |
| 5213 | // post-dominance. |
| 5214 | const BasicBlock *BB = nullptr; |
| 5215 | BasicBlock::const_iterator Begin; |
| 5216 | if (const auto *Inst = dyn_cast<Instruction>(V)) { |
| 5217 | BB = Inst->getParent(); |
| 5218 | Begin = Inst->getIterator(); |
| 5219 | Begin++; |
| 5220 | } else if (const auto *Arg = dyn_cast<Argument>(V)) { |
| 5221 | BB = &Arg->getParent()->getEntryBlock(); |
| 5222 | Begin = BB->begin(); |
| 5223 | } else { |
| 5224 | return false; |
| 5225 | } |
| 5226 | |
| 5227 | BasicBlock::const_iterator End = BB->end(); |
| 5228 | |
| 5229 | if (!PoisonOnly) { |
| 5230 | // Since undef does not propagate eagerly, be conservative & just check |
| 5231 | // whether a value is directly passed to an instruction that must take |
| 5232 | // well-defined operands. |
| 5233 | |
| 5234 | for (auto &I : make_range(Begin, End)) { |
| 5235 | SmallPtrSet<const Value *, 4> WellDefinedOps; |
| 5236 | getGuaranteedWellDefinedOps(&I, WellDefinedOps); |
| 5237 | for (auto *Op : WellDefinedOps) { |
| 5238 | if (Op == V) |
| 5239 | return true; |
| 5240 | } |
| 5241 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) |
| 5242 | break; |
| 5243 | } |
| 5244 | return false; |
| 5245 | } |
| 5246 | |
| 5247 | // Set of instructions that we have proved will yield poison if Inst |
| 5248 | // does. |
| 5249 | SmallSet<const Value *, 16> YieldsPoison; |
| 5250 | SmallSet<const BasicBlock *, 4> Visited; |
| 5251 | |
| 5252 | YieldsPoison.insert(V); |
| 5253 | auto Propagate = [&](const User *User) { |
| 5254 | if (propagatesPoison(cast<Operator>(User))) |
| 5255 | YieldsPoison.insert(User); |
| 5256 | }; |
| 5257 | for_each(V->users(), Propagate); |
| 5258 | Visited.insert(BB); |
| 5259 | |
| 5260 | unsigned Iter = 0; |
| 5261 | while (Iter++ < MaxAnalysisRecursionDepth) { |
| 5262 | for (auto &I : make_range(Begin, End)) { |
| 5263 | if (mustTriggerUB(&I, YieldsPoison)) |
| 5264 | return true; |
| 5265 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) |
| 5266 | return false; |
| 5267 | |
| 5268 | // Mark poison that propagates from I through uses of I. |
| 5269 | if (YieldsPoison.count(&I)) |
| 5270 | for_each(I.users(), Propagate); |
| 5271 | } |
| 5272 | |
| 5273 | if (auto *NextBB = BB->getSingleSuccessor()) { |
| 5274 | if (Visited.insert(NextBB).second) { |
| 5275 | BB = NextBB; |
| 5276 | Begin = BB->getFirstNonPHI()->getIterator(); |
| 5277 | End = BB->end(); |
| 5278 | continue; |
| 5279 | } |
| 5280 | } |
| 5281 | |
| 5282 | break; |
| 5283 | } |
| 5284 | return false; |
| 5285 | } |
| 5286 | |
| 5287 | bool llvm::programUndefinedIfUndefOrPoison(const Instruction *Inst) { |
| 5288 | return ::programUndefinedIfUndefOrPoison(Inst, false); |
| 5289 | } |
| 5290 | |
| 5291 | bool llvm::programUndefinedIfPoison(const Instruction *Inst) { |
| 5292 | return ::programUndefinedIfUndefOrPoison(Inst, true); |
| 5293 | } |
| 5294 | |
| 5295 | static bool isKnownNonNaN(const Value *V, FastMathFlags FMF) { |
| 5296 | if (FMF.noNaNs()) |
| 5297 | return true; |
| 5298 | |
| 5299 | if (auto *C = dyn_cast<ConstantFP>(V)) |
| 5300 | return !C->isNaN(); |
| 5301 | |
| 5302 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { |
| 5303 | if (!C->getElementType()->isFloatingPointTy()) |
| 5304 | return false; |
| 5305 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { |
| 5306 | if (C->getElementAsAPFloat(I).isNaN()) |
| 5307 | return false; |
| 5308 | } |
| 5309 | return true; |
| 5310 | } |
| 5311 | |
| 5312 | if (isa<ConstantAggregateZero>(V)) |
| 5313 | return true; |
| 5314 | |
| 5315 | return false; |
| 5316 | } |
| 5317 | |
| 5318 | static bool isKnownNonZero(const Value *V) { |
| 5319 | if (auto *C = dyn_cast<ConstantFP>(V)) |
| 5320 | return !C->isZero(); |
| 5321 | |
| 5322 | if (auto *C = dyn_cast<ConstantDataVector>(V)) { |
| 5323 | if (!C->getElementType()->isFloatingPointTy()) |
| 5324 | return false; |
| 5325 | for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) { |
| 5326 | if (C->getElementAsAPFloat(I).isZero()) |
| 5327 | return false; |
| 5328 | } |
| 5329 | return true; |
| 5330 | } |
| 5331 | |
| 5332 | return false; |
| 5333 | } |
| 5334 | |
| 5335 | /// Match clamp pattern for float types without care about NaNs or signed zeros. |
| 5336 | /// Given non-min/max outer cmp/select from the clamp pattern this |
| 5337 | /// function recognizes if it can be substitued by a "canonical" min/max |
| 5338 | /// pattern. |
| 5339 | static SelectPatternResult matchFastFloatClamp(CmpInst::Predicate Pred, |
| 5340 | Value *CmpLHS, Value *CmpRHS, |
| 5341 | Value *TrueVal, Value *FalseVal, |
| 5342 | Value *&LHS, Value *&RHS) { |
| 5343 | // Try to match |
| 5344 | // X < C1 ? C1 : Min(X, C2) --> Max(C1, Min(X, C2)) |
| 5345 | // X > C1 ? C1 : Max(X, C2) --> Min(C1, Max(X, C2)) |
| 5346 | // and return description of the outer Max/Min. |
| 5347 | |
| 5348 | // First, check if select has inverse order: |
| 5349 | if (CmpRHS == FalseVal) { |
| 5350 | std::swap(TrueVal, FalseVal); |
| 5351 | Pred = CmpInst::getInversePredicate(Pred); |
| 5352 | } |
| 5353 | |
| 5354 | // Assume success now. If there's no match, callers should not use these anyway. |
| 5355 | LHS = TrueVal; |
| 5356 | RHS = FalseVal; |
| 5357 | |
| 5358 | const APFloat *FC1; |
| 5359 | if (CmpRHS != TrueVal || !match(CmpRHS, m_APFloat(FC1)) || !FC1->isFinite()) |
| 5360 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5361 | |
| 5362 | const APFloat *FC2; |
| 5363 | switch (Pred) { |
| 5364 | case CmpInst::FCMP_OLT: |
| 5365 | case CmpInst::FCMP_OLE: |
| 5366 | case CmpInst::FCMP_ULT: |
| 5367 | case CmpInst::FCMP_ULE: |
| 5368 | if (match(FalseVal, |
| 5369 | m_CombineOr(m_OrdFMin(m_Specific(CmpLHS), m_APFloat(FC2)), |
| 5370 | m_UnordFMin(m_Specific(CmpLHS), m_APFloat(FC2)))) && |
| 5371 | *FC1 < *FC2) |
| 5372 | return {SPF_FMAXNUM, SPNB_RETURNS_ANY, false}; |
| 5373 | break; |
| 5374 | case CmpInst::FCMP_OGT: |
| 5375 | case CmpInst::FCMP_OGE: |
| 5376 | case CmpInst::FCMP_UGT: |
| 5377 | case CmpInst::FCMP_UGE: |
| 5378 | if (match(FalseVal, |
| 5379 | m_CombineOr(m_OrdFMax(m_Specific(CmpLHS), m_APFloat(FC2)), |
| 5380 | m_UnordFMax(m_Specific(CmpLHS), m_APFloat(FC2)))) && |
| 5381 | *FC1 > *FC2) |
| 5382 | return {SPF_FMINNUM, SPNB_RETURNS_ANY, false}; |
| 5383 | break; |
| 5384 | default: |
| 5385 | break; |
| 5386 | } |
| 5387 | |
| 5388 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5389 | } |
| 5390 | |
| 5391 | /// Recognize variations of: |
| 5392 | /// CLAMP(v,l,h) ==> ((v) < (l) ? (l) : ((v) > (h) ? (h) : (v))) |
| 5393 | static SelectPatternResult matchClamp(CmpInst::Predicate Pred, |
| 5394 | Value *CmpLHS, Value *CmpRHS, |
| 5395 | Value *TrueVal, Value *FalseVal) { |
| 5396 | // Swap the select operands and predicate to match the patterns below. |
| 5397 | if (CmpRHS != TrueVal) { |
| 5398 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 5399 | std::swap(TrueVal, FalseVal); |
| 5400 | } |
| 5401 | const APInt *C1; |
| 5402 | if (CmpRHS == TrueVal && match(CmpRHS, m_APInt(C1))) { |
| 5403 | const APInt *C2; |
| 5404 | // (X <s C1) ? C1 : SMIN(X, C2) ==> SMAX(SMIN(X, C2), C1) |
| 5405 | if (match(FalseVal, m_SMin(m_Specific(CmpLHS), m_APInt(C2))) && |
| 5406 | C1->slt(*C2) && Pred == CmpInst::ICMP_SLT) |
| 5407 | return {SPF_SMAX, SPNB_NA, false}; |
| 5408 | |
| 5409 | // (X >s C1) ? C1 : SMAX(X, C2) ==> SMIN(SMAX(X, C2), C1) |
| 5410 | if (match(FalseVal, m_SMax(m_Specific(CmpLHS), m_APInt(C2))) && |
| 5411 | C1->sgt(*C2) && Pred == CmpInst::ICMP_SGT) |
| 5412 | return {SPF_SMIN, SPNB_NA, false}; |
| 5413 | |
| 5414 | // (X <u C1) ? C1 : UMIN(X, C2) ==> UMAX(UMIN(X, C2), C1) |
| 5415 | if (match(FalseVal, m_UMin(m_Specific(CmpLHS), m_APInt(C2))) && |
| 5416 | C1->ult(*C2) && Pred == CmpInst::ICMP_ULT) |
| 5417 | return {SPF_UMAX, SPNB_NA, false}; |
| 5418 | |
| 5419 | // (X >u C1) ? C1 : UMAX(X, C2) ==> UMIN(UMAX(X, C2), C1) |
| 5420 | if (match(FalseVal, m_UMax(m_Specific(CmpLHS), m_APInt(C2))) && |
| 5421 | C1->ugt(*C2) && Pred == CmpInst::ICMP_UGT) |
| 5422 | return {SPF_UMIN, SPNB_NA, false}; |
| 5423 | } |
| 5424 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5425 | } |
| 5426 | |
| 5427 | /// Recognize variations of: |
| 5428 | /// a < c ? min(a,b) : min(b,c) ==> min(min(a,b),min(b,c)) |
| 5429 | static SelectPatternResult matchMinMaxOfMinMax(CmpInst::Predicate Pred, |
| 5430 | Value *CmpLHS, Value *CmpRHS, |
| 5431 | Value *TVal, Value *FVal, |
| 5432 | unsigned Depth) { |
| 5433 | // TODO: Allow FP min/max with nnan/nsz. |
| 5434 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 5434, __PRETTY_FUNCTION__)); |
| 5435 | |
| 5436 | Value *A = nullptr, *B = nullptr; |
| 5437 | SelectPatternResult L = matchSelectPattern(TVal, A, B, nullptr, Depth + 1); |
| 5438 | if (!SelectPatternResult::isMinOrMax(L.Flavor)) |
| 5439 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5440 | |
| 5441 | Value *C = nullptr, *D = nullptr; |
| 5442 | SelectPatternResult R = matchSelectPattern(FVal, C, D, nullptr, Depth + 1); |
| 5443 | if (L.Flavor != R.Flavor) |
| 5444 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5445 | |
| 5446 | // We have something like: x Pred y ? min(a, b) : min(c, d). |
| 5447 | // Try to match the compare to the min/max operations of the select operands. |
| 5448 | // First, make sure we have the right compare predicate. |
| 5449 | switch (L.Flavor) { |
| 5450 | case SPF_SMIN: |
| 5451 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) { |
| 5452 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 5453 | std::swap(CmpLHS, CmpRHS); |
| 5454 | } |
| 5455 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) |
| 5456 | break; |
| 5457 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5458 | case SPF_SMAX: |
| 5459 | if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) { |
| 5460 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 5461 | std::swap(CmpLHS, CmpRHS); |
| 5462 | } |
| 5463 | if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) |
| 5464 | break; |
| 5465 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5466 | case SPF_UMIN: |
| 5467 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) { |
| 5468 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 5469 | std::swap(CmpLHS, CmpRHS); |
| 5470 | } |
| 5471 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) |
| 5472 | break; |
| 5473 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5474 | case SPF_UMAX: |
| 5475 | if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { |
| 5476 | Pred = ICmpInst::getSwappedPredicate(Pred); |
| 5477 | std::swap(CmpLHS, CmpRHS); |
| 5478 | } |
| 5479 | if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) |
| 5480 | break; |
| 5481 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5482 | default: |
| 5483 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5484 | } |
| 5485 | |
| 5486 | // If there is a common operand in the already matched min/max and the other |
| 5487 | // min/max operands match the compare operands (either directly or inverted), |
| 5488 | // then this is min/max of the same flavor. |
| 5489 | |
| 5490 | // a pred c ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) |
| 5491 | // ~c pred ~a ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b)) |
| 5492 | if (D == B) { |
| 5493 | if ((CmpLHS == A && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && |
| 5494 | match(A, m_Not(m_Specific(CmpRHS))))) |
| 5495 | return {L.Flavor, SPNB_NA, false}; |
| 5496 | } |
| 5497 | // a pred d ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) |
| 5498 | // ~d pred ~a ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d)) |
| 5499 | if (C == B) { |
| 5500 | if ((CmpLHS == A && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && |
| 5501 | match(A, m_Not(m_Specific(CmpRHS))))) |
| 5502 | return {L.Flavor, SPNB_NA, false}; |
| 5503 | } |
| 5504 | // b pred c ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) |
| 5505 | // ~c pred ~b ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a)) |
| 5506 | if (D == A) { |
| 5507 | if ((CmpLHS == B && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) && |
| 5508 | match(B, m_Not(m_Specific(CmpRHS))))) |
| 5509 | return {L.Flavor, SPNB_NA, false}; |
| 5510 | } |
| 5511 | // b pred d ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) |
| 5512 | // ~d pred ~b ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d)) |
| 5513 | if (C == A) { |
| 5514 | if ((CmpLHS == B && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) && |
| 5515 | match(B, m_Not(m_Specific(CmpRHS))))) |
| 5516 | return {L.Flavor, SPNB_NA, false}; |
| 5517 | } |
| 5518 | |
| 5519 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5520 | } |
| 5521 | |
| 5522 | /// If the input value is the result of a 'not' op, constant integer, or vector |
| 5523 | /// splat of a constant integer, return the bitwise-not source value. |
| 5524 | /// TODO: This could be extended to handle non-splat vector integer constants. |
| 5525 | static Value *getNotValue(Value *V) { |
| 5526 | Value *NotV; |
| 5527 | if (match(V, m_Not(m_Value(NotV)))) |
| 5528 | return NotV; |
| 5529 | |
| 5530 | const APInt *C; |
| 5531 | if (match(V, m_APInt(C))) |
| 5532 | return ConstantInt::get(V->getType(), ~(*C)); |
| 5533 | |
| 5534 | return nullptr; |
| 5535 | } |
| 5536 | |
| 5537 | /// Match non-obvious integer minimum and maximum sequences. |
| 5538 | static SelectPatternResult matchMinMax(CmpInst::Predicate Pred, |
| 5539 | Value *CmpLHS, Value *CmpRHS, |
| 5540 | Value *TrueVal, Value *FalseVal, |
| 5541 | Value *&LHS, Value *&RHS, |
| 5542 | unsigned Depth) { |
| 5543 | // Assume success. If there's no match, callers should not use these anyway. |
| 5544 | LHS = TrueVal; |
| 5545 | RHS = FalseVal; |
| 5546 | |
| 5547 | SelectPatternResult SPR = matchClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal); |
| 5548 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) |
| 5549 | return SPR; |
| 5550 | |
| 5551 | SPR = matchMinMaxOfMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, Depth); |
| 5552 | if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN) |
| 5553 | return SPR; |
| 5554 | |
| 5555 | // Look through 'not' ops to find disguised min/max. |
| 5556 | // (X > Y) ? ~X : ~Y ==> (~X < ~Y) ? ~X : ~Y ==> MIN(~X, ~Y) |
| 5557 | // (X < Y) ? ~X : ~Y ==> (~X > ~Y) ? ~X : ~Y ==> MAX(~X, ~Y) |
| 5558 | if (CmpLHS == getNotValue(TrueVal) && CmpRHS == getNotValue(FalseVal)) { |
| 5559 | switch (Pred) { |
| 5560 | case CmpInst::ICMP_SGT: return {SPF_SMIN, SPNB_NA, false}; |
| 5561 | case CmpInst::ICMP_SLT: return {SPF_SMAX, SPNB_NA, false}; |
| 5562 | case CmpInst::ICMP_UGT: return {SPF_UMIN, SPNB_NA, false}; |
| 5563 | case CmpInst::ICMP_ULT: return {SPF_UMAX, SPNB_NA, false}; |
| 5564 | default: break; |
| 5565 | } |
| 5566 | } |
| 5567 | |
| 5568 | // (X > Y) ? ~Y : ~X ==> (~X < ~Y) ? ~Y : ~X ==> MAX(~Y, ~X) |
| 5569 | // (X < Y) ? ~Y : ~X ==> (~X > ~Y) ? ~Y : ~X ==> MIN(~Y, ~X) |
| 5570 | if (CmpLHS == getNotValue(FalseVal) && CmpRHS == getNotValue(TrueVal)) { |
| 5571 | switch (Pred) { |
| 5572 | case CmpInst::ICMP_SGT: return {SPF_SMAX, SPNB_NA, false}; |
| 5573 | case CmpInst::ICMP_SLT: return {SPF_SMIN, SPNB_NA, false}; |
| 5574 | case CmpInst::ICMP_UGT: return {SPF_UMAX, SPNB_NA, false}; |
| 5575 | case CmpInst::ICMP_ULT: return {SPF_UMIN, SPNB_NA, false}; |
| 5576 | default: break; |
| 5577 | } |
| 5578 | } |
| 5579 | |
| 5580 | if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT) |
| 5581 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5582 | |
| 5583 | // Z = X -nsw Y |
| 5584 | // (X >s Y) ? 0 : Z ==> (Z >s 0) ? 0 : Z ==> SMIN(Z, 0) |
| 5585 | // (X <s Y) ? 0 : Z ==> (Z <s 0) ? 0 : Z ==> SMAX(Z, 0) |
| 5586 | if (match(TrueVal, m_Zero()) && |
| 5587 | match(FalseVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS)))) |
| 5588 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false}; |
| 5589 | |
| 5590 | // Z = X -nsw Y |
| 5591 | // (X >s Y) ? Z : 0 ==> (Z >s 0) ? Z : 0 ==> SMAX(Z, 0) |
| 5592 | // (X <s Y) ? Z : 0 ==> (Z <s 0) ? Z : 0 ==> SMIN(Z, 0) |
| 5593 | if (match(FalseVal, m_Zero()) && |
| 5594 | match(TrueVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS)))) |
| 5595 | return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false}; |
| 5596 | |
| 5597 | const APInt *C1; |
| 5598 | if (!match(CmpRHS, m_APInt(C1))) |
| 5599 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5600 | |
| 5601 | // An unsigned min/max can be written with a signed compare. |
| 5602 | const APInt *C2; |
| 5603 | if ((CmpLHS == TrueVal && match(FalseVal, m_APInt(C2))) || |
| 5604 | (CmpLHS == FalseVal && match(TrueVal, m_APInt(C2)))) { |
| 5605 | // Is the sign bit set? |
| 5606 | // (X <s 0) ? X : MAXVAL ==> (X >u MAXVAL) ? X : MAXVAL ==> UMAX |
| 5607 | // (X <s 0) ? MAXVAL : X ==> (X >u MAXVAL) ? MAXVAL : X ==> UMIN |
| 5608 | if (Pred == CmpInst::ICMP_SLT && C1->isNullValue() && |
| 5609 | C2->isMaxSignedValue()) |
| 5610 | return {CmpLHS == TrueVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; |
| 5611 | |
| 5612 | // Is the sign bit clear? |
| 5613 | // (X >s -1) ? MINVAL : X ==> (X <u MINVAL) ? MINVAL : X ==> UMAX |
| 5614 | // (X >s -1) ? X : MINVAL ==> (X <u MINVAL) ? X : MINVAL ==> UMIN |
| 5615 | if (Pred == CmpInst::ICMP_SGT && C1->isAllOnesValue() && |
| 5616 | C2->isMinSignedValue()) |
| 5617 | return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false}; |
| 5618 | } |
| 5619 | |
| 5620 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5621 | } |
| 5622 | |
| 5623 | bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW) { |
| 5624 | assert(X && Y && "Invalid operand")((X && Y && "Invalid operand") ? static_cast< void> (0) : __assert_fail ("X && Y && \"Invalid operand\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 5624, __PRETTY_FUNCTION__)); |
| 5625 | |
| 5626 | // X = sub (0, Y) || X = sub nsw (0, Y) |
| 5627 | if ((!NeedNSW && match(X, m_Sub(m_ZeroInt(), m_Specific(Y)))) || |
| 5628 | (NeedNSW && match(X, m_NSWSub(m_ZeroInt(), m_Specific(Y))))) |
| 5629 | return true; |
| 5630 | |
| 5631 | // Y = sub (0, X) || Y = sub nsw (0, X) |
| 5632 | if ((!NeedNSW && match(Y, m_Sub(m_ZeroInt(), m_Specific(X)))) || |
| 5633 | (NeedNSW && match(Y, m_NSWSub(m_ZeroInt(), m_Specific(X))))) |
| 5634 | return true; |
| 5635 | |
| 5636 | // X = sub (A, B), Y = sub (B, A) || X = sub nsw (A, B), Y = sub nsw (B, A) |
| 5637 | Value *A, *B; |
| 5638 | return (!NeedNSW && (match(X, m_Sub(m_Value(A), m_Value(B))) && |
| 5639 | match(Y, m_Sub(m_Specific(B), m_Specific(A))))) || |
| 5640 | (NeedNSW && (match(X, m_NSWSub(m_Value(A), m_Value(B))) && |
| 5641 | match(Y, m_NSWSub(m_Specific(B), m_Specific(A))))); |
| 5642 | } |
| 5643 | |
| 5644 | static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred, |
| 5645 | FastMathFlags FMF, |
| 5646 | Value *CmpLHS, Value *CmpRHS, |
| 5647 | Value *TrueVal, Value *FalseVal, |
| 5648 | Value *&LHS, Value *&RHS, |
| 5649 | unsigned Depth) { |
| 5650 | if (CmpInst::isFPPredicate(Pred)) { |
| 5651 | // IEEE-754 ignores the sign of 0.0 in comparisons. So if the select has one |
| 5652 | // 0.0 operand, set the compare's 0.0 operands to that same value for the |
| 5653 | // purpose of identifying min/max. Disregard vector constants with undefined |
| 5654 | // elements because those can not be back-propagated for analysis. |
| 5655 | Value *OutputZeroVal = nullptr; |
| 5656 | if (match(TrueVal, m_AnyZeroFP()) && !match(FalseVal, m_AnyZeroFP()) && |
| 5657 | !cast<Constant>(TrueVal)->containsUndefOrPoisonElement()) |
| 5658 | OutputZeroVal = TrueVal; |
| 5659 | else if (match(FalseVal, m_AnyZeroFP()) && !match(TrueVal, m_AnyZeroFP()) && |
| 5660 | !cast<Constant>(FalseVal)->containsUndefOrPoisonElement()) |
| 5661 | OutputZeroVal = FalseVal; |
| 5662 | |
| 5663 | if (OutputZeroVal) { |
| 5664 | if (match(CmpLHS, m_AnyZeroFP())) |
| 5665 | CmpLHS = OutputZeroVal; |
| 5666 | if (match(CmpRHS, m_AnyZeroFP())) |
| 5667 | CmpRHS = OutputZeroVal; |
| 5668 | } |
| 5669 | } |
| 5670 | |
| 5671 | LHS = CmpLHS; |
| 5672 | RHS = CmpRHS; |
| 5673 | |
| 5674 | // Signed zero may return inconsistent results between implementations. |
| 5675 | // (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0 |
| 5676 | // minNum(0.0, -0.0) // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1) |
| 5677 | // Therefore, we behave conservatively and only proceed if at least one of the |
| 5678 | // operands is known to not be zero or if we don't care about signed zero. |
| 5679 | switch (Pred) { |
| 5680 | default: break; |
| 5681 | // FIXME: Include OGT/OLT/UGT/ULT. |
| 5682 | case CmpInst::FCMP_OGE: case CmpInst::FCMP_OLE: |
| 5683 | case CmpInst::FCMP_UGE: case CmpInst::FCMP_ULE: |
| 5684 | if (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && |
| 5685 | !isKnownNonZero(CmpRHS)) |
| 5686 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5687 | } |
| 5688 | |
| 5689 | SelectPatternNaNBehavior NaNBehavior = SPNB_NA; |
| 5690 | bool Ordered = false; |
| 5691 | |
| 5692 | // When given one NaN and one non-NaN input: |
| 5693 | // - maxnum/minnum (C99 fmaxf()/fminf()) return the non-NaN input. |
| 5694 | // - A simple C99 (a < b ? a : b) construction will return 'b' (as the |
| 5695 | // ordered comparison fails), which could be NaN or non-NaN. |
| 5696 | // so here we discover exactly what NaN behavior is required/accepted. |
| 5697 | if (CmpInst::isFPPredicate(Pred)) { |
| 5698 | bool LHSSafe = isKnownNonNaN(CmpLHS, FMF); |
| 5699 | bool RHSSafe = isKnownNonNaN(CmpRHS, FMF); |
| 5700 | |
| 5701 | if (LHSSafe && RHSSafe) { |
| 5702 | // Both operands are known non-NaN. |
| 5703 | NaNBehavior = SPNB_RETURNS_ANY; |
| 5704 | } else if (CmpInst::isOrdered(Pred)) { |
| 5705 | // An ordered comparison will return false when given a NaN, so it |
| 5706 | // returns the RHS. |
| 5707 | Ordered = true; |
| 5708 | if (LHSSafe) |
| 5709 | // LHS is non-NaN, so if RHS is NaN then NaN will be returned. |
| 5710 | NaNBehavior = SPNB_RETURNS_NAN; |
| 5711 | else if (RHSSafe) |
| 5712 | NaNBehavior = SPNB_RETURNS_OTHER; |
| 5713 | else |
| 5714 | // Completely unsafe. |
| 5715 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5716 | } else { |
| 5717 | Ordered = false; |
| 5718 | // An unordered comparison will return true when given a NaN, so it |
| 5719 | // returns the LHS. |
| 5720 | if (LHSSafe) |
| 5721 | // LHS is non-NaN, so if RHS is NaN then non-NaN will be returned. |
| 5722 | NaNBehavior = SPNB_RETURNS_OTHER; |
| 5723 | else if (RHSSafe) |
| 5724 | NaNBehavior = SPNB_RETURNS_NAN; |
| 5725 | else |
| 5726 | // Completely unsafe. |
| 5727 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5728 | } |
| 5729 | } |
| 5730 | |
| 5731 | if (TrueVal == CmpRHS && FalseVal == CmpLHS) { |
| 5732 | std::swap(CmpLHS, CmpRHS); |
| 5733 | Pred = CmpInst::getSwappedPredicate(Pred); |
| 5734 | if (NaNBehavior == SPNB_RETURNS_NAN) |
| 5735 | NaNBehavior = SPNB_RETURNS_OTHER; |
| 5736 | else if (NaNBehavior == SPNB_RETURNS_OTHER) |
| 5737 | NaNBehavior = SPNB_RETURNS_NAN; |
| 5738 | Ordered = !Ordered; |
| 5739 | } |
| 5740 | |
| 5741 | // ([if]cmp X, Y) ? X : Y |
| 5742 | if (TrueVal == CmpLHS && FalseVal == CmpRHS) { |
| 5743 | switch (Pred) { |
| 5744 | default: return {SPF_UNKNOWN, SPNB_NA, false}; // Equality. |
| 5745 | case ICmpInst::ICMP_UGT: |
| 5746 | case ICmpInst::ICMP_UGE: return {SPF_UMAX, SPNB_NA, false}; |
| 5747 | case ICmpInst::ICMP_SGT: |
| 5748 | case ICmpInst::ICMP_SGE: return {SPF_SMAX, SPNB_NA, false}; |
| 5749 | case ICmpInst::ICMP_ULT: |
| 5750 | case ICmpInst::ICMP_ULE: return {SPF_UMIN, SPNB_NA, false}; |
| 5751 | case ICmpInst::ICMP_SLT: |
| 5752 | case ICmpInst::ICMP_SLE: return {SPF_SMIN, SPNB_NA, false}; |
| 5753 | case FCmpInst::FCMP_UGT: |
| 5754 | case FCmpInst::FCMP_UGE: |
| 5755 | case FCmpInst::FCMP_OGT: |
| 5756 | case FCmpInst::FCMP_OGE: return {SPF_FMAXNUM, NaNBehavior, Ordered}; |
| 5757 | case FCmpInst::FCMP_ULT: |
| 5758 | case FCmpInst::FCMP_ULE: |
| 5759 | case FCmpInst::FCMP_OLT: |
| 5760 | case FCmpInst::FCMP_OLE: return {SPF_FMINNUM, NaNBehavior, Ordered}; |
| 5761 | } |
| 5762 | } |
| 5763 | |
| 5764 | if (isKnownNegation(TrueVal, FalseVal)) { |
| 5765 | // Sign-extending LHS does not change its sign, so TrueVal/FalseVal can |
| 5766 | // match against either LHS or sext(LHS). |
| 5767 | auto MaybeSExtCmpLHS = |
| 5768 | m_CombineOr(m_Specific(CmpLHS), m_SExt(m_Specific(CmpLHS))); |
| 5769 | auto ZeroOrAllOnes = m_CombineOr(m_ZeroInt(), m_AllOnes()); |
| 5770 | auto ZeroOrOne = m_CombineOr(m_ZeroInt(), m_One()); |
| 5771 | if (match(TrueVal, MaybeSExtCmpLHS)) { |
| 5772 | // Set the return values. If the compare uses the negated value (-X >s 0), |
| 5773 | // swap the return values because the negated value is always 'RHS'. |
| 5774 | LHS = TrueVal; |
| 5775 | RHS = FalseVal; |
| 5776 | if (match(CmpLHS, m_Neg(m_Specific(FalseVal)))) |
| 5777 | std::swap(LHS, RHS); |
| 5778 | |
| 5779 | // (X >s 0) ? X : -X or (X >s -1) ? X : -X --> ABS(X) |
| 5780 | // (-X >s 0) ? -X : X or (-X >s -1) ? -X : X --> ABS(X) |
| 5781 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) |
| 5782 | return {SPF_ABS, SPNB_NA, false}; |
| 5783 | |
| 5784 | // (X >=s 0) ? X : -X or (X >=s 1) ? X : -X --> ABS(X) |
| 5785 | if (Pred == ICmpInst::ICMP_SGE && match(CmpRHS, ZeroOrOne)) |
| 5786 | return {SPF_ABS, SPNB_NA, false}; |
| 5787 | |
| 5788 | // (X <s 0) ? X : -X or (X <s 1) ? X : -X --> NABS(X) |
| 5789 | // (-X <s 0) ? -X : X or (-X <s 1) ? -X : X --> NABS(X) |
| 5790 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) |
| 5791 | return {SPF_NABS, SPNB_NA, false}; |
| 5792 | } |
| 5793 | else if (match(FalseVal, MaybeSExtCmpLHS)) { |
| 5794 | // Set the return values. If the compare uses the negated value (-X >s 0), |
| 5795 | // swap the return values because the negated value is always 'RHS'. |
| 5796 | LHS = FalseVal; |
| 5797 | RHS = TrueVal; |
| 5798 | if (match(CmpLHS, m_Neg(m_Specific(TrueVal)))) |
| 5799 | std::swap(LHS, RHS); |
| 5800 | |
| 5801 | // (X >s 0) ? -X : X or (X >s -1) ? -X : X --> NABS(X) |
| 5802 | // (-X >s 0) ? X : -X or (-X >s -1) ? X : -X --> NABS(X) |
| 5803 | if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes)) |
| 5804 | return {SPF_NABS, SPNB_NA, false}; |
| 5805 | |
| 5806 | // (X <s 0) ? -X : X or (X <s 1) ? -X : X --> ABS(X) |
| 5807 | // (-X <s 0) ? X : -X or (-X <s 1) ? X : -X --> ABS(X) |
| 5808 | if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne)) |
| 5809 | return {SPF_ABS, SPNB_NA, false}; |
| 5810 | } |
| 5811 | } |
| 5812 | |
| 5813 | if (CmpInst::isIntPredicate(Pred)) |
| 5814 | return matchMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS, Depth); |
| 5815 | |
| 5816 | // According to (IEEE 754-2008 5.3.1), minNum(0.0, -0.0) and similar |
| 5817 | // may return either -0.0 or 0.0, so fcmp/select pair has stricter |
| 5818 | // semantics than minNum. Be conservative in such case. |
| 5819 | if (NaNBehavior != SPNB_RETURNS_ANY || |
| 5820 | (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && |
| 5821 | !isKnownNonZero(CmpRHS))) |
| 5822 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5823 | |
| 5824 | return matchFastFloatClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS); |
| 5825 | } |
| 5826 | |
| 5827 | /// Helps to match a select pattern in case of a type mismatch. |
| 5828 | /// |
| 5829 | /// The function processes the case when type of true and false values of a |
| 5830 | /// select instruction differs from type of the cmp instruction operands because |
| 5831 | /// of a cast instruction. The function checks if it is legal to move the cast |
| 5832 | /// operation after "select". If yes, it returns the new second value of |
| 5833 | /// "select" (with the assumption that cast is moved): |
| 5834 | /// 1. As operand of cast instruction when both values of "select" are same cast |
| 5835 | /// instructions. |
| 5836 | /// 2. As restored constant (by applying reverse cast operation) when the first |
| 5837 | /// value of the "select" is a cast operation and the second value is a |
| 5838 | /// constant. |
| 5839 | /// NOTE: We return only the new second value because the first value could be |
| 5840 | /// accessed as operand of cast instruction. |
| 5841 | static Value *lookThroughCast(CmpInst *CmpI, Value *V1, Value *V2, |
| 5842 | Instruction::CastOps *CastOp) { |
| 5843 | auto *Cast1 = dyn_cast<CastInst>(V1); |
| 5844 | if (!Cast1) |
| 5845 | return nullptr; |
| 5846 | |
| 5847 | *CastOp = Cast1->getOpcode(); |
| 5848 | Type *SrcTy = Cast1->getSrcTy(); |
| 5849 | if (auto *Cast2 = dyn_cast<CastInst>(V2)) { |
| 5850 | // If V1 and V2 are both the same cast from the same type, look through V1. |
| 5851 | if (*CastOp == Cast2->getOpcode() && SrcTy == Cast2->getSrcTy()) |
| 5852 | return Cast2->getOperand(0); |
| 5853 | return nullptr; |
| 5854 | } |
| 5855 | |
| 5856 | auto *C = dyn_cast<Constant>(V2); |
| 5857 | if (!C) |
| 5858 | return nullptr; |
| 5859 | |
| 5860 | Constant *CastedTo = nullptr; |
| 5861 | switch (*CastOp) { |
| 5862 | case Instruction::ZExt: |
| 5863 | if (CmpI->isUnsigned()) |
| 5864 | CastedTo = ConstantExpr::getTrunc(C, SrcTy); |
| 5865 | break; |
| 5866 | case Instruction::SExt: |
| 5867 | if (CmpI->isSigned()) |
| 5868 | CastedTo = ConstantExpr::getTrunc(C, SrcTy, true); |
| 5869 | break; |
| 5870 | case Instruction::Trunc: |
| 5871 | Constant *CmpConst; |
| 5872 | if (match(CmpI->getOperand(1), m_Constant(CmpConst)) && |
| 5873 | CmpConst->getType() == SrcTy) { |
| 5874 | // Here we have the following case: |
| 5875 | // |
| 5876 | // %cond = cmp iN %x, CmpConst |
| 5877 | // %tr = trunc iN %x to iK |
| 5878 | // %narrowsel = select i1 %cond, iK %t, iK C |
| 5879 | // |
| 5880 | // We can always move trunc after select operation: |
| 5881 | // |
| 5882 | // %cond = cmp iN %x, CmpConst |
| 5883 | // %widesel = select i1 %cond, iN %x, iN CmpConst |
| 5884 | // %tr = trunc iN %widesel to iK |
| 5885 | // |
| 5886 | // Note that C could be extended in any way because we don't care about |
| 5887 | // upper bits after truncation. It can't be abs pattern, because it would |
| 5888 | // look like: |
| 5889 | // |
| 5890 | // select i1 %cond, x, -x. |
| 5891 | // |
| 5892 | // So only min/max pattern could be matched. Such match requires widened C |
| 5893 | // == CmpConst. That is why set widened C = CmpConst, condition trunc |
| 5894 | // CmpConst == C is checked below. |
| 5895 | CastedTo = CmpConst; |
| 5896 | } else { |
| 5897 | CastedTo = ConstantExpr::getIntegerCast(C, SrcTy, CmpI->isSigned()); |
| 5898 | } |
| 5899 | break; |
| 5900 | case Instruction::FPTrunc: |
| 5901 | CastedTo = ConstantExpr::getFPExtend(C, SrcTy, true); |
| 5902 | break; |
| 5903 | case Instruction::FPExt: |
| 5904 | CastedTo = ConstantExpr::getFPTrunc(C, SrcTy, true); |
| 5905 | break; |
| 5906 | case Instruction::FPToUI: |
| 5907 | CastedTo = ConstantExpr::getUIToFP(C, SrcTy, true); |
| 5908 | break; |
| 5909 | case Instruction::FPToSI: |
| 5910 | CastedTo = ConstantExpr::getSIToFP(C, SrcTy, true); |
| 5911 | break; |
| 5912 | case Instruction::UIToFP: |
| 5913 | CastedTo = ConstantExpr::getFPToUI(C, SrcTy, true); |
| 5914 | break; |
| 5915 | case Instruction::SIToFP: |
| 5916 | CastedTo = ConstantExpr::getFPToSI(C, SrcTy, true); |
| 5917 | break; |
| 5918 | default: |
| 5919 | break; |
| 5920 | } |
| 5921 | |
| 5922 | if (!CastedTo) |
| 5923 | return nullptr; |
| 5924 | |
| 5925 | // Make sure the cast doesn't lose any information. |
| 5926 | Constant *CastedBack = |
| 5927 | ConstantExpr::getCast(*CastOp, CastedTo, C->getType(), true); |
| 5928 | if (CastedBack != C) |
| 5929 | return nullptr; |
| 5930 | |
| 5931 | return CastedTo; |
| 5932 | } |
| 5933 | |
| 5934 | SelectPatternResult llvm::matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, |
| 5935 | Instruction::CastOps *CastOp, |
| 5936 | unsigned Depth) { |
| 5937 | if (Depth >= MaxAnalysisRecursionDepth) |
| 5938 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5939 | |
| 5940 | SelectInst *SI = dyn_cast<SelectInst>(V); |
| 5941 | if (!SI) return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5942 | |
| 5943 | CmpInst *CmpI = dyn_cast<CmpInst>(SI->getCondition()); |
| 5944 | if (!CmpI) return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5945 | |
| 5946 | Value *TrueVal = SI->getTrueValue(); |
| 5947 | Value *FalseVal = SI->getFalseValue(); |
| 5948 | |
| 5949 | return llvm::matchDecomposedSelectPattern(CmpI, TrueVal, FalseVal, LHS, RHS, |
| 5950 | CastOp, Depth); |
| 5951 | } |
| 5952 | |
| 5953 | SelectPatternResult llvm::matchDecomposedSelectPattern( |
| 5954 | CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS, |
| 5955 | Instruction::CastOps *CastOp, unsigned Depth) { |
| 5956 | CmpInst::Predicate Pred = CmpI->getPredicate(); |
| 5957 | Value *CmpLHS = CmpI->getOperand(0); |
| 5958 | Value *CmpRHS = CmpI->getOperand(1); |
| 5959 | FastMathFlags FMF; |
| 5960 | if (isa<FPMathOperator>(CmpI)) |
| 5961 | FMF = CmpI->getFastMathFlags(); |
| 5962 | |
| 5963 | // Bail out early. |
| 5964 | if (CmpI->isEquality()) |
| 5965 | return {SPF_UNKNOWN, SPNB_NA, false}; |
| 5966 | |
| 5967 | // Deal with type mismatches. |
| 5968 | if (CastOp && CmpLHS->getType() != TrueVal->getType()) { |
| 5969 | if (Value *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp)) { |
| 5970 | // If this is a potential fmin/fmax with a cast to integer, then ignore |
| 5971 | // -0.0 because there is no corresponding integer value. |
| 5972 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) |
| 5973 | FMF.setNoSignedZeros(); |
| 5974 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, |
| 5975 | cast<CastInst>(TrueVal)->getOperand(0), C, |
| 5976 | LHS, RHS, Depth); |
| 5977 | } |
| 5978 | if (Value *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp)) { |
| 5979 | // If this is a potential fmin/fmax with a cast to integer, then ignore |
| 5980 | // -0.0 because there is no corresponding integer value. |
| 5981 | if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) |
| 5982 | FMF.setNoSignedZeros(); |
| 5983 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, |
| 5984 | C, cast<CastInst>(FalseVal)->getOperand(0), |
| 5985 | LHS, RHS, Depth); |
| 5986 | } |
| 5987 | } |
| 5988 | return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, TrueVal, FalseVal, |
| 5989 | LHS, RHS, Depth); |
| 5990 | } |
| 5991 | |
| 5992 | CmpInst::Predicate llvm::getMinMaxPred(SelectPatternFlavor SPF, bool Ordered) { |
| 5993 | if (SPF == SPF_SMIN) return ICmpInst::ICMP_SLT; |
| 5994 | if (SPF == SPF_UMIN) return ICmpInst::ICMP_ULT; |
| 5995 | if (SPF == SPF_SMAX) return ICmpInst::ICMP_SGT; |
| 5996 | if (SPF == SPF_UMAX) return ICmpInst::ICMP_UGT; |
| 5997 | if (SPF == SPF_FMINNUM) |
| 5998 | return Ordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; |
| 5999 | if (SPF == SPF_FMAXNUM) |
| 6000 | return Ordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; |
| 6001 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6001); |
| 6002 | } |
| 6003 | |
| 6004 | SelectPatternFlavor llvm::getInverseMinMaxFlavor(SelectPatternFlavor SPF) { |
| 6005 | if (SPF == SPF_SMIN) return SPF_SMAX; |
| 6006 | if (SPF == SPF_UMIN) return SPF_UMAX; |
| 6007 | if (SPF == SPF_SMAX) return SPF_SMIN; |
| 6008 | if (SPF == SPF_UMAX) return SPF_UMIN; |
| 6009 | llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6009); |
| 6010 | } |
| 6011 | |
| 6012 | CmpInst::Predicate llvm::getInverseMinMaxPred(SelectPatternFlavor SPF) { |
| 6013 | return getMinMaxPred(getInverseMinMaxFlavor(SPF)); |
| 6014 | } |
| 6015 | |
| 6016 | std::pair<Intrinsic::ID, bool> |
| 6017 | llvm::canConvertToMinOrMaxIntrinsic(ArrayRef<Value *> VL) { |
| 6018 | // Check if VL contains select instructions that can be folded into a min/max |
| 6019 | // vector intrinsic and return the intrinsic if it is possible. |
| 6020 | // TODO: Support floating point min/max. |
| 6021 | bool AllCmpSingleUse = true; |
| 6022 | SelectPatternResult SelectPattern; |
| 6023 | SelectPattern.Flavor = SPF_UNKNOWN; |
| 6024 | if (all_of(VL, [&SelectPattern, &AllCmpSingleUse](Value *I) { |
| 6025 | Value *LHS, *RHS; |
| 6026 | auto CurrentPattern = matchSelectPattern(I, LHS, RHS); |
| 6027 | if (!SelectPatternResult::isMinOrMax(CurrentPattern.Flavor) || |
| 6028 | CurrentPattern.Flavor == SPF_FMINNUM || |
| 6029 | CurrentPattern.Flavor == SPF_FMAXNUM || |
| 6030 | !I->getType()->isIntOrIntVectorTy()) |
| 6031 | return false; |
| 6032 | if (SelectPattern.Flavor != SPF_UNKNOWN && |
| 6033 | SelectPattern.Flavor != CurrentPattern.Flavor) |
| 6034 | return false; |
| 6035 | SelectPattern = CurrentPattern; |
| 6036 | AllCmpSingleUse &= |
| 6037 | match(I, m_Select(m_OneUse(m_Value()), m_Value(), m_Value())); |
| 6038 | return true; |
| 6039 | })) { |
| 6040 | switch (SelectPattern.Flavor) { |
| 6041 | case SPF_SMIN: |
| 6042 | return {Intrinsic::smin, AllCmpSingleUse}; |
| 6043 | case SPF_UMIN: |
| 6044 | return {Intrinsic::umin, AllCmpSingleUse}; |
| 6045 | case SPF_SMAX: |
| 6046 | return {Intrinsic::smax, AllCmpSingleUse}; |
| 6047 | case SPF_UMAX: |
| 6048 | return {Intrinsic::umax, AllCmpSingleUse}; |
| 6049 | default: |
| 6050 | llvm_unreachable("unexpected select pattern flavor")::llvm::llvm_unreachable_internal("unexpected select pattern flavor" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6050); |
| 6051 | } |
| 6052 | } |
| 6053 | return {Intrinsic::not_intrinsic, false}; |
| 6054 | } |
| 6055 | |
| 6056 | /// Return true if "icmp Pred LHS RHS" is always true. |
| 6057 | static bool isTruePredicate(CmpInst::Predicate Pred, const Value *LHS, |
| 6058 | const Value *RHS, const DataLayout &DL, |
| 6059 | unsigned Depth) { |
| 6060 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6060, __PRETTY_FUNCTION__)); |
| 6061 | if (ICmpInst::isTrueWhenEqual(Pred) && LHS == RHS) |
| 6062 | return true; |
| 6063 | |
| 6064 | switch (Pred) { |
| 6065 | default: |
| 6066 | return false; |
| 6067 | |
| 6068 | case CmpInst::ICMP_SLE: { |
| 6069 | const APInt *C; |
| 6070 | |
| 6071 | // LHS s<= LHS +_{nsw} C if C >= 0 |
| 6072 | if (match(RHS, m_NSWAdd(m_Specific(LHS), m_APInt(C)))) |
| 6073 | return !C->isNegative(); |
| 6074 | return false; |
| 6075 | } |
| 6076 | |
| 6077 | case CmpInst::ICMP_ULE: { |
| 6078 | const APInt *C; |
| 6079 | |
| 6080 | // LHS u<= LHS +_{nuw} C for any C |
| 6081 | if (match(RHS, m_NUWAdd(m_Specific(LHS), m_APInt(C)))) |
| 6082 | return true; |
| 6083 | |
| 6084 | // Match A to (X +_{nuw} CA) and B to (X +_{nuw} CB) |
| 6085 | auto MatchNUWAddsToSameValue = [&](const Value *A, const Value *B, |
| 6086 | const Value *&X, |
| 6087 | const APInt *&CA, const APInt *&CB) { |
| 6088 | if (match(A, m_NUWAdd(m_Value(X), m_APInt(CA))) && |
| 6089 | match(B, m_NUWAdd(m_Specific(X), m_APInt(CB)))) |
| 6090 | return true; |
| 6091 | |
| 6092 | // If X & C == 0 then (X | C) == X +_{nuw} C |
| 6093 | if (match(A, m_Or(m_Value(X), m_APInt(CA))) && |
| 6094 | match(B, m_Or(m_Specific(X), m_APInt(CB)))) { |
| 6095 | KnownBits Known(CA->getBitWidth()); |
| 6096 | computeKnownBits(X, Known, DL, Depth + 1, /*AC*/ nullptr, |
| 6097 | /*CxtI*/ nullptr, /*DT*/ nullptr); |
| 6098 | if (CA->isSubsetOf(Known.Zero) && CB->isSubsetOf(Known.Zero)) |
| 6099 | return true; |
| 6100 | } |
| 6101 | |
| 6102 | return false; |
| 6103 | }; |
| 6104 | |
| 6105 | const Value *X; |
| 6106 | const APInt *CLHS, *CRHS; |
| 6107 | if (MatchNUWAddsToSameValue(LHS, RHS, X, CLHS, CRHS)) |
| 6108 | return CLHS->ule(*CRHS); |
| 6109 | |
| 6110 | return false; |
| 6111 | } |
| 6112 | } |
| 6113 | } |
| 6114 | |
| 6115 | /// Return true if "icmp Pred BLHS BRHS" is true whenever "icmp Pred |
| 6116 | /// ALHS ARHS" is true. Otherwise, return None. |
| 6117 | static Optional<bool> |
| 6118 | isImpliedCondOperands(CmpInst::Predicate Pred, const Value *ALHS, |
| 6119 | const Value *ARHS, const Value *BLHS, const Value *BRHS, |
| 6120 | const DataLayout &DL, unsigned Depth) { |
| 6121 | switch (Pred) { |
| 6122 | default: |
| 6123 | return None; |
| 6124 | |
| 6125 | case CmpInst::ICMP_SLT: |
| 6126 | case CmpInst::ICMP_SLE: |
| 6127 | if (isTruePredicate(CmpInst::ICMP_SLE, BLHS, ALHS, DL, Depth) && |
| 6128 | isTruePredicate(CmpInst::ICMP_SLE, ARHS, BRHS, DL, Depth)) |
| 6129 | return true; |
| 6130 | return None; |
| 6131 | |
| 6132 | case CmpInst::ICMP_ULT: |
| 6133 | case CmpInst::ICMP_ULE: |
| 6134 | if (isTruePredicate(CmpInst::ICMP_ULE, BLHS, ALHS, DL, Depth) && |
| 6135 | isTruePredicate(CmpInst::ICMP_ULE, ARHS, BRHS, DL, Depth)) |
| 6136 | return true; |
| 6137 | return None; |
| 6138 | } |
| 6139 | } |
| 6140 | |
| 6141 | /// Return true if the operands of the two compares match. IsSwappedOps is true |
| 6142 | /// when the operands match, but are swapped. |
| 6143 | static bool isMatchingOps(const Value *ALHS, const Value *ARHS, |
| 6144 | const Value *BLHS, const Value *BRHS, |
| 6145 | bool &IsSwappedOps) { |
| 6146 | |
| 6147 | bool IsMatchingOps = (ALHS == BLHS && ARHS == BRHS); |
| 6148 | IsSwappedOps = (ALHS == BRHS && ARHS == BLHS); |
| 6149 | return IsMatchingOps || IsSwappedOps; |
| 6150 | } |
| 6151 | |
| 6152 | /// Return true if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is true. |
| 6153 | /// Return false if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is false. |
| 6154 | /// Otherwise, return None if we can't infer anything. |
| 6155 | static Optional<bool> isImpliedCondMatchingOperands(CmpInst::Predicate APred, |
| 6156 | CmpInst::Predicate BPred, |
| 6157 | bool AreSwappedOps) { |
| 6158 | // Canonicalize the predicate as if the operands were not commuted. |
| 6159 | if (AreSwappedOps) |
| 6160 | BPred = ICmpInst::getSwappedPredicate(BPred); |
| 6161 | |
| 6162 | if (CmpInst::isImpliedTrueByMatchingCmp(APred, BPred)) |
| 6163 | return true; |
| 6164 | if (CmpInst::isImpliedFalseByMatchingCmp(APred, BPred)) |
| 6165 | return false; |
| 6166 | |
| 6167 | return None; |
| 6168 | } |
| 6169 | |
| 6170 | /// Return true if "icmp APred X, C1" implies "icmp BPred X, C2" is true. |
| 6171 | /// Return false if "icmp APred X, C1" implies "icmp BPred X, C2" is false. |
| 6172 | /// Otherwise, return None if we can't infer anything. |
| 6173 | static Optional<bool> |
| 6174 | isImpliedCondMatchingImmOperands(CmpInst::Predicate APred, |
| 6175 | const ConstantInt *C1, |
| 6176 | CmpInst::Predicate BPred, |
| 6177 | const ConstantInt *C2) { |
| 6178 | ConstantRange DomCR = |
| 6179 | ConstantRange::makeExactICmpRegion(APred, C1->getValue()); |
| 6180 | ConstantRange CR = |
| 6181 | ConstantRange::makeAllowedICmpRegion(BPred, C2->getValue()); |
| 6182 | ConstantRange Intersection = DomCR.intersectWith(CR); |
| 6183 | ConstantRange Difference = DomCR.difference(CR); |
| 6184 | if (Intersection.isEmptySet()) |
| 6185 | return false; |
| 6186 | if (Difference.isEmptySet()) |
| 6187 | return true; |
| 6188 | return None; |
| 6189 | } |
| 6190 | |
| 6191 | /// Return true if LHS implies RHS is true. Return false if LHS implies RHS is |
| 6192 | /// false. Otherwise, return None if we can't infer anything. |
| 6193 | static Optional<bool> isImpliedCondICmps(const ICmpInst *LHS, |
| 6194 | CmpInst::Predicate BPred, |
| 6195 | const Value *BLHS, const Value *BRHS, |
| 6196 | const DataLayout &DL, bool LHSIsTrue, |
| 6197 | unsigned Depth) { |
| 6198 | Value *ALHS = LHS->getOperand(0); |
| 6199 | Value *ARHS = LHS->getOperand(1); |
| 6200 | |
| 6201 | // The rest of the logic assumes the LHS condition is true. If that's not the |
| 6202 | // case, invert the predicate to make it so. |
| 6203 | CmpInst::Predicate APred = |
| 6204 | LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate(); |
| 6205 | |
| 6206 | // Can we infer anything when the two compares have matching operands? |
| 6207 | bool AreSwappedOps; |
| 6208 | if (isMatchingOps(ALHS, ARHS, BLHS, BRHS, AreSwappedOps)) { |
| 6209 | if (Optional<bool> Implication = isImpliedCondMatchingOperands( |
| 6210 | APred, BPred, AreSwappedOps)) |
| 6211 | return Implication; |
| 6212 | // No amount of additional analysis will infer the second condition, so |
| 6213 | // early exit. |
| 6214 | return None; |
| 6215 | } |
| 6216 | |
| 6217 | // Can we infer anything when the LHS operands match and the RHS operands are |
| 6218 | // constants (not necessarily matching)? |
| 6219 | if (ALHS == BLHS && isa<ConstantInt>(ARHS) && isa<ConstantInt>(BRHS)) { |
| 6220 | if (Optional<bool> Implication = isImpliedCondMatchingImmOperands( |
| 6221 | APred, cast<ConstantInt>(ARHS), BPred, cast<ConstantInt>(BRHS))) |
| 6222 | return Implication; |
| 6223 | // No amount of additional analysis will infer the second condition, so |
| 6224 | // early exit. |
| 6225 | return None; |
| 6226 | } |
| 6227 | |
| 6228 | if (APred == BPred) |
| 6229 | return isImpliedCondOperands(APred, ALHS, ARHS, BLHS, BRHS, DL, Depth); |
| 6230 | return None; |
| 6231 | } |
| 6232 | |
| 6233 | /// Return true if LHS implies RHS is true. Return false if LHS implies RHS is |
| 6234 | /// false. Otherwise, return None if we can't infer anything. We expect the |
| 6235 | /// RHS to be an icmp and the LHS to be an 'and', 'or', or a 'select' instruction. |
| 6236 | static Optional<bool> |
| 6237 | isImpliedCondAndOr(const Instruction *LHS, CmpInst::Predicate RHSPred, |
| 6238 | const Value *RHSOp0, const Value *RHSOp1, |
| 6239 | const DataLayout &DL, bool LHSIsTrue, unsigned Depth) { |
| 6240 | // The LHS must be an 'or', 'and', or a 'select' instruction. |
| 6241 | assert((LHS->getOpcode() == Instruction::And ||(((LHS->getOpcode() == Instruction::And || LHS->getOpcode () == Instruction::Or || LHS->getOpcode() == Instruction:: Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6244, __PRETTY_FUNCTION__)) |
| 6242 | LHS->getOpcode() == Instruction::Or ||(((LHS->getOpcode() == Instruction::And || LHS->getOpcode () == Instruction::Or || LHS->getOpcode() == Instruction:: Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6244, __PRETTY_FUNCTION__)) |
| 6243 | LHS->getOpcode() == Instruction::Select) &&(((LHS->getOpcode() == Instruction::And || LHS->getOpcode () == Instruction::Or || LHS->getOpcode() == Instruction:: Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6244, __PRETTY_FUNCTION__)) |
| 6244 | "Expected LHS to be 'and', 'or', or 'select'.")(((LHS->getOpcode() == Instruction::And || LHS->getOpcode () == Instruction::Or || LHS->getOpcode() == Instruction:: Select) && "Expected LHS to be 'and', 'or', or 'select'." ) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6244, __PRETTY_FUNCTION__)); |
| 6245 | |
| 6246 | assert(Depth <= MaxAnalysisRecursionDepth && "Hit recursion limit")((Depth <= MaxAnalysisRecursionDepth && "Hit recursion limit" ) ? static_cast<void> (0) : __assert_fail ("Depth <= MaxAnalysisRecursionDepth && \"Hit recursion limit\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6246, __PRETTY_FUNCTION__)); |
| 6247 | |
| 6248 | // If the result of an 'or' is false, then we know both legs of the 'or' are |
| 6249 | // false. Similarly, if the result of an 'and' is true, then we know both |
| 6250 | // legs of the 'and' are true. |
| 6251 | const Value *ALHS, *ARHS; |
| 6252 | if ((!LHSIsTrue && match(LHS, m_LogicalOr(m_Value(ALHS), m_Value(ARHS)))) || |
| 6253 | (LHSIsTrue && match(LHS, m_LogicalAnd(m_Value(ALHS), m_Value(ARHS))))) { |
| 6254 | // FIXME: Make this non-recursion. |
| 6255 | if (Optional<bool> Implication = isImpliedCondition( |
| 6256 | ALHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1)) |
| 6257 | return Implication; |
| 6258 | if (Optional<bool> Implication = isImpliedCondition( |
| 6259 | ARHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1)) |
| 6260 | return Implication; |
| 6261 | return None; |
| 6262 | } |
| 6263 | return None; |
| 6264 | } |
| 6265 | |
| 6266 | Optional<bool> |
| 6267 | llvm::isImpliedCondition(const Value *LHS, CmpInst::Predicate RHSPred, |
| 6268 | const Value *RHSOp0, const Value *RHSOp1, |
| 6269 | const DataLayout &DL, bool LHSIsTrue, unsigned Depth) { |
| 6270 | // Bail out when we hit the limit. |
| 6271 | if (Depth == MaxAnalysisRecursionDepth) |
| 6272 | return None; |
| 6273 | |
| 6274 | // A mismatch occurs when we compare a scalar cmp to a vector cmp, for |
| 6275 | // example. |
| 6276 | if (RHSOp0->getType()->isVectorTy() != LHS->getType()->isVectorTy()) |
| 6277 | return None; |
| 6278 | |
| 6279 | Type *OpTy = LHS->getType(); |
| 6280 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6280, __PRETTY_FUNCTION__)); |
| 6281 | |
| 6282 | // FIXME: Extending the code below to handle vectors. |
| 6283 | if (OpTy->isVectorTy()) |
| 6284 | return None; |
| 6285 | |
| 6286 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6286, __PRETTY_FUNCTION__)); |
| 6287 | |
| 6288 | // Both LHS and RHS are icmps. |
| 6289 | const ICmpInst *LHSCmp = dyn_cast<ICmpInst>(LHS); |
| 6290 | if (LHSCmp) |
| 6291 | return isImpliedCondICmps(LHSCmp, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, |
| 6292 | Depth); |
| 6293 | |
| 6294 | /// The LHS should be an 'or', 'and', or a 'select' instruction. We expect |
| 6295 | /// the RHS to be an icmp. |
| 6296 | /// FIXME: Add support for and/or/select on the RHS. |
| 6297 | if (const Instruction *LHSI = dyn_cast<Instruction>(LHS)) { |
| 6298 | if ((LHSI->getOpcode() == Instruction::And || |
| 6299 | LHSI->getOpcode() == Instruction::Or || |
| 6300 | LHSI->getOpcode() == Instruction::Select)) |
| 6301 | return isImpliedCondAndOr(LHSI, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, |
| 6302 | Depth); |
| 6303 | } |
| 6304 | return None; |
| 6305 | } |
| 6306 | |
| 6307 | Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS, |
| 6308 | const DataLayout &DL, bool LHSIsTrue, |
| 6309 | unsigned Depth) { |
| 6310 | // LHS ==> RHS by definition |
| 6311 | if (LHS == RHS) |
| 6312 | return LHSIsTrue; |
| 6313 | |
| 6314 | const ICmpInst *RHSCmp = dyn_cast<ICmpInst>(RHS); |
| 6315 | if (RHSCmp) |
| 6316 | return isImpliedCondition(LHS, RHSCmp->getPredicate(), |
| 6317 | RHSCmp->getOperand(0), RHSCmp->getOperand(1), DL, |
| 6318 | LHSIsTrue, Depth); |
| 6319 | return None; |
| 6320 | } |
| 6321 | |
| 6322 | // Returns a pair (Condition, ConditionIsTrue), where Condition is a branch |
| 6323 | // condition dominating ContextI or nullptr, if no condition is found. |
| 6324 | static std::pair<Value *, bool> |
| 6325 | getDomPredecessorCondition(const Instruction *ContextI) { |
| 6326 | if (!ContextI || !ContextI->getParent()) |
| 6327 | return {nullptr, false}; |
| 6328 | |
| 6329 | // TODO: This is a poor/cheap way to determine dominance. Should we use a |
| 6330 | // dominator tree (eg, from a SimplifyQuery) instead? |
| 6331 | const BasicBlock *ContextBB = ContextI->getParent(); |
| 6332 | const BasicBlock *PredBB = ContextBB->getSinglePredecessor(); |
| 6333 | if (!PredBB) |
| 6334 | return {nullptr, false}; |
| 6335 | |
| 6336 | // We need a conditional branch in the predecessor. |
| 6337 | Value *PredCond; |
| 6338 | BasicBlock *TrueBB, *FalseBB; |
| 6339 | if (!match(PredBB->getTerminator(), m_Br(m_Value(PredCond), TrueBB, FalseBB))) |
| 6340 | return {nullptr, false}; |
| 6341 | |
| 6342 | // The branch should get simplified. Don't bother simplifying this condition. |
| 6343 | if (TrueBB == FalseBB) |
| 6344 | return {nullptr, false}; |
| 6345 | |
| 6346 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6347, __PRETTY_FUNCTION__)) |
| 6347 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6347, __PRETTY_FUNCTION__)); |
| 6348 | |
| 6349 | // Is this condition implied by the predecessor condition? |
| 6350 | return {PredCond, TrueBB == ContextBB}; |
| 6351 | } |
| 6352 | |
| 6353 | Optional<bool> llvm::isImpliedByDomCondition(const Value *Cond, |
| 6354 | const Instruction *ContextI, |
| 6355 | const DataLayout &DL) { |
| 6356 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6356, __PRETTY_FUNCTION__)); |
| 6357 | auto PredCond = getDomPredecessorCondition(ContextI); |
| 6358 | if (PredCond.first) |
| 6359 | return isImpliedCondition(PredCond.first, Cond, DL, PredCond.second); |
| 6360 | return None; |
| 6361 | } |
| 6362 | |
| 6363 | Optional<bool> llvm::isImpliedByDomCondition(CmpInst::Predicate Pred, |
| 6364 | const Value *LHS, const Value *RHS, |
| 6365 | const Instruction *ContextI, |
| 6366 | const DataLayout &DL) { |
| 6367 | auto PredCond = getDomPredecessorCondition(ContextI); |
| 6368 | if (PredCond.first) |
| 6369 | return isImpliedCondition(PredCond.first, Pred, LHS, RHS, DL, |
| 6370 | PredCond.second); |
| 6371 | return None; |
| 6372 | } |
| 6373 | |
| 6374 | static void setLimitsForBinOp(const BinaryOperator &BO, APInt &Lower, |
| 6375 | APInt &Upper, const InstrInfoQuery &IIQ) { |
| 6376 | unsigned Width = Lower.getBitWidth(); |
| 6377 | const APInt *C; |
| 6378 | switch (BO.getOpcode()) { |
| 6379 | case Instruction::Add: |
| 6380 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) { |
| 6381 | // FIXME: If we have both nuw and nsw, we should reduce the range further. |
| 6382 | if (IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(&BO))) { |
| 6383 | // 'add nuw x, C' produces [C, UINT_MAX]. |
| 6384 | Lower = *C; |
| 6385 | } else if (IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(&BO))) { |
| 6386 | if (C->isNegative()) { |
| 6387 | // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C]. |
| 6388 | Lower = APInt::getSignedMinValue(Width); |
| 6389 | Upper = APInt::getSignedMaxValue(Width) + *C + 1; |
| 6390 | } else { |
| 6391 | // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX]. |
| 6392 | Lower = APInt::getSignedMinValue(Width) + *C; |
| 6393 | Upper = APInt::getSignedMaxValue(Width) + 1; |
| 6394 | } |
| 6395 | } |
| 6396 | } |
| 6397 | break; |
| 6398 | |
| 6399 | case Instruction::And: |
| 6400 | if (match(BO.getOperand(1), m_APInt(C))) |
| 6401 | // 'and x, C' produces [0, C]. |
| 6402 | Upper = *C + 1; |
| 6403 | break; |
| 6404 | |
| 6405 | case Instruction::Or: |
| 6406 | if (match(BO.getOperand(1), m_APInt(C))) |
| 6407 | // 'or x, C' produces [C, UINT_MAX]. |
| 6408 | Lower = *C; |
| 6409 | break; |
| 6410 | |
| 6411 | case Instruction::AShr: |
| 6412 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { |
| 6413 | // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C]. |
| 6414 | Lower = APInt::getSignedMinValue(Width).ashr(*C); |
| 6415 | Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1; |
| 6416 | } else if (match(BO.getOperand(0), m_APInt(C))) { |
| 6417 | unsigned ShiftAmount = Width - 1; |
| 6418 | if (!C->isNullValue() && IIQ.isExact(&BO)) |
| 6419 | ShiftAmount = C->countTrailingZeros(); |
| 6420 | if (C->isNegative()) { |
| 6421 | // 'ashr C, x' produces [C, C >> (Width-1)] |
| 6422 | Lower = *C; |
| 6423 | Upper = C->ashr(ShiftAmount) + 1; |
| 6424 | } else { |
| 6425 | // 'ashr C, x' produces [C >> (Width-1), C] |
| 6426 | Lower = C->ashr(ShiftAmount); |
| 6427 | Upper = *C + 1; |
| 6428 | } |
| 6429 | } |
| 6430 | break; |
| 6431 | |
| 6432 | case Instruction::LShr: |
| 6433 | if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) { |
| 6434 | // 'lshr x, C' produces [0, UINT_MAX >> C]. |
| 6435 | Upper = APInt::getAllOnesValue(Width).lshr(*C) + 1; |
| 6436 | } else if (match(BO.getOperand(0), m_APInt(C))) { |
| 6437 | // 'lshr C, x' produces [C >> (Width-1), C]. |
| 6438 | unsigned ShiftAmount = Width - 1; |
| 6439 | if (!C->isNullValue() && IIQ.isExact(&BO)) |
| 6440 | ShiftAmount = C->countTrailingZeros(); |
| 6441 | Lower = C->lshr(ShiftAmount); |
| 6442 | Upper = *C + 1; |
| 6443 | } |
| 6444 | break; |
| 6445 | |
| 6446 | case Instruction::Shl: |
| 6447 | if (match(BO.getOperand(0), m_APInt(C))) { |
| 6448 | if (IIQ.hasNoUnsignedWrap(&BO)) { |
| 6449 | // 'shl nuw C, x' produces [C, C << CLZ(C)] |
| 6450 | Lower = *C; |
| 6451 | Upper = Lower.shl(Lower.countLeadingZeros()) + 1; |
| 6452 | } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw? |
| 6453 | if (C->isNegative()) { |
| 6454 | // 'shl nsw C, x' produces [C << CLO(C)-1, C] |
| 6455 | unsigned ShiftAmount = C->countLeadingOnes() - 1; |
| 6456 | Lower = C->shl(ShiftAmount); |
| 6457 | Upper = *C + 1; |
| 6458 | } else { |
| 6459 | // 'shl nsw C, x' produces [C, C << CLZ(C)-1] |
| 6460 | unsigned ShiftAmount = C->countLeadingZeros() - 1; |
| 6461 | Lower = *C; |
| 6462 | Upper = C->shl(ShiftAmount) + 1; |
| 6463 | } |
| 6464 | } |
| 6465 | } |
| 6466 | break; |
| 6467 | |
| 6468 | case Instruction::SDiv: |
| 6469 | if (match(BO.getOperand(1), m_APInt(C))) { |
| 6470 | APInt IntMin = APInt::getSignedMinValue(Width); |
| 6471 | APInt IntMax = APInt::getSignedMaxValue(Width); |
| 6472 | if (C->isAllOnesValue()) { |
| 6473 | // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX] |
| 6474 | // where C != -1 and C != 0 and C != 1 |
| 6475 | Lower = IntMin + 1; |
| 6476 | Upper = IntMax + 1; |
| 6477 | } else if (C->countLeadingZeros() < Width - 1) { |
| 6478 | // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C] |
| 6479 | // where C != -1 and C != 0 and C != 1 |
| 6480 | Lower = IntMin.sdiv(*C); |
| 6481 | Upper = IntMax.sdiv(*C); |
| 6482 | if (Lower.sgt(Upper)) |
| 6483 | std::swap(Lower, Upper); |
| 6484 | Upper = Upper + 1; |
| 6485 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6485, __PRETTY_FUNCTION__)); |
| 6486 | } |
| 6487 | } else if (match(BO.getOperand(0), m_APInt(C))) { |
| 6488 | if (C->isMinSignedValue()) { |
| 6489 | // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2]. |
| 6490 | Lower = *C; |
| 6491 | Upper = Lower.lshr(1) + 1; |
| 6492 | } else { |
| 6493 | // 'sdiv C, x' produces [-|C|, |C|]. |
| 6494 | Upper = C->abs() + 1; |
| 6495 | Lower = (-Upper) + 1; |
| 6496 | } |
| 6497 | } |
| 6498 | break; |
| 6499 | |
| 6500 | case Instruction::UDiv: |
| 6501 | if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) { |
| 6502 | // 'udiv x, C' produces [0, UINT_MAX / C]. |
| 6503 | Upper = APInt::getMaxValue(Width).udiv(*C) + 1; |
| 6504 | } else if (match(BO.getOperand(0), m_APInt(C))) { |
| 6505 | // 'udiv C, x' produces [0, C]. |
| 6506 | Upper = *C + 1; |
| 6507 | } |
| 6508 | break; |
| 6509 | |
| 6510 | case Instruction::SRem: |
| 6511 | if (match(BO.getOperand(1), m_APInt(C))) { |
| 6512 | // 'srem x, C' produces (-|C|, |C|). |
| 6513 | Upper = C->abs(); |
| 6514 | Lower = (-Upper) + 1; |
| 6515 | } |
| 6516 | break; |
| 6517 | |
| 6518 | case Instruction::URem: |
| 6519 | if (match(BO.getOperand(1), m_APInt(C))) |
| 6520 | // 'urem x, C' produces [0, C). |
| 6521 | Upper = *C; |
| 6522 | break; |
| 6523 | |
| 6524 | default: |
| 6525 | break; |
| 6526 | } |
| 6527 | } |
| 6528 | |
| 6529 | static void setLimitsForIntrinsic(const IntrinsicInst &II, APInt &Lower, |
| 6530 | APInt &Upper) { |
| 6531 | unsigned Width = Lower.getBitWidth(); |
| 6532 | const APInt *C; |
| 6533 | switch (II.getIntrinsicID()) { |
| 6534 | case Intrinsic::ctpop: |
| 6535 | case Intrinsic::ctlz: |
| 6536 | case Intrinsic::cttz: |
| 6537 | // Maximum of set/clear bits is the bit width. |
| 6538 | assert(Lower == 0 && "Expected lower bound to be zero")((Lower == 0 && "Expected lower bound to be zero") ? static_cast <void> (0) : __assert_fail ("Lower == 0 && \"Expected lower bound to be zero\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6538, __PRETTY_FUNCTION__)); |
| 6539 | Upper = Width + 1; |
| 6540 | break; |
| 6541 | case Intrinsic::uadd_sat: |
| 6542 | // uadd.sat(x, C) produces [C, UINT_MAX]. |
| 6543 | if (match(II.getOperand(0), m_APInt(C)) || |
| 6544 | match(II.getOperand(1), m_APInt(C))) |
| 6545 | Lower = *C; |
| 6546 | break; |
| 6547 | case Intrinsic::sadd_sat: |
| 6548 | if (match(II.getOperand(0), m_APInt(C)) || |
| 6549 | match(II.getOperand(1), m_APInt(C))) { |
| 6550 | if (C->isNegative()) { |
| 6551 | // sadd.sat(x, -C) produces [SINT_MIN, SINT_MAX + (-C)]. |
| 6552 | Lower = APInt::getSignedMinValue(Width); |
| 6553 | Upper = APInt::getSignedMaxValue(Width) + *C + 1; |
| 6554 | } else { |
| 6555 | // sadd.sat(x, +C) produces [SINT_MIN + C, SINT_MAX]. |
| 6556 | Lower = APInt::getSignedMinValue(Width) + *C; |
| 6557 | Upper = APInt::getSignedMaxValue(Width) + 1; |
| 6558 | } |
| 6559 | } |
| 6560 | break; |
| 6561 | case Intrinsic::usub_sat: |
| 6562 | // usub.sat(C, x) produces [0, C]. |
| 6563 | if (match(II.getOperand(0), m_APInt(C))) |
| 6564 | Upper = *C + 1; |
| 6565 | // usub.sat(x, C) produces [0, UINT_MAX - C]. |
| 6566 | else if (match(II.getOperand(1), m_APInt(C))) |
| 6567 | Upper = APInt::getMaxValue(Width) - *C + 1; |
| 6568 | break; |
| 6569 | case Intrinsic::ssub_sat: |
| 6570 | if (match(II.getOperand(0), m_APInt(C))) { |
| 6571 | if (C->isNegative()) { |
| 6572 | // ssub.sat(-C, x) produces [SINT_MIN, -SINT_MIN + (-C)]. |
| 6573 | Lower = APInt::getSignedMinValue(Width); |
| 6574 | Upper = *C - APInt::getSignedMinValue(Width) + 1; |
| 6575 | } else { |
| 6576 | // ssub.sat(+C, x) produces [-SINT_MAX + C, SINT_MAX]. |
| 6577 | Lower = *C - APInt::getSignedMaxValue(Width); |
| 6578 | Upper = APInt::getSignedMaxValue(Width) + 1; |
| 6579 | } |
| 6580 | } else if (match(II.getOperand(1), m_APInt(C))) { |
| 6581 | if (C->isNegative()) { |
| 6582 | // ssub.sat(x, -C) produces [SINT_MIN - (-C), SINT_MAX]: |
| 6583 | Lower = APInt::getSignedMinValue(Width) - *C; |
| 6584 | Upper = APInt::getSignedMaxValue(Width) + 1; |
| 6585 | } else { |
| 6586 | // ssub.sat(x, +C) produces [SINT_MIN, SINT_MAX - C]. |
| 6587 | Lower = APInt::getSignedMinValue(Width); |
| 6588 | Upper = APInt::getSignedMaxValue(Width) - *C + 1; |
| 6589 | } |
| 6590 | } |
| 6591 | break; |
| 6592 | case Intrinsic::umin: |
| 6593 | case Intrinsic::umax: |
| 6594 | case Intrinsic::smin: |
| 6595 | case Intrinsic::smax: |
| 6596 | if (!match(II.getOperand(0), m_APInt(C)) && |
| 6597 | !match(II.getOperand(1), m_APInt(C))) |
| 6598 | break; |
| 6599 | |
| 6600 | switch (II.getIntrinsicID()) { |
| 6601 | case Intrinsic::umin: |
| 6602 | Upper = *C + 1; |
| 6603 | break; |
| 6604 | case Intrinsic::umax: |
| 6605 | Lower = *C; |
| 6606 | break; |
| 6607 | case Intrinsic::smin: |
| 6608 | Lower = APInt::getSignedMinValue(Width); |
| 6609 | Upper = *C + 1; |
| 6610 | break; |
| 6611 | case Intrinsic::smax: |
| 6612 | Lower = *C; |
| 6613 | Upper = APInt::getSignedMaxValue(Width) + 1; |
| 6614 | break; |
| 6615 | default: |
| 6616 | llvm_unreachable("Must be min/max intrinsic")::llvm::llvm_unreachable_internal("Must be min/max intrinsic" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6616); |
| 6617 | } |
| 6618 | break; |
| 6619 | case Intrinsic::abs: |
| 6620 | // If abs of SIGNED_MIN is poison, then the result is [0..SIGNED_MAX], |
| 6621 | // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN. |
| 6622 | if (match(II.getOperand(1), m_One())) |
| 6623 | Upper = APInt::getSignedMaxValue(Width) + 1; |
| 6624 | else |
| 6625 | Upper = APInt::getSignedMinValue(Width) + 1; |
| 6626 | break; |
| 6627 | default: |
| 6628 | break; |
| 6629 | } |
| 6630 | } |
| 6631 | |
| 6632 | static void setLimitsForSelectPattern(const SelectInst &SI, APInt &Lower, |
| 6633 | APInt &Upper, const InstrInfoQuery &IIQ) { |
| 6634 | const Value *LHS = nullptr, *RHS = nullptr; |
| 6635 | SelectPatternResult R = matchSelectPattern(&SI, LHS, RHS); |
| 6636 | if (R.Flavor == SPF_UNKNOWN) |
| 6637 | return; |
| 6638 | |
| 6639 | unsigned BitWidth = SI.getType()->getScalarSizeInBits(); |
| 6640 | |
| 6641 | if (R.Flavor == SelectPatternFlavor::SPF_ABS) { |
| 6642 | // If the negation part of the abs (in RHS) has the NSW flag, |
| 6643 | // then the result of abs(X) is [0..SIGNED_MAX], |
| 6644 | // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN. |
| 6645 | Lower = APInt::getNullValue(BitWidth); |
| 6646 | if (match(RHS, m_Neg(m_Specific(LHS))) && |
| 6647 | IIQ.hasNoSignedWrap(cast<Instruction>(RHS))) |
| 6648 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; |
| 6649 | else |
| 6650 | Upper = APInt::getSignedMinValue(BitWidth) + 1; |
| 6651 | return; |
| 6652 | } |
| 6653 | |
| 6654 | if (R.Flavor == SelectPatternFlavor::SPF_NABS) { |
| 6655 | // The result of -abs(X) is <= 0. |
| 6656 | Lower = APInt::getSignedMinValue(BitWidth); |
| 6657 | Upper = APInt(BitWidth, 1); |
| 6658 | return; |
| 6659 | } |
| 6660 | |
| 6661 | const APInt *C; |
| 6662 | if (!match(LHS, m_APInt(C)) && !match(RHS, m_APInt(C))) |
| 6663 | return; |
| 6664 | |
| 6665 | switch (R.Flavor) { |
| 6666 | case SPF_UMIN: |
| 6667 | Upper = *C + 1; |
| 6668 | break; |
| 6669 | case SPF_UMAX: |
| 6670 | Lower = *C; |
| 6671 | break; |
| 6672 | case SPF_SMIN: |
| 6673 | Lower = APInt::getSignedMinValue(BitWidth); |
| 6674 | Upper = *C + 1; |
| 6675 | break; |
| 6676 | case SPF_SMAX: |
| 6677 | Lower = *C; |
| 6678 | Upper = APInt::getSignedMaxValue(BitWidth) + 1; |
| 6679 | break; |
| 6680 | default: |
| 6681 | break; |
| 6682 | } |
| 6683 | } |
| 6684 | |
| 6685 | ConstantRange llvm::computeConstantRange(const Value *V, bool UseInstrInfo, |
| 6686 | AssumptionCache *AC, |
| 6687 | const Instruction *CtxI, |
| 6688 | unsigned Depth) { |
| 6689 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6689, __PRETTY_FUNCTION__)); |
| 6690 | |
| 6691 | if (Depth == MaxAnalysisRecursionDepth) |
| 6692 | return ConstantRange::getFull(V->getType()->getScalarSizeInBits()); |
| 6693 | |
| 6694 | const APInt *C; |
| 6695 | if (match(V, m_APInt(C))) |
| 6696 | return ConstantRange(*C); |
| 6697 | |
| 6698 | InstrInfoQuery IIQ(UseInstrInfo); |
| 6699 | unsigned BitWidth = V->getType()->getScalarSizeInBits(); |
| 6700 | APInt Lower = APInt(BitWidth, 0); |
| 6701 | APInt Upper = APInt(BitWidth, 0); |
| 6702 | if (auto *BO = dyn_cast<BinaryOperator>(V)) |
| 6703 | setLimitsForBinOp(*BO, Lower, Upper, IIQ); |
| 6704 | else if (auto *II = dyn_cast<IntrinsicInst>(V)) |
| 6705 | setLimitsForIntrinsic(*II, Lower, Upper); |
| 6706 | else if (auto *SI = dyn_cast<SelectInst>(V)) |
| 6707 | setLimitsForSelectPattern(*SI, Lower, Upper, IIQ); |
| 6708 | |
| 6709 | ConstantRange CR = ConstantRange::getNonEmpty(Lower, Upper); |
| 6710 | |
| 6711 | if (auto *I = dyn_cast<Instruction>(V)) |
| 6712 | if (auto *Range = IIQ.getMetadata(I, LLVMContext::MD_range)) |
| 6713 | CR = CR.intersectWith(getConstantRangeFromMetadata(*Range)); |
| 6714 | |
| 6715 | if (CtxI && AC) { |
| 6716 | // Try to restrict the range based on information from assumptions. |
| 6717 | for (auto &AssumeVH : AC->assumptionsFor(V)) { |
| 6718 | if (!AssumeVH) |
| 6719 | continue; |
| 6720 | CallInst *I = cast<CallInst>(AssumeVH); |
| 6721 | assert(I->getParent()->getParent() == CtxI->getParent()->getParent() &&((I->getParent()->getParent() == CtxI->getParent()-> getParent() && "Got assumption for the wrong function!" ) ? static_cast<void> (0) : __assert_fail ("I->getParent()->getParent() == CtxI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6722, __PRETTY_FUNCTION__)) |
| 6722 | "Got assumption for the wrong function!")((I->getParent()->getParent() == CtxI->getParent()-> getParent() && "Got assumption for the wrong function!" ) ? static_cast<void> (0) : __assert_fail ("I->getParent()->getParent() == CtxI->getParent()->getParent() && \"Got assumption for the wrong function!\"" , "/build/llvm-toolchain-snapshot-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6722, __PRETTY_FUNCTION__)); |
| 6723 | 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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6724, __PRETTY_FUNCTION__)) |
| 6724 | "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-13~++20210223111116+16ede0956cb1/llvm/lib/Analysis/ValueTracking.cpp" , 6724, __PRETTY_FUNCTION__)); |
| 6725 | |
| 6726 | if (!isValidAssumeForContext(I, CtxI, nullptr)) |
| 6727 | continue; |
| 6728 | Value *Arg = I->getArgOperand(0); |
| 6729 | ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg); |
| 6730 | // Currently we just use information from comparisons. |
| 6731 | if (!Cmp || Cmp->getOperand(0) != V) |
| 6732 | continue; |
| 6733 | ConstantRange RHS = computeConstantRange(Cmp->getOperand(1), UseInstrInfo, |
| 6734 | AC, I, Depth + 1); |
| 6735 | CR = CR.intersectWith( |
| 6736 | ConstantRange::makeSatisfyingICmpRegion(Cmp->getPredicate(), RHS)); |
| 6737 | } |
| 6738 | } |
| 6739 | |
| 6740 | return CR; |
| 6741 | } |
| 6742 | |
| 6743 | static Optional<int64_t> |
| 6744 | getOffsetFromIndex(const GEPOperator *GEP, unsigned Idx, const DataLayout &DL) { |
| 6745 | // Skip over the first indices. |
| 6746 | gep_type_iterator GTI = gep_type_begin(GEP); |
| 6747 | for (unsigned i = 1; i != Idx; ++i, ++GTI) |
| 6748 | /*skip along*/; |
| 6749 | |
| 6750 | // Compute the offset implied by the rest of the indices. |
| 6751 | int64_t Offset = 0; |
| 6752 | for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { |
| 6753 | ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i)); |
| 6754 | if (!OpC) |
| 6755 | return None; |
| 6756 | if (OpC->isZero()) |
| 6757 | continue; // No offset. |
| 6758 | |
| 6759 | // Handle struct indices, which add their field offset to the pointer. |
| 6760 | if (StructType *STy = GTI.getStructTypeOrNull()) { |
| 6761 | Offset += DL.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); |
| 6762 | continue; |
| 6763 | } |
| 6764 | |
| 6765 | // Otherwise, we have a sequential type like an array or fixed-length |
| 6766 | // vector. Multiply the index by the ElementSize. |
| 6767 | TypeSize Size = DL.getTypeAllocSize(GTI.getIndexedType()); |
| 6768 | if (Size.isScalable()) |
| 6769 | return None; |
| 6770 | Offset += Size.getFixedSize() * OpC->getSExtValue(); |
| 6771 | } |
| 6772 | |
| 6773 | return Offset; |
| 6774 | } |
| 6775 | |
| 6776 | Optional<int64_t> llvm::isPointerOffset(const Value *Ptr1, const Value *Ptr2, |
| 6777 | const DataLayout &DL) { |
| 6778 | Ptr1 = Ptr1->stripPointerCasts(); |
| 6779 | Ptr2 = Ptr2->stripPointerCasts(); |
| 6780 | |
| 6781 | // Handle the trivial case first. |
| 6782 | if (Ptr1 == Ptr2) { |
| 6783 | return 0; |
| 6784 | } |
| 6785 | |
| 6786 | const GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1); |
| 6787 | const GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2); |
| 6788 | |
| 6789 | // If one pointer is a GEP see if the GEP is a constant offset from the base, |
| 6790 | // as in "P" and "gep P, 1". |
| 6791 | // Also do this iteratively to handle the the following case: |
| 6792 | // Ptr_t1 = GEP Ptr1, c1 |
| 6793 | // Ptr_t2 = GEP Ptr_t1, c2 |
| 6794 | // Ptr2 = GEP Ptr_t2, c3 |
| 6795 | // where we will return c1+c2+c3. |
| 6796 | // TODO: Handle the case when both Ptr1 and Ptr2 are GEPs of some common base |
| 6797 | // -- replace getOffsetFromBase with getOffsetAndBase, check that the bases |
| 6798 | // are the same, and return the difference between offsets. |
| 6799 | auto getOffsetFromBase = [&DL](const GEPOperator *GEP, |
| 6800 | const Value *Ptr) -> Optional<int64_t> { |
| 6801 | const GEPOperator *GEP_T = GEP; |
| 6802 | int64_t OffsetVal = 0; |
| 6803 | bool HasSameBase = false; |
| 6804 | while (GEP_T) { |
| 6805 | auto Offset = getOffsetFromIndex(GEP_T, 1, DL); |
| 6806 | if (!Offset) |
| 6807 | return None; |
| 6808 | OffsetVal += *Offset; |
| 6809 | auto Op0 = GEP_T->getOperand(0)->stripPointerCasts(); |
| 6810 | if (Op0 == Ptr) { |
| 6811 | HasSameBase = true; |
| 6812 | break; |
| 6813 | } |
| 6814 | GEP_T = dyn_cast<GEPOperator>(Op0); |
| 6815 | } |
| 6816 | if (!HasSameBase) |
| 6817 | return None; |
| 6818 | return OffsetVal; |
| 6819 | }; |
| 6820 | |
| 6821 | if (GEP1) { |
| 6822 | auto Offset = getOffsetFromBase(GEP1, Ptr2); |
| 6823 | if (Offset) |
| 6824 | return -*Offset; |
| 6825 | } |
| 6826 | if (GEP2) { |
| 6827 | auto Offset = getOffsetFromBase(GEP2, Ptr1); |
| 6828 | if (Offset) |
| 6829 | return Offset; |
| 6830 | } |
| 6831 | |
| 6832 | // Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical |
| 6833 | // base. After that base, they may have some number of common (and |
| 6834 | // potentially variable) indices. After that they handle some constant |
| 6835 | // offset, which determines their offset from each other. At this point, we |
| 6836 | // handle no other case. |
| 6837 | if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0)) |
| 6838 | return None; |
| 6839 | |
| 6840 | // Skip any common indices and track the GEP types. |
| 6841 | unsigned Idx = 1; |
| 6842 | for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx) |
| 6843 | if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx)) |
| 6844 | break; |
| 6845 | |
| 6846 | auto Offset1 = getOffsetFromIndex(GEP1, Idx, DL); |
| 6847 | auto Offset2 = getOffsetFromIndex(GEP2, Idx, DL); |
| 6848 | if (!Offset1 || !Offset2) |
| 6849 | return None; |
| 6850 | return *Offset2 - *Offset1; |
| 6851 | } |