diff options
Diffstat (limited to 'llvm/lib/Analysis/InstructionSimplify.cpp')
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index b9e6bdb..1212161 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -21,6 +21,7 @@ #include "llvm/ADT/SetVector.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/CaptureTracking.h" #include "llvm/Analysis/ConstantFolding.h" #include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/Analysis/ValueTracking.h" @@ -1922,10 +1923,10 @@ static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred, // If the C and C++ standards are ever made sufficiently restrictive in this // area, it may be possible to update LLVM's semantics accordingly and reinstate // this optimization. -static Constant *computePointerICmp(const DataLayout &DL, - const TargetLibraryInfo *TLI, - CmpInst::Predicate Pred, Value *LHS, - Value *RHS) { +static Constant * +computePointerICmp(const DataLayout &DL, const TargetLibraryInfo *TLI, + const DominatorTree *DT, CmpInst::Predicate Pred, + const Instruction *CxtI, Value *LHS, Value *RHS) { // First, skip past any trivial no-ops. LHS = LHS->stripPointerCasts(); RHS = RHS->stripPointerCasts(); @@ -2081,6 +2082,21 @@ static Constant *computePointerICmp(const DataLayout &DL, (IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs))) return ConstantInt::get(GetCompareTy(LHS), !CmpInst::isTrueWhenEqual(Pred)); + + // Fold comparisons for non-escaping pointer even if the allocation call + // cannot be elided. We cannot fold malloc comparison to null. Also, the + // dynamic allocation call could be either of the operands. + Value *MI = nullptr; + if (isAllocLikeFn(LHS, TLI) && llvm::isKnownNonNullAt(RHS, CxtI, DT, TLI)) + MI = LHS; + else if (isAllocLikeFn(RHS, TLI) && + llvm::isKnownNonNullAt(LHS, CxtI, DT, TLI)) + MI = RHS; + // FIXME: We should also fold the compare when the pointer escapes, but the + // compare dominates the pointer escape + if (MI && !PointerMayBeCaptured(MI, true, true)) + return ConstantInt::get(GetCompareTy(LHS), + CmpInst::isFalseWhenEqual(Pred)); } // Otherwise, fail. @@ -3027,7 +3043,7 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, // Simplify comparisons of related pointers using a powerful, recursive // GEP-walk when we have target data available.. if (LHS->getType()->isPointerTy()) - if (Constant *C = computePointerICmp(Q.DL, Q.TLI, Pred, LHS, RHS)) + if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.CxtI, LHS, RHS)) return C; if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) { |