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author | Dan Gohman <gohman@apple.com> | 2009-07-17 22:25:10 +0000 |
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committer | Dan Gohman <gohman@apple.com> | 2009-07-17 22:25:10 +0000 |
commit | 3a7a68c10880c2a28387617b42d14d774e218727 (patch) | |
tree | 19703b7ade7ad668d0c54a0d0f97d2f0bce51d82 | |
parent | 8f080f0233ce28044182e3c81f3ebc12d43e081e (diff) | |
download | external_llvm-3a7a68c10880c2a28387617b42d14d774e218727.zip external_llvm-3a7a68c10880c2a28387617b42d14d774e218727.tar.gz external_llvm-3a7a68c10880c2a28387617b42d14d774e218727.tar.bz2 |
Make BasicAliasAnalysis and Value::getUnderlyingObject use
GEPOperator's hasNoPointer0verflow(), and make a few places in instcombine
that create GEPs that may overflow clear the NoOverflow value. Among
other things, this partially addresses PR2831.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76252 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 10 | ||||
-rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 20 | ||||
-rw-r--r-- | lib/VMCore/Value.cpp | 14 |
3 files changed, 28 insertions, 16 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index c10c6f3..dcb5903 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -23,6 +23,7 @@ #include "llvm/Instructions.h" #include "llvm/IntrinsicInst.h" #include "llvm/LLVMContext.h" +#include "llvm/Operator.h" #include "llvm/Pass.h" #include "llvm/Target/TargetData.h" #include "llvm/ADT/SmallVector.h" @@ -38,10 +39,11 @@ using namespace llvm; //===----------------------------------------------------------------------===// static const User *isGEP(const Value *V) { - if (isa<GetElementPtrInst>(V) || - (isa<ConstantExpr>(V) && - cast<ConstantExpr>(V)->getOpcode() == Instruction::GetElementPtr)) - return cast<User>(V); + if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) + // For the purposes of BasicAliasAnalysis, if the GEP has overflow it + // could do crazy things. + if (GEP->hasNoPointerOverflow()) + return GEP; return 0; } diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 9ddd0e0..dbdf449 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -2310,7 +2310,10 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { cast<PointerType>(CI->getOperand(0)->getType())->getAddressSpace(); Value *I2 = InsertBitCastBefore(CI->getOperand(0), Context->getPointerType(Type::Int8Ty, AS), I); - I2 = InsertNewInstBefore(GetElementPtrInst::Create(I2, Other, "ctg2"), I); + GetElementPtrInst *GEP = GetElementPtrInst::Create(I2, Other, "ctg2"); + // A GEP formed from an arbitrary add may overflow. + cast<GEPOperator>(GEP)->setHasNoPointerOverflow(false); + I2 = InsertNewInstBefore(GEP, I); return new PtrToIntInst(I2, CI->getType()); } } @@ -8942,7 +8945,12 @@ Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) { // If Offset is evenly divisible by Size, we can do this xform. if (Size && !APIntOps::srem(Offset, APInt(Offset.getBitWidth(), Size))){ Offset = APIntOps::sdiv(Offset, APInt(Offset.getBitWidth(), Size)); - return GetElementPtrInst::Create(X, Context->getConstantInt(Offset)); + GetElementPtrInst *GEP = + GetElementPtrInst::Create(X, Context->getConstantInt(Offset)); + // A gep synthesized from inttoptr+add+ptrtoint must be assumed to + // potentially overflow, in the absense of further analysis. + cast<GEPOperator>(GEP)->setHasNoPointerOverflow(false); + return GEP; } } // TODO: Could handle other cases, e.g. where add is indexing into field of @@ -8966,8 +8974,12 @@ Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) { Instruction *P = InsertNewInstBefore(new IntToPtrInst(X, CI.getType(), "tmp"), CI); - return GetElementPtrInst::Create(P, - Context->getConstantInt(Offset), "tmp"); + GetElementPtrInst *GEP = + GetElementPtrInst::Create(P, Context->getConstantInt(Offset), "tmp"); + // A gep synthesized from inttoptr+add+ptrtoint must be assumed to + // potentially overflow, in the absense of further analysis. + cast<GEPOperator>(GEP)->setHasNoPointerOverflow(false); + return GEP; } } return 0; diff --git a/lib/VMCore/Value.cpp b/lib/VMCore/Value.cpp index b35ad50..3322c68 100644 --- a/lib/VMCore/Value.cpp +++ b/lib/VMCore/Value.cpp @@ -16,6 +16,7 @@ #include "llvm/DerivedTypes.h" #include "llvm/InstrTypes.h" #include "llvm/Instructions.h" +#include "llvm/Operator.h" #include "llvm/Module.h" #include "llvm/ValueSymbolTable.h" #include "llvm/Support/Debug.h" @@ -372,15 +373,12 @@ Value *Value::getUnderlyingObject() { Value *V = this; unsigned MaxLookup = 6; do { - if (Instruction *I = dyn_cast<Instruction>(V)) { - if (!isa<BitCastInst>(I) && !isa<GetElementPtrInst>(I)) + if (Operator *O = dyn_cast<Operator>(V)) { + if (O->getOpcode() != Instruction::BitCast && + (O->getOpcode() != Instruction::GetElementPtr || + !cast<GEPOperator>(V)->hasNoPointerOverflow())) return V; - V = I->getOperand(0); - } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { - if (CE->getOpcode() != Instruction::BitCast && - CE->getOpcode() != Instruction::GetElementPtr) - return V; - V = CE->getOperand(0); + V = O->getOperand(0); } else { return V; } |