diff options
Diffstat (limited to 'contrib/llvm/lib/IR/ConstantFold.cpp')
| -rw-r--r-- | contrib/llvm/lib/IR/ConstantFold.cpp | 125 |
1 files changed, 88 insertions, 37 deletions
diff --git a/contrib/llvm/lib/IR/ConstantFold.cpp b/contrib/llvm/lib/IR/ConstantFold.cpp index 395ac39..9176bf2 100644 --- a/contrib/llvm/lib/IR/ConstantFold.cpp +++ b/contrib/llvm/lib/IR/ConstantFold.cpp @@ -27,12 +27,14 @@ #include "llvm/IR/GlobalVariable.h" #include "llvm/IR/Instructions.h" #include "llvm/IR/Operator.h" +#include "llvm/IR/PatternMatch.h" #include "llvm/Support/Compiler.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/ManagedStatic.h" #include "llvm/Support/MathExtras.h" #include <limits> using namespace llvm; +using namespace llvm::PatternMatch; //===----------------------------------------------------------------------===// // ConstantFold*Instruction Implementations @@ -593,8 +595,13 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, bool ignored; uint64_t x[2]; uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); - (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, - APFloat::rmTowardZero, &ignored); + if (APFloat::opInvalidOp == + V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI, + APFloat::rmTowardZero, &ignored)) { + // Undefined behavior invoked - the destination type can't represent + // the input constant. + return UndefValue::get(DestTy); + } APInt Val(DestBitWidth, x); return ConstantInt::get(FPC->getContext(), Val); } @@ -653,9 +660,13 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, APInt api = CI->getValue(); APFloat apf(DestTy->getFltSemantics(), APInt::getNullValue(DestTy->getPrimitiveSizeInBits())); - (void)apf.convertFromAPInt(api, - opc==Instruction::SIToFP, - APFloat::rmNearestTiesToEven); + if (APFloat::opOverflow & + apf.convertFromAPInt(api, opc==Instruction::SIToFP, + APFloat::rmNearestTiesToEven)) { + // Undefined behavior invoked - the destination type can't represent + // the input constant. + return UndefValue::get(DestTy); + } return ConstantFP::get(V->getContext(), apf); } return nullptr; @@ -674,6 +685,9 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V, } return nullptr; case Instruction::Trunc: { + if (V->getType()->isVectorTy()) + return nullptr; + uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth(); if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { return ConstantInt::get(V->getContext(), @@ -901,49 +915,70 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, return C1; return Constant::getNullValue(C1->getType()); // undef & X -> 0 case Instruction::Mul: { - ConstantInt *CI; - // X * undef -> undef if X is odd or undef - if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) || - ((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) || - (isa<UndefValue>(C1) && isa<UndefValue>(C2))) - return UndefValue::get(C1->getType()); + // undef * undef -> undef + if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) + return C1; + const APInt *CV; + // X * undef -> undef if X is odd + if (match(C1, m_APInt(CV)) || match(C2, m_APInt(CV))) + if ((*CV)[0]) + return UndefValue::get(C1->getType()); // X * undef -> 0 otherwise return Constant::getNullValue(C1->getType()); } - case Instruction::UDiv: case Instruction::SDiv: + case Instruction::UDiv: + // X / undef -> undef + if (match(C1, m_Zero())) + return C2; + // undef / 0 -> undef // undef / 1 -> undef - if (Opcode == Instruction::UDiv || Opcode == Instruction::SDiv) - if (ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) - if (CI2->isOne()) - return C1; - // FALL THROUGH + if (match(C2, m_Zero()) || match(C2, m_One())) + return C1; + // undef / X -> 0 otherwise + return Constant::getNullValue(C1->getType()); case Instruction::URem: case Instruction::SRem: - if (!isa<UndefValue>(C2)) // undef / X -> 0 - return Constant::getNullValue(C1->getType()); - return C2; // X / undef -> undef + // X % undef -> undef + if (match(C2, m_Undef())) + return C2; + // undef % 0 -> undef + if (match(C2, m_Zero())) + return C1; + // undef % X -> 0 otherwise + return Constant::getNullValue(C1->getType()); case Instruction::Or: // X | undef -> -1 if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // undef | undef -> undef return C1; return Constant::getAllOnesValue(C1->getType()); // undef | X -> ~0 case Instruction::LShr: - if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) - return C1; // undef lshr undef -> undef - return Constant::getNullValue(C1->getType()); // X lshr undef -> 0 - // undef lshr X -> 0 + // X >>l undef -> undef + if (isa<UndefValue>(C2)) + return C2; + // undef >>l 0 -> undef + if (match(C2, m_Zero())) + return C1; + // undef >>l X -> 0 + return Constant::getNullValue(C1->getType()); case Instruction::AShr: - if (!isa<UndefValue>(C2)) // undef ashr X --> all ones - return Constant::getAllOnesValue(C1->getType()); - else if (isa<UndefValue>(C1)) - return C1; // undef ashr undef -> undef - else - return C1; // X ashr undef --> X + // X >>a undef -> undef + if (isa<UndefValue>(C2)) + return C2; + // undef >>a 0 -> undef + if (match(C2, m_Zero())) + return C1; + // TODO: undef >>a X -> undef if the shift is exact + // undef >>a X -> 0 + return Constant::getNullValue(C1->getType()); case Instruction::Shl: - if (isa<UndefValue>(C2) && isa<UndefValue>(C1)) - return C1; // undef shl undef -> undef - // undef << X -> 0 or X << undef -> 0 + // X << undef -> undef + if (isa<UndefValue>(C2)) + return C2; + // undef << 0 -> undef + if (match(C2, m_Zero())) + return C1; + // undef << X -> 0 return Constant::getNullValue(C1->getType()); } } @@ -1336,9 +1371,24 @@ static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) { static ICmpInst::Predicate areGlobalsPotentiallyEqual(const GlobalValue *GV1, const GlobalValue *GV2) { + auto isGlobalUnsafeForEquality = [](const GlobalValue *GV) { + if (GV->hasExternalWeakLinkage() || GV->hasWeakAnyLinkage()) + return true; + if (const auto *GVar = dyn_cast<GlobalVariable>(GV)) { + Type *Ty = GVar->getType()->getPointerElementType(); + // A global with opaque type might end up being zero sized. + if (!Ty->isSized()) + return true; + // A global with an empty type might lie at the address of any other + // global. + if (Ty->isEmptyTy()) + return true; + } + return false; + }; // Don't try to decide equality of aliases. if (!isa<GlobalAlias>(GV1) && !isa<GlobalAlias>(GV2)) - if (!GV1->hasExternalWeakLinkage() || !GV2->hasExternalWeakLinkage()) + if (!isGlobalUnsafeForEquality(GV1) && !isGlobalUnsafeForEquality(GV2)) return ICmpInst::ICMP_NE; return ICmpInst::BAD_ICMP_PREDICATE; } @@ -2144,9 +2194,10 @@ static Constant *ConstantFoldGetElementPtrImpl(Constant *C, // If all indices are known integers and normalized, we can do a simple // check for the "inbounds" property. - if (!Unknown && !inBounds && - isa<GlobalVariable>(C) && isInBoundsIndices(Idxs)) - return ConstantExpr::getInBoundsGetElementPtr(C, Idxs); + if (!Unknown && !inBounds) + if (auto *GV = dyn_cast<GlobalVariable>(C)) + if (!GV->hasExternalWeakLinkage() && isInBoundsIndices(Idxs)) + return ConstantExpr::getInBoundsGetElementPtr(C, Idxs); return nullptr; } |
