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-rw-r--r--lib/Analysis/ConstantFolding.cpp160
1 files changed, 105 insertions, 55 deletions
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 782acfa..0ac1cb5 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -56,7 +56,7 @@ static Constant *FoldBitCast(Constant *C, Type *DestTy,
// Handle a vector->integer cast.
if (IntegerType *IT = dyn_cast<IntegerType>(DestTy)) {
VectorType *VTy = dyn_cast<VectorType>(C->getType());
- if (VTy == 0)
+ if (!VTy)
return ConstantExpr::getBitCast(C, DestTy);
unsigned NumSrcElts = VTy->getNumElements();
@@ -73,7 +73,7 @@ static Constant *FoldBitCast(Constant *C, Type *DestTy,
}
ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(C);
- if (CDV == 0)
+ if (!CDV)
return ConstantExpr::getBitCast(C, DestTy);
// Now that we know that the input value is a vector of integers, just shift
@@ -93,7 +93,7 @@ static Constant *FoldBitCast(Constant *C, Type *DestTy,
// The code below only handles casts to vectors currently.
VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
- if (DestVTy == 0)
+ if (!DestVTy)
return ConstantExpr::getBitCast(C, DestTy);
// If this is a scalar -> vector cast, convert the input into a <1 x scalar>
@@ -411,32 +411,32 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
TD.getTypeAllocSizeInBits(LoadTy),
AS);
} else
- return 0;
+ return nullptr;
C = FoldBitCast(C, MapTy, TD);
if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, TD))
return FoldBitCast(Res, LoadTy, TD);
- return 0;
+ return nullptr;
}
unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8;
if (BytesLoaded > 32 || BytesLoaded == 0)
- return 0;
+ return nullptr;
GlobalValue *GVal;
APInt Offset;
if (!IsConstantOffsetFromGlobal(C, GVal, Offset, TD))
- return 0;
+ return nullptr;
GlobalVariable *GV = dyn_cast<GlobalVariable>(GVal);
if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
!GV->getInitializer()->getType()->isSized())
- return 0;
+ return nullptr;
// If we're loading off the beginning of the global, some bytes may be valid,
// but we don't try to handle this.
if (Offset.isNegative())
- return 0;
+ return nullptr;
// If we're not accessing anything in this constant, the result is undefined.
if (Offset.getZExtValue() >=
@@ -446,7 +446,7 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
unsigned char RawBytes[32] = {0};
if (!ReadDataFromGlobal(GV->getInitializer(), Offset.getZExtValue(), RawBytes,
BytesLoaded, TD))
- return 0;
+ return nullptr;
APInt ResultVal = APInt(IntType->getBitWidth(), 0);
if (TD.isLittleEndian()) {
@@ -466,6 +466,52 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
return ConstantInt::get(IntType->getContext(), ResultVal);
}
+static Constant *ConstantFoldLoadThroughBitcast(ConstantExpr *CE,
+ const DataLayout *DL) {
+ if (!DL)
+ return nullptr;
+ auto *DestPtrTy = dyn_cast<PointerType>(CE->getType());
+ if (!DestPtrTy)
+ return nullptr;
+ Type *DestTy = DestPtrTy->getElementType();
+
+ Constant *C = ConstantFoldLoadFromConstPtr(CE->getOperand(0), DL);
+ if (!C)
+ return nullptr;
+
+ do {
+ Type *SrcTy = C->getType();
+
+ // If the type sizes are the same and a cast is legal, just directly
+ // cast the constant.
+ if (DL->getTypeSizeInBits(DestTy) == DL->getTypeSizeInBits(SrcTy)) {
+ Instruction::CastOps Cast = Instruction::BitCast;
+ // If we are going from a pointer to int or vice versa, we spell the cast
+ // differently.
+ if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
+ Cast = Instruction::IntToPtr;
+ else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
+ Cast = Instruction::PtrToInt;
+
+ if (CastInst::castIsValid(Cast, C, DestTy))
+ return ConstantExpr::getCast(Cast, C, DestTy);
+ }
+
+ // If this isn't an aggregate type, there is nothing we can do to drill down
+ // and find a bitcastable constant.
+ if (!SrcTy->isAggregateType())
+ return nullptr;
+
+ // We're simulating a load through a pointer that was bitcast to point to
+ // a different type, so we can try to walk down through the initial
+ // elements of an aggregate to see if some part of th e aggregate is
+ // castable to implement the "load" semantic model.
+ C = C->getAggregateElement(0u);
+ } while (C);
+
+ return nullptr;
+}
+
/// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
/// produce if it is constant and determinable. If this is not determinable,
/// return null.
@@ -479,7 +525,7 @@ Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
// If the loaded value isn't a constant expr, we can't handle it.
ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
if (!CE)
- return 0;
+ return nullptr;
if (CE->getOpcode() == Instruction::GetElementPtr) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
@@ -491,6 +537,10 @@ Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
}
}
+ if (CE->getOpcode() == Instruction::BitCast)
+ if (Constant *LoadedC = ConstantFoldLoadThroughBitcast(CE, TD))
+ return LoadedC;
+
// Instead of loading constant c string, use corresponding integer value
// directly if string length is small enough.
StringRef Str;
@@ -542,16 +592,16 @@ Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C,
// Try hard to fold loads from bitcasted strange and non-type-safe things.
if (TD)
return FoldReinterpretLoadFromConstPtr(CE, *TD);
- return 0;
+ return nullptr;
}
static Constant *ConstantFoldLoadInst(const LoadInst *LI, const DataLayout *TD){
- if (LI->isVolatile()) return 0;
+ if (LI->isVolatile()) return nullptr;
if (Constant *C = dyn_cast<Constant>(LI->getOperand(0)))
return ConstantFoldLoadFromConstPtr(C, TD);
- return 0;
+ return nullptr;
}
/// SymbolicallyEvaluateBinop - One of Op0/Op1 is a constant expression.
@@ -571,8 +621,8 @@ static Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0,
unsigned BitWidth = DL->getTypeSizeInBits(Op0->getType()->getScalarType());
APInt KnownZero0(BitWidth, 0), KnownOne0(BitWidth, 0);
APInt KnownZero1(BitWidth, 0), KnownOne1(BitWidth, 0);
- ComputeMaskedBits(Op0, KnownZero0, KnownOne0, DL);
- ComputeMaskedBits(Op1, KnownZero1, KnownOne1, DL);
+ computeKnownBits(Op0, KnownZero0, KnownOne0, DL);
+ computeKnownBits(Op1, KnownZero1, KnownOne1, DL);
if ((KnownOne1 | KnownZero0).isAllOnesValue()) {
// All the bits of Op0 that the 'and' could be masking are already zero.
return Op0;
@@ -608,7 +658,7 @@ static Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0,
}
}
- return 0;
+ return nullptr;
}
/// CastGEPIndices - If array indices are not pointer-sized integers,
@@ -618,7 +668,7 @@ static Constant *CastGEPIndices(ArrayRef<Constant *> Ops,
Type *ResultTy, const DataLayout *TD,
const TargetLibraryInfo *TLI) {
if (!TD)
- return 0;
+ return nullptr;
Type *IntPtrTy = TD->getIntPtrType(ResultTy);
@@ -641,7 +691,7 @@ static Constant *CastGEPIndices(ArrayRef<Constant *> Ops,
}
if (!Any)
- return 0;
+ return nullptr;
Constant *C = ConstantExpr::getGetElementPtr(Ops[0], NewIdxs);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
@@ -676,7 +726,7 @@ static Constant *SymbolicallyEvaluateGEP(ArrayRef<Constant *> Ops,
Constant *Ptr = Ops[0];
if (!TD || !Ptr->getType()->getPointerElementType()->isSized() ||
!Ptr->getType()->isPointerTy())
- return 0;
+ return nullptr;
Type *IntPtrTy = TD->getIntPtrType(Ptr->getType());
Type *ResultElementTy = ResultTy->getPointerElementType();
@@ -690,7 +740,7 @@ static Constant *SymbolicallyEvaluateGEP(ArrayRef<Constant *> Ops,
// "inttoptr (sub (ptrtoint Ptr), V)"
if (Ops.size() == 2 && ResultElementTy->isIntegerTy(8)) {
ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[1]);
- assert((CE == 0 || CE->getType() == IntPtrTy) &&
+ assert((!CE || CE->getType() == IntPtrTy) &&
"CastGEPIndices didn't canonicalize index types!");
if (CE && CE->getOpcode() == Instruction::Sub &&
CE->getOperand(0)->isNullValue()) {
@@ -702,7 +752,7 @@ static Constant *SymbolicallyEvaluateGEP(ArrayRef<Constant *> Ops,
return Res;
}
}
- return 0;
+ return nullptr;
}
unsigned BitWidth = TD->getTypeSizeInBits(IntPtrTy);
@@ -765,7 +815,7 @@ static Constant *SymbolicallyEvaluateGEP(ArrayRef<Constant *> Ops,
// Only handle pointers to sized types, not pointers to functions.
if (!ATy->getElementType()->isSized())
- return 0;
+ return nullptr;
}
// Determine which element of the array the offset points into.
@@ -810,7 +860,7 @@ static Constant *SymbolicallyEvaluateGEP(ArrayRef<Constant *> Ops,
// type, then the offset is pointing into the middle of an indivisible
// member, so we can't simplify it.
if (Offset != 0)
- return 0;
+ return nullptr;
// Create a GEP.
Constant *C = ConstantExpr::getGetElementPtr(Ptr, NewIdxs);
@@ -841,7 +891,7 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I,
const TargetLibraryInfo *TLI) {
// Handle PHI nodes quickly here...
if (PHINode *PN = dyn_cast<PHINode>(I)) {
- Constant *CommonValue = 0;
+ Constant *CommonValue = nullptr;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming = PN->getIncomingValue(i);
@@ -854,14 +904,14 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I,
// If the incoming value is not a constant, then give up.
Constant *C = dyn_cast<Constant>(Incoming);
if (!C)
- return 0;
+ return nullptr;
// Fold the PHI's operands.
if (ConstantExpr *NewC = dyn_cast<ConstantExpr>(C))
C = ConstantFoldConstantExpression(NewC, TD, TLI);
// If the incoming value is a different constant to
// the one we saw previously, then give up.
if (CommonValue && C != CommonValue)
- return 0;
+ return nullptr;
CommonValue = C;
}
@@ -876,7 +926,7 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I,
for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) {
Constant *Op = dyn_cast<Constant>(*i);
if (!Op)
- return 0; // All operands not constant!
+ return nullptr; // All operands not constant!
// Fold the Instruction's operands.
if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(Op))
@@ -966,14 +1016,14 @@ Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, Type *DestTy,
}
switch (Opcode) {
- default: return 0;
+ default: return nullptr;
case Instruction::ICmp:
case Instruction::FCmp: llvm_unreachable("Invalid for compares");
case Instruction::Call:
if (Function *F = dyn_cast<Function>(Ops.back()))
if (canConstantFoldCallTo(F))
return ConstantFoldCall(F, Ops.slice(0, Ops.size() - 1), TLI);
- return 0;
+ return nullptr;
case Instruction::PtrToInt:
// If the input is a inttoptr, eliminate the pair. This requires knowing
// the width of a pointer, so it can't be done in ConstantExpr::getCast.
@@ -1142,14 +1192,14 @@ Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
ConstantExpr *CE) {
if (!CE->getOperand(1)->isNullValue())
- return 0; // Do not allow stepping over the value!
+ return nullptr; // Do not allow stepping over the value!
// Loop over all of the operands, tracking down which value we are
// addressing.
for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i) {
C = C->getAggregateElement(CE->getOperand(i));
- if (C == 0)
- return 0;
+ if (!C)
+ return nullptr;
}
return C;
}
@@ -1164,8 +1214,8 @@ Constant *llvm::ConstantFoldLoadThroughGEPIndices(Constant *C,
// addressing.
for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
C = C->getAggregateElement(Indices[i]);
- if (C == 0)
- return 0;
+ if (!C)
+ return nullptr;
}
return C;
}
@@ -1270,7 +1320,7 @@ static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
V = NativeFP(V);
if (sys::llvm_fenv_testexcept()) {
sys::llvm_fenv_clearexcept();
- return 0;
+ return nullptr;
}
return GetConstantFoldFPValue(V, Ty);
@@ -1282,7 +1332,7 @@ static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
V = NativeFP(V, W);
if (sys::llvm_fenv_testexcept()) {
sys::llvm_fenv_clearexcept();
- return 0;
+ return nullptr;
}
return GetConstantFoldFPValue(V, Ty);
@@ -1311,7 +1361,7 @@ static Constant *ConstantFoldConvertToInt(const APFloat &Val,
/*isSigned=*/true, mode,
&isExact);
if (status != APFloat::opOK && status != APFloat::opInexact)
- return 0;
+ return nullptr;
return ConstantInt::get(Ty, UIntVal, /*isSigned=*/true);
}
@@ -1345,7 +1395,7 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
}
if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
- return 0;
+ return nullptr;
if (IntrinsicID == Intrinsic::round) {
APFloat V = Op->getValueAPF();
@@ -1357,7 +1407,7 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
/// likely to be aborted with an exception anyway, and some host libms
/// have known errors raising exceptions.
if (Op->getValueAPF().isNaN() || Op->getValueAPF().isInfinity())
- return 0;
+ return nullptr;
/// Currently APFloat versions of these functions do not exist, so we use
/// the host native double versions. Float versions are not called
@@ -1396,7 +1446,7 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
}
if (!TLI)
- return 0;
+ return nullptr;
switch (Name[0]) {
case 'a':
@@ -1467,7 +1517,7 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
default:
break;
}
- return 0;
+ return nullptr;
}
if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
@@ -1491,7 +1541,7 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
return ConstantFP::get(Ty->getContext(), Val);
}
default:
- return 0;
+ return nullptr;
}
}
@@ -1523,21 +1573,21 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
if (isa<UndefValue>(Operands[0])) {
if (IntrinsicID == Intrinsic::bswap)
return Operands[0];
- return 0;
+ return nullptr;
}
- return 0;
+ return nullptr;
}
if (Operands.size() == 2) {
if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
- return 0;
+ return nullptr;
double Op1V = getValueAsDouble(Op1);
if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
if (Op2->getType() != Op1->getType())
- return 0;
+ return nullptr;
double Op2V = getValueAsDouble(Op2);
if (IntrinsicID == Intrinsic::pow) {
@@ -1550,7 +1600,7 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
return ConstantFP::get(Ty->getContext(), V1);
}
if (!TLI)
- return 0;
+ return nullptr;
if (Name == "pow" && TLI->has(LibFunc::pow))
return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
if (Name == "fmod" && TLI->has(LibFunc::fmod))
@@ -1571,7 +1621,7 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
APFloat((double)std::pow((double)Op1V,
(int)Op2C->getZExtValue())));
}
- return 0;
+ return nullptr;
}
if (ConstantInt *Op1 = dyn_cast<ConstantInt>(Operands[0])) {
@@ -1624,13 +1674,13 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
}
}
- return 0;
+ return nullptr;
}
- return 0;
+ return nullptr;
}
if (Operands.size() != 3)
- return 0;
+ return nullptr;
if (const ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
if (const ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
@@ -1646,14 +1696,14 @@ static Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID,
if (s != APFloat::opInvalidOp)
return ConstantFP::get(Ty->getContext(), V);
- return 0;
+ return nullptr;
}
}
}
}
}
- return 0;
+ return nullptr;
}
static Constant *ConstantFoldVectorCall(StringRef Name, unsigned IntrinsicID,
@@ -1690,7 +1740,7 @@ Constant *
llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
const TargetLibraryInfo *TLI) {
if (!F->hasName())
- return 0;
+ return nullptr;
StringRef Name = F->getName();
Type *Ty = F->getReturnType();
generated by cgit v1.1 at 2024-12-22 14:28:06 +0000