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Make sure the use of ConstantInt::getZExtValue() for shift amount safe.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35510 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Zhou Sheng 2007-03-30 17:20:39 +00:00
parent 4ac93f9fa3
commit 302748dd30
1 changed files with 20 additions and 18 deletions
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38
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1354,7 +1354,7 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
}
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
unsigned ShiftAmt = SA->getZExtValue();
uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
// Signed shift right.
APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
@ -2095,12 +2095,12 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
// -(X >>u 31) -> (X >>s 31)
// -(X >>s 31) -> (X >>u 31)
if (C->isNullValue()) {
if (C->isZero()) {
if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1))
if (SI->getOpcode() == Instruction::LShr) {
if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
// Check to see if we are shifting out everything but the sign bit.
if (CU->getZExtValue() ==
if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
SI->getType()->getPrimitiveSizeInBits()-1) {
// Ok, the transformation is safe. Insert AShr.
return BinaryOperator::create(Instruction::AShr,
@ -2111,7 +2111,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
else if (SI->getOpcode() == Instruction::AShr) {
if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
// Check to see if we are shifting out everything but the sign bit.
if (CU->getZExtValue() ==
if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
SI->getType()->getPrimitiveSizeInBits()-1) {
// Ok, the transformation is safe. Insert LShr.
return BinaryOperator::createLShr(
@ -4789,7 +4789,8 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
if (!CanFold) {
// To test for the bad case of the signed shr, see if any
// of the bits shifted in could be tested after the mask.
int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getZExtValue();
uint32_t TyBits = Ty->getPrimitiveSizeInBits();
int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
@ -4883,7 +4884,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
if (LHSI->hasOneUse()) {
// Otherwise strength reduce the shift into an and.
unsigned ShAmtVal = (unsigned)ShAmt->getZExtValue();
uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
Constant *Mask = ConstantInt::get(CI->getType(), Val);
@ -4926,7 +4927,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
}
if (LHSI->hasOneUse() || CI->isNullValue()) {
unsigned ShAmtVal = (unsigned)ShAmt->getZExtValue();
uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
// Otherwise strength reduce the shift into an and.
APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
@ -5658,7 +5659,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
Op0BO->getOperand(1)->getName());
InsertNewInstBefore(X, I); // (X + (Y << C))
uint32_t Op1Val = Op1->getZExtValue();
uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
return BinaryOperator::createAnd(X, ConstantInt::get(
APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
}
@ -5697,7 +5698,7 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
BinaryOperator::create(Op0BO->getOpcode(), V1, YS,
Op0BO->getOperand(0)->getName());
InsertNewInstBefore(X, I); // (X + (Y << C))
uint32_t Op1Val = Op1->getZExtValue();
uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
return BinaryOperator::createAnd(X, ConstantInt::get(
APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
}
@ -6084,8 +6085,9 @@ static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
// If we are truncating the result of this SHL, and if it's a shift of a
// constant amount, we can always perform a SHL in a smaller type.
if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
if (Ty->getBitWidth() < OrigTy->getBitWidth() &&
CI->getZExtValue() < Ty->getBitWidth())
uint32_t BitWidth = Ty->getBitWidth();
if (BitWidth < OrigTy->getBitWidth() &&
CI->getLimitedValue(BitWidth) < BitWidth)
return CanEvaluateInDifferentType(I->getOperand(0), Ty,NumCastsRemoved);
}
break;
@ -6095,12 +6097,12 @@ static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
// lshr iff we know that the bits we would otherwise be shifting in are
// already zeros.
if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
uint32_t BitWidth = OrigTy->getBitWidth();
if (Ty->getBitWidth() < BitWidth &&
uint32_t OrigBitWidth = OrigTy->getBitWidth();
uint32_t BitWidth = Ty->getBitWidth();
if (BitWidth < OrigBitWidth &&
MaskedValueIsZero(I->getOperand(0),
APInt::getAllOnesValue(BitWidth) &
APInt::getAllOnesValue(Ty->getBitWidth()).zextOrTrunc(BitWidth).flip())
&& CI->getZExtValue() < Ty->getBitWidth()) {
APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
CI->getLimitedValue(BitWidth) < BitWidth) {
return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved);
}
}
@ -6396,7 +6398,7 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
// simplifications.
if (DestBitSize < SrcBitSize &&
isa<ConstantInt>(Op1)) {
unsigned ShiftAmt = cast<ConstantInt>(Op1)->getZExtValue();
uint32_t ShiftAmt = cast<ConstantInt>(Op1)->getLimitedValue(SrcBitSize);
if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
// Insert the new logical shift right.
return BinaryOperator::createLShr(Op0, Op1);
@ -6486,7 +6488,7 @@ Instruction *InstCombiner::visitTrunc(CastInst &CI) {
// We can shrink lshr to something smaller if we know the bits shifted in
// are already zeros.
if (ConstantInt *ShAmtV = dyn_cast<ConstantInt>(SrcI->getOperand(1))) {
unsigned ShAmt = ShAmtV->getZExtValue();
uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
// Get a mask for the bits shifting in.
APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));