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Implement sub.ll:test14

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12355 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-03-13 00:11:49 +00:00
parent eb416e85bc
commit bfe492b5c2
1 changed files with 29 additions and 8 deletions
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37
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -549,6 +549,21 @@ static unsigned getTypeSizeInBits(const Type *Ty) {
return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
}
/// RemoveNoopCast - Strip off nonconverting casts from the value.
///
static Value *RemoveNoopCast(Value *V) {
if (CastInst *CI = dyn_cast<CastInst>(V)) {
const Type *CTy = CI->getType();
const Type *OpTy = CI->getOperand(0)->getType();
if (CTy->isInteger() && OpTy->isInteger()) {
if (CTy->getPrimitiveSize() == OpTy->getPrimitiveSize())
return RemoveNoopCast(CI->getOperand(0));
} else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
return RemoveNoopCast(CI->getOperand(0));
}
return V;
}
Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
@ -572,17 +587,18 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
ConstantInt::get(I.getType(), 1)));
// -((uint)X >> 31) -> ((int)X >> 31)
// -((int)X >> 31) -> ((uint)X >> 31)
if (C->isNullValue())
if (ShiftInst *SI = dyn_cast<ShiftInst>(Op1))
if (C->isNullValue()) {
Value *NoopCastedRHS = RemoveNoopCast(Op1);
if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
if (SI->getOpcode() == Instruction::Shr)
if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
const Type *NewTy;
if (C->getType()->isSigned())
NewTy = getUnsignedIntegralType(C->getType());
if (SI->getType()->isSigned())
NewTy = getUnsignedIntegralType(SI->getType());
else
NewTy = getSignedIntegralType(C->getType());
NewTy = getSignedIntegralType(SI->getType());
// Check to see if we are shifting out everything but the sign bit.
if (CU->getValue() == C->getType()->getPrimitiveSize()*8-1) {
if (CU->getValue() == SI->getType()->getPrimitiveSize()*8-1) {
// Ok, the transformation is safe. Insert a cast of the incoming
// value, then the new shift, then the new cast.
Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
@ -590,10 +606,15 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Value *InV = InsertNewInstBefore(FirstCast, I);
Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
CU, SI->getName());
InV = InsertNewInstBefore(NewShift, I);
return new CastInst(NewShift, I.getType());
if (NewShift->getType() == I.getType())
return NewShift;
else {
InV = InsertNewInstBefore(NewShift, I);
return new CastInst(NewShift, I.getType());
}
}
}
}
}
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))