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Fix missed optimization opportunity when analyzing cast of mul and select.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53151 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky
2008-07-05 21:19:34 +00:00
parent 364d73ddab
commit b8cd6a49b5
2 changed files with 43 additions and 9 deletions
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23
lib/Transforms/Scalar/InstructionCombining.cpp
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@@ -6917,6 +6917,7 @@ bool InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
switch (I->getOpcode()) {
case Instruction::Add:
case Instruction::Sub:
case Instruction::Mul:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
@@ -6926,14 +6927,6 @@ bool InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
NumCastsRemoved);
case Instruction::Mul:
// A multiply can be truncated by truncating its operands.
return Ty->getBitWidth() < OrigTy->getBitWidth() &&
CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
NumCastsRemoved) &&
CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
NumCastsRemoved);
case Instruction::Shl:
// 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.
@@ -6970,7 +6963,13 @@ bool InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
if (I->getOpcode() == CastOpc)
return true;
break;
case Instruction::Select: {
SelectInst *SI = cast<SelectInst>(I);
return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
NumCastsRemoved) &&
CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
NumCastsRemoved);
}
case Instruction::PHI: {
// We can change a phi if we can change all operands.
PHINode *PN = cast<PHINode>(I);
@@ -7028,6 +7027,12 @@ Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
Ty);
break;
case Instruction::Select: {
Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
Res = SelectInst::Create(I->getOperand(0), True, False);
break;
}
case Instruction::PHI: {
PHINode *OPN = cast<PHINode>(I);
PHINode *NPN = PHINode::Create(Ty);