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1. Make the APInt variable do the binary operation stuff if possible 

instead of using ConstantExpr::getXX.
2. Use constant reference to APInt if possible instead of expensive
   APInt copy.

llvm-svn: 35443
This commit is contained in:
Zhou Sheng 2007-03-29 01:57:21 +00:00
parent cc560c93eb
commit 4961cf1c06
1 changed files with 5 additions and 3 deletions
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8
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -540,8 +540,10 @@ static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
if (I->getOpcode() == Instruction::Shl)
if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
// The multiplier is really 1 << CST.
Constant *One = ConstantInt::get(V->getType(), 1);
CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
uint32_t CSTVal = CST->getValue().getActiveBits() > 64 ?
BitWidth : CST->getZExtValue();
CST = ConstantInt::get(APInt(BitWidth, 1).shl(CSTVal));
return I->getOperand(0);
}
}
@ -2264,7 +2266,7 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
if (CI->isAllOnesValue()) // X * -1 == 0 - X
return BinaryOperator::createNeg(Op0, I.getName());
APInt Val(cast<ConstantInt>(CI)->getValue());
const APInt& Val = cast<ConstantInt>(CI)->getValue();
if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
return BinaryOperator::createShl(Op0,
ConstantInt::get(Op0->getType(), Val.logBase2()));