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Make the "KnownZero ^ TypeMask" computation just once.

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llvm-svn: 35276
This commit is contained in:
Zhou Sheng 2007-03-23 03:13:21 +00:00
parent 6b7b4945f1
commit e706d8f56d
1 changed files with 4 additions and 3 deletions
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7
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -7136,9 +7136,10 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
if (pred != ICmpInst::ICMP_NE && pred != ICmpInst::ICMP_EQ)
break;
if ((KnownZero^TypeMask).isPowerOf2()) { // Exactly 1 possible 1?
APInt KnownZeroMask(KnownZero ^ TypeMask);
if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
bool isNE = pred == ICmpInst::ICMP_NE;
if (Op1CV != 0 && (Op1CV != (KnownZero^TypeMask))) {
if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
// (X&4) == 2 --> false
// (X&4) != 2 --> true
Constant *Res = ConstantInt::get(Type::Int1Ty, isNE);
@ -7146,7 +7147,7 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
return ReplaceInstUsesWith(CI, Res);
}
unsigned ShiftAmt = (KnownZero^TypeMask).logBase2();
unsigned ShiftAmt = KnownZeroMask.logBase2();
Value *In = Op0;
if (ShiftAmt) {
// Perform a logical shr by shiftamt.