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Fix two bugs: one where a condition was mistakenly swapped, and another

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where we folded (X & 254) -> X < 1 instead of X < 2.  These problems were
latent problems exposed by the latest patch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16528 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-09-27 19:29:18 +00:00
parent dffb445503
commit 83c4ec0372
1 changed files with 11 additions and 14 deletions
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25
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1522,7 +1522,7 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
unsigned ShiftOp = Shift->getOpcode() == Instruction::Shl
? Instruction::Shr : Instruction::Shl;
Constant *NewCst = ConstantExpr::get(ShiftOp, CI, ShAmt);
// Check to see if we are shifting out any of the bits being
// compared.
if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
@ -1545,7 +1545,8 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
}
}
break;
case Instruction::Shr: // shr: (setcc (shr X, ShAmt), CI)
case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
unsigned ShAmtVal = ShAmt->getValue();
@ -1721,31 +1722,27 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
// If 'X' is not signed, insert a cast now...
if (!BOC->getType()->isSigned()) {
const Type *DestTy = BOC->getType()->getSignedVersion();
CastInst *NewCI = new CastInst(X,DestTy,X->getName()+".signed");
InsertNewInstBefore(NewCI, I);
X = NewCI;
X = InsertCastBefore(X, DestTy, I);
}
return new SetCondInst(isSetNE ? Instruction::SetLT :
Instruction::SetGE, X,
Constant::getNullValue(X->getType()));
}
// ((X & ~7) == 0) --> X < 7
// ((X & ~7) == 0) --> X < 8
if (CI->isNullValue() && isHighOnes(BOC)) {
Value *X = BO->getOperand(0);
Constant *NotX = ConstantExpr::getNot(BOC);
Constant *NegX = ConstantExpr::getNeg(BOC);
// If 'X' is signed, insert a cast now.
if (!NotX->getType()->isSigned()) {
const Type *DestTy = NotX->getType()->getUnsignedVersion();
CastInst *NewCI = new CastInst(X, DestTy, X->getName()+".uns");
InsertNewInstBefore(NewCI, I);
X = NewCI;
NotX = ConstantExpr::getCast(NotX, DestTy);
if (NegX->getType()->isSigned()) {
const Type *DestTy = NegX->getType()->getUnsignedVersion();
X = InsertCastBefore(X, DestTy, I);
NegX = ConstantExpr::getCast(NegX, DestTy);
}
return new SetCondInst(isSetNE ? Instruction::SetGE :
Instruction::SetLT, X, NotX);
Instruction::SetLT, X, NegX);
}
}