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Implement cast.ll::test14/15

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11742 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-02-23 07:16:20 +00:00
parent 3c4de7fbe0
commit c5943fb186
1 changed files with 37 additions and 0 deletions
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37
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1378,6 +1378,43 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
default: break;
}
}
} else { // Not a SetEQ/SetNE
// If the LHS is a cast from an integral value of the same size,
if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
Value *CastOp = Cast->getOperand(0);
const Type *SrcTy = CastOp->getType();
unsigned SrcTySize = SrcTy->getPrimitiveSize();
if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
SrcTySize == Cast->getType()->getPrimitiveSize()) {
assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
"Source and destination signednesses should differ!");
if (Cast->getType()->isSigned()) {
// If this is a signed comparison, check for comparisons in the
// vicinity of zero.
if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
// X < 0 => x > 127
return BinaryOperator::create(Instruction::SetGT, CastOp,
ConstantUInt::get(SrcTy, (1ULL << (SrcTySize*8-1))-1));
else if (I.getOpcode() == Instruction::SetGT &&
cast<ConstantSInt>(CI)->getValue() == -1)
// X > -1 => x < 128
return BinaryOperator::create(Instruction::SetGT, CastOp,
ConstantUInt::get(SrcTy, 1ULL << (SrcTySize*8-1)));
} else {
ConstantUInt *CUI = cast<ConstantUInt>(CI);
if (I.getOpcode() == Instruction::SetLT &&
CUI->getValue() == 1ULL << (SrcTySize*8-1))
// X < 128 => X > -1
return BinaryOperator::create(Instruction::SetGT, CastOp,
ConstantSInt::get(SrcTy, -1));
else if (I.getOpcode() == Instruction::SetGT &&
CUI->getValue() == (1ULL << (SrcTySize*8-1))-1)
// X > 127 => X < 0
return BinaryOperator::create(Instruction::SetLT, CastOp,
Constant::getNullValue(SrcTy));
}
}
}
}
// Check to see if we are comparing against the minimum or maximum value...