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* Rearrange code slightly

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* Disable broken transforms for simplifying (setcc (cast X to larger), CI)
  where CC is not != or ==

llvm-svn: 17422
This commit is contained in:
Chris Lattner 2004-11-02 03:50:32 +00:00
parent 34bc328438
commit 33ed2c8984
1 changed files with 20 additions and 11 deletions
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31
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -2024,29 +2024,38 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
if (SrcTy == Type::BoolTy) SrcBits = 1;
unsigned DestBits = LHSI->getType()->getPrimitiveSize()*8;
if (LHSI->getType() == Type::BoolTy) DestBits = 1;
if (SrcBits < DestBits) {
if (SrcBits < DestBits &&
// FIXME: Reenable the code below for < and >. However, we have
// to handle the cases when the source of the cast and the dest of
// the cast have different signs. e.g:
// (cast sbyte %X to uint) >u 255U -> X <s (sbyte)0
(I.getOpcode() == Instruction::SetEQ ||
I.getOpcode() == Instruction::SetNE)) {
// Check to see if the comparison is always true or false.
Constant *NewCst = ConstantExpr::getCast(CI, SrcTy);
if (ConstantExpr::getCast(NewCst, LHSI->getType()) != CI) {
Constant *Min = ConstantIntegral::getMinValue(SrcTy);
Constant *Max = ConstantIntegral::getMaxValue(SrcTy);
Min = ConstantExpr::getCast(Min, LHSI->getType());
Max = ConstantExpr::getCast(Max, LHSI->getType());
switch (I.getOpcode()) {
default: assert(0 && "unknown integer comparison");
#if 0
case Instruction::SetLT: {
Constant *Max = ConstantIntegral::getMaxValue(SrcTy);
Max = ConstantExpr::getCast(Max, LHSI->getType());
return ReplaceInstUsesWith(I, ConstantExpr::getSetLT(Max, CI));
}
case Instruction::SetGT: {
Constant *Min = ConstantIntegral::getMinValue(SrcTy);
Min = ConstantExpr::getCast(Min, LHSI->getType());
return ReplaceInstUsesWith(I, ConstantExpr::getSetGT(Min, CI));
}
#endif
case Instruction::SetEQ:
return ReplaceInstUsesWith(I, ConstantBool::False);
case Instruction::SetNE:
return ReplaceInstUsesWith(I, ConstantBool::True);
case Instruction::SetLT:
return ReplaceInstUsesWith(I, ConstantExpr::getSetLT(Max, CI));
case Instruction::SetGT:
return ReplaceInstUsesWith(I, ConstantExpr::getSetGT(Min, CI));
}
}
return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
ConstantExpr::getCast(CI, SrcTy));
return new SetCondInst(I.getOpcode(), LHSI->getOperand(0), NewCst);
}
}
break;