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Oops, X+0.0 isn't foldable, but X+-0.0 is. 

llvm-svn: 23772
This commit is contained in:
Chris Lattner 2005-10-17 17:56:38 +00:00
parent 32979336a7
commit 7fde91e365
1 changed files with 5 additions and 4 deletions
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9
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -694,11 +694,12 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
return ReplaceInstUsesWith(I, RHS); return ReplaceInstUsesWith(I, RHS);
// X + 0 --> X // X + 0 --> X
// NOTE: -0 + +0 = +0 in non-default rounding modes. When we support them if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0.
// we must disable this. Note that 0.0-0.0 = -0.0, so this doesn't hold if (RHSC->isNullValue())
// for SUB. return ReplaceInstUsesWith(I, LHS);
if (RHSC->isNullValue()) } else if (cast<ConstantFP>(RHSC)->isExactlyValue(-0.0)) {
return ReplaceInstUsesWith(I, LHS); return ReplaceInstUsesWith(I, LHS);
}
// X + (signbit) --> X ^ signbit // X + (signbit) --> X ^ signbit
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) { if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {