On Fri, 2006-12-22 at 13:31 -0800, Chris Lattner wrote:
>
> + // We're performing a signed comparison.
> + if (isSignedExt) {
> + // Signed extend and signed comparison.
> + if (cast<ConstantInt>(CI)->getSExtValue() < 0)// X < (small)
> --> false
> + Result = ConstantBool::getFalse();
> + else
> + Result = ConstantBool::getTrue(); // X < (large)
> --> true
> + } else {
> + // Zero extend and signed comparison.
> + if (cast<ConstantInt>(CI)->getSExtValue() < 0)
> + Result = ConstantBool::getFalse();
> + else
> + Result = ConstantBool::getTrue();
> }
>
>
> My reading of this code says that you can eliminate the 'if
> issignedext' test, as the if/then cases are the same. Is this a bug
> or just code duplication?
I'm not Sure. The original (before any signless types changes, rev
1.525) looks like this:
if (DestTy->isSigned()) {
// We're performing a signed comparison.
if (isSignSrc) {
// Signed extend and signed comparison.
if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) -->
false
Result = ConstantBool::getFalse();
else
Result = ConstantBool::getTrue(); // X < (large) -->
true
} else {
// Unsigned extend and signed comparison.
if (cast<ConstantSInt>(CI)->getValue() < 0)
Result = ConstantBool::getFalse();
else
Result = ConstantBool::getTrue();
}
Clearly getting the ZExt value and comparing with < 0 is just silly
(unsigned is never less than zero). I'm inclined to think this is
either a long-standing bug or just some code duplication. I'll
eliminate the redundancy because it is clearly generating the same
results in either case. However, I'm not convinced this isn't a bug.
Reid.
>
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