[llvm] [InstCombine] simplify `x (comp) ~x` (PR #73990)
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Fri Dec 1 01:04:16 PST 2023
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@@ -7035,6 +7035,63 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
return new ICmpInst(I.getSwappedPredicate(Pred), Builder.CreateXor(X, Y),
Z);
+ // Transform X s< ~X --> X s< 0
+ // X s> ~X --> X s> -1
+ // X s>= ~X --> X s> ~X
+ // X s<= ~X --> X s< ~X
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ParkHanbum wrote:
I have a question.
if result of code I added are different with result of PASS, which result is better to comment?
example. in my code, `X u<= ~X` transform to `X u> -128` but PASS final result is `X s> -1`
https://github.com/llvm/llvm-project/pull/73990
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