[llvm] [llvm][InstCombine] Fold signum(x) into scmp(x, 0) (PR #143445)

[Nikita Popov via llvm-commits]

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@@ -3603,6 +3603,18 @@ Instruction *InstCombinerImpl::foldSelectToCmp(SelectInst &SI) {
        ICmpInst::getSwappedPredicate(ExtendedCmpPredicate) == Pred))
     Replace = true;
 
+  // Handle the edge case (x > -1) ? zext(x != 0), -1
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nikic wrote:

This can also occur with other constants, not just -1 / 0: https://alive2.llvm.org/ce/z/TIceGg

https://github.com/llvm/llvm-project/pull/143445