[llvm] [ConstraintElim] Check the other signedness when hasSameSign (PR #128168)

[Ramkumar Ramachandra via llvm-commits]

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@@ -1460,6 +1460,13 @@ static bool checkAndReplaceCondition(
           checkCondition(Cmp->getPredicate(), Cmp->getOperand(0),
                          Cmp->getOperand(1), Cmp, Info))
     return ReplaceCmpWithConstant(Cmp, *ImpliedCondition);
+
+  if (Cmp->hasSameSign())
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artagnon wrote:

You could use `Cmp->getCmpPredicate()`, tweak `Cmp->hasSameSign()` to `Pred->hasSameSign()`, and also check `ICmpInst::isRelational(Pred)` here?

https://github.com/llvm/llvm-project/pull/128168