[llvm] [InstCombine] Fold more 'fcmp' 'select' instrs idioms into 'fabs' (PR #83381)

[Joshua Cranmer via llvm-commits]

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@@ -1112,6 +1113,13 @@ void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
         for (unsigned i = 0; i != NumEdges; ++i)
           APN->addIncoming(IncomingVals[AllocaNo], Pred);
 
+        if (APN->isComplete() &&
+            APN->getFunction()->hasFnAttribute("no-signed-zeros-fp-math") &&
+            any_of(APN->incoming_values(),
+                   [](Value *V) { return isa<FPMathOperator>(V); })) {
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jcranmer-intel wrote:

`isa<FPMathOperator>(APN)` would work better instead.

https://github.com/llvm/llvm-project/pull/83381