[clang] [llvm] [Transforms][Utils][PromoteMem2Reg] Propagate nnan flag on par with the nsz flag (PR #114271)

[Nikita Popov via cfe-commits]

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@@ -1140,6 +1148,15 @@ void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
         if (isa<FPMathOperator>(APN) && NoSignedZeros)
           APN->setHasNoSignedZeros(true);
 
+        // This allows select instruction folding relevant to floating point
+        // reductions whose operand is a PHI.
+        if (isa<FPMathOperator>(APN) && NoNaNs)
+          APN->setHasNoNaNs(true);
+
+        // Handle NoInfs flag too.
+        if (isa<FPMathOperator>(APN) && NoInfs)
+          APN->setHasNoInfs(true);
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nikic wrote:

I'd suggest to extract a common `if (isa<FPMathOperator>(APN))` around all three.

https://github.com/llvm/llvm-project/pull/114271