[llvm] [GISel] matchFPSelect to use FMINMAX IEEE variant (PR #123774)

[via llvm-commits]

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@@ -6442,27 +6442,27 @@ unsigned CombinerHelper::getFPMinMaxOpcForSelect(
   case CmpInst::FCMP_OGT:
   case CmpInst::FCMP_OGE:
     if (VsNaNRetVal == SelectPatternNaNBehaviour::RETURNS_OTHER)
-      return TargetOpcode::G_FMAXNUM;
+      return TargetOpcode::G_FMAXNUM_IEEE;
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lialan wrote:

I checked how SDISel works on this, it seems the difference is that in GISel we are being more conservative because of -0 vs 0. 

Now that we are fixing G_FMAXNUM/G_FMINNUM to be similar to IEEE variants, I guess we can just relax the restriction on -0. 

https://github.com/llvm/llvm-project/pull/123774