[llvm] R600: Expand is_fpclass (PR #135234)

[Matt Arsenault via llvm-commits]

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@@ -100,6 +100,11 @@ R600TargetLowering::R600TargetLowering(const TargetMachine &TM,
 
   setOperationAction(ISD::FSUB, MVT::f32, Expand);
 
+  setOperationAction(ISD::IS_FPCLASS,
+                     {MVT::f32, MVT::v2f32, MVT::v3f32, MVT::v4f32, MVT::v5f32,
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arsenm wrote:

It turns out this is also working around some kind of bug in select / select_cc handling so I'm going to leave it alone 

https://github.com/llvm/llvm-project/pull/135234