[llvm] [InstCombine] Resolve incorrect submasking in foldIntrinsicIsFPClass (PR #190504)

[Matt Arsenault via llvm-commits]

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@@ -863,6 +863,37 @@ define i1 @test_class_is_not_nan_nnan_src_strict(float %x) strictfp {
   ret i1 %class
 }
 
+; Fold to true when known classes are a strict subset of the mask
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arsenm wrote:

Would changing this result in one less reprocessing of the instruction? 

https://github.com/llvm/llvm-project/pull/190504