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

[Yingwei Zheng via llvm-commits]

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@@ -1180,7 +1180,7 @@ Instruction *InstCombinerImpl::foldIntrinsicIsFPClass(IntrinsicInst &II) {
   // If none of the tests which can return false are possible, fold to true.
   // fp_class (nnan x), ~(qnan|snan) -> true
   // fp_class (ninf x), ~(ninf|pinf) -> true
-  if (Mask == Known.KnownFPClasses)
+  if ((Known.KnownFPClasses & ~Mask) == fcNone)
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dtcxzyw wrote:

Please add a test to demonstrate the issue. See also https://llvm.org/docs/InstCombineContributorGuide.html#precommit-tests.


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