[llvm] [X86] Fix optmasks handling for AVX10.1-256 (PR #73074)

[Evgenii Kudriashov via llvm-commits]

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@@ -939,7 +939,8 @@ std::vector<MCInst> ExegesisX86Target::setRegTo(const MCSubtargetInfo &STI,
       }
       break;
     case 64:
-      if (STI.getFeatureBits()[X86::FeatureBWI]) {
+      if (STI.getFeatureBits()[X86::FeatureBWI] &&
+          STI.getFeatureBits()[X86::FeatureEVEX512]) {
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e-kud wrote:

Unfortunately there is no implementation in case of `FeatureBWI && !FeatureEVEX512`, so it falls into `return {}; // Not yet implemented`. I haven't found any tests checking such case. So, decided not to add a test.

https://github.com/llvm/llvm-project/pull/73074