[llvm] [AMDGPU] Remove default wavefrontsize attribute in asm parser (PR #97617)

[Matt Arsenault via llvm-commits]

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@@ -1408,7 +1408,20 @@ class AMDGPUAsmParser : public MCTargetAsmParser {
       copySTI().ToggleFeature("southern-islands");
     }
 
-    setAvailableFeatures(ComputeAvailableFeatures(getFeatureBits()));
+    StringRef FS = getSTI().getFeatureString();
+    FeatureBitset FB = getFeatureBits();
+    int isWave32 = FS.contains("+wavefrontsize32");
+    int isWave64 = FS.contains("+wavefrontsize64");
+    // Reset default wavefrontsize features.
+    if (isWave32 + isWave64 == 1) {
+      if (isWave32 && FB[AMDGPU::FeatureWavefrontSize64])
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arsenm wrote:

We shouldn't really be directly checking the bits. The + and -s are sequentially evaluated in the subtarget construction to set the WavefrontSize field. I would expect the same to happen down in MC. I don't know why the subtarget evaluation logic isn't an an MCSubtarget superclass 

https://github.com/llvm/llvm-project/pull/97617