[clang] [llvm] [llvm][AMDGPU] Fold `llvm.amdgcn.wavefrontsize` early (PR #114481)

[Alex Voicu via cfe-commits]

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@@ -1024,6 +1024,15 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
     }
     break;
   }
+  case Intrinsic::amdgcn_wavefrontsize: {
+    // TODO: this is a workaround for the pseudo-generic target one gets with no
+    // specified mcpu, which spoofs its wave size to 64; it should be removed.
+    if ((ST->getCPU().empty() || ST->getCPU() == "generic") &&
+        !ST->getFeatureString().contains("+wavefrontsize"))
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AlexVlx wrote:

Since this is a temporary hack, what's the point of putting it in the subtarget so that people get ideas, start using it, and then there's even more technical debt? The parsing might have to change anyway once we have a proper generic target (which the current hack is not).

https://github.com/llvm/llvm-project/pull/114481