[clang] [llvm] [AMDGPU] Error out in clang if wavefront64 is used on gfx1250 (PR #153693)

[Matt Arsenault via cfe-commits]

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@@ -774,6 +774,18 @@ static bool isWave32Capable(StringRef GPU, const Triple &T) {
   return IsWave32Capable;
 }
 
+static bool isWave64Capable(StringRef GPU, const Triple &T) {
+  if (T.isAMDGCN()) {
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arsenm wrote:

This should be added to the feature flags in the big table above, and not require multiple parse + switch functions for different cases 

https://github.com/llvm/llvm-project/pull/153693