[clang] [llvm] [HLSL] Add WaveGetLaneCount() intrinsic to FE (PR #143127)

[Nathan Gauër via llvm-commits]

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@@ -4909,6 +4909,12 @@ def HLSLWaveReadLaneAt : LangBuiltin<"HLSL_LANG"> {
   let Prototype = "void(...)";
 }
 
+def HLSLWaveGetLaneCount : LangBuiltin<"HLSL_LANG"> {
+  let Spellings = ["__builtin_hlsl_wave_get_lane_count"];
+  let Attributes = [NoThrow, Const];
+  let Prototype = "unsigned int()";
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Keenuts wrote:

Not sure I understand, this is for `WaveGetLaneCount()` which returns the number of lanes. Or am I misunderstanding the comment?

https://github.com/llvm/llvm-project/pull/143127