add convergent attribute

Author: Keenuts

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -1471,11 +1471,13 @@ double4 trunc(double4);
 /// true, across all active lanes in the current wave.
 _HLSL_AVAILABILITY(shadermodel, 6.0)
 _HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_active_count_bits)
+__attribute__((convergent))
 uint WaveActiveCountBits(bool Val);
 
 /// \brief Returns the index of the current lane within the current wave.
 _HLSL_AVAILABILITY(shadermodel, 6.0)
 _HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_get_lane_index)
+__attribute__((convergent))
 uint WaveGetLaneIndex();
 
 } // namespace hlsl