[clang] [HLSL] Implement SV_GroupThreadId semantic (PR #117781)

[Tex Riddell via cfe-commits]

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@@ -2,15 +2,18 @@
 // RUN: %clang_cc1 -triple dxil-pc-shadermodel6.0-mesh -hlsl-entry CSMain -x hlsl -finclude-default-header  -verify -o - %s
 
 [numthreads(8,8,1)]
-// expected-error at +3 {{attribute 'SV_GroupIndex' is unsupported in 'mesh' shaders, requires compute}}
-// expected-error at +2 {{attribute 'SV_DispatchThreadID' is unsupported in 'mesh' shaders, requires compute}}
-// expected-error at +1 {{attribute 'SV_GroupID' is unsupported in 'mesh' shaders, requires compute}}
-void CSMain(int GI : SV_GroupIndex, uint ID : SV_DispatchThreadID, uint GID : SV_GroupID) {
-// CHECK: FunctionDecl 0x{{[0-9a-fA-F]+}} <{{.*}}> line:[[@LINE-1]]:6 CSMain 'void (int, uint, uint)'
+// expected-error at +4 {{attribute 'SV_GroupIndex' is unsupported in 'mesh' shaders, requires compute}}
+// expected-error at +3 {{attribute 'SV_DispatchThreadID' is unsupported in 'mesh' shaders, requires compute}}
+// expected-error at +2 {{attribute 'SV_GroupID' is unsupported in 'mesh' shaders, requires compute}}
+// expected-error at +1 {{attribute 'SV_GroupThreadID' is unsupported in 'mesh' shaders, requires compute}}
+void CSMain(int GI : SV_GroupIndex, uint ID : SV_DispatchThreadID, uint GID : SV_GroupID, uint GThreadID : SV_GroupThreadID) {
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tex3d wrote:

Why is this using mesh shader as the example of a stage where these are illegal?  These are actually legal for the mesh shader stage.

https://github.com/llvm/llvm-project/pull/117781