Address PR comments and update AttrDocs.td

Author: Zhengxing Li

clang/include/clang/Basic/AttrDocs.td

@@ -7819,9 +7819,8 @@ randomized.
 def HLSLSV_GroupIDDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
-The ``SV_GroupID`` semantic, when applied to an input parameter, specifies a
-data binding to map the group id to the specified parameter. This attribute is
-only supported in compute shaders.
+The ``SV_GroupID`` semantic, when applied to an input parameter, specifies which
+thread group a shader is executing in. This attribute is only supported in compute shaders.
 
 The full documentation is available here: https://docs.microsoft.com/en-us/windows/win32/direct3dhlsl/sv-groupid
   }];

clang/test/CodeGenHLSL/semantics/SV_GroupID.hlsl

@@ -19,3 +19,14 @@ void foo(uint Idx : SV_GroupID) {}
 [numthreads(8,8,1)]
 void bar(uint2 Idx : SV_GroupID) {}
 
+// CHECK:  define void @test()
+// CHECK:  %[[#ID_X:]] = call i32 @llvm.dx.group.id(i32 0)
+// CHECK:  %[[#ID_X_:]] = insertelement <3 x i32> poison, i32 %[[#ID_X]], i64 0
+// CHECK:  %[[#ID_Y:]] = call i32 @llvm.dx.group.id(i32 1)
+// CHECK:  %[[#ID_XY:]] = insertelement <3 x i32> %[[#ID_X_]], i32 %[[#ID_Y]], i64 1
+// CHECK:  %[[#ID_Z:]] = call i32 @llvm.dx.group.id(i32 2)
+// CHECK:  %[[#ID_XYZ:]] = insertelement <3 x i32> %[[#ID_XY]], i32 %[[#ID_Z]], i64 2
+// CHECK:  call void @{{.*}}test{{.*}}(<3 x i32> %[[#ID_XYZ]])
+[shader("compute")]
+[numthreads(8,8,1)]
+void test(uint3 Idx : SV_GroupID) {}

clang/test/SemaHLSL/Semantics/invalid_entry_parameter.hlsl

@@ -48,4 +48,4 @@ struct ST2_GID {
 // expected-warning@+1 {{'SV_GroupID' attribute only applies to parameters and non-static data members}}
     static uint GID : SV_GroupID;
     uint s_gid : SV_GroupID;
-};
+};