Map `SV_VertexID` to `gl_VertexIndex-gl_BaseVertex`, add `SV_Vulkan*ID` semantics (#7150)

* Map SV_VertexID to `gl_VertexIndex - gl_BaseVertex`, provide SV_Vulkan* SV semantics

* Fix docs

* Regenerate toc

* Fix affected pointer-2 test

* Add tests

---------

Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 26 insertions, 5 deletions

diff --git a/source/slang/glsl.meta.slang b/source/slang/glsl.meta.slang
index 2d9078855..588396251 100644
--- a/source/slang/glsl.meta.slang
+++ b/source/slang/glsl.meta.slang
@@ -159,6 +159,9 @@ public property uint3 gl_WorkGroupSize
 public in int gl_InvocationID : SV_GSInstanceID;
 
 internal in int __sv_InstanceIndex : SV_InstanceID;
+internal in int __sv_VertexIndex : SV_VertexID;
+internal in int __sv_VulkanInstanceIndex : SV_VulkanInstanceID;
+internal in int __sv_VulkanVertexIndex : SV_VulkanVertexID;
 
 // SPIRV InstanceIndex builtin for vertex shader
 public property int gl_InstanceIndex
@@ -168,24 +171,42 @@ public property int gl_InstanceIndex
     {
         __target_switch
         {
+        case glsl:
+        case spirv:
+        case metal:
+        case wgsl:
+            return __sv_VulkanInstanceIndex;
         default:
             return __sv_InstanceIndex;
+        }
+    }
+}
+
+// SPIRV VertexIndex builtin for vertex shader
+public property int gl_VertexIndex
+{
+    [require(vertex)]
+    get
+    {
+        __target_switch
+        {
         case glsl:
-            __intrinsic_asm "gl_InstanceIndex";
         case spirv:
-            return spirv_asm {
-                result:$$int = OpLoad builtin(InstanceIndex:int);
-            };
+        case metal:
+        case wgsl:
+            return __sv_VulkanVertexIndex;
+        default:
+            return __sv_VertexIndex;
         }
     }
 }
+
 public in bool gl_FrontFacing : SV_IsFrontFace;
 
 // TODO: define overload for geometry stage.
 public in int gl_Layer : SV_RenderTargetArrayIndex;
 
 public in int gl_SampleID : SV_SampleIndex;
-public in int gl_VertexIndex : SV_VertexID;
 public in int gl_ViewIndex : SV_ViewID;
 public in int gl_ViewportIndex : SV_ViewportArrayIndex;
 public in int gl_BaseVertex : SV_StartVertexLocation;