Add WorkgroupCount function (#7734)

Fixes #7733

Copy gl_NumWorkGroups into hlsl.meta.slang as WorkgroupCount function so
that it can be used for GLSL and SPIR-V targets without GLSL syntax.

Also change WorkgroupSize function to allow use with mesh shading capability.
Update pipeline/rasterization/mesh/task-simple.slang to test it in task and mesh stages.

2 files changed, 20 insertions, 10 deletions

diff --git a/source/slang/glsl.meta.slang b/source/slang/glsl.meta.slang
index b3323a327..dfa858eca 100644
--- a/source/slang/glsl.meta.slang
+++ b/source/slang/glsl.meta.slang
@@ -141,25 +141,18 @@ public property int gl_DeviceIndex
 public property uint3 gl_NumWorkGroups
 {
     [require(glsl_spirv, GLSL_430_SPIRV_1_0_compute)]
+    [require(glsl_spirv, meshshading)]
     get 
     {
-        __target_switch
-        {
-        case glsl:
-            __intrinsic_asm "(gl_NumWorkGroups)";
-        case spirv:
-            return spirv_asm {
-                    result:$$uint3 = OpLoad builtin(NumWorkgroups:uint3);
-                };
-        }
+        return WorkgroupCount();
     }
 }
 
-[require(compute)]
 public property uint3 gl_WorkGroupSize
 {
     [__unsafeForceInlineEarly]
     [require(compute)]
+    [require(meshshading)]
     get
     {
         return WorkgroupSize();
diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang
index c1449f3cb..f7efc3a51 100644
--- a/source/slang/hlsl.meta.slang
+++ b/source/slang/hlsl.meta.slang
@@ -6619,9 +6619,26 @@ void AllMemoryBarrierWithGroupSync()
 
 // Returns the workgroup size of the calling entry point.
 [require(compute)]
+[require(meshshading)]
 __intrinsic_op($(kIROp_GetWorkGroupSize))
 int3 WorkgroupSize();
 
+// Returns number of workgroups that have been dispatched to a GLSL or SPIR-V compute shader
+[require(glsl_spirv, GLSL_430_SPIRV_1_0_compute)]
+[require(glsl_spirv, meshshading)]
+uint3 WorkgroupCount()
+{
+    __target_switch
+    {
+    case glsl:
+        __intrinsic_asm "(gl_NumWorkGroups)";
+    case spirv:
+        return spirv_asm {
+            result:$$uint3 = OpLoad builtin(NumWorkgroups:uint3);
+        };
+    }
+}
+
 // Test if any components is non-zero.
 
 __generic<T : __BuiltinType>