Map `SV_InstanceID` to `gl_InstanceIndex-gl_BaseInstance` (#6468)

* Map `SV_InstanceID` to `gl_InstanceIndex-gl_BaseInstance`

* Fix ci.

1 files changed, 6 insertions, 0 deletions

diff --git a/source/slang/slang-emit-glsl.cpp b/source/slang/slang-emit-glsl.cpp
index 25dab3fb3..776c539b4 100644
--- a/source/slang/slang-emit-glsl.cpp
+++ b/source/slang/slang-emit-glsl.cpp
@@ -1791,6 +1791,12 @@ bool GLSLSourceEmitter::tryEmitGlobalParamImpl(IRGlobalParam* varDecl, IRType* v
         }
     }
 
+    if (varDecl->findDecoration<IRTargetBuiltinVarDecoration>())
+    {
+        // By default, we don't need to emit a definition for target builtin variables.
+        return true;
+    }
+
     // Do the default thing
     return false;
 }