Implement specialization constant support in numthreads / local_size (#5963)

* Allow using specialization constants in numthreads attribute

* Add support for GLSL local_size_x_id syntax

* Fix overeager specialization constant parsing

* Add diagnostics for specialization constant numthreads

* Remove unused variable

* Fix local_size_x_id not finding existing specialization constant

* Allow materializeGetWorkGroupSize to reference specialization constants

* Use SpvOpExecutionModeId for modes that require it

* Cleanup specialization constant numthreads code

* Add tests for specialization constant work group sizes

* Fix implicit Slang::Int -> int32_t cast

* Fix querying thread group size in reflection API

---------

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

1 files changed, 13 insertions, 0 deletions

diff --git a/source/slang/slang-ir-util.cpp b/source/slang/slang-ir-util.cpp
index c753600a7..d05e1db7d 100644
--- a/source/slang/slang-ir-util.cpp
+++ b/source/slang/slang-ir-util.cpp
@@ -1973,4 +1973,17 @@ IRType* getIRVectorBaseType(IRType* type)
     return as<IRVectorType>(type)->getElementType();
 }
 
+Int getSpecializationConstantId(IRGlobalParam* param)
+{
+    auto layout = findVarLayout(param);
+    if (!layout)
+        return 0;
+
+    auto offset = layout->findOffsetAttr(LayoutResourceKind::SpecializationConstant);
+    if (!offset)
+        return 0;
+
+    return offset->getOffset();
+}
+
 } // namespace Slang