Make various parameters and return types require specialization when targeting WGSL (#5483)

Structured buffer types translate to array types in the WGSL emitter.
WGSL doesn't allow passing runtime-sized arrays to functions.
Similarly for pointers to texture handles.
Also, structured buffers (runtime-sized arrays) cannot be returned in WGSL.

This closes issue #5228, issue #5278 and issue #5288 by enabling specialized functions
to be generated in these cases, in order to work around these constraints.

4 files changed, 29 insertions, 2 deletions

diff --git a/source/slang/slang-compiler.h b/source/slang/slang-compiler.h
index 624e6ec3b..9fea93b7c 100644
--- a/source/slang/slang-compiler.h
+++ b/source/slang/slang-compiler.h
@@ -1958,6 +1958,9 @@ bool isCUDATarget(TargetRequest* targetReq);
 // Are we generating code for a CPU target
 bool isCPUTarget(TargetRequest* targetReq);
 
+/// Are we generating code for the WebGPU API?
+bool isWGPUTarget(TargetRequest* targetReq);
+
 /// A request to generate output in some target format.
 class TargetRequest : public RefObject
 {
diff --git a/source/slang/slang-ir-specialize-resources.cpp b/source/slang/slang-ir-specialize-resources.cpp
index 6aca4bbc7..56f468ac7 100644
--- a/source/slang/slang-ir-specialize-resources.cpp
+++ b/source/slang/slang-ir-specialize-resources.cpp
@@ -67,7 +67,10 @@ struct ResourceParameterSpecializationCondition : FunctionCallSpecializeConditio
             else
                 return isIllegalGLSLParameterType(type);
         }
-
+        else if (isWGPUTarget(targetRequest))
+        {
+            return isIllegalWGSLParameterType(type);
+        }
 
         // For now, we will not treat any other parameters as
         // needing specialization, even if they use resource
@@ -1220,7 +1223,7 @@ bool specializeResourceOutputs(
     HashSet<IRFunc*>& unspecializableFuncs)
 {
     auto targetRequest = codeGenContext->getTargetReq();
-    if (isD3DTarget(targetRequest) || isKhronosTarget(targetRequest))
+    if (isD3DTarget(targetRequest) || isKhronosTarget(targetRequest) || isWGPUTarget(targetRequest))
     {
     }
     else
@@ -1354,4 +1357,10 @@ bool isIllegalSPIRVParameterType(IRType* type, bool isArray)
     }
     return false;
 }
+
+bool isIllegalWGSLParameterType(IRType* type)
+{
+    return isIllegalGLSLParameterType(type);
+}
+
 } // namespace Slang
diff --git a/source/slang/slang-ir-specialize-resources.h b/source/slang/slang-ir-specialize-resources.h
index 911fa3bb9..feb61c026 100644
--- a/source/slang/slang-ir-specialize-resources.h
+++ b/source/slang/slang-ir-specialize-resources.h
@@ -26,5 +26,6 @@ bool specializeResourceUsage(CodeGenContext* codeGenContext, IRModule* irModule)
 
 bool isIllegalGLSLParameterType(IRType* type);
 bool isIllegalSPIRVParameterType(IRType* type, bool isArray);
+bool isIllegalWGSLParameterType(IRType* type);
 
 } // namespace Slang
diff --git a/source/slang/slang-type-layout.cpp b/source/slang/slang-type-layout.cpp
index a63d6401e..e36e54531 100644
--- a/source/slang/slang-type-layout.cpp
+++ b/source/slang/slang-type-layout.cpp
@@ -2397,6 +2397,20 @@ bool isCUDATarget(TargetRequest* targetReq)
     }
 }
 
+bool isWGPUTarget(TargetRequest* targetReq)
+{
+    switch (targetReq->getTarget())
+    {
+    default:
+        return false;
+
+    case CodeGenTarget::WGSL:
+    case CodeGenTarget::WGSLSPIRV:
+    case CodeGenTarget::WGSLSPIRVAssembly:
+        return true;
+    }
+}
+
 SourceLanguage getIntermediateSourceLanguageForTarget(TargetProgram* targetProgram)
 {
     // If we are emitting directly, there is no intermediate source language