Make various parameters and return types require specialization when targeting WGSL (shader-slang#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 shader-slang#5228, issue shader-slang#5278 and issue shader-slang#5288 by enabling specialized functions
to be generated in these cases, in order to work around these constraints.

Author: aleino-nv

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
 {

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

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

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

tests/bugs/mutating/resource-specialization-inout.slang

@@ -1,7 +1,6 @@
 // Bug related to resource specialization on unused resource typed fields.
 
 //TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj
-//DISABLE_TEST(compute):COMPARE_COMPUTE_EX:-wgpu
 
 //TEST_INPUT: Texture2D(size=4, content = one):name t2D
 Texture2D t2D;

tests/compute/func-resource-param.slang

@@ -8,7 +8,6 @@
 //TEST(compute, vulkan):COMPARE_COMPUTE_EX:-dx12 -compute -shaderobj
 //TEST(compute, vulkan):COMPARE_COMPUTE_EX:-vk -compute -shaderobj
 //TEST(compute, vulkan):COMPARE_COMPUTE_EX:-cpu -compute -shaderobj
-//DISABLE_TEST(compute):COMPARE_COMPUTE:-wgpu
 
 //NO_TEST:SIMPLE:-target glsl -entry computeMain -stage compute -validate-ir -dump-ir
 

tests/expected-failure-github.txt

@@ -32,7 +32,6 @@ tests/bugs/gh-3980.slang.7 syn (wgpu)
 tests/bugs/gh-471.slang.1 syn (wgpu)
 tests/bugs/gh-518.slang.2 syn (wgpu)
 tests/bugs/gh-566.slang.1 syn (wgpu)
-tests/bugs/mutating/resource-specialization-inout.slang.1 syn (wgpu)
 tests/bugs/nested-switch.slang.3 syn (wgpu)
 tests/bugs/obfuscate-specialization-naming.slang.2 syn (wgpu)
 tests/bugs/op-assignment-unify-mat.slang.4 syn (wgpu)
@@ -51,7 +50,6 @@ tests/compute/compile-time-loop.slang.2 syn (wgpu)
 tests/compute/constexpr.slang.2 syn (wgpu)
 tests/compute/discard-stmt.slang.2 syn (wgpu)
 tests/compute/func-param-legalize.slang.1 syn (wgpu)
-tests/compute/func-resource-param.slang.4 syn (wgpu)
 tests/compute/global-init.slang.2 syn (wgpu)
 tests/compute/interface-shader-param-in-struct.slang.4 syn (wgpu)
 tests/compute/interface-shader-param.slang.5 syn (wgpu)
@@ -98,5 +96,4 @@ tests/language-feature/types/opaque/return-opaque-type-in-struct.slang.2 syn (wg
 tests/language-feature/types/opaque/return-opaque-type.slang.1 syn (wgpu)
 tests/metal/groupshared-threadlocal-same-parameter.slang.4 syn (wgpu)
 tests/optimization/func-resource-result/func-resource-result-complex.slang.2 syn (wgpu)
-tests/optimization/func-resource-result/func-resource-result-simple.slang.4 syn (wgpu)
 tests/pipeline/compute/compute-system-values.slang.3 syn (wgpu)

tests/optimization/func-resource-result/func-resource-result-simple.slang

@@ -4,7 +4,6 @@
 //TEST(compute, vulkan):COMPARE_COMPUTE_EX:-vk -compute -shaderobj
 //TEST(compute):COMPARE_COMPUTE_EX:-cpu -compute -shaderobj
 //TEST(compute):COMPARE_COMPUTE:-slang -shaderobj -mtl
-//DISABLE_TEST(compute):COMPARE_COMPUTE_EX:-wgpu
 
 // Test that a function that returns a resource type can be
 // compiled for targets that don't natively support resource