Fix optix varying legalization. (shader-slang#6089)

* Fix optix varying legalization.

* Add test.

Author: csyonghe

source/slang/slang-ir-legalize-varying-params.cpp

@@ -1053,6 +1053,8 @@ struct CUDAEntryPointVaryingParamLegalizeContext : EntryPointVaryingParamLegaliz
         IRType* typeToFetch,
         IRBuilder* builder)
     {
+        if (auto ptrValType = tryGetPointedToType(builder, typeToFetch))
+            typeToFetch = ptrValType;
         if (auto structType = as<IRStructType>(typeToFetch))
         {
             List<IRInst*> fieldVals;

tests/cuda/optix-hit-attributes.slang

@@ -0,0 +1,15 @@
+//TEST:SIMPLE(filecheck=CHECK): -target cuda
+//CHECK: __global__ void __closesthit__closestHitShaderA
+struct RayPayload
+{
+    float4 color;
+};
+
+[shader("closesthit")]
+void closestHitShaderA(inout RayPayload payload, in BuiltInTriangleIntersectionAttributes attr)
+{
+    uint primitiveIndex = PrimitiveIndex();
+    float4 color = float4(0, 0, 0, 1);
+    color[primitiveIndex] = 1;
+    payload.color = color;
+}