Perform type legalization on StructuredBuffer element. (shader-slang#4767)

Author: csyonghe

source/slang/slang-legalize-types.cpp

@@ -1189,6 +1189,32 @@ LegalType legalizeTypeImpl(
                 legalElementType);
 
     }
+    else if (auto bufferType = as<IRHLSLStructuredBufferTypeBase>(type))
+    {
+        auto legalElementType = legalizeType(context, bufferType->getElementType());
+        IRInst* newElementType = nullptr;
+        switch (legalElementType.flavor)
+        {
+        case LegalType::Flavor::simple:
+            if (legalElementType.getSimple() == bufferType->getElementType())
+                return LegalType::simple(bufferType);
+            newElementType = legalElementType.getSimple();
+            break;
+        case LegalType::Flavor::none:
+            newElementType = context->getBuilder()->getIntType();
+            break;
+        default:
+            return LegalType::simple(bufferType);
+        }
+        ShortList<IRInst*> operands;
+        for (UInt i = 0; i < bufferType->getOperandCount(); i++)
+            operands.add(bufferType->getOperand(i));
+        operands[0] = newElementType;
+        return LegalType::simple(context->getBuilder()->getType(
+            bufferType->getOp(),
+            bufferType->getOperandCount(),
+            operands.getArrayView().getBuffer()));
+    }
     else if (isResourceType(type))
     {
         // We assume that any resource types not handled above

tests/language-feature/interfaces/empty-type-conformance.slang

@@ -0,0 +1,27 @@
+// Test that we allow empty type conformances.
+
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-dx11 -compute  -output-using-type
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute  -output-using-type
+
+interface TestInterface {
+    float sample();
+}
+struct TestImplementation : TestInterface {
+    float sample() {
+        return 1.0f;
+    }
+};
+
+//TEST_INPUT: set inBuffer = new StructuredBuffer<TestInterface>[new TestImplementation{}];
+StructuredBuffer<TestInterface> inBuffer;
+
+//TEST_INPUT: set outputBuffer = out ubuffer(data=[0 0 0 0], stride=4);
+RWStructuredBuffer<float> outputBuffer;
+
+[shader("compute")]
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+    // CHECK: 1.0
+    outputBuffer[0] = inBuffer[0].sample();
+}