[spirv] Check parent class when setting contains-alias-component of "…

…this" (microsoft#4425)

When we handle `Load/Store` method of ByteAddressBuffer, we first load
the ByteAddressBuffer object if it is a reference of an alias variable.
`this` object is a reference of an alias variable if a
ByteAddressBuffer is a member of the class. The existing code checks
members of the class to determine if it has ByteAddressBuffer or not,
but it does not check its parent. Since we add all members of a parent
to its child class, we have to check members of the parent as well.
This commit fixes the issue and now `loadIfAliasVarRef(..)` properly
loads the access chain to ByteAddressBuffer.

For example,
```
// HLSL:
struct Base {
  ByteAddressBuffer buffer;
};

struct Child : Base {
  float load(in uint offset) {
    return asfloat(buffer.Load(offset));
  }
};

// Before:
%param_this = OpFunctionParameter %_ptr_Function_Child
%base = OpAccessChain %_ptr_Function_Base %param_this %uint_0
%ptr = OpAccessChain %_ptr_Function__ptr_Uniform_type_ByteAddressBuffer %base %int_0

OpAccessChain %_ptr_Uniform_uint %ptr %uint_0 ; <-- Error!!

// After:
%param_this = OpFunctionParameter %_ptr_Function_Child
%base = OpAccessChain %_ptr_Function_Base %param_this %uint_0
%ptr = OpAccessChain %_ptr_Function__ptr_Uniform_type_ByteAddressBuffer %base %int_0
%buffer = OpLoad %_ptr_Uniform_type_ByteAddressBuffer %ptr

OpAccessChain %_ptr_Uniform_uint %buffer %uint_0
```

tools/clang/lib/SPIRV/AstTypeProbe.cpp

@@ -996,6 +996,14 @@ bool isOrContainsAKindOfStructuredOrByteBuffer(QualType type) {
       if (isOrContainsAKindOfStructuredOrByteBuffer(field->getType()))
         return true;
     }
+
+    if (const auto *cxxDecl = type->getAsCXXRecordDecl()) {
+      for (const auto &base : cxxDecl->bases()) {
+        if (isOrContainsAKindOfStructuredOrByteBuffer(base.getType())) {
+          return true;
+        }
+      }
+    }
   }
   return false;
 }

tools/clang/test/CodeGenSPIRV/oo.inheritance.base-with-byte-address-buffer.hlsl

@@ -0,0 +1,30 @@
+// RUN: %dxc -T ps_6_0 -E main -fvk-use-dx-layout -fspv-reflect -fspv-target-env=vulkan1.1
+
+// We want to check that we correctly set "contains-alias-component" when the
+// class has a parent with ByteAddressBuffer, which later affects the result of
+// `loadIfAliasVarRef(..)` by letting it emit a load instruction of the pointer.
+// As a result, it prevents users of `loadIfAliasVarRef(..)` from just
+// referencing an access chain without a proper load.
+
+struct Base {
+  ByteAddressBuffer buffer;
+};
+
+struct Child : Base {
+  float load(in uint offset) {
+// CHECK:          %param_this = OpFunctionParameter %_ptr_Function_Child
+// CHECK:        [[base:%\w+]] = OpAccessChain %_ptr_Function_Base %param_this %uint_0
+// CHECK: [[ptrToBuffer:%\w+]] = OpAccessChain %_ptr_Function__ptr_Uniform_type_ByteAddressBuffer [[base]] %int_0
+
+// This test case is mainly intended to confirm that we emit the following instruction
+// CHECK: [[buffer:%\w+]] = OpLoad %_ptr_Uniform_type_ByteAddressBuffer [[ptrToBuffer]]
+
+// CHECK: OpAccessChain %_ptr_Uniform_uint [[buffer]] %uint_0
+    return asfloat(buffer.Load(offset));
+  }
+};
+
+void main(out float target : SV_Target) {
+  Child foo;
+  target = foo.load(0);
+}

tools/clang/unittests/SPIRV/CodeGenSpirvTest.cpp

@@ -699,6 +699,9 @@ TEST_F(FileTest, InheritanceCallMethodOfBase) {
   runFileTest("oo.inheritance.call.base.method.hlsl", Expect::Success,
               /* runValidation */ false);
 }
+TEST_F(FileTest, InheritanceBaseWithByteAddressBuffer) {
+  runFileTest("oo.inheritance.base-with-byte-address-buffer.hlsl");
+}
 TEST_F(FileTest, InheritanceCallMethodWithSameBaseMethodName) {
   runFileTest("oo.call.method.with.same.base.method.name.hlsl");
 }