[SPIRV] Fix layout rule for BufferPointer pointee type (#7956)

When picking the layout rule for the Pointee type of a BufferPointer, we
are using the layout for the object containing the pointer, but that is
incorrect.

The layout for the PhysicalStorageBuffer should always follow the
storage buffer layout rules.

Fixes #7893

Author: s-perron

tools/clang/lib/SPIRV/LowerTypeVisitor.cpp

@@ -836,12 +836,10 @@ const SpirvType *LowerTypeVisitor::lowerVkTypeInVkNamespace(
     }
 
     QualType realType = hlsl::GetHLSLResourceTemplateParamType(type);
-    if (rule == SpirvLayoutRule::Void) {
-      rule = spvOptions.sBufferLayoutRule;
-    }
     visitedTypeStack.push_back(type);
 
-    const SpirvType *spirvType = lowerType(realType, rule, llvm::None, srcLoc);
+    const SpirvType *spirvType =
+        lowerType(realType, spvOptions.sBufferLayoutRule, llvm::None, srcLoc);
     const auto *pointerType = spvContext.getPointerType(
         spirvType, spv::StorageClass::PhysicalStorageBuffer);
     spvContext.registerForwardReference(type, pointerType);

tools/clang/test/CodeGenSPIRV/vk.buffer-pointer.different-storage-class.hlsl

@@ -0,0 +1,29 @@
+// RUN: %dxc -spirv -E main -T cs_6_7 %s | FileCheck %s
+
+
+struct Foo {
+    int val[4];
+};
+
+// CHECK: OpDecorate [[ARRAY_INT_4:%[_0-9A-Za-z]*]] ArrayStride 4
+// CHECK: [[TYPE_FOO:%[_0-9A-Za-z]*]] = OpTypeStruct [[ARRAY_INT_4]]
+// CHECK: [[PTR_PHYS_BUF_FOO:%[_0-9A-Za-z]*]] = OpTypePointer PhysicalStorageBuffer [[TYPE_FOO]]
+// CHECK: [[TYPE_TEST_STRUCT:%[_0-9A-Za-z]*]] = OpTypeStruct [[PTR_PHYS_BUF_FOO]] %_ptr_PhysicalStorageBuffer_int
+// CHECK: [[PTR_UNIFORM_TYPE_TEST:%[_0-9A-Za-z]*]] = OpTypePointer Uniform [[TYPE_TEST_STRUCT]]
+// CHECK: [[TEST_VAR:%[_0-9A-Za-z]*]] = OpVariable [[PTR_UNIFORM_TYPE_TEST]] Uniform
+cbuffer Test {
+    // The layout of `Foo` for the Buffer pointer should be the layout for
+    // the storage buffer, even if the pointer is in a cbuffer.
+    vk::BufferPointer<Foo> fooBuf;
+    vk::BufferPointer<int> outBuf;
+};
+
+
+
+[numthreads(256, 1, 1)]
+void main(in uint3 threadId : SV_DispatchThreadID) {
+// CHECK: [[FOO_BUF_ACCESS_CHAIN:%[_0-9A-Za-z]*]] = OpAccessChain %_ptr_Uniform__ptr_PhysicalStorageBuffer_Foo [[TEST_VAR]] %int_0
+// CHECK: [[FOO_BUF_LOAD:%[_0-9A-Za-z]*]] = OpLoad %_ptr_PhysicalStorageBuffer_Foo [[FOO_BUF_ACCESS_CHAIN]]
+    int val = fooBuf.Get().val[0];
+    outBuf.Get() = val;
+}