[mlir][spirv] Add missing interface storage classes in serializer

[mravishankar]

Thanks!

mlir/lib/Dialect/SPIRV/Serialization/Serializer.cpp

private:
   //===--------------------------------------------------------------------===//
 
   uint32_t getTypeID(Type type) const { return typeIDMap.lookup(type); }
 
   Type getVoidType() { return mlirBuilder.getNoneType(); }
 
   bool isVoidType(Type type) const { return type.isa<NoneType>(); }
 
-  /// Returns true if the given type is a pointer type to a struct in Uniform or
-  /// StorageBuffer storage class.
+  /// Returns true if the given type is a pointer type to a struct in some
+  /// interface storage class.
   bool isInterfaceStructPtrType(Type type) const;
 
   /// Main dispatch method for serializing a type. The result <id> of the
   /// serialized type will be returned as `typeID`.
   LogicalResult processType(Location loc, Type type, uint32_t &typeID);
 
   /// Method for preparing basic SPIR-V type serialization. Returns the type's
   /// opcode and operands for the instruction via `typeEnum` and `operands`.
Serializer::processGlobalVariableOp(spirv::GlobalVariableOp varOp) {
   }
   return success();
 }
 
 //===----------------------------------------------------------------------===//
 // Type
 //===----------------------------------------------------------------------===//
 
+// According to the SPIR-V spec "Validation Rules for Shader Capabilities":
+// "Composite objects in the StorageBuffer, PhysicalStorageBuffer, Uniform, and
+// PushConstant Storage Classes must be explicitly laid out."
 bool Serializer::isInterfaceStructPtrType(Type type) const {
   if (auto ptrType = type.dyn_cast<spirv::PointerType>()) {
-    auto storageClass = ptrType.getStorageClass();
-    if (storageClass == spirv::StorageClass::Uniform ||
-        storageClass == spirv::StorageClass::StorageBuffer) {
+    switch (ptrType.getStorageClass()) {
+    case spirv::StorageClass::PhysicalStorageBuffer:
+    case spirv::StorageClass::PushConstant:
+    case spirv::StorageClass::StorageBuffer:
+    case spirv::StorageClass::Uniform:
       return ptrType.getPointeeType().isa<spirv::StructType>();
+    default:
+      break;
     }
   }
   return false;
 }
 
 LogicalResult Serializer::processType(Location loc, Type type,
                                       uint32_t &typeID) {
   typeID = getTypeID(type);