P4
JavaCallArguments has this code and comment:
- // Helper for push_oop and the like. The value argument is a
- // "handle" that refers to an oop. We record the address of the
- // handle rather than the designated oop. The handle is later
- // resolved to the oop by parameters(). This delays the exposure of
- // naked oops until it is GC-safe.
- template<typename T>
- inline int push_oop_impl(T handle, int size) {
- // JNITypes::put_obj expects an oop value, so we play fast and
- // loose with the type system. The cast from handle type to oop
- // *must* use a C-style cast. In a product build it performs a
- // reinterpret_cast. In a debug build (more accurately, in a
- // CHECK_UNHANDLED_OOPS build) it performs a static_cast, invoking
- // the debug-only oop class's conversion from void* constructor.
- JNITypes::put_obj((oop)handle, _value, size); // Updates size.
- return size; // Return the updated size.
- }
The type T is either an oop* or jobject (JNI handle). This puts something that isn't an oop inside an oop.
I propose that we don't do this. Instead we could pass the handle (address containing the oop), and then in put_obj convert that address to an intptr_t, which matches well with the `to` argument of those functions.
- // Helper for push_oop and the like. The value argument is a
- // "handle" that refers to an oop. We record the address of the
- // handle rather than the designated oop. The handle is later
- // resolved to the oop by parameters(). This delays the exposure of
- // naked oops until it is GC-safe.
- template<typename T>
- inline int push_oop_impl(T handle, int size) {
- // JNITypes::put_obj expects an oop value, so we play fast and
- // loose with the type system. The cast from handle type to oop
- // *must* use a C-style cast. In a product build it performs a
- // reinterpret_cast. In a debug build (more accurately, in a
- // CHECK_UNHANDLED_OOPS build) it performs a static_cast, invoking
- // the debug-only oop class's conversion from void* constructor.
- JNITypes::put_obj((oop)handle, _value, size); // Updates size.
- return size; // Return the updated size.
- }
The type T is either an oop* or jobject (JNI handle). This puts something that isn't an oop inside an oop.
I propose that we don't do this. Instead we could pass the handle (address containing the oop), and then in put_obj convert that address to an intptr_t, which matches well with the `to` argument of those functions.
