On Tue, 7 Sep 2021 23:29:10 GMT, Ioi Lam <ik...@openjdk.org> wrote:
>> Leo Korinth has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> First update
>>
>> * Change backing type of ResourceObj::allocation_type to be u8. Also
>> remove no longer needed mask and explicit zero value of STACK_OR_EMBEDDED
>> value.
>>
>> * Now setting allocation type with set_type() with assert.
>
> src/hotspot/share/memory/allocation.hpp line 439:
>
>> 437: void* operator new(size_t size, const std::nothrow_t&
>> nothrow_constant) throw() {
>> 438: address res = (address)resource_allocate_bytes(size,
>> AllocFailStrategy::RETURN_NULL);
>> 439: DEBUG_ONLY(if (res != NULL) _thread_last_allocated =
>> RESOURCE_AREA;)
>
> Maybe we should also guard against the possibility of nested allocations,
> which may trash `_thread_last_allocated`?
>
>
> #define PUSH_RESOURCE_OBJ_ALLOC_TYPE(t) \
> assert(_thread_last_allocated == STACK_OR_EMBEDDED, "must not be nested"); \
> DEBUG_ONLY(_thread_last_allocated = t); \
>
> ...
> if (res != NULL) {
> PUSH_RESOURCE_OBJ_ALLOC_TYPE(RESOURCE_AREA);
> }
>
>
> Similarly, the `ResourceObj` constructor should use a corresponding
> `POP_RESOURCE_OBJ_ALLOC_TYPE` macro.
I added a `set_type` method that ensures that the `_thread_last_allocated`
always transition over a `STACK_OR_EMBEDDED`. I did *not* create a PUSH/POP
macro pair because i believe it would give the false impression that we are
doing a stack operation.
Other than that I also made `allocation_type` use a `u8` as backing type. I
also removed the now unused `allocation_mask` and the now unimportant detail
that `STACK_OR_EMBEDDED = 0`.
-------------
PR: https://git.openjdk.java.net/jdk/pull/5387
