On Tue, 27 Jun 2023 12:59:59 GMT, Stefan Karlsson <stef...@openjdk.org> wrote:
>> This is another version of PR https://github.com/openjdk/jdk/pull/14659 but >> I've added a pointer delta function in globalDefinitions.hpp to use for >> these pointer diff calculations that return int everywhere. If the name is >> agreeable, I'll fix the other cases of this like this. It's better than raw >> casts. >> Tested with tier1-4. > > src/hotspot/share/code/codeBlob.inline.hpp line 36: > >> 34: inline const ImmutableOopMap* CodeBlob::oop_map_for_slot(int slot, >> address return_address) const { >> 35: assert(_oop_maps != nullptr, "nope"); >> 36: return _oop_maps->find_map_at_slot(slot, delta_as_int((intptr_t) >> return_address, (intptr_t) code_begin())); > > Is this the only usage of `delta_as_int` that operates on `intptr_t`? If we > remove the casts then all usages would operate on pointers. Maybe this is an > indication that we only need a `pointer_delta_as_int` function, to go hand in > hand with the other `pointer_delta` functions? Hm. Maybe this would be ok. Our original idea was to make it T* not T until this cast. I don't know how many other cases there are that I haven't gotten to yet. But it would eliminate a cast, so that's good (unless these aren't the same). Some instances have ptr - constant that gets promoted I think. The reason we didn't pick pointer_delta_as_int because pointer_delta has different semantics. pointer_delta insists on positive results. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/14675#discussion_r1243892244
