On Mon, 22 Jul 2024 16:36:25 GMT, Andrew Haley <a...@openjdk.org> wrote:
>>> Alternatively, `Klass::is_subtype_of()` can unconditionally perform linear >>> search over secondary_supers array. >>> >>> Even though I very much like to see table lookup written in C++ >>> (accompanying heavily optimized platform-specific MacroAssembler variants), >>> it would make C++ runtime even simpler. >> >> It would, but there is something to be said for being able to provide a fast >> "no" answer for interface membership. I'll agree it's probably not a huge >> difference. I guess `is_cloneable_fast()` exists only because searching the >> interfaces is slow. >> Also, if table lookup is written in C++ but not used, it will rot. >> Also also, `Klass::is_subtype_of()` is used for C1 runtime. > > Thinking about it some more, I don't really mind. There may be some virtue to > moving lookup_secondary_supers_table() to a comment in the back end(s), and > the expansion of population_count() is rather bloaty. > Also also, Klass::is_subtype_of() is used for C1 runtime. Can you elaborate, please? What I'm seeing in `Runtime1::generate_code_for()` for `slow_subtype_check` is a call into `MacroAssembler::check_klass_subtype_slow_path()`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/19989#discussion_r1688586602
