Messages in this thread | | | From | Nick Desaulniers <> | Date | Tue, 9 Nov 2021 14:15:38 -0800 | Subject | Re: [PATCH 20/22] x86,word-at-a-time: Remove .fixup usage |
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On Tue, Nov 9, 2021 at 2:11 PM Peter Zijlstra <peterz@infradead.org> wrote: > > On Tue, Nov 09, 2021 at 01:25:47PM -0800, Nick Desaulniers wrote: > > On Tue, Nov 9, 2021 at 1:21 PM Peter Zijlstra <peterz@infradead.org> wrote: > > > > > > On Tue, Nov 09, 2021 at 12:59:12PM -0800, Bill Wendling wrote: > > > > > > > > Adding attributes to labels shouldn't be difficult, as you mention. In > > > > the case of cold/hot, it's adjusting some of the metadata that already > > > > exists on some basic blocks. It might be enough to allow the normal > > > > block placement algorithms to move the hot and cold blocks around for > > > > us. The question becomes how many attributes does GCC allow on labels? > > > > > > I'm aware of 3: unused, hot, cold. Also: > > > > > > https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html > > > > Re: unused: > > Being able to selectively disable -Wunused-label via > > __attribute__((unused)); seems useful, too. > > kernel/sched/fair.c:done: __maybe_unused; > > Yes it is ;-)
Ah, that's already supported: https://godbolt.org/z/aa76aexnv, so it's just hot/cold that could be implemented next. -- Thanks, ~Nick Desaulniers
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