Re: [PR debug/41535] reset debug insns affected by scheduling

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Fri, Oct 16, 2009 at 12:25 AM, Alexandre Oliva <aoliva@redhat.com> wrote:
> On Oct 15, 2009, Alexandre Oliva <aoliva@redhat.com> wrote:
>
>> This patch enables nondebug insns to “depend” on debug insns, but these
>> dependencies are handled in a special way: they don't stop the nondebug
>> insn from being scheduled. ?Rather, they enable the nondebug insn, once
>> scheduled, to quickly reset debug insns that remain as unresolved
>> dependencies.
>
>> To avoid using up more memory and complicating scheduler logic, I didn't
>> add more dependency lists.
>
> Turns out when I was about to finish composing the e-mail above, this
> idea occurred to me:
>
>> perhaps even discounting them in the list length counter.
>
> and it was pretty easy to implement and, surprise, it worked beautifully
> and far more easily and more efficient than the earlier patch!
>
> Also, Jakub kindly tested the patch on other arches and found
> -fmodulo-sched regressions: assertions failed that I'd put in there
> precisely to prevent “debug deps”. ?I'm yet to determine whether their
> presence might cause -fcompare-debug differences; it didn't for the
> testcases I tested, but they hardly exercised broad coverage. ?I'll
> start testing some optimized bootstrap-debugs and see if I run into any
> such problems. ?Fixing them will be for another patch, though.
>
> Here's the simplified patch I've regstrapped, so far, on
> x86_64-linux-gnu. ?Ok to install?
>

This may have caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41739


-- 
H.J.