speculation_barrier for MIPS needs sync+jr.hb (r2+),
so we implement __speculation_barrier in libgcc, like arm32 does.
gcc/ChangeLog:
* config/mips/mips-protos.h (mips_emit_speculation_barrier): New
prototype.
* config/mips/mips.cc (speculation_barrier_libfunc): New static
YunQiang Su writes:
> speculation_barrier for MIPS needs sync+jr.hb (r2+),
> so we implement __speculation_barrier in libgcc, like arm32 does.
Looks reasonable, but do you have a source for the fallback
pre-r2 handling? (Thanks for adding that btw, since I realise
it's not your focus here.)
Nit
On Wed, 3 May 2023, Richard Sandiford wrote:
> > speculation_barrier for MIPS needs sync+jr.hb (r2+),
> > so we implement __speculation_barrier in libgcc, like arm32 does.
>
> Looks reasonable, but do you have a source for the fallback
> pre-r2 handling? (Thanks for adding that btw, since I real
> 2023年5月3日 22:04，Maciej W. Rozycki 写道：
>
> On Wed, 3 May 2023, Richard Sandiford wrote:
>
>>> speculation_barrier for MIPS needs sync+jr.hb (r2+),
>>> so we implement __speculation_barrier in libgcc, like arm32 does.
>>
>> Looks reasonable, but do you have a source for the fallback
>> pre-r
On Wed, 3 May 2023, Jiaxun Yang wrote:
> Since it’s possible to run R2- binary on R2+ processor, we’d better find a
> semantic that do eliminate speculation on all processors. While SSNOPs
> on R2+ processors is pretty much undefined, there is no guarantee that
> SSNOP sequence can eliminate specu
> 2023年5月7日 18:34，Maciej W. Rozycki 写道：
>
> On Wed, 3 May 2023, Jiaxun Yang wrote:
>
>> Since it’s possible to run R2- binary on R2+ processor, we’d better find a
>> semantic that do eliminate speculation on all processors. While SSNOPs
>> on R2+ processors is pretty much undefined, there is
On Sun, 7 May 2023, Jiaxun Yang wrote:
> > Both EHB and J[AL]R.HB are backwards compatible however (except for an
> > obscure 4Kc J[AL]R.HB erratum I came across once and which may be no
> > longer relevant), so I think the legacy sequence ought to just return via
> > JR.HB as well, therefore p
