Another epic optimiser failure

Jonathan Wakely jwakely.gcc@gmail.com
Sat May 27 22:46:10 GMT 2023


On Sat, 27 May 2023 at 23:03, Stefan Kanthak <stefan.kanthak@nexgo.de> wrote:
>
> "Andrew Pinski" <pinskia@gmail.com> wrote:
>
> > On Sat, May 27, 2023 at 2:38 PM Stefan Kanthak <stefan.kanthak@nexgo.de> wrote:
> >>
> >> "Jakub Jelinek" <jakub@redhat.com> wrote, completely clueless:
> >>
> >>> On Sat, May 27, 2023 at 11:04:11PM +0200, Stefan Kanthak wrote:
> >>>> OUCH: popcnt writes the WHOLE result register, there is ABSOLUTELY
> >>>>       no need to clear it beforehand nor to clear the higher 24 bits
> >>>>       afterwards!
> >>>
> >>> Except that there is.  See https://gcc.gnu.org/PR62011 for details.
> >>
> >> GUESS WHY I EXPLICITLY WROTE
> >>
> >> | JFTR: before GCC zealots write nonsense: see -march= or -mtune=
> >>
> >> NOT AMUSED ABOUT YOUR CRYING INCOMPETENCE!
> >
> > So you want to complain about GCC knowing about an Intel performance errata????
>
> Ever heard about cargo cult?
>
> Read the options I used CAREFULLY
>
> | gcc -m32 -march=alderlake -O3
> | gcc -m32 -march=sapphirerapids -O3
> | gcc -m32 -mpopcnt -mtune=sapphirerapids -O3
>
> > If you read that bug report, you would have learned why the zeroing is
> > done. I am sorry you hate GCC for actually following advice from the
> > processor maker after all.
>
> HSD146 does NOT apply to Alder Lake or Sapphire Rapids!
>
> NOT AMUSED ABOUT YOUR INCOMPETENCE TOO!
> Stefan

File a proper bug report then, instead of subjecting this mailing list
to your clown show.


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