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Re: [PATCH, i386]: Improve STV conversion of shifts
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Uros Bizjak <ubizjak at gmail dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 30 Aug 2019 09:22:24 +0200
- Subject: Re: [PATCH, i386]: Improve STV conversion of shifts
- References: <CAFULd4Z88+aey62UENVeSQCzCx+ev7-AYbCgW-ox63qa7R6TtA@mail.gmail.com> <CAFULd4Yaoa3h4vtd=x0yposto8hsLouLAwSdF5P2thG9CuVC=A@mail.gmail.com>
On Thu, Aug 29, 2019 at 9:54 AM Uros Bizjak <ubizjak@gmail.com> wrote:
>
> On Wed, Aug 28, 2019 at 5:12 PM Uros Bizjak <ubizjak@gmail.com> wrote:
> >
> > Attached patch improves costing for STV shifts and corrects reject
> > condition for out of range shift count operands.
> >
> > 2019-08-28 Uroš Bizjak <ubizjak@gmail.com>
> >
> > * config/i386/i386-features.c
> > (general_scalar_chain::compute_convert_gain):
> > Correct cost for double-word shifts.
> > (general_scalar_to_vector_candidate_p): Reject count operands
> > greater or equal to mode bitsize.
> >
> > Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.
> >
> > Committed to mainline SVN.
>
> Ouch... I mixed up patches and actually committed the patch that
> removes maximum from cost of sse<->int moves.
>
> I can leave the patch for a day, so we can see the effects of the cost
> change, and if the patch creates problems, I'll revert it.
Regresses gromacs and namd quite a bit on Haswell, also perl in SPEC 2000.
I guess we should try understand why rather than reverting immediately
(I'd leave it in at least another few days to get more testers pick up the
rev.).
Richard.
> Sorry for the mixup,
> Uros.