From: Hongtao Liu <crazylht@gmail.com>
To: Uros Bizjak <ubizjak@gmail.com>
Cc: liuhongt <hongtao.liu@intel.com>,
gcc-patches@gcc.gnu.org, hjl.tools@gmail.com
Subject: Re: [PATCH] Adjust memory_move_cost for MASK_REGS when MODE_SIZE > 8.
Date: Fri, 31 Mar 2023 14:14:24 +0800 [thread overview]
Message-ID: <CAMZc-bwYsn0mvu7zVzKMacViSAj+t_ifhGkwCdT4E_CgRr6beA@mail.gmail.com> (raw)
In-Reply-To: <CAFULd4bvZoL3e=Mw9BRgnb4kBO7gjzx9jUwcBtMTCCPFzsgMRA@mail.gmail.com>
On Fri, Mar 31, 2023 at 1:57 PM Uros Bizjak <ubizjak@gmail.com> wrote:
>
> On Fri, Mar 31, 2023 at 7:11 AM liuhongt <hongtao.liu@intel.com> wrote:
> >
> > RA sometimes will use lowest the cost of the mode with all different regclasses
> > w/o check if it's hard_regno_mode_ok.
> > It's impossible to put modes whose size > 8 into MASK_REGS, ajdust the cost to
> > avoid potential performance issue.
>
> I was going to ask to open a PR in order to fix RA instead of the
> proposed workaround, but the patch just prevents a theoretical issue
> and follows the established practice with other regclasses. Perhaps
> these workarounds are not needed with the current RA, but this is a
> tangential issue which should be fixed for all regclasses.
Opened https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109351
>
> > Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> > Ok for trunk?
>
> OK.
>
> Thanks,
> Uros.
>
> >
> > gcc/ChangeLog:
> >
> > * config/i386/i386.cc (inline_memory_move_cost): Return 100
> > for MASK_REGS when MODE_SIZE > 8.
> > ---
> > gcc/config/i386/i386.cc | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> > index 2cc8e9548a9..2581b800a06 100644
> > --- a/gcc/config/i386/i386.cc
> > +++ b/gcc/config/i386/i386.cc
> > @@ -19847,9 +19847,12 @@ inline_memory_move_cost (machine_mode mode, enum reg_class regclass, int in)
> > index = 1;
> > break;
> > /* DImode loads and stores assumed to cost the same as SImode. */
> > - default:
> > + case 4:
> > + case 8:
> > index = 2;
> > break;
> > + default:
> > + return 100;
> > }
> >
> > if (in == 2)
> > --
> > 2.39.1.388.g2fc9e9ca3c
> >
--
BR,
Hongtao
prev parent reply other threads:[~2023-03-31 6:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-31 5:11 liuhongt
2023-03-31 5:57 ` Uros Bizjak
2023-03-31 6:14 ` Hongtao Liu [this message]
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