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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Vladimir Makarov <vmakarov@redhat.com>
Cc: liuhongt <hongtao.liu@intel.com>,
	gcc-patches@gcc.gnu.org, linkw@gcc.gnu.org
Subject: Re: [PATCH] Only use NO_REGS in cost calculation when !hard_regno_mode_ok for GENERAL_REGS and mode.
Date: Thu, 25 May 2023 10:37:33 -0500	[thread overview]
Message-ID: <20230525153733.GL19790@gate.crashing.org> (raw)
In-Reply-To: <611d2da4-c692-39bb-8042-4415e7b6a194@redhat.com>

On Thu, May 25, 2023 at 10:29:47AM -0400, Vladimir Makarov wrote:
> 
> On 5/17/23 02:57, liuhongt wrote:
> >r14-172-g0368d169492017 replaces GENERAL_REGS with NO_REGS in cost
> >calculation when the preferred register class are not known yet.
> >It regressed powerpc PR109610 and PR109858, it looks too aggressive to use
> >NO_REGS when mode can be allocated with GENERAL_REGS.
> >The patch takes a step back, still use GENERAL_REGS when
> >hard_regno_mode_ok for mode and GENERAL_REGS, otherwise uses NO_REGS.
> >Kewen confirmed the patch fixed PR109858, I vefiried it also fixed 
> >PR109610.
> >
> >Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> >No big performance impact for SPEC2017 on icelake server.
> >Ok for trunk?
> >
> >gcc/ChangeLog:
> >
> >	* ira-costs.cc (scan_one_insn): Only use NO_REGS in cost
> >	calculation when !hard_regno_mode_ok for GENERAL_REGS and
> >	mode, otherwise still use GENERAL_REGS.
> 
> Thank you for the patch.  It looks good for me.  It is ok to commit it 
> into the trunk.

Thanks everyone involved for fixing this nasty regression!  Much
appreciated.


Segher

      reply	other threads:[~2023-05-25 15:38 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-17  6:57 liuhongt
2023-05-19 21:31 ` Jeff Law
2023-05-25 14:29 ` Vladimir Makarov
2023-05-25 15:37   ` Segher Boessenkool [this message]

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