Re: [PATCH] [RTL] Relax CSE check to set REG_EQUAL notes.

[Alex Velenko <Alex dot Velenko at arm dot com>]

On 24/04/15 02:16, Jeff Law wrote:
> On 04/10/2015 03:14 AM, Alex Velenko wrote:
> > On 09/03/15 17:40, Jeff Law wrote:
> > > On 03/09/15 03:53, Steven Bosscher wrote:
> > > > On Wed, Mar 4, 2015 at 12:09 PM, Alex Velenko wrote:
> > > > > For example, in arm testcase pr43920-2.c, CSE previously decided not
> > > > > to put
> > > > > an "obvious" note on insn 9, as set value was the same as note value.
> > > > > At the same time, other insns set up as -1 were set up through a
> > > > > register
> > > > > and did get a note:
> > > >
> > > > ...which is the point of the REG_EQUAL notes. In insn 8 there is a
> > > > REG_EQUAL note to show that the value of r111 is known. In insn 9 the
> > > > known value is, well, known from SET_SRC so there is no need for a
> > > > REG_EQUAL note. Adding REG_EQUAL notes in such cases is just wasteful.
> > > RIght.  I'd rather look into why later passes aren't discovering
> > > whatever equivalences are important rather than adding the redundant
> > > notes.
> > >
> > > Regardless, I think this is a gcc-6 issue, so I'm not likely to look at
> > > it in the immediate future.
> > >
> > > jeff
> > Hi Jeff,
> > I reworked the patch to satisfy your preference.
> >
> > This patch enables cfgcleanup.c to use const int rtx as REG_EQUAL notes.
> > For example, this benefits Jump2 to find extra optimisation opportunities.
> > This patch fixes gcc.target/arm/pr43920-2.c for arm-none-eabi.
> >
> > Bootstraped on x86, run full regression run on arm-none-eabi and
> > aarch64-none-elf.
> >
> > Is this patch ok?
> >
> > gcc/
> >
> > 2015-03-17  Alex Velenko  <Alex.Velenko@arm.com>
> >
> >       * cfgcleanup.c (can_replace_by): Use const int rtx of single set as
> >       REG_EQUAL note.
> Now I finally see this in my queue.  I recalled the discussion around
> whether or not to add the redundant notes, but hadn't had a chance to
> look at the updated patch.
>
> AFAICT, this is redundant with Shiva's patch, right?
>
> jeff

Hi Jeff,
Yes, you are correct, this patch is now redundant.
Kind regards,
Alex