From: Richard Biener <richard.guenther@gmail.com>
To: 钟云德 <zhong_1985624@163.com>
Cc: Zhongyunde <zhongyunde@huawei.com>,
Andrew Pinski <pinskia@gcc.gnu.org>,
"Weiwei (weiwei, Compiler)" <weiwei64@huawei.com>,
"hongtao.liu@intel.com" <hongtao.liu@intel.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,
"Zhangwen(Esan)" <zwzhangwen.zhang@huawei.com>
Subject: Re: Re: [PATCH] [PHIOPT] Add A ? B + CST : B match and simplify optimizations
Date: Wed, 9 Nov 2022 09:00:34 +0100 [thread overview]
Message-ID: <CAFiYyc0QVrqhM9PvZjenyrx4Ugkx+fHQwiLXM3-4k_5TtX-7Aw@mail.gmail.com> (raw)
In-Reply-To: <c63b512.41cf.18457f02a0c.Coremail.zhong_1985624@163.com>
[-- Attachment #1: Type: text/plain, Size: 3996 bytes --]
On Tue, Nov 8, 2022 at 4:51 PM 钟云德 <zhong_1985624@163.com> wrote:
> At 2022-11-08 22:58:34, "Richard Biener" <richard.guenther@gmail.com>
> wrote:
>
> >On Sat, Nov 5, 2022 at 10:03 AM Zhongyunde via Gcc-patches
> ><gcc-patches@gcc.gnu.org> wrote:
> >>
> >>
> >> > -----Original Message-----
> >> > From: Andrew Pinski [mailto:pinskia@gcc.gnu.org]
> >> > Sent: Saturday, November 5, 2022 2:34 PM
> >> > To: Zhongyunde <zhongyunde@huawei.com>
> >> > Cc: hongtao.liu@intel.com; gcc-patches@gcc.gnu.org; Zhangwen(Esan)
> >> > <zwzhangwen.zhang@huawei.com>; Weiwei (weiwei, Compiler)
> >> > <weiwei64@huawei.com>; zhong_1985624@163.com
> >> > Subject: Re: [PATCH] [PHIOPT] Add A ? B + CST : B match and simplify
> >> > optimizations
> >> >
> >> > On Fri, Nov 4, 2022 at 11:17 PM Zhongyunde <zhongyunde@huawei.com>
> >> > wrote:
> >> > >
> >> > > hi,
> >> > > This patch is try to fix the issue
> >> > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107190,
> >> > > would you like to give me some suggestion, thanks.
> >> >
> >> > This seems like a "simplified" version of
> >> > https://gcc.gnu.org/pipermail/gcc-patches/2021-November/584411.html
> >> > which just handles power of 2 constants where we know the cond will be
> >> > removed.
> >> > We could do even more "simplified" of 1 if needed really.
> >> > What is the IR before PHI-OPT? Is it just + 1?
> >>
> >> Thanks for your attention. It is + 4294967296 before PHI-OPT (See detail https://gcc.godbolt.org/z/6zEc6ja1z)
> >> So we should keep matching the power of 2 constants ?
> >>
> >> > Also your pattern can be simplified to use integer_pow2p in the match part
> >> > instead of INTEGER_CST.
> >> >
> >> Apply your comment, thanks
> >
> >How does the patch fix the mentioned bug? match.pd patterns should make things
> >"simpler" but x + (a << C') isn't simpler than a ? x + C : x. It
> >looks you are targeting
> >PHI-OPT here, so maybe instead extend value_replacement to handle this case,
> >it does look similar to the case with neutral/absorbing element there?
> >
> >Richard.
>
> Thanks. This patch try to fix the 1st issued mentioned in 107090 – [aarch64] sequence logic should be combined with mul and umulh (gnu.org) <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107090>
> Sure, I'll take a look at the function value_replacement.
> I have also noticed that the function of two_value_replacement is very close to patch I want to achieve, and it may be easy to extend.
> It seems can be expressed equally in match.pd (called by match_simplify_replacement), so how do we
> choose where to implement may be better?
>
>
I think that if we realize that we don't want a simplification to always
apply (like by checking
for canonicalize_math_p ()), then we should look for a pass which is a good
fit and since
you add the pattern to trigger a PHI-OPT optimization that looked like an
obvious choice ...
```
>
> /* Do the replacement of conditional if it can be done. */ if (!early_p && !diamond_p && two_value_replacement (bb, bb1, e2, phi, arg0, arg1)) cfgchanged = true; else if (!diamond_p && match_simplify_replacement (bb, bb1, e1, e2, phi, arg0, arg1, early_p)) cfgchanged = true;
>
> ```
> >> > Thanks, >> > Andrew >> >>
>
>
next prev parent reply other threads:[~2022-11-09 8:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-05 21:44 [PATCH] riscv: implement TARGET_MODE_REP_EXTENDED Philipp Tomsich
2022-09-06 11:39 ` Alexander Monakov
2022-09-16 23:48 ` Jeff Law
2022-09-17 7:59 ` Palmer Dabbelt
2022-11-04 23:00 ` Philipp Tomsich
2022-11-05 6:16 ` [PATCH] [PHIOPT] Add A ? B + CST : B match and simplify optimizations Zhongyunde
2022-11-05 6:34 ` Andrew Pinski
2022-11-05 9:03 ` Zhongyunde
2022-11-08 14:58 ` Richard Biener
2022-11-08 15:51 ` 钟云德
2022-11-09 8:00 ` Richard Biener [this message]
2022-11-07 13:55 ` [PATCH] riscv: implement TARGET_MODE_REP_EXTENDED Alexander Monakov
2022-11-08 23:45 ` Philipp Tomsich
2022-11-09 17:21 ` Alexander Monakov
2022-11-20 16:09 ` Jeff Law
2022-11-21 13:49 ` Alexander Monakov
2022-11-21 14:56 ` Jeff Law
2022-11-21 15:33 ` Alexander Monakov
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