From: Jeff Law <jeffreyalaw@gmail.com>
To: Navid Rahimi <navidrahimi@microsoft.com>,
Navid Rahimi via Gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH][WIP] PR tree-optimization/101808 Boolean comparison simplification
Date: Tue, 23 Nov 2021 12:14:20 -0700 [thread overview]
Message-ID: <0320449b-433b-1e27-732f-4fd3e17b76b6@gmail.com> (raw)
In-Reply-To: <BN6PR21MB01628850C46353EE1EB0DBE4A3609@BN6PR21MB0162.namprd21.prod.outlook.com>
On 11/23/2021 11:34 AM, Navid Rahimi via Gcc-patches wrote:
> Hi GCC community,
>
> I wanted you take a quick look at this patch to solve this bug [1]. This is the code example for the optimization [2] which does include a link to proof of each different optimization.
>
> I think it should be possible to use simpler approach than what Andrew has used here [3].
>
> P.S. Tested and verified on Linux x86_64.
>
> 1) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101808
> 2) https://compiler-explorer.com/z/Gc448eE3z
> 3) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101808#c1
Don't those match.pd patterns make things worse? We're taking a single
expression evaluation (the conditional) and turning it into two logicals
AFAICT.
For the !x expression, obviously if x is a constant, then we can
compute that at compile time and we're going from a single conditional
to a single logical which is probably a win, but that's not the case
with this patch AFAICT.
jeff
next prev parent reply other threads:[~2021-11-23 19:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 18:34 Navid Rahimi
2021-11-23 19:14 ` Jeff Law [this message]
2021-11-23 19:33 ` Andrew Pinski
2021-11-23 19:55 ` [EXTERNAL] " Navid Rahimi
2021-11-23 20:03 ` Jeff Law
2021-11-29 23:51 ` Navid Rahimi
2021-12-03 15:43 ` Jeff Law
2021-11-23 19:42 ` Navid Rahimi
2021-11-23 20:02 ` Jeff Law
2021-11-23 20:08 ` Navid Rahimi
2021-11-23 20:14 ` Jeff Law
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