From: Jeff Law <jeffreyalaw@gmail.com>
To: Segher Boessenkool <segher@kernel.crashing.org>,
Richard Biener <rguenther@suse.de>
Cc: gcc-patches@gcc.gnu.org, Jakub Jelinek <jakub@redhat.com>
Subject: Re: [PATCH] rtl-optimization/101523 - avoid re-combine after noop 2->2 combination
Date: Fri, 5 Apr 2024 15:46:30 -0600 [thread overview]
Message-ID: <6c387fd6-bf1d-45b5-b4bb-96a947217a5c@gmail.com> (raw)
In-Reply-To: <20240405212754.GL19790@gate.crashing.org>
On 4/5/24 3:27 PM, Segher Boessenkool wrote:
> Hi!
>
> On Wed, Apr 03, 2024 at 01:07:41PM +0200, Richard Biener wrote:
>> The following avoids re-walking and re-combining the instructions
>> between i2 and i3 when the pattern of i2 doesn't change.
>>
>> Bootstrap and regtest running ontop of a reversal of
>> r14-9692-g839bc42772ba7a.
>
> Please include that in the patch (or series, preferably).
>
>> It brings down memory use frmo 9GB to 400MB and compile-time from
>> 80s to 3.5s. r14-9692-g839bc42772ba7a does better in both metrics
>> but has shown code generation regressions across acrchitectures.
>>
>> OK to revert r14-9692-g839bc42772ba7a?
>
> No.
>
> The patch solved a very real problem. How does your replacement handle
> that? You don't say. It looks like it only battles symptoms a bit,
> instead :-(
But that patch very clearly created new problems in the process. I
would argue that it was a step backwards given that we're in stage4.
Jeff
next prev parent reply other threads:[~2024-04-05 21:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <202404031107.433B7hCA019240@gate.crashing.org>
2024-04-05 21:27 ` Segher Boessenkool
2024-04-05 21:46 ` Jeff Law [this message]
2024-04-05 21:50 ` Jakub Jelinek
2024-04-06 12:50 ` Richard Biener
2024-04-08 12:18 ` Richard Sandiford
2024-04-03 11:07 Richard Biener
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