From: Richard Biener <richard.guenther@gmail.com>
To: Abe <abe_skolnik@yahoo.com>
Cc: Alan Lawrence <alan.lawrence@arm.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,
Sebastian Pop <sebpop@gmail.com>
Subject: Re: Another benefit of the new if converter: better performance for half hammocks when running the generated code on a modern high-speed CPU with write-back caching, relative to the code produced by the old if converter given the same source code
Date: Fri, 31 Jul 2015 10:24:00 -0000 [thread overview]
Message-ID: <CAFiYyc1L2DYfHYbXuUfGh8+72Hf6=nH-spf2hi5RUh_ptekdhA@mail.gmail.com> (raw)
In-Reply-To: <55B8FE61.7060008@yahoo.com>
On Wed, Jul 29, 2015 at 6:25 PM, Abe <abe_skolnik@yahoo.com> wrote:
>> Well. We don't generally introduce regressions with changes.
>
>
> Understood. Regressions are bad, of course. TTBOMK the
> regressions in question are temporary. Once they are gone,
> I think we can then look at whether or not we still
> need to keep the old if converter in trunk. Ideally,
> it eventually becomes redundant and unneeded.
>
>
>> (well, the patch still needs review -
>
>> I hope to get to that this week).
>
> After I`ve done the SPEC-based analysis, my next planned steps
> on this work are to disable the code that [in my WIP] currently
> causes conversion to be enabled by default when autovectorization
> is enabled, then to re-integrate the old converter and implement
> the switches that will give GCC users access to the modes I described
> in a recent email from me. You might prefer to delay your code review
> until I have that all done and a new version of the patch submitted.
I'm not sure we want two if-converters. What we do want is avoid
using a scratch-pad if it is safe to do (for loads and stores)
and if the user tells us he is fine with store data races (for stores).
Does the "new" if-converter get rid of the analysis code that
determined "safe"? If so you should re-instantiate that.
Richard.
> Regards,
>
> Abe
next prev parent reply other threads:[~2015-07-31 10:17 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-17 20:33 Abe
2015-07-28 10:27 ` Richard Biener
2015-07-28 18:18 ` Abe
2015-07-29 9:51 ` Richard Biener
2015-07-29 17:19 ` Abe
2015-07-31 10:24 ` Richard Biener [this message]
2015-07-31 18:29 ` Abe
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