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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Jonathan Wakely <jwakely.gcc@gmail.com>,
	gcc-help <gcc-help@gcc.gnu.org>,
	 unlvsur unlvsur <unlvsur@live.com>
Subject: Re: how to get -march=native's value?
Date: Mon, 27 Sep 2021 12:13:44 -0500	[thread overview]
Message-ID: <20210927171344.GA8185@gate.crashing.org> (raw)
In-Reply-To: <20210927125528.GA3789484@cventin.lip.ens-lyon.fr>

On Mon, Sep 27, 2021 at 02:55:28PM +0200, Vincent Lefevre wrote:
> On 2021-09-17 12:53:25 -0500, Segher Boessenkool wrote:
> > For x86 -march=something is the same as -march=native, _if_ the compiler
> > knows about your CPU.

> -  -mabm                                [disabled]
> +  -mabm                                [enabled]

So -mcpu=haswell disables ABM?  Huh.

I do not know the x86 backend very well, but that looks like a bug.

> -  -maes                                [disabled]
> +  -maes                                [enabled]

Here, too.  Esp. because the documentation says it 8should* be enabled.

Maybe some features are disabled on some Haswell though?

> -  --param=l1-cache-size=               64
> -  --param=l2-cache-size=               512
> +  --param=l1-cache-size=               32
> +  --param=l2-cache-size=               15360

This I already explained.


Segher

  reply	other threads:[~2021-09-27 17:14 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-07  7:02 unlvsur unlvsur
2021-09-07  7:56 ` Jonathan Wakely
2021-09-17  2:46   ` NightStrike
2021-09-17  8:29     ` Xi Ruoyao
2021-09-17 10:26       ` Jonathan Wakely
2021-09-17 10:38         ` Jonathan Wakely
2021-09-17 17:53         ` Segher Boessenkool
2021-09-27 12:55           ` Vincent Lefevre
2021-09-27 17:13             ` Segher Boessenkool [this message]
2021-09-27 18:14               ` L A Walsh
2021-09-27 18:25                 ` Jonathan Wakely
2021-09-27 20:26                   ` Segher Boessenkool
2021-09-27 20:30                     ` NightStrike
2021-09-27 18:26                 ` Florian Weimer
2021-09-07  7:59 ` Hongtao Liu

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