From: Christer Solskogen <christer.solskogen@gmail.com>
To: gcc-help@gcc.gnu.org
Subject: Re: aarch64 feature modifiers
Date: Mon, 21 Feb 2022 12:51:06 +0100 [thread overview]
Message-ID: <suvubc$34o$1@ciao.gmane.io> (raw)
In-Reply-To: <mpto830jvu7.fsf@arm.com>
On 21.02.2022 12:35, Richard Sandiford via Gcc-help wrote:
> Christer Solskogen via Gcc-help <gcc-help@gcc.gnu.org> writes:
>> On https://gcc.gnu.org/onlinedocs/gcc/AArch64-Options.html there's a
>> list of feature modifiers to -march and -mcpu. Is there a way to check
>> or detect what features are available on a particular CPU?
>
> If you want to compile for a specific CPU then it's better to use
> -mcpu=<that-cpu> with no feature modifiers, and leave out -march.
> GCC will then make full use of the available features.
> E.g. -mcpu=neoverse-n1 (on its own) will enable all features
> available on Neoverse N1 and optimise code for Neoverse N1.
>
> If you're just curious which features a given CPU implements,
> you can find that out by compiling a dummy file with -mcpu. E.g.:
>
> echo | gcc -mcpu=neoverse-n1 -xc - -o - -S | grep '\.arch'
>
> will print out:
>
> .arch armv8.2-a+crc+fp16+rcpc+dotprod+profile
>
>
I see. Thank you.
Does that mean that the cortex-a72 doesn't really support the +crypto or
+simd? Or does that depend on what is built?
--
chs
next prev parent reply other threads:[~2022-02-21 11:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-18 10:58 Christer Solskogen
2022-02-21 11:35 ` Richard Sandiford
2022-02-21 11:51 ` Christer Solskogen [this message]
2022-02-21 12:29 ` Richard Sandiford
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