From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
"Jan Beulich" <JBeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>,
"Julien Grall" <julien@xen.org>,
"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
"Bertrand Marquis" <bertrand.marquis@arm.com>,
"Michal Orzel" <michal.orzel@amd.com>
Subject: Re: [PATCH] xen: Use asm inline when available for alternatives
Date: Tue, 22 Apr 2025 20:53:21 +0100 [thread overview]
Message-ID: <0570b0ed-607c-49fa-b82e-29ffac60f873@citrix.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2504221244360.785180@ubuntu-linux-20-04-desktop>
On 22/04/2025 8:46 pm, Stefano Stabellini wrote:
> On Tue, 22 Apr 2025, Andrew Cooper wrote:
>> Compilers estimate the size of an asm() block for inlining purposes.
>>
>> Constructs such as ALTERNATIVE appear large due to the metadata, depsite often
>> only being a handful of instructions. asm inline() overrides the estimation
>> to identify the block as being small.
>>
>> This has a substantial impact on inlining decisions, expected to be for the
>> better given that the compiler has a more accurate picture to work with.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Hi Andrew,
>
> If we are going to use asm_inline, please add a note to
> docs/misra/C-language-toolchain.rst where we keep record of all the
> language extensions we use.
It's just asm(), and that's already discussed.
I'm not sure what else you think is warranted.
~Andrew
next prev parent reply other threads:[~2025-04-22 19:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-22 11:39 [PATCH] xen: Use asm inline when available for alternatives Andrew Cooper
2025-04-22 12:33 ` Frediano Ziglio
2025-04-22 12:52 ` Jan Beulich
2025-05-15 16:26 ` Andrew Cooper
2025-04-22 19:46 ` Stefano Stabellini
2025-04-22 19:53 ` Andrew Cooper [this message]
2025-04-22 19:58 ` Stefano Stabellini
2025-04-22 20:01 ` Nicola Vetrini
2025-04-22 20:02 ` Stefano Stabellini
2025-04-22 20:08 ` Nicola Vetrini
2025-04-22 20:12 ` Stefano Stabellini
2025-04-22 20:03 ` Andrew Cooper
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