From: Segher Boessenkool <segher@kernel.crashing.org>
To: Jan Beulich <jbeulich@suse.com>
Cc: Rainer Orth <ro@cebitec.uni-bielefeld.de>,
Indu Bhagat <indu.bhagat@oracle.com>,
"linux-toolchains@vger.kernel.org"
<linux-toolchains@vger.kernel.org>,
Jens Remus <jremus@linux.ibm.com>
Subject: Re: Unaligned access trade-offs for SFrame FRE layout
Date: Mon, 15 Sep 2025 04:08:29 -0500 [thread overview]
Message-ID: <aMfXjVw2ijr7u-Al@gate> (raw)
In-Reply-To: <26895e7a-5d54-4c89-aeb4-bcd094ba081d@suse.com>
On 14.09.2025 16:39, Rainer Orth wrote:
>> On 12.09.2025 19:34, Indu Bhagat via Binutils wrote:
> look for STRICT_ALIGNMENT in the GCC sources in gcc/config. While
> several are embedded targets, there's also sparc in that list.
>
> But is this setting a good reference for the purpose here.
It is not a setting usually, also not for you, it is a command-line
option. Often it is good (for performance) to only do naturally aligned
accesses. For some (sub-)archs it simply is impossible to even try to
do misaligned accesses OTOH.
> It's okay for gcc to make assumptions (assuming they're properly
> documented),
Only some implementation decisions have to be documented. And
assumptions are almost never okay. Typically we depend on the user
promising they do not do X (via a -mno-X flag, say) before we assume
they do not do X.
Segher
prev parent reply other threads:[~2025-09-15 15:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-12 17:34 Unaligned access trade-offs for SFrame FRE layout Indu Bhagat
2025-09-12 18:19 ` Segher Boessenkool
2025-09-12 19:18 ` Steven Rostedt
2025-09-13 7:56 ` Indu Bhagat
2025-09-15 16:04 ` Steven Rostedt
[not found] ` <CAEG7qUxk_cZYv3X_VM6+ZGaVFAD-7jdPd3xA92xYHUAqyzb2Xw@mail.gmail.com>
2025-09-13 8:01 ` Indu Bhagat
2025-09-14 14:14 ` Jan Beulich
2025-09-14 14:39 ` Rainer Orth
2025-09-14 15:23 ` Jan Beulich
2025-09-14 16:18 ` Rainer Orth
2025-09-14 18:10 ` Jan Beulich
2025-09-15 5:42 ` Indu Bhagat
2025-09-15 16:07 ` Steven Rostedt
2025-09-15 17:22 ` Segher Boessenkool
2025-09-16 6:05 ` Fangrui Song
2025-09-16 15:58 ` Steven Rostedt
2025-09-18 10:39 ` Jens Remus
2025-09-16 16:03 ` Indu Bhagat
2025-09-16 16:32 ` Fangrui Song
2025-09-16 16:44 ` Segher Boessenkool
2025-09-16 17:05 ` Fangrui Song
2025-09-16 17:54 ` Segher Boessenkool
2025-09-16 17:33 ` Indu Bhagat
2025-09-17 21:12 ` Steven Rostedt
2025-09-17 23:55 ` Alan Modra
2025-09-15 9:08 ` Segher Boessenkool [this message]
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