From: Pedro Alves <pedro@palves.net>
To: Eli Zaretskii <eliz@gnu.org>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH 1/3] struct packed: Use gcc_struct on Windows
Date: Thu, 21 Jul 2022 18:05:55 +0100 [thread overview]
Message-ID: <a5f58990-3586-ebd1-2998-f4aec7b935db@palves.net> (raw)
In-Reply-To: <83h73amp19.fsf@gnu.org>
On 2022-07-21 5:03 p.m., Eli Zaretskii wrote:
>> From: Pedro Alves <pedro@palves.net>
>> Date: Thu, 21 Jul 2022 16:21:30 +0100
>>
>> The issue is that mingw gcc defaults to "-mms-bitfields", which
>> affects how bitfields are laid out. We can however tell GCC that we
>> want the regular GCC layout instead using attribute gcc_struct.
>
> Is that a good idea? It means the code emitted by GCC for this source
> file will be incompatible with any other library compiled with MinGW
> that GDB uses. So we are risking ABI incompatibilities here. Right?
>
No. The attribute only changes the layout of that particular structure.
> Can you tell why we must have the regular GCC layout of bitfields
> here?
Because without it the struct won't really be packed.
next prev parent reply other threads:[~2022-07-21 17:06 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-21 15:21 [PATCH 0/3] struct packed and Windows ports (PR build/29373) Pedro Alves
2022-07-21 15:21 ` [PATCH 1/3] struct packed: Use gcc_struct on Windows Pedro Alves
2022-07-21 16:03 ` Eli Zaretskii
2022-07-21 17:05 ` Pedro Alves [this message]
2022-07-21 17:40 ` Eli Zaretskii
2022-07-21 18:15 ` Pedro Alves
2022-07-21 18:23 ` Eli Zaretskii
2022-07-21 18:30 ` Pedro Alves
2022-07-21 18:45 ` Eli Zaretskii
2022-07-21 18:57 ` Pedro Alves
2022-07-21 18:18 ` Pedro Alves
2022-07-21 18:28 ` Eli Zaretskii
2022-07-21 18:38 ` Pedro Alves
2022-07-21 15:21 ` [PATCH 2/3] struct packed: Unit tests and more operators Pedro Alves
2022-07-21 15:21 ` [PATCH 3/3] struct packed: Add fallback byte array implementation Pedro Alves
2022-07-25 14:58 ` [PATCH 0/3] struct packed and Windows ports (PR build/29373) Tom Tromey
2022-07-25 15:18 ` Pedro Alves
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