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From: Jeff King <peff@peff.net>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Andrei Rybak <rybak.a.v@gmail.com>
Subject: Re: [PATCH v3 0/3]
Date: Wed, 30 Jun 2021 13:45:11 -0400	[thread overview]
Message-ID: <YNytp0JAIaQih0Y4@coredump.intra.peff.net> (raw)
In-Reply-To: <YNyrDxUO1PlGJvCn@coredump.intra.peff.net>

On Wed, Jun 30, 2021 at 01:34:07PM -0400, Jeff King wrote:

> As an aside, having to have a separate bundle_header_init() and
> BUNDLE_HEADER_INIT is annoying (because they both must be kept up to
> date with each other), but quite common in our code base. I wonder if
> writing:
> 
>   void bundle_header_init(struct bundle_header *header)
>   {
> 	struct bundle_header blank = BUNDLE_HEADER_INIT;
> 	memcpy(header, &blank, sizeof(*header));
>   }
> 
> would let a smart enough compiler just init "header" in place without
> the extra copy (the performance of a single bundle_header almost
> certainly doesn't matter, but it might for other types).
> 
> Just musing. ;)

For my own curiosity, the answer is yes: https://godbolt.org/z/s54dc6ss9

With "gcc -O2" the memcpy goes away and we init "header" directly.

If we want to start using this technique widely, I don't think it should
be part of your series, though. This probably applies to quite a few
data structures, so it would make more sense to have a series which
converts several.

-Peff

  reply	other threads:[~2021-06-30 17:45 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-17 11:21 [PATCH 0/3] bundle.c: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-17 11:21 ` [PATCH 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-06-17 11:21 ` [PATCH 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-06-17 11:21 ` [PATCH 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-19  2:12   ` Andrei Rybak
2021-06-21 15:16 ` [PATCH v2 0/3] bundle.c: " Ævar Arnfjörð Bjarmason
2021-06-21 15:16   ` [PATCH v2 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-06-24 16:54     ` Jeff King
2021-06-24 19:28       ` Ævar Arnfjörð Bjarmason
2021-06-21 15:16   ` [PATCH v2 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-06-21 15:16   ` [PATCH v2 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-24 17:11     ` Jeff King
2021-06-24 19:31       ` Ævar Arnfjörð Bjarmason
2021-06-29  1:02       ` Junio C Hamano
2021-06-24 17:14   ` [PATCH v2 0/3] bundle.c: " Jeff King
2021-06-30 14:06   ` [PATCH v3 0/3] Ævar Arnfjörð Bjarmason
2021-06-30 14:06     ` [PATCH v3 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-06-30 17:26       ` Jeff King
2021-06-30 18:00         ` Ævar Arnfjörð Bjarmason
2021-07-01 15:41           ` Jeff King
2021-06-30 14:06     ` [PATCH v3 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-06-30 14:06     ` [PATCH v3 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-06-30 21:18       ` Junio C Hamano
2021-06-30 17:34     ` [PATCH v3 0/3] Jeff King
2021-06-30 17:45       ` Jeff King [this message]
2021-06-30 18:00         ` Ævar Arnfjörð Bjarmason
2021-07-01 10:53           ` Ævar Arnfjörð Bjarmason
2021-07-02  9:57     ` [PATCH v4 0/3] bundle.c: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-07-02  9:57       ` [PATCH v4 1/3] bundle cmd: stop leaking memory from parse_options_cmd_bundle() Ævar Arnfjörð Bjarmason
2021-07-02  9:57       ` [PATCH v4 2/3] bundle.c: use a temporary variable for OIDs and names Ævar Arnfjörð Bjarmason
2021-07-02  9:57       ` [PATCH v4 3/3] bundle: remove "ref_list" in favor of string-list.c API Ævar Arnfjörð Bjarmason
2021-07-03 10:52       ` [PATCH v4 0/3] bundle.c: " Jeff King
2021-07-03 11:28         ` Ævar Arnfjörð Bjarmason
  -- strict thread matches above, loose matches on Subject: below --
2018-11-11 23:58 [PATCH v2 0/2] refactoring branch colorization to ref-filter nbelakovski
2018-12-16 21:57 ` [PATCH v3 0/3] nbelakovski
2018-12-18 17:25   ` Jeff King
2012-02-16 22:14 [PATCH v2 1/3] Move the user-facing test library to test-lib-functions.sh Junio C Hamano
2012-02-17 10:25 ` [PATCH v3 0/3] Thomas Rast
2012-02-17 17:03   ` Junio C Hamano
2012-02-17 23:28     ` Junio C Hamano
2012-02-18  0:51       ` Jeff King
2012-02-18  7:27         ` Junio C Hamano
2012-02-18  8:52           ` Jeff King

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