git.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>, "Jeff King" <peff@peff.net>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: [PATCH 2/5] *.c *_init(): define in terms of corresponding *_INIT macro
Date: Thu,  1 Jul 2021 12:51:26 +0200	[thread overview]
Message-ID: <patch-2.5-955dbd1693d-20210701T104855Z-avarab@gmail.com> (raw)
In-Reply-To: <cover-0.5-00000000000-20210701T104855Z-avarab@gmail.com>

Change the common patter in the codebase of duplicating the
initialization logic between an *_INIT macro and a
corresponding *_init() function to use the macro as the canonical
source of truth.

Now we no longer need to keep the function up-to-date with the macro
version. This implements a suggestion by Jeff King who found that
under -O2 [1] modern compilers will init new version in place without
the extra copy[1]. The performance of a single *_init() won't matter
in most cases, but even if it does we're going to be producing
efficient machine code to perform these operations.

1. https://lore.kernel.org/git/YNyrDxUO1PlGJvCn@coredump.intra.peff.net/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 credential.c  | 4 ++--
 json-writer.c | 6 ++----
 run-command.c | 5 ++---
 strbuf.c      | 4 ++--
 strmap.c      | 3 ++-
 strvec.c      | 5 ++---
 6 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/credential.c b/credential.c
index e5202fbef26..3c05c7c6691 100644
--- a/credential.c
+++ b/credential.c
@@ -10,8 +10,8 @@
 
 void credential_init(struct credential *c)
 {
-	memset(c, 0, sizeof(*c));
-	c->helpers.strdup_strings = 1;
+	struct credential blank = CREDENTIAL_INIT;
+	memcpy(c, &blank, sizeof(*c));
 }
 
 void credential_clear(struct credential *c)
diff --git a/json-writer.c b/json-writer.c
index aadb9dbddc3..f1cfd8fa8c6 100644
--- a/json-writer.c
+++ b/json-writer.c
@@ -3,10 +3,8 @@
 
 void jw_init(struct json_writer *jw)
 {
-	strbuf_init(&jw->json, 0);
-	strbuf_init(&jw->open_stack, 0);
-	jw->need_comma = 0;
-	jw->pretty = 0;
+	struct json_writer blank = JSON_WRITER_INIT;
+	memcpy(jw, &blank, sizeof(*jw));;
 }
 
 void jw_release(struct json_writer *jw)
diff --git a/run-command.c b/run-command.c
index be6bc128cd9..8750df16d89 100644
--- a/run-command.c
+++ b/run-command.c
@@ -11,9 +11,8 @@
 
 void child_process_init(struct child_process *child)
 {
-	memset(child, 0, sizeof(*child));
-	strvec_init(&child->args);
-	strvec_init(&child->env_array);
+	struct child_process blank = CHILD_PROCESS_INIT;
+	memcpy(child, &blank, sizeof(*child));
 }
 
 void child_process_clear(struct child_process *child)
diff --git a/strbuf.c b/strbuf.c
index 4df30b45494..c8a5789694c 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -52,8 +52,8 @@ char strbuf_slopbuf[1];
 
 void strbuf_init(struct strbuf *sb, size_t hint)
 {
-	sb->alloc = sb->len = 0;
-	sb->buf = strbuf_slopbuf;
+	struct strbuf blank = STRBUF_INIT;
+	memcpy(sb, &blank, sizeof(*sb));
 	if (hint)
 		strbuf_grow(sb, hint);
 }
diff --git a/strmap.c b/strmap.c
index 4fb9f6100ec..ee486357082 100644
--- a/strmap.c
+++ b/strmap.c
@@ -25,7 +25,8 @@ static struct strmap_entry *find_strmap_entry(struct strmap *map,
 
 void strmap_init(struct strmap *map)
 {
-	strmap_init_with_options(map, NULL, 1);
+	struct strmap blank = STRMAP_INIT;
+	memcpy(map, &blank, sizeof(*map));
 }
 
 void strmap_init_with_options(struct strmap *map,
diff --git a/strvec.c b/strvec.c
index 21dce0a7a4d..61a76ce6cb9 100644
--- a/strvec.c
+++ b/strvec.c
@@ -6,9 +6,8 @@ const char *empty_strvec[] = { NULL };
 
 void strvec_init(struct strvec *array)
 {
-	array->v = empty_strvec;
-	array->nr = 0;
-	array->alloc = 0;
+	struct strvec blank = STRVEC_INIT;
+	memcpy(array, &blank, sizeof(*array));
 }
 
 static void strvec_push_nodup(struct strvec *array, const char *value)
-- 
2.32.0.623.ge833f40cd87


  parent reply	other threads:[~2021-07-01 10:51 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-01 10:51 [PATCH 0/5] *.[ch]: don't duplicate *_init() and *_INIT logic Ævar Arnfjörð Bjarmason
2021-07-01 10:51 ` [PATCH 1/5] *.h: move some *_INIT to designated initializers Ævar Arnfjörð Bjarmason
2021-07-01 15:00   ` Martin Ågren
2021-07-01 15:56     ` Junio C Hamano
2021-07-01 16:08     ` Ævar Arnfjörð Bjarmason
2021-07-01 10:51 ` Ævar Arnfjörð Bjarmason [this message]
2021-07-01 10:51 ` [PATCH 3/5] dir.[ch]: replace dir_init() with DIR_INIT Ævar Arnfjörð Bjarmason
2021-07-01 10:51 ` [PATCH 4/5] string-list.[ch]: add a string_list_init_{nodup,dup}() Ævar Arnfjörð Bjarmason
2021-07-01 10:51 ` [PATCH 5/5] string-list.h users: change to use *_{nodup,dup}() Ævar Arnfjörð Bjarmason
2021-07-01 16:13 ` [PATCH 0/5] *.[ch]: don't duplicate *_init() and *_INIT logic Jeff King

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=patch-2.5-955dbd1693d-20210701T104855Z-avarab@gmail.com \
    --to=avarab@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=peff@peff.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).