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From: Junio C Hamano <junkio@cox•net>
To: Andy Parkins <andyparkins@gmail•com>
Cc: git@vger•kernel.org
Subject: Re: [PATCH] Change "refs/" references to symbolic constants
Date: Tue, 20 Feb 2007 01:04:25 -0800	[thread overview]
Message-ID: <7vlkitxkrq.fsf@assigned-by-dhcp.cox.net> (raw)
In-Reply-To: <200702200841.26578.andyparkins@gmail.com> (Andy Parkins's message of "Tue, 20 Feb 2007 08:41:24 +0000")

Andy Parkins <andyparkins@gmail•com> writes:

> As I've said before, I'm against /any/ special treatment of
> master other than as a default branch name in a newly
> initialised repository.  PATH_REFS_HEADS_MASTER is closer to
> master not being special than without so I'd be in favour of
> that.

Ok.

>> These repeated strncmp(p, X, STRLEN_X) almost makes me wonder if we
>> want to introduce:
>>
>> 	inline int prefixcmp(a, b)
>>         {
>>         	return (strncmp(a, b, strlen(b));
>>         }
>>
>> with clever preprocessor optimization to have compiler do strlen()
>> when b is a string literal.
>
> Wow; that would be clever - regardless of whether this patch
> is acceptable or not.

Actually GCC seems to be clever enough.  It appears that I do
not even have to do prefixcmp_0() below; prefixcmp_1() seems to
generate good code, with GCC 4.1.2 prerelease on my x86_64.

-- >8 --
#include <string.h>
static inline int prefixcmp_0(const char *a, const char *b)
{
	if (__builtin_constant_p(b))
		return strncmp(a, b, sizeof(b) - 1);
	else
		return strncmp(a, b, strlen(b));
}

static inline prefixcmp_1(const char *a, const char *b)
{
	return strncmp(a, b, strlen(b));
}

void foo(const char *s, const char *t, int *a, int *b, int *c, int *d)
{
	*a = prefixcmp_0(s, "abcdefg");
	*b = prefixcmp_0(s, t);
	*c = prefixcmp_1(s, "ABCDEFGH");
	*d = prefixcmp_1(s, t);
}
-- 8< --

  reply	other threads:[~2007-02-20  9:04 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-19 18:39 [PATCH] Change "refs/" references to symbolic constants Andy Parkins
2007-02-19 18:55 ` Bill Lear
2007-02-19 20:01   ` [PATCH] Replace literal STRLEN_ #defines in refs.h with compiler evaluated expressions Andy Parkins
2007-02-19 20:50   ` [PATCH] Change "refs/" references to symbolic constants Krzysztof Halasa
2007-02-19 20:56     ` Shawn O. Pearce
2007-02-19 20:07 ` Junio C Hamano
2007-02-19 20:12   ` Shawn O. Pearce
2007-02-19 22:08   ` Johannes Schindelin
2007-02-20  8:41   ` Andy Parkins
2007-02-20  9:04     ` Junio C Hamano [this message]
2007-02-20  9:42   ` Andy Parkins
2007-02-20  9:50     ` Junio C Hamano
2007-02-20 10:21       ` Andy Parkins
2007-02-20 10:30         ` Junio C Hamano
2007-02-20 10:57           ` Andy Parkins
2007-02-20 11:37             ` Johannes Schindelin
2007-02-20 12:24               ` Simon 'corecode' Schubert
2007-02-20 13:26                 ` Johannes Schindelin
2007-02-20 13:26               ` Andy Parkins
2007-02-20 15:46             ` Nicolas Pitre
2007-02-20  9:51     ` [PATCH 1/4] Add prefixcmp() Junio C Hamano
2007-02-20 10:04       ` David Kågedal
2007-02-20 10:20         ` Junio C Hamano
2007-02-20  9:53     ` [PATCH 2/4] Mechanical conversion to use prefixcmp() Junio C Hamano
2007-02-20 10:19       ` Junio C Hamano
2007-02-20 11:53       ` Johannes Schindelin
2007-02-21  6:43         ` Junio C Hamano
2007-02-21 12:41           ` Johannes Schindelin
2007-02-20  9:54     ` [PATCH 3/4] prefixcmp(): fix-up mechanical conversion Junio C Hamano
2007-02-20  9:55     ` [PATCH 4/4] prefixcmp(): fix-up leftover strncmp() Junio C Hamano
  -- strict thread matches above, loose matches on Subject: below --
2007-10-02 15:58 [PATCH 1/2] Change "refs/" references to symbolic constants Jeff King
2007-10-02 18:16 ` [PATCH] " Andy Parkins
2007-10-02 19:11   ` Jeff King
2007-10-02 19:47     ` Junio C Hamano
2007-10-02 20:48       ` Jeff King
2007-10-03  0:22         ` Junio C Hamano
2007-10-03  2:58           ` Jeff King
2007-10-03  4:05             ` Johannes Schindelin
2007-10-03  4:30               ` Jeff King
2007-10-03 11:30               ` Andreas Ericsson
2007-10-03  7:37         ` Andy Parkins
2007-10-03  7:50     ` Andy Parkins
2007-10-03 11:13       ` Andy Parkins

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