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Remove fls(), use pg_leftmost_one_pos32() instead.

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Commit 4f658dc8 provided the traditional BSD fls() function in
src/port/fls.c so it could be used in several places.  Later we added a
bunch of similar facilities in pg_bitutils.h, based on compiler
builtins that map to hardware instructions.  It's a bit confusing to
have both 1-based and 0-based variants of this operation in use in
different parts of the tree, and neither is blessed by a standard.
Let's drop fls.c and the configure probe, and reuse the newer code.

Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CA%2BhUKG%2B7dSX1XF8yFGmYk-%3D48dbjH2kmzZj16XvhbrWP-9BzRg%40mail.gmail.com
This commit is contained in:
Thomas Munro
2022-07-22 09:41:12 +12:00
parent 3225399021
commit 4f1f5a7f85
11 changed files with 19 additions and 92 deletions
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64
src/port/fls.c
View File

@@ -1,64 +0,0 @@
/*-------------------------------------------------------------------------
*
* fls.c
* finds the last (most significant) bit that is set
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/port/fls.c
*
* This file was taken from FreeBSD to provide an implementation of fls()
* for platforms that lack it. Note that the operating system's version may
* be substantially more efficient than ours, since some platforms have an
* assembly instruction that does exactly this.
*
* The FreeBSD copyright terms follow.
*/
/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "c.h"
/*
* Find Last Set bit
*/
int
fls(int mask)
{
int bit;
if (mask == 0)
return (0);
for (bit = 1; mask != 1; bit++)
mask = (unsigned int) mask >> 1;
return (bit);
}