svn commit: r368027 - stable/12/lib/libc/string

[Ed Maste]

Author: emaste
Date: Wed Nov 25 18:36:38 2020
New Revision: 368027
URL: https://svnweb.freebsd.org/changeset/base/368027

Log:
  MFC r351700: libc: Use musl's optimized memchr
  
  Parentheses added to HASZERO macro to avoid a GCC warning.
  
  Sponsored by:	The FreeBSD Foundation

Modified:
  stable/12/lib/libc/string/memchr.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/lib/libc/string/memchr.c
==============================================================================
--- stable/12/lib/libc/string/memchr.c	Wed Nov 25 18:09:01 2020	(r368026)
+++ stable/12/lib/libc/string/memchr.c	Wed Nov 25 18:36:38 2020	(r368027)
@@ -1,55 +1,54 @@
 /*-
- * SPDX-License-Identifier: BSD-3-Clause
+ * SPDX-License-Identifier: MIT
  *
- * Copyright (c) 1990, 1993
- *	The Regents of the University of California.  All rights reserved.
+ * Copyright (c) 2005-2014 Rich Felker, et al.
  *
- * This code is derived from software contributed to Berkeley by
- * Chris Torek.
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
  *
- * 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.
- * 3. 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.
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
  *
- * 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.
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
-
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)memchr.c	8.1 (Berkeley) 6/4/93";
-#endif /* LIBC_SCCS and not lint */
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <string.h>
+#include <stdint.h>
+#include <limits.h>
 
-void *
-memchr(const void *s, int c, size_t n)
-{
-	if (n != 0) {
-		const unsigned char *p = s;
+#define SS (sizeof(size_t))
+#define ALIGN (sizeof(size_t)-1)
+#define ONES ((size_t)-1/UCHAR_MAX)
+#define HIGHS (ONES * (UCHAR_MAX/2+1))
+#define HASZERO(x) (((x)-ONES) & ~(x) & HIGHS)
 
-		do {
-			if (*p++ == (unsigned char)c)
-				return ((void *)(p - 1));
-		} while (--n != 0);
+void *memchr(const void *src, int c, size_t n)
+{
+	const unsigned char *s = src;
+	c = (unsigned char)c;
+#ifdef __GNUC__
+	for (; ((uintptr_t)s & ALIGN) && n && *s != c; s++, n--);
+	if (n && *s != c) {
+		typedef size_t __attribute__((__may_alias__)) word;
+		const word *w;
+		size_t k = ONES * c;
+		for (w = (const void *)s; n>=SS && !HASZERO(*w^k); w++, n-=SS);
+		s = (const void *)w;
 	}
-	return (NULL);
+#endif
+	for (; n && *s != c; s++, n--);
+	return n ? (void *)s : 0;
 }