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Date: Sun, 24 May 2015 19:10:36 +0200
From: =?utf-8?B?T25kxZllaiBCw61sa2E=?= <neleai@seznam.cz>
To: libc-alpha@sourceware.org
Cc: Wilco Dijkstra <wdijkstr@arm.com>
Subject: Re: [PATCH 4/* v2] Optimize strchrnul more
Message-ID: <20150524171036.GA20947@domone>
References: <20150524150715.GA31589@domone> <20150524163214.GA28053@domone>
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In-Reply-To: <20150524163214.GA28053@domone>
User-Agent: Mutt/1.5.20 (2009-06-14)

On Sun, May 24, 2015 at 06:32:14PM +0200, Ondřej Bílka wrote:
> Hi,
> this is nontrivial optimization of string inlines.
> First it decreases icache pressure as you don't need strchr.
> 

Just realized that optimization there is silly way to find terminating
zero. On x64 rawmemchr is around 50% slower than strlen so add rawmemchr
special case that does just that.
 
 	* string/bits/string2.h (strchrnul, rawmemchr): Add inline
 	  (strchr): Optimize.

diff --git a/string/bits/string2.h b/string/bits/string2.h
index 2fe67b3..8f1eb04 100644
--- a/string/bits/string2.h
+++ b/string/bits/string2.h
@@ -108,18 +108,39 @@ __STRING2_COPY_TYPE (8);
 #endif
 
 
-/* Return pointer to C in S.  */
-#ifndef _HAVE_STRING_ARCH_strchr
+#ifndef _HAVE_STRING_ARCH_rawmemchr
 extern void *__rawmemchr (const void *__s, int __c);
 # if __GNUC_PREREQ (3, 2)
-#  define strchr(s, c) \
+#  define __rawmemchr(s, c) \
+  (__extension__ (__builtin_constant_p (c) && !__builtin_constant_p (s)	      \
+		  && (c) == '\0'					      \
+		  ? s + strlen (s) 					      \
+		  : __rawmemchr (s, c)))
+# endif
+#endif
+
+
+
+#ifndef _HAVE_STRING_ARCH_strchrnul
+# if __GNUC_PREREQ (3, 2)
+#  define strchrnul(s, c) \
   (__extension__ (__builtin_constant_p (c) && !__builtin_constant_p (s)	      \
 		  && (c) == '\0'					      \
 		  ? (char *) __rawmemchr (s, c)				      \
-		  : __builtin_strchr (s, c)))
+		  : strchrnul (s, c)))
 # endif
 #endif
 
+/* Return pointer to C in S.  */
+#ifndef _HAVE_STRING_ARCH_strchr
+# if __GNUC_PREREQ (3, 2)
+#  define strchr(s, c) \
+  (__extension__ ({ char *__r = strchrnul (s, c);			      \
+		       *__r == c ? __r : NULL; }))
+# endif
+#endif
+
+
 /* Copy SRC to DEST, returning pointer to final NUL byte.  */
 #ifdef __USE_GNU
 # if !defined _HAVE_STRING_ARCH_stpcpy || defined _FORCE_INLINES