From: Rich Felker <dalias@aerifal.cx>
Date: Thu, 27 Sep 2012 20:56:33 +0000 (-0400)
Subject: slightly cleaner strlen, also seems to compile to better code
X-Git-Tag: v0.9.7~84
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=3f9ff1514e49b06c20a61af9ae9e52bd53b48d9a;p=oweals%2Fmusl.git

slightly cleaner strlen, also seems to compile to better code

testing with gcc 4.6.3 on x86, -Os, the old version does a duplicate
null byte check after the first loop. this is purely the compiler
being stupid, but the old code was also stupid and unintuitive in how
it expressed the check.
---

diff --git a/src/string/strlen.c b/src/string/strlen.c
index 936fb5cf..d6f8631d 100644
--- a/src/string/strlen.c
+++ b/src/string/strlen.c
@@ -3,7 +3,7 @@
 #include <stdint.h>
 #include <limits.h>
 
-#define ALIGN (sizeof(size_t)-1)
+#define ALIGN (sizeof(size_t))
 #define ONES ((size_t)-1/UCHAR_MAX)
 #define HIGHS (ONES * (UCHAR_MAX/2+1))
 #define HASZERO(x) ((x)-ONES & ~(x) & HIGHS)
@@ -12,10 +12,8 @@ size_t strlen(const char *s)
 {
 	const char *a = s;
 	const size_t *w;
-	for (; ((uintptr_t)s & ALIGN) && *s; s++);
-	if (*s) {
-		for (w = (const void *)s; !HASZERO(*w); w++);
-		for (s = (const void *)w; *s; s++);
-	}
+	for (; (uintptr_t)s % ALIGN; s++) if (!*s) return s-a;
+	for (w = (const void *)s; !HASZERO(*w); w++);
+	for (s = (const void *)w; *s; s++);
 	return s-a;
 }