commit 1edad85b16fdda43c8ab809e2779e8bf64ab8bb2
author Heiko Carstens <heiko.carstens@de.ibm.com> Thu Mar 26 15:24:37 2009 +0100
committer Martin Schwidefsky <schwidefsky@de.ibm.com> Thu Mar 26 15:24:24 2009 +0100
tree 45e777718c8fda461c2232f2b74b8dc0a04e4ea6
parent 504665a91498f43d220b7d0942281067283a35f7

[S390] use compiler builtin versions of strlen/strcpy/strcat

Use builtin variants if gcc 4 or newer is used to compile the kernel.
Generates better code than the asm variants.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/string.h

diff --git a/arch/s390/include/asm/string.h b/arch/s390/include/asm/string.h
index adf0791..cd0241d 100644
--- a/arch/s390/include/asm/string.h
+++ b/arch/s390/include/asm/string.h
@@ -100,6 +100,7 @@
 
 static inline char *strcpy(char *dst, const char *src)
 {
+#if __GNUC__ < 4
 	register int r0 asm("0") = 0;
 	char *ret = dst;
 
@@ -109,10 +110,14 @@
 		: "+&a" (dst), "+&a" (src) : "d" (r0)
 		: "cc", "memory");
 	return ret;
+#else
+	return __builtin_strcpy(dst, src);
+#endif
 }
 
 static inline size_t strlen(const char *s)
 {
+#if __GNUC__ < 4
 	register unsigned long r0 asm("0") = 0;
 	const char *tmp = s;
 
@@ -121,6 +126,9 @@
 		"	jo	0b"
 		: "+d" (r0), "+a" (tmp) :  : "cc");
 	return r0 - (unsigned long) s;
+#else
+	return __builtin_strlen(s);
+#endif
 }
 
 static inline size_t strnlen(const char * s, size_t n)

arch/s390/lib/string.c

diff --git a/arch/s390/lib/string.c b/arch/s390/lib/string.c
index ae5cf5d..4143b7c 100644
--- a/arch/s390/lib/string.c
+++ b/arch/s390/lib/string.c
@@ -44,7 +44,11 @@
  */
 size_t strlen(const char *s)
 {
+#if __GNUC__ < 4
 	return __strend(s) - s;
+#else
+	return __builtin_strlen(s);
+#endif
 }
 EXPORT_SYMBOL(strlen);
 
@@ -70,6 +74,7 @@
  */
 char *strcpy(char *dest, const char *src)
 {
+#if __GNUC__ < 4
 	register int r0 asm("0") = 0;
 	char *ret = dest;
 
@@ -78,6 +83,9 @@
 		      : "+&a" (dest), "+&a" (src) : "d" (r0)
 		      : "cc", "memory" );
 	return ret;
+#else
+	return __builtin_strcpy(dest, src);
+#endif
 }
 EXPORT_SYMBOL(strcpy);