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string fixes for gcc 3.4

PATCH In review Andi Kleen 3 participants 3 messages Jan 14, 2004

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Andi Kleen

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#0 lore raw

PATCH 1/1 string fixes for gcc 3.4

gcc 3.4 optimizes sprintf(foo,"%s",string) into strcpy. Unfortunately that isn't seen by the inliner and linux/i386 has no out-of-line strcpy so you end up with a linker error.

This patch adds out of line copies for most string functions to avoid this. Actually it doesn't export them to modules yet, that would be the next step.

BTW In my opinion we shouldn't use inline string functions at all. The __builtin_str* in modern gcc are better (I used them very successfully on x86-64) and for the bigger functions like strrchr,strtok et.al. it just doesn't make any sense to inline them or even code them in assembler.

Also fix the bcopy prototype gcc was complaining about.

-Andi

lib/string.c renamed from lib/string.c-o +6 -3
diff -u linux-34/lib/string.c-o linux-34/lib/string.c
@@ -18,6 +18,8 @@
  *                    Matthew Hawkins <[email protected]>
  * -  Kissed strtok() goodbye
  */
+
+#define IN_STRING_C 1
  
 #include <linux/types.h>
 #include <linux/string.h>

@@ -437,12 +439,13 @@
  * You should not use this function to access IO space, use memcpy_toio()
  * or memcpy_fromio() instead.
  */
-void bcopy(const char * src, char * dest, int count)
+void bcopy(const void * srcp, void * destp, size_t count)
 {
-	char *tmp = dest;
+	const char *src = srcp;
+	char *dest = destp;
 
 	while (count--)
-		*tmp++ = *src++;
+		*dest++ = *src++;
 }
 #endif
include/asm-i386/string.h renamed from include/asm-i386/string.h-o +6 -8
diff -u linux-34/include/asm-i386/string.h-o linux-34/include/asm-i386/string.h
@@ -23,7 +23,10 @@
  *		consider these trivial functions to be PD.
  */
 
-#define __HAVE_ARCH_STRCPY
+/* AK: in fact I bet it would be better to move this stuff all out of line.
+ */
+#if !defined(IN_STRING_C)
+
 static inline char * strcpy(char * dest,const char *src)
 {
 int d0, d1, d2;

@@ -37,7 +40,6 @@
 return dest;
 }
 
-#define __HAVE_ARCH_STRNCPY
 static inline char * strncpy(char * dest,const char *src,size_t count)
 {
 int d0, d1, d2, d3;

@@ -56,7 +58,6 @@
 return dest;
 }
 
-#define __HAVE_ARCH_STRCAT
 static inline char * strcat(char * dest,const char * src)
 {
 int d0, d1, d2, d3;

@@ -73,7 +74,6 @@
 return dest;
 }
 
-#define __HAVE_ARCH_STRNCAT
 static inline char * strncat(char * dest,const char * src,size_t count)
 {
 int d0, d1, d2, d3;

@@ -96,7 +96,6 @@
 return dest;
 }
 
-#define __HAVE_ARCH_STRCMP
 static inline int strcmp(const char * cs,const char * ct)
 {
 int d0, d1;

@@ -117,7 +116,6 @@
 return __res;
 }
 
-#define __HAVE_ARCH_STRNCMP
 static inline int strncmp(const char * cs,const char * ct,size_t count)
 {
 register int __res;

@@ -140,7 +138,6 @@
 return __res;
 }
 
-#define __HAVE_ARCH_STRCHR
 static inline char * strchr(const char * s, int c)
 {
 int d0;

@@ -159,7 +156,6 @@
 return __res;
 }
 
-#define __HAVE_ARCH_STRRCHR
 static inline char * strrchr(const char * s, int c)
 {
 int d0, d1;

@@ -176,6 +172,8 @@
 return __res;
 }
 
+#endif
+
 #define __HAVE_ARCH_STRLEN
 static inline size_t strlen(const char * s)
 {
#1 lore raw
Quoted 4 lines · Andi Kleen

gcc 3.4 optimizes sprintf(foo,"%s",string) into strcpy. Unfortunately that isn't seen by the inliner and linux/i386 has no out-of-line strcpy so you end up with a linker error.

The other alternative is -ffreestanding. Kernel in its current shape certainly is not a hosted environment.
But I agree GCC does a better job with string/memory functions than kernel with its inlines.

Jakub

#2 lore raw
Quoted 8 lines · Jakub Jelinek
Quoted 4 lines · Andi Kleen

gcc 3.4 optimizes sprintf(foo,"%s",string) into strcpy. Unfortunately that isn't seen by the inliner and linux/i386 has no out-of-line strcpy so you end up with a linker error.

The other alternative is -ffreestanding. Kernel in its current shape certainly is not a hosted environment.

Good point.

Quoted 2 lines

But I agree GCC does a better job with string/memory functions than kernel with its inlines.

If anybody wants to try it:
cp include/asm-x86_64/string.h include/asm-i386/string.h should do approximately the right thing.

-Andi