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ff5fdafc9e
The __memzero assembly code is almost identical to memset's except for two orr instructions. The runtime performance of __memset(p, n) and memset(p, 0, n) is accordingly almost identical. However, the memset() macro used to guard against a zero length and to call __memzero at compile time when the fill value is a constant zero interferes with compiler optimizations. Arnd found tha the test against a zero length brings up some new warnings with gcc v8: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82103 And successively rremoving the test against a zero length and the call to __memzero optimization produces the following kernel sizes for defconfig with gcc 6: text data bss dec hex filename 12248142 6278960 413588 18940690 1210312 vmlinux.orig 12244474 6278960 413588 18937022 120f4be vmlinux.no_zero_test 12239160 6278960 413588 18931708 120dffc vmlinux.no_memzero So it is probably not worth keeping __memzero around given that the compiler can do a better job at inlining trivial memset(p,0,n) on its own. And the memset code already handles a zero length just fine. Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Nicolas Pitre <nico@linaro.org> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
132 lines
2 KiB
C
132 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* arch/arm/boot/compressed/string.c
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*
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* Small subset of simple string routines
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*/
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#include <linux/string.h>
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void *memcpy(void *__dest, __const void *__src, size_t __n)
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{
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int i = 0;
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unsigned char *d = (unsigned char *)__dest, *s = (unsigned char *)__src;
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for (i = __n >> 3; i > 0; i--) {
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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}
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if (__n & 1 << 2) {
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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}
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if (__n & 1 << 1) {
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*d++ = *s++;
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*d++ = *s++;
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}
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if (__n & 1)
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*d++ = *s++;
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return __dest;
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}
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void *memmove(void *__dest, __const void *__src, size_t count)
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{
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unsigned char *d = __dest;
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const unsigned char *s = __src;
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if (__dest == __src)
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return __dest;
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if (__dest < __src)
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return memcpy(__dest, __src, count);
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while (count--)
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d[count] = s[count];
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return __dest;
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}
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size_t strlen(const char *s)
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{
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const char *sc = s;
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while (*sc != '\0')
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sc++;
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return sc - s;
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}
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size_t strnlen(const char *s, size_t count)
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{
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const char *sc;
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for (sc = s; count-- && *sc != '\0'; ++sc)
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/* nothing */;
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return sc - s;
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}
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int memcmp(const void *cs, const void *ct, size_t count)
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{
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const unsigned char *su1 = cs, *su2 = ct, *end = su1 + count;
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int res = 0;
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while (su1 < end) {
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res = *su1++ - *su2++;
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if (res)
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break;
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}
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return res;
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}
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int strcmp(const char *cs, const char *ct)
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{
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unsigned char c1, c2;
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int res = 0;
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do {
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c1 = *cs++;
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c2 = *ct++;
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res = c1 - c2;
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if (res)
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break;
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} while (c1);
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return res;
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}
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void *memchr(const void *s, int c, size_t count)
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{
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const unsigned char *p = s;
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while (count--)
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if ((unsigned char)c == *p++)
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return (void *)(p - 1);
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return NULL;
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}
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char *strchr(const char *s, int c)
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{
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while (*s != (char)c)
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if (*s++ == '\0')
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return NULL;
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return (char *)s;
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}
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#undef memset
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void *memset(void *s, int c, size_t count)
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{
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char *xs = s;
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while (count--)
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*xs++ = c;
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return s;
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}
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