From 61dc3e056cc2ad51f33f296f1cfda0ece440b85e Mon Sep 17 00:00:00 2001 From: das Date: Sat, 31 Jan 2009 18:27:02 +0000 Subject: Add a function attribute called `__malloc_like', which informs gcc that the annotated function returns a pointer that doesn't alias any extant pointer. This results in a 50%+ speedup in microbenchmarks such as the following: char *cp = malloc(1), *buf = malloc(BUF); for (i = 0; i < BUF; i++) buf[i] = *cp; In real programs, your mileage will vary. Note that gcc already performs this optimization automatically for any function called `malloc', `calloc', `strdup', or `strndup' unless -fno-builtins is used. --- include/stdlib.h | 4 ++-- include/string.h | 4 ++-- include/wchar.h | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/stdlib.h b/include/stdlib.h index 0a83270..91be536 100644 --- a/include/stdlib.h +++ b/include/stdlib.h @@ -88,14 +88,14 @@ int atoi(const char *); long atol(const char *); void *bsearch(const void *, const void *, size_t, size_t, int (*)(const void *, const void *)); -void *calloc(size_t, size_t); +void *calloc(size_t, size_t) __malloc_like; div_t div(int, int) __pure2; void exit(int) __dead2; void free(void *); char *getenv(const char *); long labs(long) __pure2; ldiv_t ldiv(long, long) __pure2; -void *malloc(size_t); +void *malloc(size_t) __malloc_like; int mblen(const char *, size_t); size_t mbstowcs(wchar_t * __restrict , const char * __restrict, size_t); int mbtowc(wchar_t * __restrict, const char * __restrict, size_t); diff --git a/include/string.h b/include/string.h index 32a9ad3..4770d10 100644 --- a/include/string.h +++ b/include/string.h @@ -78,7 +78,7 @@ int strcoll(const char *, const char *); char *strcpy(char * __restrict, const char * __restrict); size_t strcspn(const char *, const char *) __pure; #if __POSIX_VISIBLE >= 200112 || __XSI_VISIBLE -char *strdup(const char *); +char *strdup(const char *) __malloc_like; #endif char *strerror(int); #if __POSIX_VISIBLE >= 200112 @@ -96,7 +96,7 @@ char *strncat(char * __restrict, const char * __restrict, size_t); int strncmp(const char *, const char *, size_t) __pure; char *strncpy(char * __restrict, const char * __restrict, size_t); #if __BSD_VISIBLE -char *strndup(const char *, size_t); +char *strndup(const char *, size_t) __malloc_like; char *strnstr(const char *, const char *, size_t) __pure; #endif char *strpbrk(const char *, const char *) __pure; diff --git a/include/wchar.h b/include/wchar.h index 2326b1d..4fc6c8c 100644 --- a/include/wchar.h +++ b/include/wchar.h @@ -214,7 +214,7 @@ int wcwidth(wchar_t); wchar_t *fgetwln(struct __sFILE * __restrict, size_t * __restrict); size_t mbsnrtowcs(wchar_t * __restrict, const char ** __restrict, size_t, size_t, mbstate_t * __restrict); -wchar_t *wcsdup(const wchar_t *); +wchar_t *wcsdup(const wchar_t *) __malloc_like; size_t wcsnrtombs(char * __restrict, const wchar_t ** __restrict, size_t, size_t, mbstate_t * __restrict); size_t wcslcat(wchar_t *, const wchar_t *, size_t); -- cgit v1.1