Author: das
Date: Sat Jan 31 18:27:02 2009
New Revision: 187961
URL: http://svn.freebsd.org/changeset/base/187961
Log:
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.
Modified:
head/include/stdlib.h
head/include/string.h
head/include/wchar.h
head/sys/sys/cdefs.h
head/sys/sys/malloc.h
Modified: head/include/stdlib.h
==============================================================================
--- head/include/stdlib.h Sat Jan 31 18:06:34 2009 (r187960)
+++ head/include/stdlib.h Sat Jan 31 18:27:02 2009 (r187961)
@@ -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);
Modified: head/include/string.h
==============================================================================
--- head/include/string.h Sat Jan 31 18:06:34 2009 (r187960)
+++ head/include/string.h Sat Jan 31 18:27:02 2009 (r187961)
@@ -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 c
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;
Modified: head/include/wchar.h
==============================================================================
--- head/include/wchar.h Sat Jan 31 18:06:34 2009 (r187960)
+++ head/include/wchar.h Sat Jan 31 18:27:02 2009 (r187961)
@@ -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);
Modified: head/sys/sys/cdefs.h
==============================================================================
--- head/sys/sys/cdefs.h Sat Jan 31 18:06:34 2009 (r187960)
+++ head/sys/sys/cdefs.h Sat Jan 31 18:27:02 2009 (r187961)
@@ -221,8 +221,10 @@
#endif
#if __GNUC_PREREQ__(2, 96)
+#define __malloc_like __attribute__((__malloc__))
#define __pure __attribute__((__pure__))
#else
+#define __malloc_like
#define __pure
#endif
Modified: head/sys/sys/malloc.h
==============================================================================
--- head/sys/sys/malloc.h Sat Jan 31 18:06:34 2009 (r187960)
+++ head/sys/sys/malloc.h Sat Jan 31 18:27:02 2009 (r187961)
@@ -190,9 +190,9 @@ typedef void malloc_type_list_func_t(str
void contigfree(void *addr, unsigned long size, struct malloc_type *type);
void *contigmalloc(unsigned long size, struct malloc_type *type, int flags,
vm_paddr_t low, vm_paddr_t high, unsigned long alignment,
- unsigned long boundary);
+ unsigned long boundary) __malloc_like;
void free(void *addr, struct malloc_type *type);
-void *malloc(unsigned long size, struct malloc_type *type, int flags);
+void *malloc(unsigned long size, struct malloc_type *type, int flags)
__malloc_like;
void malloc_init(void *);
int malloc_last_fail(void);
void malloc_type_allocated(struct malloc_type *type, unsigned long size);
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