From 544048ecef8fd8480d850fe80ba04ab9d7f8bdef Mon Sep 17 00:00:00 2001
From: David Schultz <das@FreeBSD.org>
Date: Sat, 31 Jan 2009 18:27:02 +0000
Subject: [PATCH] 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 +-
sys/sys/cdefs.h | 2 ++
sys/sys/malloc.h | 4 ++--
5 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/include/stdlib.h b/include/stdlib.h
index 0a8327066bd7..91be536668b7 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 32a9ad3e5608..4770d101a139 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 2326b1debb50..4fc6c8cb03b2 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);
diff --git a/sys/sys/cdefs.h b/sys/sys/cdefs.h
index e796908d9e3d..a85095075ab9 100644
--- a/sys/sys/cdefs.h
+++ b/sys/sys/cdefs.h
@@ -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
diff --git a/sys/sys/malloc.h b/sys/sys/malloc.h
index 33b287f83d92..24a044c2c6c4 100644
--- a/sys/sys/malloc.h
+++ b/sys/sys/malloc.h
@@ -190,9 +190,9 @@ typedef void malloc_type_list_func_t(struct malloc_type *, void *);
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);