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.

1 files changed, 1 insertions, 1 deletions

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);