2010-11-26 13:24:51

by Davidlohr Bueso

Subject: [PATCH] perf: add GCC optimization to memory allocating functions

From: Davidlohr Bueso <[email protected]>

We can benefit from the alloc_size attribute in xrealloc and zalloc.

Signed-off-by: Davidlohr Bueso <[email protected]>
---
tools/perf/util/util.h | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 7562707..41a5067 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -182,10 +182,11 @@ static inline char *gitstrchrnul(const char *s, int c)
* Wrappers:
*/
extern char *xstrdup(const char *str);
-extern void *xrealloc(void *ptr, size_t size) __attribute__((weak));
+extern void *xrealloc(void *ptr, size_t size) __attribute__((weak, alloc_size(2)));


-static inline void *zalloc(size_t size)
+static inline __attribute__((alloc_size(1)))
+void *zalloc(size_t size)
{
return calloc(1, size);
}
--
1.7.1

2010-11-26 13:27:13

by Peter Zijlstra

Subject: Re: [PATCH] perf: add GCC optimization to memory allocating functions

On Fri, 2010-11-26 at 10:24 -0300, Davidlohr Bueso wrote:
> From: Davidlohr Bueso <[email protected]>
>
> We can benefit from the alloc_size attribute in xrealloc and zalloc.

What's this alloc_size attribute do?

2010-11-26 13:36:12

by Davidlohr Bueso

Subject: Re: [PATCH] perf: add GCC optimization to memory allocating functions

On Fri, 2010-11-26 at 14:27 +0100, Peter Zijlstra wrote:
> On Fri, 2010-11-26 at 10:24 -0300, Davidlohr Bueso wrote:
> > From: Davidlohr Bueso <[email protected]>
> >
> > We can benefit from the alloc_size attribute in xrealloc and zalloc.
>
> What's this alloc_size attribute do?
>
Quoting from http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html:

"The alloc_size attribute is used to tell the compiler that the function
return value points to memory, where the size is given by one or two of
the functions parameters. GCC uses this information to improve the
correctness of __builtin_object_size."