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Re: Fix tst-obprintf - and mcheck in general
- From: Andreas Jaeger <aj at suse dot com>
- To: libc-alpha at sourceware dot org
- Date: Thu, 03 May 2012 20:32:04 +0200
- Subject: Re: Fix tst-obprintf - and mcheck in general
- References: <201204261453.08679.aj@suse.com> <m21una642x.fsf@igel.home> <Pine.LNX.4.64.1204261500570.23071@jbgna.fhfr.qr> <201204261515.48450.aj@suse.com> <4FA19898.5010901@suse.com>
Here's an updated patch.
Tested on Linux/x86-64 and x86. Ok to commit?
Andreas
2012-05-03 Andreas Jaeger <aj@suse.de>
* malloc/mcheck.c (mcheck): Add barrier so that malloc/free pair
does not get optimized out.
(malloc_opt_barrier): New.
diff --git a/malloc/mcheck.c b/malloc/mcheck.c
index 9213740..d9e1bf9 100644
--- a/malloc/mcheck.c
+++ b/malloc/mcheck.c
@@ -370,6 +370,9 @@ mabort (enum mcheck_status status)
#endif
}
+#define malloc_opt_barrier(x) \
+({ __typeof (x) __x = x; __asm ("" : "+m" (__x)); __x; })
+
int
mcheck (func)
void (*func) (enum mcheck_status);
@@ -381,6 +384,8 @@ mcheck (func)
{
/* We call malloc() once here to ensure it is initialized. */
void *p = malloc (0);
+ /* GCC might optimize out the malloc/free pair without a barrier. */
+ p = malloc_opt_barrier (p);
free (p);
old_free_hook = __free_hook;
--
Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
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