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author | Andreas Jaeger <aj@suse.de> | 2012-05-03 22:12:59 +0200 |
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committer | Andreas Jaeger <aj@suse.de> | 2012-05-03 22:12:59 +0200 |
commit | f0c1dedf0df71b4029d9b0ce8ba19d8af2a60af5 (patch) | |
tree | 059f1ba1edcd7ed788946cb33790a17e6c751f0a /malloc/mcheck.c | |
parent | a65ef2aefa3167e531d1df0047df804069a8c36f (diff) | |
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Fix tst-obprintf - and mcheck in general
tst-obprintf failed with GCC 4.7.
It turned out that this is the fault of GCC optimizing away the
following from malloc/mcheck.c:
/* We call malloc() once here to ensure it is initialized. */
void *p = malloc (0);
free (p);
gcc sees the malloc(0);free pair and removes it completely.
And now malloc is not properly initialized and we screw up if both
mcheck is used (via tst-obprintf) and MALLOC_CHECK_ is set (as it is in my
environment).
Diffstat (limited to 'malloc/mcheck.c')
-rw-r--r-- | malloc/mcheck.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/malloc/mcheck.c b/malloc/mcheck.c index 9213740..9d8a414 100644 --- a/malloc/mcheck.c +++ b/malloc/mcheck.c @@ -370,6 +370,10 @@ mabort (enum mcheck_status status) #endif } +/* Memory barrier so that GCC does not optimize out the argument. */ +#define malloc_opt_barrier(x) \ +({ __typeof (x) __x = x; __asm ("" : "+m" (__x)); __x; }) + int mcheck (func) void (*func) (enum mcheck_status); @@ -381,6 +385,8 @@ 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; |