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Add volatile to workaround GCC optimization bug in 4.9.2 and greater. #994

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Merged
merged 1 commit into from
Oct 7, 2015
Merged

Add volatile to workaround GCC optimization bug in 4.9.2 and greater. #994

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20 changes: 14 additions & 6 deletions opal/mca/memory/linux/memory_linux.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,12 +32,20 @@ typedef struct opal_memory_linux_component_t {
#endif

#if MEMORY_LINUX_PTMALLOC2
/* Ptmalloc2-specific data */
bool free_invoked;
bool malloc_invoked;
bool realloc_invoked;
bool memalign_invoked;
bool munmap_invoked;
/* Ptmalloc2-specific data. Note that these variables are all marked as volatile.
* This is needed because of what may be a buggy optimization in the GCC 4.9.2
* compilers and later. These variables are used in different code paths which the
* compiler is not aware of.
* Extra details located at these URLs:
* Open MPI User List: http://www.open-mpi.org/community/lists/users/2015/06/27039.php
* Bug Discussion: https://github.com/open-mpi/ompi/pull/625
* GCC Discussion: https://gcc.gnu.org/ml/gcc-bugs/2015-06/msg00757.html
*/
volatile bool free_invoked;
volatile bool malloc_invoked;
volatile bool realloc_invoked;
volatile bool memalign_invoked;
volatile bool munmap_invoked;
#endif
} opal_memory_linux_component_t;

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