[Support] Make GetMallocUsage() aware of jemalloc

[davide]

Summary

When getting info about heap usage (e.g. ld --stats) I think it is desiderable to have something more fine-grained than sbrk() on systems where the default allocator is jemalloc (namely, FreeBSD). I wasn't sure who to put as reviewer to this change, feel free to comment. Also, I noticed that GetMallocUsage() isn't unit-tested (or at least I didn't find where it is unit-tested), so, maybe , enhancing the testing coverage might be considered in this (or a subsequent) commit.

[majnemer]

lib/Support/Unix/Process.inc

109–110

No need for an else.

[davide]

I do agree with you and I'm generally a big fan of avoiding 'else' unless necessary but a couple of lines below that if/else is used so I'd keep that for consistency and (eventually) change in a subsequent commit, in order to not mix style/functional modifications.
Does this make sense to you?

[majnemer]

In D7663#125254, @davide wrote:

I do agree with you and I'm generally a big fan of avoiding 'else' unless necessary but a couple of lines below that if/else is used so I'd keep that for consistency and (eventually) change in a subsequent commit, in order to not mix style/functional modifications.
Does this make sense to you?

Makes sense.

cmake/config-ix.cmake

   check_symbol_exists(writev sys/uio.h HAVE_WRITEV)
 endif()
 check_symbol_exists(nearbyintf math.h HAVE_NEARBYINTF)
+check_symbol_exists(mallctl malloc_np.h HAVE_MALLCTL)
 check_symbol_exists(mallinfo malloc.h HAVE_MALLINFO)
 check_symbol_exists(malloc_zone_statistics malloc/malloc.h
                     HAVE_MALLOC_ZONE_STATISTICS)

include/llvm/Config/config.h.cmake

 /* Define to 1 if you have the `malloc_zone_statistics' function. */
 #cmakedefine HAVE_MALLOC_ZONE_STATISTICS ${HAVE_MALLOC_ZONE_STATISTICS}
 
+/* Define to 1 if you have the `mallctl` function. */
+#cmakedefine HAVE_MALLCTL ${HAVE_MALLCTL}
+
 /* Define to 1 if you have the `mkdtemp' function. */
 #cmakedefine HAVE_MKDTEMP ${HAVE_MKDTEMP}
 

include/llvm/Config/config.h.in

 /* Define if mallinfo() is available on this platform. */
 #undef HAVE_MALLINFO
 
+/* Define if mallctl() is available on this plaform. */
+#undef HAVE_MALLCTL
+
 /* Define to 1 if you have the <malloc.h> header file. */
 #undef HAVE_MALLOC_H
 

lib/Support/Unix/Process.inc

     !defined(__OpenBSD__) && !defined(__Bitrig__)
 #include <malloc.h>
 #endif
+#if defined(HAVE_MALLCTL)
+#include <malloc_np.h>
+#endif
 #ifdef HAVE_MALLOC_MALLOC_H
 #include <malloc/malloc.h>
 #endif

   malloc_statistics_t Stats;
   malloc_zone_statistics(malloc_default_zone(), &Stats);
   return Stats.size_in_use;   // darwin
+#elif defined(HAVE_MALLCTL)
+  size_t alloc, sz;
+  sz = sizeof(size_t);
+  if (mallctl("stats.allocated", &alloc, &sz, NULL, 0) == 0)
+    return alloc;
+  else
+    return 0;
 #elif defined(HAVE_SBRK)
   // Note this is only an approximation and more closely resembles
   // the value returned by mallinfo in the arena field.