Do not call BCOPY and BZERO if size is zero

* dbg_mlc.c (GC_debug_strndup): Do not call BCOPY() if elements count
is zero.
* dbg_mlc.c (GC_debug_realloc): Likewise.
* finalize.c [!GC_TOGGLE_REFS_NOT_NEEDED] (ensure_toggleref_capacity):
Likewise.
* malloc.c [REDIRECT_MALLOC && !strndup] (strndup): Likewise.
* mallocx.c (GC_strndup): Likewise.
* misc.c [!GC_GET_HEAP_USAGE_NOT_NEEDED] (GC_get_prof_stats): Likewise.
* os_dep.c [SAVE_CALL_CHAIN && GC_HAVE_BUILTIN_BACKTRACE]
(GC_save_callers): Likewise.
* reclaim.c (GC_print_all_errors): Likewise.
* malloc.c (GC_free): Do not call BZERO() if elements count is zero.
* malloc.c [THREADS] (GC_free_inner): Likewise.
* reclaim.c (GC_print_all_errors): Likewise.
* misc.c [!GC_GET_HEAP_USAGE_NOT_NEEDED && THREADS]
(GC_get_prof_stats_unsafe): Do not call fill_prof_stats() and BCOPY()
if stats_sz is zero.

1 files changed, 4 insertions, 2 deletions

diff --git a/dbg_mlc.c b/dbg_mlc.c
index 724d9cff..4edeeefd 100644
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -760,7 +760,8 @@ GC_API GC_ATTR_MALLOC char * GC_CALL GC_debug_strndup(const char *str,
 #   endif
     return NULL;
   }
-  BCOPY(str, copy, len);
+  if (len > 0)
+    BCOPY(str, copy, len);
   copy[len] = '\0';
   return copy;
 }
@@ -973,7 +974,8 @@ GC_API void * GC_CALL GC_debug_realloc(void * p, size_t lb, GC_EXTRA_PARAMS)
 #     else
         old_sz = ((oh *)base) -> oh_sz;
 #     endif
-      BCOPY(p, result, old_sz < lb ? old_sz : lb);
+      if (old_sz > 0)
+        BCOPY(p, result, old_sz < lb ? old_sz : lb);
       GC_debug_free(p);
     }
     return(result);