Use extend_alloca in _dl_map_object_deps.

diff --git a/ChangeLog b/ChangeLog
index 83a64e8..6e247ec 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-10-31  Paul Pluzhnikov  <ppluzhnikov@google.com>
+
+       * elf/dl-deps.c (_dl_map_object_deps): Reuse alloca space to reduce
+       stack usage.
+
 2011-10-31  Ulrich Drepper  <drepper@gmail.com>
 
        [BZ #13367]

diff --git a/elf/dl-deps.c b/elf/dl-deps.c
index 95b1088..a1ba3d1 100644 (file)
--- a/elf/dl-deps.c
+++ b/elf/dl-deps.c
@@ -188,6 +188,10 @@ _dl_map_object_deps (struct link_map *map,
   /* Pointer to last unique object.  */
   tail = &known[nlist - 1];
 
+  /* No alloca'd space yet.  */
+  struct link_map **needed_space = NULL;
+  size_t needed_space_bytes = 0;
+
   /* Process each element of the search list, loading each of its
      auxiliary objects and immediate dependencies.  Auxiliary objects
      will be added in the list before the object itself and
@@ -216,8 +220,19 @@ _dl_map_object_deps (struct link_map *map,
         dependencies of this object.  */
       if (l->l_searchlist.r_list == NULL && l->l_initfini == NULL
          && l != map && l->l_ldnum > 0)
-       needed = (struct link_map **) alloca (l->l_ldnum
-                                             * sizeof (struct link_map *));
+       {
+         /* 16-align so extend_alloca has a chance to re-use the space.
+            Note that extend_alloca is broken for recent versions of GCC
+            on x86: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50938  */
+         size_t new_size
+            = (l->l_ldnum * sizeof (struct link_map *) + 15) & ~15;
+
+         if (new_size > needed_space_bytes)
+           needed_space
+              = extend_alloca (needed_space, needed_space_bytes, new_size);
+
+         needed = needed_space;
+       }
 
       if (l->l_info[DT_NEEDED] || l->l_info[AUXTAG] || l->l_info[FILTERTAG])
        {