From: Paul Pluzhnikov <ppluzhnikov@google.com>
Date: Mon, 31 Oct 2011 23:27:54 +0000 (-0700)
Subject: Use extend_alloca in _dl_map_object_deps.
X-Git-Tag: glibc-2.15~125
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=02f9c6cfe286ebd1f39106ae77245c5514ec6919;p=thirdparty%2Fglibc.git

Use extend_alloca in _dl_map_object_deps.
---

diff --git a/ChangeLog b/ChangeLog
index 83a64e83580..6e247ec4455 100644
--- 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 95b1088f22e..a1ba3d1d325 100644
--- 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])
 	{