[backport gcc-4.7/trunk r182919 PR49710 fix which reportedly
 also fixes PR48813 <mikpe@it.uu.se>]

gcc/

2012-01-05  Jan Hubicka  <jh@suse.cz>

	PR middle-end/49710
	* cfgloopmanip.c (remove_path): Walk loop hiearchy upwards when
	unlooping loops.

gcc/testsuite/

2012-01-05  Jan Hubicka  <jh@suse.cz>

	PR middle-end/49710
	* gcc.c-torture/compile/pr49710.c: New file.

--- gcc-4.6.2/gcc/cfgloopmanip.c.~1~	2011-03-07 17:41:53.000000000 +0100
+++ gcc-4.6.2/gcc/cfgloopmanip.c	2012-02-18 20:39:09.000000000 +0100
@@ -290,6 +290,7 @@ remove_path (edge e)
   int i, nrem, n_bord_bbs;
   sbitmap seen;
   bool irred_invalidated = false;
+  struct loop *l, *f;
 
   if (!can_remove_branch_p (e))
     return false;
@@ -313,10 +314,12 @@ remove_path (edge e)
      we belong to.  In this case first unloop the loops, then proceed
      normally.   We may assume that e->dest is not a header of any loop,
      as it now has exactly one predecessor.  */
-  while (loop_outer (e->src->loop_father)
-	 && dominated_by_p (CDI_DOMINATORS,
-			    e->src->loop_father->latch, e->dest))
-    unloop (e->src->loop_father, &irred_invalidated);
+  for (l = e->src->loop_father; loop_outer (l); l = f)
+    {
+      f = loop_outer (l);
+      if (dominated_by_p (CDI_DOMINATORS, l->latch, e->dest))
+        unloop (l, &irred_invalidated);
+    }
 
   /* Identify the path.  */
   nrem = find_path (e, &rem_bbs);
--- gcc-4.6.2/gcc/testsuite/gcc.c-torture/compile/pr49710.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.2/gcc/testsuite/gcc.c-torture/compile/pr49710.c	2012-02-18 20:39:09.000000000 +0100
@@ -0,0 +1,35 @@
+int a, b, c, d;
+
+static void
+foo (int *x)
+{
+  c = 0;
+  while (1)
+    {
+      if (*x)
+break;
+      while (b)
+for (; c; c = 0);
+      for (d = 18; d != 18; d++)
+if (c)
+  {
+    foo (x);
+    return;
+  }
+    }
+}
+
+static void
+bar ()
+{
+  foo (0);
+  foo (0);
+  for (;;)
+    ;
+}
+
+baz ()
+{
+  for (; a;)
+    bar ();
+}