[committed] Fix get_loop_body ICE (PR rtl-optimization/47899)

[Jakub Jelinek]

Hi!

I've committed this patch of Zdenek to fix PR47899 after bootstrap/regtest
on x86_64-linux and i686-linux to trunk, pre-approved in the PR.
Zdenek, if you want to adjust the ChangeLog entry I've made up or use
different e-mail address, just Change it in SVN.  kam.uniff.cz
domain you've used in your last two commits doesn't resolve...

2011-03-05  Zdenek Dvorak  <ook@ucw.cz>

	PR rtl-optimization/47899
	* cfgloopmanip.c (fix_bb_placements): Fix first argument
	to flow_loop_nested_p when moving the loop upward.

	* gcc.dg/pr47899.c: New test.

--- gcc/cfgloopmanip.c.jj	2010-11-03 10:48:15.000000000 +0100
+++ gcc/cfgloopmanip.c	2011-03-02 13:16:50.171526946 +0100
@@ -174,7 +174,7 @@ fix_bb_placements (basic_block from,
 {
   sbitmap in_queue;
   basic_block *queue, *qtop, *qbeg, *qend;
-  struct loop *base_loop;
+  struct loop *base_loop, *target_loop;
   edge e;
 
   /* We pass through blocks back-reachable from FROM, testing whether some
@@ -214,12 +214,14 @@ fix_bb_placements (basic_block from,
 	  /* Subloop header, maybe move the loop upward.  */
 	  if (!fix_loop_placement (from->loop_father))
 	    continue;
+	  target_loop = loop_outer (from->loop_father);
 	}
       else
 	{
 	  /* Ordinary basic block.  */
 	  if (!fix_bb_placement (from))
 	    continue;
+	  target_loop = from->loop_father;
 	}
 
       FOR_EACH_EDGE (e, ei, from->succs)
@@ -248,9 +250,12 @@ fix_bb_placements (basic_block from,
 	      && (nca == base_loop
 		  || nca != pred->loop_father))
 	    pred = pred->loop_father->header;
-	  else if (!flow_loop_nested_p (from->loop_father, pred->loop_father))
+	  else if (!flow_loop_nested_p (target_loop, pred->loop_father))
 	    {
-	      /* No point in processing it.  */
+	      /* If PRED is already higher in the loop hierarchy than the
+		 TARGET_LOOP to that we moved FROM, the change of the position
+		 of FROM does not affect the position of PRED, so there is no
+		 point in processing it.  */
 	      continue;
 	    }
 
--- gcc/testsuite/gcc.dg/pr47899.c.jj	2011-01-16 05:42:39.626675592 +0100
+++ gcc/testsuite/gcc.dg/pr47899.c	2011-03-02 13:23:02.675527008 +0100
@@ -0,0 +1,26 @@
+/* PR rtl-optimization/47899 */
+/* { dg-do compile } */
+/* { dg-options "-O -funroll-loops" } */
+
+extern unsigned int a, b, c;
+extern int d;
+
+static int
+foo (void)
+{
+lab:
+  if (b)
+    for (d = 0; d >= 0; d--)
+      if (a || c)
+	for (; c; c++)
+	  ;
+      else
+	goto lab;
+}
+
+int
+main ()
+{
+  foo ();
+  return 0;
+}

	Jakub