re PR rtl-optimization/55740 (ICE in verify_loop_structure, at cfgloop.c:1582,…

re PR rtl-optimization/55740 (ICE in verify_loop_structure, at cfgloop.c:1582, error: loop 2's header does not belong directly to it)

2012-12-20  Richard Biener  <rguenther@suse.de>

	PR middle-end/55740
	* cfghooks.c (merge_blocks): Properly handle merging of
	two loop headers.

	* g++.dg/torture/pr55740.C: New testcase.

From-SVN: r194633

gcc/ChangeLog

+2012-12-20  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/55740
+	* cfghooks.c (merge_blocks): Properly handle merging of
+	two loop headers.
+
 2012-12-20  Roland Stigge  <stigge@debian.org>
 	    Matthias Klose  <doko@ubuntu.com>
 

gcc/cfghooks.c

@@ -724,11 +724,23 @@ merge_blocks (basic_block a, basic_block b)
 
   cfg_hooks->merge_blocks (a, b);
 
-  /* If we merge a loop header into its predecessor, update the loop
-     structure.  */
   if (current_loops != NULL)
     {
-      if (b->loop_father->header == b)
+      /* If the block we merge into is a loop header do nothing unless ... */
+      if (a->loop_father->header == a)
+	{
+	  /* ... we merge two loop headers, in which case we kill
+	     the inner loop.  */
+	  if (b->loop_father->header == b)
+	    {
+	      b->loop_father->header = NULL;
+	      b->loop_father->latch = NULL;
+	      loops_state_set (LOOPS_NEED_FIXUP);
+	    }
+	}
+      /* If we merge a loop header into its predecessor, update the loop
+	 structure.  */
+      else if (b->loop_father->header == b)
 	{
 	  remove_bb_from_loops (a);
 	  add_bb_to_loop  (a, b->loop_father);

gcc/testsuite/ChangeLog

+2012-12-20  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/55740
+	* g++.dg/torture/pr55740.C: New testcase.
+
 2012-12-20  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/55619

gcc/testsuite/g++.dg/torture/pr55740.C

+// { dg-do compile }
+
+static bool st_IsPathDelimiter( char c ) { return c == '/'; }
+bool IsValidPath( char const * filename )
+{
+  if ( !filename || filename[0] == 0 )     
+    return false;
+  char const * run = filename;
+  while ( run && *run )       
+    {
+      if ( run[0] == '.' )   
+	if ( run[1] != '.' || ( !st_IsPathDelimiter( run[2] ) && run[2] != 0 ) )   
+	  return false;   
+      while ( *run && !st_IsPathDelimiter( *run ) )
+	++run;
+      if ( *run ) 
+	++run;
+    }
+}