re PR tree-optimization/56264 (ICE in check_loop_closed_ssa_use, at tree-ssa-loop-manip.c:557)

2013-02-11  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56264
	* cfgloop.h (fix_loop_structure): Adjust prototype.
	* loop-init.c (fix_loop_structure): Return the number of
	newly discovered loops.
	* tree-cfgcleanup.c (repair_loop_structures): When new loops
	are discovered, do a full loop-closed SSA rewrite.

	* gcc.dg/torture/pr56264.c: New testcase.

From-SVN: r195941

gcc/ChangeLog

 2013-02-11  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/56264
+	* cfgloop.h (fix_loop_structure): Adjust prototype.
+	* loop-init.c (fix_loop_structure): Return the number of
+	newly discovered loops.
+	* tree-cfgcleanup.c (repair_loop_structures): When new loops
+	are discovered, do a full loop-closed SSA rewrite.
+
+2013-02-11  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/56273
 	* tree-vrp.c (simplify_cond_using_ranges): Disable for the
 	first VRP run.

gcc/cfgloop.h

@@ -216,7 +216,7 @@ extern void flow_loop_dump (const struct loop *, FILE *,
 struct loop *alloc_loop (void);
 extern void flow_loop_free (struct loop *);
 int flow_loop_nodes_find (basic_block, struct loop *);
-void fix_loop_structure (bitmap changed_bbs);
+unsigned fix_loop_structure (bitmap changed_bbs);
 bool mark_irreducible_loops (void);
 void release_recorded_exits (void);
 void record_loop_exits (void);

gcc/loop-init.c

@@ -171,16 +171,19 @@ loop_fini_done:
    the latch, and loops did not get new subloops (new loops might possibly
    get created, but we are not interested in them).  Fix up the mess.
 
-   If CHANGED_BBS is not NULL, basic blocks whose loop has changed are
-   marked in it.  */
+   If CHANGED_BBS is not NULL, basic blocks whose loop depth has changed are
+   marked in it.
 
-void
+   Returns the number of new discovered loops.  */
+
+unsigned
 fix_loop_structure (bitmap changed_bbs)
 {
   basic_block bb;
   int record_exits = 0;
   loop_iterator li;
   struct loop *loop;
+  unsigned old_nloops;
 
   timevar_push (TV_LOOP_INIT);
 
@@ -228,6 +231,10 @@ fix_loop_structure (bitmap changed_bbs)
       delete_loop (loop);
     }
 
+  /* Remember the number of loops so we can return how many new loops
+     flow_loops_find discovered.  */
+  old_nloops = number_of_loops ();
+
   /* Re-compute loop structure in-place.  */
   flow_loops_find (current_loops);
 
@@ -253,6 +260,8 @@ fix_loop_structure (bitmap changed_bbs)
 #endif
 
   timevar_pop (TV_LOOP_INIT);
+
+  return number_of_loops () - old_nloops;
 }
 
 /* Gate for the RTL loop superpass.  The actual passes are subpasses.

gcc/testsuite/ChangeLog

 2013-02-11  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/56264
+	* gcc.dg/torture/pr56264.c: New testcase.
+
+2013-02-11  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/56273
 	* g++.dg/warn/Warray-bounds-6.C: New testcase.
 	* gcc.dg/tree-ssa/pr21559.c: Adjust.

gcc/testsuite/gcc.dg/torture/pr56264.c

+/* { dg-do compile } */
+/* { dg-options "-funswitch-loops" } */
+
+int a, b, c;
+
+void f(void)
+{
+  if(b)
+    {
+      for(a = 0; a < 1; a++)
+	lbl:
+	    c = c && b ? : 0;
+
+      c = 0;
+      goto lbl;
+    }
+
+  if(a)
+    goto lbl;
+}

gcc/tree-cfgcleanup.c

@@ -707,18 +707,22 @@ static void
 repair_loop_structures (void)
 {
   bitmap changed_bbs;
+  unsigned n_new_loops;
 
   calculate_dominance_info (CDI_DOMINATORS);
 
   timevar_push (TV_REPAIR_LOOPS);
   changed_bbs = BITMAP_ALLOC (NULL);
-  fix_loop_structure (changed_bbs);
+  n_new_loops = fix_loop_structure (changed_bbs);
 
   /* This usually does nothing.  But sometimes parts of cfg that originally
      were inside a loop get out of it due to edge removal (since they
-     become unreachable by back edges from latch).  */
+     become unreachable by back edges from latch).  Also a former
+     irreducible loop can become reducible - in this case force a full
+     rewrite into loop-closed SSA form.  */
   if (loops_state_satisfies_p (LOOP_CLOSED_SSA))
-    rewrite_into_loop_closed_ssa (changed_bbs, TODO_update_ssa);
+    rewrite_into_loop_closed_ssa (n_new_loops ? NULL : changed_bbs,
+				  TODO_update_ssa);
 
   BITMAP_FREE (changed_bbs);