re PR tree-optimization/56350 (ICE in vectorizable_reduction, at tree-vect-loop.c:4731)

2013-02-18  Richard Biener  <rguenther@suse.de>

	PR middle-end/56350
	* cfghooks.c (merge_blocks): If we merge a latch into another
	block adjust references to it.
	* cfgloop.c (flow_loops_find): Reset latch before recomputing it.
	(verify_loop_structure): Verify that a recorded latch is in fact
	a latch.

	* gcc.dg/torture/pr56350.c: New testcase.

From-SVN: r196118

gcc/ChangeLog

 2013-02-18  Richard Biener  <rguenther@suse.de>
 
+	PR middle-end/56350
+	* cfghooks.c (merge_blocks): If we merge a latch into another
+	block adjust references to it.
+	* cfgloop.c (flow_loops_find): Reset latch before recomputing it.
+	(verify_loop_structure): Verify that a recorded latch is in fact
+	a latch.
+
+2013-02-18  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/56321
 	* tree-ssa-reassoc.c (propagate_op_to_single_use): Properly
 	order SSA name release and virtual operand unlinking.

gcc/cfghooks.c

@@ -761,7 +761,12 @@ merge_blocks (basic_block a, basic_block b)
     {
       e->src = a;
       if (current_loops != NULL)
-	rescan_loop_exit (e, true, false);
+	{
+	  /* If b was a latch, a now is.  */
+	  if (e->dest->loop_father->latch == b)
+	    e->dest->loop_father->latch = a;
+	  rescan_loop_exit (e, true, false);
+	}
     }
   a->succs = b->succs;
   a->flags |= b->flags;

gcc/cfgloop.c

@@ -466,6 +466,8 @@ flow_loops_find (struct loops *loops)
 			 "loop %d with header %d\n",
 			 loop->num, header->index);
 	    }
+	  /* Reset latch, we recompute it below.  */
+	  loop->latch = NULL;
 	  larray.safe_push (loop);
 	}
 
@@ -1413,6 +1415,19 @@ verify_loop_structure (void)
 	  error ("loop %d%'s header does not have exactly 2 entries", i);
 	  err = 1;
 	}
+      if (loop->latch)
+	{
+	  if (!find_edge (loop->latch, loop->header))
+	    {
+	      error ("loop %d%'s latch does not have an edge to its header", i);
+	      err = 1;
+	    }
+	  if (!dominated_by_p (CDI_DOMINATORS, loop->latch, loop->header))
+	    {
+	      error ("loop %d%'s latch is not dominated by its header", i);
+	      err = 1;
+	    }
+	}
       if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
 	{
 	  if (!single_succ_p (loop->latch))

gcc/testsuite/ChangeLog

 2013-02-18  Richard Biener  <rguenther@suse.de>
 
+	PR middle-end/56350
+	* gcc.dg/torture/pr56350.c: New testcase.
+
+2013-02-18  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/56321
 	* gcc.dg/torture/pr56321.c: New testcase.
 

gcc/testsuite/gcc.dg/torture/pr56350.c

+/* { dg-do compile } */
+
+int a, b;
+short c;
+
+void f(void)
+{
+  int a = 0;
+  int *k = 0;
+
+  for(; a < 2; a++);
+
+  if(!!(b |= a < 3) - 1)
+    {
+      if(0)
+	for (;; a++)
+	  {
+	    for (; c; *k = 0);
+lbl1:
+	    ;
+	  }
+
+      for(; *k; k++)
+	{
+	  c = b ? : a;
+
+	  if (c)
+	    lbl2:
+		b = 0;
+	}
+      goto lbl1;
+    }
+
+  for(;; b++)
+    {
+      if(b)
+	goto lbl2;
+
+      k = &b;
+    }
+}