Revert "Improve verification of loop->latch in verify_loop_structure"

2015-11-26  Tom de Vries  <tom@codesourcery.com>

	revert:
	2015-11-25  Tom de Vries  <tom@codesourcery.com>

	* cfgloop.c (find_single_latch): New function, factored out of ...
	(flow_loops_find): ... here.
	(verify_loop_structure): Improve verification of loop->latch.
	* cfgloop.h (find_single_latch): Declare.
	* omp-low.c (expand_omp_for_generic): Initialize latch of orig_loop.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@230967 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 31 insertions, 52 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8609f0dcdaf..da80e714099 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2015-11-26  Tom de Vries  <tom@codesourcery.com>
+
+	revert:
+	2015-11-25  Tom de Vries  <tom@codesourcery.com>
+
+	* cfgloop.c (find_single_latch): New function, factored out of ...
+	(flow_loops_find): ... here.
+	(verify_loop_structure): Improve verification of loop->latch.
+	* cfgloop.h (find_single_latch): Declare.
+	* omp-low.c (expand_omp_for_generic): Initialize latch of orig_loop.
+
 2015-11-26  Matthew Wahab  <matthew.wahab@arm.com>
 
 	* config/aarch64/aarch64-simd-builtins.def:
diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c
index e7cb78a5351..83a526276db 100644
--- a/gcc/cfgloop.c
+++ b/gcc/cfgloop.c
@@ -388,33 +388,6 @@ bb_loop_header_p (basic_block header)
   return false;
 }
 
-/* Return the latch block for this header block, if it has just a single one.
-   Otherwise, return NULL.  */
-
-basic_block
-find_single_latch (struct loop* loop)
-{
-  basic_block header = loop->header;
-  edge_iterator ei;
-  edge e;
-  basic_block latch = NULL;
-
-  FOR_EACH_EDGE (e, ei, header->preds)
-    {
-      basic_block cand = e->src;
-      if (!flow_bb_inside_loop_p (loop, cand))
-	continue;
-
-      if (latch != NULL)
-	/* More than one latch edge.  */
-	return NULL;
-
-      latch = cand;
-    }
-
-  return latch;
-}
-
 /* Find all the natural loops in the function and save in LOOPS structure and
    recalculate loop_father information in basic block structures.
    If LOOPS is non-NULL then the loop structures for already recorded loops
@@ -509,10 +482,29 @@ flow_loops_find (struct loops *loops)
     {
       struct loop *loop = larray[i];
       basic_block header = loop->header;
+      edge_iterator ei;
+      edge e;
 
       flow_loop_tree_node_add (header->loop_father, loop);
       loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
-      loop->latch = find_single_latch (loop);
+
+      /* Look for the latch for this header block, if it has just a
+	 single one.  */
+      FOR_EACH_EDGE (e, ei, header->preds)
+	{
+	  basic_block latch = e->src;
+
+	  if (flow_bb_inside_loop_p (loop, latch))
+	    {
+	      if (loop->latch != NULL)
+		{
+		  /* More than one latch edge.  */
+		  loop->latch = NULL;
+		  break;
+		}
+	      loop->latch = latch;
+	    }
+	}
     }
 
   return loops;
@@ -1442,28 +1434,6 @@ verify_loop_structure (void)
 	      error ("loop %d%'s latch is not dominated by its header", i);
 	      err = 1;
 	    }
-	  if (find_single_latch (loop) == NULL)
-	    {
-	      error ("loop %d%'s latch is is not the only latch", i);
-	      err = 1;
-	    }
-	}
-      else
-	{
-	  if (loops_state_satisfies_p (LOOPS_MAY_HAVE_MULTIPLE_LATCHES))
-	    {
-	      if (find_single_latch (loop) != NULL)
-		{
-		  error ("loop %d%'s latch is missing", i);
-		  err = 1;
-		}
-	    }
-	  else
-	    {
-	      error ("loop %d%'s latch is missing, and loops may not have"
-		     " multiple latches", i);
-	      err = 1;
-	    }
 	}
       if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
 	{
diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index 7faf591796f..ee73bf994c1 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -270,7 +270,6 @@ bool mark_irreducible_loops (void);
 void release_recorded_exits (function *);
 void record_loop_exits (void);
 void rescan_loop_exit (edge, bool, bool);
-basic_block find_single_latch (struct loop*);
 
 /* Loop data structure manipulation/querying.  */
 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 0b44588b5a1..f17a828330a 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -8907,7 +8907,6 @@ expand_omp_for_generic (struct omp_region *region,
 	  orig_loop->header = l1_bb;
 	  /* The loop may have multiple latches.  */
 	  add_loop (orig_loop, new_loop);
-	  orig_loop->latch = find_single_latch (orig_loop);
 	}
     }
 }