* cfgloop.c (flow_loops_find): Use the information of the depth

        first search order of the CFG correctly when finding natural loops.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@48227 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 14 insertions, 14 deletions

diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c
index cabd2f22299..a94cbfe79b9 100644
--- a/gcc/cfgloop.c
+++ b/gcc/cfgloop.c
@@ -737,26 +737,26 @@ flow_loops_find (loops, flags)
       /* Find and record information about all the natural loops
 	 in the CFG.  */
       num_loops = 0;
-      for (b = 0; b < n_basic_blocks; b++)
+      for (b = n_basic_blocks - 1; b >= 0; b--)
 	{
-	  basic_block header;
+	  basic_block latch;
 
 	  /* Search the nodes of the CFG in reverse completion order
 	     so that we can find outer loops first.  */
-	  header = BASIC_BLOCK (rc_order[b]);
+	  latch = BASIC_BLOCK (rc_order[b]);
 
-	  /* Look for all the possible latch blocks for this header.  */
-	  for (e = header->pred; e; e = e->pred_next)
+	  /* Look for all the possible headers for this latch block.  */
+	  for (e = latch->succ; e; e = e->succ_next)
 	    {
-	      basic_block latch = e->src;
-
-	      /* Look for back edges where a predecessor is dominated
-		 by this block.  A natural loop has a single entry
-		 node (header) that dominates all the nodes in the
-		 loop.  It also has single back edge to the header
-		 from a latch node.  Note that multiple natural loops
-		 may share the same header.  */
-	      if (latch != ENTRY_BLOCK_PTR
+	      basic_block header = e->dest;
+
+	      /* Look for forward edges where this block is dominated by
+		 a successor of this block.  A natural loop has a single
+		 entry node (header) that dominates all the nodes in the
+		 loop.  It also has single back edge to the header from a
+		 latch node.  Note that multiple natural loops may share
+		 the same header.  */
+	      if (header != EXIT_BLOCK_PTR
 		  && TEST_BIT (dom[latch->index], header->index))
 		{
 		  struct loop *loop;