flow.c (flow_loop_scan): Break out of ...

	* flow.c (flow_loop_scan): Break out of ...
	(flow_loops_find) ... here.
	* basic-block.h (flow_loop_scan): New.
	(LOOP_ENTRY_EDGES, LOOP_EXIT_EDGES): Add.
	(LOOP_EDGES, LOOP_EXITS_DOMS, LOOP_ALL): Redefine.

From-SVN: r38822

3 files changed, 84 insertions, 46 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5bc2e8a..81c6a01 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2001-01-09  Michael Hayes  <mhayes@redhat.com>
+
+	* flow.c (flow_loop_scan): Break out of ...
+	(flow_loops_find) ... here.
+	* basic-block.h (flow_loop_scan): New.
+	(LOOP_ENTRY_EDGES, LOOP_EXIT_EDGES): Add.
+	(LOOP_EDGES, LOOP_EXITS_DOMS, LOOP_ALL): Redefine.
+
 2001-01-09  Alexandre Oliva  <aoliva@redhat.com>
 
 	* cppinit.c (cpp_cleanup): NULLify macro_buffer and zero
diff --git a/gcc/basic-block.h b/gcc/basic-block.h
index f86ff3c..c48a547 100644
--- a/gcc/basic-block.h
+++ b/gcc/basic-block.h
@@ -428,6 +428,7 @@ extern void flow_loops_dump PARAMS ((const struct loops *, FILE *,
 extern void flow_loop_dump PARAMS ((const struct loop *, FILE *,
 				    void (*)(const struct loop *,
 					     FILE *, int), int));
+extern int flow_loop_scan PARAMS ((struct loops *, struct loop *, int));
 
 /* This structure maintains an edge list vector.  */
 struct edge_list 
@@ -485,9 +486,11 @@ enum update_life_extent
 
 #define LOOP_TREE		1 	/* Build loop hierarchy tree.  */
 #define LOOP_PRE_HEADER		2	/* Analyse loop pre-header.  */
-#define LOOP_EDGES		4 	/* Find entry and exit edges.  */
-#define LOOP_EXITS_DOMS		8 	/* Find nodes that dom. all exits.  */
-#define LOOP_ALL	       15 	/* All of the above  */
+#define LOOP_ENTRY_EDGES	4 	/* Find entry edges.  */
+#define LOOP_EXIT_EDGES		8 	/* Find exit edges.  */
+#define LOOP_EDGES		(LOOP_ENTRY_EDGES | LOOP_EXIT_EDGES)
+#define LOOP_EXITS_DOMS	       16 	/* Find nodes that dom. all exits.  */
+#define LOOP_ALL	       31 	/* All of the above  */
 
 extern void life_analysis	PARAMS ((rtx, FILE *, int));
 extern void update_life_info	PARAMS ((sbitmap, enum update_life_extent,
diff --git a/gcc/flow.c b/gcc/flow.c
index a53043d..faed23f 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -8137,6 +8137,70 @@ flow_loops_level_compute (loops)
 }
 
 
+/* Scan a single natural loop specified by LOOP collecting information
+   about it specified by FLAGS.  */
+
+int
+flow_loop_scan (loops, loop, flags)
+     struct loops *loops;
+     struct loop *loop;
+     int flags;
+{
+  /* Determine prerequisites.  */
+  if ((flags & LOOP_EXITS_DOMS) && ! loop->exit_edges)
+    flags |= LOOP_EXIT_EDGES;
+
+  if (flags & LOOP_ENTRY_EDGES)
+    {
+      /* Find edges which enter the loop header.
+	 Note that the entry edges should only
+	 enter the header of a natural loop.  */
+      loop->num_entries
+	= flow_loop_entry_edges_find (loop->header,
+				      loop->nodes,
+				      &loop->entry_edges);
+    }
+
+  if (flags & LOOP_EXIT_EDGES)
+    {
+      /* Find edges which exit the loop.  */
+      loop->num_exits
+	= flow_loop_exit_edges_find (loop->nodes,
+				     &loop->exit_edges);
+    }
+
+  if (flags & LOOP_EXITS_DOMS)
+    {
+      int j;
+
+      /* Determine which loop nodes dominate all the exits
+	 of the loop.  */
+      loop->exits_doms = sbitmap_alloc (n_basic_blocks);
+      sbitmap_copy (loop->exits_doms, loop->nodes);
+      for (j = 0; j < loop->num_exits; j++)
+	sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
+			 loops->cfg.dom[loop->exit_edges[j]->src->index]);
+      
+      /* The header of a natural loop must dominate
+	 all exits.  */
+      if (! TEST_BIT (loop->exits_doms, loop->header->index))
+	abort ();
+    }
+  
+  if (flags & LOOP_PRE_HEADER)
+    {
+      /* Look to see if the loop has a pre-header node.  */
+      loop->pre_header
+	= flow_loop_pre_header_find (loop->header, loops->cfg.dom);
+
+      /* Find the blocks within the extended basic block of
+	 the loop pre-header.  */
+      flow_loop_pre_header_scan (loop);
+    }
+  return 1;
+}
+
+
 /* Find all the natural loops in the function and save in LOOPS structure
    and recalculate loop_depth information in basic block structures.
    FLAGS controls which loop information is collected.
@@ -8213,6 +8277,11 @@ flow_loops_find (loops, flags)
       rc_order = (int *) xmalloc (n_basic_blocks * sizeof (int));
       flow_depth_first_order_compute (dfs_order, rc_order);
 
+      /* Save CFG derived information to avoid recomputing it.  */
+      loops->cfg.dom = dom;
+      loops->cfg.dfs_order = dfs_order;
+      loops->cfg.rc_order = rc_order;
+
       /* Allocate loop structures.  */
       loops->array
 	= (struct loop *) xcalloc (num_loops, sizeof (struct loop));
@@ -8264,7 +8333,6 @@ flow_loops_find (loops, flags)
       for (i = 0; i < num_loops; i++)
 	{
 	  struct loop *loop = &loops->array[i];
-	  int j;
 
 	  /* Keep track of blocks that are loop headers so
 	     that we can tell which loops should be merged.  */
@@ -8286,43 +8354,7 @@ flow_loops_find (loops, flags)
 	  loop->last
 	    = BASIC_BLOCK (sbitmap_last_set_bit (loop->nodes));
 
-	  if (flags & LOOP_EDGES)
-	    {
-	      /* Find edges which enter the loop header.
-		 Note that the entry edges should only
-		 enter the header of a natural loop.  */
-	      loop->num_entries
-		= flow_loop_entry_edges_find (loop->header,
-					      loop->nodes,
-					      &loop->entry_edges);
-
-	      /* Find edges which exit the loop.  */
-	      loop->num_exits
-		= flow_loop_exit_edges_find (loop->nodes,
-					     &loop->exit_edges);
-
-	      /* Determine which loop nodes dominate all the exits
-		 of the loop.  */
-	      loop->exits_doms = sbitmap_alloc (n_basic_blocks);
-	      sbitmap_copy (loop->exits_doms, loop->nodes);
-	      for (j = 0; j < loop->num_exits; j++)
-		sbitmap_a_and_b (loop->exits_doms, loop->exits_doms,
-				 dom[loop->exit_edges[j]->src->index]);
-
-	      /* The header of a natural loop must dominate
-		 all exits.  */
-	      if (! TEST_BIT (loop->exits_doms, loop->header->index))
-		abort ();
-	    }
-
-	  if (flags & LOOP_PRE_HEADER)
-	    {
-	      /* Look to see if the loop has a pre-header node.  */
-	      loop->pre_header
-		= flow_loop_pre_header_find (loop->header, dom);
-
-	      flow_loop_pre_header_scan (loop);
-	    }
+	  flow_loop_scan (loops, loop, flags);
 	}
 
       /* Natural loops with shared headers may either be disjoint or
@@ -8338,11 +8370,6 @@ flow_loops_find (loops, flags)
 
   loops->num = num_loops;
 
-  /* Save CFG derived information to avoid recomputing it.  */
-  loops->cfg.dom = dom;
-  loops->cfg.dfs_order = dfs_order;
-  loops->cfg.rc_order = rc_order;
-
   /* Build the loop hierarchy tree.  */
   flow_loops_tree_build (loops);