http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53695
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-27
10:32:53 UTC ---
I am testing
Index: gcc/cfgloop.c
===================================================================
*** gcc/cfgloop.c (revision 188987)
--- gcc/cfgloop.c (working copy)
*************** init_loops_structure (struct loops *loop
*** 365,370 ****
--- 365,406 ----
loops->tree_root = root;
}
+ /* Return true if there is a path from FROM to the dominated TO where no
+ edge on that path contains FLAGS. */
+
+ static bool
+ path_without_edge_flags (basic_block from, basic_block to, int flags)
+ {
+ do
+ {
+ /* At least one such path to the immediate dominator. */
+ if (single_pred_p (to))
+ {
+ edge e = single_pred_edge (to);
+ if (e->flags & flags)
+ return false;
+ to = e->src;
+ }
+ else
+ {
+ basic_block dom = get_immediate_dominator (CDI_DOMINATORS, to);
+ edge_iterator ei;
+ edge e;
+
+ FOR_EACH_EDGE(e, ei, to->preds)
+ if (!(e->flags & flags)
+ && (e->src == dom
+ || path_without_edge_flags (dom, e->src, flags)))
+ break;
+
+ to = dom;
+ }
+ }
+ while (to != from);
+
+ return true;
+ }
+
/* Find all the natural loops in the function and save in LOOPS structure and
recalculate loop_depth information in basic block structures.
Return the number of natural loops found. */
*************** flow_loops_find (struct loops *loops)
*** 422,430 ****
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. */
if (latch != ENTRY_BLOCK_PTR
! && dominated_by_p (CDI_DOMINATORS, latch, header))
{
/* Shared headers should be eliminated by now. */
SET_BIT (headers, header->index);
--- 458,470 ----
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.
! If there is no regular path from the header to the
! latch do not consider this latch (not worth the
! problems). */
if (latch != ENTRY_BLOCK_PTR
! && dominated_by_p (CDI_DOMINATORS, latch, header)
! && path_without_edge_flags (header, latch, EDGE_COMPLEX))
{
/* Shared headers should be eliminated by now. */
SET_BIT (headers, header->index);
