diff options
Diffstat (limited to 'gcc/cfgloop.c')
| -rw-r--r-- | gcc/cfgloop.c | 70 |
1 files changed, 50 insertions, 20 deletions
diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c index 83a5262..e7cb78a 100644 --- a/gcc/cfgloop.c +++ b/gcc/cfgloop.c @@ -388,6 +388,33 @@ 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 @@ -482,29 +509,10 @@ 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); - - /* 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; - } - } + loop->latch = find_single_latch (loop); } return loops; @@ -1434,6 +1442,28 @@ 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)) { |