/* Control flow graph analysis code for GNU compiler.
- Copyright (C) 1987-2017 Free Software Foundation, Inc.
+ Copyright (C) 1987-2018 Free Software Foundation, Inc.
This file is part of GCC.
basic_block deadend_block = dfs_find_deadend (unvisited_block);
edge e = make_edge (deadend_block, EXIT_BLOCK_PTR_FOR_FN (cfun),
EDGE_FAKE);
- e->count = profile_count::zero ();
e->probability = profile_probability::never ();
dfs.add_bb (deadend_block);
}
basic_block
dfs_find_deadend (basic_block bb)
{
- bitmap visited = BITMAP_ALLOC (NULL);
+ auto_bitmap visited;
+ basic_block next = bb;
for (;;)
{
- if (EDGE_COUNT (bb->succs) == 0
- || ! bitmap_set_bit (visited, bb->index))
- {
- BITMAP_FREE (visited);
- return bb;
- }
+ if (EDGE_COUNT (next->succs) == 0)
+ return next;
+
+ if (! bitmap_set_bit (visited, next->index))
+ return bb;
+ bb = next;
/* If we are in an analyzed cycle make sure to try exiting it.
Note this is a heuristic only and expected to work when loop
fixup is needed as well. */
if (! bb->loop_father
|| ! loop_outer (bb->loop_father))
- bb = EDGE_SUCC (bb, 0)->dest;
+ next = EDGE_SUCC (bb, 0)->dest;
else
{
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
if (loop_exit_edge_p (bb->loop_father, e))
break;
- bb = e ? e->dest : EDGE_SUCC (bb, 0)->dest;
+ next = e ? e->dest : EDGE_SUCC (bb, 0)->dest;
}
}
#undef MARK_VISITED
#undef VISITED_P
}
+
+/* Ignoring loop backedges, if BB has precisely one incoming edge then
+ return that edge. Otherwise return NULL.
+
+ When IGNORE_NOT_EXECUTABLE is true, also ignore edges that are not marked
+ as executable. */
+
+edge
+single_pred_edge_ignoring_loop_edges (basic_block bb,
+ bool ignore_not_executable)
+{
+ edge retval = NULL;
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ /* A loop back edge can be identified by the destination of
+ the edge dominating the source of the edge. */
+ if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
+ continue;
+
+ /* We can safely ignore edges that are not executable. */
+ if (ignore_not_executable
+ && (e->flags & EDGE_EXECUTABLE) == 0)
+ continue;
+
+ /* If we have already seen a non-loop edge, then we must have
+ multiple incoming non-loop edges and thus we return NULL. */
+ if (retval)
+ return NULL;
+
+ /* This is the first non-loop incoming edge we have found. Record
+ it. */
+ retval = e;
+ }
+
+ return retval;
+}