-/* Return true, iff LOOP is if-convertible.
- LOOP is if-convertible if,
- - It is innermost.
- - It has two or more basic blocks.
- - It has only one exit.
- - Loop header is not the exit edge.
- - If its basic blocks and phi nodes are if convertible. See above for
- more info.
- FOR_VECTORIZER enables vectorizer specific checks. For example, support
- for vector conditions, data dependency checks etc.. (Not implemented yet). */
+/* Return true when all predecessor blocks of BB are visited. The
+ VISITED bitmap keeps track of the visited blocks. */
+
+static bool
+pred_blocks_visited_p (basic_block bb, bitmap *visited)
+{
+ edge e;
+ edge_iterator ei;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (!bitmap_bit_p (*visited, e->src->index))
+ return false;
+
+ return true;
+}
+
+/* Get body of a LOOP in suitable order for if-conversion. It is
+ caller's responsibility to deallocate basic block list.
+ If-conversion suitable order is, breadth first sort (BFS) order
+ with an additional constraint: select a block only if all its
+ predecessors are already selected. */
+
+static basic_block *
+get_loop_body_in_if_conv_order (const struct loop *loop)
+{
+ basic_block *blocks, *blocks_in_bfs_order;
+ basic_block bb;
+ bitmap visited;
+ unsigned int index = 0;
+ unsigned int visited_count = 0;
+
+ gcc_assert (loop->num_nodes);
+ gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+
+ blocks = XCNEWVEC (basic_block, loop->num_nodes);
+ visited = BITMAP_ALLOC (NULL);
+
+ blocks_in_bfs_order = get_loop_body_in_bfs_order (loop);
+
+ index = 0;
+ while (index < loop->num_nodes)
+ {
+ bb = blocks_in_bfs_order [index];
+
+ if (bb->flags & BB_IRREDUCIBLE_LOOP)
+ {
+ free (blocks_in_bfs_order);
+ BITMAP_FREE (visited);
+ free (blocks);
+ return NULL;
+ }
+
+ if (!bitmap_bit_p (visited, bb->index))
+ {
+ if (pred_blocks_visited_p (bb, &visited)
+ || bb == loop->header)
+ {
+ /* This block is now visited. */
+ bitmap_set_bit (visited, bb->index);
+ blocks[visited_count++] = bb;
+ }
+ }
+
+ index++;
+
+ if (index == loop->num_nodes
+ && visited_count != loop->num_nodes)
+ /* Not done yet. */
+ index = 0;
+ }
+ free (blocks_in_bfs_order);
+ BITMAP_FREE (visited);
+ return blocks;
+}
+
+/* Return true when LOOP is if-convertible.
+ LOOP is if-convertible if:
+ - it is innermost,
+ - it has two or more basic blocks,
+ - it has only one exit,
+ - loop header is not the exit edge,
+ - if its basic blocks and phi nodes are if convertible. */
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