On Sun, Oct 30, 2016 at 8:10 PM, Segher Boessenkool wrote:
> This patch solves this problem by simply running the duplicate_computed_gotos
> pass again, as long as it does any work. The patch looks much bigger than
> it is, because I factored out two routines to simplify the control flow.
It's made the patch a bit difficult to read. Condensing it a bit...
> + for (;;)
> {
> + if (n_basic_blocks_for_fn (fun) <= NUM_FIXED_BLOCKS + 1)
> + return 0;
This test should not be needed in the loop. This pass can never
collapse the function to a single basic block.
> + clear_bb_flags ();
> + cfg_layout_initialize (0);
See comment below...
> + basic_block bb;
> + FOR_EACH_BB_FN (bb, fun)
> + {
> + /* Build the reorder chain for the original order of blocks. */
> + if (bb->next_bb != EXIT_BLOCK_PTR_FOR_FN (fun))
> + bb->aux = bb->next_bb;
> + }
>
> + duplicate_computed_gotos_find_candidates (fun, candidates, max_size);
>
> + bool changed = false;
> + if (!bitmap_empty_p (candidates))
> + changed = duplicate_computed_gotos_do_duplicate (fun, candidates);
>
> + if (changed)
> + fixup_partitions ();
> +
> + cfg_layout_finalize ();
I don't think you have to go into/out-of cfglayout mode for each iteration.
> /* Merge the duplicated blocks into predecessors, when possible. */
> + if (changed)
> + cleanup_cfg (0);
> + else
> + break;
> }
Maybe a gcc_assert that the loop doesn't iterate more often than num_edges?
Ciao!
Steven
