diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 07bcc26b5b6..da6c6409700 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,13 @@ +2016-11-28 Segher Boessenkool + + * shrink-wrap.c (init_separate_shrink_wrap): Do not clear + head_components and tail_components. + (spread_components): New algorithm. + (emit_common_tails_for_components): Clear head_components and + tail_components. + (insert_prologue_epilogue_for_components): Write extra output to the + dump file for sibcalls and abnormal exits. + 2016-11-28 Segher Boessenkool PR rtl-optimization/78342 diff --git a/gcc/shrink-wrap.c b/gcc/shrink-wrap.c index 8803200fbe0..59feca15aea 100644 --- a/gcc/shrink-wrap.c +++ b/gcc/shrink-wrap.c @@ -1131,8 +1131,6 @@ init_separate_shrink_wrap (sbitmap components) SW (bb)->head_components = sbitmap_alloc (SBITMAP_SIZE (components)); SW (bb)->tail_components = sbitmap_alloc (SBITMAP_SIZE (components)); bitmap_clear (SW (bb)->has_components); - bitmap_clear (SW (bb)->head_components); - bitmap_clear (SW (bb)->tail_components); } } @@ -1253,48 +1251,151 @@ place_prologue_for_one_component (unsigned int which, basic_block head) } } -/* Mark HAS_COMPONENTS for every block dominated by at least one block with - HAS_COMPONENTS set for the respective components, starting at HEAD. */ +/* Set HAS_COMPONENTS in every block to the maximum it can be set to without + setting it on any path from entry to exit where it was not already set + somewhere (or, for blocks that have no path to the exit, consider only + paths from the entry to the block itself). */ static void -spread_components (basic_block head) +spread_components (sbitmap components) { - basic_block bb = head; - bool first_visit = true; - /* This keeps a tally of all components active. */ - sbitmap components = SW (head)->has_components; + basic_block entry_block = ENTRY_BLOCK_PTR_FOR_FN (cfun); + basic_block exit_block = EXIT_BLOCK_PTR_FOR_FN (cfun); - for (;;) + /* A stack of all blocks left to consider, and a bitmap of all blocks + on that stack. */ + vec todo; + todo.create (n_basic_blocks_for_fn (cfun)); + bitmap seen = BITMAP_ALLOC (NULL); + + sbitmap old = sbitmap_alloc (SBITMAP_SIZE (components)); + + /* Find for every block the components that are *not* needed on some path + from the entry to that block. Do this with a flood fill from the entry + block. Every block can be visited at most as often as the number of + components (plus one), and usually much less often. */ + + if (dump_file) + fprintf (dump_file, "Spreading down...\n"); + + basic_block bb; + FOR_ALL_BB_FN (bb, cfun) + bitmap_clear (SW (bb)->head_components); + + bitmap_copy (SW (entry_block)->head_components, components); + + edge e; + edge_iterator ei; + + todo.quick_push (single_succ (entry_block)); + bitmap_set_bit (seen, single_succ (entry_block)->index); + while (!todo.is_empty ()) { - if (first_visit) - { - bitmap_ior (SW (bb)->has_components, SW (bb)->has_components, - components); + bb = todo.pop (); - if (first_dom_son (CDI_DOMINATORS, bb)) - { - components = SW (bb)->has_components; - bb = first_dom_son (CDI_DOMINATORS, bb); - continue; - } - } + bitmap_copy (old, SW (bb)->head_components); - components = SW (bb)->has_components; + FOR_EACH_EDGE (e, ei, bb->preds) + bitmap_ior (SW (bb)->head_components, SW (bb)->head_components, + SW (e->src)->head_components); - if (next_dom_son (CDI_DOMINATORS, bb)) + bitmap_and_compl (SW (bb)->head_components, SW (bb)->head_components, + SW (bb)->has_components); + + if (!bitmap_equal_p (old, SW (bb)->head_components)) + FOR_EACH_EDGE (e, ei, bb->succs) + if (bitmap_set_bit (seen, e->dest->index)) + todo.quick_push (e->dest); + + bitmap_clear_bit (seen, bb->index); + } + + /* Find for every block the components that are *not* needed on some reverse + path from the exit to that block. */ + + if (dump_file) + fprintf (dump_file, "Spreading up...\n"); + + /* First, mark all blocks not reachable from the exit block as not needing + any component on any path to the exit. Mark everything, and then clear + again by a flood fill. */ + + FOR_ALL_BB_FN (bb, cfun) + bitmap_copy (SW (bb)->tail_components, components); + + FOR_EACH_EDGE (e, ei, exit_block->preds) + { + todo.quick_push (e->src); + bitmap_set_bit (seen, e->src->index); + } + + while (!todo.is_empty ()) + { + bb = todo.pop (); + + if (!bitmap_empty_p (SW (bb)->tail_components)) + FOR_EACH_EDGE (e, ei, bb->preds) + if (bitmap_set_bit (seen, e->src->index)) + todo.quick_push (e->src); + + bitmap_clear (SW (bb)->tail_components); + + bitmap_clear_bit (seen, bb->index); + } + + /* And then, flood fill backwards to find for every block the components + not needed on some path to the exit. */ + + bitmap_copy (SW (exit_block)->tail_components, components); + + FOR_EACH_EDGE (e, ei, exit_block->preds) + { + todo.quick_push (e->src); + bitmap_set_bit (seen, e->src->index); + } + + while (!todo.is_empty ()) + { + bb = todo.pop (); + + bitmap_copy (old, SW (bb)->tail_components); + + FOR_EACH_EDGE (e, ei, bb->succs) + bitmap_ior (SW (bb)->tail_components, SW (bb)->tail_components, + SW (e->dest)->tail_components); + + bitmap_and_compl (SW (bb)->tail_components, SW (bb)->tail_components, + SW (bb)->has_components); + + if (!bitmap_equal_p (old, SW (bb)->tail_components)) + FOR_EACH_EDGE (e, ei, bb->preds) + if (bitmap_set_bit (seen, e->src->index)) + todo.quick_push (e->src); + + bitmap_clear_bit (seen, bb->index); + } + + /* Finally, mark everything not not needed both forwards and backwards. */ + + FOR_EACH_BB_FN (bb, cfun) + { + bitmap_and (SW (bb)->head_components, SW (bb)->head_components, + SW (bb)->tail_components); + bitmap_and_compl (SW (bb)->has_components, components, + SW (bb)->head_components); + } + + FOR_ALL_BB_FN (bb, cfun) + { + if (dump_file) { - bb = next_dom_son (CDI_DOMINATORS, bb); - basic_block parent = get_immediate_dominator (CDI_DOMINATORS, bb); - components = SW (parent)->has_components; - first_visit = true; - } - else - { - if (bb == head) - return; - bb = get_immediate_dominator (CDI_DOMINATORS, bb); - first_visit = false; + fprintf (dump_file, "bb %d components:", bb->index); + dump_components ("has", SW (bb)->has_components); + fprintf (dump_file, "\n"); } } + + sbitmap_free (old); + BITMAP_FREE (seen); } /* If we cannot handle placing some component's prologues or epilogues where @@ -1384,6 +1485,9 @@ emit_common_heads_for_components (sbitmap components) sbitmap tmp = sbitmap_alloc (SBITMAP_SIZE (components)); basic_block bb; + FOR_ALL_BB_FN (bb, cfun) + bitmap_clear (SW (bb)->head_components); + FOR_EACH_BB_FN (bb, cfun) { /* Find which prologue resp. epilogue components are needed for all @@ -1470,6 +1574,9 @@ emit_common_tails_for_components (sbitmap components) sbitmap tmp = sbitmap_alloc (SBITMAP_SIZE (components)); basic_block bb; + FOR_ALL_BB_FN (bb, cfun) + bitmap_clear (SW (bb)->tail_components); + FOR_EACH_BB_FN (bb, cfun) { /* Find which prologue resp. epilogue components are needed for all @@ -1608,6 +1715,10 @@ insert_prologue_epilogue_for_components (sbitmap components) e->dest->index); dump_components ("epi", epi); dump_components ("pro", pro); + if (e->flags & EDGE_SIBCALL) + fprintf (dump_file, " (SIBCALL)"); + else if (e->flags & EDGE_ABNORMAL) + fprintf (dump_file, " (ABNORMAL)"); fprintf (dump_file, "\n"); } @@ -1702,7 +1813,7 @@ try_shrink_wrapping_separate (basic_block first_bb) EXECUTE_IF_SET_IN_BITMAP (components, 0, j, sbi) place_prologue_for_one_component (j, first_bb); - spread_components (first_bb); + spread_components (components); disqualify_problematic_components (components);