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Improve var-tracking dataflow iteration order
This builds upon the rev_post_order_and_mark_dfs_back_seme improvements and makes vt_find_locations iterate over the dataflow problems for each toplevel SCC separately, improving memory locality and avoiding to process nodes after the SCC before the SCC itself stabilized. On the asan_interceptors.cc testcase this for example reduces the number of visited blocks from 3751 to 2867. For stage3-gcc this reduces the number of visited blocks by ~4%. 2020-07-28 Richard Biener <rguenther@suse.de> PR debug/78288 * var-tracking.c (vt_find_locations): Use rev_post_order_and_mark_dfs_back_seme and separately iterate over toplevel SCCs.
This commit is contained in:
Richard Biener
parent
3e61a20563
commit
1212cfad09
@ -7084,164 +7084,191 @@ vt_find_locations (void)
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so that the data-flow runs faster. */
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rc_order = XNEWVEC (int, n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS);
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bb_order = XNEWVEC (int, last_basic_block_for_fn (cfun));
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pre_and_rev_post_order_compute (NULL, rc_order, false);
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for (i = 0; i < n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS; i++)
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auto_bitmap exit_bbs;
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bitmap_set_bit (exit_bbs, EXIT_BLOCK);
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auto_vec<std::pair<int, int> > toplevel_scc_extents;
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int n = rev_post_order_and_mark_dfs_back_seme
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(cfun, single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun)), exit_bbs, true,
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rc_order, &toplevel_scc_extents);
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for (i = 0; i < n; i++)
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bb_order[rc_order[i]] = i;
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free (rc_order);
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in_worklist = sbitmap_alloc (last_basic_block_for_fn (cfun));
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in_pending = sbitmap_alloc (last_basic_block_for_fn (cfun));
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bitmap_clear (in_worklist);
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FOR_EACH_BB_FN (bb, cfun)
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pending->insert (bb_order[bb->index], bb);
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bitmap_ones (in_pending);
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while (success && !pending->empty ())
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/* We're performing the dataflow iteration independently over the
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toplevel SCCs plus leading non-cyclic entry blocks and separately
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over the tail. That ensures best memory locality and the least
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number of visited blocks. */
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unsigned extent = 0;
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int curr_start = -1;
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int curr_end = -1;
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do
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{
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std::swap (worklist, pending);
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std::swap (in_worklist, in_pending);
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curr_start = curr_end + 1;
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if (toplevel_scc_extents.length () <= extent)
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curr_end = n - 1;
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else
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curr_end = toplevel_scc_extents[extent++].second;
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while (!worklist->empty ())
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for (int i = curr_start; i <= curr_end; ++i)
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{
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bool changed;
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edge_iterator ei;
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int oldinsz, oldoutsz;
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pending->insert (i, BASIC_BLOCK_FOR_FN (cfun, rc_order[i]));
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bitmap_set_bit (in_pending, rc_order[i]);
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}
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bb = worklist->extract_min ();
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bitmap_clear_bit (in_worklist, bb->index);
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while (success && !pending->empty ())
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{
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std::swap (worklist, pending);
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std::swap (in_worklist, in_pending);
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if (VTI (bb)->in.vars)
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while (!worklist->empty ())
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{
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htabsz -= (shared_hash_htab (VTI (bb)->in.vars)->size ()
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+ shared_hash_htab (VTI (bb)->out.vars)->size ());
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oldinsz = shared_hash_htab (VTI (bb)->in.vars)->elements ();
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oldoutsz = shared_hash_htab (VTI (bb)->out.vars)->elements ();
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}
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else
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oldinsz = oldoutsz = 0;
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bool changed;
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edge_iterator ei;
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int oldinsz, oldoutsz;
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if (MAY_HAVE_DEBUG_BIND_INSNS)
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{
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dataflow_set *in = &VTI (bb)->in, *first_out = NULL;
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bool first = true, adjust = false;
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bb = worklist->extract_min ();
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bitmap_clear_bit (in_worklist, bb->index);
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/* Calculate the IN set as the intersection of
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predecessor OUT sets. */
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dataflow_set_clear (in);
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dst_can_be_shared = true;
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FOR_EACH_EDGE (e, ei, bb->preds)
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if (!VTI (e->src)->flooded)
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gcc_assert (bb_order[bb->index]
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<= bb_order[e->src->index]);
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else if (first)
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{
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dataflow_set_copy (in, &VTI (e->src)->out);
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first_out = &VTI (e->src)->out;
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first = false;
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}
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else
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{
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dataflow_set_merge (in, &VTI (e->src)->out);
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adjust = true;
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}
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if (adjust)
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if (VTI (bb)->in.vars)
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{
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dataflow_post_merge_adjust (in, &VTI (bb)->permp);
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if (flag_checking)
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/* Merge and merge_adjust should keep entries in
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canonical order. */
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shared_hash_htab (in->vars)
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->traverse <dataflow_set *,
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canonicalize_loc_order_check> (in);
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if (dst_can_be_shared)
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{
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shared_hash_destroy (in->vars);
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in->vars = shared_hash_copy (first_out->vars);
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}
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htabsz -= (shared_hash_htab (VTI (bb)->in.vars)->size ()
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+ shared_hash_htab (VTI (bb)->out.vars)->size ());
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oldinsz = shared_hash_htab (VTI (bb)->in.vars)->elements ();
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oldoutsz = shared_hash_htab (VTI (bb)->out.vars)->elements ();
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}
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VTI (bb)->flooded = true;
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}
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else
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{
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/* Calculate the IN set as union of predecessor OUT sets. */
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dataflow_set_clear (&VTI (bb)->in);
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FOR_EACH_EDGE (e, ei, bb->preds)
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dataflow_set_union (&VTI (bb)->in, &VTI (e->src)->out);
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}
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changed = compute_bb_dataflow (bb);
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n_blocks_processed++;
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htabsz += (shared_hash_htab (VTI (bb)->in.vars)->size ()
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+ shared_hash_htab (VTI (bb)->out.vars)->size ());
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if (htabmax && htabsz > htabmax)
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{
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if (MAY_HAVE_DEBUG_BIND_INSNS)
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inform (DECL_SOURCE_LOCATION (cfun->decl),
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"variable tracking size limit exceeded with "
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"%<-fvar-tracking-assignments%>, retrying without");
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else
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inform (DECL_SOURCE_LOCATION (cfun->decl),
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"variable tracking size limit exceeded");
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success = false;
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break;
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}
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oldinsz = oldoutsz = 0;
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if (changed)
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{
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FOR_EACH_EDGE (e, ei, bb->succs)
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if (MAY_HAVE_DEBUG_BIND_INSNS)
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{
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if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
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continue;
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dataflow_set *in = &VTI (bb)->in, *first_out = NULL;
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bool first = true, adjust = false;
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/* Iterate to an earlier block in RPO in the next
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round, iterate to the same block immediately. */
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if (bb_order[e->dest->index] < bb_order[bb->index])
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/* Calculate the IN set as the intersection of
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predecessor OUT sets. */
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dataflow_set_clear (in);
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dst_can_be_shared = true;
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FOR_EACH_EDGE (e, ei, bb->preds)
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if (!VTI (e->src)->flooded)
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gcc_assert (bb_order[bb->index]
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<= bb_order[e->src->index]);
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else if (first)
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{
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dataflow_set_copy (in, &VTI (e->src)->out);
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first_out = &VTI (e->src)->out;
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first = false;
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}
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else
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{
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dataflow_set_merge (in, &VTI (e->src)->out);
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adjust = true;
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}
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if (adjust)
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{
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if (!bitmap_bit_p (in_pending, e->dest->index))
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dataflow_post_merge_adjust (in, &VTI (bb)->permp);
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if (flag_checking)
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/* Merge and merge_adjust should keep entries in
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canonical order. */
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shared_hash_htab (in->vars)
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->traverse <dataflow_set *,
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canonicalize_loc_order_check> (in);
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if (dst_can_be_shared)
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{
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/* Send E->DEST to next round. */
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bitmap_set_bit (in_pending, e->dest->index);
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pending->insert (bb_order[e->dest->index],
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e->dest);
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shared_hash_destroy (in->vars);
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in->vars = shared_hash_copy (first_out->vars);
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}
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}
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else if (!bitmap_bit_p (in_worklist, e->dest->index))
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VTI (bb)->flooded = true;
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}
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else
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{
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/* Calculate the IN set as union of predecessor OUT sets. */
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dataflow_set_clear (&VTI (bb)->in);
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FOR_EACH_EDGE (e, ei, bb->preds)
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dataflow_set_union (&VTI (bb)->in, &VTI (e->src)->out);
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}
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changed = compute_bb_dataflow (bb);
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n_blocks_processed++;
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htabsz += (shared_hash_htab (VTI (bb)->in.vars)->size ()
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+ shared_hash_htab (VTI (bb)->out.vars)->size ());
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if (htabmax && htabsz > htabmax)
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{
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if (MAY_HAVE_DEBUG_BIND_INSNS)
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inform (DECL_SOURCE_LOCATION (cfun->decl),
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"variable tracking size limit exceeded with "
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"%<-fvar-tracking-assignments%>, retrying without");
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else
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inform (DECL_SOURCE_LOCATION (cfun->decl),
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"variable tracking size limit exceeded");
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success = false;
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break;
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}
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if (changed)
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{
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FOR_EACH_EDGE (e, ei, bb->succs)
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{
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/* Add E->DEST to current round. */
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bitmap_set_bit (in_worklist, e->dest->index);
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worklist->insert (bb_order[e->dest->index],
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e->dest);
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if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
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continue;
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/* Iterate to an earlier block in RPO in the next
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round, iterate to the same block immediately. */
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if (bb_order[e->dest->index] < bb_order[bb->index])
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{
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gcc_assert (bb_order[e->dest->index] >= curr_start);
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if (!bitmap_bit_p (in_pending, e->dest->index))
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{
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/* Send E->DEST to next round. */
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bitmap_set_bit (in_pending, e->dest->index);
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pending->insert (bb_order[e->dest->index],
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e->dest);
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}
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}
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else if (bb_order[e->dest->index] <= curr_end
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&& !bitmap_bit_p (in_worklist, e->dest->index))
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{
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/* Add E->DEST to current round or delay
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processing if it is in the next SCC. */
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bitmap_set_bit (in_worklist, e->dest->index);
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worklist->insert (bb_order[e->dest->index],
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e->dest);
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}
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}
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}
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}
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if (dump_file)
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fprintf (dump_file,
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"BB %i: in %i (was %i), out %i (was %i), rem %i + %i, tsz %i\n",
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bb->index,
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(int)shared_hash_htab (VTI (bb)->in.vars)->size (),
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oldinsz,
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(int)shared_hash_htab (VTI (bb)->out.vars)->size (),
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oldoutsz,
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(int)worklist->nodes (), (int)pending->nodes (), htabsz);
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if (dump_file)
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fprintf (dump_file,
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"BB %i: in %i (was %i), out %i (was %i), rem %i + %i, "
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"tsz %i\n", bb->index,
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(int)shared_hash_htab (VTI (bb)->in.vars)->size (),
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oldinsz,
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(int)shared_hash_htab (VTI (bb)->out.vars)->size (),
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oldoutsz,
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(int)worklist->nodes (), (int)pending->nodes (),
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htabsz);
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if (dump_file && (dump_flags & TDF_DETAILS))
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{
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fprintf (dump_file, "BB %i IN:\n", bb->index);
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dump_dataflow_set (&VTI (bb)->in);
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fprintf (dump_file, "BB %i OUT:\n", bb->index);
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dump_dataflow_set (&VTI (bb)->out);
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if (dump_file && (dump_flags & TDF_DETAILS))
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{
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fprintf (dump_file, "BB %i IN:\n", bb->index);
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dump_dataflow_set (&VTI (bb)->in);
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fprintf (dump_file, "BB %i OUT:\n", bb->index);
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dump_dataflow_set (&VTI (bb)->out);
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}
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}
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}
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}
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while (curr_end != n - 1);
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statistics_counter_event (cfun, "compute_bb_dataflow times",
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n_blocks_processed);
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@ -7250,6 +7277,7 @@ vt_find_locations (void)
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FOR_EACH_BB_FN (bb, cfun)
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gcc_assert (VTI (bb)->flooded);
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free (rc_order);
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free (bb_order);
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delete worklist;
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delete pending;
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