diff options
Diffstat (limited to 'gcc/cfgloopmanip.cc')
| -rw-r--r-- | gcc/cfgloopmanip.cc | 57 |
1 files changed, 52 insertions, 5 deletions
diff --git a/gcc/cfgloopmanip.cc b/gcc/cfgloopmanip.cc index f56a9b8..5273242 100644 --- a/gcc/cfgloopmanip.cc +++ b/gcc/cfgloopmanip.cc @@ -580,13 +580,47 @@ scale_loop_profile (class loop *loop, profile_probability p, unadjusted_exit_count = exit_edge->count (); scale_loop_frequencies (loop, scale_prob); - if (exit_edge) + if (exit_edge && exit_edge->src->loop_father != loop) + { + fprintf (dump_file, + ";; Loop exit is in inner loop;" + " will leave exit probabilities inconsistent\n"); + } + else if (exit_edge) { profile_count old_exit_count = exit_edge->count (); profile_probability new_probability; if (iteration_bound > 0) - new_probability - = unadjusted_exit_count.probability_in (exit_edge->src->count); + { + /* It may happen that the source basic block of the exit edge is + inside in-loop condition: + + +-> header + | | + | B1 + | / \ + | | B2--exit_edge--> + | \ / + | B3 + +__/ + + If B2 count is smaller than desired exit edge count + the profile was inconsistent with the newly discovered upper bound. + Probablity of edge B1->B2 is too low. We do not attempt to fix + that (as it is hard in general) but we want to avoid dropping + count of edge B2->B3 to zero may confuse later optimizations. */ + if (unadjusted_exit_count.apply_scale (7, 8) > exit_edge->src->count) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, + ";; Source basic block of loop exit count is too small;" + " will leave exit probabilities inconsistent\n"); + exit_edge->probability = exit_edge->probability.guessed (); + return; + } + new_probability + = unadjusted_exit_count.probability_in (exit_edge->src->count); + } else new_probability = profile_probability::always (); set_edge_probability_and_rescale_others (exit_edge, new_probability); @@ -1146,8 +1180,7 @@ duplicate_loop_body_to_header_edge (class loop *loop, edge e, profile_count count_le = latch_edge->count (); profile_count count_out_orig = orig ? orig->count () : count_in - count_le; profile_probability prob_pass_thru = count_le.probability_in (count_in); - profile_probability prob_pass_wont_exit = - (count_le + count_out_orig).probability_in (count_in); + profile_count new_count_le = count_le + count_out_orig; if (orig && orig->probability.initialized_p () && !(orig->probability == profile_probability::always ())) @@ -1167,7 +1200,21 @@ duplicate_loop_body_to_header_edge (class loop *loop, edge e, && dominated_by_p (CDI_DOMINATORS, bbs[i], orig->src)) bitmap_set_bit (bbs_to_scale, i); } + /* Since we will scale up all basic blocks dominated by orig, exits + will become more likely; compensate for that. */ + if (after_exit_den.nonzero_p ()) + { + auto_vec<edge> exits = get_loop_exit_edges (loop); + for (edge ex : exits) + if (ex != orig + && dominated_by_p (CDI_DOMINATORS, ex->src, orig->src)) + new_count_le -= ex->count ().apply_scale (after_exit_num + - after_exit_den, + after_exit_den); + } } + profile_probability prob_pass_wont_exit = + new_count_le.probability_in (count_in); scale_step = XNEWVEC (profile_probability, ndupl); |