In tree-ssa-loop-split.c, split_loop and split_loop_on_cond does two kind of split. split_loop only works for single loop and insert edge at exit when split, while split_loop_on_cond is not limited to single loop and insert edge at latch when split. Both split behavior should consider loop count and probability update. For split_loop, loop split condition is moved in front of loop1 and loop2; But split_loop_on_cond moves the condition between loop1 and loop2, this patch does: 1) profile count proportion for both original loop and copied loop without dropping down the true branch's count; 2) probability update in the two loops and between the two loops.
Regression tested pass, OK for master? Changes diff for split_loop and split_loop_on_cond cases: 1) diff base/loop-split.c.151t.lsplit patched/loop-split.c.152t.lsplit ... <bb 2> [local count: 118111600]: if (beg_5(D) < end_8(D)) goto <bb 14>; [89.00%] else goto <bb 6>; [11.00%] <bb 14> [local count: 105119324]: if (beg2_6(D) < c_9(D)) - goto <bb 15>; [100.00%] + goto <bb 15>; [33.00%] else - goto <bb 16>; [100.00%] + goto <bb 16>; [67.00%] - <bb 15> [local count: 105119324]: + <bb 15> [local count: 34689377]: _25 = beg_5(D) + 1; _26 = end_8(D) - beg_5(D); _27 = beg2_6(D) + _26; _28 = MIN_EXPR <c_9(D), _27>; - <bb 3> [local count: 955630225]: + <bb 3> [local count: 315357973]: # i_16 = PHI <i_11(8), beg_5(D)(15)> # j_17 = PHI <j_12(8), beg2_6(D)(15)> printf ("a: %d %d\n", i_16, j_17); i_11 = i_16 + 1; j_12 = j_17 + 1; if (j_12 < _28) - goto <bb 8>; [89.00%] + goto <bb 8>; [29.37%] else - goto <bb 17>; [11.00%] + goto <bb 17>; [70.63%] - <bb 8> [local count: 850510901]: + <bb 8> [local count: 280668596]: goto <bb 3>; [100.00%] - <bb 16> [local count: 105119324]: + <bb 16> [local count: 70429947]: # i_22 = PHI <beg_5(D)(14), i_29(17)> # j_23 = PHI <beg2_6(D)(14), j_30(17)> <bb 10> [local count: 955630225]: # i_2 = PHI <i_22(16), i_20(13)> # j_1 = PHI <j_23(16), j_21(13)> i_20 = i_2 + 1; j_21 = j_1 + 1; if (end_8(D) > i_20) - goto <bb 13>; [89.00%] + goto <bb 13>; [59.63%] else - goto <bb 9>; [11.00%] + goto <bb 9>; [40.37%] - <bb 13> [local count: 850510901]: + <bb 13> [local count: 569842305]: goto <bb 10>; [100.00%] <bb 17> [local count: 105119324]: # i_29 = PHI <i_11(3)> # j_30 = PHI <j_12(3)> if (end_8(D) > i_29) goto <bb 16>; [80.00%] else goto <bb 9>; [20.00%] <bb 9> [local count: 105119324]: <bb 6> [local count: 118111600]: return 0; } <bb 2> [local count: 118111600]: - if (beg_5(D) < end_8(D)) + _1 = end_6(D) - beg_7(D); + j_9 = _1 + beg2_8(D); + if (end_6(D) > beg_7(D)) goto <bb 14>; [89.00%] else goto <bb 6>; [11.00%] <bb 14> [local count: 105119324]: - if (beg2_6(D) < c_9(D)) - goto <bb 15>; [100.00%] + if (j_9 >= c_11(D)) + goto <bb 15>; [33.00%] else - goto <bb 16>; [100.00%] + goto <bb 16>; [67.00%] - <bb 15> [local count: 105119324]: - _25 = beg_5(D) + 1; - _26 = end_8(D) - beg_5(D); - _27 = beg2_6(D) + _26; - _28 = MIN_EXPR <c_9(D), _27>; - - <bb 3> [local count: 955630225]: - # i_16 = PHI <i_11(8), beg_5(D)(15)> - # j_17 = PHI <j_12(8), beg2_6(D)(15)> - printf ("a: %d %d\n", i_16, j_17); - i_11 = i_16 + 1; - j_12 = j_17 + 1; - if (j_12 < _28) - goto <bb 8>; [89.00%] + <bb 15> [local count: 34689377]: + _27 = end_6(D) + -1; + _28 = beg_7(D) - end_6(D); + _29 = j_9 + _28; + _30 = _29 + 1; + _31 = MAX_EXPR <c_11(D), _30>; + + <bb 3> [local count: 315357973]: + # i_18 = PHI <i_13(8), end_6(D)(15)> + # j_19 = PHI <j_14(8), j_9(15)> + printf ("a: %d %d\n", i_18, j_19); + i_13 = i_18 + -1; + j_14 = j_19 + -1; + if (j_14 >= _31) + goto <bb 8>; [29.37%] else - goto <bb 17>; [11.00%] + goto <bb 17>; [70.63%] - <bb 8> [local count: 850510901]: + <bb 8> [local count: 280668596]: goto <bb 3>; [100.00%] - <bb 16> [local count: 105119324]: - # i_22 = PHI <beg_5(D)(14), i_29(17)> - # j_23 = PHI <beg2_6(D)(14), j_30(17)> + <bb 16> [local count: 70429947]: + # i_24 = PHI <end_6(D)(14), i_32(17)> + # j_25 = PHI <j_9(14), j_33(17)> <bb 10> [local count: 955630225]: - # i_2 = PHI <i_22(16), i_20(13)> - # j_1 = PHI <j_23(16), j_21(13)> - i_20 = i_2 + 1; - j_21 = j_1 + 1; - if (end_8(D) > i_20) + # i_3 = PHI <i_24(16), i_22(13)> + # j_2 = PHI <j_25(16), j_23(13)> + i_22 = i_3 + -1; + j_23 = j_2 + -1; + if (beg_7(D) < i_22) goto <bb 13>; [89.00%] else goto <bb 9>; [11.00%] - <bb 13> [local count: 850510901]: + <bb 13> [local count: 569842305]: goto <bb 10>; [100.00%] <bb 17> [local count: 105119324]: - # i_29 = PHI <i_11(3)> - # j_30 = PHI <j_12(3)> - if (end_8(D) > i_29) + # i_32 = PHI <i_13(3)> + # j_33 = PHI <j_14(3)> + if (beg_7(D) < i_32) goto <bb 16>; [80.00%] else goto <bb 9>; [20.00%] <bb 9> [local count: 105119324]: <bb 6> [local count: 118111600]: return 0; } 2) diff base/loop-cond-split-1.c.151t.lsplit patched/loop-cond-split-1.c.151t.lsplit: ... <bb 2> [local count: 118111600]: if (n_7(D) > 0) goto <bb 4>; [89.00%] else goto <bb 3>; [11.00%] <bb 3> [local count: 118111600]: return; <bb 4> [local count: 105119324]: pretmp_3 = ga; - <bb 5> [local count: 955630225]: + <bb 5> [local count: 315357973]: # i_13 = PHI <i_10(20), 0(4)> # prephitmp_12 = PHI <prephitmp_5(20), pretmp_3(4)> if (prephitmp_12 != 0) goto <bb 6>; [33.00%] else goto <bb 7>; [67.00%] <bb 6> [local count: 315357972]: _2 = do_something (); ga = _2; - <bb 7> [local count: 955630225]: + <bb 7> [local count: 315357973]: # prephitmp_5 = PHI <prephitmp_12(5), _2(6)> i_10 = inc (i_13); if (n_7(D) > i_10) goto <bb 21>; [89.00%] else goto <bb 11>; [11.00%] <bb 11> [local count: 105119324]: goto <bb 3>; [100.00%] - <bb 21> [local count: 850510901]: + <bb 21> [local count: 280668596]: if (prephitmp_12 != 0) - goto <bb 20>; [100.00%] + goto <bb 20>; [33.00%] else - goto <bb 19>; [INV] + goto <bb 19>; [67.00%] - <bb 20> [local count: 850510901]: + <bb 20> [local count: 280668596]: goto <bb 5>; [100.00%] - <bb 19> [count: 0]: + <bb 19> [local count: 70429947]: # i_23 = PHI <i_10(21)> # prephitmp_25 = PHI <prephitmp_5(21)> - <bb 12> [local count: 955630225]: + <bb 12> [local count: 640272252]: # i_15 = PHI <i_23(19), i_22(16)> # prephitmp_16 = PHI <prephitmp_25(19), prephitmp_16(16)> i_22 = inc (i_15); if (n_7(D) > i_22) goto <bb 16>; [89.00%] else goto <bb 11>; [11.00%] - <bb 16> [local count: 850510901]: + <bb 16> [local count: 569842305]: goto <bb 12>; [100.00%] } gcc/ChangeLog: * tree-ssa-loop-split.c (split_loop): Fix incorrect profile_count and probability. (do_split_loop_on_cond): Likewise. --- gcc/tree-ssa-loop-split.c | 85 +++++++++++++++++++++++++++++++++++---- 1 file changed, 77 insertions(+), 8 deletions(-) diff --git a/gcc/tree-ssa-loop-split.c b/gcc/tree-ssa-loop-split.c index 3f6ad046623..33128061aab 100644 --- a/gcc/tree-ssa-loop-split.c +++ b/gcc/tree-ssa-loop-split.c @@ -575,7 +575,10 @@ split_loop (class loop *loop1) stmts2); tree cond = build2 (guard_code, boolean_type_node, guard_init, border); if (!initial_true) - cond = fold_build1 (TRUTH_NOT_EXPR, boolean_type_node, cond); + cond = fold_build1 (TRUTH_NOT_EXPR, boolean_type_node, cond); + + edge true_edge, false_edge; + extract_true_false_edges_from_block (bbs[i], &true_edge, &false_edge); /* Now version the loop, placing loop2 after loop1 connecting them, and fix up SSA form for that. */ @@ -583,11 +586,11 @@ split_loop (class loop *loop1) basic_block cond_bb; class loop *loop2 = loop_version (loop1, cond, &cond_bb, - profile_probability::always (), - profile_probability::always (), - profile_probability::always (), - profile_probability::always (), - true); + true_edge->probability, + true_edge->probability.invert (), + profile_probability::always (), + profile_probability::always (), + true); gcc_assert (loop2); edge new_e = connect_loops (loop1, loop2); @@ -607,6 +610,38 @@ split_loop (class loop *loop1) tree guard_next = PHI_ARG_DEF_FROM_EDGE (phi, loop_latch_edge (loop1)); patch_loop_exit (loop1, guard_stmt, guard_next, newend, initial_true); + update_ssa (TODO_update_ssa); + + /* Proportion first loop's bb counts except those dominated by true + branch to avoid drop 1s down. */ + basic_block *bbs1, *bbs2; + bbs1 = get_loop_body (loop1); + unsigned j; + for (j = 0; j < loop1->num_nodes; j++) + if (bbs1[j] == loop1->latch + || !dominated_by_p (CDI_DOMINATORS, bbs1[j], true_edge->dest)) + bbs1[j]->count + = bbs1[j]->count.apply_probability (true_edge->probability); + free (bbs1); + + /* Fix first loop's exit probability after scaling. */ + edge exit_to_latch1 = single_pred_edge (loop1->latch); + exit_to_latch1->probability = exit_to_latch1->probability.apply_scale ( + true_edge->probability.to_reg_br_prob_base (), REG_BR_PROB_BASE); + single_exit (loop1)->probability + = exit_to_latch1->probability.invert (); + + /* Proportion second loop's bb counts except those dominated by false + branch to avoid drop 1s down. */ + basic_block bbi_copy = get_bb_copy (false_edge->dest); + bbs2 = get_loop_body (loop2); + for (j = 0; j < loop2->num_nodes; j++) + if (bbs2[j] == loop2->latch + || !dominated_by_p (CDI_DOMINATORS, bbs2[j], bbi_copy)) + bbs2[j]->count = bbs2[j]->count.apply_probability ( + true_edge->probability.invert ()); + free (bbs2); + /* Finally patch out the two copies of the condition to be always true/false (or opposite). */ gcond *force_true = as_a<gcond *> (last_stmt (bbs[i])); @@ -1486,8 +1521,8 @@ do_split_loop_on_cond (struct loop *loop1, edge invar_branch) initialize_original_copy_tables (); struct loop *loop2 = loop_version (loop1, boolean_true_node, NULL, - profile_probability::always (), - profile_probability::never (), + invar_branch->probability.invert (), + invar_branch->probability, profile_probability::always (), profile_probability::always (), true); @@ -1535,6 +1570,40 @@ do_split_loop_on_cond (struct loop *loop1, edge invar_branch) between loop1 and loop2. */ connect_loop_phis (loop1, loop2, to_loop2); + update_ssa (TODO_update_ssa); + + edge true_edge, false_edge, skip_edge1, skip_edge2; + extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); + + /* Proportion first loop's bb counts except those dominated by true + branch to avoid drop 1s down. */ + skip_edge1 = true_invar ? false_edge : true_edge; + skip_edge2 = true_invar ? true_edge : false_edge; + basic_block *bbs1, *bbs2; + bbs1 = get_loop_body (loop1); + unsigned j; + for (j = 0; j < loop1->num_nodes; j++) + if (bbs1[j] == loop1->latch + || !dominated_by_p (CDI_DOMINATORS, bbs1[j], skip_edge1->dest)) + bbs1[j]->count + = bbs1[j]->count.apply_probability (skip_edge1->probability); + free (bbs1); + + /* Fix first loop's exit probability after scaling. */ + to_loop1->probability = invar_branch->probability.invert (); + to_loop2->probability = invar_branch->probability; + + /* Proportion second loop's bb counts except those dominated by false + branch to avoid drop 1s down. */ + basic_block bbi_copy = get_bb_copy (skip_edge2->dest); + bbs2 = get_loop_body (loop2); + for (j = 0; j < loop2->num_nodes; j++) + if (bbs2[j] == loop2->latch + || !dominated_by_p (CDI_DOMINATORS, bbs2[j], bbi_copy)) + bbs2[j]->count + = bbs2[j]->count.apply_probability (skip_edge2->probability); + free (bbs2); + free_original_copy_tables (); return true; -- 2.25.1