diff options
author | Martin Liska <mliska@suse.cz> | 2018-06-20 10:52:12 +0200 |
---|---|---|
committer | Martin Liska <marxin@gcc.gnu.org> | 2018-06-20 08:52:12 +0000 |
commit | dc223ad48971b2d2b1e4bcfbbb47a96354e3d2ea (patch) | |
tree | 612bcb0ce9171f466c03a6f6a569e73120b4fcd2 /gcc/tree-switch-conversion.c | |
parent | 789410e4824b60f423f7855d68f234e02f9300fb (diff) |
Switch other switch expansion methods into classes.
2018-06-20 Martin Liska <mliska@suse.cz>
* tree-switch-conversion.c (switch_conversion::collect):
Record m_uniq property.
(switch_conversion::expand): Bail out for special conditions.
(group_cluster::~group_cluster): New.
(group_cluster::group_cluster): Likewise.
(group_cluster::dump): Likewise.
(jump_table_cluster::emit): New.
(switch_decision_tree::fix_phi_operands_for_edges): New.
(struct case_node): Remove struct.
(jump_table_cluster::can_be_handled): New.
(case_values_threshold): Moved to header.
(reset_out_edges_aux): Likewise.
(jump_table_cluster::is_beneficial): New.
(bit_test_cluster::can_be_handled): Likewise.
(add_case_node): Remove.
(bit_test_cluster::is_beneficial): New.
(case_bit_test::cmp): New.
(bit_test_cluster::emit): New.
(expand_switch_as_decision_tree_p): Remove.
(bit_test_cluster::hoist_edge_and_branch_if_true): New.
(fix_phi_operands_for_edge): Likewise.
(switch_decision_tree::analyze_switch_statement): New.
(compute_cases_per_edge): Move ...
(switch_decision_tree::compute_cases_per_edge): ... here.
(try_switch_expansion): Likewise.
(switch_decision_tree::try_switch_expansion): Likewise.
(record_phi_operand_mapping): Likewise.
(switch_decision_tree::record_phi_operand_mapping): Likewise.
(emit_case_decision_tree): Likewise.
(switch_decision_tree::emit): Likewise.
(balance_case_nodes): Likewise.
(switch_decision_tree::balance_case_nodes): Likewise.
(dump_case_nodes): Likewise.
(switch_decision_tree::dump_case_nodes): Likewise.
(emit_jump): Likewise.
(switch_decision_tree::emit_jump): Likewise.
(emit_cmp_and_jump_insns): Likewise.
(switch_decision_tree::emit_cmp_and_jump_insns): Likewise.
(emit_case_nodes): Likewise.
(switch_decision_tree::emit_case_nodes): Likewise.
(conditional_probability): Remove.
* tree-switch-conversion.h (enum cluster_type): New.
(PRINT_CASE): New.
(struct cluster): Likewise.
(cluster::cluster): Likewise.
(struct simple_cluster): Likewise.
(simple_cluster::simple_cluster): Likewise.
(struct group_cluster): Likewise.
(struct jump_table_cluster): Likewise.
(struct bit_test_cluster): Likewise.
(struct min_cluster_item): Likewise.
(struct case_tree_node): Likewise.
(case_tree_node::case_tree_node): Likewise.
(jump_table_cluster::case_values_threshold): Likewise.
(struct case_bit_test): Likewise.
(struct switch_decision_tree): Likewise.
(struct switch_conversion): Likewise.
(switch_decision_tree::reset_out_edges_aux): Likewise.
2018-06-20 Martin Liska <mliska@suse.cz>
* gcc.dg/tree-ssa/vrp104.c: Grep just for GIMPLE IL.
From-SVN: r261793
Diffstat (limited to 'gcc/tree-switch-conversion.c')
-rw-r--r-- | gcc/tree-switch-conversion.c | 1376 |
1 files changed, 848 insertions, 528 deletions
diff --git a/gcc/tree-switch-conversion.c b/gcc/tree-switch-conversion.c index e8b44bdd2d8..1260ba2e145 100644 --- a/gcc/tree-switch-conversion.c +++ b/gcc/tree-switch-conversion.c @@ -179,6 +179,11 @@ switch_conversion::collect (gswitch *swtch) && ! tree_int_cst_equal (CASE_LOW (elt), CASE_HIGH (elt))) m_count++; } + + /* Get the number of unique non-default targets out of the GIMPLE_SWITCH + block. Assume a CFG cleanup would have already removed degenerate + switch statements, this allows us to just use EDGE_COUNT. */ + m_uniq = EDGE_COUNT (gimple_bb (swtch)->succs) - 1; } /* Checks whether the range given by individual case statements of the switch @@ -935,6 +940,22 @@ switch_conversion::expand (gswitch *swtch) /* A switch on a constant should have been optimized in tree-cfg-cleanup. */ gcc_checking_assert (!TREE_CONSTANT (m_index_expr)); + /* Prefer bit test if possible. */ + if (tree_fits_uhwi_p (m_range_size) + && bit_test_cluster::can_be_handled (tree_to_uhwi (m_range_size), m_uniq) + && bit_test_cluster::is_beneficial (m_count, m_uniq)) + { + m_reason = "expanding as bit test is preferable"; + return; + } + + if (m_uniq <= 2) + { + /* This will be expanded as a decision tree . */ + m_reason = "expanding as jumps is preferable"; + return; + } + /* If there is no common successor, we cannot do the transformation. */ if (!m_final_bb) { @@ -985,157 +1006,443 @@ switch_conversion::~switch_conversion () XDELETEVEC (m_default_values); } -/* The main function of the pass scans statements for switches and invokes - process_switch on them. */ +/* Constructor. */ -namespace { +group_cluster::group_cluster (vec<cluster *> &clusters, + unsigned start, unsigned end) +{ + gcc_checking_assert (end - start + 1 >= 1); + m_prob = profile_probability::never (); + m_cases.create (end - start + 1); + for (unsigned i = start; i <= end; i++) + { + m_cases.quick_push (static_cast<simple_cluster *> (clusters[i])); + m_prob += clusters[i]->m_prob; + } + m_subtree_prob = m_prob; +} -const pass_data pass_data_convert_switch = +/* Destructor. */ + +group_cluster::~group_cluster () { - GIMPLE_PASS, /* type */ - "switchconv", /* name */ - OPTGROUP_NONE, /* optinfo_flags */ - TV_TREE_SWITCH_CONVERSION, /* tv_id */ - ( PROP_cfg | PROP_ssa ), /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - 0, /* todo_flags_start */ - TODO_update_ssa, /* todo_flags_finish */ -}; + for (unsigned i = 0; i < m_cases.length (); i++) + delete m_cases[i]; -class pass_convert_switch : public gimple_opt_pass + m_cases.release (); +} + +/* Dump content of a cluster. */ + +void +group_cluster::dump (FILE *f, bool details) { -public: - pass_convert_switch (gcc::context *ctxt) - : gimple_opt_pass (pass_data_convert_switch, ctxt) - {} + unsigned total_values = 0; + for (unsigned i = 0; i < m_cases.length (); i++) + total_values += m_cases[i]->get_range (m_cases[i]->get_low (), + m_cases[i]->get_high ()); - /* opt_pass methods: */ - virtual bool gate (function *) { return flag_tree_switch_conversion != 0; } - virtual unsigned int execute (function *); + unsigned comparison_count = 0; + for (unsigned i = 0; i < m_cases.length (); i++) + { + simple_cluster *sc = static_cast<simple_cluster *> (m_cases[i]); + comparison_count += sc->m_range_p ? 2 : 1; + } -}; // class pass_convert_switch + unsigned HOST_WIDE_INT range = get_range (get_low (), get_high ()); + fprintf (f, "%s", get_type () == JUMP_TABLE ? "JT" : "BT"); -unsigned int -pass_convert_switch::execute (function *fun) + if (details) + fprintf (f, "(values:%d comparisons:%d range:" HOST_WIDE_INT_PRINT_DEC + " density: %.2f%%)", total_values, comparison_count, range, + 100.0f * comparison_count / range); + + fprintf (f, ":"); + PRINT_CASE (f, get_low ()); + fprintf (f, "-"); + PRINT_CASE (f, get_high ()); + fprintf (f, " "); +} + +/* Emit GIMPLE code to handle the cluster. */ + +void +jump_table_cluster::emit (tree index_expr, tree, + tree default_label_expr, basic_block default_bb) { - basic_block bb; - bool cfg_altered = false; + /* For jump table we just emit a new gswitch statement that will + be latter lowered to jump table. */ + auto_vec <tree> labels; + labels.create (m_cases.length ()); - FOR_EACH_BB_FN (bb, fun) - { - gimple *stmt = last_stmt (bb); - if (stmt && gimple_code (stmt) == GIMPLE_SWITCH) - { - if (dump_file) - { - expanded_location loc = expand_location (gimple_location (stmt)); + make_edge (m_case_bb, default_bb, 0); + for (unsigned i = 0; i < m_cases.length (); i++) + { + labels.quick_push (unshare_expr (m_cases[i]->m_case_label_expr)); + make_edge (m_case_bb, m_cases[i]->m_case_bb, 0); + } - fprintf (dump_file, "beginning to process the following " - "SWITCH statement (%s:%d) : ------- \n", - loc.file, loc.line); - print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); - putc ('\n', dump_file); - } + gswitch *s = gimple_build_switch (index_expr, + unshare_expr (default_label_expr), labels); + gimple_stmt_iterator gsi = gsi_start_bb (m_case_bb); + gsi_insert_after (&gsi, s, GSI_NEW_STMT); +} - switch_conversion sconv; - sconv.expand (as_a <gswitch *> (stmt)); - cfg_altered |= sconv.m_cfg_altered; - if (!sconv.m_reason) - { - if (dump_file) - { - fputs ("Switch converted\n", dump_file); - fputs ("--------------------------------\n", dump_file); - } +/* Return true when cluster starting at START and ending at END (inclusive) + can build a jump-table. */ - /* Make no effort to update the post-dominator tree. - It is actually not that hard for the transformations - we have performed, but it is not supported - by iterate_fix_dominators. */ - free_dominance_info (CDI_POST_DOMINATORS); - } - else - { - if (dump_file) - { - fputs ("Bailing out - ", dump_file); - fputs (sconv.m_reason, dump_file); - fputs ("\n--------------------------------\n", dump_file); - } - } - } - } +bool +jump_table_cluster::can_be_handled (const vec<cluster *> &clusters, + unsigned start, unsigned end) +{ + /* If the switch is relatively small such that the cost of one + indirect jump on the target are higher than the cost of a + decision tree, go with the decision tree. - return cfg_altered ? TODO_cleanup_cfg : 0;; + If range of values is much bigger than number of values, + or if it is too large to represent in a HOST_WIDE_INT, + make a sequence of conditional branches instead of a dispatch. + + The definition of "much bigger" depends on whether we are + optimizing for size or for speed. If the former, the maximum + ratio range/count = 3, because this was found to be the optimal + ratio for size on i686-pc-linux-gnu, see PR11823. The ratio + 10 is much older, and was probably selected after an extensive + benchmarking investigation on numerous platforms. Or maybe it + just made sense to someone at some point in the history of GCC, + who knows... */ + if (!flag_jump_tables) + return false; + + unsigned HOST_WIDE_INT max_ratio = optimize_insn_for_size_p () ? 3 : 10; + + unsigned HOST_WIDE_INT range = get_range (clusters[start]->get_low (), + clusters[end]->get_high ()); + /* Check overflow. */ + if (range == 0) + return false; + + unsigned HOST_WIDE_INT comparison_count = 0; + for (unsigned i = start; i <= end; i++) + { + simple_cluster *sc = static_cast<simple_cluster *> (clusters[i]); + comparison_count += sc->m_range_p ? 2 : 1; + } + + return range <= max_ratio * comparison_count; } -} // anon namespace +/* Return true if cluster starting at START and ending at END (inclusive) + is profitable transformation. */ -gimple_opt_pass * -make_pass_convert_switch (gcc::context *ctxt) +bool +jump_table_cluster::is_beneficial (const vec<cluster *> &, + unsigned start, unsigned end) { - return new pass_convert_switch (ctxt); + return end - start + 1 >= case_values_threshold (); } -struct case_node +/* Return true when RANGE of case values with UNIQ labels + can build a bit test. */ + +bool +bit_test_cluster::can_be_handled (unsigned HOST_WIDE_INT range, + unsigned int uniq) { - case_node *left; /* Left son in binary tree. */ - case_node *right; /* Right son in binary tree; - also node chain. */ - case_node *parent; /* Parent of node in binary tree. */ - tree low; /* Lowest index value for this label. */ - tree high; /* Highest index value for this label. */ - basic_block case_bb; /* Label to jump to when node matches. */ - tree case_label; /* Label to jump to when node matches. */ - profile_probability prob; /* Probability of taking this case. */ - profile_probability subtree_prob; /* Probability of reaching subtree - rooted at this node. */ -}; + /* Check overflow. */ + if (range == 0) + return 0; -typedef case_node *case_node_ptr; + if (range >= GET_MODE_BITSIZE (word_mode)) + return false; -static basic_block emit_case_nodes (basic_block, tree, case_node_ptr, - basic_block, tree, profile_probability, - tree, hash_map<tree, tree> *); + return uniq <= 3; +} -/* Return the smallest number of different values for which it is best to use a - jump-table instead of a tree of conditional branches. */ +/* Return true when cluster starting at START and ending at END (inclusive) + can build a bit test. */ -static unsigned int -case_values_threshold (void) +bool +bit_test_cluster::can_be_handled (const vec<cluster *> &clusters, + unsigned start, unsigned end) { - unsigned int threshold = PARAM_VALUE (PARAM_CASE_VALUES_THRESHOLD); + unsigned HOST_WIDE_INT range = get_range (clusters[start]->get_low (), + clusters[end]->get_high ()); + auto_bitmap dest_bbs; - if (threshold == 0) - threshold = targetm.case_values_threshold (); + for (unsigned i = start; i <= end; i++) + { + simple_cluster *sc = static_cast<simple_cluster *> (clusters[i]); + bitmap_set_bit (dest_bbs, sc->m_case_bb->index); + } - return threshold; + return can_be_handled (range, bitmap_count_bits (dest_bbs)); } -/* Reset the aux field of all outgoing edges of basic block BB. */ +/* Return true when COUNT of cases of UNIQ labels is beneficial for bit test + transformation. */ -static inline void -reset_out_edges_aux (basic_block bb) +bool +bit_test_cluster::is_beneficial (unsigned count, unsigned uniq) { - edge e; - edge_iterator ei; - FOR_EACH_EDGE (e, ei, bb->succs) - e->aux = (void *) 0; + return (((uniq == 1 && count >= 3) + || (uniq == 2 && count >= 5) + || (uniq == 3 && count >= 6))); +} + +/* Return true if cluster starting at START and ending at END (inclusive) + is profitable transformation. */ + +bool +bit_test_cluster::is_beneficial (const vec<cluster *> &clusters, + unsigned start, unsigned end) +{ + auto_bitmap dest_bbs; + + for (unsigned i = start; i <= end; i++) + { + simple_cluster *sc = static_cast<simple_cluster *> (clusters[i]); + bitmap_set_bit (dest_bbs, sc->m_case_bb->index); + } + + unsigned uniq = bitmap_count_bits (dest_bbs); + unsigned count = end - start + 1; + return is_beneficial (count, uniq); +} + +/* Comparison function for qsort to order bit tests by decreasing + probability of execution. */ + +int +case_bit_test::cmp (const void *p1, const void *p2) +{ + const struct case_bit_test *const d1 = (const struct case_bit_test *) p1; + const struct case_bit_test *const d2 = (const struct case_bit_test *) p2; + + if (d2->bits != d1->bits) + return d2->bits - d1->bits; + + /* Stabilize the sort. */ + return (LABEL_DECL_UID (CASE_LABEL (d2->label)) + - LABEL_DECL_UID (CASE_LABEL (d1->label))); +} + +/* Expand a switch statement by a short sequence of bit-wise + comparisons. "switch(x)" is effectively converted into + "if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are + integer constants. + + INDEX_EXPR is the value being switched on. + + MINVAL is the lowest case value of in the case nodes, + and RANGE is highest value minus MINVAL. MINVAL and RANGE + are not guaranteed to be of the same type as INDEX_EXPR + (the gimplifier doesn't change the type of case label values, + and MINVAL and RANGE are derived from those values). + MAXVAL is MINVAL + RANGE. + + There *MUST* be max_case_bit_tests or less unique case + node targets. */ + +void +bit_test_cluster::emit (tree index_expr, tree index_type, + tree, basic_block default_bb) +{ + struct case_bit_test test[m_max_case_bit_tests] = { {} }; + unsigned int i, j, k; + unsigned int count; + + tree unsigned_index_type = unsigned_type_for (index_type); + + gimple_stmt_iterator gsi; + gassign *shift_stmt; + + tree idx, tmp, csui; + tree word_type_node = lang_hooks.types.type_for_mode (word_mode, 1); + tree word_mode_zero = fold_convert (word_type_node, integer_zero_node); + tree word_mode_one = fold_convert (word_type_node, integer_one_node); + int prec = TYPE_PRECISION (word_type_node); + wide_int wone = wi::one (prec); + + tree minval = get_low (); + tree maxval = get_high (); + tree range = int_const_binop (MINUS_EXPR, maxval, minval); + + /* Go through all case labels, and collect the case labels, profile + counts, and other information we need to build the branch tests. */ + count = 0; + for (i = 0; i < m_cases.length (); i++) + { + unsigned int lo, hi; + simple_cluster *n = static_cast<simple_cluster *> (m_cases[i]); + for (k = 0; k < count; k++) + if (n->m_case_bb == test[k].target_bb) + break; + + if (k == count) + { + gcc_checking_assert (count < m_max_case_bit_tests); + test[k].mask = wi::zero (prec); + test[k].target_bb = n->m_case_bb; + test[k].label = n->m_case_label_expr; + test[k].bits = 1; + count++; + } + else + test[k].bits++; + + lo = tree_to_uhwi (int_const_binop (MINUS_EXPR, n->get_low (), minval)); + if (n->get_high () == NULL_TREE) + hi = lo; + else + hi = tree_to_uhwi (int_const_binop (MINUS_EXPR, n->get_high (), + minval)); + + for (j = lo; j <= hi; j++) + test[k].mask |= wi::lshift (wone, j); + } + + qsort (test, count, sizeof (*test), case_bit_test::cmp); + + /* If all values are in the 0 .. BITS_PER_WORD-1 range, we can get rid of + the minval subtractions, but it might make the mask constants more + expensive. So, compare the costs. */ + if (compare_tree_int (minval, 0) > 0 + && compare_tree_int (maxval, GET_MODE_BITSIZE (word_mode)) < 0) + { + int cost_diff; + HOST_WIDE_INT m = tree_to_uhwi (minval); + rtx reg = gen_raw_REG (word_mode, 10000); + bool speed_p = optimize_insn_for_speed_p (); + cost_diff = set_rtx_cost (gen_rtx_PLUS (word_mode, reg, + GEN_INT (-m)), speed_p); + for (i = 0; i < count; i++) + { + rtx r = immed_wide_int_const (test[i].mask, word_mode); + cost_diff += set_src_cost (gen_rtx_AND (word_mode, reg, r), + word_mode, speed_p); + r = immed_wide_int_const (wi::lshift (test[i].mask, m), word_mode); + cost_diff -= set_src_cost (gen_rtx_AND (word_mode, reg, r), + word_mode, speed_p); + } + if (cost_diff > 0) + { + for (i = 0; i < count; i++) + test[i].mask = wi::lshift (test[i].mask, m); + minval = build_zero_cst (TREE_TYPE (minval)); + range = maxval; + } + } + + /* Now build the test-and-branch code. */ + + gsi = gsi_last_bb (m_case_bb); + + /* idx = (unsigned)x - minval. */ + idx = fold_convert (unsigned_index_type, index_expr); + idx = fold_build2 (MINUS_EXPR, unsigned_index_type, idx, + fold_convert (unsigned_index_type, minval)); + idx = force_gimple_operand_gsi (&gsi, idx, + /*simple=*/true, NULL_TREE, + /*before=*/true, GSI_SAME_STMT); + + /* if (idx > range) goto default */ + range = force_gimple_operand_gsi (&gsi, + fold_convert (unsigned_index_type, range), + /*simple=*/true, NULL_TREE, + /*before=*/true, GSI_SAME_STMT); + tmp = fold_build2 (GT_EXPR, boolean_type_node, idx, range); + basic_block new_bb = hoist_edge_and_branch_if_true (&gsi, tmp, default_bb); + gsi = gsi_last_bb (new_bb); + + /* csui = (1 << (word_mode) idx) */ + csui = make_ssa_name (word_type_node); + tmp = fold_build2 (LSHIFT_EXPR, word_type_node, word_mode_one, + fold_convert (word_type_node, idx)); + tmp = force_gimple_operand_gsi (&gsi, tmp, + /*simple=*/false, NULL_TREE, + /*before=*/true, GSI_SAME_STMT); + shift_stmt = gimple_build_assign (csui, tmp); + gsi_insert_before (&gsi, shift_stmt, GSI_SAME_STMT); + update_stmt (shift_stmt); + + /* for each unique set of cases: + if (const & csui) goto target */ + for (k = 0; k < count; k++) + { + tmp = wide_int_to_tree (word_type_node, test[k].mask); + tmp = fold_build2 (BIT_AND_EXPR, word_type_node, csui, tmp); + tmp = force_gimple_operand_gsi (&gsi, tmp, + /*simple=*/true, NULL_TREE, + /*before=*/true, GSI_SAME_STMT); + tmp = fold_build2 (NE_EXPR, boolean_type_node, tmp, word_mode_zero); + new_bb = hoist_edge_and_branch_if_true (&gsi, tmp, test[k].target_bb); + gsi = gsi_last_bb (new_bb); + } + + /* We should have removed all edges now. */ + gcc_assert (EDGE_COUNT (gsi_bb (gsi)->succs) == 0); + + /* If nothing matched, go to the default label. */ + make_edge (gsi_bb (gsi), default_bb, EDGE_FALLTHRU); +} + +/* Split the basic block at the statement pointed to by GSIP, and insert + a branch to the target basic block of E_TRUE conditional on tree + expression COND. + + It is assumed that there is already an edge from the to-be-split + basic block to E_TRUE->dest block. This edge is removed, and the + profile information on the edge is re-used for the new conditional + jump. + + The CFG is updated. The dominator tree will not be valid after + this transformation, but the immediate dominators are updated if + UPDATE_DOMINATORS is true. + + Returns the newly created basic block. */ + +basic_block +bit_test_cluster::hoist_edge_and_branch_if_true (gimple_stmt_iterator *gsip, + tree cond, basic_block case_bb) +{ + tree tmp; + gcond *cond_stmt; + edge e_false; + basic_block new_bb, split_bb = gsi_bb (*gsip); + + edge e_true = make_edge (split_bb, case_bb, EDGE_TRUE_VALUE); + gcc_assert (e_true->src == split_bb); + + tmp = force_gimple_operand_gsi (gsip, cond, /*simple=*/true, NULL, + /*before=*/true, GSI_SAME_STMT); + cond_stmt = gimple_build_cond_from_tree (tmp, NULL_TREE, NULL_TREE); + gsi_insert_before (gsip, cond_stmt, GSI_SAME_STMT); + + e_false = split_block (split_bb, cond_stmt); + new_bb = e_false->dest; + redirect_edge_pred (e_true, split_bb); + + e_false->flags &= ~EDGE_FALLTHRU; + e_false->flags |= EDGE_FALSE_VALUE; + e_false->probability = e_true->probability.invert (); + new_bb->count = e_false->count (); + + return new_bb; } /* Compute the number of case labels that correspond to each outgoing edge of - STMT. Record this information in the aux field of the edge. */ + switch statement. Record this information in the aux field of the edge. */ -static inline void -compute_cases_per_edge (gswitch *stmt) +void +switch_decision_tree::compute_cases_per_edge () { - basic_block bb = gimple_bb (stmt); - reset_out_edges_aux (bb); - int ncases = gimple_switch_num_labels (stmt); + basic_block bb = gimple_bb (m_switch); + reset_out_edges_aux (); + int ncases = gimple_switch_num_labels (m_switch); for (int i = ncases - 1; i >= 1; --i) { - tree elt = gimple_switch_label (stmt, i); + tree elt = gimple_switch_label (m_switch, i); tree lab = CASE_LABEL (elt); basic_block case_bb = label_to_block_fn (cfun, lab); edge case_edge = find_edge (bb, case_bb); @@ -1143,61 +1450,242 @@ compute_cases_per_edge (gswitch *stmt) } } -/* Do the insertion of a case label into case_list. The labels are - fed to us in descending order from the sorted vector of case labels used - in the tree part of the middle end. So the list we construct is - sorted in ascending order. +/* Analyze switch statement and return true when the statement is expanded + as decision tree. */ + +bool +switch_decision_tree::analyze_switch_statement () +{ + unsigned l = gimple_switch_num_labels (m_switch); + basic_block bb = gimple_bb (m_switch); + auto_vec<cluster *> clusters; + clusters.create (l - 1); + + tree default_label = CASE_LABEL (gimple_switch_default_label (m_switch)); + basic_block default_bb = label_to_block_fn (cfun, default_label); + m_case_bbs.reserve (l); + m_case_bbs.quick_push (default_bb); + + compute_cases_per_edge (); + + for (unsigned i = 1; i < l; i++) + { + tree elt = gimple_switch_label (m_switch, i); + tree lab = CASE_LABEL (elt); + basic_block case_bb = label_to_block_fn (cfun, lab); + edge case_edge = find_edge (bb, case_bb); + tree low = CASE_LOW (elt); + tree high = CASE_HIGH (elt); + + profile_probability p + = case_edge->probability.apply_scale (1, (intptr_t) (case_edge->aux)); + clusters.quick_push (new simple_cluster (low, high, elt, case_bb, p)); + m_case_bbs.quick_push (case_bb); + } + + reset_out_edges_aux (); + + vec<cluster *> output; + output.create (1); + + /* Find whether the switch statement can be expanded with a method + different from decision tree. */ + unsigned end = clusters.length () - 1; + if (jump_table_cluster::can_be_handled (clusters, 0, end) + && jump_table_cluster::is_beneficial (clusters, 0, end)) + output.safe_push (new jump_table_cluster (clusters, 0, end)); + else if (bit_test_cluster::can_be_handled (clusters, 0, end) + && bit_test_cluster::is_beneficial (clusters, 0, end)) + output.safe_push (new bit_test_cluster (clusters, 0, end)); + else + output = clusters; + + if (dump_file) + { + fprintf (dump_file, ";; GIMPLE switch case clusters: "); + for (unsigned i = 0; i < output.length (); i++) + output[i]->dump (dump_file, dump_flags & TDF_DETAILS); + fprintf (dump_file, "\n"); + } - LABEL is the case label to be inserted. LOW and HIGH are the bounds - against which the index is compared to jump to LABEL and PROB is the - estimated probability LABEL is reached from the switch statement. */ + bool expanded = try_switch_expansion (output); -static case_node * -add_case_node (case_node *head, tree low, tree high, basic_block case_bb, - tree case_label, profile_probability prob, - object_allocator<case_node> &case_node_pool) + for (unsigned i = 0; i < output.length (); i++) + delete output[i]; + + return expanded; +} + +/* Attempt to expand CLUSTERS as a decision tree. Return true when + expanded. */ + +bool +switch_decision_tree::try_switch_expansion (vec<cluster *> &clusters) { - case_node *r; - - gcc_checking_assert (low); - gcc_checking_assert (high && (TREE_TYPE (low) == TREE_TYPE (high))); - - /* Add this label to the chain. */ - r = case_node_pool.allocate (); - r->low = low; - r->high = high; - r->case_bb = case_bb; - r->case_label = case_label; - r->parent = r->left = NULL; - r->prob = prob; - r->subtree_prob = prob; - r->right = head; - return r; + tree index_expr = gimple_switch_index (m_switch); + tree index_type = TREE_TYPE (index_expr); + basic_block bb = gimple_bb (m_switch); + + if (gimple_switch_num_labels (m_switch) == 1) + return false; + + /* Find the default case target label. */ + tree default_label_expr = CASE_LABEL (gimple_switch_default_label (m_switch)); + m_default_bb = label_to_block_fn (cfun, default_label_expr); + edge default_edge = find_edge (bb, m_default_bb); + + /* Do the insertion of a case label into m_case_list. The labels are + fed to us in descending order from the sorted vector of case labels used + in the tree part of the middle end. So the list we construct is + sorted in ascending order. */ + + for (int i = clusters.length () - 1; i >= 0; i--) + { + case_tree_node *r = m_case_list; + m_case_list = m_case_node_pool.allocate (); + m_case_list->m_right = r; + m_case_list->m_c = clusters[i]; + } + + record_phi_operand_mapping (); + + /* Split basic block that contains the gswitch statement. */ + gimple_stmt_iterator gsi = gsi_last_bb (bb); + edge e; + if (gsi_end_p (gsi)) + e = split_block_after_labels (bb); + else + { + gsi_prev (&gsi); + e = split_block (bb, gsi_stmt (gsi)); + } + bb = split_edge (e); + + /* Create new basic blocks for non-case clusters where specific expansion + needs to happen. */ + for (unsigned i = 0; i < clusters.length (); i++) + if (clusters[i]->get_type () != SIMPLE_CASE) + { + clusters[i]->m_case_bb = create_empty_bb (bb); + clusters[i]->m_case_bb->loop_father = bb->loop_father; + } + + /* Do not do an extra work for a single cluster. */ + if (clusters.length () == 1 + && clusters[0]->get_type () != SIMPLE_CASE) + clusters[0]->emit (index_expr, index_type, + gimple_switch_default_label (m_switch), m_default_bb); + else + { + emit (bb, index_expr, default_edge->probability, index_type); + + /* Emit cluster-specific switch handling. */ + for (unsigned i = 0; i < clusters.length (); i++) + if (clusters[i]->get_type () != SIMPLE_CASE) + clusters[i]->emit (index_expr, index_type, + gimple_switch_default_label (m_switch), + m_default_bb); + } + + fix_phi_operands_for_edges (); + + return true; } -/* Dump ROOT, a list or tree of case nodes, to file. */ +/* Before switch transformation, record all SSA_NAMEs defined in switch BB + and used in a label basic block. */ -static void -dump_case_nodes (FILE *f, case_node *root, int indent_step, int indent_level) +void +switch_decision_tree::record_phi_operand_mapping () { - if (root == 0) - return; - indent_level++; + basic_block switch_bb = gimple_bb (m_switch); + /* Record all PHI nodes that have to be fixed after conversion. */ + for (unsigned i = 0; i < m_case_bbs.length (); i++) + { + gphi_iterator gsi; + basic_block bb = m_case_bbs[i]; + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gphi *phi = gsi.phi (); - dump_case_nodes (f, root->left, indent_step, indent_level); + for (unsigned i = 0; i < gimple_phi_num_args (phi); i++) + { + basic_block phi_src_bb = gimple_phi_arg_edge (phi, i)->src; + if (phi_src_bb == switch_bb) + { + tree def = gimple_phi_arg_def (phi, i); + tree result = gimple_phi_result (phi); + m_phi_mapping.put (result, def); + break; + } + } + } + } +} - fputs (";; ", f); - fprintf (f, "%*s", indent_step * indent_level, ""); - print_dec (wi::to_wide (root->low), f, TYPE_SIGN (TREE_TYPE (root->low))); - if (!tree_int_cst_equal (root->low, root->high)) +/* Append new operands to PHI statements that were introduced due to + addition of new edges to case labels. */ + +void +switch_decision_tree::fix_phi_operands_for_edges () +{ + gphi_iterator gsi; + + for (unsigned i = 0; i < m_case_bbs.length (); i++) { - fprintf (f, " ... "); - print_dec (wi::to_wide (root->high), f, - TYPE_SIGN (TREE_TYPE (root->high))); + basic_block bb = m_case_bbs[i]; + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gphi *phi = gsi.phi (); + for (unsigned j = 0; j < gimple_phi_num_args (phi); j++) + { + tree def = gimple_phi_arg_def (phi, j); + if (def == NULL_TREE) + { + edge e = gimple_phi_arg_edge (phi, j); + tree *definition + = m_phi_mapping.get (gimple_phi_result (phi)); + gcc_assert (definition); + add_phi_arg (phi, *definition, e, UNKNOWN_LOCATION); + } + } + } + } +} + +/* Generate a decision tree, switching on INDEX_EXPR and jumping to + one of the labels in CASE_LIST or to the DEFAULT_LABEL. + + We generate a binary decision tree to select the appropriate target + code. */ + +void +switch_decision_tree::emit (basic_block bb, tree index_expr, + profile_probability default_prob, tree index_type) +{ + balance_case_nodes (&m_case_list, NULL); + + if (dump_file) + dump_function_to_file (current_function_decl, dump_file, dump_flags); + if (dump_file && (dump_flags & TDF_DETAILS)) + { + int indent_step = ceil_log2 (TYPE_PRECISION (index_type)) + 2; + fprintf (dump_file, ";; Expanding GIMPLE switch as decision tree:\n"); + gcc_assert (m_case_list != NULL); + dump_case_nodes (dump_file, m_case_list, indent_step, 0); } - fputs ("\n", f); - dump_case_nodes (f, root->right, indent_step, indent_level); + bb = emit_case_nodes (bb, index_expr, m_case_list, default_prob, index_type); + + if (bb) + emit_jump (bb, m_default_bb); + + /* Remove all edges and do just an edge that will reach default_bb. */ + bb = gimple_bb (m_switch); + gimple_stmt_iterator gsi = gsi_last_bb (bb); + gsi_remove (&gsi, true); + + delete_basic_block (bb); } /* Take an ordered list of case nodes @@ -1210,28 +1698,29 @@ dump_case_nodes (FILE *f, case_node *root, int indent_step, int indent_level) then attached to the pivot as left and right branches. Each branch is then transformed recursively. */ -static void -balance_case_nodes (case_node_ptr *head, case_node_ptr parent) +void +switch_decision_tree::balance_case_nodes (case_tree_node **head, + case_tree_node *parent) { - case_node_ptr np; + case_tree_node *np; np = *head; if (np) { int i = 0; int ranges = 0; - case_node_ptr *npp; - case_node_ptr left; + case_tree_node **npp; + case_tree_node *left; /* Count the number of entries on branch. Also count the ranges. */ while (np) { - if (!tree_int_cst_equal (np->low, np->high)) + if (!tree_int_cst_equal (np->m_c->get_low (), np->m_c->get_high ())) ranges++; i++; - np = np->right; + np = np->m_right; } if (i > 2) @@ -1242,7 +1731,7 @@ balance_case_nodes (case_node_ptr *head, case_node_ptr parent) /* If there are just three nodes, split at the middle one. */ if (i == 3) - npp = &(*npp)->right; + npp = &(*npp)->m_right; else { /* Find the place in the list that bisects the list's total cost, @@ -1252,320 +1741,247 @@ balance_case_nodes (case_node_ptr *head, case_node_ptr parent) while (1) { /* Skip nodes while their cost does not reach that amount. */ - if (!tree_int_cst_equal ((*npp)->low, (*npp)->high)) + if (!tree_int_cst_equal ((*npp)->m_c->get_low (), + (*npp)->m_c->get_high ())) i--; i--; if (i <= 0) break; - npp = &(*npp)->right; + npp = &(*npp)->m_right; } } *head = np = *npp; *npp = 0; - np->parent = parent; - np->left = left; + np->m_parent = parent; + np->m_left = left; /* Optimize each of the two split parts. */ - balance_case_nodes (&np->left, np); - balance_case_nodes (&np->right, np); - np->subtree_prob = np->prob; - np->subtree_prob += np->left->subtree_prob; - np->subtree_prob += np->right->subtree_prob; + balance_case_nodes (&np->m_left, np); + balance_case_nodes (&np->m_right, np); + np->m_c->m_subtree_prob = np->m_c->m_prob; + np->m_c->m_subtree_prob += np->m_left->m_c->m_subtree_prob; + np->m_c->m_subtree_prob += np->m_right->m_c->m_subtree_prob; } else { /* Else leave this branch as one level, but fill in `parent' fields. */ np = *head; - np->parent = parent; - np->subtree_prob = np->prob; - for (; np->right; np = np->right) + np->m_parent = parent; + np->m_c->m_subtree_prob = np->m_c->m_prob; + for (; np->m_right; np = np->m_right) { - np->right->parent = np; - (*head)->subtree_prob += np->right->subtree_prob; + np->m_right->m_parent = np; + (*head)->m_c->m_subtree_prob += np->m_right->m_c->m_subtree_prob; } } } } -/* Return true if a switch should be expanded as a decision tree. - RANGE is the difference between highest and lowest case. - UNIQ is number of unique case node targets, not counting the default case. - COUNT is the number of comparisons needed, not counting the default case. */ +/* Dump ROOT, a list or tree of case nodes, to file. */ -static bool -expand_switch_as_decision_tree_p (tree range, - unsigned int uniq ATTRIBUTE_UNUSED, - unsigned int count) +void +switch_decision_tree::dump_case_nodes (FILE *f, case_tree_node *root, + int indent_step, int indent_level) { - int max_ratio; - - /* If neither casesi or tablejump is available, or flag_jump_tables - over-ruled us, we really have no choice. */ - if (!targetm.have_casesi () && !targetm.have_tablejump ()) - return true; - if (!flag_jump_tables) - return true; -#ifndef ASM_OUTPUT_ADDR_DIFF_ELT - if (flag_pic) - return true; -#endif - - /* If the switch is relatively small such that the cost of one - indirect jump on the target are higher than the cost of a - decision tree, go with the decision tree. - - If range of values is much bigger than number of values, - or if it is too large to represent in a HOST_WIDE_INT, - make a sequence of conditional branches instead of a dispatch. - - The definition of "much bigger" depends on whether we are - optimizing for size or for speed. If the former, the maximum - ratio range/count = 3, because this was found to be the optimal - ratio for size on i686-pc-linux-gnu, see PR11823. The ratio - 10 is much older, and was probably selected after an extensive - benchmarking investigation on numerous platforms. Or maybe it - just made sense to someone at some point in the history of GCC, - who knows... */ - max_ratio = optimize_insn_for_size_p () ? 3 : 10; - if (count < case_values_threshold () || !tree_fits_uhwi_p (range) - || compare_tree_int (range, max_ratio * count) > 0) - return true; + if (root == 0) + return; + indent_level++; - return false; -} + dump_case_nodes (f, root->m_left, indent_step, indent_level); -static void -fix_phi_operands_for_edge (edge e, hash_map<tree, tree> *phi_mapping) -{ - basic_block bb = e->dest; - gphi_iterator gsi; - for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) - { - gphi *phi = gsi.phi (); + fputs (";; ", f); + fprintf (f, "%*s", indent_step * indent_level, ""); + root->m_c->dump (f); + root->m_c->m_prob.dump (f); + fputs ("\n", f); - tree *definition = phi_mapping->get (gimple_phi_result (phi)); - if (definition) - add_phi_arg (phi, *definition, e, UNKNOWN_LOCATION); - } + dump_case_nodes (f, root->m_right, indent_step, indent_level); } /* Add an unconditional jump to CASE_BB that happens in basic block BB. */ -static void -emit_jump (basic_block bb, basic_block case_bb, - hash_map<tree, tree> *phi_mapping) +void +switch_decision_tree::emit_jump (basic_block bb, basic_block case_bb) { edge e = single_succ_edge (bb); redirect_edge_succ (e, case_bb); - fix_phi_operands_for_edge (e, phi_mapping); } -/* Generate a decision tree, switching on INDEX_EXPR and jumping to - one of the labels in CASE_LIST or to the DEFAULT_LABEL. - DEFAULT_PROB is the estimated probability that it jumps to - DEFAULT_LABEL. - - We generate a binary decision tree to select the appropriate target - code. */ +/* Generate code to compare OP0 with OP1 so that the condition codes are + set and to jump to LABEL_BB if the condition is true. + COMPARISON is the GIMPLE comparison (EQ, NE, GT, etc.). + PROB is the probability of jumping to LABEL_BB. */ -static void -emit_case_decision_tree (gswitch *s, tree index_expr, tree index_type, - case_node_ptr case_list, basic_block default_bb, - tree default_label, profile_probability default_prob, - hash_map<tree, tree> *phi_mapping) +basic_block +switch_decision_tree::emit_cmp_and_jump_insns (basic_block bb, tree op0, + tree op1, tree_code comparison, + basic_block label_bb, + profile_probability prob) { - balance_case_nodes (&case_list, NULL); - - if (dump_file) - dump_function_to_file (current_function_decl, dump_file, dump_flags); - if (dump_file && (dump_flags & TDF_DETAILS)) - { - int indent_step = ceil_log2 (TYPE_PRECISION (index_type)) + 2; - fprintf (dump_file, ";; Expanding GIMPLE switch as decision tree:\n"); - dump_case_nodes (dump_file, case_list, indent_step, 0); - } + // TODO: it's once called with lhs != index. + op1 = fold_convert (TREE_TYPE (op0), op1); - basic_block bb = gimple_bb (s); + gcond *cond = gimple_build_cond (comparison, op0, op1, NULL_TREE, NULL_TREE); gimple_stmt_iterator gsi = gsi_last_bb (bb); - edge e; - if (gsi_end_p (gsi)) - e = split_block_after_labels (bb); - else - { - gsi_prev (&gsi); - e = split_block (bb, gsi_stmt (gsi)); - } - bb = split_edge (e); + gsi_insert_after (&gsi, cond, GSI_NEW_STMT); - bb = emit_case_nodes (bb, index_expr, case_list, default_bb, default_label, - default_prob, index_type, phi_mapping); + gcc_assert (single_succ_p (bb)); - if (bb) - emit_jump (bb, default_bb, phi_mapping); + /* Make a new basic block where false branch will take place. */ + edge false_edge = split_block (bb, cond); + false_edge->flags = EDGE_FALSE_VALUE; + false_edge->probability = prob.invert (); - /* Remove all edges and do just an edge that will reach default_bb. */ - gsi = gsi_last_bb (gimple_bb (s)); - gsi_remove (&gsi, true); + edge true_edge = make_edge (bb, label_bb, EDGE_TRUE_VALUE); + true_edge->probability = prob; + + return false_edge->dest; } -static void -record_phi_operand_mapping (const vec<basic_block> bbs, basic_block switch_bb, - hash_map <tree, tree> *map) +/* Emit step-by-step code to select a case for the value of INDEX. + The thus generated decision tree follows the form of the + case-node binary tree NODE, whose nodes represent test conditions. + DEFAULT_PROB is probability of cases leading to default BB. + INDEX_TYPE is the type of the index of the switch. */ + +basic_block +switch_decision_tree::emit_case_nodes (basic_block bb, tree index, + case_tree_node *node, + profile_probability default_prob, + tree index_type) { - /* Record all PHI nodes that have to be fixed after conversion. */ - for (unsigned i = 0; i < bbs.length (); i++) - { - basic_block bb = bbs[i]; + /* If node is null, we are done. */ + if (node == NULL) + return bb; - gphi_iterator gsi; - for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) - { - gphi *phi = gsi.phi (); + /* Branch to a label where we will handle it later. */ + basic_block test_bb = split_edge (single_succ_edge (bb)); + redirect_edge_succ (single_pred_edge (test_bb), + single_succ_edge (bb)->dest); - for (unsigned i = 0; i < gimple_phi_num_args (phi); i++) - { - basic_block phi_src_bb = gimple_phi_arg_edge (phi, i)->src; - if (phi_src_bb == switch_bb) - { - tree def = gimple_phi_arg_def (phi, i); - tree result = gimple_phi_result (phi); - map->put (result, def); - break; - } - } - } - } -} + profile_probability probability + = (node->m_right + ? node->m_right->m_c->m_subtree_prob : profile_probability::never ()); + probability = ((probability + default_prob.apply_scale (1, 2)) + / (node->m_c->m_subtree_prob + default_prob)); + bb = emit_cmp_and_jump_insns (bb, index, node->m_c->get_high (), GT_EXPR, + test_bb, probability); + default_prob = default_prob.apply_scale (1, 2); -/* Attempt to expand gimple switch STMT to a decision tree. */ + /* Value belongs to this node or to the left-hand subtree. */ + probability = node->m_c->m_prob / + (node->m_c->m_subtree_prob + default_prob); + bb = emit_cmp_and_jump_insns (bb, index, node->m_c->get_low (), GE_EXPR, + node->m_c->m_case_bb, probability); -static bool -try_switch_expansion (gswitch *stmt) -{ - tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE; - basic_block default_bb; - unsigned int count, uniq; - int i; - int ncases = gimple_switch_num_labels (stmt); - tree index_expr = gimple_switch_index (stmt); - tree index_type = TREE_TYPE (index_expr); - tree elt; - basic_block bb = gimple_bb (stmt); + /* Handle the left-hand subtree. */ + bb = emit_case_nodes (bb, index, node->m_left, + default_prob, index_type); - hash_map<tree, tree> phi_mapping; - auto_vec<basic_block> case_bbs; + /* If the left-hand subtree fell through, + don't let it fall into the right-hand subtree. */ + if (m_default_bb) + emit_jump (bb, m_default_bb); - /* A list of case labels; it is first built as a list and it may then - be rearranged into a nearly balanced binary tree. */ - case_node *case_list = 0; + bb = emit_case_nodes (test_bb, index, node->m_right, + default_prob, index_type); - /* A pool for case nodes. */ - object_allocator<case_node> case_node_pool ("struct case_node pool"); + return bb; +} - /* cleanup_tree_cfg removes all SWITCH_EXPR with their index - expressions being INTEGER_CST. */ - gcc_assert (TREE_CODE (index_expr) != INTEGER_CST); +/* The main function of the pass scans statements for switches and invokes + process_switch on them. */ - if (ncases == 1) - return false; +namespace { - /* Find the default case target label. */ - tree default_label = CASE_LABEL (gimple_switch_default_label (stmt)); - default_bb = label_to_block_fn (cfun, default_label); - edge default_edge = find_edge (bb, default_bb); - profile_probability default_prob = default_edge->probability; - case_bbs.safe_push (default_bb); - - /* Get upper and lower bounds of case values. */ - elt = gimple_switch_label (stmt, 1); - minval = fold_convert (index_type, CASE_LOW (elt)); - elt = gimple_switch_label (stmt, ncases - 1); - if (CASE_HIGH (elt)) - maxval = fold_convert (index_type, CASE_HIGH (elt)); - else - maxval = fold_convert (index_type, CASE_LOW (elt)); +const pass_data pass_data_convert_switch = +{ + GIMPLE_PASS, /* type */ + "switchconv", /* name */ + OPTGROUP_NONE, /* optinfo_flags */ + TV_TREE_SWITCH_CONVERSION, /* tv_id */ + ( PROP_cfg | PROP_ssa ), /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_update_ssa, /* todo_flags_finish */ +}; - /* Compute span of values. */ - range = fold_build2 (MINUS_EXPR, index_type, maxval, minval); +class pass_convert_switch : public gimple_opt_pass +{ +public: + pass_convert_switch (gcc::context *ctxt) + : gimple_opt_pass (pass_data_convert_switch, ctxt) + {} - /* Listify the labels queue and gather some numbers to decide - how to expand this switch. */ - uniq = 0; - count = 0; - hash_set<tree> seen_labels; - compute_cases_per_edge (stmt); + /* opt_pass methods: */ + virtual bool gate (function *) { return flag_tree_switch_conversion != 0; } + virtual unsigned int execute (function *); - for (i = ncases - 1; i >= 1; --i) - { - elt = gimple_switch_label (stmt, i); - tree low = CASE_LOW (elt); - gcc_assert (low); - tree high = CASE_HIGH (elt); - gcc_assert (!high || tree_int_cst_lt (low, high)); - tree lab = CASE_LABEL (elt); +}; // class pass_convert_switch - /* Count the elements. - A range counts double, since it requires two compares. */ - count++; - if (high) - count++; - - /* If we have not seen this label yet, then increase the - number of unique case node targets seen. */ - if (!seen_labels.add (lab)) - uniq++; - - /* The bounds on the case range, LOW and HIGH, have to be converted - to case's index type TYPE. Note that the original type of the - case index in the source code is usually "lost" during - gimplification due to type promotion, but the case labels retain the - original type. Make sure to drop overflow flags. */ - low = fold_convert (index_type, low); - if (TREE_OVERFLOW (low)) - low = wide_int_to_tree (index_type, wi::to_wide (low)); - - /* The canonical from of a case label in GIMPLE is that a simple case - has an empty CASE_HIGH. For the casesi and tablejump expanders, - the back ends want simple cases to have high == low. */ - if (!high) - high = low; - high = fold_convert (index_type, high); - if (TREE_OVERFLOW (high)) - high = wide_int_to_tree (index_type, wi::to_wide (high)); +unsigned int +pass_convert_switch::execute (function *fun) +{ + basic_block bb; + bool cfg_altered = false; - basic_block case_bb = label_to_block_fn (cfun, lab); - edge case_edge = find_edge (bb, case_bb); - case_list = add_case_node ( - case_list, low, high, case_bb, lab, - case_edge->probability.apply_scale (1, (intptr_t) (case_edge->aux)), - case_node_pool); + FOR_EACH_BB_FN (bb, fun) + { + gimple *stmt = last_stmt (bb); + if (stmt && gimple_code (stmt) == GIMPLE_SWITCH) + { + if (dump_file) + { + expanded_location loc = expand_location (gimple_location (stmt)); - case_bbs.safe_push (case_bb); - } - reset_out_edges_aux (bb); - record_phi_operand_mapping (case_bbs, bb, &phi_mapping); + fprintf (dump_file, "beginning to process the following " + "SWITCH statement (%s:%d) : ------- \n", + loc.file, loc.line); + print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); + putc ('\n', dump_file); + } - /* cleanup_tree_cfg removes all SWITCH_EXPR with a single - destination, such as one with a default case only. - It also removes cases that are out of range for the switch - type, so we should never get a zero here. */ - gcc_assert (count > 0); + switch_conversion sconv; + sconv.expand (as_a <gswitch *> (stmt)); + cfg_altered |= sconv.m_cfg_altered; + if (!sconv.m_reason) + { + if (dump_file) + { + fputs ("Switch converted\n", dump_file); + fputs ("--------------------------------\n", dump_file); + } - /* Decide how to expand this switch. - The two options at this point are a dispatch table (casesi or - tablejump) or a decision tree. */ + /* Make no effort to update the post-dominator tree. + It is actually not that hard for the transformations + we have performed, but it is not supported + by iterate_fix_dominators. */ + free_dominance_info (CDI_POST_DOMINATORS); + } + else + { + if (dump_file) + { + fputs ("Bailing out - ", dump_file); + fputs (sconv.m_reason, dump_file); + fputs ("\n--------------------------------\n", dump_file); + } + } + } + } - if (expand_switch_as_decision_tree_p (range, uniq, count)) - { - emit_case_decision_tree (stmt, index_expr, index_type, case_list, - default_bb, default_label, default_prob, - &phi_mapping); - return true; - } + return cfg_altered ? TODO_cleanup_cfg : 0;; +} - return false; +} // anon namespace + +gimple_opt_pass * +make_pass_convert_switch (gcc::context *ctxt) +{ + return new pass_convert_switch (ctxt); } /* The main function of the pass scans statements for switches and invokes @@ -1614,23 +2030,35 @@ pass_lower_switch<O0>::execute (function *fun) basic_block bb; bool expanded = false; + auto_vec<gimple *> switch_statements; + switch_statements.create (1); + FOR_EACH_BB_FN (bb, fun) { gimple *stmt = last_stmt (bb); if (stmt && gimple_code (stmt) == GIMPLE_SWITCH) + switch_statements.safe_push (stmt); + } + + for (unsigned i = 0; i < switch_statements.length (); i++) + { + gimple *stmt = switch_statements[i]; + if (dump_file) { - if (dump_file) - { - expanded_location loc = expand_location (gimple_location (stmt)); + expanded_location loc = expand_location (gimple_location (stmt)); - fprintf (dump_file, "beginning to process the following " - "SWITCH statement (%s:%d) : ------- \n", - loc.file, loc.line); - print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); - putc ('\n', dump_file); - } + fprintf (dump_file, "beginning to process the following " + "SWITCH statement (%s:%d) : ------- \n", + loc.file, loc.line); + print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); + putc ('\n', dump_file); + } - expanded |= try_switch_expansion (as_a<gswitch *> (stmt)); + gswitch *swtch = dyn_cast<gswitch *> (stmt); + if (swtch) + { + switch_decision_tree dt (swtch); + expanded |= dt.analyze_switch_statement (); } } @@ -1657,112 +2085,4 @@ make_pass_lower_switch (gcc::context *ctxt) return new pass_lower_switch<false> (ctxt); } -/* Generate code to compare X with Y so that the condition codes are - set and to jump to LABEL if the condition is true. If X is a - constant and Y is not a constant, then the comparison is swapped to - ensure that the comparison RTL has the canonical form. - - UNSIGNEDP nonzero says that X and Y are unsigned; this matters if they - need to be widened. UNSIGNEDP is also used to select the proper - branch condition code. - - If X and Y have mode BLKmode, then SIZE specifies the size of both X and Y. - - MODE is the mode of the inputs (in case they are const_int). - - COMPARISON is the rtl operator to compare with (EQ, NE, GT, etc.). - It will be potentially converted into an unsigned variant based on - UNSIGNEDP to select a proper jump instruction. - - PROB is the probability of jumping to LABEL. */ - -static basic_block -emit_cmp_and_jump_insns (basic_block bb, tree op0, tree op1, - tree_code comparison, basic_block label_bb, - profile_probability prob, - hash_map<tree, tree> *phi_mapping) -{ - gcond *cond = gimple_build_cond (comparison, op0, op1, NULL_TREE, NULL_TREE); - gimple_stmt_iterator gsi = gsi_last_bb (bb); - gsi_insert_after (&gsi, cond, GSI_NEW_STMT); - - gcc_assert (single_succ_p (bb)); - - /* Make a new basic block where false branch will take place. */ - edge false_edge = split_block (bb, cond); - false_edge->flags = EDGE_FALSE_VALUE; - false_edge->probability = prob.invert (); - - edge true_edge = make_edge (bb, label_bb, EDGE_TRUE_VALUE); - fix_phi_operands_for_edge (true_edge, phi_mapping); - true_edge->probability = prob; - - return false_edge->dest; -} - -/* Computes the conditional probability of jumping to a target if the branch - instruction is executed. - TARGET_PROB is the estimated probability of jumping to a target relative - to some basic block BB. - BASE_PROB is the probability of reaching the branch instruction relative - to the same basic block BB. */ - -static inline profile_probability -conditional_probability (profile_probability target_prob, - profile_probability base_prob) -{ - return target_prob / base_prob; -} - -/* Emit step-by-step code to select a case for the value of INDEX. - The thus generated decision tree follows the form of the - case-node binary tree NODE, whose nodes represent test conditions. - INDEX_TYPE is the type of the index of the switch. */ - -static basic_block -emit_case_nodes (basic_block bb, tree index, case_node_ptr node, - basic_block default_bb, tree default_label, - profile_probability default_prob, tree index_type, - hash_map<tree, tree> *phi_mapping) -{ - /* If node is null, we are done. */ - if (node == NULL) - return bb; - /* Branch to a label where we will handle it later. */ - basic_block test_bb = split_edge (single_succ_edge (bb)); - redirect_edge_succ (single_pred_edge (test_bb), - single_succ_edge (bb)->dest); - - profile_probability probability - = node->right ? node->right->subtree_prob : profile_probability::never (); - probability - = conditional_probability (probability + default_prob.apply_scale (1, 2), - node->subtree_prob + default_prob); - bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR, - test_bb, probability, phi_mapping); - default_prob = default_prob.apply_scale (1, 2); - - /* Value belongs to this node or to the left-hand subtree. */ - probability - = conditional_probability (node->prob, node->subtree_prob + default_prob); - bb = emit_cmp_and_jump_insns (bb, index, node->low, GE_EXPR, - node->case_bb, probability, - phi_mapping); - - /* Handle the left-hand subtree. */ - bb = emit_case_nodes (bb, index, node->left, default_bb, - default_label, default_prob, index_type, - phi_mapping); - - /* If the left-hand subtree fell through, - don't let it fall into the right-hand subtree. */ - if (default_bb) - emit_jump (bb, default_bb, phi_mapping); - - bb = emit_case_nodes (test_bb, index, node->right, default_bb, - default_label, default_prob, index_type, - phi_mapping); - - return bb; -} |