| /* Lower GIMPLE_SWITCH expressions to something more efficient than |
| a jump table. |
| Copyright (C) 2006-2017 Free Software Foundation, Inc. |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify it |
| under the terms of the GNU General Public License as published by the |
| Free Software Foundation; either version 3, or (at your option) any |
| later version. |
| |
| GCC is distributed in the hope that it will be useful, but WITHOUT |
| ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GCC; see the file COPYING3. If not, write to the Free |
| Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301, USA. */ |
| |
| /* This file handles the lowering of GIMPLE_SWITCH to an indexed |
| load, or a series of bit-test-and-branch expressions. */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "backend.h" |
| #include "insn-codes.h" |
| #include "rtl.h" |
| #include "tree.h" |
| #include "gimple.h" |
| #include "cfghooks.h" |
| #include "tree-pass.h" |
| #include "ssa.h" |
| #include "optabs-tree.h" |
| #include "cgraph.h" |
| #include "gimple-pretty-print.h" |
| #include "params.h" |
| #include "fold-const.h" |
| #include "varasm.h" |
| #include "stor-layout.h" |
| #include "cfganal.h" |
| #include "gimplify.h" |
| #include "gimple-iterator.h" |
| #include "gimplify-me.h" |
| #include "tree-cfg.h" |
| #include "cfgloop.h" |
| |
| /* ??? For lang_hooks.types.type_for_mode, but is there a word_mode |
| type in the GIMPLE type system that is language-independent? */ |
| #include "langhooks.h" |
| |
| |
| /* Maximum number of case bit tests. |
| FIXME: This should be derived from PARAM_CASE_VALUES_THRESHOLD and |
| targetm.case_values_threshold(), or be its own param. */ |
| #define MAX_CASE_BIT_TESTS 3 |
| |
| /* 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. */ |
| |
| static basic_block |
| hoist_edge_and_branch_if_true (gimple_stmt_iterator *gsip, |
| tree cond, edge e_true, |
| bool update_dominators) |
| { |
| tree tmp; |
| gcond *cond_stmt; |
| edge e_false; |
| basic_block new_bb, split_bb = gsi_bb (*gsip); |
| bool dominated_e_true = false; |
| |
| gcc_assert (e_true->src == split_bb); |
| |
| if (update_dominators |
| && get_immediate_dominator (CDI_DOMINATORS, e_true->dest) == split_bb) |
| dominated_e_true = true; |
| |
| 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_true->flags &= ~EDGE_FALLTHRU; |
| e_true->flags |= EDGE_TRUE_VALUE; |
| |
| e_false->flags &= ~EDGE_FALLTHRU; |
| e_false->flags |= EDGE_FALSE_VALUE; |
| e_false->probability = REG_BR_PROB_BASE - e_true->probability; |
| e_false->count = split_bb->count - e_true->count; |
| new_bb->count = e_false->count; |
| |
| if (update_dominators) |
| { |
| if (dominated_e_true) |
| set_immediate_dominator (CDI_DOMINATORS, e_true->dest, split_bb); |
| set_immediate_dominator (CDI_DOMINATORS, e_false->dest, split_bb); |
| } |
| |
| return new_bb; |
| } |
| |
| |
| /* Return true if a switch should be expanded as a bit test. |
| 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. */ |
| |
| static bool |
| expand_switch_using_bit_tests_p (tree range, |
| unsigned int uniq, |
| unsigned int count, bool speed_p) |
| { |
| return (((uniq == 1 && count >= 3) |
| || (uniq == 2 && count >= 5) |
| || (uniq == 3 && count >= 6)) |
| && lshift_cheap_p (speed_p) |
| && compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0 |
| && compare_tree_int (range, 0) > 0); |
| } |
| |
| /* Implement switch statements with bit tests |
| |
| A GIMPLE switch statement can be expanded to a short sequence of bit-wise |
| comparisons. "switch(x)" is converted into "if ((1 << (x-MINVAL)) & CST)" |
| where CST and MINVAL are integer constants. This is better than a series |
| of compare-and-banch insns in some cases, e.g. we can implement: |
| |
| if ((x==4) || (x==6) || (x==9) || (x==11)) |
| |
| as a single bit test: |
| |
| if ((1<<x) & ((1<<4)|(1<<6)|(1<<9)|(1<<11))) |
| |
| This transformation is only applied if the number of case targets is small, |
| if CST constains at least 3 bits, and "1 << x" is cheap. The bit tests are |
| performed in "word_mode". |
| |
| The following example shows the code the transformation generates: |
| |
| int bar(int x) |
| { |
| switch (x) |
| { |
| case '0': case '1': case '2': case '3': case '4': |
| case '5': case '6': case '7': case '8': case '9': |
| case 'A': case 'B': case 'C': case 'D': case 'E': |
| case 'F': |
| return 1; |
| } |
| return 0; |
| } |
| |
| ==> |
| |
| bar (int x) |
| { |
| tmp1 = x - 48; |
| if (tmp1 > (70 - 48)) goto L2; |
| tmp2 = 1 << tmp1; |
| tmp3 = 0b11111100000001111111111; |
| if ((tmp2 & tmp3) != 0) goto L1 ; else goto L2; |
| L1: |
| return 1; |
| L2: |
| return 0; |
| } |
| |
| TODO: There are still some improvements to this transformation that could |
| be implemented: |
| |
| * A narrower mode than word_mode could be used if that is cheaper, e.g. |
| for x86_64 where a narrower-mode shift may result in smaller code. |
| |
| * The compounded constant could be shifted rather than the one. The |
| test would be either on the sign bit or on the least significant bit, |
| depending on the direction of the shift. On some machines, the test |
| for the branch would be free if the bit to test is already set by the |
| shift operation. |
| |
| This transformation was contributed by Roger Sayle, see this e-mail: |
| http://gcc.gnu.org/ml/gcc-patches/2003-01/msg01950.html |
| */ |
| |
| /* A case_bit_test represents a set of case nodes that may be |
| selected from using a bit-wise comparison. HI and LO hold |
| the integer to be tested against, TARGET_EDGE contains the |
| edge to the basic block to jump to upon success and BITS |
| counts the number of case nodes handled by this test, |
| typically the number of bits set in HI:LO. The LABEL field |
| is used to quickly identify all cases in this set without |
| looking at label_to_block for every case label. */ |
| |
| struct case_bit_test |
| { |
| wide_int mask; |
| edge target_edge; |
| tree label; |
| int bits; |
| }; |
| |
| /* Comparison function for qsort to order bit tests by decreasing |
| probability of execution. Our best guess comes from a measured |
| profile. If the profile counts are equal, break even on the |
| number of case nodes, i.e. the node with the most cases gets |
| tested first. |
| |
| TODO: Actually this currently runs before a profile is available. |
| Therefore the case-as-bit-tests transformation should be done |
| later in the pass pipeline, or something along the lines of |
| "Efficient and effective branch reordering using profile data" |
| (Yang et. al., 2002) should be implemented (although, how good |
| is a paper is called "Efficient and effective ..." when the |
| latter is implied by the former, but oh well...). */ |
| |
| static 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->target_edge->count != d1->target_edge->count) |
| return d2->target_edge->count - d1->target_edge->count; |
| if (d2->bits != d1->bits) |
| return d2->bits - d1->bits; |
| |
| /* Stabilize the sort. */ |
| return LABEL_DECL_UID (d2->label) - LABEL_DECL_UID (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. */ |
| |
| static void |
| emit_case_bit_tests (gswitch *swtch, tree index_expr, |
| tree minval, tree range, tree maxval) |
| { |
| struct case_bit_test test[MAX_CASE_BIT_TESTS]; |
| unsigned int i, j, k; |
| unsigned int count; |
| |
| basic_block switch_bb = gimple_bb (swtch); |
| basic_block default_bb, new_default_bb, new_bb; |
| edge default_edge; |
| bool update_dom = dom_info_available_p (CDI_DOMINATORS); |
| |
| vec<basic_block> bbs_to_fix_dom = vNULL; |
| |
| tree index_type = TREE_TYPE (index_expr); |
| tree unsigned_index_type = unsigned_type_for (index_type); |
| unsigned int branch_num = gimple_switch_num_labels (swtch); |
| |
| 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); |
| |
| memset (&test, 0, sizeof (test)); |
| |
| /* Get the edge for the default case. */ |
| tmp = gimple_switch_default_label (swtch); |
| default_bb = label_to_block (CASE_LABEL (tmp)); |
| default_edge = find_edge (switch_bb, default_bb); |
| |
| /* 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 = 1; i < branch_num; i++) |
| { |
| unsigned int lo, hi; |
| tree cs = gimple_switch_label (swtch, i); |
| tree label = CASE_LABEL (cs); |
| edge e = find_edge (switch_bb, label_to_block (label)); |
| for (k = 0; k < count; k++) |
| if (e == test[k].target_edge) |
| break; |
| |
| if (k == count) |
| { |
| gcc_checking_assert (count < MAX_CASE_BIT_TESTS); |
| test[k].mask = wi::zero (prec); |
| test[k].target_edge = e; |
| test[k].label = label; |
| test[k].bits = 1; |
| count++; |
| } |
| else |
| test[k].bits++; |
| |
| lo = tree_to_uhwi (int_const_binop (MINUS_EXPR, |
| CASE_LOW (cs), minval)); |
| if (CASE_HIGH (cs) == NULL_TREE) |
| hi = lo; |
| else |
| hi = tree_to_uhwi (int_const_binop (MINUS_EXPR, |
| CASE_HIGH (cs), 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_bb_for_speed_p (gimple_bb (swtch)); |
| 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; |
| } |
| } |
| |
| /* We generate two jumps to the default case label. |
| Split the default edge, so that we don't have to do any PHI node |
| updating. */ |
| new_default_bb = split_edge (default_edge); |
| |
| if (update_dom) |
| { |
| bbs_to_fix_dom.create (10); |
| bbs_to_fix_dom.quick_push (switch_bb); |
| bbs_to_fix_dom.quick_push (default_bb); |
| bbs_to_fix_dom.quick_push (new_default_bb); |
| } |
| |
| /* Now build the test-and-branch code. */ |
| |
| gsi = gsi_last_bb (switch_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); |
| new_bb = hoist_edge_and_branch_if_true (&gsi, tmp, default_edge, update_dom); |
| if (update_dom) |
| bbs_to_fix_dom.quick_push (new_bb); |
| gcc_assert (gimple_bb (swtch) == new_bb); |
| gsi = gsi_last_bb (new_bb); |
| |
| /* Any blocks dominated by the GIMPLE_SWITCH, but that are not successors |
| of NEW_BB, are still immediately dominated by SWITCH_BB. Make it so. */ |
| if (update_dom) |
| { |
| vec<basic_block> dom_bbs; |
| basic_block dom_son; |
| |
| dom_bbs = get_dominated_by (CDI_DOMINATORS, new_bb); |
| FOR_EACH_VEC_ELT (dom_bbs, i, dom_son) |
| { |
| edge e = find_edge (new_bb, dom_son); |
| if (e && single_pred_p (e->dest)) |
| continue; |
| set_immediate_dominator (CDI_DOMINATORS, dom_son, switch_bb); |
| bbs_to_fix_dom.safe_push (dom_son); |
| } |
| dom_bbs.release (); |
| } |
| |
| /* 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_edge, |
| update_dom); |
| if (update_dom) |
| bbs_to_fix_dom.safe_push (new_bb); |
| gcc_assert (gimple_bb (swtch) == new_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), new_default_bb, EDGE_FALLTHRU); |
| |
| /* The GIMPLE_SWITCH is now redundant. */ |
| gsi_remove (&gsi, true); |
| |
| if (update_dom) |
| { |
| /* Fix up the dominator tree. */ |
| iterate_fix_dominators (CDI_DOMINATORS, bbs_to_fix_dom, true); |
| bbs_to_fix_dom.release (); |
| } |
| } |
| |
| /* |
| Switch initialization conversion |
| |
| The following pass changes simple initializations of scalars in a switch |
| statement into initializations from a static array. Obviously, the values |
| must be constant and known at compile time and a default branch must be |
| provided. For example, the following code: |
| |
| int a,b; |
| |
| switch (argc) |
| { |
| case 1: |
| case 2: |
| a_1 = 8; |
| b_1 = 6; |
| break; |
| case 3: |
| a_2 = 9; |
| b_2 = 5; |
| break; |
| case 12: |
| a_3 = 10; |
| b_3 = 4; |
| break; |
| default: |
| a_4 = 16; |
| b_4 = 1; |
| break; |
| } |
| a_5 = PHI <a_1, a_2, a_3, a_4> |
| b_5 = PHI <b_1, b_2, b_3, b_4> |
| |
| |
| is changed into: |
| |
| static const int = CSWTCH01[] = {6, 6, 5, 1, 1, 1, 1, 1, 1, 1, 1, 4}; |
| static const int = CSWTCH02[] = {8, 8, 9, 16, 16, 16, 16, 16, 16, 16, |
| 16, 16, 10}; |
| |
| if (((unsigned) argc) - 1 < 11) |
| { |
| a_6 = CSWTCH02[argc - 1]; |
| b_6 = CSWTCH01[argc - 1]; |
| } |
| else |
| { |
| a_7 = 16; |
| b_7 = 1; |
| } |
| a_5 = PHI <a_6, a_7> |
| b_b = PHI <b_6, b_7> |
| |
| There are further constraints. Specifically, the range of values across all |
| case labels must not be bigger than SWITCH_CONVERSION_BRANCH_RATIO (default |
| eight) times the number of the actual switch branches. |
| |
| This transformation was contributed by Martin Jambor, see this e-mail: |
| http://gcc.gnu.org/ml/gcc-patches/2008-07/msg00011.html */ |
| |
| /* The main structure of the pass. */ |
| struct switch_conv_info |
| { |
| /* The expression used to decide the switch branch. */ |
| tree index_expr; |
| |
| /* The following integer constants store the minimum and maximum value |
| covered by the case labels. */ |
| tree range_min; |
| tree range_max; |
| |
| /* The difference between the above two numbers. Stored here because it |
| is used in all the conversion heuristics, as well as for some of the |
| transformation, and it is expensive to re-compute it all the time. */ |
| tree range_size; |
| |
| /* Basic block that contains the actual GIMPLE_SWITCH. */ |
| basic_block switch_bb; |
| |
| /* Basic block that is the target of the default case. */ |
| basic_block default_bb; |
| |
| /* The single successor block of all branches out of the GIMPLE_SWITCH, |
| if such a block exists. Otherwise NULL. */ |
| basic_block final_bb; |
| |
| /* The probability of the default edge in the replaced switch. */ |
| int default_prob; |
| |
| /* The count of the default edge in the replaced switch. */ |
| gcov_type default_count; |
| |
| /* Combined count of all other (non-default) edges in the replaced switch. */ |
| gcov_type other_count; |
| |
| /* Number of phi nodes in the final bb (that we'll be replacing). */ |
| int phi_count; |
| |
| /* Array of default values, in the same order as phi nodes. */ |
| tree *default_values; |
| |
| /* Constructors of new static arrays. */ |
| vec<constructor_elt, va_gc> **constructors; |
| |
| /* Array of ssa names that are initialized with a value from a new static |
| array. */ |
| tree *target_inbound_names; |
| |
| /* Array of ssa names that are initialized with the default value if the |
| switch expression is out of range. */ |
| tree *target_outbound_names; |
| |
| /* The first load statement that loads a temporary from a new static array. |
| */ |
| gimple *arr_ref_first; |
| |
| /* The last load statement that loads a temporary from a new static array. */ |
| gimple *arr_ref_last; |
| |
| /* String reason why the case wasn't a good candidate that is written to the |
| dump file, if there is one. */ |
| const char *reason; |
| |
| /* Parameters for expand_switch_using_bit_tests. Should be computed |
| the same way as in expand_case. */ |
| unsigned int uniq; |
| unsigned int count; |
| }; |
| |
| /* Collect information about GIMPLE_SWITCH statement SWTCH into INFO. */ |
| |
| static void |
| collect_switch_conv_info (gswitch *swtch, struct switch_conv_info *info) |
| { |
| unsigned int branch_num = gimple_switch_num_labels (swtch); |
| tree min_case, max_case; |
| unsigned int count, i; |
| edge e, e_default; |
| edge_iterator ei; |
| |
| memset (info, 0, sizeof (*info)); |
| |
| /* The gimplifier has already sorted the cases by CASE_LOW and ensured there |
| is a default label which is the first in the vector. |
| Collect the bits we can deduce from the CFG. */ |
| info->index_expr = gimple_switch_index (swtch); |
| info->switch_bb = gimple_bb (swtch); |
| info->default_bb = |
| label_to_block (CASE_LABEL (gimple_switch_default_label (swtch))); |
| e_default = find_edge (info->switch_bb, info->default_bb); |
| info->default_prob = e_default->probability; |
| info->default_count = e_default->count; |
| FOR_EACH_EDGE (e, ei, info->switch_bb->succs) |
| if (e != e_default) |
| info->other_count += e->count; |
| |
| /* See if there is one common successor block for all branch |
| targets. If it exists, record it in FINAL_BB. |
| Start with the destination of the default case as guess |
| or its destination in case it is a forwarder block. */ |
| if (! single_pred_p (e_default->dest)) |
| info->final_bb = e_default->dest; |
| else if (single_succ_p (e_default->dest) |
| && ! single_pred_p (single_succ (e_default->dest))) |
| info->final_bb = single_succ (e_default->dest); |
| /* Require that all switch destinations are either that common |
| FINAL_BB or a forwarder to it. */ |
| if (info->final_bb) |
| FOR_EACH_EDGE (e, ei, info->switch_bb->succs) |
| { |
| if (e->dest == info->final_bb) |
| continue; |
| |
| if (single_pred_p (e->dest) |
| && single_succ_p (e->dest) |
| && single_succ (e->dest) == info->final_bb) |
| continue; |
| |
| info->final_bb = NULL; |
| break; |
| } |
| |
| /* Get upper and lower bounds of case values, and the covered range. */ |
| min_case = gimple_switch_label (swtch, 1); |
| max_case = gimple_switch_label (swtch, branch_num - 1); |
| |
| info->range_min = CASE_LOW (min_case); |
| if (CASE_HIGH (max_case) != NULL_TREE) |
| info->range_max = CASE_HIGH (max_case); |
| else |
| info->range_max = CASE_LOW (max_case); |
| |
| info->range_size = |
| int_const_binop (MINUS_EXPR, info->range_max, info->range_min); |
| |
| /* Get a count of the number of case labels. Single-valued case labels |
| simply count as one, but a case range counts double, since it may |
| require two compares if it gets lowered as a branching tree. */ |
| count = 0; |
| for (i = 1; i < branch_num; i++) |
| { |
| tree elt = gimple_switch_label (swtch, i); |
| count++; |
| if (CASE_HIGH (elt) |
| && ! tree_int_cst_equal (CASE_LOW (elt), CASE_HIGH (elt))) |
| count++; |
| } |
| info->count = 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. */ |
| info->uniq = EDGE_COUNT (gimple_bb (swtch)->succs) - 1; |
| } |
| |
| /* Checks whether the range given by individual case statements of the SWTCH |
| switch statement isn't too big and whether the number of branches actually |
| satisfies the size of the new array. */ |
| |
| static bool |
| check_range (struct switch_conv_info *info) |
| { |
| gcc_assert (info->range_size); |
| if (!tree_fits_uhwi_p (info->range_size)) |
| { |
| info->reason = "index range way too large or otherwise unusable"; |
| return false; |
| } |
| |
| if (tree_to_uhwi (info->range_size) |
| > ((unsigned) info->count * SWITCH_CONVERSION_BRANCH_RATIO)) |
| { |
| info->reason = "the maximum range-branch ratio exceeded"; |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /* Checks whether all but the FINAL_BB basic blocks are empty. */ |
| |
| static bool |
| check_all_empty_except_final (struct switch_conv_info *info) |
| { |
| edge e; |
| edge_iterator ei; |
| |
| FOR_EACH_EDGE (e, ei, info->switch_bb->succs) |
| { |
| if (e->dest == info->final_bb) |
| continue; |
| |
| if (!empty_block_p (e->dest)) |
| { |
| info->reason = "bad case - a non-final BB not empty"; |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| /* This function checks whether all required values in phi nodes in final_bb |
| are constants. Required values are those that correspond to a basic block |
| which is a part of the examined switch statement. It returns true if the |
| phi nodes are OK, otherwise false. */ |
| |
| static bool |
| check_final_bb (struct switch_conv_info *info) |
| { |
| gphi_iterator gsi; |
| |
| info->phi_count = 0; |
| for (gsi = gsi_start_phis (info->final_bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi = gsi.phi (); |
| unsigned int i; |
| |
| info->phi_count++; |
| |
| for (i = 0; i < gimple_phi_num_args (phi); i++) |
| { |
| basic_block bb = gimple_phi_arg_edge (phi, i)->src; |
| |
| if (bb == info->switch_bb |
| || (single_pred_p (bb) && single_pred (bb) == info->switch_bb)) |
| { |
| tree reloc, val; |
| |
| val = gimple_phi_arg_def (phi, i); |
| if (!is_gimple_ip_invariant (val)) |
| { |
| info->reason = "non-invariant value from a case"; |
| return false; /* Non-invariant argument. */ |
| } |
| reloc = initializer_constant_valid_p (val, TREE_TYPE (val)); |
| if ((flag_pic && reloc != null_pointer_node) |
| || (!flag_pic && reloc == NULL_TREE)) |
| { |
| if (reloc) |
| info->reason |
| = "value from a case would need runtime relocations"; |
| else |
| info->reason |
| = "value from a case is not a valid initializer"; |
| return false; |
| } |
| } |
| } |
| } |
| |
| return true; |
| } |
| |
| /* The following function allocates default_values, target_{in,out}_names and |
| constructors arrays. The last one is also populated with pointers to |
| vectors that will become constructors of new arrays. */ |
| |
| static void |
| create_temp_arrays (struct switch_conv_info *info) |
| { |
| int i; |
| |
| info->default_values = XCNEWVEC (tree, info->phi_count * 3); |
| /* ??? Macros do not support multi argument templates in their |
| argument list. We create a typedef to work around that problem. */ |
| typedef vec<constructor_elt, va_gc> *vec_constructor_elt_gc; |
| info->constructors = XCNEWVEC (vec_constructor_elt_gc, info->phi_count); |
| info->target_inbound_names = info->default_values + info->phi_count; |
| info->target_outbound_names = info->target_inbound_names + info->phi_count; |
| for (i = 0; i < info->phi_count; i++) |
| vec_alloc (info->constructors[i], tree_to_uhwi (info->range_size) + 1); |
| } |
| |
| /* Free the arrays created by create_temp_arrays(). The vectors that are |
| created by that function are not freed here, however, because they have |
| already become constructors and must be preserved. */ |
| |
| static void |
| free_temp_arrays (struct switch_conv_info *info) |
| { |
| XDELETEVEC (info->constructors); |
| XDELETEVEC (info->default_values); |
| } |
| |
| /* Populate the array of default values in the order of phi nodes. |
| DEFAULT_CASE is the CASE_LABEL_EXPR for the default switch branch. */ |
| |
| static void |
| gather_default_values (tree default_case, struct switch_conv_info *info) |
| { |
| gphi_iterator gsi; |
| basic_block bb = label_to_block (CASE_LABEL (default_case)); |
| edge e; |
| int i = 0; |
| |
| gcc_assert (CASE_LOW (default_case) == NULL_TREE); |
| |
| if (bb == info->final_bb) |
| e = find_edge (info->switch_bb, bb); |
| else |
| e = single_succ_edge (bb); |
| |
| for (gsi = gsi_start_phis (info->final_bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi = gsi.phi (); |
| tree val = PHI_ARG_DEF_FROM_EDGE (phi, e); |
| gcc_assert (val); |
| info->default_values[i++] = val; |
| } |
| } |
| |
| /* The following function populates the vectors in the constructors array with |
| future contents of the static arrays. The vectors are populated in the |
| order of phi nodes. SWTCH is the switch statement being converted. */ |
| |
| static void |
| build_constructors (gswitch *swtch, struct switch_conv_info *info) |
| { |
| unsigned i, branch_num = gimple_switch_num_labels (swtch); |
| tree pos = info->range_min; |
| |
| for (i = 1; i < branch_num; i++) |
| { |
| tree cs = gimple_switch_label (swtch, i); |
| basic_block bb = label_to_block (CASE_LABEL (cs)); |
| edge e; |
| tree high; |
| gphi_iterator gsi; |
| int j; |
| |
| if (bb == info->final_bb) |
| e = find_edge (info->switch_bb, bb); |
| else |
| e = single_succ_edge (bb); |
| gcc_assert (e); |
| |
| while (tree_int_cst_lt (pos, CASE_LOW (cs))) |
| { |
| int k; |
| for (k = 0; k < info->phi_count; k++) |
| { |
| constructor_elt elt; |
| |
| elt.index = int_const_binop (MINUS_EXPR, pos, info->range_min); |
| elt.value |
| = unshare_expr_without_location (info->default_values[k]); |
| info->constructors[k]->quick_push (elt); |
| } |
| |
| pos = int_const_binop (PLUS_EXPR, pos, |
| build_int_cst (TREE_TYPE (pos), 1)); |
| } |
| gcc_assert (tree_int_cst_equal (pos, CASE_LOW (cs))); |
| |
| j = 0; |
| if (CASE_HIGH (cs)) |
| high = CASE_HIGH (cs); |
| else |
| high = CASE_LOW (cs); |
| for (gsi = gsi_start_phis (info->final_bb); |
| !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi = gsi.phi (); |
| tree val = PHI_ARG_DEF_FROM_EDGE (phi, e); |
| tree low = CASE_LOW (cs); |
| pos = CASE_LOW (cs); |
| |
| do |
| { |
| constructor_elt elt; |
| |
| elt.index = int_const_binop (MINUS_EXPR, pos, info->range_min); |
| elt.value = unshare_expr_without_location (val); |
| info->constructors[j]->quick_push (elt); |
| |
| pos = int_const_binop (PLUS_EXPR, pos, |
| build_int_cst (TREE_TYPE (pos), 1)); |
| } while (!tree_int_cst_lt (high, pos) |
| && tree_int_cst_lt (low, pos)); |
| j++; |
| } |
| } |
| } |
| |
| /* If all values in the constructor vector are the same, return the value. |
| Otherwise return NULL_TREE. Not supposed to be called for empty |
| vectors. */ |
| |
| static tree |
| constructor_contains_same_values_p (vec<constructor_elt, va_gc> *vec) |
| { |
| unsigned int i; |
| tree prev = NULL_TREE; |
| constructor_elt *elt; |
| |
| FOR_EACH_VEC_SAFE_ELT (vec, i, elt) |
| { |
| if (!prev) |
| prev = elt->value; |
| else if (!operand_equal_p (elt->value, prev, OEP_ONLY_CONST)) |
| return NULL_TREE; |
| } |
| return prev; |
| } |
| |
| /* Return type which should be used for array elements, either TYPE's |
| main variant or, for integral types, some smaller integral type |
| that can still hold all the constants. */ |
| |
| static tree |
| array_value_type (gswitch *swtch, tree type, int num, |
| struct switch_conv_info *info) |
| { |
| unsigned int i, len = vec_safe_length (info->constructors[num]); |
| constructor_elt *elt; |
| machine_mode mode; |
| int sign = 0; |
| tree smaller_type; |
| |
| /* Types with alignments greater than their size can reach here, e.g. out of |
| SRA. We couldn't use these as an array component type so get back to the |
| main variant first, which, for our purposes, is fine for other types as |
| well. */ |
| |
| type = TYPE_MAIN_VARIANT (type); |
| |
| if (!INTEGRAL_TYPE_P (type)) |
| return type; |
| |
| mode = GET_CLASS_NARROWEST_MODE (GET_MODE_CLASS (TYPE_MODE (type))); |
| if (GET_MODE_SIZE (TYPE_MODE (type)) <= GET_MODE_SIZE (mode)) |
| return type; |
| |
| if (len < (optimize_bb_for_size_p (gimple_bb (swtch)) ? 2 : 32)) |
| return type; |
| |
| FOR_EACH_VEC_SAFE_ELT (info->constructors[num], i, elt) |
| { |
| wide_int cst; |
| |
| if (TREE_CODE (elt->value) != INTEGER_CST) |
| return type; |
| |
| cst = elt->value; |
| while (1) |
| { |
| unsigned int prec = GET_MODE_BITSIZE (mode); |
| if (prec > HOST_BITS_PER_WIDE_INT) |
| return type; |
| |
| if (sign >= 0 && cst == wi::zext (cst, prec)) |
| { |
| if (sign == 0 && cst == wi::sext (cst, prec)) |
| break; |
| sign = 1; |
| break; |
| } |
| if (sign <= 0 && cst == wi::sext (cst, prec)) |
| { |
| sign = -1; |
| break; |
| } |
| |
| if (sign == 1) |
| sign = 0; |
| |
| mode = GET_MODE_WIDER_MODE (mode); |
| if (mode == VOIDmode |
| || GET_MODE_SIZE (mode) >= GET_MODE_SIZE (TYPE_MODE (type))) |
| return type; |
| } |
| } |
| |
| if (sign == 0) |
| sign = TYPE_UNSIGNED (type) ? 1 : -1; |
| smaller_type = lang_hooks.types.type_for_mode (mode, sign >= 0); |
| if (GET_MODE_SIZE (TYPE_MODE (type)) |
| <= GET_MODE_SIZE (TYPE_MODE (smaller_type))) |
| return type; |
| |
| return smaller_type; |
| } |
| |
| /* Create an appropriate array type and declaration and assemble a static array |
| variable. Also create a load statement that initializes the variable in |
| question with a value from the static array. SWTCH is the switch statement |
| being converted, NUM is the index to arrays of constructors, default values |
| and target SSA names for this particular array. ARR_INDEX_TYPE is the type |
| of the index of the new array, PHI is the phi node of the final BB that |
| corresponds to the value that will be loaded from the created array. TIDX |
| is an ssa name of a temporary variable holding the index for loads from the |
| new array. */ |
| |
| static void |
| build_one_array (gswitch *swtch, int num, tree arr_index_type, |
| gphi *phi, tree tidx, struct switch_conv_info *info) |
| { |
| tree name, cst; |
| gimple *load; |
| gimple_stmt_iterator gsi = gsi_for_stmt (swtch); |
| location_t loc = gimple_location (swtch); |
| |
| gcc_assert (info->default_values[num]); |
| |
| name = copy_ssa_name (PHI_RESULT (phi)); |
| info->target_inbound_names[num] = name; |
| |
| cst = constructor_contains_same_values_p (info->constructors[num]); |
| if (cst) |
| load = gimple_build_assign (name, cst); |
| else |
| { |
| tree array_type, ctor, decl, value_type, fetch, default_type; |
| |
| default_type = TREE_TYPE (info->default_values[num]); |
| value_type = array_value_type (swtch, default_type, num, info); |
| array_type = build_array_type (value_type, arr_index_type); |
| if (default_type != value_type) |
| { |
| unsigned int i; |
| constructor_elt *elt; |
| |
| FOR_EACH_VEC_SAFE_ELT (info->constructors[num], i, elt) |
| elt->value = fold_convert (value_type, elt->value); |
| } |
| ctor = build_constructor (array_type, info->constructors[num]); |
| TREE_CONSTANT (ctor) = true; |
| TREE_STATIC (ctor) = true; |
| |
| decl = build_decl (loc, VAR_DECL, NULL_TREE, array_type); |
| TREE_STATIC (decl) = 1; |
| DECL_INITIAL (decl) = ctor; |
| |
| DECL_NAME (decl) = create_tmp_var_name ("CSWTCH"); |
| DECL_ARTIFICIAL (decl) = 1; |
| DECL_IGNORED_P (decl) = 1; |
| TREE_CONSTANT (decl) = 1; |
| TREE_READONLY (decl) = 1; |
| DECL_IGNORED_P (decl) = 1; |
| varpool_node::finalize_decl (decl); |
| |
| fetch = build4 (ARRAY_REF, value_type, decl, tidx, NULL_TREE, |
| NULL_TREE); |
| if (default_type != value_type) |
| { |
| fetch = fold_convert (default_type, fetch); |
| fetch = force_gimple_operand_gsi (&gsi, fetch, true, NULL_TREE, |
| true, GSI_SAME_STMT); |
| } |
| load = gimple_build_assign (name, fetch); |
| } |
| |
| gsi_insert_before (&gsi, load, GSI_SAME_STMT); |
| update_stmt (load); |
| info->arr_ref_last = load; |
| } |
| |
| /* Builds and initializes static arrays initialized with values gathered from |
| the SWTCH switch statement. Also creates statements that load values from |
| them. */ |
| |
| static void |
| build_arrays (gswitch *swtch, struct switch_conv_info *info) |
| { |
| tree arr_index_type; |
| tree tidx, sub, utype; |
| gimple *stmt; |
| gimple_stmt_iterator gsi; |
| gphi_iterator gpi; |
| int i; |
| location_t loc = gimple_location (swtch); |
| |
| gsi = gsi_for_stmt (swtch); |
| |
| /* Make sure we do not generate arithmetics in a subrange. */ |
| utype = TREE_TYPE (info->index_expr); |
| if (TREE_TYPE (utype)) |
| utype = lang_hooks.types.type_for_mode (TYPE_MODE (TREE_TYPE (utype)), 1); |
| else |
| utype = lang_hooks.types.type_for_mode (TYPE_MODE (utype), 1); |
| |
| arr_index_type = build_index_type (info->range_size); |
| tidx = make_ssa_name (utype); |
| sub = fold_build2_loc (loc, MINUS_EXPR, utype, |
| fold_convert_loc (loc, utype, info->index_expr), |
| fold_convert_loc (loc, utype, info->range_min)); |
| sub = force_gimple_operand_gsi (&gsi, sub, |
| false, NULL, true, GSI_SAME_STMT); |
| stmt = gimple_build_assign (tidx, sub); |
| |
| gsi_insert_before (&gsi, stmt, GSI_SAME_STMT); |
| update_stmt (stmt); |
| info->arr_ref_first = stmt; |
| |
| for (gpi = gsi_start_phis (info->final_bb), i = 0; |
| !gsi_end_p (gpi); gsi_next (&gpi), i++) |
| build_one_array (swtch, i, arr_index_type, gpi.phi (), tidx, info); |
| } |
| |
| /* Generates and appropriately inserts loads of default values at the position |
| given by BSI. Returns the last inserted statement. */ |
| |
| static gassign * |
| gen_def_assigns (gimple_stmt_iterator *gsi, struct switch_conv_info *info) |
| { |
| int i; |
| gassign *assign = NULL; |
| |
| for (i = 0; i < info->phi_count; i++) |
| { |
| tree name = copy_ssa_name (info->target_inbound_names[i]); |
| info->target_outbound_names[i] = name; |
| assign = gimple_build_assign (name, info->default_values[i]); |
| gsi_insert_before (gsi, assign, GSI_SAME_STMT); |
| update_stmt (assign); |
| } |
| return assign; |
| } |
| |
| /* Deletes the unused bbs and edges that now contain the switch statement and |
| its empty branch bbs. BBD is the now dead BB containing the original switch |
| statement, FINAL is the last BB of the converted switch statement (in terms |
| of succession). */ |
| |
| static void |
| prune_bbs (basic_block bbd, basic_block final) |
| { |
| edge_iterator ei; |
| edge e; |
| |
| for (ei = ei_start (bbd->succs); (e = ei_safe_edge (ei)); ) |
| { |
| basic_block bb; |
| bb = e->dest; |
| remove_edge (e); |
| if (bb != final) |
| delete_basic_block (bb); |
| } |
| delete_basic_block (bbd); |
| } |
| |
| /* Add values to phi nodes in final_bb for the two new edges. E1F is the edge |
| from the basic block loading values from an array and E2F from the basic |
| block loading default values. BBF is the last switch basic block (see the |
| bbf description in the comment below). */ |
| |
| static void |
| fix_phi_nodes (edge e1f, edge e2f, basic_block bbf, |
| struct switch_conv_info *info) |
| { |
| gphi_iterator gsi; |
| int i; |
| |
| for (gsi = gsi_start_phis (bbf), i = 0; |
| !gsi_end_p (gsi); gsi_next (&gsi), i++) |
| { |
| gphi *phi = gsi.phi (); |
| add_phi_arg (phi, info->target_inbound_names[i], e1f, UNKNOWN_LOCATION); |
| add_phi_arg (phi, info->target_outbound_names[i], e2f, UNKNOWN_LOCATION); |
| } |
| } |
| |
| /* Creates a check whether the switch expression value actually falls into the |
| range given by all the cases. If it does not, the temporaries are loaded |
| with default values instead. SWTCH is the switch statement being converted. |
| |
| bb0 is the bb with the switch statement, however, we'll end it with a |
| condition instead. |
| |
| bb1 is the bb to be used when the range check went ok. It is derived from |
| the switch BB |
| |
| bb2 is the bb taken when the expression evaluated outside of the range |
| covered by the created arrays. It is populated by loads of default |
| values. |
| |
| bbF is a fall through for both bb1 and bb2 and contains exactly what |
| originally followed the switch statement. |
| |
| bbD contains the switch statement (in the end). It is unreachable but we |
| still need to strip off its edges. |
| */ |
| |
| static void |
| gen_inbound_check (gswitch *swtch, struct switch_conv_info *info) |
| { |
| tree label_decl1 = create_artificial_label (UNKNOWN_LOCATION); |
| tree label_decl2 = create_artificial_label (UNKNOWN_LOCATION); |
| tree label_decl3 = create_artificial_label (UNKNOWN_LOCATION); |
| glabel *label1, *label2, *label3; |
| tree utype, tidx; |
| tree bound; |
| |
| gcond *cond_stmt; |
| |
| gassign *last_assign; |
| gimple_stmt_iterator gsi; |
| basic_block bb0, bb1, bb2, bbf, bbd; |
| edge e01, e02, e21, e1d, e1f, e2f; |
| location_t loc = gimple_location (swtch); |
| |
| gcc_assert (info->default_values); |
| |
| bb0 = gimple_bb (swtch); |
| |
| tidx = gimple_assign_lhs (info->arr_ref_first); |
| utype = TREE_TYPE (tidx); |
| |
| /* (end of) block 0 */ |
| gsi = gsi_for_stmt (info->arr_ref_first); |
| gsi_next (&gsi); |
| |
| bound = fold_convert_loc (loc, utype, info->range_size); |
| cond_stmt = gimple_build_cond (LE_EXPR, tidx, bound, NULL_TREE, NULL_TREE); |
| gsi_insert_before (&gsi, cond_stmt, GSI_SAME_STMT); |
| update_stmt (cond_stmt); |
| |
| /* block 2 */ |
| label2 = gimple_build_label (label_decl2); |
| gsi_insert_before (&gsi, label2, GSI_SAME_STMT); |
| last_assign = gen_def_assigns (&gsi, info); |
| |
| /* block 1 */ |
| label1 = gimple_build_label (label_decl1); |
| gsi_insert_before (&gsi, label1, GSI_SAME_STMT); |
| |
| /* block F */ |
| gsi = gsi_start_bb (info->final_bb); |
| label3 = gimple_build_label (label_decl3); |
| gsi_insert_before (&gsi, label3, GSI_SAME_STMT); |
| |
| /* cfg fix */ |
| e02 = split_block (bb0, cond_stmt); |
| bb2 = e02->dest; |
| |
| e21 = split_block (bb2, last_assign); |
| bb1 = e21->dest; |
| remove_edge (e21); |
| |
| e1d = split_block (bb1, info->arr_ref_last); |
| bbd = e1d->dest; |
| remove_edge (e1d); |
| |
| /* flags and profiles of the edge for in-range values */ |
| e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE); |
| e01->probability = REG_BR_PROB_BASE - info->default_prob; |
| e01->count = info->other_count; |
| |
| /* flags and profiles of the edge taking care of out-of-range values */ |
| e02->flags &= ~EDGE_FALLTHRU; |
| e02->flags |= EDGE_FALSE_VALUE; |
| e02->probability = info->default_prob; |
| e02->count = info->default_count; |
| |
| bbf = info->final_bb; |
| |
| e1f = make_edge (bb1, bbf, EDGE_FALLTHRU); |
| e1f->probability = REG_BR_PROB_BASE; |
| e1f->count = info->other_count; |
| |
| e2f = make_edge (bb2, bbf, EDGE_FALLTHRU); |
| e2f->probability = REG_BR_PROB_BASE; |
| e2f->count = info->default_count; |
| |
| /* frequencies of the new BBs */ |
| bb1->frequency = EDGE_FREQUENCY (e01); |
| bb2->frequency = EDGE_FREQUENCY (e02); |
| bbf->frequency = EDGE_FREQUENCY (e1f) + EDGE_FREQUENCY (e2f); |
| |
| /* Tidy blocks that have become unreachable. */ |
| prune_bbs (bbd, info->final_bb); |
| |
| /* Fixup the PHI nodes in bbF. */ |
| fix_phi_nodes (e1f, e2f, bbf, info); |
| |
| /* Fix the dominator tree, if it is available. */ |
| if (dom_info_available_p (CDI_DOMINATORS)) |
| { |
| vec<basic_block> bbs_to_fix_dom; |
| |
| set_immediate_dominator (CDI_DOMINATORS, bb1, bb0); |
| set_immediate_dominator (CDI_DOMINATORS, bb2, bb0); |
| if (! get_immediate_dominator (CDI_DOMINATORS, bbf)) |
| /* If bbD was the immediate dominator ... */ |
| set_immediate_dominator (CDI_DOMINATORS, bbf, bb0); |
| |
| bbs_to_fix_dom.create (4); |
| bbs_to_fix_dom.quick_push (bb0); |
| bbs_to_fix_dom.quick_push (bb1); |
| bbs_to_fix_dom.quick_push (bb2); |
| bbs_to_fix_dom.quick_push (bbf); |
| |
| iterate_fix_dominators (CDI_DOMINATORS, bbs_to_fix_dom, true); |
| bbs_to_fix_dom.release (); |
| } |
| } |
| |
| /* The following function is invoked on every switch statement (the current one |
| is given in SWTCH) and runs the individual phases of switch conversion on it |
| one after another until one fails or the conversion is completed. |
| Returns NULL on success, or a pointer to a string with the reason why the |
| conversion failed. */ |
| |
| static const char * |
| process_switch (gswitch *swtch) |
| { |
| struct switch_conv_info info; |
| |
| /* Group case labels so that we get the right results from the heuristics |
| that decide on the code generation approach for this switch. */ |
| group_case_labels_stmt (swtch); |
| |
| /* If this switch is now a degenerate case with only a default label, |
| there is nothing left for us to do. */ |
| if (gimple_switch_num_labels (swtch) < 2) |
| return "switch is a degenerate case"; |
| |
| collect_switch_conv_info (swtch, &info); |
| |
| /* No error markers should reach here (they should be filtered out |
| during gimplification). */ |
| gcc_checking_assert (TREE_TYPE (info.index_expr) != error_mark_node); |
| |
| /* A switch on a constant should have been optimized in tree-cfg-cleanup. */ |
| gcc_checking_assert (! TREE_CONSTANT (info.index_expr)); |
| |
| if (info.uniq <= MAX_CASE_BIT_TESTS) |
| { |
| if (expand_switch_using_bit_tests_p (info.range_size, |
| info.uniq, info.count, |
| optimize_bb_for_speed_p |
| (gimple_bb (swtch)))) |
| { |
| if (dump_file) |
| fputs (" expanding as bit test is preferable\n", dump_file); |
| emit_case_bit_tests (swtch, info.index_expr, info.range_min, |
| info.range_size, info.range_max); |
| loops_state_set (LOOPS_NEED_FIXUP); |
| return NULL; |
| } |
| |
| if (info.uniq <= 2) |
| /* This will be expanded as a decision tree in stmt.c:expand_case. */ |
| return " expanding as jumps is preferable"; |
| } |
| |
| /* If there is no common successor, we cannot do the transformation. */ |
| if (! info.final_bb) |
| return "no common successor to all case label target blocks found"; |
| |
| /* Check the case label values are within reasonable range: */ |
| if (!check_range (&info)) |
| { |
| gcc_assert (info.reason); |
| return info.reason; |
| } |
| |
| /* For all the cases, see whether they are empty, the assignments they |
| represent constant and so on... */ |
| if (! check_all_empty_except_final (&info)) |
| { |
| gcc_assert (info.reason); |
| return info.reason; |
| } |
| if (!check_final_bb (&info)) |
| { |
| gcc_assert (info.reason); |
| return info.reason; |
| } |
| |
| /* At this point all checks have passed and we can proceed with the |
| transformation. */ |
| |
| create_temp_arrays (&info); |
| gather_default_values (gimple_switch_default_label (swtch), &info); |
| build_constructors (swtch, &info); |
| |
| build_arrays (swtch, &info); /* Build the static arrays and assignments. */ |
| gen_inbound_check (swtch, &info); /* Build the bounds check. */ |
| |
| /* Cleanup: */ |
| free_temp_arrays (&info); |
| return NULL; |
| } |
| |
| /* The main function of the pass scans statements for switches and invokes |
| process_switch on them. */ |
| |
| namespace { |
| |
| 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 */ |
| }; |
| |
| class pass_convert_switch : public gimple_opt_pass |
| { |
| public: |
| pass_convert_switch (gcc::context *ctxt) |
| : gimple_opt_pass (pass_data_convert_switch, ctxt) |
| {} |
| |
| /* opt_pass methods: */ |
| virtual bool gate (function *) { return flag_tree_switch_conversion != 0; } |
| virtual unsigned int execute (function *); |
| |
| }; // class pass_convert_switch |
| |
| unsigned int |
| pass_convert_switch::execute (function *fun) |
| { |
| basic_block bb; |
| |
| FOR_EACH_BB_FN (bb, fun) |
| { |
| const char *failure_reason; |
| gimple *stmt = last_stmt (bb); |
| if (stmt && gimple_code (stmt) == GIMPLE_SWITCH) |
| { |
| if (dump_file) |
| { |
| 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); |
| } |
| |
| failure_reason = process_switch (as_a <gswitch *> (stmt)); |
| if (! failure_reason) |
| { |
| if (dump_file) |
| { |
| fputs ("Switch converted\n", dump_file); |
| fputs ("--------------------------------\n", dump_file); |
| } |
| |
| /* 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 (failure_reason, dump_file); |
| fputs ("\n--------------------------------\n", dump_file); |
| } |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| } // anon namespace |
| |
| gimple_opt_pass * |
| make_pass_convert_switch (gcc::context *ctxt) |
| { |
| return new pass_convert_switch (ctxt); |
| } |