| /* 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" |
| #include "alloc-pool.h" |
| #include "target.h" |
| #include "tree-into-ssa.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 = e_true->probability.invert (); |
| 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 -1; |
| if (d2->target_edge->count () > d1->target_edge->count ()) |
| return 1; |
| 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); |
| |
| /* 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. */ |
| profile_probability default_prob; |
| |
| /* The count of the default edge in the replaced switch. */ |
| profile_count default_count; |
| |
| /* Combined count of all other (non-default) edges in the replaced switch. */ |
| profile_count 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; |
| |
| /* VOP SSA_NAME. */ |
| tree target_vop; |
| |
| /* 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; |
| |
| /* True if default case is not used for any value between range_min and |
| range_max inclusive. */ |
| bool contiguous_range; |
| |
| /* True if default case does not have the required shape for other case |
| labels. */ |
| bool default_case_nonstandard; |
| |
| /* 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, e_first; |
| edge_iterator ei; |
| basic_block first; |
| |
| 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 (); |
| |
| /* 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->contiguous_range = true; |
| tree last = CASE_HIGH (min_case) ? CASE_HIGH (min_case) : info->range_min; |
| for (i = 2; i < branch_num; i++) |
| { |
| tree elt = gimple_switch_label (swtch, i); |
| if (wi::to_wide (last) + 1 != wi::to_wide (CASE_LOW (elt))) |
| { |
| info->contiguous_range = false; |
| break; |
| } |
| last = CASE_HIGH (elt) ? CASE_HIGH (elt) : CASE_LOW (elt); |
| } |
| |
| if (info->contiguous_range) |
| { |
| first = label_to_block (CASE_LABEL (gimple_switch_label (swtch, 1))); |
| e_first = find_edge (info->switch_bb, first); |
| } |
| else |
| { |
| first = info->default_bb; |
| e_first = e_default; |
| } |
| |
| /* 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 first non-default case |
| if the range is contiguous and default case otherwise as |
| guess or its destination in case it is a forwarder block. */ |
| if (! single_pred_p (e_first->dest)) |
| info->final_bb = e_first->dest; |
| else if (single_succ_p (e_first->dest) |
| && ! single_pred_p (single_succ (e_first->dest))) |
| info->final_bb = single_succ (e_first->dest); |
| /* Require that all switch destinations are either that common |
| FINAL_BB or a forwarder to it, except for the default |
| case if contiguous range. */ |
| 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; |
| |
| if (e == e_default && info->contiguous_range) |
| { |
| info->default_case_nonstandard = true; |
| continue; |
| } |
| |
| info->final_bb = NULL; |
| break; |
| } |
| |
| 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, e_default = find_edge (info->switch_bb, info->default_bb); |
| 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)) |
| { |
| if (info->contiguous_range && e == e_default) |
| { |
| info->default_case_nonstandard = true; |
| continue; |
| } |
| |
| 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 (gswitch *swtch, 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; |
| |
| if (virtual_operand_p (gimple_phi_result (phi))) |
| continue; |
| |
| 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 |
| && (!info->default_case_nonstandard |
| || empty_block_p (bb)))) |
| { |
| tree reloc, val; |
| const char *reason = NULL; |
| |
| val = gimple_phi_arg_def (phi, i); |
| if (!is_gimple_ip_invariant (val)) |
| reason = "non-invariant value from a case"; |
| else |
| { |
| reloc = initializer_constant_valid_p (val, TREE_TYPE (val)); |
| if ((flag_pic && reloc != null_pointer_node) |
| || (!flag_pic && reloc == NULL_TREE)) |
| { |
| if (reloc) |
| reason |
| = "value from a case would need runtime relocations"; |
| else |
| reason |
| = "value from a case is not a valid initializer"; |
| } |
| } |
| if (reason) |
| { |
| /* For contiguous range, we can allow non-constant |
| or one that needs relocation, as long as it is |
| only reachable from the default case. */ |
| if (bb == info->switch_bb) |
| bb = info->final_bb; |
| if (!info->contiguous_range || bb != info->default_bb) |
| { |
| info->reason = reason; |
| return false; |
| } |
| |
| unsigned int branch_num = gimple_switch_num_labels (swtch); |
| for (unsigned int i = 1; i < branch_num; i++) |
| { |
| tree lab = CASE_LABEL (gimple_switch_label (swtch, i)); |
| if (label_to_block (lab) == bb) |
| { |
| info->reason = reason; |
| return false; |
| } |
| } |
| info->default_case_nonstandard = true; |
| } |
| } |
| } |
| } |
| |
| 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 |
| if the range is non-contiguous or the default case has standard |
| structure, otherwise it is the first non-default case instead. */ |
| |
| 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 |
| || info->default_case_nonstandard); |
| |
| 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 (); |
| if (virtual_operand_p (gimple_phi_result (phi))) |
| continue; |
| 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; |
| tree pos_one = build_int_cst (TREE_TYPE (pos), 1); |
| |
| 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; |
| gcc_assert (!info->contiguous_range); |
| 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, pos_one); |
| } |
| 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 (); |
| if (virtual_operand_p (gimple_phi_result (phi))) |
| continue; |
| 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, pos_one); |
| } 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; |
| 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; |
| |
| scalar_int_mode type_mode = SCALAR_INT_TYPE_MODE (type); |
| scalar_int_mode mode = get_narrowest_mode (type_mode); |
| if (GET_MODE_SIZE (type_mode) <= 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 = wi::to_wide (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; |
| |
| if (!GET_MODE_WIDER_MODE (mode).exists (&mode) |
| || GET_MODE_SIZE (mode) >= GET_MODE_SIZE (type_mode)) |
| 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) |
| <= GET_MODE_SIZE (SCALAR_INT_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)) |
| { |
| gphi *phi = gpi.phi (); |
| if (!virtual_operand_p (gimple_phi_result (phi))) |
| build_one_array (swtch, i++, arr_index_type, phi, tidx, info); |
| else |
| { |
| edge e; |
| edge_iterator ei; |
| FOR_EACH_EDGE (e, ei, info->switch_bb->succs) |
| { |
| if (e->dest == info->final_bb) |
| break; |
| if (!info->default_case_nonstandard |
| || e->dest != info->default_bb) |
| { |
| e = single_succ_edge (e->dest); |
| break; |
| } |
| } |
| gcc_assert (e && e->dest == info->final_bb); |
| info->target_vop = PHI_ARG_DEF_FROM_EDGE (phi, e); |
| } |
| } |
| } |
| |
| /* 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, basic_block default_bb) |
| { |
| 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 && bb != default_bb) |
| 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)) |
| { |
| gphi *phi = gsi.phi (); |
| tree inbound, outbound; |
| if (virtual_operand_p (gimple_phi_result (phi))) |
| inbound = outbound = info->target_vop; |
| else |
| { |
| inbound = info->target_inbound_names[i]; |
| outbound = info->target_outbound_names[i++]; |
| } |
| add_phi_arg (phi, inbound, e1f, UNKNOWN_LOCATION); |
| if (!info->default_case_nonstandard) |
| add_phi_arg (phi, outbound, 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 = NULL; |
| gimple_stmt_iterator gsi; |
| basic_block bb0, bb1, bb2, bbf, bbd; |
| edge e01 = NULL, 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 */ |
| if (!info->default_case_nonstandard) |
| { |
| 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; |
| |
| if (info->default_case_nonstandard) |
| { |
| bb1 = bb2; |
| bb2 = info->default_bb; |
| e01 = e02; |
| e01->flags = EDGE_TRUE_VALUE; |
| e02 = make_edge (bb0, bb2, EDGE_FALSE_VALUE); |
| edge e_default = find_edge (bb1, bb2); |
| for (gphi_iterator gsi = gsi_start_phis (bb2); |
| !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi = gsi.phi (); |
| tree arg = PHI_ARG_DEF_FROM_EDGE (phi, e_default); |
| add_phi_arg (phi, arg, e02, |
| gimple_phi_arg_location_from_edge (phi, e_default)); |
| } |
| /* Partially fix the dominator tree, if it is available. */ |
| if (dom_info_available_p (CDI_DOMINATORS)) |
| redirect_immediate_dominators (CDI_DOMINATORS, bb1, bb0); |
| } |
| else |
| { |
| 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 */ |
| if (!info->default_case_nonstandard) |
| e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE); |
| e01->probability = info->default_prob.invert (); |
| |
| /* 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; |
| |
| bbf = info->final_bb; |
| |
| e1f = make_edge (bb1, bbf, EDGE_FALLTHRU); |
| e1f->probability = profile_probability::always (); |
| |
| if (info->default_case_nonstandard) |
| e2f = NULL; |
| else |
| { |
| e2f = make_edge (bb2, bbf, EDGE_FALLTHRU); |
| e2f->probability = profile_probability::always (); |
| } |
| |
| /* frequencies of the new BBs */ |
| bb1->count = e01->count (); |
| bb2->count = e02->count (); |
| if (!info->default_case_nonstandard) |
| bbf->count = e1f->count () + e2f->count (); |
| |
| /* Tidy blocks that have become unreachable. */ |
| prune_bbs (bbd, info->final_bb, |
| info->default_case_nonstandard ? info->default_bb : NULL); |
| |
| /* 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); |
| if (!info->default_case_nonstandard) |
| 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 (3 + (bb2 != bbf)); |
| bbs_to_fix_dom.quick_push (bb0); |
| bbs_to_fix_dom.quick_push (bb1); |
| if (bb2 != bbf) |
| 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 (swtch, &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 (info.default_case_nonstandard |
| ? gimple_switch_label (swtch, 1) |
| : 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); |
| } |
| |
| struct case_node |
| { |
| 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. */ |
| }; |
| |
| typedef case_node *case_node_ptr; |
| |
| static basic_block emit_case_nodes (basic_block, tree, case_node_ptr, |
| basic_block, tree, profile_probability, |
| tree, hash_map<tree, tree> *); |
| static bool node_has_low_bound (case_node_ptr, tree); |
| static bool node_has_high_bound (case_node_ptr, tree); |
| static bool node_is_bounded (case_node_ptr, tree); |
| |
| /* Return the smallest number of different values for which it is best to use a |
| jump-table instead of a tree of conditional branches. */ |
| |
| static unsigned int |
| case_values_threshold (void) |
| { |
| unsigned int threshold = PARAM_VALUE (PARAM_CASE_VALUES_THRESHOLD); |
| |
| if (threshold == 0) |
| threshold = targetm.case_values_threshold (); |
| |
| return threshold; |
| } |
| |
| /* Reset the aux field of all outgoing edges of basic block BB. */ |
| |
| static inline void |
| reset_out_edges_aux (basic_block bb) |
| { |
| edge e; |
| edge_iterator ei; |
| FOR_EACH_EDGE (e, ei, bb->succs) |
| e->aux = (void *) 0; |
| } |
| |
| /* Compute the number of case labels that correspond to each outgoing edge of |
| STMT. Record this information in the aux field of the edge. */ |
| |
| static inline void |
| compute_cases_per_edge (gswitch *stmt) |
| { |
| basic_block bb = gimple_bb (stmt); |
| reset_out_edges_aux (bb); |
| int ncases = gimple_switch_num_labels (stmt); |
| for (int i = ncases - 1; i >= 1; --i) |
| { |
| tree elt = gimple_switch_label (stmt, i); |
| tree lab = CASE_LABEL (elt); |
| basic_block case_bb = label_to_block_fn (cfun, lab); |
| edge case_edge = find_edge (bb, case_bb); |
| case_edge->aux = (void *) ((intptr_t) (case_edge->aux) + 1); |
| } |
| } |
| |
| /* 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. |
| |
| 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. */ |
| |
| 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) |
| { |
| 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; |
| } |
| |
| /* Dump ROOT, a list or tree of case nodes, to file. */ |
| |
| static void |
| dump_case_nodes (FILE *f, case_node *root, int indent_step, int indent_level) |
| { |
| if (root == 0) |
| return; |
| indent_level++; |
| |
| dump_case_nodes (f, root->left, indent_step, indent_level); |
| |
| 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)) |
| { |
| fprintf (f, " ... "); |
| print_dec (wi::to_wide (root->high), f, |
| TYPE_SIGN (TREE_TYPE (root->high))); |
| } |
| fputs ("\n", f); |
| |
| dump_case_nodes (f, root->right, indent_step, indent_level); |
| } |
| |
| /* Take an ordered list of case nodes |
| and transform them into a near optimal binary tree, |
| on the assumption that any target code selection value is as |
| likely as any other. |
| |
| The transformation is performed by splitting the ordered |
| list into two equal sections plus a pivot. The parts are |
| 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) |
| { |
| case_node_ptr np; |
| |
| np = *head; |
| if (np) |
| { |
| int i = 0; |
| int ranges = 0; |
| case_node_ptr *npp; |
| case_node_ptr left; |
| |
| /* Count the number of entries on branch. Also count the ranges. */ |
| |
| while (np) |
| { |
| if (!tree_int_cst_equal (np->low, np->high)) |
| ranges++; |
| |
| i++; |
| np = np->right; |
| } |
| |
| if (i > 2) |
| { |
| /* Split this list if it is long enough for that to help. */ |
| npp = head; |
| left = *npp; |
| |
| /* If there are just three nodes, split at the middle one. */ |
| if (i == 3) |
| npp = &(*npp)->right; |
| else |
| { |
| /* Find the place in the list that bisects the list's total cost, |
| where ranges count as 2. |
| Here I gets half the total cost. */ |
| i = (i + ranges + 1) / 2; |
| while (1) |
| { |
| /* Skip nodes while their cost does not reach that amount. */ |
| if (!tree_int_cst_equal ((*npp)->low, (*npp)->high)) |
| i--; |
| i--; |
| if (i <= 0) |
| break; |
| npp = &(*npp)->right; |
| } |
| } |
| *head = np = *npp; |
| *npp = 0; |
| np->parent = parent; |
| np->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; |
| } |
| 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->right->parent = np; |
| (*head)->subtree_prob += np->right->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. */ |
| |
| static bool |
| expand_switch_as_decision_tree_p (tree range, |
| unsigned int uniq ATTRIBUTE_UNUSED, |
| unsigned int count) |
| { |
| 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; |
| |
| return false; |
| } |
| |
| 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 (); |
| |
| tree *definition = phi_mapping->get (gimple_phi_result (phi)); |
| if (definition) |
| add_phi_arg (phi, *definition, e, UNKNOWN_LOCATION); |
| } |
| } |
| |
| |
| /* 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) |
| { |
| 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. */ |
| |
| 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) |
| { |
| 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); |
| } |
| |
| basic_block bb = gimple_bb (s); |
| 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); |
| |
| bb = emit_case_nodes (bb, index_expr, case_list, default_bb, default_label, |
| default_prob, index_type, phi_mapping); |
| |
| if (bb) |
| emit_jump (bb, default_bb, phi_mapping); |
| |
| /* Remove all edges and do just an edge that will reach default_bb. */ |
| gsi = gsi_last_bb (gimple_bb (s)); |
| gsi_remove (&gsi, true); |
| } |
| |
| static void |
| record_phi_operand_mapping (const vec<basic_block> bbs, basic_block switch_bb, |
| hash_map <tree, tree> *map) |
| { |
| /* Record all PHI nodes that have to be fixed after conversion. */ |
| for (unsigned i = 0; i < bbs.length (); i++) |
| { |
| basic_block bb = bbs[i]; |
| |
| gphi_iterator gsi; |
| for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi = gsi.phi (); |
| |
| 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; |
| } |
| } |
| } |
| } |
| } |
| |
| /* Attempt to expand gimple switch STMT to a decision tree. */ |
| |
| 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); |
| |
| hash_map<tree, tree> phi_mapping; |
| auto_vec<basic_block> case_bbs; |
| |
| /* 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; |
| |
| /* A pool for case nodes. */ |
| object_allocator<case_node> case_node_pool ("struct case_node pool"); |
| |
| /* cleanup_tree_cfg removes all SWITCH_EXPR with their index |
| expressions being INTEGER_CST. */ |
| gcc_assert (TREE_CODE (index_expr) != INTEGER_CST); |
| |
| if (ncases == 1) |
| return false; |
| |
| /* 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)); |
| |
| /* Compute span of values. */ |
| range = fold_build2 (MINUS_EXPR, index_type, maxval, minval); |
| |
| /* 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); |
| |
| 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); |
| |
| /* 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)); |
| |
| 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); |
| |
| case_bbs.safe_push (case_bb); |
| } |
| reset_out_edges_aux (bb); |
| record_phi_operand_mapping (case_bbs, bb, &phi_mapping); |
| |
| /* 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); |
| |
| /* Decide how to expand this switch. |
| The two options at this point are a dispatch table (casesi or |
| tablejump) or a decision tree. */ |
| |
| 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 false; |
| } |
| |
| /* The main function of the pass scans statements for switches and invokes |
| process_switch on them. */ |
| |
| namespace { |
| |
| const pass_data pass_data_lower_switch = |
| { |
| GIMPLE_PASS, /* type */ |
| "switchlower", /* name */ |
| OPTGROUP_NONE, /* optinfo_flags */ |
| TV_TREE_SWITCH_LOWERING, /* tv_id */ |
| ( PROP_cfg | PROP_ssa ), /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| TODO_update_ssa | TODO_cleanup_cfg, /* todo_flags_finish */ |
| }; |
| |
| class pass_lower_switch : public gimple_opt_pass |
| { |
| public: |
| pass_lower_switch (gcc::context *ctxt) |
| : gimple_opt_pass (pass_data_lower_switch, ctxt) |
| {} |
| |
| /* opt_pass methods: */ |
| virtual bool gate (function *) { return true; } |
| virtual unsigned int execute (function *); |
| |
| }; // class pass_lower_switch |
| |
| unsigned int |
| pass_lower_switch::execute (function *fun) |
| { |
| basic_block bb; |
| bool expanded = false; |
| |
| 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)); |
| |
| 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)); |
| } |
| } |
| |
| if (expanded) |
| { |
| free_dominance_info (CDI_DOMINATORS); |
| free_dominance_info (CDI_POST_DOMINATORS); |
| mark_virtual_operands_for_renaming (cfun); |
| } |
| |
| return 0; |
| } |
| |
| } // anon namespace |
| |
| gimple_opt_pass * |
| make_pass_lower_switch (gcc::context *ctxt) |
| { |
| return new pass_lower_switch (ctxt); |
| } |
| |
| /* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. |
| PROB is the probability of jumping to LABEL. */ |
| static basic_block |
| do_jump_if_equal (basic_block bb, tree op0, tree op1, basic_block label_bb, |
| profile_probability prob, hash_map<tree, tree> *phi_mapping) |
| { |
| gcond *cond = gimple_build_cond (EQ_EXPR, op0, op1, NULL_TREE, NULL_TREE); |
| gimple_stmt_iterator gsi = gsi_last_bb (bb); |
| gsi_insert_before (&gsi, cond, GSI_SAME_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; |
| } |
| |
| /* 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. |
| |
| Care is taken to prune redundant tests from the decision tree |
| by detecting any boundary conditions already checked by |
| emitted rtx. (See node_has_high_bound, node_has_low_bound |
| and node_is_bounded, above.) |
| |
| Where the test conditions can be shown to be redundant we emit |
| an unconditional jump to the target code. As a further |
| optimization, the subordinates of a tree node are examined to |
| check for bounded nodes. In this case conditional and/or |
| unconditional jumps as a result of the boundary check for the |
| current node are arranged to target the subordinates associated |
| code for out of bound conditions on the current node. |
| |
| We can assume that when control reaches the code generated here, |
| the index value has already been compared with the parents |
| of this node, and determined to be on the same side of each parent |
| as this node is. Thus, if this node tests for the value 51, |
| and a parent tested for 52, we don't need to consider |
| the possibility of a value greater than 51. If another parent |
| tests for the value 50, then this node need not test anything. */ |
| |
| 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 INDEX has an unsigned type, we must make unsigned branches. */ |
| profile_probability probability; |
| profile_probability prob = node->prob, subtree_prob = node->subtree_prob; |
| |
| /* See if our parents have already tested everything for us. |
| If they have, emit an unconditional jump for this node. */ |
| if (node_is_bounded (node, index_type)) |
| { |
| emit_jump (bb, node->case_bb, phi_mapping); |
| return NULL; |
| } |
| |
| else if (tree_int_cst_equal (node->low, node->high)) |
| { |
| probability = conditional_probability (prob, subtree_prob + default_prob); |
| /* Node is single valued. First see if the index expression matches |
| this node and then check our children, if any. */ |
| bb = do_jump_if_equal (bb, index, node->low, node->case_bb, probability, |
| phi_mapping); |
| /* Since this case is taken at this point, reduce its weight from |
| subtree_weight. */ |
| subtree_prob -= prob; |
| if (node->right != 0 && node->left != 0) |
| { |
| /* This node has children on both sides. |
| Dispatch to one side or the other |
| by comparing the index value with this node's value. |
| If one subtree is bounded, check that one first, |
| so we can avoid real branches in the tree. */ |
| |
| if (node_is_bounded (node->right, index_type)) |
| { |
| probability |
| = conditional_probability (node->right->prob, |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR, |
| node->right->case_bb, probability, |
| phi_mapping); |
| bb = emit_case_nodes (bb, index, node->left, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| } |
| |
| else if (node_is_bounded (node->left, index_type)) |
| { |
| probability |
| = conditional_probability (node->left->prob, |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, LT_EXPR, |
| node->left->case_bb, probability, |
| phi_mapping); |
| bb = emit_case_nodes (bb, index, node->right, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| } |
| |
| /* If both children are single-valued cases with no |
| children, finish up all the work. This way, we can save |
| one ordered comparison. */ |
| else if (tree_int_cst_equal (node->right->low, node->right->high) |
| && node->right->left == 0 && node->right->right == 0 |
| && tree_int_cst_equal (node->left->low, node->left->high) |
| && node->left->left == 0 && node->left->right == 0) |
| { |
| /* Neither node is bounded. First distinguish the two sides; |
| then emit the code for one side at a time. */ |
| |
| /* See if the value matches what the right hand side |
| wants. */ |
| probability |
| = conditional_probability (node->right->prob, |
| subtree_prob + default_prob); |
| bb = do_jump_if_equal (bb, index, node->right->low, |
| node->right->case_bb, probability, |
| phi_mapping); |
| |
| /* See if the value matches what the left hand side |
| wants. */ |
| probability |
| = conditional_probability (node->left->prob, |
| subtree_prob + default_prob); |
| bb = do_jump_if_equal (bb, index, node->left->low, |
| node->left->case_bb, probability, |
| phi_mapping); |
| } |
| |
| else |
| { |
| /* Neither node is bounded. First distinguish the two sides; |
| then emit the code for one side at a time. */ |
| |
| basic_block test_bb = split_edge (single_succ_edge (bb)); |
| redirect_edge_succ (single_pred_edge (test_bb), |
| single_succ_edge (bb)->dest); |
| |
| /* The default label could be reached either through the right |
| subtree or the left subtree. Divide the probability |
| equally. */ |
| probability |
| = conditional_probability (node->right->subtree_prob |
| + default_prob.apply_scale (1, 2), |
| subtree_prob + default_prob); |
| /* See if the value is on the right. */ |
| 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 must be on the left. |
| Handle the left-hand subtree. */ |
| bb = emit_case_nodes (bb, index, node->left, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| /* If left-hand subtree does nothing, |
| go to default. */ |
| |
| if (bb && default_bb) |
| emit_jump (bb, default_bb, phi_mapping); |
| |
| /* Code branches here for the right-hand subtree. */ |
| bb = emit_case_nodes (test_bb, index, node->right, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| } |
| } |
| else if (node->right != 0 && node->left == 0) |
| { |
| /* Here we have a right child but no left so we issue a conditional |
| branch to default and process the right child. |
| |
| Omit the conditional branch to default if the right child |
| does not have any children and is single valued; it would |
| cost too much space to save so little time. */ |
| |
| if (node->right->right || node->right->left |
| || !tree_int_cst_equal (node->right->low, node->right->high)) |
| { |
| if (!node_has_low_bound (node, index_type)) |
| { |
| probability |
| = conditional_probability (default_prob.apply_scale (1, 2), |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, LT_EXPR, |
| default_bb, probability, |
| phi_mapping); |
| default_prob = default_prob.apply_scale (1, 2); |
| } |
| |
| bb = emit_case_nodes (bb, index, node->right, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| } |
| else |
| { |
| probability |
| = conditional_probability (node->right->subtree_prob, |
| subtree_prob + default_prob); |
| /* We cannot process node->right normally |
| since we haven't ruled out the numbers less than |
| this node's value. So handle node->right explicitly. */ |
| bb = do_jump_if_equal (bb, index, node->right->low, |
| node->right->case_bb, probability, |
| phi_mapping); |
| } |
| } |
| |
| else if (node->right == 0 && node->left != 0) |
| { |
| /* Just one subtree, on the left. */ |
| if (node->left->left || node->left->right |
| || !tree_int_cst_equal (node->left->low, node->left->high)) |
| { |
| if (!node_has_high_bound (node, index_type)) |
| { |
| probability |
| = conditional_probability (default_prob.apply_scale (1, 2), |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR, |
| default_bb, probability, |
| phi_mapping); |
| default_prob = default_prob.apply_scale (1, 2); |
| } |
| |
| bb = emit_case_nodes (bb, index, node->left, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| } |
| else |
| { |
| probability |
| = conditional_probability (node->left->subtree_prob, |
| subtree_prob + default_prob); |
| /* We cannot process node->left normally |
| since we haven't ruled out the numbers less than |
| this node's value. So handle node->left explicitly. */ |
| do_jump_if_equal (bb, index, node->left->low, node->left->case_bb, |
| probability, phi_mapping); |
| } |
| } |
| } |
| else |
| { |
| /* Node is a range. These cases are very similar to those for a single |
| value, except that we do not start by testing whether this node |
| is the one to branch to. */ |
| |
| if (node->right != 0 && node->left != 0) |
| { |
| /* Node has subtrees on both sides. |
| If the right-hand subtree is bounded, |
| test for it first, since we can go straight there. |
| Otherwise, we need to make a branch in the control structure, |
| then handle the two subtrees. */ |
| basic_block test_bb = NULL; |
| |
| if (node_is_bounded (node->right, index_type)) |
| { |
| /* Right hand node is fully bounded so we can eliminate any |
| testing and branch directly to the target code. */ |
| probability |
| = conditional_probability (node->right->subtree_prob, |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR, |
| node->right->case_bb, probability, |
| phi_mapping); |
| } |
| else |
| { |
| /* Right hand node requires testing. |
| Branch to a label where we will handle it later. */ |
| |
| test_bb = split_edge (single_succ_edge (bb)); |
| redirect_edge_succ (single_pred_edge (test_bb), |
| single_succ_edge (bb)->dest); |
| |
| probability |
| = conditional_probability (node->right->subtree_prob |
| + default_prob.apply_scale (1, 2), |
| 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 (prob, 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 right node had to be handled later, do that now. */ |
| if (test_bb) |
| { |
| /* If the left-hand subtree fell through, |
| don't let it fall into the right-hand subtree. */ |
| if (bb && 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); |
| } |
| } |
| |
| else if (node->right != 0 && node->left == 0) |
| { |
| /* Deal with values to the left of this node, |
| if they are possible. */ |
| if (!node_has_low_bound (node, index_type)) |
| { |
| probability |
| = conditional_probability (default_prob.apply_scale (1, 2), |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->low, LT_EXPR, |
| default_bb, probability, |
| phi_mapping); |
| default_prob = default_prob.apply_scale (1, 2); |
| } |
| |
| /* Value belongs to this node or to the right-hand subtree. */ |
| |
| probability |
| = conditional_probability (prob, subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, LE_EXPR, |
| node->case_bb, probability, |
| phi_mapping); |
| |
| bb = emit_case_nodes (bb, index, node->right, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| } |
| |
| else if (node->right == 0 && node->left != 0) |
| { |
| /* Deal with values to the right of this node, |
| if they are possible. */ |
| if (!node_has_high_bound (node, index_type)) |
| { |
| probability |
| = conditional_probability (default_prob.apply_scale (1, 2), |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR, |
| default_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 (prob, subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->low, GE_EXPR, |
| node->case_bb, probability, |
| phi_mapping); |
| |
| bb = emit_case_nodes (bb, index, node->left, default_bb, |
| default_label, default_prob, index_type, |
| phi_mapping); |
| } |
| |
| else |
| { |
| /* Node has no children so we check low and high bounds to remove |
| redundant tests. Only one of the bounds can exist, |
| since otherwise this node is bounded--a case tested already. */ |
| bool high_bound = node_has_high_bound (node, index_type); |
| bool low_bound = node_has_low_bound (node, index_type); |
| |
| if (!high_bound && low_bound) |
| { |
| probability |
| = conditional_probability (default_prob, |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->high, GT_EXPR, |
| default_bb, probability, |
| phi_mapping); |
| } |
| |
| else if (!low_bound && high_bound) |
| { |
| probability |
| = conditional_probability (default_prob, |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->low, LT_EXPR, |
| default_bb, probability, |
| phi_mapping); |
| } |
| else if (!low_bound && !high_bound) |
| { |
| tree lhs, rhs; |
| generate_range_test (bb, index, node->low, node->high, |
| &lhs, &rhs); |
| probability |
| = conditional_probability (default_prob, |
| subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, lhs, rhs, GT_EXPR, |
| default_bb, probability, |
| phi_mapping); |
| } |
| |
| emit_jump (bb, node->case_bb, phi_mapping); |
| return NULL; |
| } |
| } |
| |
| return bb; |
| } |
| |
| /* Search the parent sections of the case node tree |
| to see if a test for the lower bound of NODE would be redundant. |
| INDEX_TYPE is the type of the index expression. |
| |
| The instructions to generate the case decision tree are |
| output in the same order as nodes are processed so it is |
| known that if a parent node checks the range of the current |
| node minus one that the current node is bounded at its lower |
| span. Thus the test would be redundant. */ |
| |
| static bool |
| node_has_low_bound (case_node_ptr node, tree index_type) |
| { |
| tree low_minus_one; |
| case_node_ptr pnode; |
| |
| /* If the lower bound of this node is the lowest value in the index type, |
| we need not test it. */ |
| |
| if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type))) |
| return true; |
| |
| /* If this node has a left branch, the value at the left must be less |
| than that at this node, so it cannot be bounded at the bottom and |
| we need not bother testing any further. */ |
| |
| if (node->left) |
| return false; |
| |
| low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low), node->low, |
| build_int_cst (TREE_TYPE (node->low), 1)); |
| |
| /* If the subtraction above overflowed, we can't verify anything. |
| Otherwise, look for a parent that tests our value - 1. */ |
| |
| if (!tree_int_cst_lt (low_minus_one, node->low)) |
| return false; |
| |
| for (pnode = node->parent; pnode; pnode = pnode->parent) |
| if (tree_int_cst_equal (low_minus_one, pnode->high)) |
| return true; |
| |
| return false; |
| } |
| |
| /* Search the parent sections of the case node tree |
| to see if a test for the upper bound of NODE would be redundant. |
| INDEX_TYPE is the type of the index expression. |
| |
| The instructions to generate the case decision tree are |
| output in the same order as nodes are processed so it is |
| known that if a parent node checks the range of the current |
| node plus one that the current node is bounded at its upper |
| span. Thus the test would be redundant. */ |
| |
| static bool |
| node_has_high_bound (case_node_ptr node, tree index_type) |
| { |
| tree high_plus_one; |
| case_node_ptr pnode; |
| |
| /* If there is no upper bound, obviously no test is needed. */ |
| |
| if (TYPE_MAX_VALUE (index_type) == NULL) |
| return true; |
| |
| /* If the upper bound of this node is the highest value in the type |
| of the index expression, we need not test against it. */ |
| |
| if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type))) |
| return true; |
| |
| /* If this node has a right branch, the value at the right must be greater |
| than that at this node, so it cannot be bounded at the top and |
| we need not bother testing any further. */ |
| |
| if (node->right) |
| return false; |
| |
| high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high), node->high, |
| build_int_cst (TREE_TYPE (node->high), 1)); |
| |
| /* If the addition above overflowed, we can't verify anything. |
| Otherwise, look for a parent that tests our value + 1. */ |
| |
| if (!tree_int_cst_lt (node->high, high_plus_one)) |
| return false; |
| |
| for (pnode = node->parent; pnode; pnode = pnode->parent) |
| if (tree_int_cst_equal (high_plus_one, pnode->low)) |
| return true; |
| |
| return false; |
| } |
| |
| /* Search the parent sections of the |
| case node tree to see if both tests for the upper and lower |
| bounds of NODE would be redundant. */ |
| |
| static bool |
| node_is_bounded (case_node_ptr node, tree index_type) |
| { |
| return (node_has_low_bound (node, index_type) |
| && node_has_high_bound (node, index_type)); |
| } |