| /* Lower GIMPLE_SWITCH expressions to something more efficient than |
| a jump table. |
| Copyright (C) 2006-2021 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 "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 "gimple-fold.h" |
| #include "tree-cfg.h" |
| #include "cfgloop.h" |
| #include "alloc-pool.h" |
| #include "target.h" |
| #include "tree-into-ssa.h" |
| #include "omp-general.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" |
| |
| #include "tree-switch-conversion.h" |
| |
| using namespace tree_switch_conversion; |
| |
| /* Constructor. */ |
| |
| switch_conversion::switch_conversion (): m_final_bb (NULL), |
| m_constructors (NULL), m_default_values (NULL), |
| m_arr_ref_first (NULL), m_arr_ref_last (NULL), |
| m_reason (NULL), m_default_case_nonstandard (false), m_cfg_altered (false) |
| { |
| } |
| |
| /* Collection information about SWTCH statement. */ |
| |
| void |
| switch_conversion::collect (gswitch *swtch) |
| { |
| unsigned int branch_num = gimple_switch_num_labels (swtch); |
| tree min_case, max_case; |
| unsigned int i; |
| edge e, e_default, e_first; |
| edge_iterator ei; |
| |
| m_switch = swtch; |
| |
| /* 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. */ |
| m_index_expr = gimple_switch_index (swtch); |
| m_switch_bb = gimple_bb (swtch); |
| e_default = gimple_switch_default_edge (cfun, swtch); |
| m_default_bb = e_default->dest; |
| m_default_prob = e_default->probability; |
| |
| /* 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); |
| |
| m_range_min = CASE_LOW (min_case); |
| if (CASE_HIGH (max_case) != NULL_TREE) |
| m_range_max = CASE_HIGH (max_case); |
| else |
| m_range_max = CASE_LOW (max_case); |
| |
| m_contiguous_range = true; |
| tree last = CASE_HIGH (min_case) ? CASE_HIGH (min_case) : m_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))) |
| { |
| m_contiguous_range = false; |
| break; |
| } |
| last = CASE_HIGH (elt) ? CASE_HIGH (elt) : CASE_LOW (elt); |
| } |
| |
| if (m_contiguous_range) |
| e_first = gimple_switch_edge (cfun, swtch, 1); |
| else |
| 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)) |
| m_final_bb = e_first->dest; |
| else if (single_succ_p (e_first->dest) |
| && ! single_pred_p (single_succ (e_first->dest))) |
| m_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 (m_final_bb) |
| FOR_EACH_EDGE (e, ei, m_switch_bb->succs) |
| { |
| if (e->dest == m_final_bb) |
| continue; |
| |
| if (single_pred_p (e->dest) |
| && single_succ_p (e->dest) |
| && single_succ (e->dest) == m_final_bb) |
| continue; |
| |
| if (e == e_default && m_contiguous_range) |
| { |
| m_default_case_nonstandard = true; |
| continue; |
| } |
| |
| m_final_bb = NULL; |
| break; |
| } |
| |
| m_range_size |
| = int_const_binop (MINUS_EXPR, m_range_max, m_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. */ |
| m_count = 0; |
| for (i = 1; i < branch_num; i++) |
| { |
| tree elt = gimple_switch_label (swtch, i); |
| m_count++; |
| if (CASE_HIGH (elt) |
| && ! tree_int_cst_equal (CASE_LOW (elt), CASE_HIGH (elt))) |
| m_count++; |
| } |
| |
| /* Get the number of unique non-default targets out of the GIMPLE_SWITCH |
| block. Assume a CFG cleanup would have already removed degenerate |
| switch statements, this allows us to just use EDGE_COUNT. */ |
| m_uniq = EDGE_COUNT (gimple_bb (swtch)->succs) - 1; |
| } |
| |
| /* Checks whether the range given by individual case statements of the switch |
| switch statement isn't too big and whether the number of branches actually |
| satisfies the size of the new array. */ |
| |
| bool |
| switch_conversion::check_range () |
| { |
| gcc_assert (m_range_size); |
| if (!tree_fits_uhwi_p (m_range_size)) |
| { |
| m_reason = "index range way too large or otherwise unusable"; |
| return false; |
| } |
| |
| if (tree_to_uhwi (m_range_size) |
| > ((unsigned) m_count * param_switch_conversion_branch_ratio)) |
| { |
| m_reason = "the maximum range-branch ratio exceeded"; |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /* Checks whether all but the final BB basic blocks are empty. */ |
| |
| bool |
| switch_conversion::check_all_empty_except_final () |
| { |
| edge e, e_default = find_edge (m_switch_bb, m_default_bb); |
| edge_iterator ei; |
| |
| FOR_EACH_EDGE (e, ei, m_switch_bb->succs) |
| { |
| if (e->dest == m_final_bb) |
| continue; |
| |
| if (!empty_block_p (e->dest)) |
| { |
| if (m_contiguous_range && e == e_default) |
| { |
| m_default_case_nonstandard = true; |
| continue; |
| } |
| |
| m_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. */ |
| |
| bool |
| switch_conversion::check_final_bb () |
| { |
| gphi_iterator gsi; |
| |
| m_phi_count = 0; |
| for (gsi = gsi_start_phis (m_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; |
| |
| m_phi_count++; |
| |
| for (i = 0; i < gimple_phi_num_args (phi); i++) |
| { |
| basic_block bb = gimple_phi_arg_edge (phi, i)->src; |
| |
| if (bb == m_switch_bb |
| || (single_pred_p (bb) |
| && single_pred (bb) == m_switch_bb |
| && (!m_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 == m_switch_bb) |
| bb = m_final_bb; |
| if (!m_contiguous_range || bb != m_default_bb) |
| { |
| m_reason = reason; |
| return false; |
| } |
| |
| unsigned int branch_num = gimple_switch_num_labels (m_switch); |
| for (unsigned int i = 1; i < branch_num; i++) |
| { |
| if (gimple_switch_label_bb (cfun, m_switch, i) == bb) |
| { |
| m_reason = reason; |
| return false; |
| } |
| } |
| m_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. */ |
| |
| void |
| switch_conversion::create_temp_arrays () |
| { |
| int i; |
| |
| m_default_values = XCNEWVEC (tree, m_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; |
| m_constructors = XCNEWVEC (vec_constructor_elt_gc, m_phi_count); |
| m_target_inbound_names = m_default_values + m_phi_count; |
| m_target_outbound_names = m_target_inbound_names + m_phi_count; |
| for (i = 0; i < m_phi_count; i++) |
| vec_alloc (m_constructors[i], tree_to_uhwi (m_range_size) + 1); |
| } |
| |
| /* 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. */ |
| |
| void |
| switch_conversion::gather_default_values (tree default_case) |
| { |
| gphi_iterator gsi; |
| basic_block bb = label_to_block (cfun, CASE_LABEL (default_case)); |
| edge e; |
| int i = 0; |
| |
| gcc_assert (CASE_LOW (default_case) == NULL_TREE |
| || m_default_case_nonstandard); |
| |
| if (bb == m_final_bb) |
| e = find_edge (m_switch_bb, bb); |
| else |
| e = single_succ_edge (bb); |
| |
| for (gsi = gsi_start_phis (m_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); |
| m_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. */ |
| |
| void |
| switch_conversion::build_constructors () |
| { |
| unsigned i, branch_num = gimple_switch_num_labels (m_switch); |
| tree pos = m_range_min; |
| tree pos_one = build_int_cst (TREE_TYPE (pos), 1); |
| |
| for (i = 1; i < branch_num; i++) |
| { |
| tree cs = gimple_switch_label (m_switch, i); |
| basic_block bb = label_to_block (cfun, CASE_LABEL (cs)); |
| edge e; |
| tree high; |
| gphi_iterator gsi; |
| int j; |
| |
| if (bb == m_final_bb) |
| e = find_edge (m_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 < m_phi_count; k++) |
| { |
| constructor_elt elt; |
| |
| elt.index = int_const_binop (MINUS_EXPR, pos, m_range_min); |
| elt.value |
| = unshare_expr_without_location (m_default_values[k]); |
| m_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 (m_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, m_range_min); |
| elt.value = unshare_expr_without_location (val); |
| m_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 products of a linear function |
| a * x + b, then return true. When true, COEFF_A and COEFF_B and |
| coefficients of the linear function. Note that equal values are special |
| case of a linear function with a and b equal to zero. */ |
| |
| bool |
| switch_conversion::contains_linear_function_p (vec<constructor_elt, va_gc> *vec, |
| wide_int *coeff_a, |
| wide_int *coeff_b) |
| { |
| unsigned int i; |
| constructor_elt *elt; |
| |
| gcc_assert (vec->length () >= 2); |
| |
| /* Let's try to find any linear function a * x + y that can apply to |
| given values. 'a' can be calculated as follows: |
| |
| a = (y2 - y1) / (x2 - x1) where x2 - x1 = 1 (consecutive case indices) |
| a = y2 - y1 |
| |
| and |
| |
| b = y2 - a * x2 |
| |
| */ |
| |
| tree elt0 = (*vec)[0].value; |
| tree elt1 = (*vec)[1].value; |
| |
| if (TREE_CODE (elt0) != INTEGER_CST || TREE_CODE (elt1) != INTEGER_CST) |
| return false; |
| |
| wide_int range_min |
| = wide_int::from (wi::to_wide (m_range_min), |
| TYPE_PRECISION (TREE_TYPE (elt0)), |
| TYPE_SIGN (TREE_TYPE (m_range_min))); |
| wide_int y1 = wi::to_wide (elt0); |
| wide_int y2 = wi::to_wide (elt1); |
| wide_int a = y2 - y1; |
| wide_int b = y2 - a * (range_min + 1); |
| |
| /* Verify that all values fulfill the linear function. */ |
| FOR_EACH_VEC_SAFE_ELT (vec, i, elt) |
| { |
| if (TREE_CODE (elt->value) != INTEGER_CST) |
| return false; |
| |
| wide_int value = wi::to_wide (elt->value); |
| if (a * range_min + b != value) |
| return false; |
| |
| ++range_min; |
| } |
| |
| *coeff_a = a; |
| *coeff_b = b; |
| |
| return true; |
| } |
| |
| /* 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. */ |
| |
| tree |
| switch_conversion::array_value_type (tree type, int num) |
| { |
| unsigned int i, len = vec_safe_length (m_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 (m_switch)) ? 2 : 32)) |
| return type; |
| |
| FOR_EACH_VEC_SAFE_ELT (m_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. */ |
| |
| void |
| switch_conversion::build_one_array (int num, tree arr_index_type, |
| gphi *phi, tree tidx) |
| { |
| tree name; |
| gimple *load; |
| gimple_stmt_iterator gsi = gsi_for_stmt (m_switch); |
| location_t loc = gimple_location (m_switch); |
| |
| gcc_assert (m_default_values[num]); |
| |
| name = copy_ssa_name (PHI_RESULT (phi)); |
| m_target_inbound_names[num] = name; |
| |
| vec<constructor_elt, va_gc> *constructor = m_constructors[num]; |
| wide_int coeff_a, coeff_b; |
| bool linear_p = contains_linear_function_p (constructor, &coeff_a, &coeff_b); |
| tree type; |
| if (linear_p |
| && (type = range_check_type (TREE_TYPE ((*constructor)[0].value)))) |
| { |
| if (dump_file && coeff_a.to_uhwi () > 0) |
| fprintf (dump_file, "Linear transformation with A = %" PRId64 |
| " and B = %" PRId64 "\n", coeff_a.to_shwi (), |
| coeff_b.to_shwi ()); |
| |
| /* We must use type of constructor values. */ |
| gimple_seq seq = NULL; |
| tree tmp = gimple_convert (&seq, type, m_index_expr); |
| tree tmp2 = gimple_build (&seq, MULT_EXPR, type, |
| wide_int_to_tree (type, coeff_a), tmp); |
| tree tmp3 = gimple_build (&seq, PLUS_EXPR, type, tmp2, |
| wide_int_to_tree (type, coeff_b)); |
| tree tmp4 = gimple_convert (&seq, TREE_TYPE (name), tmp3); |
| gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT); |
| load = gimple_build_assign (name, tmp4); |
| } |
| else |
| { |
| tree array_type, ctor, decl, value_type, fetch, default_type; |
| |
| default_type = TREE_TYPE (m_default_values[num]); |
| value_type = array_value_type (default_type, num); |
| 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 (constructor, i, elt) |
| elt->value = fold_convert (value_type, elt->value); |
| } |
| ctor = build_constructor (array_type, constructor); |
| 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; |
| if (offloading_function_p (cfun->decl)) |
| DECL_ATTRIBUTES (decl) |
| = tree_cons (get_identifier ("omp declare target"), NULL_TREE, |
| NULL_TREE); |
| 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); |
| m_arr_ref_last = load; |
| } |
| |
| /* Builds and initializes static arrays initialized with values gathered from |
| the switch statement. Also creates statements that load values from |
| them. */ |
| |
| void |
| switch_conversion::build_arrays () |
| { |
| tree arr_index_type; |
| tree tidx, sub, utype; |
| gimple *stmt; |
| gimple_stmt_iterator gsi; |
| gphi_iterator gpi; |
| int i; |
| location_t loc = gimple_location (m_switch); |
| |
| gsi = gsi_for_stmt (m_switch); |
| |
| /* Make sure we do not generate arithmetics in a subrange. */ |
| utype = TREE_TYPE (m_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 (m_range_size); |
| tidx = make_ssa_name (utype); |
| sub = fold_build2_loc (loc, MINUS_EXPR, utype, |
| fold_convert_loc (loc, utype, m_index_expr), |
| fold_convert_loc (loc, utype, m_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); |
| m_arr_ref_first = stmt; |
| |
| for (gpi = gsi_start_phis (m_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 (i++, arr_index_type, phi, tidx); |
| else |
| { |
| edge e; |
| edge_iterator ei; |
| FOR_EACH_EDGE (e, ei, m_switch_bb->succs) |
| { |
| if (e->dest == m_final_bb) |
| break; |
| if (!m_default_case_nonstandard |
| || e->dest != m_default_bb) |
| { |
| e = single_succ_edge (e->dest); |
| break; |
| } |
| } |
| gcc_assert (e && e->dest == m_final_bb); |
| m_target_vop = PHI_ARG_DEF_FROM_EDGE (phi, e); |
| } |
| } |
| } |
| |
| /* Generates and appropriately inserts loads of default values at the position |
| given by GSI. Returns the last inserted statement. */ |
| |
| gassign * |
| switch_conversion::gen_def_assigns (gimple_stmt_iterator *gsi) |
| { |
| int i; |
| gassign *assign = NULL; |
| |
| for (i = 0; i < m_phi_count; i++) |
| { |
| tree name = copy_ssa_name (m_target_inbound_names[i]); |
| m_target_outbound_names[i] = name; |
| assign = gimple_build_assign (name, m_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). */ |
| |
| void |
| switch_conversion::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). */ |
| |
| void |
| switch_conversion::fix_phi_nodes (edge e1f, edge e2f, basic_block bbf) |
| { |
| 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 = m_target_vop; |
| else |
| { |
| inbound = m_target_inbound_names[i]; |
| outbound = m_target_outbound_names[i++]; |
| } |
| add_phi_arg (phi, inbound, e1f, UNKNOWN_LOCATION); |
| if (!m_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. */ |
| |
| void |
| switch_conversion::gen_inbound_check () |
| { |
| 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 (m_switch); |
| |
| gcc_assert (m_default_values); |
| |
| bb0 = gimple_bb (m_switch); |
| |
| tidx = gimple_assign_lhs (m_arr_ref_first); |
| utype = TREE_TYPE (tidx); |
| |
| /* (end of) block 0 */ |
| gsi = gsi_for_stmt (m_arr_ref_first); |
| gsi_next (&gsi); |
| |
| bound = fold_convert_loc (loc, utype, m_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 (!m_default_case_nonstandard) |
| { |
| label2 = gimple_build_label (label_decl2); |
| gsi_insert_before (&gsi, label2, GSI_SAME_STMT); |
| last_assign = gen_def_assigns (&gsi); |
| } |
| |
| /* block 1 */ |
| label1 = gimple_build_label (label_decl1); |
| gsi_insert_before (&gsi, label1, GSI_SAME_STMT); |
| |
| /* block F */ |
| gsi = gsi_start_bb (m_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 (m_default_case_nonstandard) |
| { |
| bb1 = bb2; |
| bb2 = m_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, m_arr_ref_last); |
| bbd = e1d->dest; |
| remove_edge (e1d); |
| |
| /* Flags and profiles of the edge for in-range values. */ |
| if (!m_default_case_nonstandard) |
| e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE); |
| e01->probability = m_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 = m_default_prob; |
| |
| bbf = m_final_bb; |
| |
| e1f = make_edge (bb1, bbf, EDGE_FALLTHRU); |
| e1f->probability = profile_probability::always (); |
| |
| if (m_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 (!m_default_case_nonstandard) |
| bbf->count = e1f->count () + e2f->count (); |
| |
| /* Tidy blocks that have become unreachable. */ |
| prune_bbs (bbd, m_final_bb, |
| m_default_case_nonstandard ? m_default_bb : NULL); |
| |
| /* Fixup the PHI nodes in bbF. */ |
| fix_phi_nodes (e1f, e2f, bbf); |
| |
| /* 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 (!m_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. On success, NULL is in m_reason, otherwise points |
| to a string with the reason why the conversion failed. */ |
| |
| void |
| switch_conversion::expand (gswitch *swtch) |
| { |
| /* Group case labels so that we get the right results from the heuristics |
| that decide on the code generation approach for this switch. */ |
| m_cfg_altered |= 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) |
| { |
| m_reason = "switch is a degenerate case"; |
| return; |
| } |
| |
| collect (swtch); |
| |
| /* No error markers should reach here (they should be filtered out |
| during gimplification). */ |
| gcc_checking_assert (TREE_TYPE (m_index_expr) != error_mark_node); |
| |
| /* Prefer bit test if possible. */ |
| if (tree_fits_uhwi_p (m_range_size) |
| && bit_test_cluster::can_be_handled (tree_to_uhwi (m_range_size), m_uniq) |
| && bit_test_cluster::is_beneficial (m_count, m_uniq)) |
| { |
| m_reason = "expanding as bit test is preferable"; |
| return; |
| } |
| |
| if (m_uniq <= 2) |
| { |
| /* This will be expanded as a decision tree . */ |
| m_reason = "expanding as jumps is preferable"; |
| return; |
| } |
| |
| /* If there is no common successor, we cannot do the transformation. */ |
| if (!m_final_bb) |
| { |
| m_reason = "no common successor to all case label target blocks found"; |
| return; |
| } |
| |
| /* Check the case label values are within reasonable range: */ |
| if (!check_range ()) |
| { |
| gcc_assert (m_reason); |
| return; |
| } |
| |
| /* For all the cases, see whether they are empty, the assignments they |
| represent constant and so on... */ |
| if (!check_all_empty_except_final ()) |
| { |
| gcc_assert (m_reason); |
| return; |
| } |
| if (!check_final_bb ()) |
| { |
| gcc_assert (m_reason); |
| return; |
| } |
| |
| /* At this point all checks have passed and we can proceed with the |
| transformation. */ |
| |
| create_temp_arrays (); |
| gather_default_values (m_default_case_nonstandard |
| ? gimple_switch_label (swtch, 1) |
| : gimple_switch_default_label (swtch)); |
| build_constructors (); |
| |
| build_arrays (); /* Build the static arrays and assignments. */ |
| gen_inbound_check (); /* Build the bounds check. */ |
| |
| m_cfg_altered = true; |
| } |
| |
| /* Destructor. */ |
| |
| switch_conversion::~switch_conversion () |
| { |
| XDELETEVEC (m_constructors); |
| XDELETEVEC (m_default_values); |
| } |
| |
| /* Constructor. */ |
| |
| group_cluster::group_cluster (vec<cluster *> &clusters, |
| unsigned start, unsigned end) |
| { |
| gcc_checking_assert (end - start + 1 >= 1); |
| m_prob = profile_probability::never (); |
| m_cases.create (end - start + 1); |
| for (unsigned i = start; i <= end; i++) |
| { |
| m_cases.quick_push (static_cast<simple_cluster *> (clusters[i])); |
| m_prob += clusters[i]->m_prob; |
| } |
| m_subtree_prob = m_prob; |
| } |
| |
| /* Destructor. */ |
| |
| group_cluster::~group_cluster () |
| { |
| for (unsigned i = 0; i < m_cases.length (); i++) |
| delete m_cases[i]; |
| |
| m_cases.release (); |
| } |
| |
| /* Dump content of a cluster. */ |
| |
| void |
| group_cluster::dump (FILE *f, bool details) |
| { |
| unsigned total_values = 0; |
| for (unsigned i = 0; i < m_cases.length (); i++) |
| total_values += m_cases[i]->get_range (m_cases[i]->get_low (), |
| m_cases[i]->get_high ()); |
| |
| unsigned comparison_count = 0; |
| for (unsigned i = 0; i < m_cases.length (); i++) |
| { |
| simple_cluster *sc = static_cast<simple_cluster *> (m_cases[i]); |
| comparison_count += sc->m_range_p ? 2 : 1; |
| } |
| |
| unsigned HOST_WIDE_INT range = get_range (get_low (), get_high ()); |
| fprintf (f, "%s", get_type () == JUMP_TABLE ? "JT" : "BT"); |
| |
| if (details) |
| fprintf (f, "(values:%d comparisons:%d range:" HOST_WIDE_INT_PRINT_DEC |
| " density: %.2f%%)", total_values, comparison_count, range, |
| 100.0f * comparison_count / range); |
| |
| fprintf (f, ":"); |
| PRINT_CASE (f, get_low ()); |
| fprintf (f, "-"); |
| PRINT_CASE (f, get_high ()); |
| fprintf (f, " "); |
| } |
| |
| /* Emit GIMPLE code to handle the cluster. */ |
| |
| void |
| jump_table_cluster::emit (tree index_expr, tree, |
| tree default_label_expr, basic_block default_bb, |
| location_t loc) |
| { |
| unsigned HOST_WIDE_INT range = get_range (get_low (), get_high ()); |
| unsigned HOST_WIDE_INT nondefault_range = 0; |
| |
| /* For jump table we just emit a new gswitch statement that will |
| be latter lowered to jump table. */ |
| auto_vec <tree> labels; |
| labels.create (m_cases.length ()); |
| |
| make_edge (m_case_bb, default_bb, 0); |
| for (unsigned i = 0; i < m_cases.length (); i++) |
| { |
| labels.quick_push (unshare_expr (m_cases[i]->m_case_label_expr)); |
| make_edge (m_case_bb, m_cases[i]->m_case_bb, 0); |
| } |
| |
| gswitch *s = gimple_build_switch (index_expr, |
| unshare_expr (default_label_expr), labels); |
| gimple_set_location (s, loc); |
| gimple_stmt_iterator gsi = gsi_start_bb (m_case_bb); |
| gsi_insert_after (&gsi, s, GSI_NEW_STMT); |
| |
| /* Set up even probabilities for all cases. */ |
| for (unsigned i = 0; i < m_cases.length (); i++) |
| { |
| simple_cluster *sc = static_cast<simple_cluster *> (m_cases[i]); |
| edge case_edge = find_edge (m_case_bb, sc->m_case_bb); |
| unsigned HOST_WIDE_INT case_range |
| = sc->get_range (sc->get_low (), sc->get_high ()); |
| nondefault_range += case_range; |
| |
| /* case_edge->aux is number of values in a jump-table that are covered |
| by the case_edge. */ |
| case_edge->aux = (void *) ((intptr_t) (case_edge->aux) + case_range); |
| } |
| |
| edge default_edge = gimple_switch_default_edge (cfun, s); |
| default_edge->probability = profile_probability::never (); |
| |
| for (unsigned i = 0; i < m_cases.length (); i++) |
| { |
| simple_cluster *sc = static_cast<simple_cluster *> (m_cases[i]); |
| edge case_edge = find_edge (m_case_bb, sc->m_case_bb); |
| case_edge->probability |
| = profile_probability::always ().apply_scale ((intptr_t)case_edge->aux, |
| range); |
| } |
| |
| /* Number of non-default values is probability of default edge. */ |
| default_edge->probability |
| += profile_probability::always ().apply_scale (nondefault_range, |
| range).invert (); |
| |
| switch_decision_tree::reset_out_edges_aux (s); |
| } |
| |
| /* Find jump tables of given CLUSTERS, where all members of the vector |
| are of type simple_cluster. New clusters are returned. */ |
| |
| vec<cluster *> |
| jump_table_cluster::find_jump_tables (vec<cluster *> &clusters) |
| { |
| if (!is_enabled ()) |
| return clusters.copy (); |
| |
| unsigned l = clusters.length (); |
| auto_vec<min_cluster_item> min; |
| min.reserve (l + 1); |
| |
| min.quick_push (min_cluster_item (0, 0, 0)); |
| |
| for (unsigned i = 1; i <= l; i++) |
| { |
| /* Set minimal # of clusters with i-th item to infinite. */ |
| min.quick_push (min_cluster_item (INT_MAX, INT_MAX, INT_MAX)); |
| |
| for (unsigned j = 0; j < i; j++) |
| { |
| unsigned HOST_WIDE_INT s = min[j].m_non_jt_cases; |
| if (i - j < case_values_threshold ()) |
| s += i - j; |
| |
| /* Prefer clusters with smaller number of numbers covered. */ |
| if ((min[j].m_count + 1 < min[i].m_count |
| || (min[j].m_count + 1 == min[i].m_count |
| && s < min[i].m_non_jt_cases)) |
| && can_be_handled (clusters, j, i - 1)) |
| min[i] = min_cluster_item (min[j].m_count + 1, j, s); |
| } |
| |
| gcc_checking_assert (min[i].m_count != INT_MAX); |
| } |
| |
| /* No result. */ |
| if (min[l].m_count == l) |
| return clusters.copy (); |
| |
| vec<cluster *> output; |
| output.create (4); |
| |
| /* Find and build the clusters. */ |
| for (unsigned int end = l;;) |
| { |
| int start = min[end].m_start; |
| |
| /* Do not allow clusters with small number of cases. */ |
| if (is_beneficial (clusters, start, end - 1)) |
| output.safe_push (new jump_table_cluster (clusters, start, end - 1)); |
| else |
| for (int i = end - 1; i >= start; i--) |
| output.safe_push (clusters[i]); |
| |
| end = start; |
| |
| if (start <= 0) |
| break; |
| } |
| |
| output.reverse (); |
| return output; |
| } |
| |
| /* Return true when cluster starting at START and ending at END (inclusive) |
| can build a jump-table. */ |
| |
| bool |
| jump_table_cluster::can_be_handled (const vec<cluster *> &clusters, |
| unsigned start, unsigned end) |
| { |
| /* If the switch is relatively small such that the cost of one |
| indirect jump on the target are higher than the cost of a |
| decision tree, go with the decision tree. |
| |
| 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. |
| |
| For algorithm correctness, jump table for a single case must return |
| true. We bail out in is_beneficial if it's called just for |
| a single case. */ |
| if (start == end) |
| return true; |
| |
| unsigned HOST_WIDE_INT max_ratio |
| = (optimize_insn_for_size_p () |
| ? param_jump_table_max_growth_ratio_for_size |
| : param_jump_table_max_growth_ratio_for_speed); |
| unsigned HOST_WIDE_INT range = get_range (clusters[start]->get_low (), |
| clusters[end]->get_high ()); |
| /* Check overflow. */ |
| if (range == 0) |
| return false; |
| |
| if (range > HOST_WIDE_INT_M1U / 100) |
| return false; |
| |
| unsigned HOST_WIDE_INT lhs = 100 * range; |
| if (lhs < range) |
| return false; |
| |
| /* First make quick guess as each cluster |
| can add at maximum 2 to the comparison_count. */ |
| if (lhs > 2 * max_ratio * (end - start + 1)) |
| return false; |
| |
| unsigned HOST_WIDE_INT comparison_count = 0; |
| for (unsigned i = start; i <= end; i++) |
| { |
| simple_cluster *sc = static_cast<simple_cluster *> (clusters[i]); |
| comparison_count += sc->m_range_p ? 2 : 1; |
| } |
| |
| return lhs <= max_ratio * comparison_count; |
| } |
| |
| /* Return true if cluster starting at START and ending at END (inclusive) |
| is profitable transformation. */ |
| |
| bool |
| jump_table_cluster::is_beneficial (const vec<cluster *> &, |
| unsigned start, unsigned end) |
| { |
| /* Single case bail out. */ |
| if (start == end) |
| return false; |
| |
| return end - start + 1 >= case_values_threshold (); |
| } |
| |
| /* Find bit tests of given CLUSTERS, where all members of the vector |
| are of type simple_cluster. New clusters are returned. */ |
| |
| vec<cluster *> |
| bit_test_cluster::find_bit_tests (vec<cluster *> &clusters) |
| { |
| if (!is_enabled ()) |
| return clusters.copy (); |
| |
| unsigned l = clusters.length (); |
| auto_vec<min_cluster_item> min; |
| min.reserve (l + 1); |
| |
| min.quick_push (min_cluster_item (0, 0, 0)); |
| |
| for (unsigned i = 1; i <= l; i++) |
| { |
| /* Set minimal # of clusters with i-th item to infinite. */ |
| min.quick_push (min_cluster_item (INT_MAX, INT_MAX, INT_MAX)); |
| |
| for (unsigned j = 0; j < i; j++) |
| { |
| if (min[j].m_count + 1 < min[i].m_count |
| && can_be_handled (clusters, j, i - 1)) |
| min[i] = min_cluster_item (min[j].m_count + 1, j, INT_MAX); |
| } |
| |
| gcc_checking_assert (min[i].m_count != INT_MAX); |
| } |
| |
| /* No result. */ |
| if (min[l].m_count == l) |
| return clusters.copy (); |
| |
| vec<cluster *> output; |
| output.create (4); |
| |
| /* Find and build the clusters. */ |
| for (unsigned end = l;;) |
| { |
| int start = min[end].m_start; |
| |
| if (is_beneficial (clusters, start, end - 1)) |
| { |
| bool entire = start == 0 && end == clusters.length (); |
| output.safe_push (new bit_test_cluster (clusters, start, end - 1, |
| entire)); |
| } |
| else |
| for (int i = end - 1; i >= start; i--) |
| output.safe_push (clusters[i]); |
| |
| end = start; |
| |
| if (start <= 0) |
| break; |
| } |
| |
| output.reverse (); |
| return output; |
| } |
| |
| /* Return true when RANGE of case values with UNIQ labels |
| can build a bit test. */ |
| |
| bool |
| bit_test_cluster::can_be_handled (unsigned HOST_WIDE_INT range, |
| unsigned int uniq) |
| { |
| /* Check overflow. */ |
| if (range == 0) |
| return false; |
| |
| if (range >= GET_MODE_BITSIZE (word_mode)) |
| return false; |
| |
| return uniq <= m_max_case_bit_tests; |
| } |
| |
| /* Return true when cluster starting at START and ending at END (inclusive) |
| can build a bit test. */ |
| |
| bool |
| bit_test_cluster::can_be_handled (const vec<cluster *> &clusters, |
| unsigned start, unsigned end) |
| { |
| auto_vec<int, m_max_case_bit_tests> dest_bbs; |
| /* For algorithm correctness, bit test for a single case must return |
| true. We bail out in is_beneficial if it's called just for |
| a single case. */ |
| if (start == end) |
| return true; |
| |
| unsigned HOST_WIDE_INT range = get_range (clusters[start]->get_low (), |
| clusters[end]->get_high ()); |
| |
| /* Make a guess first. */ |
| if (!can_be_handled (range, m_max_case_bit_tests)) |
| return false; |
| |
| for (unsigned i = start; i <= end; i++) |
| { |
| simple_cluster *sc = static_cast<simple_cluster *> (clusters[i]); |
| /* m_max_case_bit_tests is very small integer, thus the operation |
| is constant. */ |
| if (!dest_bbs.contains (sc->m_case_bb->index)) |
| { |
| if (dest_bbs.length () >= m_max_case_bit_tests) |
| return false; |
| dest_bbs.quick_push (sc->m_case_bb->index); |
| } |
| } |
| |
| return true; |
| } |
| |
| /* Return true when COUNT of cases of UNIQ labels is beneficial for bit test |
| transformation. */ |
| |
| bool |
| bit_test_cluster::is_beneficial (unsigned count, unsigned uniq) |
| { |
| return (((uniq == 1 && count >= 3) |
| || (uniq == 2 && count >= 5) |
| || (uniq == 3 && count >= 6))); |
| } |
| |
| /* Return true if cluster starting at START and ending at END (inclusive) |
| is profitable transformation. */ |
| |
| bool |
| bit_test_cluster::is_beneficial (const vec<cluster *> &clusters, |
| unsigned start, unsigned end) |
| { |
| /* Single case bail out. */ |
| if (start == end) |
| return false; |
| |
| auto_bitmap dest_bbs; |
| |
| for (unsigned i = start; i <= end; i++) |
| { |
| simple_cluster *sc = static_cast<simple_cluster *> (clusters[i]); |
| bitmap_set_bit (dest_bbs, sc->m_case_bb->index); |
| } |
| |
| unsigned uniq = bitmap_count_bits (dest_bbs); |
| unsigned count = end - start + 1; |
| return is_beneficial (count, uniq); |
| } |
| |
| /* Comparison function for qsort to order bit tests by decreasing |
| probability of execution. */ |
| |
| int |
| case_bit_test::cmp (const void *p1, const void *p2) |
| { |
| const case_bit_test *const d1 = (const case_bit_test *) p1; |
| const case_bit_test *const d2 = (const case_bit_test *) p2; |
| |
| if (d2->bits != d1->bits) |
| return d2->bits - d1->bits; |
| |
| /* Stabilize the sort. */ |
| return (LABEL_DECL_UID (CASE_LABEL (d2->label)) |
| - LABEL_DECL_UID (CASE_LABEL (d1->label))); |
| } |
| |
| /* Expand a switch statement by a short sequence of bit-wise |
| comparisons. "switch(x)" is effectively converted into |
| "if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are |
| integer constants. |
| |
| INDEX_EXPR is the value being switched on. |
| |
| MINVAL is the lowest case value of in the case nodes, |
| and RANGE is highest value minus MINVAL. MINVAL and RANGE |
| are not guaranteed to be of the same type as INDEX_EXPR |
| (the gimplifier doesn't change the type of case label values, |
| and MINVAL and RANGE are derived from those values). |
| MAXVAL is MINVAL + RANGE. |
| |
| There *MUST* be max_case_bit_tests or less unique case |
| node targets. */ |
| |
| void |
| bit_test_cluster::emit (tree index_expr, tree index_type, |
| tree, basic_block default_bb, location_t) |
| { |
| case_bit_test test[m_max_case_bit_tests] = { {} }; |
| unsigned int i, j, k; |
| unsigned int count; |
| |
| tree unsigned_index_type = range_check_type (index_type); |
| |
| gimple_stmt_iterator gsi; |
| gassign *shift_stmt; |
| |
| tree idx, tmp, csui; |
| tree word_type_node = lang_hooks.types.type_for_mode (word_mode, 1); |
| tree word_mode_zero = fold_convert (word_type_node, integer_zero_node); |
| tree word_mode_one = fold_convert (word_type_node, integer_one_node); |
| int prec = TYPE_PRECISION (word_type_node); |
| wide_int wone = wi::one (prec); |
| |
| tree minval = get_low (); |
| tree maxval = get_high (); |
| unsigned HOST_WIDE_INT bt_range = get_range (minval, maxval); |
| |
| /* Go through all case labels, and collect the case labels, profile |
| counts, and other information we need to build the branch tests. */ |
| count = 0; |
| for (i = 0; i < m_cases.length (); i++) |
| { |
| unsigned int lo, hi; |
| simple_cluster *n = static_cast<simple_cluster *> (m_cases[i]); |
| for (k = 0; k < count; k++) |
| if (n->m_case_bb == test[k].target_bb) |
| break; |
| |
| if (k == count) |
| { |
| gcc_checking_assert (count < m_max_case_bit_tests); |
| test[k].mask = wi::zero (prec); |
| test[k].target_bb = n->m_case_bb; |
| test[k].label = n->m_case_label_expr; |
| test[k].bits = 0; |
| count++; |
| } |
| |
| test[k].bits += n->get_range (n->get_low (), n->get_high ()); |
| |
| lo = tree_to_uhwi (int_const_binop (MINUS_EXPR, n->get_low (), minval)); |
| if (n->get_high () == NULL_TREE) |
| hi = lo; |
| else |
| hi = tree_to_uhwi (int_const_binop (MINUS_EXPR, n->get_high (), |
| minval)); |
| |
| for (j = lo; j <= hi; j++) |
| test[k].mask |= wi::lshift (wone, j); |
| } |
| |
| qsort (test, count, sizeof (*test), case_bit_test::cmp); |
| |
| /* If every possible relative value of the index expression is a valid shift |
| amount, then we can merge the entry test in the bit test. */ |
| wide_int min, max; |
| bool entry_test_needed; |
| if (TREE_CODE (index_expr) == SSA_NAME |
| && get_range_info (index_expr, &min, &max) == VR_RANGE |
| && wi::leu_p (max - min, prec - 1)) |
| { |
| tree index_type = TREE_TYPE (index_expr); |
| minval = fold_convert (index_type, minval); |
| wide_int iminval = wi::to_wide (minval); |
| if (wi::lt_p (min, iminval, TYPE_SIGN (index_type))) |
| { |
| minval = wide_int_to_tree (index_type, min); |
| for (i = 0; i < count; i++) |
| test[i].mask = wi::lshift (test[i].mask, iminval - min); |
| } |
| else if (wi::gt_p (min, iminval, TYPE_SIGN (index_type))) |
| { |
| minval = wide_int_to_tree (index_type, min); |
| for (i = 0; i < count; i++) |
| test[i].mask = wi::lrshift (test[i].mask, min - iminval); |
| } |
| maxval = wide_int_to_tree (index_type, max); |
| entry_test_needed = false; |
| } |
| else |
| entry_test_needed = true; |
| |
| /* 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, prec) < 0) |
| { |
| int cost_diff; |
| HOST_WIDE_INT m = tree_to_uhwi (minval); |
| rtx reg = gen_raw_REG (word_mode, 10000); |
| bool speed_p = optimize_insn_for_speed_p (); |
| cost_diff = set_src_cost (gen_rtx_PLUS (word_mode, reg, |
| GEN_INT (-m)), |
| word_mode, 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)); |
| } |
| } |
| |
| /* Now build the test-and-branch code. */ |
| |
| gsi = gsi_last_bb (m_case_bb); |
| |
| /* idx = (unsigned)x - minval. */ |
| idx = fold_convert (unsigned_index_type, index_expr); |
| idx = fold_build2 (MINUS_EXPR, unsigned_index_type, idx, |
| fold_convert (unsigned_index_type, minval)); |
| idx = force_gimple_operand_gsi (&gsi, idx, |
| /*simple=*/true, NULL_TREE, |
| /*before=*/true, GSI_SAME_STMT); |
| |
| if (m_handles_entire_switch && entry_test_needed) |
| { |
| tree range = int_const_binop (MINUS_EXPR, maxval, minval); |
| /* if (idx > range) goto default */ |
| range |
| = force_gimple_operand_gsi (&gsi, |
| fold_convert (unsigned_index_type, range), |
| /*simple=*/true, NULL_TREE, |
| /*before=*/true, GSI_SAME_STMT); |
| tmp = fold_build2 (GT_EXPR, boolean_type_node, idx, range); |
| basic_block new_bb |
| = hoist_edge_and_branch_if_true (&gsi, tmp, default_bb, |
| profile_probability::unlikely ()); |
| gsi = gsi_last_bb (new_bb); |
| } |
| |
| tmp = fold_build2 (LSHIFT_EXPR, word_type_node, word_mode_one, |
| fold_convert (word_type_node, idx)); |
| |
| /* csui = (1 << (word_mode) idx) */ |
| if (count > 1) |
| { |
| csui = make_ssa_name (word_type_node); |
| 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); |
| } |
| else |
| csui = tmp; |
| |
| profile_probability prob = profile_probability::always (); |
| |
| /* for each unique set of cases: |
| if (const & csui) goto target */ |
| for (k = 0; k < count; k++) |
| { |
| prob = profile_probability::always ().apply_scale (test[k].bits, |
| bt_range); |
| bt_range -= test[k].bits; |
| tmp = wide_int_to_tree (word_type_node, test[k].mask); |
| tmp = fold_build2 (BIT_AND_EXPR, word_type_node, csui, tmp); |
| tmp = fold_build2 (NE_EXPR, boolean_type_node, tmp, word_mode_zero); |
| tmp = force_gimple_operand_gsi (&gsi, tmp, |
| /*simple=*/true, NULL_TREE, |
| /*before=*/true, GSI_SAME_STMT); |
| basic_block new_bb |
| = hoist_edge_and_branch_if_true (&gsi, tmp, test[k].target_bb, prob); |
| 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. */ |
| edge e = make_edge (gsi_bb (gsi), default_bb, EDGE_FALLTHRU); |
| e->probability = profile_probability::always (); |
| } |
| |
| /* Split the basic block at the statement pointed to by GSIP, and insert |
| a branch to the target basic block of E_TRUE conditional on tree |
| expression COND. |
| |
| It is assumed that there is already an edge from the to-be-split |
| basic block to E_TRUE->dest block. This edge is removed, and the |
| profile information on the edge is re-used for the new conditional |
| jump. |
| |
| The CFG is updated. The dominator tree will not be valid after |
| this transformation, but the immediate dominators are updated if |
| UPDATE_DOMINATORS is true. |
| |
| Returns the newly created basic block. */ |
| |
| basic_block |
| bit_test_cluster::hoist_edge_and_branch_if_true (gimple_stmt_iterator *gsip, |
| tree cond, basic_block case_bb, |
| profile_probability prob) |
| { |
| tree tmp; |
| gcond *cond_stmt; |
| edge e_false; |
| basic_block new_bb, split_bb = gsi_bb (*gsip); |
| |
| edge e_true = make_edge (split_bb, case_bb, EDGE_TRUE_VALUE); |
| e_true->probability = prob; |
| gcc_assert (e_true->src == split_bb); |
| |
| tmp = force_gimple_operand_gsi (gsip, cond, /*simple=*/true, NULL, |
| /*before=*/true, GSI_SAME_STMT); |
| cond_stmt = gimple_build_cond_from_tree (tmp, NULL_TREE, NULL_TREE); |
| gsi_insert_before (gsip, cond_stmt, GSI_SAME_STMT); |
| |
| e_false = split_block (split_bb, cond_stmt); |
| new_bb = e_false->dest; |
| redirect_edge_pred (e_true, split_bb); |
| |
| e_false->flags &= ~EDGE_FALLTHRU; |
| e_false->flags |= EDGE_FALSE_VALUE; |
| e_false->probability = e_true->probability.invert (); |
| new_bb->count = e_false->count (); |
| |
| return new_bb; |
| } |
| |
| /* Compute the number of case labels that correspond to each outgoing edge of |
| switch statement. Record this information in the aux field of the edge. */ |
| |
| void |
| switch_decision_tree::compute_cases_per_edge () |
| { |
| reset_out_edges_aux (m_switch); |
| int ncases = gimple_switch_num_labels (m_switch); |
| for (int i = ncases - 1; i >= 1; --i) |
| { |
| edge case_edge = gimple_switch_edge (cfun, m_switch, i); |
| case_edge->aux = (void *) ((intptr_t) (case_edge->aux) + 1); |
| } |
| } |
| |
| /* Analyze switch statement and return true when the statement is expanded |
| as decision tree. */ |
| |
| bool |
| switch_decision_tree::analyze_switch_statement () |
| { |
| unsigned l = gimple_switch_num_labels (m_switch); |
| basic_block bb = gimple_bb (m_switch); |
| auto_vec<cluster *> clusters; |
| clusters.create (l - 1); |
| |
| basic_block default_bb = gimple_switch_default_bb (cfun, m_switch); |
| m_case_bbs.reserve (l); |
| m_case_bbs.quick_push (default_bb); |
| |
| compute_cases_per_edge (); |
| |
| for (unsigned i = 1; i < l; i++) |
| { |
| tree elt = gimple_switch_label (m_switch, i); |
| tree lab = CASE_LABEL (elt); |
| basic_block case_bb = label_to_block (cfun, lab); |
| edge case_edge = find_edge (bb, case_bb); |
| tree low = CASE_LOW (elt); |
| tree high = CASE_HIGH (elt); |
| |
| profile_probability p |
| = case_edge->probability.apply_scale (1, (intptr_t) (case_edge->aux)); |
| clusters.quick_push (new simple_cluster (low, high, elt, case_edge->dest, |
| p)); |
| m_case_bbs.quick_push (case_edge->dest); |
| } |
| |
| reset_out_edges_aux (m_switch); |
| |
| /* Find bit-test clusters. */ |
| vec<cluster *> output = bit_test_cluster::find_bit_tests (clusters); |
| |
| /* Find jump table clusters. */ |
| vec<cluster *> output2; |
| auto_vec<cluster *> tmp; |
| output2.create (1); |
| tmp.create (1); |
| |
| for (unsigned i = 0; i < output.length (); i++) |
| { |
| cluster *c = output[i]; |
| if (c->get_type () != SIMPLE_CASE) |
| { |
| if (!tmp.is_empty ()) |
| { |
| vec<cluster *> n = jump_table_cluster::find_jump_tables (tmp); |
| output2.safe_splice (n); |
| n.release (); |
| tmp.truncate (0); |
| } |
| output2.safe_push (c); |
| } |
| else |
| tmp.safe_push (c); |
| } |
| |
| /* We still can have a temporary vector to test. */ |
| if (!tmp.is_empty ()) |
| { |
| vec<cluster *> n = jump_table_cluster::find_jump_tables (tmp); |
| output2.safe_splice (n); |
| n.release (); |
| } |
| |
| if (dump_file) |
| { |
| fprintf (dump_file, ";; GIMPLE switch case clusters: "); |
| for (unsigned i = 0; i < output2.length (); i++) |
| output2[i]->dump (dump_file, dump_flags & TDF_DETAILS); |
| fprintf (dump_file, "\n"); |
| } |
| |
| output.release (); |
| |
| bool expanded = try_switch_expansion (output2); |
| release_clusters (output2); |
| return expanded; |
| } |
| |
| /* Attempt to expand CLUSTERS as a decision tree. Return true when |
| expanded. */ |
| |
| bool |
| switch_decision_tree::try_switch_expansion (vec<cluster *> &clusters) |
| { |
| tree index_expr = gimple_switch_index (m_switch); |
| tree index_type = TREE_TYPE (index_expr); |
| basic_block bb = gimple_bb (m_switch); |
| |
| if (gimple_switch_num_labels (m_switch) == 1 |
| || range_check_type (index_type) == NULL_TREE) |
| return false; |
| |
| /* Find the default case target label. */ |
| edge default_edge = gimple_switch_default_edge (cfun, m_switch); |
| m_default_bb = default_edge->dest; |
| |
| /* Do the insertion of a case label into m_case_list. The labels are |
| fed to us in descending order from the sorted vector of case labels used |
| in the tree part of the middle end. So the list we construct is |
| sorted in ascending order. */ |
| |
| for (int i = clusters.length () - 1; i >= 0; i--) |
| { |
| case_tree_node *r = m_case_list; |
| m_case_list = m_case_node_pool.allocate (); |
| m_case_list->m_right = r; |
| m_case_list->m_c = clusters[i]; |
| } |
| |
| record_phi_operand_mapping (); |
| |
| /* Split basic block that contains the gswitch statement. */ |
| gimple_stmt_iterator gsi = gsi_last_bb (bb); |
| edge e; |
| if (gsi_end_p (gsi)) |
| e = split_block_after_labels (bb); |
| else |
| { |
| gsi_prev (&gsi); |
| e = split_block (bb, gsi_stmt (gsi)); |
| } |
| bb = split_edge (e); |
| |
| /* Create new basic blocks for non-case clusters where specific expansion |
| needs to happen. */ |
| for (unsigned i = 0; i < clusters.length (); i++) |
| if (clusters[i]->get_type () != SIMPLE_CASE) |
| { |
| clusters[i]->m_case_bb = create_empty_bb (bb); |
| clusters[i]->m_case_bb->count = bb->count; |
| clusters[i]->m_case_bb->loop_father = bb->loop_father; |
| } |
| |
| /* Do not do an extra work for a single cluster. */ |
| if (clusters.length () == 1 |
| && clusters[0]->get_type () != SIMPLE_CASE) |
| { |
| cluster *c = clusters[0]; |
| c->emit (index_expr, index_type, |
| gimple_switch_default_label (m_switch), m_default_bb, |
| gimple_location (m_switch)); |
| redirect_edge_succ (single_succ_edge (bb), c->m_case_bb); |
| } |
| else |
| { |
| emit (bb, index_expr, default_edge->probability, index_type); |
| |
| /* Emit cluster-specific switch handling. */ |
| for (unsigned i = 0; i < clusters.length (); i++) |
| if (clusters[i]->get_type () != SIMPLE_CASE) |
| clusters[i]->emit (index_expr, index_type, |
| gimple_switch_default_label (m_switch), |
| m_default_bb, gimple_location (m_switch)); |
| } |
| |
| fix_phi_operands_for_edges (); |
| |
| return true; |
| } |
| |
| /* Before switch transformation, record all SSA_NAMEs defined in switch BB |
| and used in a label basic block. */ |
| |
| void |
| switch_decision_tree::record_phi_operand_mapping () |
| { |
| basic_block switch_bb = gimple_bb (m_switch); |
| /* Record all PHI nodes that have to be fixed after conversion. */ |
| for (unsigned i = 0; i < m_case_bbs.length (); i++) |
| { |
| gphi_iterator gsi; |
| basic_block bb = m_case_bbs[i]; |
| for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi = gsi.phi (); |
| |
| for (unsigned i = 0; i < gimple_phi_num_args (phi); i++) |
| { |
| basic_block phi_src_bb = gimple_phi_arg_edge (phi, i)->src; |
| if (phi_src_bb == switch_bb) |
| { |
| tree def = gimple_phi_arg_def (phi, i); |
| tree result = gimple_phi_result (phi); |
| m_phi_mapping.put (result, def); |
| break; |
| } |
| } |
| } |
| } |
| } |
| |
| /* Append new operands to PHI statements that were introduced due to |
| addition of new edges to case labels. */ |
| |
| void |
| switch_decision_tree::fix_phi_operands_for_edges () |
| { |
| gphi_iterator gsi; |
| |
| for (unsigned i = 0; i < m_case_bbs.length (); i++) |
| { |
| basic_block bb = m_case_bbs[i]; |
| for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| { |
| gphi *phi = gsi.phi (); |
| for (unsigned j = 0; j < gimple_phi_num_args (phi); j++) |
| { |
| tree def = gimple_phi_arg_def (phi, j); |
| if (def == NULL_TREE) |
| { |
| edge e = gimple_phi_arg_edge (phi, j); |
| tree *definition |
| = m_phi_mapping.get (gimple_phi_result (phi)); |
| gcc_assert (definition); |
| add_phi_arg (phi, *definition, e, UNKNOWN_LOCATION); |
| } |
| } |
| } |
| } |
| } |
| |
| /* Generate a decision tree, switching on INDEX_EXPR and jumping to |
| one of the labels in CASE_LIST or to the DEFAULT_LABEL. |
| |
| We generate a binary decision tree to select the appropriate target |
| code. */ |
| |
| void |
| switch_decision_tree::emit (basic_block bb, tree index_expr, |
| profile_probability default_prob, tree index_type) |
| { |
| balance_case_nodes (&m_case_list, NULL); |
| |
| if (dump_file) |
| dump_function_to_file (current_function_decl, dump_file, dump_flags); |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| int indent_step = ceil_log2 (TYPE_PRECISION (index_type)) + 2; |
| fprintf (dump_file, ";; Expanding GIMPLE switch as decision tree:\n"); |
| gcc_assert (m_case_list != NULL); |
| dump_case_nodes (dump_file, m_case_list, indent_step, 0); |
| } |
| |
| bb = emit_case_nodes (bb, index_expr, m_case_list, default_prob, index_type, |
| gimple_location (m_switch)); |
| |
| if (bb) |
| emit_jump (bb, m_default_bb); |
| |
| /* Remove all edges and do just an edge that will reach default_bb. */ |
| bb = gimple_bb (m_switch); |
| gimple_stmt_iterator gsi = gsi_last_bb (bb); |
| gsi_remove (&gsi, true); |
| |
| delete_basic_block (bb); |
| } |
| |
| /* Take an ordered list of case nodes |
| 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. */ |
| |
| void |
| switch_decision_tree::balance_case_nodes (case_tree_node **head, |
| case_tree_node *parent) |
| { |
| case_tree_node *np; |
| |
| np = *head; |
| if (np) |
| { |
| int i = 0; |
| int ranges = 0; |
| case_tree_node **npp; |
| case_tree_node *left; |
| profile_probability prob = profile_probability::never (); |
| |
| /* Count the number of entries on branch. Also count the ranges. */ |
| |
| while (np) |
| { |
| if (!tree_int_cst_equal (np->m_c->get_low (), np->m_c->get_high ())) |
| ranges++; |
| |
| i++; |
| prob += np->m_c->m_prob; |
| np = np->m_right; |
| } |
| |
| if (i > 2) |
| { |
| /* Split this list if it is long enough for that to help. */ |
| npp = head; |
| left = *npp; |
| profile_probability pivot_prob = prob.apply_scale (1, 2); |
| |
| /* Find the place in the list that bisects the list's total cost, |
| where ranges count as 2. */ |
| while (1) |
| { |
| /* Skip nodes while their probability does not reach |
| that amount. */ |
| prob -= (*npp)->m_c->m_prob; |
| if ((prob.initialized_p () && prob < pivot_prob) |
| || ! (*npp)->m_right) |
| break; |
| npp = &(*npp)->m_right; |
| } |
| |
| np = *npp; |
| *npp = 0; |
| *head = np; |
| np->m_parent = parent; |
| np->m_left = left == np ? NULL : left; |
| |
| /* Optimize each of the two split parts. */ |
| balance_case_nodes (&np->m_left, np); |
| balance_case_nodes (&np->m_right, np); |
| np->m_c->m_subtree_prob = np->m_c->m_prob; |
| if (np->m_left) |
| np->m_c->m_subtree_prob += np->m_left->m_c->m_subtree_prob; |
| if (np->m_right) |
| np->m_c->m_subtree_prob += np->m_right->m_c->m_subtree_prob; |
| } |
| else |
| { |
| /* Else leave this branch as one level, |
| but fill in `parent' fields. */ |
| np = *head; |
| np->m_parent = parent; |
| np->m_c->m_subtree_prob = np->m_c->m_prob; |
| for (; np->m_right; np = np->m_right) |
| { |
| np->m_right->m_parent = np; |
| (*head)->m_c->m_subtree_prob += np->m_right->m_c->m_subtree_prob; |
| } |
| } |
| } |
| } |
| |
| /* Dump ROOT, a list or tree of case nodes, to file. */ |
| |
| void |
| switch_decision_tree::dump_case_nodes (FILE *f, case_tree_node *root, |
| int indent_step, int indent_level) |
| { |
| if (root == 0) |
| return; |
| indent_level++; |
| |
| dump_case_nodes (f, root->m_left, indent_step, indent_level); |
| |
| fputs (";; ", f); |
| fprintf (f, "%*s", indent_step * indent_level, ""); |
| root->m_c->dump (f); |
| root->m_c->m_prob.dump (f); |
| fputs (" subtree: ", f); |
| root->m_c->m_subtree_prob.dump (f); |
| fputs (")\n", f); |
| |
| dump_case_nodes (f, root->m_right, indent_step, indent_level); |
| } |
| |
| |
| /* Add an unconditional jump to CASE_BB that happens in basic block BB. */ |
| |
| void |
| switch_decision_tree::emit_jump (basic_block bb, basic_block case_bb) |
| { |
| edge e = single_succ_edge (bb); |
| redirect_edge_succ (e, case_bb); |
| } |
| |
| /* Generate code to compare OP0 with OP1 so that the condition codes are |
| set and to jump to LABEL_BB if the condition is true. |
| COMPARISON is the GIMPLE comparison (EQ, NE, GT, etc.). |
| PROB is the probability of jumping to LABEL_BB. */ |
| |
| basic_block |
| switch_decision_tree::emit_cmp_and_jump_insns (basic_block bb, tree op0, |
| tree op1, tree_code comparison, |
| basic_block label_bb, |
| profile_probability prob, |
| location_t loc) |
| { |
| // TODO: it's once called with lhs != index. |
| op1 = fold_convert (TREE_TYPE (op0), op1); |
| |
| gcond *cond = gimple_build_cond (comparison, op0, op1, NULL_TREE, NULL_TREE); |
| gimple_set_location (cond, loc); |
| 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); |
| true_edge->probability = prob; |
| |
| return false_edge->dest; |
| } |
| |
| /* Generate code to jump to LABEL if OP0 and OP1 are equal. |
| PROB is the probability of jumping to LABEL_BB. |
| BB is a basic block where the new condition will be placed. */ |
| |
| basic_block |
| switch_decision_tree::do_jump_if_equal (basic_block bb, tree op0, tree op1, |
| basic_block label_bb, |
| profile_probability prob, |
| location_t loc) |
| { |
| op1 = fold_convert (TREE_TYPE (op0), op1); |
| |
| gcond *cond = gimple_build_cond (EQ_EXPR, op0, op1, NULL_TREE, NULL_TREE); |
| gimple_set_location (cond, loc); |
| 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); |
| true_edge->probability = prob; |
| |
| return false_edge->dest; |
| } |
| |
| /* Emit step-by-step code to select a case for the value of INDEX. |
| The thus generated decision tree follows the form of the |
| case-node binary tree NODE, whose nodes represent test conditions. |
| DEFAULT_PROB is probability of cases leading to default BB. |
| INDEX_TYPE is the type of the index of the switch. */ |
| |
| basic_block |
| switch_decision_tree::emit_case_nodes (basic_block bb, tree index, |
| case_tree_node *node, |
| profile_probability default_prob, |
| tree index_type, location_t loc) |
| { |
| profile_probability p; |
| |
| /* If node is null, we are done. */ |
| if (node == NULL) |
| return bb; |
| |
| /* Single value case. */ |
| if (node->m_c->is_single_value_p ()) |
| { |
| /* Node is single valued. First see if the index expression matches |
| this node and then check our children, if any. */ |
| p = node->m_c->m_prob / (node->m_c->m_subtree_prob + default_prob); |
| bb = do_jump_if_equal (bb, index, node->m_c->get_low (), |
| node->m_c->m_case_bb, p, loc); |
| /* Since this case is taken at this point, reduce its weight from |
| subtree_weight. */ |
| node->m_c->m_subtree_prob -= p; |
| |
| if (node->m_left != NULL && node->m_right != NULL) |
| { |
| /* 1) the node has both children |
| |
| If both children are single-valued cases with no |
| children, finish up all the work. This way, we can save |
| one ordered comparison. */ |
| |
| if (!node->m_left->has_child () |
| && node->m_left->m_c->is_single_value_p () |
| && !node->m_right->has_child () |
| && node->m_right->m_c->is_single_value_p ()) |
| { |
| p = (node->m_right->m_c->m_prob |
| / (node->m_c->m_subtree_prob + default_prob)); |
| bb = do_jump_if_equal (bb, index, node->m_right->m_c->get_low (), |
| node->m_right->m_c->m_case_bb, p, loc); |
| |
| p = (node->m_left->m_c->m_prob |
| / (node->m_c->m_subtree_prob + default_prob)); |
| bb = do_jump_if_equal (bb, index, node->m_left->m_c->get_low (), |
| node->m_left->m_c->m_case_bb, p, loc); |
| } |
| else |
| { |
| /* Branch to a label where we will handle it later. */ |
| basic_block test_bb = split_edge (single_succ_edge (bb)); |
| redirect_edge_succ (single_pred_edge (test_bb), |
| single_succ_edge (bb)->dest); |
| |
| p = ((node->m_right->m_c->m_subtree_prob |
| + default_prob.apply_scale (1, 2)) |
| / (node->m_c->m_subtree_prob + default_prob)); |
| bb = emit_cmp_and_jump_insns (bb, index, node->m_c->get_high (), |
| GT_EXPR, test_bb, p, loc); |
| default_prob = default_prob.apply_scale (1, 2); |
| |
| /* Handle the left-hand subtree. */ |
| bb = emit_case_nodes (bb, index, node->m_left, |
| default_prob, index_type, loc); |
| |
| /* If the left-hand subtree fell through, |
| don't let it fall into the right-hand subtree. */ |
| if (bb && m_default_bb) |
| emit_jump (bb, m_default_bb); |
| |
| bb = emit_case_nodes (test_bb, index, node->m_right, |
| default_prob, index_type, loc); |
| } |
| } |
| else if (node->m_left == NULL && node->m_right != NULL) |
| { |
| /* 2) the node has only right child. */ |
| |
| /* 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->m_right->has_child () |
| || !node->m_right->m_c->is_single_value_p ()) |
| { |
| p = (default_prob.apply_scale (1, 2) |
| / (node->m_c->m_subtree_prob + default_prob)); |
| bb = emit_cmp_and_jump_insns (bb, index, node->m_c->get_low (), |
| LT_EXPR, m_default_bb, p, loc); |
| default_prob = default_prob.apply_scale (1, 2); |
| |
| bb = emit_case_nodes (bb, index, node->m_right, default_prob, |
| index_type, loc); |
| } |
| else |
| { |
| /* 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. */ |
| p = (node->m_right->m_c->m_subtree_prob |
| / (node->m_c->m_subtree_prob + default_prob)); |
| bb = do_jump_if_equal (bb, index, node->m_right->m_c->get_low (), |
| node->m_right->m_c->m_case_bb, p, loc); |
| } |
| } |
| else if (node->m_left != NULL && node->m_right == NULL) |
| { |
| /* 3) just one subtree, on the left. Similar case as previous. */ |
| |
| if (node->m_left->has_child () |
| || !node->m_left->m_c->is_single_value_p ()) |
| { |
| p = (default_prob.apply_scale (1, 2) |
| / (node->m_c->m_subtree_prob + default_prob)); |
| bb = emit_cmp_and_jump_insns (bb, index, node->m_c->get_high (), |
| GT_EXPR, m_default_bb, p, loc); |
| default_prob = default_prob.apply_scale (1, 2); |
| |
| bb = emit_case_nodes (bb, index, node->m_left, default_prob, |
| index_type, loc); |
| } |
| else |
| { |
| /* 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. */ |
| p = (node->m_left->m_c->m_subtree_prob |
| / (node->m_c->m_subtree_prob + default_prob)); |
| bb = do_jump_if_equal (bb, index, node->m_left->m_c->get_low (), |
| node->m_left->m_c->m_case_bb, p, loc); |
| } |
| } |
| } |
| 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->has_child () || node->m_c->get_type () != SIMPLE_CASE) |
| { |
| /* Branch to a label where we will handle it later. */ |
| basic_block test_bb = split_edge (single_succ_edge (bb)); |
| redirect_edge_succ (single_pred_edge (test_bb), |
| single_succ_edge (bb)->dest); |
| |
| |
| profile_probability right_prob = profile_probability::never (); |
| if (node->m_right) |
| right_prob = node->m_right->m_c->m_subtree_prob; |
| p = ((right_prob + default_prob.apply_scale (1, 2)) |
| / (node->m_c->m_subtree_prob + default_prob)); |
| |
| bb = emit_cmp_and_jump_insns (bb, index, node->m_c->get_high (), |
| GT_EXPR, test_bb, p, loc); |
| default_prob = default_prob.apply_scale (1, 2); |
| |
| /* Value belongs to this node or to the left-hand subtree. */ |
| p = node->m_c->m_prob / (node->m_c->m_subtree_prob + default_prob); |
| bb = emit_cmp_and_jump_insns (bb, index, node->m_c->get_low (), |
| GE_EXPR, node->m_c->m_case_bb, p, loc); |
| |
| /* Handle the left-hand subtree. */ |
| bb = emit_case_nodes (bb, index, node->m_left, |
| default_prob, index_type, loc); |
| |
| /* If the left-hand subtree fell through, |
| don't let it fall into the right-hand subtree. */ |
| if (bb && m_default_bb) |
| emit_jump (bb, m_default_bb); |
| |
| bb = emit_case_nodes (test_bb, index, node->m_right, |
| default_prob, index_type, loc); |
| } |
| 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. */ |
| tree lhs, rhs; |
| generate_range_test (bb, index, node->m_c->get_low (), |
| node->m_c->get_high (), &lhs, &rhs); |
| p = default_prob / (node->m_c->m_subtree_prob + default_prob); |
| |
| bb = emit_cmp_and_jump_insns (bb, lhs, rhs, GT_EXPR, |
| m_default_bb, p, loc); |
| |
| emit_jump (bb, node->m_c->m_case_bb); |
| return NULL; |
| } |
| } |
| |
| return bb; |
| } |
| |
| /* 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; |
| bool cfg_altered = 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); |
| } |
| |
| switch_conversion sconv; |
| sconv.expand (as_a <gswitch *> (stmt)); |
| cfg_altered |= sconv.m_cfg_altered; |
| if (!sconv.m_reason) |
| { |
| if (dump_file) |
| { |
| fputs ("Switch converted\n", dump_file); |
| fputs ("--------------------------------\n", dump_file); |
| } |
| |
| /* Make no effort to update the post-dominator tree. |
| It is actually not that hard for the transformations |
| we have performed, but it is not supported |
| by iterate_fix_dominators. */ |
| free_dominance_info (CDI_POST_DOMINATORS); |
| } |
| else |
| { |
| if (dump_file) |
| { |
| fputs ("Bailing out - ", dump_file); |
| fputs (sconv.m_reason, dump_file); |
| fputs ("\n--------------------------------\n", dump_file); |
| } |
| } |
| } |
| } |
| |
| return cfg_altered ? TODO_cleanup_cfg : 0;; |
| } |
| |
| } // anon namespace |
| |
| gimple_opt_pass * |
| make_pass_convert_switch (gcc::context *ctxt) |
| { |
| return new pass_convert_switch (ctxt); |
| } |
| |
| /* The main function of the pass scans statements for switches and invokes |
| process_switch on them. */ |
| |
| namespace { |
| |
| template <bool O0> class pass_lower_switch: public gimple_opt_pass |
| { |
| public: |
| pass_lower_switch (gcc::context *ctxt) : gimple_opt_pass (data, ctxt) {} |
| |
| static const pass_data data; |
| opt_pass * |
| clone () |
| { |
| return new pass_lower_switch<O0> (m_ctxt); |
| } |
| |
| virtual bool |
| gate (function *) |
| { |
| return !O0 || !optimize; |
| } |
| |
| virtual unsigned int execute (function *fun); |
| }; // class pass_lower_switch |
| |
| template <bool O0> |
| const pass_data pass_lower_switch<O0>::data = { |
| GIMPLE_PASS, /* type */ |
| O0 ? "switchlower_O0" : "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 */ |
| }; |
| |
| template <bool O0> |
| unsigned int |
| pass_lower_switch<O0>::execute (function *fun) |
| { |
| basic_block bb; |
| bool expanded = false; |
| |
| auto_vec<gimple *> switch_statements; |
| switch_statements.create (1); |
| |
| FOR_EACH_BB_FN (bb, fun) |
| { |
| gimple *stmt = last_stmt (bb); |
| gswitch *swtch; |
| if (stmt && (swtch = dyn_cast<gswitch *> (stmt))) |
| { |
| if (!O0) |
| group_case_labels_stmt (swtch); |
| switch_statements.safe_push (swtch); |
| } |
| } |
| |
| for (unsigned i = 0; i < switch_statements.length (); i++) |
| { |
| gimple *stmt = switch_statements[i]; |
| 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); |
| } |
| |
| gswitch *swtch = dyn_cast<gswitch *> (stmt); |
| if (swtch) |
| { |
| switch_decision_tree dt (swtch); |
| expanded |= dt.analyze_switch_statement (); |
| } |
| } |
| |
| 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_O0 (gcc::context *ctxt) |
| { |
| return new pass_lower_switch<true> (ctxt); |
| } |
| gimple_opt_pass * |
| make_pass_lower_switch (gcc::context *ctxt) |
| { |
| return new pass_lower_switch<false> (ctxt); |
| } |