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131
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1 /* Support routines for Value Range Propagation (VRP).
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2 Copyright (C) 2016-2018 Free Software Foundation, Inc.
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3
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4 This file is part of GCC.
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5
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6 GCC is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3, or (at your option)
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9 any later version.
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10
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11 GCC is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with GCC; see the file COPYING3. If not see
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18 <http://www.gnu.org/licenses/>. */
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19
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20 #ifndef GCC_VR_VALUES_H
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21 #define GCC_VR_VALUES_H
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22
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23 /* The VR_VALUES class holds the current view of range information
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24 for all the SSA_NAMEs in the IL.
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25
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26 It can be used to hold context sensitive range information during
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27 a dominator walk or it may be used to hold range information in the
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28 standard VRP pass as ranges are propagated through the lattice to a
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29 steady state.
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30
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31 This information is independent of the range information that gets
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32 attached to SSA_NAMEs. A pass such as VRP may choose to transfer
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33 the global information it produces into global range information that
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34 gets attached to an SSA_NAME. It's unclear how useful that global
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35 information will be in a world where we can compute context sensitive
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36 range information fast or perform on-demand queries. */
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37 class vr_values
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38 {
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39 public:
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40 vr_values (void);
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41 ~vr_values (void);
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42
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43 value_range *get_value_range (const_tree);
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44
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45 void set_vr_value (tree, value_range *);
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46 void set_defs_to_varying (gimple *);
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47 bool update_value_range (const_tree, value_range *);
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48 tree op_with_constant_singleton_value_range (tree);
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49 void adjust_range_with_scev (value_range *, struct loop *, gimple *, tree);
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50 tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
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51 void dump_all_value_ranges (FILE *);
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52
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53 void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
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54 tree, tree, value_range *);
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55 void extract_range_from_phi_node (gphi *, value_range *);
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56 void extract_range_basic (value_range *, gimple *);
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57 void extract_range_from_stmt (gimple *, edge *, tree *, value_range *);
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58
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59 void vrp_visit_cond_stmt (gcond *, edge *);
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60
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61 void simplify_cond_using_ranges_2 (gcond *);
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62 bool simplify_stmt_using_ranges (gimple_stmt_iterator *);
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63
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64 /* Indicate that propagation through the lattice is complete. */
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65 void set_lattice_propagation_complete (void) { values_propagated = true; }
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66
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67 /* Allocate a new value_range object. */
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68 value_range *allocate_value_range (void)
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69 { return vrp_value_range_pool.allocate (); }
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70
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71 /* */
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72 void cleanup_edges_and_switches (void);
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73
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74 private:
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75 bool vrp_stmt_computes_nonzero (gimple *);
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76 bool op_with_boolean_value_range_p (tree);
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77 bool check_for_binary_op_overflow (enum tree_code, tree, tree, tree, bool *);
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78 value_range get_vr_for_comparison (int);
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79 tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool);
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80 tree compare_names (enum tree_code, tree, tree, bool *);
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81 bool two_valued_val_range_p (tree, tree *, tree *);
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82 tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
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83 tree, tree,
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84 bool *);
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85 tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code,
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86 tree, tree, bool,
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87 bool *, bool *);
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88 void extract_range_from_assignment (value_range *, gassign *);
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89 void extract_range_from_assert (value_range *, tree);
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90 void extract_range_from_ssa_name (value_range *, tree);
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91 void extract_range_from_binary_expr (value_range *, enum tree_code,
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92 tree, tree, tree);
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93 void extract_range_from_unary_expr (value_range *, enum tree_code,
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94 tree, tree);
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95 void extract_range_from_cond_expr (value_range *, gassign *);
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96 void extract_range_from_comparison (value_range *, enum tree_code,
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97 tree, tree, tree);
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98 void vrp_visit_assignment_or_call (gimple*, tree *, value_range *);
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99 void vrp_visit_switch_stmt (gswitch *, edge *);
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100 bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
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101 bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
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102 bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
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103 bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
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104 bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
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105 bool simplify_cond_using_ranges_1 (gcond *);
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106 bool simplify_switch_using_ranges (gswitch *);
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107 bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
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108 gimple *);
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109 bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);
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110
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111 /* Allocation pools for value_range objects. */
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112 object_allocator<value_range> vrp_value_range_pool;
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113
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114 /* This probably belongs in the lattice rather than in here. */
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115 bool values_propagated;
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116
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117 /* Allocations for equivalences all come from this obstack. */
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118 bitmap_obstack vrp_equiv_obstack;
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119
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120 /* Value range array. After propagation, VR_VALUE[I] holds the range
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121 of values that SSA name N_I may take. */
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122 unsigned int num_vr_values;
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123 value_range **vr_value;
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124
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125 /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
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126 number of executable edges we saw the last time we visited the
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127 node. */
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128 int *vr_phi_edge_counts;
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129
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130 /* Vectors of edges that need removing and switch statements that
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131 need updating. It is expected that a pass using the simplification
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132 routines will, at the end of the pass, clean up the edges and
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133 switch statements. The class dtor will try to detect cases
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134 that do not follow that expectation. */
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135 struct switch_update {
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136 gswitch *stmt;
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137 tree vec;
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138 };
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139
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140 vec<edge> to_remove_edges;
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141 vec<switch_update> to_update_switch_stmts;
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142 };
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143
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144 extern tree get_output_for_vrp (gimple *);
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145 #endif /* GCC_VR_VALUES_H */
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