gcc/range-op.h

   1 /* Header file for range operator class.
   2    Copyright (C) 2017-2022 Free Software Foundation, Inc.
   3    Contributed by Andrew MacLeod <amacleod@redhat.com>
   4    and Aldy Hernandez <aldyh@redhat.com>.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16  for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef GCC_RANGE_OP_H
  23 #define GCC_RANGE_OP_H
  24
  25 // This class is implemented for each kind of operator supported by
  26 // the range generator.  It serves various purposes.
  27 //
  28 // 1 - Generates range information for the specific operation between
  29 //     two ranges.  This provides the ability to fold ranges for an
  30 //     expression.
  31 //
  32 // 2 - Performs range algebra on the expression such that a range can be
  33 //     adjusted in terms of one of the operands:
  34 //
  35 //       def = op1 + op2
  36 //
  37 //     Given a range for def, we can adjust the range so that it is in
  38 //     terms of either operand.
  39 //
  40 //     op1_range (def_range, op2) will adjust the range in place so it
  41 //     is in terms of op1.  Since op1 = def - op2, it will subtract
  42 //     op2 from each element of the range.
  43 //
  44 // 3 - Creates a range for an operand based on whether the result is 0 or
  45 //     non-zero.  This is mostly for logical true false, but can serve other
  46 //     purposes.
  47 //       ie   0 = op1 - op2 implies op2 has the same range as op1.
  48
  49 class range_operator
  50 {
  51 public:
  52   // Perform an operation between 2 ranges and return it.
  53   virtual bool fold_range (irange &r, tree type,
  54                            const irange &lh,
  55                            const irange &rh,
  56                            relation_kind rel = VREL_VARYING) const;
  57
  58   // Return the range for op[12] in the general case.  LHS is the range for
  59   // the LHS of the expression, OP[12]is the range for the other
  60   //
  61   // The operand and the result is returned in R.
  62   //
  63   // TYPE is the expected type of the range.
  64   //
  65   // Return TRUE if the operation is performed and a valid range is available.
  66   //
  67   // i.e.  [LHS] = ??? + OP2
  68   // is re-formed as R = [LHS] - OP2.
  69   virtual bool op1_range (irange &r, tree type,
  70                           const irange &lhs,
  71                           const irange &op2,
  72                           relation_kind rel = VREL_VARYING) const;
  73   virtual bool op2_range (irange &r, tree type,
  74                           const irange &lhs,
  75                           const irange &op1,
  76                           relation_kind rel = VREL_VARYING) const;
  77
  78   // The following routines are used to represent relations between the
  79   // various operations.  If the caller knows where the symbolics are,
  80   // it can query for relationships between them given known ranges.
  81   // the optional relation passed in is the relation between op1 and op2.
  82   virtual relation_kind lhs_op1_relation (const irange &lhs,
  83                                           const irange &op1,
  84                                           const irange &op2,
  85                                           relation_kind = VREL_VARYING) const;
  86   virtual relation_kind lhs_op2_relation (const irange &lhs,
  87                                           const irange &op1,
  88                                           const irange &op2,
  89                                           relation_kind = VREL_VARYING) const;
  90   virtual relation_kind op1_op2_relation (const irange &lhs) const;
  91 protected:
  92   // Perform an integral operation between 2 sub-ranges and return it.
  93   virtual void wi_fold (irange &r, tree type,
  94                         const wide_int &lh_lb,
  95                         const wide_int &lh_ub,
  96                         const wide_int &rh_lb,
  97                         const wide_int &rh_ub) const;
  98   // Effect of relation for generic fold_range clients.
  99   virtual bool op1_op2_relation_effect (irange &lhs_range, tree type,
 100                                         const irange &op1_range,
 101                                         const irange &op2_range,
 102                                         relation_kind rel) const;
 103   // Called by fold range to split small subranges into parts.
 104   void wi_fold_in_parts (irange &r, tree type,
 105                          const wide_int &lh_lb,
 106                          const wide_int &lh_ub,
 107                          const wide_int &rh_lb,
 108                          const wide_int &rh_ub) const;
 109 };
 110
 111 // Like range_operator above, but for floating point operators.
 112
 113 class range_operator_float
 114 {
 115 public:
 116   virtual bool fold_range (frange &r, tree type,
 117                            const frange &lh,
 118                            const frange &rh,
 119                            relation_kind rel = VREL_VARYING) const;
 120   // Unary operations have the range of the LHS as op2.
 121   virtual bool fold_range (irange &r, tree type,
 122                            const frange &lh,
 123                            const irange &rh,
 124                            relation_kind rel = VREL_VARYING) const;
 125   virtual bool fold_range (irange &r, tree type,
 126                            const frange &lh,
 127                            const frange &rh,
 128                            relation_kind rel = VREL_VARYING) const;
 129   virtual bool op1_range (frange &r, tree type,
 130                           const frange &lhs,
 131                           const frange &op2,
 132                           relation_kind rel = VREL_VARYING) const;
 133   virtual bool op1_range (frange &r, tree type,
 134                           const irange &lhs,
 135                           const frange &op2,
 136                           relation_kind rel = VREL_VARYING) const;
 137   virtual bool op2_range (frange &r, tree type,
 138                           const frange &lhs,
 139                           const frange &op1,
 140                           relation_kind rel = VREL_VARYING) const;
 141   virtual bool op2_range (frange &r, tree type,
 142                           const irange &lhs,
 143                           const frange &op1,
 144                           relation_kind rel = VREL_VARYING) const;
 145
 146   virtual relation_kind lhs_op1_relation (const frange &lhs,
 147                                           const frange &op1,
 148                                           const frange &op2,
 149                                           relation_kind = VREL_VARYING) const;
 150   virtual relation_kind lhs_op1_relation (const irange &lhs,
 151                                           const frange &op1,
 152                                           const frange &op2,
 153                                           relation_kind = VREL_VARYING) const;
 154   virtual relation_kind lhs_op2_relation (const frange &lhs,
 155                                           const frange &op1,
 156                                           const frange &op2,
 157                                           relation_kind = VREL_VARYING) const;
 158   virtual relation_kind lhs_op2_relation (const irange &lhs,
 159                                           const frange &op1,
 160                                           const frange &op2,
 161                                           relation_kind = VREL_VARYING) const;
 162   virtual relation_kind op1_op2_relation (const irange &lhs) const;
 163 };
 164
 165 class range_op_handler
 166 {
 167 public:
 168   range_op_handler ();
 169   range_op_handler (enum tree_code code, tree type);
 170   inline operator bool () const { return m_valid; }
 171
 172   bool fold_range (vrange &r, tree type,
 173                    const vrange &lh,
 174                    const vrange &rh,
 175                    relation_kind rel = VREL_VARYING) const;
 176   bool op1_range (vrange &r, tree type,
 177                   const vrange &lhs,
 178                   const vrange &op2,
 179                   relation_kind rel = VREL_VARYING) const;
 180   bool op2_range (vrange &r, tree type,
 181                   const vrange &lhs,
 182                   const vrange &op1,
 183                   relation_kind rel = VREL_VARYING) const;
 184   relation_kind lhs_op1_relation (const vrange &lhs,
 185                                   const vrange &op1,
 186                                   const vrange &op2,
 187                                   relation_kind = VREL_VARYING) const;
 188   relation_kind lhs_op2_relation (const vrange &lhs,
 189                                   const vrange &op1,
 190                                   const vrange &op2,
 191                                   relation_kind = VREL_VARYING) const;
 192   relation_kind op1_op2_relation (const vrange &lhs) const;
 193 protected:
 194   void set_op_handler (enum tree_code code, tree type);
 195   bool m_valid;
 196   range_operator *m_int;
 197   range_operator_float *m_float;
 198 };
 199
 200 extern bool range_cast (vrange &, tree type);
 201 extern void wi_set_zero_nonzero_bits (tree type,
 202                                       const wide_int &, const wide_int &,
 203                                       wide_int &maybe_nonzero,
 204                                       wide_int &mustbe_nonzero);
 205
 206 // op1_op2_relation methods that are the same across irange and frange.
 207 relation_kind equal_op1_op2_relation (const irange &lhs);
 208 relation_kind not_equal_op1_op2_relation (const irange &lhs);
 209 relation_kind lt_op1_op2_relation (const irange &lhs);
 210 relation_kind le_op1_op2_relation (const irange &lhs);
 211 relation_kind gt_op1_op2_relation (const irange &lhs);
 212 relation_kind ge_op1_op2_relation (const irange &lhs);
 213
 214 enum bool_range_state { BRS_FALSE, BRS_TRUE, BRS_EMPTY, BRS_FULL };
 215 bool_range_state get_bool_state (vrange &r, const vrange &lhs, tree val_type);
 216
 217 // If the range of either op1 or op2 is undefined, set the result to
 218 // varying and return TRUE.  If the caller truely cares about a result,
 219 // they should pass in a varying if it has an undefined that it wants
 220 // treated as a varying.
 221
 222 inline bool
 223 empty_range_varying (vrange &r, tree type,
 224                      const vrange &op1, const vrange & op2)
 225 {
 226   if (op1.undefined_p () || op2.undefined_p ())
 227     {
 228       r.set_varying (type);
 229       return true;
 230     }
 231   else
 232     return false;
 233 }
 234
 235 // For relation opcodes, first try to see if the supplied relation
 236 // forces a true or false result, and return that.
 237 // Then check for undefined operands.  If none of this applies,
 238 // return false.
 239
 240 inline bool
 241 relop_early_resolve (irange &r, tree type, const vrange &op1,
 242                      const vrange &op2, relation_kind rel,
 243                      relation_kind my_rel)
 244 {
 245   // If known relation is a complete subset of this relation, always true.
 246   if (relation_union (rel, my_rel) == my_rel)
 247     {
 248       r = range_true (type);
 249       return true;
 250     }
 251
 252   // If known relation has no subset of this relation, always false.
 253   if (relation_intersect (rel, my_rel) == VREL_UNDEFINED)
 254     {
 255       r = range_false (type);
 256       return true;
 257     }
 258
 259   // If either operand is undefined, return VARYING.
 260   if (empty_range_varying (r, type, op1, op2))
 261     return true;
 262
 263   return false;
 264 }
 265
 266 // This implements the range operator tables as local objects.
 267
 268 class range_op_table
 269 {
 270 public:
 271   range_operator *operator[] (enum tree_code code);
 272 protected:
 273   void set (enum tree_code code, range_operator &op);
 274 private:
 275   range_operator *m_range_tree[MAX_TREE_CODES];
 276 };
 277
 278 // Like above, but for floating point operators.
 279
 280 class floating_op_table
 281 {
 282 public:
 283   floating_op_table ();
 284   range_operator_float *operator[] (enum tree_code code);
 285 private:
 286   void set (enum tree_code code, range_operator_float &op);
 287   range_operator_float *m_range_tree[MAX_TREE_CODES];
 288 };
 289
 290 // This holds the range op table for floating point operations.
 291 extern floating_op_table *floating_tree_table;
 292
 293 #endif // GCC_RANGE_OP_H