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   friend class range_op_table;
  52 public:
  53   range_operator () : m_code (ERROR_MARK) { }
  54   // Perform an operation between 2 ranges and return it.
  55   virtual bool fold_range (irange &r, tree type,
  56                            const irange &lh,
  57                            const irange &rh,
  58                            relation_trio = TRIO_VARYING) const;
  59
  60   // Return the range for op[12] in the general case.  LHS is the range for
  61   // the LHS of the expression, OP[12]is the range for the other
  62   //
  63   // The operand and the result is returned in R.
  64   //
  65   // TYPE is the expected type of the range.
  66   //
  67   // Return TRUE if the operation is performed and a valid range is available.
  68   //
  69   // i.e.  [LHS] = ??? + OP2
  70   // is re-formed as R = [LHS] - OP2.
  71   virtual bool op1_range (irange &r, tree type,
  72                           const irange &lhs,
  73                           const irange &op2,
  74                           relation_trio = TRIO_VARYING) const;
  75   virtual bool op2_range (irange &r, tree type,
  76                           const irange &lhs,
  77                           const irange &op1,
  78                           relation_trio = TRIO_VARYING) const;
  79
  80   // The following routines are used to represent relations between the
  81   // various operations.  If the caller knows where the symbolics are,
  82   // it can query for relationships between them given known ranges.
  83   // the optional relation passed in is the relation between op1 and op2.
  84   virtual relation_kind lhs_op1_relation (const irange &lhs,
  85                                           const irange &op1,
  86                                           const irange &op2,
  87                                           relation_kind = VREL_VARYING) const;
  88   virtual relation_kind lhs_op2_relation (const irange &lhs,
  89                                           const irange &op1,
  90                                           const irange &op2,
  91                                           relation_kind = VREL_VARYING) const;
  92   virtual relation_kind op1_op2_relation (const irange &lhs) const;
  93 protected:
  94   // Perform an integral operation between 2 sub-ranges and return it.
  95   virtual void wi_fold (irange &r, tree type,
  96                         const wide_int &lh_lb,
  97                         const wide_int &lh_ub,
  98                         const wide_int &rh_lb,
  99                         const wide_int &rh_ub) const;
 100   // Effect of relation for generic fold_range clients.
 101   virtual bool op1_op2_relation_effect (irange &lhs_range, tree type,
 102                                         const irange &op1_range,
 103                                         const irange &op2_range,
 104                                         relation_kind rel) const;
 105   // Called by fold range to split small subranges into parts.
 106   void wi_fold_in_parts (irange &r, tree type,
 107                          const wide_int &lh_lb,
 108                          const wide_int &lh_ub,
 109                          const wide_int &rh_lb,
 110                          const wide_int &rh_ub) const;
 111
 112   // Tree code of the range operator or ERROR_MARK if unknown.
 113   tree_code m_code;
 114 };
 115
 116 // Like range_operator above, but for floating point operators.
 117
 118 class range_operator_float
 119 {
 120 public:
 121   virtual bool fold_range (frange &r, tree type,
 122                            const frange &lh,
 123                            const frange &rh,
 124                            relation_trio = TRIO_VARYING) const;
 125   virtual void rv_fold (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub,
 126                         bool &maybe_nan,
 127                         tree type,
 128                         const REAL_VALUE_TYPE &lh_lb,
 129                         const REAL_VALUE_TYPE &lh_ub,
 130                         const REAL_VALUE_TYPE &rh_lb,
 131                         const REAL_VALUE_TYPE &rh_ub,
 132                         relation_kind) const;
 133   // Unary operations have the range of the LHS as op2.
 134   virtual bool fold_range (irange &r, tree type,
 135                            const frange &lh,
 136                            const irange &rh,
 137                            relation_trio = TRIO_VARYING) const;
 138   virtual bool fold_range (irange &r, tree type,
 139                            const frange &lh,
 140                            const frange &rh,
 141                            relation_trio = TRIO_VARYING) const;
 142   virtual bool op1_range (frange &r, tree type,
 143                           const frange &lhs,
 144                           const frange &op2,
 145                           relation_trio = TRIO_VARYING) const;
 146   virtual bool op1_range (frange &r, tree type,
 147                           const irange &lhs,
 148                           const frange &op2,
 149                           relation_trio = TRIO_VARYING) const;
 150   virtual bool op2_range (frange &r, tree type,
 151                           const frange &lhs,
 152                           const frange &op1,
 153                           relation_trio = TRIO_VARYING) const;
 154   virtual bool op2_range (frange &r, tree type,
 155                           const irange &lhs,
 156                           const frange &op1,
 157                           relation_trio = TRIO_VARYING) const;
 158
 159   virtual relation_kind lhs_op1_relation (const frange &lhs,
 160                                           const frange &op1,
 161                                           const frange &op2,
 162                                           relation_kind = VREL_VARYING) const;
 163   virtual relation_kind lhs_op1_relation (const irange &lhs,
 164                                           const frange &op1,
 165                                           const frange &op2,
 166                                           relation_kind = VREL_VARYING) const;
 167   virtual relation_kind lhs_op2_relation (const frange &lhs,
 168                                           const frange &op1,
 169                                           const frange &op2,
 170                                           relation_kind = VREL_VARYING) const;
 171   virtual relation_kind lhs_op2_relation (const irange &lhs,
 172                                           const frange &op1,
 173                                           const frange &op2,
 174                                           relation_kind = VREL_VARYING) const;
 175   virtual relation_kind op1_op2_relation (const irange &lhs) const;
 176   virtual relation_kind op1_op2_relation (const frange &lhs) const;
 177 };
 178
 179 class range_op_handler
 180 {
 181 public:
 182   range_op_handler ();
 183   range_op_handler (enum tree_code code, tree type);
 184   inline operator bool () const { return m_valid; }
 185
 186   bool fold_range (vrange &r, tree type,
 187                    const vrange &lh,
 188                    const vrange &rh,
 189                    relation_trio = TRIO_VARYING) const;
 190   bool op1_range (vrange &r, tree type,
 191                   const vrange &lhs,
 192                   const vrange &op2,
 193                   relation_trio = TRIO_VARYING) const;
 194   bool op2_range (vrange &r, tree type,
 195                   const vrange &lhs,
 196                   const vrange &op1,
 197                   relation_trio = TRIO_VARYING) const;
 198   relation_kind lhs_op1_relation (const vrange &lhs,
 199                                   const vrange &op1,
 200                                   const vrange &op2,
 201                                   relation_kind = VREL_VARYING) const;
 202   relation_kind lhs_op2_relation (const vrange &lhs,
 203                                   const vrange &op1,
 204                                   const vrange &op2,
 205                                   relation_kind = VREL_VARYING) const;
 206   relation_kind op1_op2_relation (const vrange &lhs) const;
 207 protected:
 208   void set_op_handler (enum tree_code code, tree type);
 209   bool m_valid;
 210   range_operator *m_int;
 211   range_operator_float *m_float;
 212 };
 213
 214 extern bool range_cast (vrange &, tree type);
 215 extern void wi_set_zero_nonzero_bits (tree type,
 216                                       const wide_int &, const wide_int &,
 217                                       wide_int &maybe_nonzero,
 218                                       wide_int &mustbe_nonzero);
 219
 220 // op1_op2_relation methods that are the same across irange and frange.
 221 relation_kind equal_op1_op2_relation (const irange &lhs);
 222 relation_kind not_equal_op1_op2_relation (const irange &lhs);
 223 relation_kind lt_op1_op2_relation (const irange &lhs);
 224 relation_kind le_op1_op2_relation (const irange &lhs);
 225 relation_kind gt_op1_op2_relation (const irange &lhs);
 226 relation_kind ge_op1_op2_relation (const irange &lhs);
 227
 228 enum bool_range_state { BRS_FALSE, BRS_TRUE, BRS_EMPTY, BRS_FULL };
 229 bool_range_state get_bool_state (vrange &r, const vrange &lhs, tree val_type);
 230
 231 // If the range of either op1 or op2 is undefined, set the result to
 232 // varying and return TRUE.  If the caller truely cares about a result,
 233 // they should pass in a varying if it has an undefined that it wants
 234 // treated as a varying.
 235
 236 inline bool
 237 empty_range_varying (vrange &r, tree type,
 238                      const vrange &op1, const vrange & op2)
 239 {
 240   if (op1.undefined_p () || op2.undefined_p ())
 241     {
 242       r.set_varying (type);
 243       return true;
 244     }
 245   else
 246     return false;
 247 }
 248
 249 // For relation opcodes, first try to see if the supplied relation
 250 // forces a true or false result, and return that.
 251 // Then check for undefined operands.  If none of this applies,
 252 // return false.
 253
 254 inline bool
 255 relop_early_resolve (irange &r, tree type, const vrange &op1,
 256                      const vrange &op2, relation_trio trio,
 257                      relation_kind my_rel)
 258 {
 259   relation_kind rel = trio.op1_op2 ();
 260   // If known relation is a complete subset of this relation, always true.
 261   if (relation_union (rel, my_rel) == my_rel)
 262     {
 263       r = range_true (type);
 264       return true;
 265     }
 266
 267   // If known relation has no subset of this relation, always false.
 268   if (relation_intersect (rel, my_rel) == VREL_UNDEFINED)
 269     {
 270       r = range_false (type);
 271       return true;
 272     }
 273
 274   // If either operand is undefined, return VARYING.
 275   if (empty_range_varying (r, type, op1, op2))
 276     return true;
 277
 278   return false;
 279 }
 280
 281 // This implements the range operator tables as local objects.
 282
 283 class range_op_table
 284 {
 285 public:
 286   range_operator *operator[] (enum tree_code code);
 287 protected:
 288   void set (enum tree_code code, range_operator &op);
 289 private:
 290   range_operator *m_range_tree[MAX_TREE_CODES];
 291 };
 292
 293 // Like above, but for floating point operators.
 294
 295 class floating_op_table
 296 {
 297 public:
 298   floating_op_table ();
 299   range_operator_float *operator[] (enum tree_code code);
 300 private:
 301   void set (enum tree_code code, range_operator_float &op);
 302   range_operator_float *m_range_tree[MAX_TREE_CODES];
 303 };
 304
 305 // This holds the range op table for floating point operations.
 306 extern floating_op_table *floating_tree_table;
 307
 308 #endif // GCC_RANGE_OP_H