gcc/range-op.h

   1 /* Header file for range operator class.
   2    Copyright (C) 2017-2021 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) const;
  56
  57   // Return the range for op[12] in the general case.  LHS is the range for
  58   // the LHS of the expression, OP[12]is the range for the other
  59   //
  60   // The operand and the result is returned in R.
  61   //
  62   // TYPE is the expected type of the range.
  63   //
  64   // Return TRUE if the operation is performed and a valid range is available.
  65   //
  66   // i.e.  [LHS] = ??? + OP2
  67   // is re-formed as R = [LHS] - OP2.
  68   virtual bool op1_range (irange &r, tree type,
  69                           const irange &lhs,
  70                           const irange &op2) const;
  71   virtual bool op2_range (irange &r, tree type,
  72                           const irange &lhs,
  73                           const irange &op1) const;
  74
  75 protected:
  76   // Perform an integral operation between 2 sub-ranges and return it.
  77   virtual void wi_fold (irange &r, tree type,
  78                         const wide_int &lh_lb,
  79                         const wide_int &lh_ub,
  80                         const wide_int &rh_lb,
  81                         const wide_int &rh_ub) const;
  82 };
  83
  84 extern range_operator *range_op_handler (enum tree_code code, tree type);
  85 extern void range_cast (irange &, tree type);
  86 extern void wi_set_zero_nonzero_bits (tree type,
  87                                       const wide_int &, const wide_int &,
  88                                       wide_int &maybe_nonzero,
  89                                       wide_int &mustbe_nonzero);
  90
  91 #endif // GCC_RANGE_OP_H