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1 /* Header file for range operator class.
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2 Copyright (C) 2017-2020 Free Software Foundation, Inc.
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3 Contributed by Andrew MacLeod <amacleod@redhat.com>
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4 and Aldy Hernandez <aldyh@redhat.com>.
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5
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6 This file is part of GCC.
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7
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8 GCC is free software; you can redistribute it and/or modify it under
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9 the terms of the GNU General Public License as published by the Free
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10 Software Foundation; either version 3, or (at your option) any later
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11 version.
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12
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13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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16 for more details.
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17
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18 You should have received a copy of the GNU General Public License
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19 along with GCC; see the file COPYING3. If not see
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20 <http://www.gnu.org/licenses/>. */
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21
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22 #ifndef GCC_RANGE_OP_H
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23 #define GCC_RANGE_OP_H
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24
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25 // This class is implemented for each kind of operator supported by
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26 // the range generator. It serves various purposes.
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27 //
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28 // 1 - Generates range information for the specific operation between
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29 // two ranges. This provides the ability to fold ranges for an
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30 // expression.
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31 //
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32 // 2 - Performs range algebra on the expression such that a range can be
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33 // adjusted in terms of one of the operands:
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34 //
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35 // def = op1 + op2
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36 //
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37 // Given a range for def, we can adjust the range so that it is in
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38 // terms of either operand.
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39 //
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40 // op1_range (def_range, op2) will adjust the range in place so it
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41 // is in terms of op1. Since op1 = def - op2, it will subtract
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42 // op2 from each element of the range.
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43 //
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44 // 3 - Creates a range for an operand based on whether the result is 0 or
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45 // non-zero. This is mostly for logical true false, but can serve other
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46 // purposes.
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47 // ie 0 = op1 - op2 implies op2 has the same range as op1.
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48
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49 class range_operator
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50 {
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51 public:
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52 // Perform an operation between 2 ranges and return it.
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53 virtual bool fold_range (value_range &r, tree type,
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54 const value_range &lh,
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55 const value_range &rh) const;
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56
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57 // Return the range for op[12] in the general case. LHS is the range for
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58 // the LHS of the expression, OP[12]is the range for the other
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59 //
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60 // The operand and the result is returned in R.
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61 //
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62 // TYPE is the expected type of the range.
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63 //
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64 // Return TRUE if the operation is performed and a valid range is available.
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65 //
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66 // i.e. [LHS] = ??? + OP2
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67 // is re-formed as R = [LHS] - OP2.
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68 virtual bool op1_range (value_range &r, tree type,
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69 const value_range &lhs,
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70 const value_range &op2) const;
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71 virtual bool op2_range (value_range &r, tree type,
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72 const value_range &lhs,
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73 const value_range &op1) const;
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74
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75 protected:
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76 // Perform an integral operation between 2 sub-ranges and return it.
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77 virtual void wi_fold (value_range &r, tree type,
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78 const wide_int &lh_lb,
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79 const wide_int &lh_ub,
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80 const wide_int &rh_lb,
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81 const wide_int &rh_ub) const;
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82 };
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83
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84 extern range_operator *range_op_handler (enum tree_code code, tree type);
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85 extern void range_cast (value_range &, tree type);
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86 extern void wi_set_zero_nonzero_bits (tree type,
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87 const wide_int &, const wide_int &,
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88 wide_int &maybe_nonzero,
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89 wide_int &mustbe_nonzero);
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90
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91 #endif // GCC_RANGE_OP_H
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