| 1 | /* expr.h -> header file for expr.c |
| 2 | Copyright (C) 1987-2018 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GAS, the GNU Assembler. |
| 5 | |
| 6 | GAS is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 3, or (at your option) |
| 9 | any later version. |
| 10 | |
| 11 | GAS is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with GAS; see the file COPYING. If not, write to the Free |
| 18 | Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA |
| 19 | 02110-1301, USA. */ |
| 20 | |
| 21 | /* |
| 22 | * By popular demand, we define a struct to represent an expression. |
| 23 | * This will no doubt mutate as expressions become baroque. |
| 24 | * |
| 25 | * Currently, we support expressions like "foo OP bar + 42". In other |
| 26 | * words we permit a (possibly undefined) symbol, a (possibly |
| 27 | * undefined) symbol and the operation used to combine the symbols, |
| 28 | * and an (absolute) augend. RMS says this is so we can have 1-pass |
| 29 | * assembly for any compiler emissions, and a 'case' statement might |
| 30 | * emit 'undefined1 - undefined2'. |
| 31 | * |
| 32 | * The type of an expression used to be stored as a segment. That got |
| 33 | * confusing because it overloaded the concept of a segment. I added |
| 34 | * an operator field, instead. |
| 35 | */ |
| 36 | |
| 37 | /* This is the type of an expression. The operator types are also |
| 38 | used while parsing an expression. |
| 39 | |
| 40 | NOTE: This enumeration must match the op_rank array in expr.c. */ |
| 41 | |
| 42 | typedef enum { |
| 43 | /* An illegal expression. */ |
| 44 | O_illegal, |
| 45 | /* A nonexistent expression. */ |
| 46 | O_absent, |
| 47 | /* X_add_number (a constant expression). */ |
| 48 | O_constant, |
| 49 | /* X_add_symbol + X_add_number. */ |
| 50 | O_symbol, |
| 51 | /* X_add_symbol + X_add_number - the base address of the image. */ |
| 52 | O_symbol_rva, |
| 53 | /* A register (X_add_number is register number). */ |
| 54 | O_register, |
| 55 | /* A big value. If X_add_number is negative or 0, the value is in |
| 56 | generic_floating_point_number. Otherwise the value is in |
| 57 | generic_bignum, and X_add_number is the number of LITTLENUMs in |
| 58 | the value. */ |
| 59 | O_big, |
| 60 | /* (- X_add_symbol) + X_add_number. */ |
| 61 | O_uminus, |
| 62 | /* (~ X_add_symbol) + X_add_number. */ |
| 63 | O_bit_not, |
| 64 | /* (! X_add_symbol) + X_add_number. */ |
| 65 | O_logical_not, |
| 66 | /* (X_add_symbol * X_op_symbol) + X_add_number. */ |
| 67 | O_multiply, |
| 68 | /* (X_add_symbol / X_op_symbol) + X_add_number. */ |
| 69 | O_divide, |
| 70 | /* (X_add_symbol % X_op_symbol) + X_add_number. */ |
| 71 | O_modulus, |
| 72 | /* (X_add_symbol << X_op_symbol) + X_add_number. */ |
| 73 | O_left_shift, |
| 74 | /* (X_add_symbol >> X_op_symbol) + X_add_number. */ |
| 75 | O_right_shift, |
| 76 | /* (X_add_symbol | X_op_symbol) + X_add_number. */ |
| 77 | O_bit_inclusive_or, |
| 78 | /* (X_add_symbol |~ X_op_symbol) + X_add_number. */ |
| 79 | O_bit_or_not, |
| 80 | /* (X_add_symbol ^ X_op_symbol) + X_add_number. */ |
| 81 | O_bit_exclusive_or, |
| 82 | /* (X_add_symbol & X_op_symbol) + X_add_number. */ |
| 83 | O_bit_and, |
| 84 | /* (X_add_symbol + X_op_symbol) + X_add_number. */ |
| 85 | O_add, |
| 86 | /* (X_add_symbol - X_op_symbol) + X_add_number. */ |
| 87 | O_subtract, |
| 88 | /* (X_add_symbol == X_op_symbol) + X_add_number. */ |
| 89 | O_eq, |
| 90 | /* (X_add_symbol != X_op_symbol) + X_add_number. */ |
| 91 | O_ne, |
| 92 | /* (X_add_symbol < X_op_symbol) + X_add_number. */ |
| 93 | O_lt, |
| 94 | /* (X_add_symbol <= X_op_symbol) + X_add_number. */ |
| 95 | O_le, |
| 96 | /* (X_add_symbol >= X_op_symbol) + X_add_number. */ |
| 97 | O_ge, |
| 98 | /* (X_add_symbol > X_op_symbol) + X_add_number. */ |
| 99 | O_gt, |
| 100 | /* (X_add_symbol && X_op_symbol) + X_add_number. */ |
| 101 | O_logical_and, |
| 102 | /* (X_add_symbol || X_op_symbol) + X_add_number. */ |
| 103 | O_logical_or, |
| 104 | /* X_op_symbol [ X_add_symbol ] */ |
| 105 | O_index, |
| 106 | /* machine dependent operators */ |
| 107 | O_md1, O_md2, O_md3, O_md4, O_md5, O_md6, O_md7, O_md8, |
| 108 | O_md9, O_md10, O_md11, O_md12, O_md13, O_md14, O_md15, O_md16, |
| 109 | O_md17, O_md18, O_md19, O_md20, O_md21, O_md22, O_md23, O_md24, |
| 110 | O_md25, O_md26, O_md27, O_md28, O_md29, O_md30, O_md31, O_md32, |
| 111 | /* this must be the largest value */ |
| 112 | O_max |
| 113 | } operatorT; |
| 114 | |
| 115 | typedef struct expressionS { |
| 116 | /* The main symbol. */ |
| 117 | symbolS *X_add_symbol; |
| 118 | /* The second symbol, if needed. */ |
| 119 | symbolS *X_op_symbol; |
| 120 | /* A number to add. */ |
| 121 | offsetT X_add_number; |
| 122 | |
| 123 | /* The type of the expression. We can't assume that an arbitrary |
| 124 | compiler can handle a bitfield of enum type. FIXME: We could |
| 125 | check this using autoconf. */ |
| 126 | #ifdef __GNUC__ |
| 127 | operatorT X_op : 8; |
| 128 | #else |
| 129 | unsigned char X_op; |
| 130 | #endif |
| 131 | |
| 132 | /* Non-zero if X_add_number should be regarded as unsigned. This is |
| 133 | only valid for O_constant expressions. It is only used when an |
| 134 | O_constant must be extended into a bignum (i.e., it is not used |
| 135 | when performing arithmetic on these values). |
| 136 | FIXME: This field is not set very reliably. */ |
| 137 | unsigned int X_unsigned : 1; |
| 138 | /* This is used to implement "word size + 1 bit" arithmetic, so that e.g. |
| 139 | expressions used with .sleb128 directives can use the full range available |
| 140 | for an unsigned word, but can also properly represent all values of a |
| 141 | signed word. */ |
| 142 | unsigned int X_extrabit : 1; |
| 143 | |
| 144 | /* 7 additional bits can be defined if needed. */ |
| 145 | |
| 146 | /* Machine dependent field */ |
| 147 | unsigned short X_md; |
| 148 | } expressionS; |
| 149 | |
| 150 | enum expr_mode |
| 151 | { |
| 152 | expr_evaluate, |
| 153 | expr_normal, |
| 154 | expr_defer |
| 155 | }; |
| 156 | |
| 157 | /* "result" should be type (expressionS *). */ |
| 158 | #define expression(result) expr (0, result, expr_normal) |
| 159 | #define expression_and_evaluate(result) expr (0, result, expr_evaluate) |
| 160 | #define deferred_expression(result) expr (0, result, expr_defer) |
| 161 | |
| 162 | /* If an expression is O_big, look here for its value. These common |
| 163 | data may be clobbered whenever expr() is called. */ |
| 164 | /* Flonums returned here. Big enough to hold most precise flonum. */ |
| 165 | extern FLONUM_TYPE generic_floating_point_number; |
| 166 | /* Bignums returned here. */ |
| 167 | extern LITTLENUM_TYPE generic_bignum[]; |
| 168 | /* Number of littlenums in above. */ |
| 169 | #define SIZE_OF_LARGE_NUMBER (20) |
| 170 | |
| 171 | typedef char operator_rankT; |
| 172 | |
| 173 | extern char get_symbol_name (char **); |
| 174 | extern char restore_line_pointer (char); |
| 175 | extern void expr_begin (void); |
| 176 | extern void expr_set_precedence (void); |
| 177 | extern void expr_set_rank (operatorT, operator_rankT); |
| 178 | extern void add_to_result (expressionS *, offsetT, int); |
| 179 | extern void subtract_from_result (expressionS *, offsetT, int); |
| 180 | extern segT expr (int, expressionS *, enum expr_mode); |
| 181 | extern unsigned int get_single_number (void); |
| 182 | extern symbolS *make_expr_symbol (expressionS * expressionP); |
| 183 | extern int expr_symbol_where (symbolS *, const char **, unsigned int *); |
| 184 | extern void current_location (expressionS *); |
| 185 | |
| 186 | extern symbolS *expr_build_uconstant (offsetT); |
| 187 | extern symbolS *expr_build_dot (void); |
| 188 | |
| 189 | int resolve_expression (expressionS *); |