gas/expr.h

   1 /* expr.h -> header file for expr.c
   2    Copyright (C) 1987-2023 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 /* By popular demand, we define a struct to represent an expression.
  22    This will no doubt mutate as expressions become baroque.
  23
  24    Currently, we support expressions like "foo OP bar + 42".  In other
  25    words we permit a (possibly undefined) symbol, a (possibly
  26    undefined) symbol and the operation used to combine the symbols,
  27    and an (absolute) augend.  RMS says this is so we can have 1-pass
  28    assembly for any compiler emissions, and a 'case' statement might
  29    emit 'undefined1 - undefined2'.
  30
  31    The type of an expression used to be stored as a segment.  That got
  32    confusing because it overloaded the concept of a segment.  I added
  33    an operator field, instead.  */
  34
  35 /* This is the type of an expression.  The operator types are also
  36    used while parsing an expression.
  37
  38    NOTE: This enumeration must match the op_rank array in expr.c.  */
  39
  40 typedef enum
  41 {
  42   /* An illegal expression.  */
  43   O_illegal,
  44   /* A nonexistent expression.  */
  45   O_absent,
  46   /* X_add_number (a constant expression).  */
  47   O_constant,
  48   /* X_add_symbol + X_add_number.  */
  49   O_symbol,
  50   /* X_add_symbol + X_add_number - the base address of the image.  */
  51   O_symbol_rva,
  52   /* The section index of X_add_symbol.  */
  53   O_secidx,
  54   /* A register (X_add_number is register number).  */
  55   O_register,
  56   /* A big value.  If X_add_number is negative or 0, the value is in
  57      generic_floating_point_number.  Otherwise the value is in
  58      generic_bignum, and X_add_number is the number of LITTLENUMs in
  59      the value.  */
  60   O_big,
  61   /* (- X_add_symbol) + X_add_number.  */
  62   O_uminus,
  63   /* (~ X_add_symbol) + X_add_number.  */
  64   O_bit_not,
  65   /* (! X_add_symbol) + X_add_number.  */
  66   O_logical_not,
  67   /* (X_add_symbol * X_op_symbol) + X_add_number.  */
  68   O_multiply,
  69   /* (X_add_symbol / X_op_symbol) + X_add_number.  */
  70   O_divide,
  71   /* (X_add_symbol % X_op_symbol) + X_add_number.  */
  72   O_modulus,
  73   /* (X_add_symbol << X_op_symbol) + X_add_number.  */
  74   O_left_shift,
  75   /* (X_add_symbol >> X_op_symbol) + X_add_number.  */
  76   O_right_shift,
  77   /* (X_add_symbol | X_op_symbol) + X_add_number.  */
  78   O_bit_inclusive_or,
  79   /* (X_add_symbol |~ X_op_symbol) + X_add_number.  */
  80   O_bit_or_not,
  81   /* (X_add_symbol ^ X_op_symbol) + X_add_number.  */
  82   O_bit_exclusive_or,
  83   /* (X_add_symbol & X_op_symbol) + X_add_number.  */
  84   O_bit_and,
  85   /* (X_add_symbol + X_op_symbol) + X_add_number.  */
  86   O_add,
  87   /* (X_add_symbol - X_op_symbol) + X_add_number.  */
  88   O_subtract,
  89   /* (X_add_symbol == X_op_symbol) + X_add_number.  */
  90   O_eq,
  91   /* (X_add_symbol != X_op_symbol) + X_add_number.  */
  92   O_ne,
  93   /* (X_add_symbol < X_op_symbol) + X_add_number.  */
  94   O_lt,
  95   /* (X_add_symbol <= X_op_symbol) + X_add_number.  */
  96   O_le,
  97   /* (X_add_symbol >= X_op_symbol) + X_add_number.  */
  98   O_ge,
  99   /* (X_add_symbol > X_op_symbol) + X_add_number.  */
 100   O_gt,
 101   /* (X_add_symbol && X_op_symbol) + X_add_number.  */
 102   O_logical_and,
 103   /* (X_add_symbol || X_op_symbol) + X_add_number.  */
 104   O_logical_or,
 105   /* X_op_symbol [ X_add_symbol ] */
 106   O_index,
 107   /* machine dependent operators */
 108   O_md1,  O_md2,  O_md3,  O_md4,  O_md5,  O_md6,  O_md7,  O_md8,
 109   O_md9,  O_md10, O_md11, O_md12, O_md13, O_md14, O_md15, O_md16,
 110   O_md17, O_md18, O_md19, O_md20, O_md21, O_md22, O_md23, O_md24,
 111   O_md25, O_md26, O_md27, O_md28, O_md29, O_md30, O_md31, O_md32,
 112   /* this must be the largest value */
 113   O_max
 114 } operatorT;
 115
 116 typedef struct expressionS
 117 {
 118   /* The main symbol.  */
 119   symbolS *X_add_symbol;
 120   /* The second symbol, if needed.  */
 121   symbolS *X_op_symbol;
 122   /* A number to add.  */
 123   offsetT X_add_number;
 124
 125   /* The type of the expression.  We can't assume that an arbitrary
 126      compiler can handle a bitfield of enum type.  FIXME: We could
 127      check this using autoconf.  */
 128 #ifdef __GNUC__
 129   operatorT X_op : 8;
 130 #else
 131   unsigned char X_op;
 132 #endif
 133
 134   /* Non-zero if X_add_number should be regarded as unsigned.  This is
 135      only valid for O_constant expressions.  It is only used when an
 136      O_constant must be extended into a bignum (i.e., it is not used
 137      when performing arithmetic on these values).
 138      FIXME: This field is not set very reliably.  */
 139   unsigned int X_unsigned : 1;
 140   /* This is used to implement "word size + 1 bit" arithmetic, so that e.g.
 141      expressions used with .sleb128 directives can use the full range available
 142      for an unsigned word, but can also properly represent all values of a
 143      signed word.  */
 144   unsigned int X_extrabit : 1;
 145
 146   /* 7 additional bits can be defined if needed.  */
 147
 148   /* Machine dependent field */
 149   unsigned short X_md;
 150 } expressionS;
 151
 152 enum expr_mode
 153 {
 154   expr_evaluate,
 155   expr_normal,
 156   expr_defer
 157 };
 158
 159 /* "result" should be type (expressionS *).  */
 160 #define expression(result) expr (0, result, expr_normal)
 161 #define expression_and_evaluate(result) expr (0, result, expr_evaluate)
 162 #define deferred_expression(result) expr (0, result, expr_defer)
 163
 164 /* If an expression is O_big, look here for its value. These common
 165    data may be clobbered whenever expr() is called.  */
 166 /* Flonums returned here.  Big enough to hold most precise flonum.  */
 167 extern FLONUM_TYPE generic_floating_point_number;
 168 /* Bignums returned here.  */
 169 extern LITTLENUM_TYPE generic_bignum[];
 170 /* Number of littlenums in above.  */
 171 #define SIZE_OF_LARGE_NUMBER (20)
 172
 173 typedef char operator_rankT;
 174
 175 extern char get_symbol_name (char **);
 176 extern char restore_line_pointer (char);
 177 extern void expr_begin (void);
 178 extern void expr_end (void);
 179 extern void expr_set_precedence (void);
 180 extern void expr_set_rank (operatorT, operator_rankT);
 181 extern void add_to_result (expressionS *, offsetT, int);
 182 extern void subtract_from_result (expressionS *, offsetT, int);
 183 extern segT expr (int, expressionS *, enum expr_mode);
 184 extern unsigned int get_single_number (void);
 185 extern symbolS *make_expr_symbol (expressionS * expressionP);
 186 extern int expr_symbol_where (symbolS *, const char **, unsigned int *);
 187 extern void current_location (expressionS *);
 188 extern symbolS *expr_build_uconstant (offsetT);
 189 extern symbolS *expr_build_dot (void);
 190 extern uint32_t generic_bignum_to_int32 (void);
 191 extern uint64_t generic_bignum_to_int64 (void);
 192 extern int resolve_expression (expressionS *);
 193
 194 extern bool literal_prefix_dollar_hex;