gas/expr.h

   1 /* expr.h -> header file for expr.c
   2    Copyright (C) 1987-2015 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_end (void);
 174 extern void expr_begin (void);
 175 extern void expr_set_precedence (void);
 176 extern void expr_set_rank (operatorT, operator_rankT);
 177 extern void add_to_result (expressionS *, offsetT, int);
 178 extern void subtract_from_result (expressionS *, offsetT, int);
 179 extern segT expr (int, expressionS *, enum expr_mode);
 180 extern unsigned int get_single_number (void);
 181 extern symbolS *make_expr_symbol (expressionS * expressionP);
 182 extern int expr_symbol_where (symbolS *, char **, unsigned int *);
 183 extern void current_location (expressionS *);
 184
 185 extern symbolS *expr_build_uconstant (offsetT);
 186 extern symbolS *expr_build_dot (void);
 187
 188 int resolve_expression (expressionS *);