gdb/expression.h

   1 /* Definitions for expressions stored in reversed prefix form, for GDB.
   2
   3    Copyright (C) 1986-2020 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #if !defined (EXPRESSION_H)
  21 #define EXPRESSION_H 1
  22
  23 #include "gdbtypes.h"
  24
  25 /* While parsing expressions we need to track the innermost lexical block
  26    that we encounter.  In some situations we need to track the innermost
  27    block just for symbols, and in other situations we want to track the
  28    innermost block for symbols and registers.  These flags are used by the
  29    innermost block tracker to control which blocks we consider for the
  30    innermost block.  These flags can be combined together as needed.  */
  31
  32 enum innermost_block_tracker_type
  33 {
  34   /* Track the innermost block for symbols within an expression.  */
  35   INNERMOST_BLOCK_FOR_SYMBOLS = (1 << 0),
  36
  37   /* Track the innermost block for registers within an expression.  */
  38   INNERMOST_BLOCK_FOR_REGISTERS = (1 << 1)
  39 };
  40 DEF_ENUM_FLAGS_TYPE (enum innermost_block_tracker_type,
  41                      innermost_block_tracker_types);
  42
  43 /* Definitions for saved C expressions.  */
  44
  45 /* An expression is represented as a vector of union exp_element's.
  46    Each exp_element is an opcode, except that some opcodes cause
  47    the following exp_element to be treated as a long or double constant
  48    or as a variable.  The opcodes are obeyed, using a stack for temporaries.
  49    The value is left on the temporary stack at the end.  */
  50
  51 /* When it is necessary to include a string,
  52    it can occupy as many exp_elements as it needs.
  53    We find the length of the string using strlen,
  54    divide to find out how many exp_elements are used up,
  55    and skip that many.  Strings, like numbers, are indicated
  56    by the preceding opcode.  */
  57
  58 enum exp_opcode : uint8_t
  59   {
  60 #define OP(name) name ,
  61
  62 #include "std-operator.def"
  63
  64     /* First extension operator.  Individual language modules define extra
  65        operators in *.def include files below with numbers higher than
  66        OP_EXTENDED0.  */
  67     OP (OP_EXTENDED0)
  68
  69 /* Language specific operators.  */
  70 #include "ada-operator.def"
  71 #include "fortran-operator.def"
  72
  73 #undef OP
  74
  75     /* Existing only to swallow the last comma (',') from last .inc file.  */
  76     OP_UNUSED_LAST
  77   };
  78
  79 union exp_element
  80   {
  81     enum exp_opcode opcode;
  82     struct symbol *symbol;
  83     struct minimal_symbol *msymbol;
  84     LONGEST longconst;
  85     gdb_byte floatconst[16];
  86     /* Really sizeof (union exp_element) characters (or less for the last
  87        element of a string).  */
  88     char string;
  89     struct type *type;
  90     struct internalvar *internalvar;
  91     const struct block *block;
  92     struct objfile *objfile;
  93   };
  94
  95 struct expression
  96 {
  97   expression (const struct language_defn *, struct gdbarch *, size_t);
  98   ~expression ();
  99   DISABLE_COPY_AND_ASSIGN (expression);
 100
 101   void resize (size_t);
 102
 103   /* Language it was entered in.  */
 104   const struct language_defn *language_defn;
 105   /* Architecture it was parsed in.  */
 106   struct gdbarch *gdbarch;
 107   int nelts = 0;
 108   union exp_element *elts;
 109 };
 110
 111 typedef std::unique_ptr<expression> expression_up;
 112
 113 /* Macros for converting between number of expression elements and bytes
 114    to store that many expression elements.  */
 115
 116 #define EXP_ELEM_TO_BYTES(elements) \
 117     ((elements) * sizeof (union exp_element))
 118 #define BYTES_TO_EXP_ELEM(bytes) \
 119     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 120
 121 /* From parse.c */
 122
 123 class innermost_block_tracker;
 124 extern expression_up parse_expression (const char *,
 125                                        innermost_block_tracker * = nullptr);
 126
 127 extern expression_up parse_expression_with_language (const char *string,
 128                                                      enum language lang);
 129
 130 extern struct type *parse_expression_for_completion
 131     (const char *, gdb::unique_xmalloc_ptr<char> *, enum type_code *);
 132
 133 class innermost_block_tracker;
 134 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 135                                   const struct block *, int,
 136                                   innermost_block_tracker * = nullptr);
 137
 138 /* From eval.c */
 139
 140 /* Values of NOSIDE argument to eval_subexp.  */
 141
 142 enum noside
 143   {
 144     EVAL_NORMAL,
 145     EVAL_SKIP,                  /* Only effect is to increment pos.
 146                                    Return type information where
 147                                    possible.  */
 148     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 149                                    call any functions.  The value
 150                                    returned will have the correct
 151                                    type, and will have an
 152                                    approximately correct lvalue
 153                                    type (inaccuracy: anything that is
 154                                    listed as being in a register in
 155                                    the function in which it was
 156                                    declared will be lval_register).
 157                                    Ideally this would not even read
 158                                    target memory, but currently it
 159                                    does in many situations.  */
 160   };
 161
 162 extern struct value *evaluate_subexp_standard
 163   (struct type *, struct expression *, int *, enum noside);
 164
 165 /* Evaluate a function call.  The function to be called is in ARGVEC[0] and
 166    the arguments passed to the function are in ARGVEC[1..NARGS].
 167    FUNCTION_NAME is the name of the function, if known.
 168    DEFAULT_RETURN_TYPE is used as the function's return type if the return
 169    type is unknown.  */
 170
 171 extern struct value *evaluate_subexp_do_call (expression *exp,
 172                                               enum noside noside,
 173                                               int nargs, value **argvec,
 174                                               const char *function_name,
 175                                               type *default_return_type);
 176
 177 /* From expprint.c */
 178
 179 extern void print_expression (struct expression *, struct ui_file *);
 180
 181 extern const char *op_name (enum exp_opcode opcode);
 182
 183 extern const char *op_string (enum exp_opcode);
 184
 185 extern void dump_raw_expression (struct expression *,
 186                                  struct ui_file *, const char *);
 187 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 188
 189 /* In an OP_RANGE expression, either bound could be empty, indicating
 190    that its value is by default that of the corresponding bound of the
 191    array or string.  Also, the upper end of the range can be exclusive
 192    or inclusive.  So we have six sorts of subrange.  This enumeration
 193    type is to identify this.  */
 194
 195 enum range_flag : unsigned
 196 {
 197   /* This is a standard range.  Both the lower and upper bounds are
 198      defined, and the bounds are inclusive.  */
 199   RANGE_STANDARD = 0,
 200
 201   /* The low bound was not given.  */
 202   RANGE_LOW_BOUND_DEFAULT = 1 << 0,
 203
 204   /* The high bound was not given.  */
 205   RANGE_HIGH_BOUND_DEFAULT = 1 << 1,
 206
 207   /* The high bound of this range is exclusive.  */
 208   RANGE_HIGH_BOUND_EXCLUSIVE = 1 << 2,
 209
 210   /* The range has a stride.  */
 211   RANGE_HAS_STRIDE = 1 << 3,
 212 };
 213
 214 DEF_ENUM_FLAGS_TYPE (enum range_flag, range_flags);
 215
 216 #endif /* !defined (EXPRESSION_H) */