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 #undef OP
  65
  66     /* Existing only to swallow the last comma (',') from last .inc file.  */
  67     OP_UNUSED_LAST
  68   };
  69
  70 union exp_element
  71   {
  72     enum exp_opcode opcode;
  73     struct symbol *symbol;
  74     struct minimal_symbol *msymbol;
  75     LONGEST longconst;
  76     gdb_byte floatconst[16];
  77     /* Really sizeof (union exp_element) characters (or less for the last
  78        element of a string).  */
  79     char string;
  80     struct type *type;
  81     struct internalvar *internalvar;
  82     const struct block *block;
  83     struct objfile *objfile;
  84   };
  85
  86 struct expression
  87 {
  88   expression (const struct language_defn *, struct gdbarch *, size_t);
  89   ~expression ();
  90   DISABLE_COPY_AND_ASSIGN (expression);
  91
  92   void resize (size_t);
  93
  94   /* Language it was entered in.  */
  95   const struct language_defn *language_defn;
  96   /* Architecture it was parsed in.  */
  97   struct gdbarch *gdbarch;
  98   int nelts = 0;
  99   union exp_element *elts;
 100 };
 101
 102 typedef std::unique_ptr<expression> expression_up;
 103
 104 /* Macros for converting between number of expression elements and bytes
 105    to store that many expression elements.  */
 106
 107 #define EXP_ELEM_TO_BYTES(elements) \
 108     ((elements) * sizeof (union exp_element))
 109 #define BYTES_TO_EXP_ELEM(bytes) \
 110     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 111
 112 /* From parse.c */
 113
 114 class innermost_block_tracker;
 115 extern expression_up parse_expression (const char *,
 116                                        innermost_block_tracker * = nullptr);
 117
 118 extern expression_up parse_expression_with_language (const char *string,
 119                                                      enum language lang);
 120
 121 extern struct type *parse_expression_for_completion
 122     (const char *, gdb::unique_xmalloc_ptr<char> *, enum type_code *);
 123
 124 class innermost_block_tracker;
 125 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 126                                   const struct block *, int,
 127                                   innermost_block_tracker * = nullptr);
 128
 129 /* From eval.c */
 130
 131 /* Values of NOSIDE argument to eval_subexp.  */
 132
 133 enum noside
 134   {
 135     EVAL_NORMAL,
 136     EVAL_SKIP,                  /* Only effect is to increment pos.
 137                                    Return type information where
 138                                    possible.  */
 139     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 140                                    call any functions.  The value
 141                                    returned will have the correct
 142                                    type, and will have an
 143                                    approximately correct lvalue
 144                                    type (inaccuracy: anything that is
 145                                    listed as being in a register in
 146                                    the function in which it was
 147                                    declared will be lval_register).
 148                                    Ideally this would not even read
 149                                    target memory, but currently it
 150                                    does in many situations.  */
 151   };
 152
 153 extern struct value *evaluate_subexp_standard
 154   (struct type *, struct expression *, int *, enum noside);
 155
 156 /* Evaluate a function call.  The function to be called is in CALLEE and
 157    the arguments passed to the function are in ARGVEC.
 158    FUNCTION_NAME is the name of the function, if known.
 159    DEFAULT_RETURN_TYPE is used as the function's return type if the return
 160    type is unknown.  */
 161
 162 extern struct value *evaluate_subexp_do_call (expression *exp,
 163                                               enum noside noside,
 164                                               value *callee,
 165                                               gdb::array_view<value *> argvec,
 166                                               const char *function_name,
 167                                               type *default_return_type);
 168
 169 /* From expprint.c */
 170
 171 extern void print_expression (struct expression *, struct ui_file *);
 172
 173 extern const char *op_name (enum exp_opcode opcode);
 174
 175 extern const char *op_string (enum exp_opcode);
 176
 177 extern void dump_raw_expression (struct expression *,
 178                                  struct ui_file *, const char *);
 179 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 180
 181 /* In an OP_RANGE expression, either bound could be empty, indicating
 182    that its value is by default that of the corresponding bound of the
 183    array or string.  Also, the upper end of the range can be exclusive
 184    or inclusive.  So we have six sorts of subrange.  This enumeration
 185    type is to identify this.  */
 186
 187 enum range_flag : unsigned
 188 {
 189   /* This is a standard range.  Both the lower and upper bounds are
 190      defined, and the bounds are inclusive.  */
 191   RANGE_STANDARD = 0,
 192
 193   /* The low bound was not given.  */
 194   RANGE_LOW_BOUND_DEFAULT = 1 << 0,
 195
 196   /* The high bound was not given.  */
 197   RANGE_HIGH_BOUND_DEFAULT = 1 << 1,
 198
 199   /* The high bound of this range is exclusive.  */
 200   RANGE_HIGH_BOUND_EXCLUSIVE = 1 << 2,
 201
 202   /* The range has a stride.  */
 203   RANGE_HAS_STRIDE = 1 << 3,
 204 };
 205
 206 DEF_ENUM_FLAGS_TYPE (enum range_flag, range_flags);
 207
 208 #endif /* !defined (EXPRESSION_H) */