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   /* Return the opcode for the outermost sub-expression of this
  95      expression.  */
  96   enum exp_opcode first_opcode () const
  97   {
  98       return elts[0].opcode;
  99   }
 100
 101   /* Language it was entered in.  */
 102   const struct language_defn *language_defn;
 103   /* Architecture it was parsed in.  */
 104   struct gdbarch *gdbarch;
 105   int nelts = 0;
 106   union exp_element *elts;
 107 };
 108
 109 typedef std::unique_ptr<expression> expression_up;
 110
 111 /* Macros for converting between number of expression elements and bytes
 112    to store that many expression elements.  */
 113
 114 #define EXP_ELEM_TO_BYTES(elements) \
 115     ((elements) * sizeof (union exp_element))
 116 #define BYTES_TO_EXP_ELEM(bytes) \
 117     (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
 118
 119 /* From parse.c */
 120
 121 class innermost_block_tracker;
 122 extern expression_up parse_expression (const char *,
 123                                        innermost_block_tracker * = nullptr);
 124
 125 extern expression_up parse_expression_with_language (const char *string,
 126                                                      enum language lang);
 127
 128 extern struct type *parse_expression_for_completion
 129     (const char *, gdb::unique_xmalloc_ptr<char> *, enum type_code *);
 130
 131 class innermost_block_tracker;
 132 extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
 133                                   const struct block *, int,
 134                                   innermost_block_tracker * = nullptr);
 135
 136 /* From eval.c */
 137
 138 /* Values of NOSIDE argument to eval_subexp.  */
 139
 140 enum noside
 141   {
 142     EVAL_NORMAL,
 143     EVAL_SKIP,                  /* Only effect is to increment pos.
 144                                    Return type information where
 145                                    possible.  */
 146     EVAL_AVOID_SIDE_EFFECTS     /* Don't modify any variables or
 147                                    call any functions.  The value
 148                                    returned will have the correct
 149                                    type, and will have an
 150                                    approximately correct lvalue
 151                                    type (inaccuracy: anything that is
 152                                    listed as being in a register in
 153                                    the function in which it was
 154                                    declared will be lval_register).
 155                                    Ideally this would not even read
 156                                    target memory, but currently it
 157                                    does in many situations.  */
 158   };
 159
 160 extern struct value *evaluate_subexp_standard
 161   (struct type *, struct expression *, int *, enum noside);
 162
 163 /* Evaluate a function call.  The function to be called is in CALLEE and
 164    the arguments passed to the function are in ARGVEC.
 165    FUNCTION_NAME is the name of the function, if known.
 166    DEFAULT_RETURN_TYPE is used as the function's return type if the return
 167    type is unknown.  */
 168
 169 extern struct value *evaluate_subexp_do_call (expression *exp,
 170                                               enum noside noside,
 171                                               value *callee,
 172                                               gdb::array_view<value *> argvec,
 173                                               const char *function_name,
 174                                               type *default_return_type);
 175
 176 /* From expprint.c */
 177
 178 extern void print_expression (struct expression *, struct ui_file *);
 179
 180 extern const char *op_name (enum exp_opcode opcode);
 181
 182 extern const char *op_string (enum exp_opcode);
 183
 184 extern void dump_raw_expression (struct expression *,
 185                                  struct ui_file *, const char *);
 186 extern void dump_prefix_expression (struct expression *, struct ui_file *);
 187
 188 /* In an OP_RANGE expression, either bound could be empty, indicating
 189    that its value is by default that of the corresponding bound of the
 190    array or string.  Also, the upper end of the range can be exclusive
 191    or inclusive.  So we have six sorts of subrange.  This enumeration
 192    type is to identify this.  */
 193
 194 enum range_flag : unsigned
 195 {
 196   /* This is a standard range.  Both the lower and upper bounds are
 197      defined, and the bounds are inclusive.  */
 198   RANGE_STANDARD = 0,
 199
 200   /* The low bound was not given.  */
 201   RANGE_LOW_BOUND_DEFAULT = 1 << 0,
 202
 203   /* The high bound was not given.  */
 204   RANGE_HIGH_BOUND_DEFAULT = 1 << 1,
 205
 206   /* The high bound of this range is exclusive.  */
 207   RANGE_HIGH_BOUND_EXCLUSIVE = 1 << 2,
 208
 209   /* The range has a stride.  */
 210   RANGE_HAS_STRIDE = 1 << 3,
 211 };
 212
 213 DEF_ENUM_FLAGS_TYPE (enum range_flag, range_flags);
 214
 215 #endif /* !defined (EXPRESSION_H) */