path: root/gdb/value.h

/* Definitions for values of C expressions, for GDB.

   Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
   2008, 2009, 2010 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#if !defined (VALUE_H)
#define VALUE_H 1

#include "doublest.h"
#include "frame.h"		/* For struct frame_id.  */

struct block;
struct expression;
struct regcache;
struct symbol;
struct type;
struct ui_file;
struct language_defn;
struct value_print_options;

/* The structure which defines the type of a value.  It should never
   be possible for a program lval value to survive over a call to the
   inferior (i.e. to be put into the history list or an internal
   variable).  */

struct value;

/* Values are stored in a chain, so that they can be deleted easily
   over calls to the inferior.  Values assigned to internal variables,
   put into the value history or exposed to Python are taken off this
   list.  */

struct value *value_next (struct value *);

/* Type of the value.  */

extern struct type *value_type (struct value *);

/* This is being used to change the type of an existing value, that
   code should instead be creating a new value with the changed type
   (but possibly shared content).  */

extern void deprecated_set_value_type (struct value *value,
				       struct type *type);

/* Only used for bitfields; number of bits contained in them.  */

extern int value_bitsize (struct value *);
extern void set_value_bitsize (struct value *, int bit);

/* Only used for bitfields; position of start of field.  For
   gdbarch_bits_big_endian=0 targets, it is the position of the LSB.  For
   gdbarch_bits_big_endian=1 targets, it is the position of the MSB.  */

extern int value_bitpos (struct value *);
extern void set_value_bitpos (struct value *, int bit);

/* Only used for bitfields; the containing value.  This allows a
   single read from the target when displaying multiple
   bitfields.  */

struct value *value_parent (struct value *);

/* Describes offset of a value within lval of a structure in bytes.
   If lval == lval_memory, this is an offset to the address.  If lval
   == lval_register, this is a further offset from location.address
   within the registers structure.  Note also the member
   embedded_offset below.  */

extern int value_offset (struct value *);
extern void set_value_offset (struct value *, int offset);

/* The comment from "struct value" reads: ``Is it modifiable?  Only
   relevant if lval != not_lval.''.  Shouldn't the value instead be
   not_lval and be done with it?  */

extern int deprecated_value_modifiable (struct value *value);
extern void deprecated_set_value_modifiable (struct value *value,
					     int modifiable);

/* If a value represents a C++ object, then the `type' field gives the
   object's compile-time type.  If the object actually belongs to some
   class derived from `type', perhaps with other base classes and
   additional members, then `type' is just a subobject of the real
   thing, and the full object is probably larger than `type' would
   suggest.

   If `type' is a dynamic class (i.e. one with a vtable), then GDB can
   actually determine the object's run-time type by looking at the
   run-time type information in the vtable.  When this information is
   available, we may elect to read in the entire object, for several
   reasons:

   - When printing the value, the user would probably rather see the
     full object, not just the limited portion apparent from the
     compile-time type.

   - If `type' has virtual base classes, then even printing `type'
     alone may require reaching outside the `type' portion of the
     object to wherever the virtual base class has been stored.

   When we store the entire object, `enclosing_type' is the run-time
   type -- the complete object -- and `embedded_offset' is the offset
   of `type' within that larger type, in bytes.  The value_contents()
   macro takes `embedded_offset' into account, so most GDB code
   continues to see the `type' portion of the value, just as the
   inferior would.

   If `type' is a pointer to an object, then `enclosing_type' is a
   pointer to the object's run-time type, and `pointed_to_offset' is
   the offset in bytes from the full object to the pointed-to object
   -- that is, the value `embedded_offset' would have if we followed
   the pointer and fetched the complete object.  (I don't really see
   the point.  Why not just determine the run-time type when you
   indirect, and avoid the special case?  The contents don't matter
   until you indirect anyway.)

   If we're not doing anything fancy, `enclosing_type' is equal to
   `type', and `embedded_offset' is zero, so everything works
   normally.  */

extern struct type *value_enclosing_type (struct value *);
extern struct value *value_change_enclosing_type (struct value *val,
						  struct type *new_type);
extern int value_pointed_to_offset (struct value *value);
extern void set_value_pointed_to_offset (struct value *value, int val);
extern int value_embedded_offset (struct value *value);
extern void set_value_embedded_offset (struct value *value, int val);

/* For lval_computed values, this structure holds functions used to
   retrieve and set the value (or portions of the value).

   For each function, 'V' is the 'this' pointer: an lval_funcs
   function F may always assume that the V it receives is an
   lval_computed value, and has F in the appropriate slot of its
   lval_funcs structure.  */

struct lval_funcs
{
  /* Fill in VALUE's contents.  This is used to "un-lazy" values.  If
     a problem arises in obtaining VALUE's bits, this function should
     call 'error'.  */
  void (*read) (struct value *v);

  /* Handle an assignment TOVAL = FROMVAL by writing the value of
     FROMVAL to TOVAL's location.  The contents of TOVAL have not yet
     been updated.  If a problem arises in doing so, this function
     should call 'error'.  */
  void (*write) (struct value *toval, struct value *fromval);

  /* Return a duplicate of VALUE's closure, for use in a new value.
     This may simply return the same closure, if VALUE's is
     reference-counted or statically allocated.

     This may be NULL, in which case VALUE's closure is re-used in the
     new value.  */
  void *(*copy_closure) (struct value *v);

  /* Drop VALUE's reference to its closure.  Maybe this frees the
     closure; maybe this decrements a reference count; maybe the
     closure is statically allocated and this does nothing.

     This may be NULL, in which case no action is taken to free
     VALUE's closure.  */
  void (*free_closure) (struct value *v);
};

/* Create a computed lvalue, with type TYPE, function pointers FUNCS,
   and closure CLOSURE.  */

extern struct value *allocate_computed_value (struct type *type,
                                              struct lval_funcs *funcs,
                                              void *closure);

/* If VALUE is lval_computed, return its lval_funcs structure.  */

extern struct lval_funcs *value_computed_funcs (struct value *value);

/* If VALUE is lval_computed, return its closure.  The meaning of the
   returned value depends on the functions VALUE uses.  */

extern void *value_computed_closure (struct value *value);

/* If zero, contents of this value are in the contents field.  If
   nonzero, contents are in inferior.  If the lval field is lval_memory,
   the contents are in inferior memory at location.address plus offset.
   The lval field may also be lval_register.

   WARNING: This field is used by the code which handles watchpoints
   (see breakpoint.c) to decide whether a particular value can be
   watched by hardware watchpoints.  If the lazy flag is set for some
   member of a value chain, it is assumed that this member of the
   chain doesn't need to be watched as part of watching the value
   itself.  This is how GDB avoids watching the entire struct or array
   when the user wants to watch a single struct member or array
   element.  If you ever change the way lazy flag is set and reset, be
   sure to consider this use as well!  */

extern int value_lazy (struct value *);
extern void set_value_lazy (struct value *value, int val);

extern int value_stack (struct value *);
extern void set_value_stack (struct value *value, int val);

/* value_contents() and value_contents_raw() both return the address
   of the gdb buffer used to hold a copy of the contents of the lval.
   value_contents() is used when the contents of the buffer are needed
   -- it uses value_fetch_lazy() to load the buffer from the process
   being debugged if it hasn't already been loaded
   (value_contents_writeable() is used when a writeable but fetched
   buffer is required)..  value_contents_raw() is used when data is
   being stored into the buffer, or when it is certain that the
   contents of the buffer are valid.

   Note: The contents pointer is adjusted by the offset required to
   get to the real subobject, if the value happens to represent
   something embedded in a larger run-time object.  */

extern gdb_byte *value_contents_raw (struct value *);

/* Actual contents of the value.  For use of this value; setting it
   uses the stuff above.  Not valid if lazy is nonzero.  Target
   byte-order.  We force it to be aligned properly for any possible
   value.  Note that a value therefore extends beyond what is
   declared here.  */

extern const gdb_byte *value_contents (struct value *);
extern gdb_byte *value_contents_writeable (struct value *);

/* The ALL variants of the above two macros do not adjust the returned
   pointer by the embedded_offset value.  */

extern gdb_byte *value_contents_all_raw (struct value *);
extern const gdb_byte *value_contents_all (struct value *);

extern int value_fetch_lazy (struct value *val);
extern int value_contents_equal (struct value *val1, struct value *val2);

/* If nonzero, this is the value of a variable which does not actually
   exist in the program.  */
extern int value_optimized_out (struct value *value);
extern void set_value_optimized_out (struct value *value, int val);

/* Set or return field indicating whether a variable is initialized or
   not, based on debugging information supplied by the compiler. 
   1 = initialized; 0 = uninitialized.  */
extern int value_initialized (struct value *);
extern void set_value_initialized (struct value *, int);

/* Set COMPONENT's location as appropriate for a component of WHOLE
   --- regardless of what kind of lvalue WHOLE is.  */
extern void set_value_component_location (struct value *component,
                                          struct value *whole);

/* While the following fields are per- VALUE .CONTENT .PIECE (i.e., a
   single value might have multiple LVALs), this hacked interface is
   limited to just the first PIECE.  Expect further change.  */
/* Type of value; either not an lval, or one of the various different
   possible kinds of lval.  */
extern enum lval_type *deprecated_value_lval_hack (struct value *);
#define VALUE_LVAL(val) (*deprecated_value_lval_hack (val))

/* If lval == lval_memory, return the address in the inferior.  If
   lval == lval_register, return the byte offset into the registers
   structure.  Otherwise, return 0.  The returned address
   includes the offset, if any.  */
extern CORE_ADDR value_address (struct value *);

/* Like value_address, except the result does not include value's
   offset.  */
extern CORE_ADDR value_raw_address (struct value *);

/* Set the address of a value.  */
extern void set_value_address (struct value *, CORE_ADDR);

/* Pointer to internal variable.  */
extern struct internalvar **deprecated_value_internalvar_hack (struct value *);
#define VALUE_INTERNALVAR(val) (*deprecated_value_internalvar_hack (val))

/* Frame register value is relative to.  This will be described in the
   lval enum above as "lval_register".  */
extern struct frame_id *deprecated_value_frame_id_hack (struct value *);
#define VALUE_FRAME_ID(val) (*deprecated_value_frame_id_hack (val))

/* Register number if the value is from a register.  */
extern short *deprecated_value_regnum_hack (struct value *);
#define VALUE_REGNUM(val) (*deprecated_value_regnum_hack (val))

/* Convert a REF to the object referenced.  */

extern struct value *coerce_ref (struct value *value);

/* If ARG is an array, convert it to a pointer.
   If ARG is a function, convert it to a function pointer.

   References are dereferenced.  */

extern struct value *coerce_array (struct value *value);



#include "symtab.h"
#include "gdbtypes.h"
#include "expression.h"

struct frame_info;
struct fn_field;

extern void print_address_demangle (struct gdbarch *, CORE_ADDR,
				    struct ui_file *, int);

extern LONGEST value_as_long (struct value *val);
extern DOUBLEST value_as_double (struct value *val);
extern CORE_ADDR value_as_address (struct value *val);

extern LONGEST unpack_long (struct type *type, const gdb_byte *valaddr);
extern DOUBLEST unpack_double (struct type *type, const gdb_byte *valaddr,
			       int *invp);
extern CORE_ADDR unpack_pointer (struct type *type, const gdb_byte *valaddr);
LONGEST unpack_bits_as_long (struct type *field_type, const gdb_byte *valaddr,
			     int bitpos, int bitsize);
extern LONGEST unpack_field_as_long (struct type *type,
				     const gdb_byte *valaddr,
				     int fieldno);

extern void pack_long (gdb_byte *buf, struct type *type, LONGEST num);

extern struct value *value_from_longest (struct type *type, LONGEST num);
extern struct value *value_from_pointer (struct type *type, CORE_ADDR addr);
extern struct value *value_from_double (struct type *type, DOUBLEST num);
extern struct value *value_from_decfloat (struct type *type,
					  const gdb_byte *decbytes);

extern struct value *value_at (struct type *type, CORE_ADDR addr);
extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr);

extern struct value *value_from_contents_and_address (struct type *,
						      const gdb_byte *,
						      CORE_ADDR);

extern struct value *default_value_from_register (struct type *type,
						  int regnum,
						  struct frame_info *frame);

extern struct value *value_from_register (struct type *type, int regnum,
					  struct frame_info *frame);

extern CORE_ADDR address_from_register (struct type *type, int regnum,
					struct frame_info *frame);

extern struct value *value_of_variable (struct symbol *var, struct block *b);

extern struct value *address_of_variable (struct symbol *var, struct block *b);

extern struct value *value_of_register (int regnum, struct frame_info *frame);

struct value *value_of_register_lazy (struct frame_info *frame, int regnum);

extern int symbol_read_needs_frame (struct symbol *);

extern struct value *read_var_value (struct symbol *var,
				     struct frame_info *frame);

extern struct value *allocate_value (struct type *type);
extern struct value *allocate_value_lazy (struct type *type);
extern void allocate_value_contents (struct value *value);

extern struct value *allocate_repeat_value (struct type *type, int count);

extern struct value *value_mark (void);

extern void value_free_to_mark (struct value *mark);

extern struct value *value_cstring (char *ptr, int len,
				    struct type *char_type);
extern struct value *value_string (char *ptr, int len,
				   struct type *char_type);
extern struct value *value_bitstring (char *ptr, int len,
				      struct type *index_type);

extern struct value *value_array (int lowbound, int highbound,
				  struct value **elemvec);

extern struct value *value_concat (struct value *arg1, struct value *arg2);

extern struct value *value_binop (struct value *arg1, struct value *arg2,
				  enum exp_opcode op);

extern struct value *value_ptradd (struct value *arg1, LONGEST arg2);

extern LONGEST value_ptrdiff (struct value *arg1, struct value *arg2);

extern int value_must_coerce_to_target (struct value *arg1);

extern struct value *value_coerce_to_target (struct value *arg1);

extern struct value *value_coerce_array (struct value *arg1);

extern struct value *value_coerce_function (struct value *arg1);

extern struct value *value_ind (struct value *arg1);

extern struct value *value_addr (struct value *arg1);

extern struct value *value_ref (struct value *arg1);

extern struct value *value_assign (struct value *toval,
				   struct value *fromval);

extern struct value *value_pos (struct value *arg1);

extern struct value *value_neg (struct value *arg1);

extern struct value *value_complement (struct value *arg1);

extern struct value *value_struct_elt (struct value **argp,
				       struct value **args,
				       const char *name, int *static_memfuncp,
				       const char *err);

extern struct value *value_aggregate_elt (struct type *curtype,
					  char *name,
					  struct type *expect_type,
					  int want_address,
					  enum noside noside);

extern struct value *value_static_field (struct type *type, int fieldno);

extern struct fn_field *value_find_oload_method_list (struct value **,
						      const char *,
						      int, int *,
						      struct type **, int *);

extern int find_overload_match (struct type **arg_types, int nargs,
				const char *name, int method, int lax,
				struct value **objp, struct symbol *fsym,
				struct value **valp, struct symbol **symp,
				int *staticp);

extern struct value *value_field (struct value *arg1, int fieldno);

extern struct value *value_primitive_field (struct value *arg1, int offset,
					    int fieldno,
					    struct type *arg_type);


extern struct type *value_rtti_target_type (struct value *, int *, int *,
					    int *);

extern struct value *value_full_object (struct value *, struct type *, int,
					int, int);

extern struct value *value_cast_pointers (struct type *, struct value *);

extern struct value *value_cast (struct type *type, struct value *arg2);

extern struct value *value_reinterpret_cast (struct type *type,
					     struct value *arg);

extern struct value *value_dynamic_cast (struct type *type, struct value *arg);

extern struct value *value_zero (struct type *type, enum lval_type lv);

extern struct value *value_one (struct type *type, enum lval_type lv);

extern struct value *value_repeat (struct value *arg1, int count);

extern struct value *value_subscript (struct value *array, LONGEST index);

extern struct value *value_bitstring_subscript (struct type *type,
						struct value *bitstring,
						LONGEST index);

extern struct value *register_value_being_returned (struct type *valtype,
						    struct regcache *retbuf);

extern int value_in (struct value *element, struct value *set);

extern int value_bit_index (struct type *type, const gdb_byte *addr,
			    int index);

extern int using_struct_return (struct gdbarch *gdbarch,
				struct type *func_type,
				struct type *value_type);

extern struct value *evaluate_expression (struct expression *exp);

extern struct value *evaluate_type (struct expression *exp);

extern struct value *evaluate_subexp (struct type *expect_type,
				      struct expression *exp,
				      int *pos, enum noside noside);

extern struct value *evaluate_subexpression_type (struct expression *exp,
						  int subexp);

extern char *extract_field_op (struct expression *exp, int *subexp);

extern struct value *evaluate_subexp_with_coercion (struct expression *,
						    int *, enum noside);

extern struct value *parse_and_eval (char *exp);

extern struct value *parse_to_comma_and_eval (char **expp);

extern struct type *parse_and_eval_type (char *p, int length);

extern CORE_ADDR parse_and_eval_address (char *exp);

extern CORE_ADDR parse_and_eval_address_1 (char **expptr);

extern LONGEST parse_and_eval_long (char *exp);

extern void unop_promote (const struct language_defn *language,
			  struct gdbarch *gdbarch,
			  struct value **arg1);

extern void binop_promote (const struct language_defn *language,
			   struct gdbarch *gdbarch,
			   struct value **arg1, struct value **arg2);

extern struct value *access_value_history (int num);

extern struct value *value_of_internalvar (struct gdbarch *gdbarch,
					   struct internalvar *var);

extern int get_internalvar_integer (struct internalvar *var, LONGEST *l);

extern void set_internalvar (struct internalvar *var, struct value *val);

extern void set_internalvar_integer (struct internalvar *var, LONGEST l);

extern void set_internalvar_string (struct internalvar *var,
				    const char *string);

extern void clear_internalvar (struct internalvar *var);

extern void set_internalvar_component (struct internalvar *var,
				       int offset,
				       int bitpos, int bitsize,
				       struct value *newvalue);

extern struct internalvar *lookup_only_internalvar (const char *name);

extern struct internalvar *create_internalvar (const char *name);

typedef struct value * (*internalvar_make_value) (struct gdbarch *,
						  struct internalvar *);
extern struct internalvar *
  create_internalvar_type_lazy (char *name, internalvar_make_value fun);

extern struct internalvar *lookup_internalvar (const char *name);

extern int value_equal (struct value *arg1, struct value *arg2);

extern int value_equal_contents (struct value *arg1, struct value *arg2);

extern int value_less (struct value *arg1, struct value *arg2);

extern int value_logical_not (struct value *arg1);

/* C++ */

extern struct value *value_of_this (int complain);

extern struct value *value_x_binop (struct value *arg1, struct value *arg2,
				    enum exp_opcode op,
				    enum exp_opcode otherop,
				    enum noside noside);

extern struct value *value_x_unop (struct value *arg1, enum exp_opcode op,
				   enum noside noside);

extern struct value *value_fn_field (struct value **arg1p, struct fn_field *f,
				     int j, struct type *type, int offset);

extern int binop_user_defined_p (enum exp_opcode op, struct value *arg1,
				 struct value *arg2);

extern int unop_user_defined_p (enum exp_opcode op, struct value *arg1);

extern int destructor_name_p (const char *name, const struct type *type);

extern void value_incref (struct value *val);

extern void value_free (struct value *val);

extern void free_all_values (void);

extern void release_value (struct value *val);

extern int record_latest_value (struct value *val);

extern void modify_field (struct type *type, gdb_byte *addr,
			  LONGEST fieldval, int bitpos, int bitsize);

extern void type_print (struct type *type, char *varstring,
			struct ui_file *stream, int show);

extern char *type_to_string (struct type *type);

extern gdb_byte *baseclass_addr (struct type *type, int index,
				 gdb_byte *valaddr,
				 struct value **valuep, int *errp);

extern void print_longest (struct ui_file *stream, int format,
			   int use_local, LONGEST val);

extern void print_floating (const gdb_byte *valaddr, struct type *type,
			    struct ui_file *stream);

extern void print_decimal_floating (const gdb_byte *valaddr, struct type *type,
				    struct ui_file *stream);

extern int value_print (struct value *val, struct ui_file *stream,
			const struct value_print_options *options);

extern void value_print_array_elements (struct value *val,
					struct ui_file *stream, int format,
					enum val_prettyprint pretty);

extern struct value *value_release_to_mark (struct value *mark);

extern int val_print (struct type *type, const gdb_byte *valaddr,
		      int embedded_offset, CORE_ADDR address,
		      struct ui_file *stream, int recurse,
		      const struct value_print_options *options,
		      const struct language_defn *language);

extern int common_val_print (struct value *val,
			     struct ui_file *stream, int recurse,
			     const struct value_print_options *options,
			     const struct language_defn *language);

extern int val_print_string (struct type *elttype, CORE_ADDR addr, int len,
			     struct ui_file *stream,
			     const struct value_print_options *options);

extern void print_variable_and_value (const char *name,
				      struct symbol *var,
				      struct frame_info *frame,
				      struct ui_file *stream,
				      int indent);

extern int check_field (struct type *, const char *);

extern void typedef_print (struct type *type, struct symbol *news,
			   struct ui_file *stream);

extern char *internalvar_name (struct internalvar *var);

extern void preserve_values (struct objfile *);

/* From values.c */

extern struct value *value_copy (struct value *);

extern void preserve_one_value (struct value *, struct objfile *, htab_t);

/* From valops.c */

extern struct value *varying_to_slice (struct value *);

extern struct value *value_slice (struct value *, int, int);

extern struct value *value_literal_complex (struct value *, struct value *,
					    struct type *);

extern struct value *find_function_in_inferior (const char *,
						struct objfile **);

extern struct value *value_allocate_space_in_inferior (int);

extern struct value *value_of_local (const char *name, int complain);

extern struct value *value_subscripted_rvalue (struct value *array,
					       LONGEST index, int lowerbound);

/* User function handler.  */

typedef struct value *(*internal_function_fn) (struct gdbarch *gdbarch,
					       const struct language_defn *language,
					       void *cookie,
					       int argc,
					       struct value **argv);

void add_internal_function (const char *name, const char *doc,
			    internal_function_fn handler,
			    void *cookie);

struct value *call_internal_function (struct gdbarch *gdbarch,
				      const struct language_defn *language,
				      struct value *function,
				      int argc, struct value **argv);

char *value_internal_function_name (struct value *);

#endif /* !defined (VALUE_H) */