xref: /freebsd-10.1-release/contrib/gdb/gdb/dwarf2expr.h

/* Dwarf2 Expression Evaluator
   Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
   Contributed by Daniel Berlin (dan@dberlin.org)
   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 2 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, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#if !defined (DWARF2EXPR_H)
#define DWARF2EXPR_H

/* The expression evaluator works with a dwarf_expr_context, describing
   its current state and its callbacks.  */
struct dwarf_expr_context
{
  /* The stack of values, allocated with xmalloc.  */
  CORE_ADDR *stack;

  /* The number of values currently pushed on the stack, and the
     number of elements allocated to the stack.  */
  int stack_len, stack_allocated;

  /* An opaque argument provided by the caller, which will be passed
     to all of the callback functions.  */
  void *baton;

  /* Return the value of register number REGNUM.  */
  CORE_ADDR (*read_reg) (void *baton, int regnum);

  /* Read LENGTH bytes at ADDR into BUF.  */
  void (*read_mem) (void *baton, char *buf, CORE_ADDR addr,
		    size_t length);

  /* Return the location expression for the frame base attribute, in
     START and LENGTH.  The result must be live until the current
     expression evaluation is complete.  */
  void (*get_frame_base) (void *baton, unsigned char **start,
			 size_t *length);

  /* Return the thread-local storage address for
     DW_OP_GNU_push_tls_address.  */
  CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset);

#if 0
  /* Not yet implemented.  */

  /* Return the location expression for the dwarf expression
     subroutine in the die at OFFSET in the current compilation unit.
     The result must be live until the current expression evaluation
     is complete.  */
  unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length);

  /* Return the `object address' for DW_OP_push_object_address.  */
  CORE_ADDR (*get_object_address) (void *baton);
#endif

  /* The current depth of dwarf expression recursion, via DW_OP_call*,
     DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
     depth we'll tolerate before raising an error.  */
  int recursion_depth, max_recursion_depth;

  /* Non-zero if the result is in a register.  The register number
     will be on the expression stack.  */
  int in_reg;
};

struct dwarf_expr_context *new_dwarf_expr_context (void);
void free_dwarf_expr_context (struct dwarf_expr_context *ctx);

void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value);
void dwarf_expr_pop (struct dwarf_expr_context *ctx);
void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr,
		      size_t len);
CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);


unsigned char *read_uleb128 (unsigned char *buf, unsigned char *buf_end,
			     ULONGEST * r);
unsigned char *read_sleb128 (unsigned char *buf, unsigned char *buf_end,
			     LONGEST * r);
CORE_ADDR dwarf2_read_address (unsigned char *buf, unsigned char *buf_end,
			       int *bytes_read);

#endif