[deliverable/binutils-gdb.git] / gdb / dwarf2expr.h

/* DWARF 2 Expression Evaluator.

   Copyright (C) 2001-2017 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 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 (DWARF2EXPR_H)
#define DWARF2EXPR_H

#include "leb128.h"
#include "gdbtypes.h"

/* The location of a value.  */
enum dwarf_value_location
{
  /* The piece is in memory.
     The value on the dwarf stack is its address.  */
  DWARF_VALUE_MEMORY,

  /* The piece is in a register.
     The value on the dwarf stack is the register number.  */
  DWARF_VALUE_REGISTER,

  /* The piece is on the dwarf stack.  */
  DWARF_VALUE_STACK,

  /* The piece is a literal.  */
  DWARF_VALUE_LITERAL,

  /* The piece was optimized out.  */
  DWARF_VALUE_OPTIMIZED_OUT,

  /* The piece is an implicit pointer.  */
  DWARF_VALUE_IMPLICIT_POINTER
};

/* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece.  */
struct dwarf_expr_piece
{
  enum dwarf_value_location location;

  union
  {
    struct
    {
      /* This piece's address, for DWARF_VALUE_MEMORY pieces.  */
      CORE_ADDR addr;
      /* Non-zero if the piece is known to be in memory and on
	 the program's stack.  */
      bool in_stack_memory;
    } mem;

    /* The piece's register number, for DWARF_VALUE_REGISTER pieces.  */
    int regno;

    /* The piece's literal value, for DWARF_VALUE_STACK pieces.  */
    struct value *value;

    struct
    {
      /* A pointer to the data making up this piece,
	 for DWARF_VALUE_LITERAL pieces.  */
      const gdb_byte *data;
      /* The length of the available data.  */
      ULONGEST length;
    } literal;

    /* Used for DWARF_VALUE_IMPLICIT_POINTER.  */
    struct
    {
      /* The referent DIE from DW_OP_implicit_pointer.  */
      sect_offset die_sect_off;
      /* The byte offset into the resulting data.  */
      LONGEST offset;
    } ptr;
  } v;

  /* The length of the piece, in bits.  */
  ULONGEST size;
  /* The piece offset, in bits.  */
  ULONGEST offset;
};

/* The dwarf expression stack.  */

struct dwarf_stack_value
{
  struct value *value;

  /* True if the piece is in memory and is known to be on the program's stack.
     It is always ok to set this to zero.  This is used, for example, to
     optimize memory access from the target.  It can vastly speed up backtraces
     on long latency connections when "set stack-cache on".  */
  bool in_stack_memory;
};

/* The expression evaluator works with a dwarf_expr_context, describing
   its current state and its callbacks.  */
struct dwarf_expr_context
{
  dwarf_expr_context ();
  virtual ~dwarf_expr_context ();

  void push_address (CORE_ADDR value, bool in_stack_memory);
  void eval (const gdb_byte *addr, size_t len);
  struct value *fetch (int n);
  CORE_ADDR fetch_address (int n);
  bool fetch_in_stack_memory (int n);

  /* The stack of values, allocated with xmalloc.  */
  struct dwarf_stack_value *stack;

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

  /* Target architecture to use for address operations.  */
  struct gdbarch *gdbarch;

  /* Target address size in bytes.  */
  int addr_size;

  /* DW_FORM_ref_addr size in bytes.  If -1 DWARF is executed from a frame
     context and operations depending on DW_FORM_ref_addr are not allowed.  */
  int ref_addr_size;

  /* Offset used to relocate DW_OP_addr and DW_OP_GNU_addr_index arguments.  */
  CORE_ADDR offset;

  /* 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;

  /* Location of the value.  */
  enum dwarf_value_location location;

  /* For DWARF_VALUE_LITERAL, the current literal value's length and
     data.  For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the
     target DIE of sect_offset kind.  */
  ULONGEST len;
  const gdb_byte *data;

  /* Initialization status of variable: Non-zero if variable has been
     initialized; zero otherwise.  */
  int initialized;

  /* A vector of pieces.

     Each time DW_OP_piece is executed, we add a new element to the
     end of this array, recording the current top of the stack, the
     current location, and the size given as the operand to
     DW_OP_piece.  We then pop the top value from the stack, reset the
     location, and resume evaluation.

     The Dwarf spec doesn't say whether DW_OP_piece pops the top value
     from the stack.  We do, ensuring that clients of this interface
     expecting to see a value left on the top of the stack (say, code
     evaluating frame base expressions or CFA's specified with
     DW_CFA_def_cfa_expression) will get an error if the expression
     actually marks all the values it computes as pieces.

     If an expression never uses DW_OP_piece, num_pieces will be zero.
     (It would be nice to present these cases as expressions yielding
     a single piece, so that callers need not distinguish between the
     no-DW_OP_piece and one-DW_OP_piece cases.  But expressions with
     no DW_OP_piece operations have no value to place in a piece's
     'size' field; the size comes from the surrounding data.  So the
     two cases need to be handled separately.)  */
  std::vector<dwarf_expr_piece> pieces;

  /* Return the value of register number REGNUM (a DWARF register number),
     read as an address.  */
  virtual CORE_ADDR read_addr_from_reg (int regnum) = 0;

  /* Return a value of type TYPE, stored in register number REGNUM
     of the frame associated to the given BATON.

     REGNUM is a DWARF register number.  */
  virtual struct value *get_reg_value (struct type *type, int regnum) = 0;

  /* Read LENGTH bytes at ADDR into BUF.  */
  virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) = 0;

  /* 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.  */
  virtual void get_frame_base (const gdb_byte **start, size_t *length) = 0;

  /* Return the CFA for the frame.  */
  virtual CORE_ADDR get_frame_cfa () = 0;

  /* Return the PC for the frame.  */
  virtual CORE_ADDR get_frame_pc ()
  {
    error (_("%s is invalid in this context"), "DW_OP_implicit_pointer");
  }

  /* Return the thread-local storage address for
     DW_OP_GNU_push_tls_address or DW_OP_form_tls_address.  */
  virtual CORE_ADDR get_tls_address (CORE_ADDR offset) = 0;

  /* Execute DW_AT_location expression for the DWARF expression
     subroutine in the DIE at DIE_CU_OFF in the CU.  Do not touch
     STACK while it being passed to and returned from the called DWARF
     subroutine.  */
  virtual void dwarf_call (cu_offset die_cu_off) = 0;

  /* Return the base type given by the indicated DIE at DIE_CU_OFF.
     This can throw an exception if the DIE is invalid or does not
     represent a base type.  SIZE is non-zero if this function should
     verify that the resulting type has the correct size.  */
  virtual struct type *get_base_type (cu_offset die_cu_off, int size)
  {
    /* Anything will do.  */
    return builtin_type (this->gdbarch)->builtin_int;
  }

  /* Push on DWARF stack an entry evaluated for DW_TAG_call_site's
     parameter matching KIND and KIND_U at the caller of specified BATON.
     If DEREF_SIZE is not -1 then use DW_AT_call_data_value instead of
     DW_AT_call_value.  */
  virtual void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind,
					   union call_site_parameter_u kind_u,
					   int deref_size) = 0;

  /* Return the address indexed by DW_OP_GNU_addr_index.
     This can throw an exception if the index is out of range.  */
  virtual CORE_ADDR get_addr_index (unsigned int index) = 0;

  /* Return the `object address' for DW_OP_push_object_address.  */
  virtual CORE_ADDR get_object_address () = 0;

private:

  struct type *address_type () const;
  void grow_stack (size_t need);
  void push (struct value *value, bool in_stack_memory);
  bool stack_empty_p () const;
  void add_piece (ULONGEST size, ULONGEST offset);
  void execute_stack_op (const gdb_byte *op_ptr, const gdb_byte *op_end);
  void pop ();
};

void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *,
				     const char *);

int dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end);

int dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf,
				    const gdb_byte *buf_end,
				    CORE_ADDR *deref_size_return);

int dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end,
			      CORE_ADDR *fb_offset_return);

int dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf,
			      const gdb_byte *buf_end,
			      CORE_ADDR *sp_offset_return);

/* Wrappers around the leb128 reader routines to simplify them for our
   purposes.  */

static inline const gdb_byte *
gdb_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
		  uint64_t *r)
{
  size_t bytes_read = read_uleb128_to_uint64 (buf, buf_end, r);

  if (bytes_read == 0)
    return NULL;
  return buf + bytes_read;
}

static inline const gdb_byte *
gdb_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
		  int64_t *r)
{
  size_t bytes_read = read_sleb128_to_int64 (buf, buf_end, r);

  if (bytes_read == 0)
    return NULL;
  return buf + bytes_read;
}

static inline const gdb_byte *
gdb_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end)
{
  size_t bytes_read = skip_leb128 (buf, buf_end);

  if (bytes_read == 0)
    return NULL;
  return buf + bytes_read;
}

extern const gdb_byte *safe_read_uleb128 (const gdb_byte *buf,
					  const gdb_byte *buf_end,
					  uint64_t *r);

extern const gdb_byte *safe_read_sleb128 (const gdb_byte *buf,
					  const gdb_byte *buf_end,
					  int64_t *r);

extern const gdb_byte *safe_skip_leb128 (const gdb_byte *buf,
					 const gdb_byte *buf_end);

#endif /* dwarf2expr.h */
Commit	Line	Data
852483bc MK	1	/* DWARF 2 Expression Evaluator.
852483bc MK	2
61baf725	3	Copyright (C) 2001-2017 Free Software Foundation, Inc.
852483bc MK	4
	5	Contributed by Daniel Berlin <dan@dberlin.org>.
	6
4c2df51b DJ	7	This file is part of GDB.
	8
	9	This program is free software; you can redistribute it and/or modify
	10	it under the terms of the GNU General Public License as published by
a9762ec7	11	the Free Software Foundation; either version 3 of the License, or
4c2df51b DJ	12	(at your option) any later version.
	13
	14	This program is distributed in the hope that it will be useful,
	15	but WITHOUT ANY WARRANTY; without even the implied warranty of
	16	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	17	GNU General Public License for more details.
	18
	19	You should have received a copy of the GNU General Public License
a9762ec7	20	along with this program. If not, see <http://www.gnu.org/licenses/>. */
4c2df51b DJ	21
	22	#if !defined (DWARF2EXPR_H)
	23	#define DWARF2EXPR_H
	24
f664829e	25	#include "leb128.h"
836bf454	26	#include "gdbtypes.h"
f664829e	27
cec03d70 TT	28	/* The location of a value. */
	29	enum dwarf_value_location
	30	{
44353522 DE	31	/* The piece is in memory.
44353522 DE	32	The value on the dwarf stack is its address. */
cec03d70	33	DWARF_VALUE_MEMORY,
44353522 DE	34
	35	/* The piece is in a register.
	36	The value on the dwarf stack is the register number. */
cec03d70	37	DWARF_VALUE_REGISTER,
44353522 DE	38
44353522 DE	39	/* The piece is on the dwarf stack. */
cec03d70	40	DWARF_VALUE_STACK,
44353522	41
cec03d70	42	/* The piece is a literal. */
cb826367 TT	43	DWARF_VALUE_LITERAL,
	44
	45	/* The piece was optimized out. */
8cf6f0b1 TT	46	DWARF_VALUE_OPTIMIZED_OUT,
	47
	48	/* The piece is an implicit pointer. */
	49	DWARF_VALUE_IMPLICIT_POINTER
cec03d70 TT	50	};
cec03d70 TT	51
1e467161 SM	52	/* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */
	53	struct dwarf_expr_piece
	54	{
	55	enum dwarf_value_location location;
	56
	57	union
	58	{
	59	struct
	60	{
	61	/* This piece's address, for DWARF_VALUE_MEMORY pieces. */
	62	CORE_ADDR addr;
	63	/* Non-zero if the piece is known to be in memory and on
	64	the program's stack. */
69009882	65	bool in_stack_memory;
1e467161 SM	66	} mem;
	67
	68	/* The piece's register number, for DWARF_VALUE_REGISTER pieces. */
	69	int regno;
	70
	71	/* The piece's literal value, for DWARF_VALUE_STACK pieces. */
	72	struct value *value;
	73
	74	struct
	75	{
	76	/* A pointer to the data making up this piece,
	77	for DWARF_VALUE_LITERAL pieces. */
	78	const gdb_byte *data;
	79	/* The length of the available data. */
	80	ULONGEST length;
	81	} literal;
	82
	83	/* Used for DWARF_VALUE_IMPLICIT_POINTER. */
	84	struct
	85	{
	86	/* The referent DIE from DW_OP_implicit_pointer. */
	87	sect_offset die_sect_off;
	88	/* The byte offset into the resulting data. */
	89	LONGEST offset;
	90	} ptr;
	91	} v;
	92
	93	/* The length of the piece, in bits. */
	94	ULONGEST size;
	95	/* The piece offset, in bits. */
	96	ULONGEST offset;
	97	};
	98
44353522 DE	99	/* The dwarf expression stack. */
	100
	101	struct dwarf_stack_value
	102	{
8a9b8146	103	struct value *value;
44353522	104
69009882 SM	105	/* True if the piece is in memory and is known to be on the program's stack.
	106	It is always ok to set this to zero. This is used, for example, to
	107	optimize memory access from the target. It can vastly speed up backtraces
	108	on long latency connections when "set stack-cache on". */
	109	bool in_stack_memory;
44353522 DE	110	};
44353522 DE	111
4c2df51b DJ	112	/* The expression evaluator works with a dwarf_expr_context, describing
	113	its current state and its callbacks. */
	114	struct dwarf_expr_context
	115	{
718b9626	116	dwarf_expr_context ();
beb18c86	117	virtual ~dwarf_expr_context ();
718b9626	118
69009882	119	void push_address (CORE_ADDR value, bool in_stack_memory);
595d2e30 TT	120	void eval (const gdb_byte *addr, size_t len);
	121	struct value *fetch (int n);
	122	CORE_ADDR fetch_address (int n);
69009882	123	bool fetch_in_stack_memory (int n);
595d2e30	124
4c2df51b	125	/* The stack of values, allocated with xmalloc. */
44353522	126	struct dwarf_stack_value *stack;
4c2df51b DJ	127
	128	/* The number of values currently pushed on the stack, and the
	129	number of elements allocated to the stack. */
	130	int stack_len, stack_allocated;
	131
f7fd4728 UW	132	/* Target architecture to use for address operations. */
	133	struct gdbarch *gdbarch;
	134
ae0d2f24 UW	135	/* Target address size in bytes. */
	136	int addr_size;
	137
181cebd4 JK	138	/* DW_FORM_ref_addr size in bytes. If -1 DWARF is executed from a frame
	139	context and operations depending on DW_FORM_ref_addr are not allowed. */
	140	int ref_addr_size;
	141
49f6c839	142	/* Offset used to relocate DW_OP_addr and DW_OP_GNU_addr_index arguments. */
ac56253d TT	143	CORE_ADDR offset;
ac56253d TT	144
4c2df51b DJ	145	/* The current depth of dwarf expression recursion, via DW_OP_call*,
	146	DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
	147	depth we'll tolerate before raising an error. */
	148	int recursion_depth, max_recursion_depth;
	149
cec03d70 TT	150	/* Location of the value. */
	151	enum dwarf_value_location location;
	152
766062f6	153	/* For DWARF_VALUE_LITERAL, the current literal value's length and
8cf6f0b1	154	data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the
8b9737bf	155	target DIE of sect_offset kind. */
cec03d70	156	ULONGEST len;
0d45f56e	157	const gdb_byte *data;
87808bd6	158
42be36b3 CT	159	/* Initialization status of variable: Non-zero if variable has been
	160	initialized; zero otherwise. */
	161	int initialized;
	162
1e467161	163	/* A vector of pieces.
87808bd6 JB	164
	165	Each time DW_OP_piece is executed, we add a new element to the
	166	end of this array, recording the current top of the stack, the
cec03d70	167	current location, and the size given as the operand to
44353522	168	DW_OP_piece. We then pop the top value from the stack, reset the
cec03d70	169	location, and resume evaluation.
87808bd6 JB	170
	171	The Dwarf spec doesn't say whether DW_OP_piece pops the top value
	172	from the stack. We do, ensuring that clients of this interface
	173	expecting to see a value left on the top of the stack (say, code
	174	evaluating frame base expressions or CFA's specified with
	175	DW_CFA_def_cfa_expression) will get an error if the expression
	176	actually marks all the values it computes as pieces.
	177
	178	If an expression never uses DW_OP_piece, num_pieces will be zero.
	179	(It would be nice to present these cases as expressions yielding
cec03d70 TT	180	a single piece, so that callers need not distinguish between the
	181	no-DW_OP_piece and one-DW_OP_piece cases. But expressions with
	182	no DW_OP_piece operations have no value to place in a piece's
	183	'size' field; the size comes from the surrounding data. So the
	184	two cases need to be handled separately.) */
1e467161	185	std::vector<dwarf_expr_piece> pieces;
595d2e30	186
192ca6d8 TT	187	/* Return the value of register number REGNUM (a DWARF register number),
	188	read as an address. */
	189	virtual CORE_ADDR read_addr_from_reg (int regnum) = 0;
	190
	191	/* Return a value of type TYPE, stored in register number REGNUM
	192	of the frame associated to the given BATON.
	193
	194	REGNUM is a DWARF register number. */
	195	virtual struct value get_reg_value (struct type type, int regnum) = 0;
	196
	197	/* Read LENGTH bytes at ADDR into BUF. */
	198	virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) = 0;
	199
	200	/* Return the location expression for the frame base attribute, in
	201	START and LENGTH. The result must be live until the current
	202	expression evaluation is complete. */
befbff86	203	virtual void get_frame_base (const gdb_byte *start, size_t length) = 0;
192ca6d8 TT	204
192ca6d8 TT	205	/* Return the CFA for the frame. */
befbff86	206	virtual CORE_ADDR get_frame_cfa () = 0;
192ca6d8 TT	207
	208	/* Return the PC for the frame. */
	209	virtual CORE_ADDR get_frame_pc ()
	210	{
216f72a1	211	error (_("%s is invalid in this context"), "DW_OP_implicit_pointer");
192ca6d8 TT	212	}
	213
	214	/* Return the thread-local storage address for
	215	DW_OP_GNU_push_tls_address or DW_OP_form_tls_address. */
befbff86	216	virtual CORE_ADDR get_tls_address (CORE_ADDR offset) = 0;
192ca6d8 TT	217
192ca6d8 TT	218	/* Execute DW_AT_location expression for the DWARF expression
9c541725	219	subroutine in the DIE at DIE_CU_OFF in the CU. Do not touch
192ca6d8 TT	220	STACK while it being passed to and returned from the called DWARF
192ca6d8 TT	221	subroutine. */
9c541725	222	virtual void dwarf_call (cu_offset die_cu_off) = 0;
192ca6d8	223
9c541725 PA	224	/* Return the base type given by the indicated DIE at DIE_CU_OFF.
	225	This can throw an exception if the DIE is invalid or does not
	226	represent a base type. SIZE is non-zero if this function should
	227	verify that the resulting type has the correct size. */
	228	virtual struct type *get_base_type (cu_offset die_cu_off, int size)
192ca6d8 TT	229	{
	230	/* Anything will do. */
	231	return builtin_type (this->gdbarch)->builtin_int;
	232	}
	233
216f72a1	234	/* Push on DWARF stack an entry evaluated for DW_TAG_call_site's
192ca6d8	235	parameter matching KIND and KIND_U at the caller of specified BATON.
216f72a1 JK	236	If DEREF_SIZE is not -1 then use DW_AT_call_data_value instead of
216f72a1 JK	237	DW_AT_call_value. */
192ca6d8 TT	238	virtual void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind,
192ca6d8 TT	239	union call_site_parameter_u kind_u,
befbff86	240	int deref_size) = 0;
192ca6d8 TT	241
	242	/* Return the address indexed by DW_OP_GNU_addr_index.
	243	This can throw an exception if the index is out of range. */
befbff86	244	virtual CORE_ADDR get_addr_index (unsigned int index) = 0;
192ca6d8 TT	245
192ca6d8 TT	246	/* Return the `object address' for DW_OP_push_object_address. */
befbff86	247	virtual CORE_ADDR get_object_address () = 0;
192ca6d8	248
595d2e30 TT	249	private:
	250
	251	struct type *address_type () const;
	252	void grow_stack (size_t need);
69009882	253	void push (struct value *value, bool in_stack_memory);
eccd80d6	254	bool stack_empty_p () const;
595d2e30	255	void add_piece (ULONGEST size, ULONGEST offset);
595d2e30 TT	256	void execute_stack_op (const gdb_byte op_ptr, const gdb_byte op_end);
595d2e30 TT	257	void pop ();
87808bd6 JB	258	};
87808bd6 JB	259
3cf03773 TT	260	void dwarf_expr_require_composition (const gdb_byte , const gdb_byte ,
	261	const char *);
	262
8e3b41a9	263	int dwarf_block_to_dwarf_reg (const gdb_byte buf, const gdb_byte buf_end);
523f3620	264
a471c594 JK	265	int dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf,
	266	const gdb_byte *buf_end,
	267	CORE_ADDR *deref_size_return);
	268
e18b2753 JK	269	int dwarf_block_to_fb_offset (const gdb_byte buf, const gdb_byte buf_end,
	270	CORE_ADDR *fb_offset_return);
	271
	272	int dwarf_block_to_sp_offset (struct gdbarch gdbarch, const gdb_byte buf,
	273	const gdb_byte *buf_end,
	274	CORE_ADDR *sp_offset_return);
	275
f664829e DE	276	/* Wrappers around the leb128 reader routines to simplify them for our
	277	purposes. */
	278
	279	static inline const gdb_byte *
	280	gdb_read_uleb128 (const gdb_byte buf, const gdb_byte buf_end,
9fccedf7	281	uint64_t *r)
f664829e	282	{
9fccedf7	283	size_t bytes_read = read_uleb128_to_uint64 (buf, buf_end, r);
f664829e DE	284
	285	if (bytes_read == 0)
	286	return NULL;
	287	return buf + bytes_read;
	288	}
	289
	290	static inline const gdb_byte *
	291	gdb_read_sleb128 (const gdb_byte buf, const gdb_byte buf_end,
9fccedf7	292	int64_t *r)
f664829e	293	{
9fccedf7	294	size_t bytes_read = read_sleb128_to_int64 (buf, buf_end, r);
f664829e DE	295
	296	if (bytes_read == 0)
	297	return NULL;
	298	return buf + bytes_read;
	299	}
	300
	301	static inline const gdb_byte *
	302	gdb_skip_leb128 (const gdb_byte buf, const gdb_byte buf_end)
	303	{
	304	size_t bytes_read = skip_leb128 (buf, buf_end);
	305
	306	if (bytes_read == 0)
	307	return NULL;
	308	return buf + bytes_read;
	309	}
	310
	311	extern const gdb_byte safe_read_uleb128 (const gdb_byte buf,
	312	const gdb_byte *buf_end,
9fccedf7	313	uint64_t *r);
f664829e DE	314
	315	extern const gdb_byte safe_read_sleb128 (const gdb_byte buf,
	316	const gdb_byte *buf_end,
9fccedf7	317	int64_t *r);
f664829e DE	318
	319	extern const gdb_byte safe_skip_leb128 (const gdb_byte buf,
	320	const gdb_byte *buf_end);
	321
852483bc	322	#endif /* dwarf2expr.h */