/* Frame unwinder for frames with DWARF Call Frame Information.

   Copyright (C) 2003-2017 Free Software Foundation, Inc.

   Contributed by Mark Kettenis.

   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/>.  */

#ifndef DWARF2_FRAME_H
#define DWARF2_FRAME_H 1

struct gdbarch;
struct objfile;
struct frame_info;
struct dwarf2_per_cu_data;
struct agent_expr;
struct axs_value;

/* Register rule.  */

enum dwarf2_frame_reg_rule
{
  /* Make certain that 0 maps onto the correct enum value; the
     corresponding structure is being initialized using memset zero.
     This indicates that CFI didn't provide any information at all
     about a register, leaving how to obtain its value totally
     unspecified.  */
  DWARF2_FRAME_REG_UNSPECIFIED = 0,

  /* The term "undefined" comes from the DWARF2 CFI spec which this
     code is moddeling; it indicates that the register's value is
     "undefined".  GCC uses the less formal term "unsaved".  Its
     definition is a combination of REG_UNDEFINED and REG_UNSPECIFIED.
     The failure to differentiate the two helps explain a few problems
     with the CFI generated by GCC.  */
  DWARF2_FRAME_REG_UNDEFINED,
  DWARF2_FRAME_REG_SAVED_OFFSET,
  DWARF2_FRAME_REG_SAVED_REG,
  DWARF2_FRAME_REG_SAVED_EXP,
  DWARF2_FRAME_REG_SAME_VALUE,

  /* These are defined in Dwarf3.  */
  DWARF2_FRAME_REG_SAVED_VAL_OFFSET,
  DWARF2_FRAME_REG_SAVED_VAL_EXP,

  /* These aren't defined by the DWARF2 CFI specification, but are
     used internally by GDB.  */
  DWARF2_FRAME_REG_FN,		/* Call a registered function.  */
  DWARF2_FRAME_REG_RA,		/* Return Address.  */
  DWARF2_FRAME_REG_RA_OFFSET,	/* Return Address with offset.  */
  DWARF2_FRAME_REG_CFA,		/* Call Frame Address.  */
  DWARF2_FRAME_REG_CFA_OFFSET	/* Call Frame Address with offset.  */
};

/* Register state.  */

struct dwarf2_frame_state_reg
{
  /* Each register save state can be described in terms of a CFA slot,
     another register, or a location expression.  */
  union {
    LONGEST offset;
    ULONGEST reg;
    const gdb_byte *exp;
    struct value *(*fn) (struct frame_info *this_frame, void **this_cache,
			 int regnum);
  } loc;
  ULONGEST exp_len;
  enum dwarf2_frame_reg_rule how;
};

enum cfa_how_kind
{
  CFA_UNSET,
  CFA_REG_OFFSET,
  CFA_EXP
};

struct dwarf2_frame_state_reg_info
{
  struct dwarf2_frame_state_reg *reg;
  int num_regs;

  LONGEST cfa_offset;
  ULONGEST cfa_reg;
  enum cfa_how_kind cfa_how;
  const gdb_byte *cfa_exp;

  /* Used to implement DW_CFA_remember_state.  */
  struct dwarf2_frame_state_reg_info *prev;
};

/* Structure describing a frame state.  */

struct dwarf2_frame_state
{
  /* Each register save state can be described in terms of a CFA slot,
     another register, or a location expression.  */
  struct dwarf2_frame_state_reg_info regs;

  /* The PC described by the current frame state.  */
  CORE_ADDR pc;

  /* Initial register set from the CIE.
     Used to implement DW_CFA_restore.  */
  struct dwarf2_frame_state_reg_info initial;

  /* The information we care about from the CIE.  */
  LONGEST data_align;
  ULONGEST code_align;
  ULONGEST retaddr_column;

  /* Flags for known producer quirks.  */

  /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa
     and DW_CFA_def_cfa_offset takes a factored offset.  */
  int armcc_cfa_offsets_sf;

  /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that
     the CFA is defined as REG - OFFSET rather than REG + OFFSET.  */
  int armcc_cfa_offsets_reversed;
};

/* Set the architecture-specific register state initialization
   function for GDBARCH to INIT_REG.  */

extern void dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
				       void (*init_reg) (struct gdbarch *, int,
					     struct dwarf2_frame_state_reg *,
					     struct frame_info *));

/* Set the architecture-specific signal trampoline recognition
   function for GDBARCH to SIGNAL_FRAME_P.  */

extern void
  dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
				   int (*signal_frame_p) (struct gdbarch *,
							  struct frame_info *));

/* Set the architecture-specific adjustment of .eh_frame and .debug_frame
   register numbers.  */

extern void
  dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
				  int (*adjust_regnum) (struct gdbarch *,
							int, int));

/* Append the DWARF-2 frame unwinders to GDBARCH's list.  */

void dwarf2_append_unwinders (struct gdbarch *gdbarch);

/* Return the frame base methods for the function that contains PC, or
   NULL if it can't be handled by the DWARF CFI frame unwinder.  */

extern const struct frame_base *
  dwarf2_frame_base_sniffer (struct frame_info *this_frame);

/* Compute the DWARF CFA for a frame.  */

CORE_ADDR dwarf2_frame_cfa (struct frame_info *this_frame);

/* Assert that the register set RS is large enough to store gdbarch_num_regs
   columns.  If necessary, enlarge the register set.  */

void dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
				    int num_regs);

/* Find the CFA information for PC.

   Return 1 if a register is used for the CFA, or 0 if another
   expression is used.  Throw an exception on error.

   GDBARCH is the architecture to use.
   DATA is the per-CU data.

   REGNUM_OUT is an out parameter that is set to the register number.
   OFFSET_OUT is the offset to use from this register.
   These are only filled in when 1 is returned.

   TEXT_OFFSET_OUT, CFA_START_OUT, and CFA_END_OUT describe the CFA
   in other cases.  These are only used when 0 is returned.  */

extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
				  struct dwarf2_per_cu_data *data,
				  int *regnum_out, LONGEST *offset_out,
				  CORE_ADDR *text_offset_out,
				  const gdb_byte **cfa_start_out,
				  const gdb_byte **cfa_end_out);

#endif /* dwarf2-frame.h */