binutils-gdb/gdb/stack.c

/* Print and select stack frames for GDB, the GNU debugger.

   Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007
   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 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., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.  */

#include "defs.h"
#include "value.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "expression.h"
#include "language.h"
#include "frame.h"
#include "gdbcmd.h"
#include "gdbcore.h"
#include "target.h"
#include "source.h"
#include "breakpoint.h"
#include "demangle.h"
#include "inferior.h"
#include "annotate.h"
#include "ui-out.h"
#include "block.h"
#include "stack.h"
#include "dictionary.h"
#include "exceptions.h"
#include "reggroups.h"
#include "regcache.h"
#include "solib.h"
#include "valprint.h"

#include "gdb_assert.h"
#include <ctype.h>
#include "gdb_string.h"

void (*deprecated_selected_frame_level_changed_hook) (int);

/* Prototypes for local functions. */

static void print_frame_local_vars (struct frame_info *, int,
				    struct ui_file *);

static void print_frame (struct frame_info *frame, int print_level,
			 enum print_what print_what,  int print_args,
			 struct symtab_and_line sal);

/* Zero means do things normally; we are interacting directly with the
   user.  One means print the full filename and linenumber when a
   frame is printed, and do so in a format emacs18/emacs19.22 can
   parse.  Two means print similar annotations, but in many more
   cases and in a slightly different syntax.  */

int annotation_level = 0;


struct print_stack_frame_args
{
  struct frame_info *frame;
  int print_level;
  enum print_what print_what;
  int print_args;
};

/* Show or print the frame arguments; stub for catch_errors.  */

static int
print_stack_frame_stub (void *args)
{
  struct print_stack_frame_args *p = args;
  int center = (p->print_what == SRC_LINE || p->print_what == SRC_AND_LOC);

  print_frame_info (p->frame, p->print_level, p->print_what, p->print_args);
  set_current_sal_from_frame (p->frame, center);
  return 0;
}

/* Show or print a stack frame FRAME briefly.  The output is format
   according to PRINT_LEVEL and PRINT_WHAT printing the frame's
   relative level, function name, argument list, and file name and
   line number.  If the frame's PC is not at the beginning of the
   source line, the actual PC is printed at the beginning.  */

void
print_stack_frame (struct frame_info *frame, int print_level,
		   enum print_what print_what)
{
  struct print_stack_frame_args args;

  args.frame = frame;
  args.print_level = print_level;
  args.print_what = print_what;
  /* For mi, alway print location and address.  */
  args.print_what = ui_out_is_mi_like_p (uiout) ? LOC_AND_ADDRESS : print_what;
  args.print_args = 1;

  catch_errors (print_stack_frame_stub, &args, "", RETURN_MASK_ALL);
}  

struct print_args_args
{
  struct symbol *func;
  struct frame_info *frame;
  struct ui_file *stream;
};

static int print_args_stub (void *args);

/* Print nameless arguments of frame FRAME on STREAM, where START is
   the offset of the first nameless argument, and NUM is the number of
   nameless arguments to print.  FIRST is nonzero if this is the first
   argument (not just the first nameless argument).  */

static void
print_frame_nameless_args (struct frame_info *frame, long start, int num,
			   int first, struct ui_file *stream)
{
  int i;
  CORE_ADDR argsaddr;
  long arg_value;

  for (i = 0; i < num; i++)
    {
      QUIT;
      argsaddr = get_frame_args_address (frame);
      if (!argsaddr)
	return;
      arg_value = read_memory_integer (argsaddr + start, sizeof (int));
      if (!first)
	fprintf_filtered (stream, ", ");
      fprintf_filtered (stream, "%ld", arg_value);
      first = 0;
      start += sizeof (int);
    }
}

/* Print the arguments of frame FRAME on STREAM, given the function
   FUNC running in that frame (as a symbol), where NUM is the number
   of arguments according to the stack frame (or -1 if the number of
   arguments is unknown).  */

/* Note that currently the "number of argumentss according to the
   stack frame" is only known on VAX where i refers to the "number of
   ints of argumentss according to the stack frame".  */

static void
print_frame_args (struct symbol *func, struct frame_info *frame,
		  int num, struct ui_file *stream)
{
  int first = 1;
  /* Offset of next stack argument beyond the one we have seen that is
     at the highest offset, or -1 if we haven't come to a stack
     argument yet.  */
  long highest_offset = -1;
  /* Number of ints of arguments that we have printed so far.  */
  int args_printed = 0;
  struct cleanup *old_chain, *list_chain;
  struct ui_stream *stb;

  stb = ui_out_stream_new (uiout);
  old_chain = make_cleanup_ui_out_stream_delete (stb);

  if (func)
    {
      struct block *b = SYMBOL_BLOCK_VALUE (func);
      struct dict_iterator iter;
      struct symbol *sym;
      struct value *val;

      ALL_BLOCK_SYMBOLS (b, iter, sym)
        {
	  QUIT;

	  /* Keep track of the highest stack argument offset seen, and
	     skip over any kinds of symbols we don't care about.  */

	  switch (SYMBOL_CLASS (sym))
	    {
	    case LOC_ARG:
	    case LOC_REF_ARG:
	      {
		long current_offset = SYMBOL_VALUE (sym);
		int arg_size = TYPE_LENGTH (SYMBOL_TYPE (sym));

		/* Compute address of next argument by adding the size of
		   this argument and rounding to an int boundary.  */
		current_offset =
		  ((current_offset + arg_size + sizeof (int) - 1)
		   & ~(sizeof (int) - 1));

		/* If this is the highest offset seen yet, set
		   highest_offset.  */
		if (highest_offset == -1
		    || (current_offset > highest_offset))
		  highest_offset = current_offset;

		/* Add the number of ints we're about to print to
		   args_printed.  */
		args_printed += (arg_size + sizeof (int) - 1) / sizeof (int);
	      }

	      /* We care about types of symbols, but don't need to
		 keep track of stack offsets in them.  */
	    case LOC_REGPARM:
	    case LOC_REGPARM_ADDR:
	    case LOC_LOCAL_ARG:
	    case LOC_BASEREG_ARG:
	    case LOC_COMPUTED_ARG:
	      break;

	    /* Other types of symbols we just skip over.  */
	    default:
	      continue;
	    }

	  /* We have to look up the symbol because arguments can have
	     two entries (one a parameter, one a local) and the one we
	     want is the local, which lookup_symbol will find for us.
	     This includes gcc1 (not gcc2) on SPARC when passing a
	     small structure and gcc2 when the argument type is float
	     and it is passed as a double and converted to float by
	     the prologue (in the latter case the type of the LOC_ARG
	     symbol is double and the type of the LOC_LOCAL symbol is
	     float).  */
	  /* But if the parameter name is null, don't try it.  Null
	     parameter names occur on the RS/6000, for traceback
	     tables.  FIXME, should we even print them?  */

	  if (*DEPRECATED_SYMBOL_NAME (sym))
	    {
	      struct symbol *nsym;
	      nsym = lookup_symbol (DEPRECATED_SYMBOL_NAME (sym),
				    b, VAR_DOMAIN, NULL, NULL);
	      if (SYMBOL_CLASS (nsym) == LOC_REGISTER)
		{
		  /* There is a LOC_ARG/LOC_REGISTER pair.  This means
		     that it was passed on the stack and loaded into a
		     register, or passed in a register and stored in a
		     stack slot.  GDB 3.x used the LOC_ARG; GDB
		     4.0-4.11 used the LOC_REGISTER.

		     Reasons for using the LOC_ARG:

		     (1) Because find_saved_registers may be slow for
		         remote debugging.

		     (2) Because registers are often re-used and stack
		         slots rarely (never?) are.  Therefore using
		         the stack slot is much less likely to print
		         garbage.

		     Reasons why we might want to use the LOC_REGISTER:

		     (1) So that the backtrace prints the same value
		         as "print foo".  I see no compelling reason
		         why this needs to be the case; having the
		         backtrace print the value which was passed
		         in, and "print foo" print the value as
		         modified within the called function, makes
		         perfect sense to me.

		     Additional note: It might be nice if "info args"
		     displayed both values.

		     One more note: There is a case with SPARC
		     structure passing where we need to use the
		     LOC_REGISTER, but this is dealt with by creating
		     a single LOC_REGPARM in symbol reading.  */

		  /* Leave sym (the LOC_ARG) alone.  */
		  ;
		}
	      else
		sym = nsym;
	    }

	  /* Print the current arg.  */
	  if (!first)
	    ui_out_text (uiout, ", ");
	  ui_out_wrap_hint (uiout, "    ");

	  annotate_arg_begin ();

	  list_chain = make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
	  fprintf_symbol_filtered (stb->stream, SYMBOL_PRINT_NAME (sym),
				   SYMBOL_LANGUAGE (sym),
				   DMGL_PARAMS | DMGL_ANSI);
	  ui_out_field_stream (uiout, "name", stb);
	  annotate_arg_name_end ();
	  ui_out_text (uiout, "=");

	  /* Avoid value_print because it will deref ref parameters.
	     We just want to print their addresses.  Print ??? for
	     args whose address we do not know.  We pass 2 as
	     "recurse" to val_print because our standard indentation
	     here is 4 spaces, and val_print indents 2 for each
	     recurse.  */
	  val = read_var_value (sym, frame);

	  annotate_arg_value (val == NULL ? NULL : value_type (val));

	  if (val)
	    {
	      common_val_print (val, stb->stream, 0, 0, 2, Val_no_prettyprint);
	      ui_out_field_stream (uiout, "value", stb);
	    }
	  else
	    ui_out_text (uiout, "???");

	  /* Invoke ui_out_tuple_end.  */
	  do_cleanups (list_chain);

	  annotate_arg_end ();

	  first = 0;
	}
    }

  /* Don't print nameless args in situations where we don't know
     enough about the stack to find them.  */
  if (num != -1)
    {
      long start;

      if (highest_offset == -1)
	start = gdbarch_frame_args_skip (current_gdbarch);
      else
	start = highest_offset;

      print_frame_nameless_args (frame, start, num - args_printed,
				 first, stream);
    }

  do_cleanups (old_chain);
}

/* Stub for catch_errors.  */

static int
print_args_stub (void *args)
{
  struct print_args_args *p = args;
  int numargs;

  if (gdbarch_frame_num_args_p (current_gdbarch))
    {
      numargs = gdbarch_frame_num_args (current_gdbarch, p->frame);
      gdb_assert (numargs >= 0);
    }
  else
    numargs = -1;
  print_frame_args (p->func, p->frame, numargs, p->stream);
  return 0;
}

/* Set the current source and line to the location given by frame
   FRAME, if possible.  When CENTER is true, adjust so the relevant
   line is in the center of the next 'list'.  */

void
set_current_sal_from_frame (struct frame_info *frame, int center)
{
  struct symtab_and_line sal;

  find_frame_sal (frame, &sal);
  if (sal.symtab)
    {
      if (center)
        sal.line = max (sal.line - get_lines_to_list () / 2, 1);
      set_current_source_symtab_and_line (&sal);
    }
}

/* Print information about frame FRAME.  The output is format according
   to PRINT_LEVEL and PRINT_WHAT and PRINT ARGS.  The meaning of
   PRINT_WHAT is:
   
   SRC_LINE: Print only source line.
   LOCATION: Print only location.
   LOC_AND_SRC: Print location and source line.

   Used in "where" output, and to emit breakpoint or step
   messages.  */

void
print_frame_info (struct frame_info *frame, int print_level,
		  enum print_what print_what, int print_args)
{
  struct symtab_and_line sal;
  int source_print;
  int location_print;

  if (get_frame_type (frame) == DUMMY_FRAME
      || get_frame_type (frame) == SIGTRAMP_FRAME)
    {
      struct cleanup *uiout_cleanup
	= make_cleanup_ui_out_tuple_begin_end (uiout, "frame");

      annotate_frame_begin (print_level ? frame_relative_level (frame) : 0,
			    get_frame_pc (frame));

      /* Do this regardless of SOURCE because we don't have any source
         to list for this frame.  */
      if (print_level)
        {
          ui_out_text (uiout, "#");
          ui_out_field_fmt_int (uiout, 2, ui_left, "level",
				frame_relative_level (frame));
        }
      if (ui_out_is_mi_like_p (uiout))
        {
          annotate_frame_address ();
          ui_out_field_core_addr (uiout, "addr", get_frame_pc (frame));
          annotate_frame_address_end ();
        }

      if (get_frame_type (frame) == DUMMY_FRAME)
        {
          annotate_function_call ();
          ui_out_field_string (uiout, "func", "<function called from gdb>");
	}
      else if (get_frame_type (frame) == SIGTRAMP_FRAME)
        {
	  annotate_signal_handler_caller ();
          ui_out_field_string (uiout, "func", "<signal handler called>");
        }
      ui_out_text (uiout, "\n");
      annotate_frame_end ();

      do_cleanups (uiout_cleanup);
      return;
    }

  /* If FRAME is not the innermost frame, that normally means that
     FRAME->pc points to *after* the call instruction, and we want to
     get the line containing the call, never the next line.  But if
     the next frame is a SIGTRAMP_FRAME or a DUMMY_FRAME, then the
     next frame was not entered as the result of a call, and we want
     to get the line containing FRAME->pc.  */
  find_frame_sal (frame, &sal);

  location_print = (print_what == LOCATION 
		    || print_what == LOC_AND_ADDRESS
		    || print_what == SRC_AND_LOC);

  if (location_print || !sal.symtab)
    print_frame (frame, print_level, print_what, print_args, sal);

  source_print = (print_what == SRC_LINE || print_what == SRC_AND_LOC);

  if (source_print && sal.symtab)
    {
      int done = 0;
      int mid_statement = ((print_what == SRC_LINE)
			   && (get_frame_pc (frame) != sal.pc));

      if (annotation_level)
	done = identify_source_line (sal.symtab, sal.line, mid_statement,
				     get_frame_pc (frame));
      if (!done)
	{
	  if (deprecated_print_frame_info_listing_hook)
	    deprecated_print_frame_info_listing_hook (sal.symtab, 
						      sal.line, 
						      sal.line + 1, 0);
	  else
	    {
	      /* We used to do this earlier, but that is clearly
		 wrong. This function is used by many different
		 parts of gdb, including normal_stop in infrun.c,
		 which uses this to print out the current PC
		 when we stepi/nexti into the middle of a source
		 line. Only the command line really wants this
		 behavior. Other UIs probably would like the
		 ability to decide for themselves if it is desired.  */
	      if (addressprint && mid_statement)
		{
		  ui_out_field_core_addr (uiout, "addr", get_frame_pc (frame));
		  ui_out_text (uiout, "\t");
		}

	      print_source_lines (sal.symtab, sal.line, sal.line + 1, 0);
	    }
	}
    }

  if (print_what != LOCATION)
    set_default_breakpoint (1, get_frame_pc (frame), sal.symtab, sal.line);

  annotate_frame_end ();

  gdb_flush (gdb_stdout);
}

static void
print_frame (struct frame_info *frame, int print_level,
	     enum print_what print_what, int print_args,
	     struct symtab_and_line sal)
{
  struct symbol *func;
  char *funname = NULL;
  enum language funlang = language_unknown;
  struct ui_stream *stb;
  struct cleanup *old_chain, *list_chain;

  stb = ui_out_stream_new (uiout);
  old_chain = make_cleanup_ui_out_stream_delete (stb);

  func = find_pc_function (get_frame_address_in_block (frame));
  if (func)
    {
      /* In certain pathological cases, the symtabs give the wrong
         function (when we are in the first function in a file which
         is compiled without debugging symbols, the previous function
         is compiled with debugging symbols, and the "foo.o" symbol
         that is supposed to tell us where the file with debugging
         symbols ends has been truncated by ar because it is longer
         than 15 characters).  This also occurs if the user uses asm()
         to create a function but not stabs for it (in a file compiled
         with -g).

         So look in the minimal symbol tables as well, and if it comes
         up with a larger address for the function use that instead.
         I don't think this can ever cause any problems; there
         shouldn't be any minimal symbols in the middle of a function;
         if this is ever changed many parts of GDB will need to be
         changed (and we'll create a find_pc_minimal_function or some
         such).  */

      struct minimal_symbol *msymbol =
	lookup_minimal_symbol_by_pc (get_frame_address_in_block (frame));

      if (msymbol != NULL
	  && (SYMBOL_VALUE_ADDRESS (msymbol)
	      > BLOCK_START (SYMBOL_BLOCK_VALUE (func))))
	{
	  /* We also don't know anything about the function besides
	     its address and name.  */
	  func = 0;
	  funname = DEPRECATED_SYMBOL_NAME (msymbol);
	  funlang = SYMBOL_LANGUAGE (msymbol);
	}
      else
	{
	  funname = DEPRECATED_SYMBOL_NAME (func);
	  funlang = SYMBOL_LANGUAGE (func);
	  if (funlang == language_cplus)
	    {
	      /* It seems appropriate to use SYMBOL_PRINT_NAME() here,
		 to display the demangled name that we already have
		 stored in the symbol table, but we stored a version
		 with DMGL_PARAMS turned on, and here we don't want to
		 display parameters. So call the demangler again, with
		 DMGL_ANSI only.

		 Yes, printf_symbol_filtered() will again try to
		 demangle the name on the fly, but the issue is that
		 if cplus_demangle() fails here, it will fail there
		 too. So we want to catch the failure (where DEMANGLED
		 is NULL below) here, while we still have our hands on
		 the function symbol.)  */
	      char *demangled = cplus_demangle (funname, DMGL_ANSI);
	      if (demangled == NULL)
		/* If the demangler fails, try the demangled name from
		   the symbol table. That'll have parameters, but
		   that's preferable to displaying a mangled name.  */
		funname = SYMBOL_PRINT_NAME (func);
	    }
	}
    }
  else
    {
      struct minimal_symbol *msymbol = 
	lookup_minimal_symbol_by_pc (get_frame_address_in_block (frame));

      if (msymbol != NULL)
	{
	  funname = DEPRECATED_SYMBOL_NAME (msymbol);
	  funlang = SYMBOL_LANGUAGE (msymbol);
	}
    }

  annotate_frame_begin (print_level ? frame_relative_level (frame) : 0,
			get_frame_pc (frame));

  list_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "frame");

  if (print_level)
    {
      ui_out_text (uiout, "#");
      ui_out_field_fmt_int (uiout, 2, ui_left, "level",
			    frame_relative_level (frame));
    }
  if (addressprint)
    if (get_frame_pc (frame) != sal.pc || !sal.symtab
	|| print_what == LOC_AND_ADDRESS)
      {
	annotate_frame_address ();
	ui_out_field_core_addr (uiout, "addr", get_frame_pc (frame));
	annotate_frame_address_end ();
	ui_out_text (uiout, " in ");
      }
  annotate_frame_function_name ();
  fprintf_symbol_filtered (stb->stream, funname ? funname : "??",
			   funlang, DMGL_ANSI);
  ui_out_field_stream (uiout, "func", stb);
  ui_out_wrap_hint (uiout, "   ");
  annotate_frame_args ();
      
  ui_out_text (uiout, " (");
  if (print_args)
    {
      struct print_args_args args;
      struct cleanup *args_list_chain;
      args.frame = frame;
      args.func = func;
      args.stream = gdb_stdout;
      args_list_chain = make_cleanup_ui_out_list_begin_end (uiout, "args");
      catch_errors (print_args_stub, &args, "", RETURN_MASK_ALL);
      /* FIXME: ARGS must be a list. If one argument is a string it
	  will have " that will not be properly escaped.  */
      /* Invoke ui_out_tuple_end.  */
      do_cleanups (args_list_chain);
      QUIT;
    }
  ui_out_text (uiout, ")");
  if (sal.symtab && sal.symtab->filename)
    {
      annotate_frame_source_begin ();
      ui_out_wrap_hint (uiout, "   ");
      ui_out_text (uiout, " at ");
      annotate_frame_source_file ();
      ui_out_field_string (uiout, "file", sal.symtab->filename);
      if (ui_out_is_mi_like_p (uiout))
	{
	  const char *fullname = symtab_to_fullname (sal.symtab);
	  if (fullname != NULL)
	    ui_out_field_string (uiout, "fullname", fullname);
	}
      annotate_frame_source_file_end ();
      ui_out_text (uiout, ":");
      annotate_frame_source_line ();
      ui_out_field_int (uiout, "line", sal.line);
      annotate_frame_source_end ();
    }

  if (!funname || (!sal.symtab || !sal.symtab->filename))
    {
#ifdef PC_SOLIB
      char *lib = PC_SOLIB (get_frame_pc (frame));
#else
      char *lib = solib_address (get_frame_pc (frame));
#endif
      if (lib)
	{
	  annotate_frame_where ();
	  ui_out_wrap_hint (uiout, "  ");
	  ui_out_text (uiout, " from ");
	  ui_out_field_string (uiout, "from", lib);
	}
    }

  /* do_cleanups will call ui_out_tuple_end() for us.  */
  do_cleanups (list_chain);
  ui_out_text (uiout, "\n");
  do_cleanups (old_chain);
}

/* Show the frame info.  If this is the tui, it will be shown in the
   source display otherwise, nothing is done.  */

void
show_stack_frame (struct frame_info *frame)
{
}


/* Read a frame specification in whatever the appropriate format is
   from FRAME_EXP.  Call error(), printing MESSAGE, if the
   specification is in any way invalid (so this function never returns
   NULL).  When SEPECTED_P is non-NULL set its target to indicate that
   the default selected frame was used.  */

static struct frame_info *
parse_frame_specification_1 (const char *frame_exp, const char *message,
			     int *selected_frame_p)
{
  int numargs;
  struct value *args[4];
  CORE_ADDR addrs[ARRAY_SIZE (args)];

  if (frame_exp == NULL)
    numargs = 0;
  else
    {
      char *addr_string;
      struct cleanup *tmp_cleanup;

      numargs = 0;
      while (1)
	{
	  char *addr_string;
	  struct cleanup *cleanup;
	  const char *p;

	  /* Skip leading white space, bail of EOL.  */
	  while (isspace (*frame_exp))
	    frame_exp++;
	  if (!*frame_exp)
	    break;

	  /* Parse the argument, extract it, save it.  */
	  for (p = frame_exp;
	       *p && !isspace (*p);
	       p++);
	  addr_string = savestring (frame_exp, p - frame_exp);
	  frame_exp = p;
	  cleanup = make_cleanup (xfree, addr_string);
	  
	  /* NOTE: Parse and evaluate expression, but do not use
	     functions such as parse_and_eval_long or
	     parse_and_eval_address to also extract the value.
	     Instead value_as_long and value_as_address are used.
	     This avoids problems with expressions that contain
	     side-effects.  */
	  if (numargs >= ARRAY_SIZE (args))
	    error (_("Too many args in frame specification"));
	  args[numargs++] = parse_and_eval (addr_string);

	  do_cleanups (cleanup);
	}
    }

  /* If no args, default to the selected frame.  */
  if (numargs == 0)
    {
      if (selected_frame_p != NULL)
	(*selected_frame_p) = 1;
      return get_selected_frame (message);
    }

  /* None of the remaining use the selected frame.  */
  if (selected_frame_p != NULL)
    (*selected_frame_p) = 0;

  /* Assume the single arg[0] is an integer, and try using that to
     select a frame relative to current.  */
  if (numargs == 1)
    {
      struct frame_info *fid;
      int level = value_as_long (args[0]);
      fid = find_relative_frame (get_current_frame (), &level);
      if (level == 0)
	/* find_relative_frame was successful */
	return fid;
    }

  /* Convert each value into a corresponding address.  */
  {
    int i;
    for (i = 0; i < numargs; i++)
      addrs[i] = value_as_address (args[0]);
  }

  /* Assume that the single arg[0] is an address, use that to identify
     a frame with a matching ID.  Should this also accept stack/pc or
     stack/pc/special.  */
  if (numargs == 1)
    {
      struct frame_id id = frame_id_build_wild (addrs[0]);
      struct frame_info *fid;

      /* If (s)he specifies the frame with an address, he deserves
	 what (s)he gets.  Still, give the highest one that matches.
	 (NOTE: cagney/2004-10-29: Why highest, or outer-most, I don't
	 know).  */
      for (fid = get_current_frame ();
	   fid != NULL;
	   fid = get_prev_frame (fid))
	{
	  if (frame_id_eq (id, get_frame_id (fid)))
	    {
	      while (frame_id_eq (id, frame_unwind_id (fid)))
		fid = get_prev_frame (fid);
	      return fid;
	    }
	}
      }

  /* We couldn't identify the frame as an existing frame, but
     perhaps we can create one with a single argument.  */
  if (numargs == 1)
    return create_new_frame (addrs[0], 0);
  else if (numargs == 2)
    return create_new_frame (addrs[0], addrs[1]);
  else
    error (_("Too many args in frame specification"));
}

static struct frame_info *
parse_frame_specification (char *frame_exp)
{
  return parse_frame_specification_1 (frame_exp, NULL, NULL);
}

/* Print verbosely the selected frame or the frame at address
   ADDR_EXP.  Absolutely all information in the frame is printed.  */

static void
frame_info (char *addr_exp, int from_tty)
{
  struct frame_info *fi;
  struct symtab_and_line sal;
  struct symbol *func;
  struct symtab *s;
  struct frame_info *calling_frame_info;
  int i, count, numregs;
  char *funname = 0;
  enum language funlang = language_unknown;
  const char *pc_regname;
  int selected_frame_p;

  fi = parse_frame_specification_1 (addr_exp, "No stack.", &selected_frame_p);

  /* Name of the value returned by get_frame_pc().  Per comments, "pc"
     is not a good name.  */
  if (PC_REGNUM >= 0)
    /* OK, this is weird.  The PC_REGNUM hardware register's value can
       easily not match that of the internal value returned by
       get_frame_pc().  */
    pc_regname = gdbarch_register_name (current_gdbarch, PC_REGNUM);
  else
    /* But then, this is weird to.  Even without PC_REGNUM, an
       architectures will often have a hardware register called "pc",
       and that register's value, again, can easily not match
       get_frame_pc().  */
    pc_regname = "pc";

  find_frame_sal (fi, &sal);
  func = get_frame_function (fi);
  /* FIXME: cagney/2002-11-28: Why bother?  Won't sal.symtab contain
     the same value?  */
  s = find_pc_symtab (get_frame_pc (fi));
  if (func)
    {
      /* It seems appropriate to use SYMBOL_PRINT_NAME() here, to
	 display the demangled name that we already have stored in the
	 symbol table, but we stored a version with DMGL_PARAMS turned
	 on, and here we don't want to display parameters. So call the
	 demangler again, with DMGL_ANSI only.

	 Yes, printf_symbol_filtered() will again try to demangle the
	 name on the fly, but the issue is that if cplus_demangle()
	 fails here, it will fail there too. So we want to catch the
	 failure (where DEMANGLED is NULL below) here, while we still
	 have our hands on the function symbol.)  */
      funname = DEPRECATED_SYMBOL_NAME (func);
      funlang = SYMBOL_LANGUAGE (func);
      if (funlang == language_cplus)
	{
	  char *demangled = cplus_demangle (funname, DMGL_ANSI);
	  /* If the demangler fails, try the demangled name from the
	     symbol table. That'll have parameters, but that's
	     preferable to displaying a mangled name.  */
	  if (demangled == NULL)
	    funname = SYMBOL_PRINT_NAME (func);
	}
    }
  else
    {
      struct minimal_symbol *msymbol;

      msymbol = lookup_minimal_symbol_by_pc (get_frame_pc (fi));
      if (msymbol != NULL)
	{
	  funname = DEPRECATED_SYMBOL_NAME (msymbol);
	  funlang = SYMBOL_LANGUAGE (msymbol);
	}
    }
  calling_frame_info = get_prev_frame (fi);

  if (selected_frame_p && frame_relative_level (fi) >= 0)
    {
      printf_filtered (_("Stack level %d, frame at "),
		       frame_relative_level (fi));
    }
  else
    {
      printf_filtered (_("Stack frame at "));
    }
  deprecated_print_address_numeric (get_frame_base (fi), 1, gdb_stdout);
  printf_filtered (":\n");
  printf_filtered (" %s = ", pc_regname);
  deprecated_print_address_numeric (get_frame_pc (fi), 1, gdb_stdout);

  wrap_here ("   ");
  if (funname)
    {
      printf_filtered (" in ");
      fprintf_symbol_filtered (gdb_stdout, funname, funlang,
			       DMGL_ANSI | DMGL_PARAMS);
    }
  wrap_here ("   ");
  if (sal.symtab)
    printf_filtered (" (%s:%d)", sal.symtab->filename, sal.line);
  puts_filtered ("; ");
  wrap_here ("    ");
  printf_filtered ("saved %s ", pc_regname);
  deprecated_print_address_numeric (frame_pc_unwind (fi), 1, gdb_stdout);
  printf_filtered ("\n");

  if (calling_frame_info == NULL)
    {
      enum unwind_stop_reason reason;

      reason = get_frame_unwind_stop_reason (fi);
      if (reason != UNWIND_NO_REASON)
	printf_filtered (_(" Outermost frame: %s\n"),
			 frame_stop_reason_string (reason));
    }

  if (calling_frame_info)
    {
      printf_filtered (" called by frame at ");
      deprecated_print_address_numeric (get_frame_base (calling_frame_info),
			     1, gdb_stdout);
    }
  if (get_next_frame (fi) && calling_frame_info)
    puts_filtered (",");
  wrap_here ("   ");
  if (get_next_frame (fi))
    {
      printf_filtered (" caller of frame at ");
      deprecated_print_address_numeric (get_frame_base (get_next_frame (fi)), 1,
			     gdb_stdout);
    }
  if (get_next_frame (fi) || calling_frame_info)
    puts_filtered ("\n");

  if (s)
    printf_filtered (" source language %s.\n",
		     language_str (s->language));

  {
    /* Address of the argument list for this frame, or 0.  */
    CORE_ADDR arg_list = get_frame_args_address (fi);
    /* Number of args for this frame, or -1 if unknown.  */
    int numargs;

    if (arg_list == 0)
      printf_filtered (" Arglist at unknown address.\n");
    else
      {
	printf_filtered (" Arglist at ");
	deprecated_print_address_numeric (arg_list, 1, gdb_stdout);
	printf_filtered (",");

	if (!gdbarch_frame_num_args_p (current_gdbarch))
	  {
	    numargs = -1;
	    puts_filtered (" args: ");
	  }
	else
	  {
	    numargs = gdbarch_frame_num_args (current_gdbarch, fi);
	    gdb_assert (numargs >= 0);
	    if (numargs == 0)
	      puts_filtered (" no args.");
	    else if (numargs == 1)
	      puts_filtered (" 1 arg: ");
	    else
	      printf_filtered (" %d args: ", numargs);
	  }
	print_frame_args (func, fi, numargs, gdb_stdout);
	puts_filtered ("\n");
      }
  }
  {
    /* Address of the local variables for this frame, or 0.  */
    CORE_ADDR arg_list = get_frame_locals_address (fi);

    if (arg_list == 0)
      printf_filtered (" Locals at unknown address,");
    else
      {
	printf_filtered (" Locals at ");
	deprecated_print_address_numeric (arg_list, 1, gdb_stdout);
	printf_filtered (",");
      }
  }

  /* Print as much information as possible on the location of all the
     registers.  */
  {
    enum lval_type lval;
    int optimized;
    CORE_ADDR addr;
    int realnum;
    int count;
    int i;
    int need_nl = 1;

    /* The sp is special; what's displayed isn't the save address, but
       the value of the previous frame's sp.  This is a legacy thing,
       at one stage the frame cached the previous frame's SP instead
       of its address, hence it was easiest to just display the cached
       value.  */
    if (SP_REGNUM >= 0)
      {
	/* Find out the location of the saved stack pointer with out
           actually evaluating it.  */
	frame_register_unwind (fi, SP_REGNUM, &optimized, &lval, &addr,
			       &realnum, NULL);
	if (!optimized && lval == not_lval)
	  {
	    gdb_byte value[MAX_REGISTER_SIZE];
	    CORE_ADDR sp;
	    frame_register_unwind (fi, SP_REGNUM, &optimized, &lval, &addr,
				   &realnum, value);
	    /* NOTE: cagney/2003-05-22: This is assuming that the
               stack pointer was packed as an unsigned integer.  That
               may or may not be valid.  */
	    sp = extract_unsigned_integer (value, register_size (current_gdbarch, SP_REGNUM));
	    printf_filtered (" Previous frame's sp is ");
	    deprecated_print_address_numeric (sp, 1, gdb_stdout);
	    printf_filtered ("\n");
	    need_nl = 0;
	  }
	else if (!optimized && lval == lval_memory)
	  {
	    printf_filtered (" Previous frame's sp at ");
	    deprecated_print_address_numeric (addr, 1, gdb_stdout);
	    printf_filtered ("\n");
	    need_nl = 0;
	  }
	else if (!optimized && lval == lval_register)
	  {
	    printf_filtered (" Previous frame's sp in %s\n",
			     gdbarch_register_name (current_gdbarch, realnum));
	    need_nl = 0;
	  }
	/* else keep quiet.  */
      }

    count = 0;
    numregs = gdbarch_num_regs (current_gdbarch)
	      + gdbarch_num_pseudo_regs (current_gdbarch);
    for (i = 0; i < numregs; i++)
      if (i != SP_REGNUM
	  && gdbarch_register_reggroup_p (current_gdbarch, i, all_reggroup))
	{
	  /* Find out the location of the saved register without
             fetching the corresponding value.  */
	  frame_register_unwind (fi, i, &optimized, &lval, &addr, &realnum,
				 NULL);
	  /* For moment, only display registers that were saved on the
	     stack.  */
	  if (!optimized && lval == lval_memory)
	    {
	      if (count == 0)
		puts_filtered (" Saved registers:\n ");
	      else
		puts_filtered (",");
	      wrap_here (" ");
	      printf_filtered (" %s at ",
			       gdbarch_register_name (current_gdbarch, i));
	      deprecated_print_address_numeric (addr, 1, gdb_stdout);
	      count++;
	    }
	}
    if (count || need_nl)
      puts_filtered ("\n");
  }
}

/* Print briefly all stack frames or just the innermost COUNT_EXP
   frames.  */

static void
backtrace_command_1 (char *count_exp, int show_locals, int from_tty)
{
  struct frame_info *fi;
  int count;
  int i;
  struct frame_info *trailing;
  int trailing_level;

  if (!target_has_stack)
    error (_("No stack."));

  /* The following code must do two things.  First, it must set the
     variable TRAILING to the frame from which we should start
     printing.  Second, it must set the variable count to the number
     of frames which we should print, or -1 if all of them.  */
  trailing = get_current_frame ();

  /* The target can be in a state where there is no valid frames
     (e.g., just connected). */
  if (trailing == NULL)
    error (_("No stack."));

  trailing_level = 0;
  if (count_exp)
    {
      count = parse_and_eval_long (count_exp);
      if (count < 0)
	{
	  struct frame_info *current;

	  count = -count;

	  current = trailing;
	  while (current && count--)
	    {
	      QUIT;
	      current = get_prev_frame (current);
	    }

	  /* Will stop when CURRENT reaches the top of the stack.
	     TRAILING will be COUNT below it.  */
	  while (current)
	    {
	      QUIT;
	      trailing = get_prev_frame (trailing);
	      current = get_prev_frame (current);
	      trailing_level++;
	    }

	  count = -1;
	}
    }
  else
    count = -1;

  if (info_verbose)
    {
      struct partial_symtab *ps;

      /* Read in symbols for all of the frames.  Need to do this in a
         separate pass so that "Reading in symbols for xxx" messages
         don't screw up the appearance of the backtrace.  Also if
         people have strong opinions against reading symbols for
         backtrace this may have to be an option.  */
      i = count;
      for (fi = trailing; fi != NULL && i--; fi = get_prev_frame (fi))
	{
	  QUIT;
	  ps = find_pc_psymtab (get_frame_address_in_block (fi));
	  if (ps)
	    PSYMTAB_TO_SYMTAB (ps); /* Force syms to come in.  */
	}
    }

  for (i = 0, fi = trailing; fi && count--; i++, fi = get_prev_frame (fi))
    {
      QUIT;

      /* Don't use print_stack_frame; if an error() occurs it probably
         means further attempts to backtrace would fail (on the other
         hand, perhaps the code does or could be fixed to make sure
         the frame->prev field gets set to NULL in that case).  */
      print_frame_info (fi, 1, LOCATION, 1);
      if (show_locals)
	print_frame_local_vars (fi, 1, gdb_stdout);

      /* Save the last frame to check for error conditions.  */
      trailing = fi;
    }

  /* If we've stopped before the end, mention that.  */
  if (fi && from_tty)
    printf_filtered (_("(More stack frames follow...)\n"));

  /* If we've run out of frames, and the reason appears to be an error
     condition, print it.  */
  if (fi == NULL && trailing != NULL)
    {
      enum unwind_stop_reason reason;

      reason = get_frame_unwind_stop_reason (trailing);
      if (reason > UNWIND_FIRST_ERROR)
	printf_filtered (_("Backtrace stopped: %s\n"),
			 frame_stop_reason_string (reason));
    }
}

struct backtrace_command_args
{
  char *count_exp;
  int show_locals;
  int from_tty;
};

/* Stub for catch_errors.  */

static int
backtrace_command_stub (void *data)
{
  struct backtrace_command_args *args = data;
  backtrace_command_1 (args->count_exp, args->show_locals, args->from_tty);
  return 0;
}

static void
backtrace_command (char *arg, int from_tty)
{
  struct cleanup *old_chain = NULL;
  int fulltrace_arg = -1, arglen = 0, argc = 0;
  struct backtrace_command_args btargs;

  if (arg)
    {
      char **argv;
      int i;

      argv = buildargv (arg);
      old_chain = make_cleanup_freeargv (argv);
      argc = 0;
      for (i = 0; argv[i]; i++)
	{
	  unsigned int j;

	  for (j = 0; j < strlen (argv[i]); j++)
	    argv[i][j] = tolower (argv[i][j]);

	  if (fulltrace_arg < 0 && subset_compare (argv[i], "full"))
	    fulltrace_arg = argc;
	  else
	    {
	      arglen += strlen (argv[i]);
	      argc++;
	    }
	}
      arglen += argc;
      if (fulltrace_arg >= 0)
	{
	  if (arglen > 0)
	    {
	      arg = xmalloc (arglen + 1);
	      memset (arg, 0, arglen + 1);
	      for (i = 0; i < (argc + 1); i++)
		{
		  if (i != fulltrace_arg)
		    {
		      strcat (arg, argv[i]);
		      strcat (arg, " ");
		    }
		}
	    }
	  else
	    arg = NULL;
	}
    }

  btargs.count_exp = arg;
  btargs.show_locals = (fulltrace_arg >= 0);
  btargs.from_tty = from_tty;
  catch_errors (backtrace_command_stub, &btargs, "", RETURN_MASK_ERROR);

  if (fulltrace_arg >= 0 && arglen > 0)
    xfree (arg);

  if (old_chain)
    do_cleanups (old_chain);
}

static void
backtrace_full_command (char *arg, int from_tty)
{
  struct backtrace_command_args btargs;
  btargs.count_exp = arg;
  btargs.show_locals = 1;
  btargs.from_tty = from_tty;
  catch_errors (backtrace_command_stub, &btargs, "", RETURN_MASK_ERROR);
}


/* Print the local variables of a block B active in FRAME on STREAM.
   Return 1 if any variables were printed; 0 otherwise.  */

static int
print_block_frame_locals (struct block *b, struct frame_info *frame,
			  int num_tabs, struct ui_file *stream)
{
  struct dict_iterator iter;
  struct symbol *sym;
  int values_printed = 0;
  int j;

  ALL_BLOCK_SYMBOLS (b, iter, sym)
    {
      switch (SYMBOL_CLASS (sym))
	{
	case LOC_LOCAL:
	case LOC_REGISTER:
	case LOC_STATIC:
	case LOC_BASEREG:
	case LOC_COMPUTED:
	  values_printed = 1;
	  for (j = 0; j < num_tabs; j++)
	    fputs_filtered ("\t", stream);
	  fputs_filtered (SYMBOL_PRINT_NAME (sym), stream);
	  fputs_filtered (" = ", stream);
	  print_variable_value (sym, frame, stream);
	  fprintf_filtered (stream, "\n");
	  break;

	default:
	  /* Ignore symbols which are not locals.  */
	  break;
	}
    }

  return values_printed;
}

/* Same, but print labels.  */

static int
print_block_frame_labels (struct block *b, int *have_default,
			  struct ui_file *stream)
{
  struct dict_iterator iter;
  struct symbol *sym;
  int values_printed = 0;

  ALL_BLOCK_SYMBOLS (b, iter, sym)
    {
      if (strcmp (DEPRECATED_SYMBOL_NAME (sym), "default") == 0)
	{
	  if (*have_default)
	    continue;
	  *have_default = 1;
	}
      if (SYMBOL_CLASS (sym) == LOC_LABEL)
	{
	  struct symtab_and_line sal;
	  sal = find_pc_line (SYMBOL_VALUE_ADDRESS (sym), 0);
	  values_printed = 1;
	  fputs_filtered (SYMBOL_PRINT_NAME (sym), stream);
	  if (addressprint)
	    {
	      fprintf_filtered (stream, " ");
	      deprecated_print_address_numeric (SYMBOL_VALUE_ADDRESS (sym), 1, stream);
	    }
	  fprintf_filtered (stream, " in file %s, line %d\n",
			    sal.symtab->filename, sal.line);
	}
    }

  return values_printed;
}

/* Print on STREAM all the local variables in frame FRAME, including
   all the blocks active in that frame at its current PC.

   Returns 1 if the job was done, or 0 if nothing was printed because
   we have no info on the function running in FRAME.  */

static void
print_frame_local_vars (struct frame_info *frame, int num_tabs,
			struct ui_file *stream)
{
  struct block *block = get_frame_block (frame, 0);
  int values_printed = 0;

  if (block == 0)
    {
      fprintf_filtered (stream, "No symbol table info available.\n");
      return;
    }

  while (block)
    {
      if (print_block_frame_locals (block, frame, num_tabs, stream))
	values_printed = 1;
      /* After handling the function's top-level block, stop.  Don't
         continue to its superblock, the block of per-file symbols.  */
      if (BLOCK_FUNCTION (block))
	break;
      block = BLOCK_SUPERBLOCK (block);
    }

  if (!values_printed)
    fprintf_filtered (stream, _("No locals.\n"));
}

/* Same, but print labels.  */

static void
print_frame_label_vars (struct frame_info *frame, int this_level_only,
			struct ui_file *stream)
{
  struct blockvector *bl;
  struct block *block = get_frame_block (frame, 0);
  int values_printed = 0;
  int index, have_default = 0;
  char *blocks_printed;
  CORE_ADDR pc = get_frame_pc (frame);

  if (block == 0)
    {
      fprintf_filtered (stream, "No symbol table info available.\n");
      return;
    }

  bl = blockvector_for_pc (BLOCK_END (block) - 4, &index);
  blocks_printed = alloca (BLOCKVECTOR_NBLOCKS (bl) * sizeof (char));
  memset (blocks_printed, 0, BLOCKVECTOR_NBLOCKS (bl) * sizeof (char));

  while (block != 0)
    {
      CORE_ADDR end = BLOCK_END (block) - 4;
      int last_index;

      if (bl != blockvector_for_pc (end, &index))
	error (_("blockvector blotch"));
      if (BLOCKVECTOR_BLOCK (bl, index) != block)
	error (_("blockvector botch"));
      last_index = BLOCKVECTOR_NBLOCKS (bl);
      index += 1;

      /* Don't print out blocks that have gone by.  */
      while (index < last_index
	     && BLOCK_END (BLOCKVECTOR_BLOCK (bl, index)) < pc)
	index++;

      while (index < last_index
	     && BLOCK_END (BLOCKVECTOR_BLOCK (bl, index)) < end)
	{
	  if (blocks_printed[index] == 0)
	    {
	      if (print_block_frame_labels (BLOCKVECTOR_BLOCK (bl, index),
					    &have_default, stream))
		values_printed = 1;
	      blocks_printed[index] = 1;
	    }
	  index++;
	}
      if (have_default)
	return;
      if (values_printed && this_level_only)
	return;

      /* After handling the function's top-level block, stop.  Don't
         continue to its superblock, the block of per-file symbols.  */
      if (BLOCK_FUNCTION (block))
	break;
      block = BLOCK_SUPERBLOCK (block);
    }

  if (!values_printed && !this_level_only)
    fprintf_filtered (stream, _("No catches.\n"));
}

void
locals_info (char *args, int from_tty)
{
  print_frame_local_vars (get_selected_frame (_("No frame selected.")),
			  0, gdb_stdout);
}

static void
catch_info (char *ignore, int from_tty)
{
  struct symtab_and_line *sal;

  /* Check for target support for exception handling */
  sal = target_enable_exception_callback (EX_EVENT_CATCH, 1);
  if (sal)
    {
      /* Currently not handling this.  Ideally, here we should
         interact with the C++ runtime system to find the list of
         active handlers, etc.  */
      fprintf_filtered (gdb_stdout, _("\
Info catch not supported with this target/compiler combination.\n"));
    }
  else
    {
      /* Assume g++ compiled code; old GDB 4.16 behaviour.  */
      print_frame_label_vars (get_selected_frame (_("No frame selected.")),
			      0, gdb_stdout);
    }
}

static void
print_frame_arg_vars (struct frame_info *frame, struct ui_file *stream)
{
  struct symbol *func = get_frame_function (frame);
  struct block *b;
  struct dict_iterator iter;
  struct symbol *sym, *sym2;
  int values_printed = 0;

  if (func == 0)
    {
      fprintf_filtered (stream, _("No symbol table info available.\n"));
      return;
    }

  b = SYMBOL_BLOCK_VALUE (func);
  ALL_BLOCK_SYMBOLS (b, iter, sym)
    {
      switch (SYMBOL_CLASS (sym))
	{
	case LOC_ARG:
	case LOC_LOCAL_ARG:
	case LOC_REF_ARG:
	case LOC_REGPARM:
	case LOC_REGPARM_ADDR:
	case LOC_BASEREG_ARG:
	case LOC_COMPUTED_ARG:
	  values_printed = 1;
	  fputs_filtered (SYMBOL_PRINT_NAME (sym), stream);
	  fputs_filtered (" = ", stream);

	  /* We have to look up the symbol because arguments can have
	     two entries (one a parameter, one a local) and the one we
	     want is the local, which lookup_symbol will find for us.
	     This includes gcc1 (not gcc2) on the sparc when passing a
	     small structure and gcc2 when the argument type is float
	     and it is passed as a double and converted to float by
	     the prologue (in the latter case the type of the LOC_ARG
	     symbol is double and the type of the LOC_LOCAL symbol is
	     float).  There are also LOC_ARG/LOC_REGISTER pairs which
	     are not combined in symbol-reading.  */

	  sym2 = lookup_symbol (DEPRECATED_SYMBOL_NAME (sym),
				b, VAR_DOMAIN, NULL, NULL);
	  print_variable_value (sym2, frame, stream);
	  fprintf_filtered (stream, "\n");
	  break;

	default:
	  /* Don't worry about things which aren't arguments.  */
	  break;
	}
    }

  if (!values_printed)
    fprintf_filtered (stream, _("No arguments.\n"));
}

void
args_info (char *ignore, int from_tty)
{
  print_frame_arg_vars (get_selected_frame (_("No frame selected.")),
			gdb_stdout);
}


static void
args_plus_locals_info (char *ignore, int from_tty)
{
  args_info (ignore, from_tty);
  locals_info (ignore, from_tty);
}


/* Select frame FRAME.  Also print the stack frame and show the source
   if this is the tui version.  */
static void
select_and_print_frame (struct frame_info *frame)
{
  select_frame (frame);
  if (frame)
    print_stack_frame (frame, 1, SRC_AND_LOC);
}

/* Return the symbol-block in which the selected frame is executing.
   Can return zero under various legitimate circumstances.

   If ADDR_IN_BLOCK is non-zero, set *ADDR_IN_BLOCK to the relevant
   code address within the block returned.  We use this to decide
   which macros are in scope.  */

struct block *
get_selected_block (CORE_ADDR *addr_in_block)
{
  if (!target_has_stack)
    return 0;

  return get_frame_block (get_selected_frame (NULL), addr_in_block);
}

/* Find a frame a certain number of levels away from FRAME.
   LEVEL_OFFSET_PTR points to an int containing the number of levels.
   Positive means go to earlier frames (up); negative, the reverse.
   The int that contains the number of levels is counted toward
   zero as the frames for those levels are found.
   If the top or bottom frame is reached, that frame is returned,
   but the final value of *LEVEL_OFFSET_PTR is nonzero and indicates
   how much farther the original request asked to go.  */

struct frame_info *
find_relative_frame (struct frame_info *frame, int *level_offset_ptr)
{
  /* Going up is simple: just call get_prev_frame enough times or
     until the initial frame is reached.  */
  while (*level_offset_ptr > 0)
    {
      struct frame_info *prev = get_prev_frame (frame);
      if (!prev)
	break;
      (*level_offset_ptr)--;
      frame = prev;
    }

  /* Going down is just as simple.  */
  while (*level_offset_ptr < 0)
    {
      struct frame_info *next = get_next_frame (frame);
      if (!next)
	break;
      (*level_offset_ptr)++;
      frame = next;
    }

  return frame;
}

/* The "select_frame" command.  With no argument this is a NOP.
   Select the frame at level LEVEL_EXP if it is a valid level.
   Otherwise, treat LEVEL_EXP as an address expression and select it.

   See parse_frame_specification for more info on proper frame
   expressions.  */

void
select_frame_command (char *level_exp, int from_tty)
{
  select_frame (parse_frame_specification_1 (level_exp, "No stack.", NULL));
}

/* The "frame" command.  With no argument, print the selected frame
   briefly.  With an argument, behave like select_frame and then print
   the selected frame.  */

static void
frame_command (char *level_exp, int from_tty)
{
  select_frame_command (level_exp, from_tty);
  print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
}

/* The XDB Compatibility command to print the current frame.  */

static void
current_frame_command (char *level_exp, int from_tty)
{
  print_stack_frame (get_selected_frame (_("No stack.")), 1, SRC_AND_LOC);
}

/* Select the frame up one or COUNT_EXP stack levels from the
   previously selected frame, and print it briefly.  */

static void
up_silently_base (char *count_exp)
{
  struct frame_info *frame;
  int count = 1;

  if (count_exp)
    count = parse_and_eval_long (count_exp);

  frame = find_relative_frame (get_selected_frame ("No stack."), &count);
  if (count != 0 && count_exp == NULL)
    error (_("Initial frame selected; you cannot go up."));
  select_frame (frame);
}

static void
up_silently_command (char *count_exp, int from_tty)
{
  up_silently_base (count_exp);
}

static void
up_command (char *count_exp, int from_tty)
{
  up_silently_base (count_exp);
  print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
}

/* Select the frame down one or COUNT_EXP stack levels from the previously
   selected frame, and print it briefly.  */

static void
down_silently_base (char *count_exp)
{
  struct frame_info *frame;
  int count = -1;
  if (count_exp)
    count = -parse_and_eval_long (count_exp);

  frame = find_relative_frame (get_selected_frame ("No stack."), &count);
  if (count != 0 && count_exp == NULL)
    {
      /* We only do this if COUNT_EXP is not specified.  That way
         "down" means to really go down (and let me know if that is
         impossible), but "down 9999" can be used to mean go all the
         way down without getting an error.  */

      error (_("Bottom (innermost) frame selected; you cannot go down."));
    }

  select_frame (frame);
}

static void
down_silently_command (char *count_exp, int from_tty)
{
  down_silently_base (count_exp);
}

static void
down_command (char *count_exp, int from_tty)
{
  down_silently_base (count_exp);
  print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
}


void
return_command (char *retval_exp, int from_tty)
{
  struct symbol *thisfun;
  struct value *return_value = NULL;
  const char *query_prefix = "";

  thisfun = get_frame_function (get_selected_frame ("No selected frame."));

  /* Compute the return value.  If the computation triggers an error,
     let it bail.  If the return type can't be handled, set
     RETURN_VALUE to NULL, and QUERY_PREFIX to an informational
     message.  */
  if (retval_exp)
    {
      struct type *return_type = NULL;

      /* Compute the return value.  Should the computation fail, this
         call throws an error.  */
      return_value = parse_and_eval (retval_exp);

      /* Cast return value to the return type of the function.  Should
         the cast fail, this call throws an error.  */
      if (thisfun != NULL)
	return_type = TYPE_TARGET_TYPE (SYMBOL_TYPE (thisfun));
      if (return_type == NULL)
	return_type = builtin_type_int;
      CHECK_TYPEDEF (return_type);
      return_value = value_cast (return_type, return_value);

      /* Make sure the value is fully evaluated.  It may live in the
         stack frame we're about to pop.  */
      if (value_lazy (return_value))
	value_fetch_lazy (return_value);

      if (TYPE_CODE (return_type) == TYPE_CODE_VOID)
	/* If the return-type is "void", don't try to find the
           return-value's location.  However, do still evaluate the
           return expression so that, even when the expression result
           is discarded, side effects such as "return i++" still
           occur.  */
	return_value = NULL;
      /* FIXME: cagney/2004-01-17: If the architecture implements both
         return_value and extract_returned_value_address, should allow
         "return" to work - don't set return_value to NULL.  */
      else if (!gdbarch_return_value_p (current_gdbarch)
	       && (TYPE_CODE (return_type) == TYPE_CODE_STRUCT
		   || TYPE_CODE (return_type) == TYPE_CODE_UNION))
	{
	  /* NOTE: cagney/2003-10-20: Compatibility hack for legacy
	     code.  Old architectures don't expect STORE_RETURN_VALUE
	     to be called with with a small struct that needs to be
	     stored in registers.  Don't start doing it now.  */
	  query_prefix = "\
A structure or union return type is not supported by this architecture.\n\
If you continue, the return value that you specified will be ignored.\n";
	  return_value = NULL;
	}
      else if (using_struct_return (return_type, 0))
	{
	  query_prefix = "\
The location at which to store the function's return value is unknown.\n\
If you continue, the return value that you specified will be ignored.\n";
	  return_value = NULL;
	}
    }

  /* Does an interactive user really want to do this?  Include
     information, such as how well GDB can handle the return value, in
     the query message.  */
  if (from_tty)
    {
      int confirmed;
      if (thisfun == NULL)
	confirmed = query (_("%sMake selected stack frame return now? "),
			   query_prefix);
      else
	confirmed = query (_("%sMake %s return now? "), query_prefix,
			   SYMBOL_PRINT_NAME (thisfun));
      if (!confirmed)
	error (_("Not confirmed"));
    }

  /* NOTE: cagney/2003-01-18: Is this silly?  Rather than pop each
     frame in turn, should this code just go straight to the relevant
     frame and pop that?  */

  /* First discard all frames inner-to the selected frame (making the
     selected frame current).  */
  {
    struct frame_id selected_id = get_frame_id (get_selected_frame (NULL));
    while (!frame_id_eq (selected_id, get_frame_id (get_current_frame ())))
      {
	if (frame_id_inner (selected_id, get_frame_id (get_current_frame ())))
	  /* Caught in the safety net, oops!  We've gone way past the
             selected frame.  */
	  error (_("Problem while popping stack frames (corrupt stack?)"));
	frame_pop (get_current_frame ());
      }
  }

  /* Second discard the selected frame (which is now also the current
     frame).  */
  frame_pop (get_current_frame ());

  /* Store RETURN_VALUE in the just-returned register set.  */
  if (return_value != NULL)
    {
      struct type *return_type = value_type (return_value);
      gdb_assert (gdbarch_return_value (current_gdbarch, return_type,
					NULL, NULL, NULL)
		  == RETURN_VALUE_REGISTER_CONVENTION);
      gdbarch_return_value (current_gdbarch, return_type,
			    current_regcache, NULL /*read*/,
			    value_contents (return_value) /*write*/);
    }

  /* If we are at the end of a call dummy now, pop the dummy frame
     too.  */
  if (get_frame_type (get_current_frame ()) == DUMMY_FRAME)
    frame_pop (get_current_frame ());

  /* If interactive, print the frame that is now current.  */
  if (from_tty)
    frame_command ("0", 1);
  else
    select_frame_command ("0", 0);
}

/* Sets the scope to input function name, provided that the function
   is within the current stack frame */

struct function_bounds
{
  CORE_ADDR low, high;
};

static void
func_command (char *arg, int from_tty)
{
  struct frame_info *frame;
  int found = 0;
  struct symtabs_and_lines sals;
  int i;
  int level = 1;
  struct function_bounds *func_bounds = NULL;

  if (arg != NULL)
    return;

  frame = parse_frame_specification ("0");
  sals = decode_line_spec (arg, 1);
  func_bounds = (struct function_bounds *) xmalloc (
			      sizeof (struct function_bounds) * sals.nelts);
  for (i = 0; (i < sals.nelts && !found); i++)
    {
      if (sals.sals[i].pc == 0
	  || find_pc_partial_function (sals.sals[i].pc, NULL,
				       &func_bounds[i].low,
				       &func_bounds[i].high) == 0)
	{
	  func_bounds[i].low = func_bounds[i].high = 0;
	}
    }

  do
    {
      for (i = 0; (i < sals.nelts && !found); i++)
	found = (get_frame_pc (frame) >= func_bounds[i].low
		 && get_frame_pc (frame) < func_bounds[i].high);
      if (!found)
	{
	  level = 1;
	  frame = find_relative_frame (frame, &level);
	}
    }
  while (!found && level == 0);

  if (func_bounds)
    xfree (func_bounds);

  if (!found)
    printf_filtered (_("'%s' not within current stack frame.\n"), arg);
  else if (frame != get_selected_frame (NULL))
    select_and_print_frame (frame);
}

/* Gets the language of the current frame.  */

enum language
get_frame_language (void)
{
  struct frame_info *frame = deprecated_safe_get_selected_frame ();

  if (frame)
    {
      /* We determine the current frame language by looking up its
         associated symtab.  To retrieve this symtab, we use the frame
         PC.  However we cannot use the frame PC as is, because it
         usually points to the instruction following the "call", which
         is sometimes the first instruction of another function.  So
         we rely on get_frame_address_in_block(), it provides us with
         a PC that is guaranteed to be inside the frame's code
         block.  */
      CORE_ADDR pc = get_frame_address_in_block (frame);
      struct symtab *s = find_pc_symtab (pc);

      if (s)
	return s->language;
    }

  return language_unknown;
}


/* Provide a prototype to silence -Wmissing-prototypes.  */
void _initialize_stack (void);

void
_initialize_stack (void)
{
#if 0
  backtrace_limit = 30;
#endif

  add_com ("return", class_stack, return_command, _("\
Make selected stack frame return to its caller.\n\
Control remains in the debugger, but when you continue\n\
execution will resume in the frame above the one now selected.\n\
If an argument is given, it is an expression for the value to return."));

  add_com ("up", class_stack, up_command, _("\
Select and print stack frame that called this one.\n\
An argument says how many frames up to go."));
  add_com ("up-silently", class_support, up_silently_command, _("\
Same as the `up' command, but does not print anything.\n\
This is useful in command scripts."));

  add_com ("down", class_stack, down_command, _("\
Select and print stack frame called by this one.\n\
An argument says how many frames down to go."));
  add_com_alias ("do", "down", class_stack, 1);
  add_com_alias ("dow", "down", class_stack, 1);
  add_com ("down-silently", class_support, down_silently_command, _("\
Same as the `down' command, but does not print anything.\n\
This is useful in command scripts."));

  add_com ("frame", class_stack, frame_command, _("\
Select and print a stack frame.\n\
With no argument, print the selected stack frame.  (See also \"info frame\").\n\
An argument specifies the frame to select.\n\
It can be a stack frame number or the address of the frame.\n\
With argument, nothing is printed if input is coming from\n\
a command file or a user-defined command."));

  add_com_alias ("f", "frame", class_stack, 1);

  if (xdb_commands)
    {
      add_com ("L", class_stack, current_frame_command,
	       _("Print the current stack frame.\n"));
      add_com_alias ("V", "frame", class_stack, 1);
    }
  add_com ("select-frame", class_stack, select_frame_command, _("\
Select a stack frame without printing anything.\n\
An argument specifies the frame to select.\n\
It can be a stack frame number or the address of the frame.\n"));

  add_com ("backtrace", class_stack, backtrace_command, _("\
Print backtrace of all stack frames, or innermost COUNT frames.\n\
With a negative argument, print outermost -COUNT frames.\n\
Use of the 'full' qualifier also prints the values of the local variables.\n"));
  add_com_alias ("bt", "backtrace", class_stack, 0);
  if (xdb_commands)
    {
      add_com_alias ("t", "backtrace", class_stack, 0);
      add_com ("T", class_stack, backtrace_full_command, _("\
Print backtrace of all stack frames, or innermost COUNT frames \n\
and the values of the local variables.\n\
With a negative argument, print outermost -COUNT frames.\n\
Usage: T <count>\n"));
    }

  add_com_alias ("where", "backtrace", class_alias, 0);
  add_info ("stack", backtrace_command,
	    _("Backtrace of the stack, or innermost COUNT frames."));
  add_info_alias ("s", "stack", 1);
  add_info ("frame", frame_info,
	    _("All about selected stack frame, or frame at ADDR."));
  add_info_alias ("f", "frame", 1);
  add_info ("locals", locals_info,
	    _("Local variables of current stack frame."));
  add_info ("args", args_info,
	    _("Argument variables of current stack frame."));
  if (xdb_commands)
    add_com ("l", class_info, args_plus_locals_info,
	     _("Argument and local variables of current stack frame."));

  if (dbx_commands)
    add_com ("func", class_stack, func_command, _("\
Select the stack frame that contains <func>.\n\
Usage: func <name>\n"));

  add_info ("catch", catch_info,
	    _("Exceptions that can be caught in the current stack frame."));

#if 0
  add_cmd ("backtrace-limit", class_stack, set_backtrace_limit_command, _(\
"Specify maximum number of frames for \"backtrace\" to print by default."),
	   &setlist);
  add_info ("backtrace-limit", backtrace_limit_info, _("\
The maximum number of frames for \"backtrace\" to print by default."));
#endif
}