xref: /openbsd-current/gnu/usr.bin/binutils/gdb/stack.c

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

   Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
   1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <ctype.h>
#include "defs.h"
#include "gdb_string.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 "gdb_assert.h"
#include "dictionary.h"
#include "reggroups.h"
#include "regcache.h"

/* Prototypes for exported functions. */

void args_info (char *, int);

void locals_info (char *, int);

void (*selected_frame_level_changed_hook) (int);

void _initialize_stack (void);

/* Prototypes for local functions. */

static void down_command (char *, int);

static void down_silently_base (char *);

static void down_silently_command (char *, int);

static void up_command (char *, int);

static void up_silently_base (char *);

static void up_silently_command (char *, int);

void frame_command (char *, int);

static void current_frame_command (char *, int);

static void print_frame_arg_vars (struct frame_info *, struct ui_file *);

static void catch_info (char *, int);

static void args_plus_locals_info (char *, int);

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

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

static int print_block_frame_labels (struct block *, int *,
				     struct ui_file *);

static int print_block_frame_locals (struct block *,
				     struct frame_info *,
				     int,
				     struct ui_file *);

static void print_frame (struct frame_info *fi,
			 int level,
			 int source,
			 int args,
			 struct symtab_and_line sal);

static void backtrace_command (char *, int);

struct frame_info *parse_frame_specification (char *);

static void frame_info (char *, int);

extern int addressprint;	/* Print addresses, or stay symbolic only? */

/* 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 *fi;
    int level;
    int source;
    int args;
  };

/* Show or print the frame arguments.
   Pass the args the way catch_errors wants them.  */
static int print_stack_frame_stub (void *args);
static int
print_stack_frame_stub (void *args)
{
  struct print_stack_frame_args *p = (struct print_stack_frame_args *) args;

  print_frame_info (p->fi, p->level, p->source, p->args);
  return 0;
}

/* Show or print a stack frame briefly.  FRAME_INFI should be the frame info
   and LEVEL should be its level in the stack (or -1 for level not defined).
   This prints the level, the function executing, the arguments,
   and the file name and line number.
   If the pc is not at the beginning of the source line,
   the actual pc is printed at the beginning.

   If SOURCE is 1, print the source line as well.
   If SOURCE is -1, print ONLY the source line.  */

void
print_stack_frame (struct frame_info *fi, int level, int source)
{
  struct print_stack_frame_args args;

  args.fi = fi;
  args.level = level;
  args.source = source;
  args.args = 1;

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

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

static int print_args_stub (void *);

/* Print nameless args on STREAM.
   FI is the frameinfo for this frame, START is the offset
   of the first nameless arg, and NUM is the number of nameless args to
   print.  FIRST is nonzero if this is the first argument (not just
   the first nameless arg).  */

static void
print_frame_nameless_args (struct frame_info *fi, 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 (fi);
      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 a stack frame, given the function FUNC
   running in that frame (as a symbol), the info on the frame,
   and the number of args according to the stack frame (or -1 if unknown).  */

/* References here and elsewhere to "number of args according to the
   stack frame" appear in all cases to refer to "number of ints of args
   according to the stack frame".  At least for VAX, i386, isi.  */

static void
print_frame_args (struct symbol *func, struct frame_info *fi, int num,
		  struct ui_file *stream)
{
  struct block *b = NULL;
  int first = 1;
  struct dict_iterator iter;
  struct symbol *sym;
  struct value *val;
  /* Offset of next stack argument beyond the one we have seen that is
     at the highest offset.
     -1 if we haven't come to a stack argument yet.  */
  long highest_offset = -1;
  int arg_size;
  /* 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)
    {
      b = SYMBOL_BLOCK_VALUE (func);

      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);
		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 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).  */
	  /* 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, (int *) NULL, (struct symtab **) 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, fi);

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

	  if (val)
	    {
	      val_print (VALUE_TYPE (val), VALUE_CONTENTS (val), 0,
			 VALUE_ADDRESS (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 = FRAME_ARGS_SKIP;
      else
	start = highest_offset;

      print_frame_nameless_args (fi, start, num - args_printed,
				 first, stream);
    }
  do_cleanups (old_chain);
}

/* Pass the args the way catch_errors wants them.  */

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

  if (FRAME_NUM_ARGS_P ())
    {
      numargs = FRAME_NUM_ARGS (p->fi);
      gdb_assert (numargs >= 0);
    }
  else
    numargs = -1;
  print_frame_args (p->func, p->fi, numargs, p->stream);
  return 0;
}

/* Print information about a frame for frame "fi" at level "level".
   Used in "where" output, also used to emit breakpoint or step
   messages.
   LEVEL is the level of the frame, or -1 if it is the
   innermost frame but we don't want to print the level.
   The meaning of the SOURCE argument is:
   SRC_LINE: Print only source line
   LOCATION: Print only location
   LOC_AND_SRC: Print location and source line.  */

void
print_frame_info (struct frame_info *fi, int level, int source, int args)
{
  struct symtab_and_line sal;
  int source_print;
  int location_print;

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

      annotate_frame_begin (level == -1 ? 0 : level, get_frame_pc (fi));

      /* Do this regardless of SOURCE because we don't have any source
         to list for this frame.  */
      if (level >= 0)
        {
          ui_out_text (uiout, "#");
          ui_out_field_fmt_int (uiout, 2, ui_left, "level", level);
        }
      if (ui_out_is_mi_like_p (uiout))
        {
          annotate_frame_address ();
          ui_out_field_core_addr (uiout, "addr", get_frame_pc (fi));
          annotate_frame_address_end ();
        }

      if (get_frame_type (fi) == DUMMY_FRAME)
        {
          annotate_function_call ();
          ui_out_field_string (uiout, "func", "<function called from gdb>");
	}
      else if (get_frame_type (fi) == 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 fi is not the innermost frame, that normally means that fi->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 fi->pc.  */
  find_frame_sal (fi, &sal);

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

  if (location_print || !sal.symtab)
    print_frame (fi, level, source, args, sal);

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

  if (sal.symtab)
    set_current_source_symtab_and_line (&sal);

  if (source_print && sal.symtab)
    {
      struct symtab_and_line cursal;
      int done = 0;
      int mid_statement = (source == SRC_LINE) && (get_frame_pc (fi) != sal.pc);

      if (annotation_level)
	done = identify_source_line (sal.symtab, sal.line, mid_statement,
				     get_frame_pc (fi));
      if (!done)
	{
	  if (print_frame_info_listing_hook)
	    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 (fi));
		  ui_out_text (uiout, "\t");
		}

	      print_source_lines (sal.symtab, sal.line, sal.line + 1, 0);
	    }
	}
      /* Make sure we have at least a default source file */
      set_default_source_symtab_and_line ();
      cursal = get_current_source_symtab_and_line ();
      cursal.line = max (sal.line - get_lines_to_list () / 2, 1);
      set_current_source_symtab_and_line (&cursal);
    }

  if (source != 0)
    set_default_breakpoint (1, get_frame_pc (fi), sal.symtab, sal.line);

  annotate_frame_end ();

  gdb_flush (gdb_stdout);
}

static void
print_frame (struct frame_info *fi,
	     int level,
	     int source,
	     int args,
	     struct symtab_and_line sal)
{
  struct symbol *func;
  char *funname = 0;
  enum language funlang = language_unknown;
  struct ui_stream *stb;
  struct cleanup *old_chain;
  struct cleanup *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 (fi));
  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 -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 (fi));
      if (msymbol != NULL
	  && (SYMBOL_VALUE_ADDRESS (msymbol)
	      > BLOCK_START (SYMBOL_BLOCK_VALUE (func))))
	{
#if 0
	  /* There is no particular reason to think the line number
	     information is wrong.  Someone might have just put in
	     a label with asm() but left the line numbers alone.  */
	  /* In this case we have no way of knowing the source file
	     and line number, so don't print them.  */
	  sal.symtab = 0;
#endif
	  /* 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
	{
	  /* I'd like 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, I know
	     that printf_symbol_filtered() will again try to demangle
	     the name on the fly, but the issue is that if
	     cplus_demangle() fails here, it'll fail there too. So we
	     want to catch the failure ("demangled==NULL" case below)
	     here, while we still have our hands on the function
	     symbol.) */
	  char *demangled;
	  funname = DEPRECATED_SYMBOL_NAME (func);
	  funlang = SYMBOL_LANGUAGE (func);
	  if (funlang == language_cplus)
	    {
	      demangled = cplus_demangle (funname, DMGL_ANSI);
	      if (demangled == NULL)
		/* If the demangler fails, try the demangled name from
		   the symbol table. This'll have parameters, but
		   that's preferable to diplaying a mangled name. */
		funname = SYMBOL_PRINT_NAME (func);
	    }
	}
    }
  else
    {
      struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (get_frame_address_in_block (fi));
      if (msymbol != NULL)
	{
	  funname = DEPRECATED_SYMBOL_NAME (msymbol);
	  funlang = SYMBOL_LANGUAGE (msymbol);
	}
    }

  annotate_frame_begin (level == -1 ? 0 : level, get_frame_pc (fi));

  list_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "frame");

  if (level >= 0)
    {
      ui_out_text (uiout, "#");
      ui_out_field_fmt_int (uiout, 2, ui_left, "level", level);
    }
  if (addressprint)
    if (get_frame_pc (fi) != sal.pc
	|| !sal.symtab
	|| source == LOC_AND_ADDRESS)
      {
	annotate_frame_address ();
	ui_out_field_core_addr (uiout, "addr", get_frame_pc (fi));
	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 (args)
    {
      struct print_args_args args;
      struct cleanup *args_list_chain;
      args.fi = fi;
      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);
      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 ();
    }

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

  /* 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 *fi)
{
}


/* Read a frame specification in whatever the appropriate format is.
   Call error() if the specification is in any way invalid (i.e.
   this function never returns NULL).  */

struct frame_info *
parse_frame_specification (char *frame_exp)
{
  int numargs = 0;
#define	MAXARGS	4
  CORE_ADDR args[MAXARGS];
  int level;

  if (frame_exp)
    {
      char *addr_string, *p;
      struct cleanup *tmp_cleanup;

      while (*frame_exp == ' ')
	frame_exp++;

      while (*frame_exp)
	{
	  if (numargs > MAXARGS)
	    error ("Too many args in frame specification");
	  /* Parse an argument.  */
	  for (p = frame_exp; *p && *p != ' '; p++)
	    ;
	  addr_string = savestring (frame_exp, p - frame_exp);

	  {
	    struct value *vp;

	    tmp_cleanup = make_cleanup (xfree, addr_string);

	    /* NOTE: we call parse_and_eval and then both
	       value_as_long and value_as_address rather than calling
	       parse_and_eval_long and parse_and_eval_address because
	       of the issue of potential side effects from evaluating
	       the expression.  */
	    vp = parse_and_eval (addr_string);
	    if (numargs == 0)
	      level = value_as_long (vp);

	    args[numargs++] = value_as_address (vp);
	    do_cleanups (tmp_cleanup);
	  }

	  /* Skip spaces, move to possible next arg.  */
	  while (*p == ' ')
	    p++;
	  frame_exp = p;
	}
    }

  switch (numargs)
    {
    case 0:
      if (deprecated_selected_frame == NULL)
	error ("No selected frame.");
      return deprecated_selected_frame;
      /* NOTREACHED */
    case 1:
      {
	struct frame_info *fid =
	find_relative_frame (get_current_frame (), &level);
	struct frame_info *tfid;

	if (level == 0)
	  /* find_relative_frame was successful */
	  return fid;

	/* If SETUP_ARBITRARY_FRAME is defined, then frame specifications
	   take at least 2 addresses.  It is important to detect this case
	   here so that "frame 100" does not give a confusing error message
	   like "frame specification requires two addresses".  This of course
	   does not solve the "frame 100" problem for machines on which
	   a frame specification can be made with one address.  To solve
	   that, we need a new syntax for a specifying a frame by address.
	   I think the cleanest syntax is $frame(0x45) ($frame(0x23,0x45) for
	   two args, etc.), but people might think that is too much typing,
	   so I guess *0x23,0x45 would be a possible alternative (commas
	   really should be used instead of spaces to delimit; using spaces
	   normally works in an expression).  */
#ifdef SETUP_ARBITRARY_FRAME
	error ("No frame %s", paddr_d (args[0]));
#endif

	/* If (s)he specifies the frame with an address, he deserves what
	   (s)he gets.  Still, give the highest one that matches.  */

	for (fid = get_current_frame ();
	     fid && get_frame_base (fid) != args[0];
	     fid = get_prev_frame (fid))
	  ;

	if (fid)
	  while ((tfid = get_prev_frame (fid)) &&
		 (get_frame_base (tfid) == args[0]))
	    fid = tfid;

	/* We couldn't identify the frame as an existing frame, but
	   perhaps we can create one with a single argument.  */
      }

    default:
#ifdef SETUP_ARBITRARY_FRAME
      return SETUP_ARBITRARY_FRAME (numargs, args);
#else
      /* Usual case.  Do it here rather than have everyone supply
         a SETUP_ARBITRARY_FRAME that does this.  */
      if (numargs == 1)
	return create_new_frame (args[0], 0);
      error ("Too many args in frame specification");
#endif
      /* NOTREACHED */
    }
  /* NOTREACHED */
}

/* Print verbosely the selected frame or the frame at address ADDR.
   This means 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;

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

  /* 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 = REGISTER_NAME (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";

  fi = parse_frame_specification (addr_exp);
  if (fi == NULL)
    error ("Invalid frame specified.");

  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)
    {
      /* I'd like 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. RT
       * (Yes, I know that printf_symbol_filtered() will
       * again try to demangle the name on the fly, but
       * the issue is that if cplus_demangle() fails here,
       * it'll fail there too. So we want to catch the failure
       * ("demangled==NULL" case below) here, while we still
       * have our hands on the function symbol.)
       */
      char *demangled;
      funname = DEPRECATED_SYMBOL_NAME (func);
      funlang = SYMBOL_LANGUAGE (func);
      if (funlang == language_cplus)
	{
	  demangled = cplus_demangle (funname, DMGL_ANSI);
	  /* If the demangler fails, try the demangled name
	   * from the symbol table. This'll have parameters,
	   * but that's preferable to diplaying a mangled name.
	   */
	  if (demangled == NULL)
	    funname = SYMBOL_PRINT_NAME (func);
	}
    }
  else
    {
      struct minimal_symbol *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 (!addr_exp && frame_relative_level (deprecated_selected_frame) >= 0)
    {
      printf_filtered ("Stack level %d, frame at ",
		       frame_relative_level (deprecated_selected_frame));
      print_address_numeric (get_frame_base (fi), 1, gdb_stdout);
      printf_filtered (":\n");
    }
  else
    {
      printf_filtered ("Stack frame at ");
      print_address_numeric (get_frame_base (fi), 1, gdb_stdout);
      printf_filtered (":\n");
    }
  printf_filtered (" %s = ", pc_regname);
  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);
  print_address_numeric (frame_pc_unwind (fi), 1, gdb_stdout);
  printf_filtered ("\n");

  {
    int frameless;
    frameless = (DEPRECATED_FRAMELESS_FUNCTION_INVOCATION_P ()
		 && DEPRECATED_FRAMELESS_FUNCTION_INVOCATION (fi));
    if (frameless)
      printf_filtered (" (FRAMELESS),");
  }

  if (calling_frame_info)
    {
      printf_filtered (" called by frame at ");
      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 ");
      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 ");
	print_address_numeric (arg_list, 1, gdb_stdout);
	printf_filtered (",");

	if (!FRAME_NUM_ARGS_P ())
	  {
	    numargs = -1;
	    puts_filtered (" args: ");
	  }
	else
	  {
	    numargs = FRAME_NUM_ARGS (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 ");
	print_address_numeric (arg_list, 1, gdb_stdout);
	printf_filtered (",");
      }
  }

  if (DEPRECATED_FRAME_INIT_SAVED_REGS_P ()
      && deprecated_get_frame_saved_regs (fi) == NULL)
    DEPRECATED_FRAME_INIT_SAVED_REGS (fi);
  /* 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)
	  {
	    char 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, DEPRECATED_REGISTER_RAW_SIZE (SP_REGNUM));
	    printf_filtered (" Previous frame's sp is ");
	    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 ");
	    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",
			     REGISTER_NAME (realnum));
	    need_nl = 0;
	  }
	/* else keep quiet.  */
      }

    count = 0;
    numregs = NUM_REGS + NUM_PSEUDO_REGS;
    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 ", REGISTER_NAME (i));
	      print_address_numeric (addr, 1, gdb_stdout);
	      count++;
	    }
	}
    if (count || need_nl)
      puts_filtered ("\n");
  }
}

#if 0
/* Set a limit on the number of frames printed by default in a
   backtrace.  */

static int backtrace_limit;

static void
set_backtrace_limit_command (char *count_exp, int from_tty)
{
  int count = parse_and_eval_long (count_exp);

  if (count < 0)
    error ("Negative argument not meaningful as backtrace limit.");

  backtrace_limit = count;
}

static void
backtrace_limit_info (char *arg, int from_tty)
{
  if (arg)
    error ("\"Info backtrace-limit\" takes no arguments.");

  printf_unfiltered ("Backtrace limit: %d.\n", backtrace_limit);
}
#endif

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

static void backtrace_command_1 (char *count_exp, int show_locals,
				 int from_tty);
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, trailing_level + i, 0, 1);
      if (show_locals)
	print_frame_local_vars (fi, 1, gdb_stdout);
    }

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

static void
backtrace_command (char *arg, int from_tty)
{
  struct cleanup *old_chain = (struct cleanup *) NULL;
  char **argv = (char **) NULL;
  int argIndicatingFullTrace = (-1), totArgLen = 0, argc = 0;
  char *argPtr = arg;

  if (arg != (char *) NULL)
    {
      int i;

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

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

	  if (argIndicatingFullTrace < 0 && subset_compare (argv[i], "full"))
	    argIndicatingFullTrace = argc;
	  else
	    {
	      argc++;
	      totArgLen += strlen (argv[i]);
	    }
	}
      totArgLen += argc;
      if (argIndicatingFullTrace >= 0)
	{
	  if (totArgLen > 0)
	    {
	      argPtr = (char *) xmalloc (totArgLen + 1);
	      if (!argPtr)
		nomem (0);
	      else
		{
		  memset (argPtr, 0, totArgLen + 1);
		  for (i = 0; (i < (argc + 1)); i++)
		    {
		      if (i != argIndicatingFullTrace)
			{
			  strcat (argPtr, argv[i]);
			  strcat (argPtr, " ");
			}
		    }
		}
	    }
	  else
	    argPtr = (char *) NULL;
	}
    }

  backtrace_command_1 (argPtr, (argIndicatingFullTrace >= 0), from_tty);

  if (argIndicatingFullTrace >= 0 && totArgLen > 0)
    xfree (argPtr);

  if (old_chain)
    do_cleanups (old_chain);
}

static void backtrace_full_command (char *arg, int from_tty);
static void
backtrace_full_command (char *arg, int from_tty)
{
  backtrace_command_1 (arg, 1, from_tty);
}


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

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

  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, fi, 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 (DEPRECATED_STREQ (DEPRECATED_SYMBOL_NAME (sym), "default"))
	{
	  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, " ");
	      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 *fi, int num_tabs,
			struct ui_file *stream)
{
  struct block *block = get_frame_block (fi, 0);
  int values_printed = 0;

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

  while (block != 0)
    {
      if (print_block_frame_locals (block, fi, 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 *fi, int this_level_only,
			struct ui_file *stream)
{
  struct blockvector *bl;
  struct block *block = get_frame_block (fi, 0);
  int values_printed = 0;
  int index, have_default = 0;
  char *blocks_printed;
  CORE_ADDR pc = get_frame_pc (fi);

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

  bl = blockvector_for_pc (BLOCK_END (block) - 4, &index);
  blocks_printed = (char *) 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)
{
  if (!deprecated_selected_frame)
    error ("No frame selected.");
  print_frame_local_vars (deprecated_selected_frame, 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");
#if 0
      if (!deprecated_selected_frame)
	error ("No frame selected.");
#endif
    }
  else
    {
      /* Assume g++ compiled code -- old v 4.16 behaviour */
      if (!deprecated_selected_frame)
	error ("No frame selected.");

      print_frame_label_vars (deprecated_selected_frame, 0, gdb_stdout);
    }
}

static void
print_frame_arg_vars (struct frame_info *fi,
		      struct ui_file *stream)
{
  struct symbol *func = get_frame_function (fi);
  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, (int *) NULL, (struct symtab **) NULL);
	  print_variable_value (sym2, fi, 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)
{
  if (!deprecated_selected_frame)
    error ("No frame selected.");
  print_frame_arg_vars (deprecated_selected_frame, 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 FI.  Also print the stack frame and show the source if
   this is the tui version.  */
static void
select_and_print_frame (struct frame_info *fi)
{
  select_frame (fi);
  if (fi)
    {
      print_stack_frame (fi, frame_relative_level (fi), 1);
    }
}

/* 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;

  /* NOTE: cagney/2002-11-28: Why go to all this effort to not create
     a selected/current frame?  Perhaphs this function is called,
     indirectly, by WFI in "infrun.c" where avoiding the creation of
     an inner most frame is very important (it slows down single
     step).  I suspect, though that this was true in the deep dark
     past but is no longer the case.  A mindless look at all the
     callers tends to support this theory.  I think we should be able
     to assume that there is always a selcted frame.  */
  /* gdb_assert (deprecated_selected_frame != NULL); So, do you feel
     lucky? */
  if (!deprecated_selected_frame)
    {
      CORE_ADDR pc = read_pc ();
      if (addr_in_block != NULL)
	*addr_in_block = pc;
      return block_for_pc (pc);
    }
  return get_frame_block (deprecated_selected_frame, 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)
{
  struct frame_info *prev;
  struct frame_info *frame1;

  /* Going up is simple: just do get_prev_frame enough times
     or until initial frame is reached.  */
  while (*level_offset_ptr > 0)
    {
      prev = get_prev_frame (frame);
      if (prev == 0)
	break;
      (*level_offset_ptr)--;
      frame = prev;
    }
  /* Going down is just as simple.  */
  if (*level_offset_ptr < 0)
    {
      while (*level_offset_ptr < 0)
	{
	  frame1 = get_next_frame (frame);
	  if (!frame1)
	    break;
	  frame = frame1;
	  (*level_offset_ptr)++;
	}
    }
  return frame;
}

/* The "select_frame" command.  With no arg, NOP.
   With arg LEVEL_EXP, select the frame at level LEVEL 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)
{
  struct frame_info *frame;
  int level = frame_relative_level (deprecated_selected_frame);

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

  frame = parse_frame_specification (level_exp);

  select_frame (frame);
  if (level != frame_relative_level (deprecated_selected_frame))
    selected_frame_level_changed_event (frame_relative_level (deprecated_selected_frame));
}

/* The "frame" command.  With no arg, print selected frame briefly.
   With arg, behaves like select_frame and then prints the selected
   frame.  */

void
frame_command (char *level_exp, int from_tty)
{
  select_frame_command (level_exp, from_tty);
  print_stack_frame (deprecated_selected_frame,
		     frame_relative_level (deprecated_selected_frame), 1);
}

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

static void
current_frame_command (char *level_exp, int from_tty)
{
  if (target_has_stack == 0 || deprecated_selected_frame == 0)
    error ("No stack.");
  print_stack_frame (deprecated_selected_frame,
			  frame_relative_level (deprecated_selected_frame), 1);
}

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

static void
up_silently_base (char *count_exp)
{
  struct frame_info *fi;
  int count = 1, count1;
  if (count_exp)
    count = parse_and_eval_long (count_exp);
  count1 = count;

  if (target_has_stack == 0 || deprecated_selected_frame == 0)
    error ("No stack.");

  fi = find_relative_frame (deprecated_selected_frame, &count1);
  if (count1 != 0 && count_exp == 0)
    error ("Initial frame selected; you cannot go up.");
  select_frame (fi);
  selected_frame_level_changed_event (frame_relative_level (deprecated_selected_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 (deprecated_selected_frame,
		     frame_relative_level (deprecated_selected_frame), 1);
}

/* Select the frame down one or COUNT 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, count1;
  if (count_exp)
    count = -parse_and_eval_long (count_exp);
  count1 = count;

  if (target_has_stack == 0 || deprecated_selected_frame == 0)
    error ("No stack.");

  frame = find_relative_frame (deprecated_selected_frame, &count1);
  if (count1 != 0 && count_exp == 0)
    {

      /* 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 (i.e., innermost) frame selected; you cannot go down.");
    }

  select_frame (frame);
  selected_frame_level_changed_event (frame_relative_level (deprecated_selected_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 (deprecated_selected_frame,
		     frame_relative_level (deprecated_selected_frame), 1);
}

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

  /* FIXME: cagney/2003-10-20: Perform a minimal existance test on the
     target.  If that fails, error out.  For the moment don't rely on
     get_selected_frame as it's error message is the the singularly
     obscure "No registers".  */
  if (!target_has_registers)
    error ("No selected frame.");
  thisfun = get_frame_function (get_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;
      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
           occure.  */
	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 ());
    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_VAUE in the just-returned register set.  */
  if (return_value != NULL)
    {
      struct type *return_type = VALUE_TYPE (return_value);
      if (!gdbarch_return_value_p (current_gdbarch))
	{
	  STORE_RETURN_VALUE (return_type, current_regcache,
			      VALUE_CONTENTS (return_value));
	}
      /* FIXME: cagney/2004-01-17: If extract_returned_value_address
         is available and the function is using
         RETURN_VALUE_STRUCT_CONVENTION, should use it to find the
         address of the returned value so that it can be assigned.  */
      else
	{
	  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.  */
  /* NOTE: cagney/2003-01-18: Is this silly?  Instead of popping all
     the frames in sequence, should this code just pop the dummy frame
     directly?  */
#ifdef DEPRECATED_CALL_DUMMY_HAS_COMPLETED
  /* Since all up-to-date architectures return direct to the dummy
     breakpoint address, a dummy frame has, by definition, always
     completed.  Hence this method is no longer needed.  */
  if (DEPRECATED_CALL_DUMMY_HAS_COMPLETED (read_pc(), read_sp (),
					   get_frame_base (get_current_frame ())))
    frame_pop (get_current_frame ());
#else
  if (get_frame_type (get_current_frame ()) == DUMMY_FRAME)
    frame_pop (get_current_frame ());
#endif

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

  if (arg != (char *) NULL)
    return;

  fp = 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 == (CORE_ADDR) 0 ||
	  find_pc_partial_function (sals.sals[i].pc,
				    (char **) NULL,
				    &func_bounds[i].low,
				    &func_bounds[i].high) == 0)
	{
	  func_bounds[i].low =
	    func_bounds[i].high = (CORE_ADDR) NULL;
	}
    }

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

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

enum language
get_frame_language (void)
{
  struct symtab *s;
  enum language flang;		/* The language of the current frame */

  if (deprecated_selected_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 which is
         guaranteed to be inside the frame's code block.  */
      s = find_pc_symtab (get_frame_address_in_block (deprecated_selected_frame));
      if (s)
	flang = s->language;
      else
	flang = language_unknown;
    }
  else
    flang = language_unknown;

  return flang;
}

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>.\nUsage: 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
}