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/* Perform an inferior function call, 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, 2006, 2007,

   2008 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 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "breakpoint.h"

#include "target.h"

#include "regcache.h"

#include "inferior.h"

#include "gdb_assert.h"

#include "block.h"

#include "gdbcore.h"

#include "language.h"

#include "objfiles.h"

#include "gdbcmd.h"

#include "command.h"

#include "gdb_string.h"

#include "infcall.h"

#include "dummy-frame.h"

#include "ada-lang.h"

/* NOTE: cagney/2003-04-16: What's the future of this code?

   GDB needs an asynchronous expression evaluator, that means an

   asynchronous inferior function call implementation, and that in

   turn means restructuring the code so that it is event driven.  */

/* How you should pass arguments to a function depends on whether it

   was defined in K&R style or prototype style.  If you define a

   function using the K&R syntax that takes a `float' argument, then

   callers must pass that argument as a `double'.  If you define the

   function using the prototype syntax, then you must pass the

   argument as a `float', with no promotion.

   Unfortunately, on certain older platforms, the debug info doesn't

   indicate reliably how each function was defined.  A function type's

   TYPE_FLAG_PROTOTYPED flag may be clear, even if the function was

   defined in prototype style.  When calling a function whose

   TYPE_FLAG_PROTOTYPED flag is clear, GDB consults this flag to

   decide what to do.

   For modern targets, it is proper to assume that, if the prototype

   flag is clear, that can be trusted: `float' arguments should be

   promoted to `double'.  For some older targets, if the prototype

   flag is clear, that doesn't tell us anything.  The default is to

   trust the debug information; the user can override this behavior

   with "set coerce-float-to-double 0".  */

static int coerce_float_to_double_p = 1;

static void

show_coerce_float_to_double_p (struct ui_file *file, int from_tty,

                               struct cmd_list_element *c, const char *value)

{

  fprintf_filtered (file, _("\

Coercion of floats to doubles when calling functions is %s.\n"),

                    value);

}

/* This boolean tells what gdb should do if a signal is received while

   in a function called from gdb (call dummy).  If set, gdb unwinds

   the stack and restore the context to what as it was before the

   call.

   The default is to stop in the frame where the signal was received. */

int unwind_on_signal_p = 0;

static void

show_unwind_on_signal_p (struct ui_file *file, int from_tty,

                         struct cmd_list_element *c, const char *value)

{

  fprintf_filtered (file, _("\

Unwinding of stack if a signal is received while in a call dummy is %s.\n"),

                    value);

}

/* Perform the standard coercions that are specified

   for arguments to be passed to C or Ada functions.

   If PARAM_TYPE is non-NULL, it is the expected parameter type.

   IS_PROTOTYPED is non-zero if the function declaration is prototyped.

   SP is the stack pointer were additional data can be pushed (updating

   its value as needed).  */

static struct value *

value_arg_coerce (struct value *arg, struct type *param_type,

                  int is_prototyped, CORE_ADDR *sp)

{

  struct type *arg_type = check_typedef (value_type (arg));

  struct type *type

    = param_type ? check_typedef (param_type) : arg_type;

  /* Perform any Ada-specific coercion first.  */

  if (current_language->la_language == language_ada)

    arg = ada_convert_actual (arg, type, sp);

  switch (TYPE_CODE (type))

    {

    case TYPE_CODE_REF:

      {

        struct value *new_value;

        if (TYPE_CODE (arg_type) == TYPE_CODE_REF)

          return value_cast_pointers (type, arg);

        /* Cast the value to the reference's target type, and then

           convert it back to a reference.  This will issue an error

           if the value was not previously in memory - in some cases

           we should clearly be allowing this, but how?  */

        new_value = value_cast (TYPE_TARGET_TYPE (type), arg);

        new_value = value_ref (new_value);

        return new_value;

      }

    case TYPE_CODE_INT:

    case TYPE_CODE_CHAR:

    case TYPE_CODE_BOOL:

    case TYPE_CODE_ENUM:

      /* If we don't have a prototype, coerce to integer type if necessary.  */

      if (!is_prototyped)

        {

          if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_int))

            type = builtin_type_int;

        }

      /* Currently all target ABIs require at least the width of an integer

         type for an argument.  We may have to conditionalize the following

         type coercion for future targets.  */

      if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_int))

        type = builtin_type_int;

      break;

    case TYPE_CODE_FLT:

      if (!is_prototyped && coerce_float_to_double_p)

        {

          if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_double))

            type = builtin_type_double;

          else if (TYPE_LENGTH (type) > TYPE_LENGTH (builtin_type_double))

            type = builtin_type_long_double;

        }

      break;

    case TYPE_CODE_FUNC:

      type = lookup_pointer_type (type);

      break;

    case TYPE_CODE_ARRAY:

      /* Arrays are coerced to pointers to their first element, unless

         they are vectors, in which case we want to leave them alone,

         because they are passed by value.  */

      if (current_language->c_style_arrays)

        if (!TYPE_VECTOR (type))

          type = lookup_pointer_type (TYPE_TARGET_TYPE (type));

      break;

    case TYPE_CODE_UNDEF:

    case TYPE_CODE_PTR:

    case TYPE_CODE_STRUCT:

    case TYPE_CODE_UNION:

    case TYPE_CODE_VOID:

    case TYPE_CODE_SET:

    case TYPE_CODE_RANGE:

    case TYPE_CODE_STRING:

    case TYPE_CODE_BITSTRING:

    case TYPE_CODE_ERROR:

    case TYPE_CODE_MEMBERPTR:

    case TYPE_CODE_METHODPTR:

    case TYPE_CODE_METHOD:

    case TYPE_CODE_COMPLEX:

    default:

      break;

    }

  return value_cast (type, arg);

}

/* Determine a function's address and its return type from its value.

   Calls error() if the function is not valid for calling.  */

CORE_ADDR

find_function_addr (struct value *function, struct type **retval_type)

{

  struct type *ftype = check_typedef (value_type (function));

  enum type_code code = TYPE_CODE (ftype);

  struct type *value_type;

  CORE_ADDR funaddr;

  /* If it's a member function, just look at the function

     part of it.  */

  /* Determine address to call.  */

  if (code == TYPE_CODE_FUNC || code == TYPE_CODE_METHOD)

    {

      funaddr = VALUE_ADDRESS (function);

      value_type = TYPE_TARGET_TYPE (ftype);

    }

  else if (code == TYPE_CODE_PTR)

    {

      funaddr = value_as_address (function);

      ftype = check_typedef (TYPE_TARGET_TYPE (ftype));

      if (TYPE_CODE (ftype) == TYPE_CODE_FUNC

          || TYPE_CODE (ftype) == TYPE_CODE_METHOD)

        {

          funaddr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,

                                                        funaddr,

                                                        &current_target);

          value_type = TYPE_TARGET_TYPE (ftype);

        }

      else

        value_type = builtin_type_int;

    }

  else if (code == TYPE_CODE_INT)

    {

      /* Handle the case of functions lacking debugging info.

         Their values are characters since their addresses are char */

      if (TYPE_LENGTH (ftype) == 1)

        funaddr = value_as_address (value_addr (function));

      else

        {

          /* Handle function descriptors lacking debug info.  */

          int found_descriptor = 0;

          if (VALUE_LVAL (function) == lval_memory)

            {

              CORE_ADDR nfunaddr;

              funaddr = value_as_address (value_addr (function));

              nfunaddr = funaddr;

              funaddr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,

                                                            funaddr,

                                                            &current_target);

              if (funaddr != nfunaddr)

                found_descriptor = 1;

            }

          if (!found_descriptor)

            /* Handle integer used as address of a function.  */

            funaddr = (CORE_ADDR) value_as_long (function);

        }

      value_type = builtin_type_int;

    }

  else

    error (_("Invalid data type for function to be called."));

  if (retval_type != NULL)

    *retval_type = value_type;

  return funaddr + gdbarch_deprecated_function_start_offset (current_gdbarch);

}

/* Call breakpoint_auto_delete on the current contents of the bpstat

   pointed to by arg (which is really a bpstat *).  */

static void

breakpoint_auto_delete_contents (void *arg)

{

  breakpoint_auto_delete (*(bpstat *) arg);

}

static CORE_ADDR

generic_push_dummy_code (struct gdbarch *gdbarch,

                         CORE_ADDR sp, CORE_ADDR funaddr,

                         struct value **args, int nargs,

                         struct type *value_type,

                         CORE_ADDR *real_pc, CORE_ADDR *bp_addr,

                         struct regcache *regcache)

{

  /* Something here to findout the size of a breakpoint and then

     allocate space for it on the stack.  */

  int bplen;

  /* This code assumes frame align.  */

  gdb_assert (gdbarch_frame_align_p (gdbarch));

  /* Force the stack's alignment.  The intent is to ensure that the SP

     is aligned to at least a breakpoint instruction's boundary.  */

  sp = gdbarch_frame_align (gdbarch, sp);

  /* Allocate space for, and then position the breakpoint on the

     stack.  */

  if (gdbarch_inner_than (gdbarch, 1, 2))

    {

      CORE_ADDR bppc = sp;

      gdbarch_breakpoint_from_pc (gdbarch, &bppc, &bplen);

      sp = gdbarch_frame_align (gdbarch, sp - bplen);

      (*bp_addr) = sp;

      /* Should the breakpoint size/location be re-computed here?  */

    }

  else

    {

      (*bp_addr) = sp;

      gdbarch_breakpoint_from_pc (gdbarch, bp_addr, &bplen);

      sp = gdbarch_frame_align (gdbarch, sp + bplen);

    }

  /* Inferior resumes at the function entry point.  */

  (*real_pc) = funaddr;

  return sp;

}

/* For CALL_DUMMY_ON_STACK, push a breakpoint sequence that the called

   function returns to.  */

static CORE_ADDR

push_dummy_code (struct gdbarch *gdbarch,

                 CORE_ADDR sp, CORE_ADDR funaddr,

                 struct value **args, int nargs,

                 struct type *value_type,

                 CORE_ADDR *real_pc, CORE_ADDR *bp_addr,

                 struct regcache *regcache)

{

  if (gdbarch_push_dummy_code_p (gdbarch))

    return gdbarch_push_dummy_code (gdbarch, sp, funaddr,

                                    args, nargs, value_type, real_pc, bp_addr,

                                    regcache);

  else

    return generic_push_dummy_code (gdbarch, sp, funaddr,

                                    args, nargs, value_type, real_pc, bp_addr,

                                    regcache);

}

/* All this stuff with a dummy frame may seem unnecessarily complicated

   (why not just save registers in GDB?).  The purpose of pushing a dummy

   frame which looks just like a real frame is so that if you call a

   function and then hit a breakpoint (get a signal, etc), "backtrace"

   will look right.  Whether the backtrace needs to actually show the

   stack at the time the inferior function was called is debatable, but

   it certainly needs to not display garbage.  So if you are contemplating

   making dummy frames be different from normal frames, consider that.  */

/* Perform a function call in the inferior.

   ARGS is a vector of values of arguments (NARGS of them).

   FUNCTION is a value, the function to be called.

   Returns a value representing what the function returned.

   May fail to return, if a breakpoint or signal is hit

   during the execution of the function.

   ARGS is modified to contain coerced values. */

struct value *

call_function_by_hand (struct value *function, int nargs, struct value **args)

{

  CORE_ADDR sp;

  CORE_ADDR dummy_addr;

  struct type *values_type, *target_values_type;

  unsigned char struct_return = 0, lang_struct_return = 0;

  CORE_ADDR struct_addr = 0;

  struct regcache *retbuf;

  struct cleanup *retbuf_cleanup;

  struct inferior_status *inf_status;

  struct cleanup *inf_status_cleanup;

  CORE_ADDR funaddr;

  CORE_ADDR real_pc;

  struct type *ftype = check_typedef (value_type (function));

  CORE_ADDR bp_addr;

  struct regcache *caller_regcache;

  struct cleanup *caller_regcache_cleanup;

  struct frame_id dummy_id;

  struct cleanup *args_cleanup;

  struct frame_info *frame;

  struct gdbarch *gdbarch;

  if (TYPE_CODE (ftype) == TYPE_CODE_PTR)

    ftype = check_typedef (TYPE_TARGET_TYPE (ftype));

  if (!target_has_execution)

    noprocess ();

  frame = get_current_frame ();

  gdbarch = get_frame_arch (frame);

  if (!gdbarch_push_dummy_call_p (gdbarch))

    error (_("This target does not support function calls"));

  /* Create a cleanup chain that contains the retbuf (buffer

     containing the register values).  This chain is create BEFORE the

     inf_status chain so that the inferior status can cleaned up

     (restored or discarded) without having the retbuf freed.  */

  retbuf = regcache_xmalloc (gdbarch);

  retbuf_cleanup = make_cleanup_regcache_xfree (retbuf);

  /* A cleanup for the inferior status.  Create this AFTER the retbuf

     so that this can be discarded or applied without interfering with

     the regbuf.  */

  inf_status = save_inferior_status (1);

  inf_status_cleanup = make_cleanup_restore_inferior_status (inf_status);

  /* Save the caller's registers so that they can be restored once the

     callee returns.  To allow nested calls the registers are (further

     down) pushed onto a dummy frame stack.  Include a cleanup (which

     is tossed once the regcache has been pushed).  */

  caller_regcache = frame_save_as_regcache (frame);

  caller_regcache_cleanup = make_cleanup_regcache_xfree (caller_regcache);

  /* Ensure that the initial SP is correctly aligned.  */

  {

    CORE_ADDR old_sp = get_frame_sp (frame);

    if (gdbarch_frame_align_p (gdbarch))

      {

        sp = gdbarch_frame_align (gdbarch, old_sp);

        /* NOTE: cagney/2003-08-13: Skip the "red zone".  For some

           ABIs, a function can use memory beyond the inner most stack

           address.  AMD64 called that region the "red zone".  Skip at

           least the "red zone" size before allocating any space on

           the stack.  */

        if (gdbarch_inner_than (gdbarch, 1, 2))

          sp -= gdbarch_frame_red_zone_size (gdbarch);

        else

          sp += gdbarch_frame_red_zone_size (gdbarch);

        /* Still aligned?  */

        gdb_assert (sp == gdbarch_frame_align (gdbarch, sp));

        /* NOTE: cagney/2002-09-18:

           On a RISC architecture, a void parameterless generic dummy

           frame (i.e., no parameters, no result) typically does not

           need to push anything the stack and hence can leave SP and

           FP.  Similarly, a frameless (possibly leaf) function does

           not push anything on the stack and, hence, that too can

           leave FP and SP unchanged.  As a consequence, a sequence of

           void parameterless generic dummy frame calls to frameless

           functions will create a sequence of effectively identical

           frames (SP, FP and TOS and PC the same).  This, not

           suprisingly, results in what appears to be a stack in an

           infinite loop --- when GDB tries to find a generic dummy

           frame on the internal dummy frame stack, it will always

           find the first one.

           To avoid this problem, the code below always grows the

           stack.  That way, two dummy frames can never be identical.

           It does burn a few bytes of stack but that is a small price

           to pay :-).  */

        if (sp == old_sp)

          {

            if (gdbarch_inner_than (gdbarch, 1, 2))

              /* Stack grows down.  */

              sp = gdbarch_frame_align (gdbarch, old_sp - 1);

            else

              /* Stack grows up.  */

              sp = gdbarch_frame_align (gdbarch, old_sp + 1);

          }

        gdb_assert ((gdbarch_inner_than (gdbarch, 1, 2)

                    && sp <= old_sp)

                    || (gdbarch_inner_than (gdbarch, 2, 1)

                       && sp >= old_sp));

      }

    else

      /* FIXME: cagney/2002-09-18: Hey, you loose!

         Who knows how badly aligned the SP is!

         If the generic dummy frame ends up empty (because nothing is

         pushed) GDB won't be able to correctly perform back traces.

         If a target is having trouble with backtraces, first thing to

         do is add FRAME_ALIGN() to the architecture vector. If that

         fails, try unwind_dummy_id().

         If the ABI specifies a "Red Zone" (see the doco) the code

         below will quietly trash it.  */

      sp = old_sp;

  }

  funaddr = find_function_addr (function, &values_type);

  CHECK_TYPEDEF (values_type);

  /* Are we returning a value using a structure return (passing a

     hidden argument pointing to storage) or a normal value return?

     There are two cases: language-mandated structure return and

     target ABI structure return.  The variable STRUCT_RETURN only

     describes the latter.  The language version is handled by passing

     the return location as the first parameter to the function,

     even preceding "this".  This is different from the target

     ABI version, which is target-specific; for instance, on ia64

     the first argument is passed in out0 but the hidden structure

     return pointer would normally be passed in r8.  */

  if (language_pass_by_reference (values_type))

    {

      lang_struct_return = 1;

      /* Tell the target specific argument pushing routine not to

         expect a value.  */

      target_values_type = builtin_type_void;

    }

  else

    {

      struct_return = using_struct_return (values_type);

      target_values_type = values_type;

    }

  /* Determine the location of the breakpoint (and possibly other

     stuff) that the called function will return to.  The SPARC, for a

     function returning a structure or union, needs to make space for

     not just the breakpoint but also an extra word containing the

     size (?) of the structure being passed.  */

  /* The actual breakpoint (at BP_ADDR) is inserted separatly so there

     is no need to write that out.  */

  switch (gdbarch_call_dummy_location (gdbarch))

    {

    case ON_STACK:

      /* "dummy_addr" is here just to keep old targets happy.  New

         targets return that same information via "sp" and "bp_addr".  */

      if (gdbarch_inner_than (gdbarch, 1, 2))

        {

          sp = push_dummy_code (gdbarch, sp, funaddr,

                                args, nargs, target_values_type,

                                &real_pc, &bp_addr, get_current_regcache ());

          dummy_addr = sp;

        }

      else

        {

          dummy_addr = sp;

          sp = push_dummy_code (gdbarch, sp, funaddr,

                                args, nargs, target_values_type,

                                &real_pc, &bp_addr, get_current_regcache ());

        }

      break;

    case AT_ENTRY_POINT:

      real_pc = funaddr;

      dummy_addr = entry_point_address ();

      /* Make certain that the address points at real code, and not a

         function descriptor.  */

      dummy_addr = gdbarch_convert_from_func_ptr_addr (gdbarch,

                                                       dummy_addr,

                                                       &current_target);

      /* A call dummy always consists of just a single breakpoint, so

         it's address is the same as the address of the dummy.  */

      bp_addr = dummy_addr;

      break;

    case AT_SYMBOL:

      /* Some executables define a symbol __CALL_DUMMY_ADDRESS whose

         address is the location where the breakpoint should be

         placed.  Once all targets are using the overhauled frame code

         this can be deleted - ON_STACK is a better option.  */

      {

        struct minimal_symbol *sym;

        sym = lookup_minimal_symbol ("__CALL_DUMMY_ADDRESS", NULL, NULL);

        real_pc = funaddr;

        if (sym)

          dummy_addr = SYMBOL_VALUE_ADDRESS (sym);

        else

          dummy_addr = entry_point_address ();

        /* Make certain that the address points at real code, and not

           a function descriptor.  */

        dummy_addr = gdbarch_convert_from_func_ptr_addr (gdbarch,

                                                         dummy_addr,

                                                         &current_target);

        /* A call dummy always consists of just a single breakpoint,

           so it's address is the same as the address of the dummy.  */

        bp_addr = dummy_addr;

        break;

      }

    default:

      internal_error (__FILE__, __LINE__, _("bad switch"));

    }

  if (nargs < TYPE_NFIELDS (ftype))

    error (_("too few arguments in function call"));

  {

    int i;

    for (i = nargs - 1; i >= 0; i--)

      {

        int prototyped;

        struct type *param_type;

        /* FIXME drow/2002-05-31: Should just always mark methods as

           prototyped.  Can we respect TYPE_VARARGS?  Probably not.  */

        if (TYPE_CODE (ftype) == TYPE_CODE_METHOD)

          prototyped = 1;

        else if (i < TYPE_NFIELDS (ftype))

          prototyped = TYPE_PROTOTYPED (ftype);

        else

          prototyped = 0;

        if (i < TYPE_NFIELDS (ftype))

          param_type = TYPE_FIELD_TYPE (ftype, i);

        else

          param_type = NULL;

        args[i] = value_arg_coerce (args[i], param_type, prototyped, &sp);

        if (param_type != NULL && language_pass_by_reference (param_type))

          args[i] = value_addr (args[i]);

      }

  }

  /* Reserve space for the return structure to be written on the

     stack, if necessary.  Make certain that the value is correctly

     aligned. */

  if (struct_return || lang_struct_return)

    {

      int len = TYPE_LENGTH (values_type);

      if (gdbarch_inner_than (gdbarch, 1, 2))

        {

          /* Stack grows downward.  Align STRUCT_ADDR and SP after

             making space for the return value.  */

          sp -= len;

          if (gdbarch_frame_align_p (gdbarch))

            sp = gdbarch_frame_align (gdbarch, sp);

          struct_addr = sp;

        }

      else

        {

          /* Stack grows upward.  Align the frame, allocate space, and

             then again, re-align the frame??? */

          if (gdbarch_frame_align_p (gdbarch))

            sp = gdbarch_frame_align (gdbarch, sp);

          struct_addr = sp;

          sp += len;

          if (gdbarch_frame_align_p (gdbarch))

            sp = gdbarch_frame_align (gdbarch, sp);

        }

    }

  if (lang_struct_return)

    {

      struct value **new_args;

      /* Add the new argument to the front of the argument list.  */

      new_args = xmalloc (sizeof (struct value *) * (nargs + 1));

      new_args[0] = value_from_pointer (lookup_pointer_type (values_type),

                                        struct_addr);

      memcpy (&new_args[1], &args[0], sizeof (struct value *) * nargs);

      args = new_args;

      nargs++;

      args_cleanup = make_cleanup (xfree, args);

    }

  else

    args_cleanup = make_cleanup (null_cleanup, NULL);

  /* Create the dummy stack frame.  Pass in the call dummy address as,

     presumably, the ABI code knows where, in the call dummy, the

     return address should be pointed.  */

  sp = gdbarch_push_dummy_call (gdbarch, function, get_current_regcache (),

                                bp_addr, nargs, args,

                                sp, struct_return, struct_addr);

  do_cleanups (args_cleanup);

  /* Set up a frame ID for the dummy frame so we can pass it to

     set_momentary_breakpoint.  We need to give the breakpoint a frame

     ID so that the breakpoint code can correctly re-identify the

     dummy breakpoint.  */

  /* Sanity.  The exact same SP value is returned by PUSH_DUMMY_CALL,

     saved as the dummy-frame TOS, and used by unwind_dummy_id to form

     the frame ID's stack address.  */

  dummy_id = frame_id_build (sp, bp_addr);

  /* Create a momentary breakpoint at the return address of the

     inferior.  That way it breaks when it returns.  */

  {

    struct breakpoint *bpt;

    struct symtab_and_line sal;

    init_sal (&sal);            /* initialize to zeroes */

    sal.pc = bp_addr;

    sal.section = find_pc_overlay (sal.pc);

    /* Sanity.  The exact same SP value is returned by

       PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by

       unwind_dummy_id to form the frame ID's stack address.  */

    bpt = set_momentary_breakpoint (sal, dummy_id, bp_call_dummy);

    bpt->disposition = disp_del;

  }

  /* Everything's ready, push all the info needed to restore the

     caller (and identify the dummy-frame) onto the dummy-frame

     stack.  */

  dummy_frame_push (caller_regcache, &dummy_id);

  discard_cleanups (caller_regcache_cleanup);

  /* - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP -

     If you're looking to implement asynchronous dummy-frames, then

     just below is the place to chop this function in two..  */

  /* Now proceed, having reached the desired place.  */

  clear_proceed_status ();

  /* Execute a "stack dummy", a piece of code stored in the stack by

     the debugger to be executed in the inferior.

     The dummy's frame is automatically popped whenever that break is

     hit.  If that is the first time the program stops,

     call_function_by_hand returns to its caller with that frame

     already gone and sets RC to 0.

     Otherwise, set RC to a non-zero value.  If the called function

     receives a random signal, we do not allow the user to continue

     executing it as this may not work.  The dummy frame is poped and

     we return 1.  If we hit a breakpoint, we leave the frame in place

     and return 2 (the frame will eventually be popped when we do hit

     the dummy end breakpoint).  */

  {

    struct cleanup *old_cleanups = make_cleanup (null_cleanup, 0);

    int saved_async = 0;

    /* If all error()s out of proceed ended up calling normal_stop

       (and perhaps they should; it already does in the special case

       of error out of resume()), then we wouldn't need this.  */

    make_cleanup (breakpoint_auto_delete_contents, &stop_bpstat);

    disable_watchpoints_before_interactive_call_start ();

    proceed_to_finish = 1;      /* We want stop_registers, please... */

    if (target_can_async_p ())

      saved_async = target_async_mask (0);

    proceed (real_pc, TARGET_SIGNAL_0, 0);

    if (saved_async)

      target_async_mask (saved_async);

    enable_watchpoints_after_interactive_call_stop ();

    discard_cleanups (old_cleanups);

  }

  if (stopped_by_random_signal || !stop_stack_dummy)

    {

      /* Find the name of the function we're about to complain about.  */

      const char *name = NULL;

      {