gdb/infcall.c

   1 /* Perform an inferior function call, for GDB, the GNU debugger.
   2
   3    Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
   4    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
   5    Free Software Foundation, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #include "defs.h"
  25 #include "breakpoint.h"
  26 #include "target.h"
  27 #include "regcache.h"
  28 #include "inferior.h"
  29 #include "gdb_assert.h"
  30 #include "block.h"
  31 #include "gdbcore.h"
  32 #include "language.h"
  33 #include "objfiles.h"
  34 #include "gdbcmd.h"
  35 #include "command.h"
  36 #include "gdb_string.h"
  37 #include "infcall.h"
  38 #include "dummy-frame.h"
  39
  40 /* NOTE: cagney/2003-04-16: What's the future of this code?
  41
  42    GDB needs an asynchronous expression evaluator, that means an
  43    asynchronous inferior function call implementation, and that in
  44    turn means restructuring the code so that it is event driven.  */
  45
  46 /* How you should pass arguments to a function depends on whether it
  47    was defined in K&R style or prototype style.  If you define a
  48    function using the K&R syntax that takes a `float' argument, then
  49    callers must pass that argument as a `double'.  If you define the
  50    function using the prototype syntax, then you must pass the
  51    argument as a `float', with no promotion.
  52
  53    Unfortunately, on certain older platforms, the debug info doesn't
  54    indicate reliably how each function was defined.  A function type's
  55    TYPE_FLAG_PROTOTYPED flag may be clear, even if the function was
  56    defined in prototype style.  When calling a function whose
  57    TYPE_FLAG_PROTOTYPED flag is clear, GDB consults this flag to
  58    decide what to do.
  59
  60    For modern targets, it is proper to assume that, if the prototype
  61    flag is clear, that can be trusted: `float' arguments should be
  62    promoted to `double'.  For some older targets, if the prototype
  63    flag is clear, that doesn't tell us anything.  The default is to
  64    trust the debug information; the user can override this behavior
  65    with "set coerce-float-to-double 0".  */
  66
  67 static int coerce_float_to_double_p = 1;
  68
  69 /* This boolean tells what gdb should do if a signal is received while
  70    in a function called from gdb (call dummy).  If set, gdb unwinds
  71    the stack and restore the context to what as it was before the
  72    call.
  73
  74    The default is to stop in the frame where the signal was received. */
  75
  76 int unwind_on_signal_p = 0;
  77
  78 /* Perform the standard coercions that are specified
  79    for arguments to be passed to C functions.
  80
  81    If PARAM_TYPE is non-NULL, it is the expected parameter type.
  82    IS_PROTOTYPED is non-zero if the function declaration is prototyped.  */
  83
  84 static struct value *
  85 value_arg_coerce (struct value *arg, struct type *param_type,
  86                   int is_prototyped)
  87 {
  88   struct type *arg_type = check_typedef (value_type (arg));
  89   struct type *type
  90     = param_type ? check_typedef (param_type) : arg_type;
  91
  92   switch (TYPE_CODE (type))
  93     {
  94     case TYPE_CODE_REF:
  95       if (TYPE_CODE (arg_type) != TYPE_CODE_REF
  96           && TYPE_CODE (arg_type) != TYPE_CODE_PTR)
  97         {
  98           arg = value_addr (arg);
  99           deprecated_set_value_type (arg, param_type);
 100           return arg;
 101         }
 102       break;
 103     case TYPE_CODE_INT:
 104     case TYPE_CODE_CHAR:
 105     case TYPE_CODE_BOOL:
 106     case TYPE_CODE_ENUM:
 107       /* If we don't have a prototype, coerce to integer type if necessary.  */
 108       if (!is_prototyped)
 109         {
 110           if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_int))
 111             type = builtin_type_int;
 112         }
 113       /* Currently all target ABIs require at least the width of an integer
 114          type for an argument.  We may have to conditionalize the following
 115          type coercion for future targets.  */
 116       if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_int))
 117         type = builtin_type_int;
 118       break;
 119     case TYPE_CODE_FLT:
 120       if (!is_prototyped && coerce_float_to_double_p)
 121         {
 122           if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_double))
 123             type = builtin_type_double;
 124           else if (TYPE_LENGTH (type) > TYPE_LENGTH (builtin_type_double))
 125             type = builtin_type_long_double;
 126         }
 127       break;
 128     case TYPE_CODE_FUNC:
 129       type = lookup_pointer_type (type);
 130       break;
 131     case TYPE_CODE_ARRAY:
 132       /* Arrays are coerced to pointers to their first element, unless
 133          they are vectors, in which case we want to leave them alone,
 134          because they are passed by value.  */
 135       if (current_language->c_style_arrays)
 136         if (!TYPE_VECTOR (type))
 137           type = lookup_pointer_type (TYPE_TARGET_TYPE (type));
 138       break;
 139     case TYPE_CODE_UNDEF:
 140     case TYPE_CODE_PTR:
 141     case TYPE_CODE_STRUCT:
 142     case TYPE_CODE_UNION:
 143     case TYPE_CODE_VOID:
 144     case TYPE_CODE_SET:
 145     case TYPE_CODE_RANGE:
 146     case TYPE_CODE_STRING:
 147     case TYPE_CODE_BITSTRING:
 148     case TYPE_CODE_ERROR:
 149     case TYPE_CODE_MEMBER:
 150     case TYPE_CODE_METHOD:
 151     case TYPE_CODE_COMPLEX:
 152     default:
 153       break;
 154     }
 155
 156   return value_cast (type, arg);
 157 }
 158
 159 /* Determine a function's address and its return type from its value.
 160    Calls error() if the function is not valid for calling.  */
 161
 162 CORE_ADDR
 163 find_function_addr (struct value *function, struct type **retval_type)
 164 {
 165   struct type *ftype = check_typedef (value_type (function));
 166   enum type_code code = TYPE_CODE (ftype);
 167   struct type *value_type;
 168   CORE_ADDR funaddr;
 169
 170   /* If it's a member function, just look at the function
 171      part of it.  */
 172
 173   /* Determine address to call.  */
 174   if (code == TYPE_CODE_FUNC || code == TYPE_CODE_METHOD)
 175     {
 176       funaddr = VALUE_ADDRESS (function);
 177       value_type = TYPE_TARGET_TYPE (ftype);
 178     }
 179   else if (code == TYPE_CODE_PTR)
 180     {
 181       funaddr = value_as_address (function);
 182       ftype = check_typedef (TYPE_TARGET_TYPE (ftype));
 183       if (TYPE_CODE (ftype) == TYPE_CODE_FUNC
 184           || TYPE_CODE (ftype) == TYPE_CODE_METHOD)
 185         {
 186           funaddr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 187                                                         funaddr,
 188                                                         &current_target);
 189           value_type = TYPE_TARGET_TYPE (ftype);
 190         }
 191       else
 192         value_type = builtin_type_int;
 193     }
 194   else if (code == TYPE_CODE_INT)
 195     {
 196       /* Handle the case of functions lacking debugging info.
 197          Their values are characters since their addresses are char */
 198       if (TYPE_LENGTH (ftype) == 1)
 199         funaddr = value_as_address (value_addr (function));
 200       else
 201         /* Handle integer used as address of a function.  */
 202         funaddr = (CORE_ADDR) value_as_long (function);
 203
 204       value_type = builtin_type_int;
 205     }
 206   else
 207     error (_("Invalid data type for function to be called."));
 208
 209   if (retval_type != NULL)
 210     *retval_type = value_type;
 211   return funaddr + DEPRECATED_FUNCTION_START_OFFSET;
 212 }
 213
 214 /* Call breakpoint_auto_delete on the current contents of the bpstat
 215    pointed to by arg (which is really a bpstat *).  */
 216
 217 static void
 218 breakpoint_auto_delete_contents (void *arg)
 219 {
 220   breakpoint_auto_delete (*(bpstat *) arg);
 221 }
 222
 223 static CORE_ADDR
 224 generic_push_dummy_code (struct gdbarch *gdbarch,
 225                          CORE_ADDR sp, CORE_ADDR funaddr, int using_gcc,
 226                          struct value **args, int nargs,
 227                          struct type *value_type,
 228                          CORE_ADDR *real_pc, CORE_ADDR *bp_addr)
 229 {
 230   /* Something here to findout the size of a breakpoint and then
 231      allocate space for it on the stack.  */
 232   int bplen;
 233   /* This code assumes frame align.  */
 234   gdb_assert (gdbarch_frame_align_p (gdbarch));
 235   /* Force the stack's alignment.  The intent is to ensure that the SP
 236      is aligned to at least a breakpoint instruction's boundary.  */
 237   sp = gdbarch_frame_align (gdbarch, sp);
 238   /* Allocate space for, and then position the breakpoint on the
 239      stack.  */
 240   if (gdbarch_inner_than (gdbarch, 1, 2))
 241     {
 242       CORE_ADDR bppc = sp;
 243       gdbarch_breakpoint_from_pc (gdbarch, &bppc, &bplen);
 244       sp = gdbarch_frame_align (gdbarch, sp - bplen);
 245       (*bp_addr) = sp;
 246       /* Should the breakpoint size/location be re-computed here?  */
 247     }
 248   else
 249     {
 250       (*bp_addr) = sp;
 251       gdbarch_breakpoint_from_pc (gdbarch, bp_addr, &bplen);
 252       sp = gdbarch_frame_align (gdbarch, sp + bplen);
 253     }
 254   /* Inferior resumes at the function entry point.  */
 255   (*real_pc) = funaddr;
 256   return sp;
 257 }
 258
 259 /* For CALL_DUMMY_ON_STACK, push a breakpoint sequence that the called
 260    function returns to.  */
 261
 262 static CORE_ADDR
 263 push_dummy_code (struct gdbarch *gdbarch,
 264                  CORE_ADDR sp, CORE_ADDR funaddr, int using_gcc,
 265                  struct value **args, int nargs,
 266                  struct type *value_type,
 267                  CORE_ADDR *real_pc, CORE_ADDR *bp_addr)
 268 {
 269   if (gdbarch_push_dummy_code_p (gdbarch))
 270     return gdbarch_push_dummy_code (gdbarch, sp, funaddr, using_gcc,
 271                                     args, nargs, value_type, real_pc, bp_addr);
 272   else
 273     return generic_push_dummy_code (gdbarch, sp, funaddr, using_gcc,
 274                                     args, nargs, value_type, real_pc, bp_addr);
 275 }
 276
 277 /* All this stuff with a dummy frame may seem unnecessarily complicated
 278    (why not just save registers in GDB?).  The purpose of pushing a dummy
 279    frame which looks just like a real frame is so that if you call a
 280    function and then hit a breakpoint (get a signal, etc), "backtrace"
 281    will look right.  Whether the backtrace needs to actually show the
 282    stack at the time the inferior function was called is debatable, but
 283    it certainly needs to not display garbage.  So if you are contemplating
 284    making dummy frames be different from normal frames, consider that.  */
 285
 286 /* Perform a function call in the inferior.
 287    ARGS is a vector of values of arguments (NARGS of them).
 288    FUNCTION is a value, the function to be called.
 289    Returns a value representing what the function returned.
 290    May fail to return, if a breakpoint or signal is hit
 291    during the execution of the function.
 292
 293    ARGS is modified to contain coerced values. */
 294
 295 struct value *
 296 call_function_by_hand (struct value *function, int nargs, struct value **args)
 297 {
 298   CORE_ADDR sp;
 299   CORE_ADDR dummy_addr;
 300   struct type *values_type;
 301   unsigned char struct_return;
 302   CORE_ADDR struct_addr = 0;
 303   struct regcache *retbuf;
 304   struct cleanup *retbuf_cleanup;
 305   struct inferior_status *inf_status;
 306   struct cleanup *inf_status_cleanup;
 307   CORE_ADDR funaddr;
 308   int using_gcc;                /* Set to version of gcc in use, or zero if not gcc */
 309   CORE_ADDR real_pc;
 310   struct type *ftype = check_typedef (value_type (function));
 311   CORE_ADDR bp_addr;
 312   struct regcache *caller_regcache;
 313   struct cleanup *caller_regcache_cleanup;
 314   struct frame_id dummy_id;
 315
 316   if (!target_has_execution)
 317     noprocess ();
 318
 319   /* Create a cleanup chain that contains the retbuf (buffer
 320      containing the register values).  This chain is create BEFORE the
 321      inf_status chain so that the inferior status can cleaned up
 322      (restored or discarded) without having the retbuf freed.  */
 323   retbuf = regcache_xmalloc (current_gdbarch);
 324   retbuf_cleanup = make_cleanup_regcache_xfree (retbuf);
 325
 326   /* A cleanup for the inferior status.  Create this AFTER the retbuf
 327      so that this can be discarded or applied without interfering with
 328      the regbuf.  */
 329   inf_status = save_inferior_status (1);
 330   inf_status_cleanup = make_cleanup_restore_inferior_status (inf_status);
 331
 332   /* Save the caller's registers so that they can be restored once the
 333      callee returns.  To allow nested calls the registers are (further
 334      down) pushed onto a dummy frame stack.  Include a cleanup (which
 335      is tossed once the regcache has been pushed).  */
 336   caller_regcache = frame_save_as_regcache (get_current_frame ());
 337   caller_regcache_cleanup = make_cleanup_regcache_xfree (caller_regcache);
 338
 339   /* Ensure that the initial SP is correctly aligned.  */
 340   {
 341     CORE_ADDR old_sp = read_sp ();
 342     if (gdbarch_frame_align_p (current_gdbarch))
 343       {
 344         sp = gdbarch_frame_align (current_gdbarch, old_sp);
 345         /* NOTE: cagney/2003-08-13: Skip the "red zone".  For some
 346            ABIs, a function can use memory beyond the inner most stack
 347            address.  AMD64 called that region the "red zone".  Skip at
 348            least the "red zone" size before allocating any space on
 349            the stack.  */
 350         if (INNER_THAN (1, 2))
 351           sp -= gdbarch_frame_red_zone_size (current_gdbarch);
 352         else
 353           sp += gdbarch_frame_red_zone_size (current_gdbarch);
 354         /* Still aligned?  */
 355         gdb_assert (sp == gdbarch_frame_align (current_gdbarch, sp));
 356         /* NOTE: cagney/2002-09-18:
 357
 358            On a RISC architecture, a void parameterless generic dummy
 359            frame (i.e., no parameters, no result) typically does not
 360            need to push anything the stack and hence can leave SP and
 361            FP.  Similarly, a frameless (possibly leaf) function does
 362            not push anything on the stack and, hence, that too can
 363            leave FP and SP unchanged.  As a consequence, a sequence of
 364            void parameterless generic dummy frame calls to frameless
 365            functions will create a sequence of effectively identical
 366            frames (SP, FP and TOS and PC the same).  This, not
 367            suprisingly, results in what appears to be a stack in an
 368            infinite loop --- when GDB tries to find a generic dummy
 369            frame on the internal dummy frame stack, it will always
 370            find the first one.
 371
 372            To avoid this problem, the code below always grows the
 373            stack.  That way, two dummy frames can never be identical.
 374            It does burn a few bytes of stack but that is a small price
 375            to pay :-).  */
 376         if (sp == old_sp)
 377           {
 378             if (INNER_THAN (1, 2))
 379               /* Stack grows down.  */
 380               sp = gdbarch_frame_align (current_gdbarch, old_sp - 1);
 381             else
 382               /* Stack grows up.  */
 383               sp = gdbarch_frame_align (current_gdbarch, old_sp + 1);
 384           }
 385         gdb_assert ((INNER_THAN (1, 2) && sp <= old_sp)
 386                     || (INNER_THAN (2, 1) && sp >= old_sp));
 387       }
 388     else
 389       /* FIXME: cagney/2002-09-18: Hey, you loose!
 390
 391          Who knows how badly aligned the SP is!
 392
 393          If the generic dummy frame ends up empty (because nothing is
 394          pushed) GDB won't be able to correctly perform back traces.
 395          If a target is having trouble with backtraces, first thing to
 396          do is add FRAME_ALIGN() to the architecture vector. If that
 397          fails, try unwind_dummy_id().
 398
 399          If the ABI specifies a "Red Zone" (see the doco) the code
 400          below will quietly trash it.  */
 401       sp = old_sp;
 402   }
 403
 404   funaddr = find_function_addr (function, &values_type);
 405   CHECK_TYPEDEF (values_type);
 406
 407   {
 408     struct block *b = block_for_pc (funaddr);
 409     /* If compiled without -g, assume GCC 2.  */
 410     using_gcc = (b == NULL ? 2 : BLOCK_GCC_COMPILED (b));
 411   }
 412
 413   /* Are we returning a value using a structure return or a normal
 414      value return? */
 415
 416   struct_return = using_struct_return (values_type, using_gcc);
 417
 418   /* Determine the location of the breakpoint (and possibly other
 419      stuff) that the called function will return to.  The SPARC, for a
 420      function returning a structure or union, needs to make space for
 421      not just the breakpoint but also an extra word containing the
 422      size (?) of the structure being passed.  */
 423
 424   /* The actual breakpoint (at BP_ADDR) is inserted separatly so there
 425      is no need to write that out.  */
 426
 427   switch (CALL_DUMMY_LOCATION)
 428     {
 429     case ON_STACK:
 430       /* "dummy_addr" is here just to keep old targets happy.  New
 431          targets return that same information via "sp" and "bp_addr".  */
 432       if (INNER_THAN (1, 2))
 433         {
 434           sp = push_dummy_code (current_gdbarch, sp, funaddr,
 435                                 using_gcc, args, nargs, values_type,
 436                                 &real_pc, &bp_addr);
 437           dummy_addr = sp;
 438         }
 439       else
 440         {
 441           dummy_addr = sp;
 442           sp = push_dummy_code (current_gdbarch, sp, funaddr,
 443                                 using_gcc, args, nargs, values_type,
 444                                 &real_pc, &bp_addr);
 445         }
 446       break;
 447     case AT_ENTRY_POINT:
 448       real_pc = funaddr;
 449       dummy_addr = entry_point_address ();
 450       /* Make certain that the address points at real code, and not a
 451          function descriptor.  */
 452       dummy_addr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 453                                                        dummy_addr,
 454                                                        &current_target);
 455       /* A call dummy always consists of just a single breakpoint, so
 456          it's address is the same as the address of the dummy.  */
 457       bp_addr = dummy_addr;
 458       break;
 459     case AT_SYMBOL:
 460       /* Some executables define a symbol __CALL_DUMMY_ADDRESS whose
 461          address is the location where the breakpoint should be
 462          placed.  Once all targets are using the overhauled frame code
 463          this can be deleted - ON_STACK is a better option.  */
 464       {
 465         struct minimal_symbol *sym;
 466
 467         sym = lookup_minimal_symbol ("__CALL_DUMMY_ADDRESS", NULL, NULL);
 468         real_pc = funaddr;
 469         if (sym)
 470           dummy_addr = SYMBOL_VALUE_ADDRESS (sym);
 471         else
 472           dummy_addr = entry_point_address ();
 473         /* Make certain that the address points at real code, and not
 474            a function descriptor.  */
 475         dummy_addr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 476                                                          dummy_addr,
 477                                                          &current_target);
 478         /* A call dummy always consists of just a single breakpoint,
 479            so it's address is the same as the address of the dummy.  */
 480         bp_addr = dummy_addr;
 481         break;
 482       }
 483     default:
 484       internal_error (__FILE__, __LINE__, _("bad switch"));
 485     }
 486
 487   if (nargs < TYPE_NFIELDS (ftype))
 488     error (_("too few arguments in function call"));
 489
 490   {
 491     int i;
 492     for (i = nargs - 1; i >= 0; i--)
 493       {
 494         int prototyped;
 495         struct type *param_type;
 496
 497         /* FIXME drow/2002-05-31: Should just always mark methods as
 498            prototyped.  Can we respect TYPE_VARARGS?  Probably not.  */
 499         if (TYPE_CODE (ftype) == TYPE_CODE_METHOD)
 500           prototyped = 1;
 501         else if (i < TYPE_NFIELDS (ftype))
 502           prototyped = TYPE_PROTOTYPED (ftype);
 503         else
 504           prototyped = 0;
 505
 506         if (i < TYPE_NFIELDS (ftype))
 507           param_type = TYPE_FIELD_TYPE (ftype, i);
 508         else
 509           param_type = NULL;
 510
 511         args[i] = value_arg_coerce (args[i], param_type, prototyped);
 512
 513         /* elz: this code is to handle the case in which the function
 514            to be called has a pointer to function as parameter and the
 515            corresponding actual argument is the address of a function
 516            and not a pointer to function variable.  In aCC compiled
 517            code, the calls through pointers to functions (in the body
 518            of the function called by hand) are made via
 519            $$dyncall_external which requires some registers setting,
 520            this is taken care of if we call via a function pointer
 521            variable, but not via a function address.  In cc this is
 522            not a problem. */
 523
 524         if (using_gcc == 0)
 525           {
 526             if (param_type != NULL && TYPE_CODE (ftype) != TYPE_CODE_METHOD)
 527               {
 528                 /* if this parameter is a pointer to function.  */
 529                 if (TYPE_CODE (param_type) == TYPE_CODE_PTR)
 530                   if (TYPE_CODE (TYPE_TARGET_TYPE (param_type)) == TYPE_CODE_FUNC)
 531                     /* elz: FIXME here should go the test about the
 532                        compiler used to compile the target. We want to
 533                        issue the error message only if the compiler
 534                        used was HP's aCC.  If we used HP's cc, then
 535                        there is no problem and no need to return at
 536                        this point.  */
 537                     /* Go see if the actual parameter is a variable of
 538                        type pointer to function or just a function.  */
 539                     if (VALUE_LVAL (args[i]) == not_lval)
 540                       {
 541                         char *arg_name;
 542                         /* NOTE: cagney/2005-01-02: THIS IS BOGUS.  */
 543                         if (find_pc_partial_function ((CORE_ADDR) value_contents (args[i])[0], &arg_name, NULL, NULL))
 544                           error (_("\
 545 You cannot use function <%s> as argument. \n\
 546 You must use a pointer to function type variable. Command ignored."), arg_name);
 547                       }
 548               }
 549           }
 550       }
 551   }
 552
 553   if (DEPRECATED_REG_STRUCT_HAS_ADDR_P ())
 554     {
 555       int i;
 556       /* This is a machine like the sparc, where we may need to pass a
 557          pointer to the structure, not the structure itself.  */
 558       for (i = nargs - 1; i >= 0; i--)
 559         {
 560           struct type *arg_type = check_typedef (value_type (args[i]));
 561           if ((TYPE_CODE (arg_type) == TYPE_CODE_STRUCT
 562                || TYPE_CODE (arg_type) == TYPE_CODE_UNION
 563                || TYPE_CODE (arg_type) == TYPE_CODE_ARRAY
 564                || TYPE_CODE (arg_type) == TYPE_CODE_STRING
 565                || TYPE_CODE (arg_type) == TYPE_CODE_BITSTRING
 566                || TYPE_CODE (arg_type) == TYPE_CODE_SET
 567                || (TYPE_CODE (arg_type) == TYPE_CODE_FLT
 568                    && TYPE_LENGTH (arg_type) > 8)
 569                )
 570               && DEPRECATED_REG_STRUCT_HAS_ADDR (using_gcc, arg_type))
 571             {
 572               CORE_ADDR addr;
 573               int len;          /*  = TYPE_LENGTH (arg_type); */
 574               int aligned_len;
 575               arg_type = check_typedef (value_enclosing_type (args[i]));
 576               len = TYPE_LENGTH (arg_type);
 577
 578               aligned_len = len;
 579               if (INNER_THAN (1, 2))
 580                 {
 581                   /* stack grows downward */
 582                   sp -= aligned_len;
 583                   /* ... so the address of the thing we push is the
 584                      stack pointer after we push it.  */
 585                   addr = sp;
 586                 }
 587               else
 588                 {
 589                   /* The stack grows up, so the address of the thing
 590                      we push is the stack pointer before we push it.  */
 591                   addr = sp;
 592                   sp += aligned_len;
 593                 }
 594               /* Push the structure.  */
 595               write_memory (addr, value_contents_all (args[i]), len);
 596               /* The value we're going to pass is the address of the
 597                  thing we just pushed.  */
 598               /*args[i] = value_from_longest (lookup_pointer_type (values_type),
 599                 (LONGEST) addr); */
 600               args[i] = value_from_pointer (lookup_pointer_type (arg_type),
 601                                             addr);
 602             }
 603         }
 604     }
 605
 606
 607   /* Reserve space for the return structure to be written on the
 608      stack, if necessary.  Make certain that the value is correctly
 609      aligned. */
 610
 611   if (struct_return)
 612     {
 613       int len = TYPE_LENGTH (values_type);
 614       if (INNER_THAN (1, 2))
 615         {
 616           /* Stack grows downward.  Align STRUCT_ADDR and SP after
 617              making space for the return value.  */
 618           sp -= len;
 619           if (gdbarch_frame_align_p (current_gdbarch))
 620             sp = gdbarch_frame_align (current_gdbarch, sp);
 621           struct_addr = sp;
 622         }
 623       else
 624         {
 625           /* Stack grows upward.  Align the frame, allocate space, and
 626              then again, re-align the frame??? */
 627           if (gdbarch_frame_align_p (current_gdbarch))
 628             sp = gdbarch_frame_align (current_gdbarch, sp);
 629           struct_addr = sp;
 630           sp += len;
 631           if (gdbarch_frame_align_p (current_gdbarch))
 632             sp = gdbarch_frame_align (current_gdbarch, sp);
 633         }
 634     }
 635
 636   /* Create the dummy stack frame.  Pass in the call dummy address as,
 637      presumably, the ABI code knows where, in the call dummy, the
 638      return address should be pointed.  */
 639   if (gdbarch_push_dummy_call_p (current_gdbarch))
 640     /* When there is no push_dummy_call method, should this code
 641        simply error out.  That would the implementation of this method
 642        for all ABIs (which is probably a good thing).  */
 643     sp = gdbarch_push_dummy_call (current_gdbarch, function, current_regcache,
 644                                   bp_addr, nargs, args, sp, struct_return,
 645                                   struct_addr);
 646   else  if (DEPRECATED_PUSH_ARGUMENTS_P ())
 647     /* Keep old targets working.  */
 648     sp = DEPRECATED_PUSH_ARGUMENTS (nargs, args, sp, struct_return,
 649                                     struct_addr);
 650   else
 651     error (_("This target does not support function calls"));
 652
 653   /* Set up a frame ID for the dummy frame so we can pass it to
 654      set_momentary_breakpoint.  We need to give the breakpoint a frame
 655      ID so that the breakpoint code can correctly re-identify the
 656      dummy breakpoint.  */
 657   /* Sanity.  The exact same SP value is returned by PUSH_DUMMY_CALL,
 658      saved as the dummy-frame TOS, and used by unwind_dummy_id to form
 659      the frame ID's stack address.  */
 660   dummy_id = frame_id_build (sp, bp_addr);
 661
 662   /* Create a momentary breakpoint at the return address of the
 663      inferior.  That way it breaks when it returns.  */
 664
 665   {
 666     struct breakpoint *bpt;
 667     struct symtab_and_line sal;
 668     init_sal (&sal);            /* initialize to zeroes */
 669     sal.pc = bp_addr;
 670     sal.section = find_pc_overlay (sal.pc);
 671     /* Sanity.  The exact same SP value is returned by
 672        PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by
 673        unwind_dummy_id to form the frame ID's stack address.  */
 674     bpt = set_momentary_breakpoint (sal, dummy_id, bp_call_dummy);
 675     bpt->disposition = disp_del;
 676   }
 677
 678   /* Everything's ready, push all the info needed to restore the
 679      caller (and identify the dummy-frame) onto the dummy-frame
 680      stack.  */
 681   dummy_frame_push (caller_regcache, &dummy_id);
 682   discard_cleanups (caller_regcache_cleanup);
 683
 684   /* - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP -
 685      If you're looking to implement asynchronous dummy-frames, then
 686      just below is the place to chop this function in two..  */
 687
 688   /* Now proceed, having reached the desired place.  */
 689   clear_proceed_status ();
 690
 691   /* Execute a "stack dummy", a piece of code stored in the stack by
 692      the debugger to be executed in the inferior.
 693
 694      The dummy's frame is automatically popped whenever that break is
 695      hit.  If that is the first time the program stops,
 696      call_function_by_hand returns to its caller with that frame
 697      already gone and sets RC to 0.
 698
 699      Otherwise, set RC to a non-zero value.  If the called function
 700      receives a random signal, we do not allow the user to continue
 701      executing it as this may not work.  The dummy frame is poped and
 702      we return 1.  If we hit a breakpoint, we leave the frame in place
 703      and return 2 (the frame will eventually be popped when we do hit
 704      the dummy end breakpoint).  */
 705
 706   {
 707     struct cleanup *old_cleanups = make_cleanup (null_cleanup, 0);
 708     int saved_async = 0;
 709
 710     /* If all error()s out of proceed ended up calling normal_stop
 711        (and perhaps they should; it already does in the special case
 712        of error out of resume()), then we wouldn't need this.  */
 713     make_cleanup (breakpoint_auto_delete_contents, &stop_bpstat);
 714
 715     disable_watchpoints_before_interactive_call_start ();
 716     proceed_to_finish = 1;      /* We want stop_registers, please... */
 717
 718     if (target_can_async_p ())
 719       saved_async = target_async_mask (0);
 720
 721     proceed (real_pc, TARGET_SIGNAL_0, 0);
 722
 723     if (saved_async)
 724       target_async_mask (saved_async);
 725
 726     enable_watchpoints_after_interactive_call_stop ();
 727
 728     discard_cleanups (old_cleanups);
 729   }
 730
 731   if (stopped_by_random_signal || !stop_stack_dummy)
 732     {
 733       /* Find the name of the function we're about to complain about.  */
 734       const char *name = NULL;
 735       {
 736         struct symbol *symbol = find_pc_function (funaddr);
 737         if (symbol)
 738           name = SYMBOL_PRINT_NAME (symbol);
 739         else
 740           {
 741             /* Try the minimal symbols.  */
 742             struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (funaddr);
 743             if (msymbol)
 744               name = SYMBOL_PRINT_NAME (msymbol);
 745           }
 746         if (name == NULL)
 747           {
 748             /* Can't use a cleanup here.  It is discarded, instead use
 749                an alloca.  */
 750             char *tmp = xstrprintf ("at %s", hex_string (funaddr));
 751             char *a = alloca (strlen (tmp) + 1);
 752             strcpy (a, tmp);
 753             xfree (tmp);
 754             name = a;
 755           }
 756       }
 757       if (stopped_by_random_signal)
 758         {
 759           /* We stopped inside the FUNCTION because of a random
 760              signal.  Further execution of the FUNCTION is not
 761              allowed. */
 762
 763           if (unwind_on_signal_p)
 764             {
 765               /* The user wants the context restored. */
 766
 767               /* We must get back to the frame we were before the
 768                  dummy call. */
 769               frame_pop (get_current_frame ());
 770
 771               /* FIXME: Insert a bunch of wrap_here; name can be very
 772                  long if it's a C++ name with arguments and stuff.  */
 773               error (_("\
 774 The program being debugged was signaled while in a function called from GDB.\n\
 775 GDB has restored the context to what it was before the call.\n\
 776 To change this behavior use \"set unwindonsignal off\"\n\
 777 Evaluation of the expression containing the function (%s) will be abandoned."),
 778                      name);
 779             }
 780           else
 781             {
 782               /* The user wants to stay in the frame where we stopped
 783                  (default).*/
 784               /* If we restored the inferior status (via the cleanup),
 785                  we would print a spurious error message (Unable to
 786                  restore previously selected frame), would write the
 787                  registers from the inf_status (which is wrong), and
 788                  would do other wrong things.  */
 789               discard_cleanups (inf_status_cleanup);
 790               discard_inferior_status (inf_status);
 791               /* FIXME: Insert a bunch of wrap_here; name can be very
 792                  long if it's a C++ name with arguments and stuff.  */
 793               error (_("\
 794 The program being debugged was signaled while in a function called from GDB.\n\
 795 GDB remains in the frame where the signal was received.\n\
 796 To change this behavior use \"set unwindonsignal on\"\n\
 797 Evaluation of the expression containing the function (%s) will be abandoned."),
 798                      name);
 799             }
 800         }
 801
 802       if (!stop_stack_dummy)
 803         {
 804           /* We hit a breakpoint inside the FUNCTION. */
 805           /* If we restored the inferior status (via the cleanup), we
 806              would print a spurious error message (Unable to restore
 807              previously selected frame), would write the registers
 808              from the inf_status (which is wrong), and would do other
 809              wrong things.  */
 810           discard_cleanups (inf_status_cleanup);
 811           discard_inferior_status (inf_status);
 812           /* The following error message used to say "The expression
 813              which contained the function call has been discarded."
 814              It is a hard concept to explain in a few words.  Ideally,
 815              GDB would be able to resume evaluation of the expression
 816              when the function finally is done executing.  Perhaps
 817              someday this will be implemented (it would not be easy).  */
 818           /* FIXME: Insert a bunch of wrap_here; name can be very long if it's
 819              a C++ name with arguments and stuff.  */
 820           error (_("\
 821 The program being debugged stopped while in a function called from GDB.\n\
 822 When the function (%s) is done executing, GDB will silently\n\
 823 stop (instead of continuing to evaluate the expression containing\n\
 824 the function call)."), name);
 825         }
 826
 827       /* The above code errors out, so ...  */
 828       internal_error (__FILE__, __LINE__, _("... should not be here"));
 829     }
 830
 831   /* If we get here the called FUNCTION run to completion. */
 832
 833   /* On normal return, the stack dummy has been popped already.  */
 834   regcache_cpy_no_passthrough (retbuf, stop_registers);
 835
 836   /* Restore the inferior status, via its cleanup.  At this stage,
 837      leave the RETBUF alone.  */
 838   do_cleanups (inf_status_cleanup);
 839
 840   /* Figure out the value returned by the function, return that.  */
 841   {
 842     struct value *retval;
 843     if (TYPE_CODE (values_type) == TYPE_CODE_VOID)
 844       /* If the function returns void, don't bother fetching the
 845          return value.  */
 846       retval = allocate_value (values_type);
 847     else if (struct_return)
 848       /* NOTE: cagney/2003-09-27: This assumes that PUSH_DUMMY_CALL
 849          has correctly stored STRUCT_ADDR in the target.  In the past
 850          that hasn't been the case, the old MIPS PUSH_ARGUMENTS
 851          (PUSH_DUMMY_CALL precursor) would silently move the location
 852          of the struct return value making STRUCT_ADDR bogus.  If
 853          you're seeing problems with values being returned using the
 854          "struct return convention", check that PUSH_DUMMY_CALL isn't
 855          playing tricks.  */
 856       retval = value_at (values_type, struct_addr);
 857     else
 858       {
 859         /* This code only handles "register convention".  */
 860         retval = allocate_value (values_type);
 861         gdb_assert (gdbarch_return_value (current_gdbarch, values_type,
 862                                           NULL, NULL, NULL)
 863                     == RETURN_VALUE_REGISTER_CONVENTION);
 864         gdbarch_return_value (current_gdbarch, values_type, retbuf,
 865                               value_contents_raw (retval) /*read*/,
 866                               NULL /*write*/);
 867       }
 868     do_cleanups (retbuf_cleanup);
 869     return retval;
 870   }
 871 }
 872
 873 void _initialize_infcall (void);
 874
 875 void
 876 _initialize_infcall (void)
 877 {
 878   add_setshow_boolean_cmd ("coerce-float-to-double", class_obscure,
 879                            &coerce_float_to_double_p, "\
 880 Set coercion of floats to doubles when calling functions.", "\
 881 Show coercion of floats to doubles when calling functions", "\
 882 Variables of type float should generally be converted to doubles before\n\
 883 calling an unprototyped function, and left alone when calling a prototyped\n\
 884 function.  However, some older debug info formats do not provide enough\n\
 885 information to determine that a function is prototyped.  If this flag is\n\
 886 set, GDB will perform the conversion for a function it considers\n\
 887 unprototyped.\n\
 888 The default is to perform the conversion.\n",
 889                            NULL, /* PRINT: Coercion of floats to doubles when calling functions is %s.  */
 890                            NULL, NULL, &setlist, &showlist);
 891
 892   add_setshow_boolean_cmd ("unwindonsignal", no_class,
 893                            &unwind_on_signal_p, "\
 894 Set unwinding of stack if a signal is received while in a call dummy.", "\
 895 Show unwinding of stack if a signal is received while in a call dummy.", "\
 896 The unwindonsignal lets the user determine what gdb should do if a signal\n\
 897 is received while in a function called from gdb (call dummy).  If set, gdb\n\
 898 unwinds the stack and restore the context to what as it was before the call.\n\
 899 The default is to stop in the frame where the signal was received.",
 900                            NULL, /* PRINT: Unwinding of stack if a signal is received while in a call dummy is %s.  */
 901                            NULL, NULL, &setlist, &showlist);
 902 }