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
   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
  39 /* NOTE: cagney/2003-04-16: What's the future of this code?
  40
  41    GDB needs an asynchronous expression evaluator, that means an
  42    asynchronous inferior function call implementation, and that in
  43    turn means restructuring the code so that it is event driven.  */
  44
  45 /* How you should pass arguments to a function depends on whether it
  46    was defined in K&R style or prototype style.  If you define a
  47    function using the K&R syntax that takes a `float' argument, then
  48    callers must pass that argument as a `double'.  If you define the
  49    function using the prototype syntax, then you must pass the
  50    argument as a `float', with no promotion.
  51
  52    Unfortunately, on certain older platforms, the debug info doesn't
  53    indicate reliably how each function was defined.  A function type's
  54    TYPE_FLAG_PROTOTYPED flag may be clear, even if the function was
  55    defined in prototype style.  When calling a function whose
  56    TYPE_FLAG_PROTOTYPED flag is clear, GDB consults this flag to
  57    decide what to do.
  58
  59    For modern targets, it is proper to assume that, if the prototype
  60    flag is clear, that can be trusted: `float' arguments should be
  61    promoted to `double'.  For some older targets, if the prototype
  62    flag is clear, that doesn't tell us anything.  The default is to
  63    trust the debug information; the user can override this behavior
  64    with "set coerce-float-to-double 0".  */
  65
  66 static int coerce_float_to_double_p = 1;
  67
  68 /* This boolean tells what gdb should do if a signal is received while
  69    in a function called from gdb (call dummy).  If set, gdb unwinds
  70    the stack and restore the context to what as it was before the
  71    call.
  72
  73    The default is to stop in the frame where the signal was received. */
  74
  75 int unwind_on_signal_p = 0;
  76
  77 /* Perform the standard coercions that are specified
  78    for arguments to be passed to C functions.
  79
  80    If PARAM_TYPE is non-NULL, it is the expected parameter type.
  81    IS_PROTOTYPED is non-zero if the function declaration is prototyped.  */
  82
  83 static struct value *
  84 value_arg_coerce (struct value *arg, struct type *param_type,
  85                   int is_prototyped)
  86 {
  87   struct type *arg_type = check_typedef (VALUE_TYPE (arg));
  88   struct type *type
  89     = param_type ? check_typedef (param_type) : arg_type;
  90
  91   switch (TYPE_CODE (type))
  92     {
  93     case TYPE_CODE_REF:
  94       if (TYPE_CODE (arg_type) != TYPE_CODE_REF
  95           && TYPE_CODE (arg_type) != TYPE_CODE_PTR)
  96         {
  97           arg = value_addr (arg);
  98           VALUE_TYPE (arg) = param_type;
  99           return arg;
 100         }
 101       break;
 102     case TYPE_CODE_INT:
 103     case TYPE_CODE_CHAR:
 104     case TYPE_CODE_BOOL:
 105     case TYPE_CODE_ENUM:
 106       /* If we don't have a prototype, coerce to integer type if necessary.  */
 107       if (!is_prototyped)
 108         {
 109           if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_int))
 110             type = builtin_type_int;
 111         }
 112       /* Currently all target ABIs require at least the width of an integer
 113          type for an argument.  We may have to conditionalize the following
 114          type coercion for future targets.  */
 115       if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_int))
 116         type = builtin_type_int;
 117       break;
 118     case TYPE_CODE_FLT:
 119       if (!is_prototyped && coerce_float_to_double_p)
 120         {
 121           if (TYPE_LENGTH (type) < TYPE_LENGTH (builtin_type_double))
 122             type = builtin_type_double;
 123           else if (TYPE_LENGTH (type) > TYPE_LENGTH (builtin_type_double))
 124             type = builtin_type_long_double;
 125         }
 126       break;
 127     case TYPE_CODE_FUNC:
 128       type = lookup_pointer_type (type);
 129       break;
 130     case TYPE_CODE_ARRAY:
 131       /* Arrays are coerced to pointers to their first element, unless
 132          they are vectors, in which case we want to leave them alone,
 133          because they are passed by value.  */
 134       if (current_language->c_style_arrays)
 135         if (!TYPE_VECTOR (type))
 136           type = lookup_pointer_type (TYPE_TARGET_TYPE (type));
 137       break;
 138     case TYPE_CODE_UNDEF:
 139     case TYPE_CODE_PTR:
 140     case TYPE_CODE_STRUCT:
 141     case TYPE_CODE_UNION:
 142     case TYPE_CODE_VOID:
 143     case TYPE_CODE_SET:
 144     case TYPE_CODE_RANGE:
 145     case TYPE_CODE_STRING:
 146     case TYPE_CODE_BITSTRING:
 147     case TYPE_CODE_ERROR:
 148     case TYPE_CODE_MEMBER:
 149     case TYPE_CODE_METHOD:
 150     case TYPE_CODE_COMPLEX:
 151     default:
 152       break;
 153     }
 154
 155   return value_cast (type, arg);
 156 }
 157
 158 /* Determine a function's address and its return type from its value.
 159    Calls error() if the function is not valid for calling.  */
 160
 161 CORE_ADDR
 162 find_function_addr (struct value *function, struct type **retval_type)
 163 {
 164   struct type *ftype = check_typedef (VALUE_TYPE (function));
 165   enum type_code code = TYPE_CODE (ftype);
 166   struct type *value_type;
 167   CORE_ADDR funaddr;
 168
 169   /* If it's a member function, just look at the function
 170      part of it.  */
 171
 172   /* Determine address to call.  */
 173   if (code == TYPE_CODE_FUNC || code == TYPE_CODE_METHOD)
 174     {
 175       funaddr = VALUE_ADDRESS (function);
 176       value_type = TYPE_TARGET_TYPE (ftype);
 177     }
 178   else if (code == TYPE_CODE_PTR)
 179     {
 180       funaddr = value_as_address (function);
 181       ftype = check_typedef (TYPE_TARGET_TYPE (ftype));
 182       if (TYPE_CODE (ftype) == TYPE_CODE_FUNC
 183           || TYPE_CODE (ftype) == TYPE_CODE_METHOD)
 184         {
 185           funaddr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 186                                                         funaddr,
 187                                                         &current_target);
 188           value_type = TYPE_TARGET_TYPE (ftype);
 189         }
 190       else
 191         value_type = builtin_type_int;
 192     }
 193   else if (code == TYPE_CODE_INT)
 194     {
 195       /* Handle the case of functions lacking debugging info.
 196          Their values are characters since their addresses are char */
 197       if (TYPE_LENGTH (ftype) == 1)
 198         funaddr = value_as_address (value_addr (function));
 199       else
 200         /* Handle integer used as address of a function.  */
 201         funaddr = (CORE_ADDR) value_as_long (function);
 202
 203       value_type = builtin_type_int;
 204     }
 205   else
 206     error ("Invalid data type for function to be called.");
 207
 208   *retval_type = value_type;
 209   return funaddr + FUNCTION_START_OFFSET;
 210 }
 211
 212 /* Call breakpoint_auto_delete on the current contents of the bpstat
 213    pointed to by arg (which is really a bpstat *).  */
 214
 215 static void
 216 breakpoint_auto_delete_contents (void *arg)
 217 {
 218   breakpoint_auto_delete (*(bpstat *) arg);
 219 }
 220
 221 static CORE_ADDR
 222 generic_push_dummy_code (struct gdbarch *gdbarch,
 223                          CORE_ADDR sp, CORE_ADDR funaddr, int using_gcc,
 224                          struct value **args, int nargs,
 225                          struct type *value_type,
 226                          CORE_ADDR *real_pc, CORE_ADDR *bp_addr)
 227 {
 228   /* Something here to findout the size of a breakpoint and then
 229      allocate space for it on the stack.  */
 230   int bplen;
 231   /* This code assumes frame align.  */
 232   gdb_assert (gdbarch_frame_align_p (gdbarch));
 233   /* Force the stack's alignment.  The intent is to ensure that the SP
 234      is aligned to at least a breakpoint instruction's boundary.  */
 235   sp = gdbarch_frame_align (gdbarch, sp);
 236   /* Allocate space for, and then position the breakpoint on the
 237      stack.  */
 238   if (gdbarch_inner_than (gdbarch, 1, 2))
 239     {
 240       CORE_ADDR bppc = sp;
 241       gdbarch_breakpoint_from_pc (gdbarch, &bppc, &bplen);
 242       sp = gdbarch_frame_align (gdbarch, sp - bplen);
 243       (*bp_addr) = sp;
 244       /* Should the breakpoint size/location be re-computed here?  */
 245     }
 246   else
 247     {
 248       (*bp_addr) = sp;
 249       gdbarch_breakpoint_from_pc (gdbarch, bp_addr, &bplen);
 250       sp = gdbarch_frame_align (gdbarch, sp + bplen);
 251     }
 252   /* Inferior resumes at the function entry point.  */
 253   (*real_pc) = funaddr;
 254   return sp;
 255 }
 256
 257 /* For CALL_DUMMY_ON_STACK, push a breakpoint sequence that the called
 258    function returns to.  */
 259
 260 static CORE_ADDR
 261 push_dummy_code (struct gdbarch *gdbarch,
 262                  CORE_ADDR sp, CORE_ADDR funaddr, int using_gcc,
 263                  struct value **args, int nargs,
 264                  struct type *value_type,
 265                  CORE_ADDR *real_pc, CORE_ADDR *bp_addr)
 266 {
 267   if (gdbarch_push_dummy_code_p (gdbarch))
 268     return gdbarch_push_dummy_code (gdbarch, sp, funaddr, using_gcc,
 269                                     args, nargs, value_type, real_pc, bp_addr);
 270   else
 271     return generic_push_dummy_code (gdbarch, sp, funaddr, using_gcc,
 272                                     args, nargs, value_type, real_pc, bp_addr);
 273 }
 274
 275 /* All this stuff with a dummy frame may seem unnecessarily complicated
 276    (why not just save registers in GDB?).  The purpose of pushing a dummy
 277    frame which looks just like a real frame is so that if you call a
 278    function and then hit a breakpoint (get a signal, etc), "backtrace"
 279    will look right.  Whether the backtrace needs to actually show the
 280    stack at the time the inferior function was called is debatable, but
 281    it certainly needs to not display garbage.  So if you are contemplating
 282    making dummy frames be different from normal frames, consider that.  */
 283
 284 /* Perform a function call in the inferior.
 285    ARGS is a vector of values of arguments (NARGS of them).
 286    FUNCTION is a value, the function to be called.
 287    Returns a value representing what the function returned.
 288    May fail to return, if a breakpoint or signal is hit
 289    during the execution of the function.
 290
 291    ARGS is modified to contain coerced values. */
 292
 293 struct value *
 294 call_function_by_hand (struct value *function, int nargs, struct value **args)
 295 {
 296   CORE_ADDR sp;
 297   CORE_ADDR dummy_addr;
 298   struct type *value_type;
 299   unsigned char struct_return;
 300   CORE_ADDR struct_addr = 0;
 301   struct regcache *retbuf;
 302   struct cleanup *retbuf_cleanup;
 303   struct inferior_status *inf_status;
 304   struct cleanup *inf_status_cleanup;
 305   CORE_ADDR funaddr;
 306   int using_gcc;                /* Set to version of gcc in use, or zero if not gcc */
 307   CORE_ADDR real_pc;
 308   struct type *ftype = check_typedef (SYMBOL_TYPE (function));
 309   CORE_ADDR bp_addr;
 310
 311   if (!target_has_execution)
 312     noprocess ();
 313
 314   /* Create a cleanup chain that contains the retbuf (buffer
 315      containing the register values).  This chain is create BEFORE the
 316      inf_status chain so that the inferior status can cleaned up
 317      (restored or discarded) without having the retbuf freed.  */
 318   retbuf = regcache_xmalloc (current_gdbarch);
 319   retbuf_cleanup = make_cleanup_regcache_xfree (retbuf);
 320
 321   /* A cleanup for the inferior status.  Create this AFTER the retbuf
 322      so that this can be discarded or applied without interfering with
 323      the regbuf.  */
 324   inf_status = save_inferior_status (1);
 325   inf_status_cleanup = make_cleanup_restore_inferior_status (inf_status);
 326
 327   /* FIXME: cagney/2003-02-26: Step zero of this little tinker is to
 328      extract the generic dummy frame code from the architecture
 329      vector.  Hence this direct call.
 330
 331      A follow-on change is to modify this interface so that it takes
 332      thread OR frame OR ptid as a parameter, and returns a dummy frame
 333      handle.  The handle can then be used further down as a parameter
 334      to generic_save_dummy_frame_tos().  Hmm, thinking about it, since
 335      everything is ment to be using generic dummy frames, why not even
 336      use some of the dummy frame code to here - do a regcache dup and
 337      then pass the duped regcache, along with all the other stuff, at
 338      one single point.
 339
 340      In fact, you can even save the structure's return address in the
 341      dummy frame and fix one of those nasty lost struct return edge
 342      conditions.  */
 343   generic_push_dummy_frame ();
 344
 345   /* Ensure that the initial SP is correctly aligned.  */
 346   {
 347     CORE_ADDR old_sp = read_sp ();
 348     if (gdbarch_frame_align_p (current_gdbarch))
 349       {
 350         sp = gdbarch_frame_align (current_gdbarch, old_sp);
 351         /* NOTE: cagney/2003-08-13: Skip the "red zone".  For some
 352            ABIs, a function can use memory beyond the inner most stack
 353            address.  AMD64 called that region the "red zone".  Skip at
 354            least the "red zone" size before allocating any space on
 355            the stack.  */
 356         if (INNER_THAN (1, 2))
 357           sp -= gdbarch_frame_red_zone_size (current_gdbarch);
 358         else
 359           sp += gdbarch_frame_red_zone_size (current_gdbarch);
 360         /* Still aligned?  */
 361         gdb_assert (sp == gdbarch_frame_align (current_gdbarch, sp));
 362         /* NOTE: cagney/2002-09-18:
 363
 364            On a RISC architecture, a void parameterless generic dummy
 365            frame (i.e., no parameters, no result) typically does not
 366            need to push anything the stack and hence can leave SP and
 367            FP.  Similarly, a frameless (possibly leaf) function does
 368            not push anything on the stack and, hence, that too can
 369            leave FP and SP unchanged.  As a consequence, a sequence of
 370            void parameterless generic dummy frame calls to frameless
 371            functions will create a sequence of effectively identical
 372            frames (SP, FP and TOS and PC the same).  This, not
 373            suprisingly, results in what appears to be a stack in an
 374            infinite loop --- when GDB tries to find a generic dummy
 375            frame on the internal dummy frame stack, it will always
 376            find the first one.
 377
 378            To avoid this problem, the code below always grows the
 379            stack.  That way, two dummy frames can never be identical.
 380            It does burn a few bytes of stack but that is a small price
 381            to pay :-).  */
 382         if (sp == old_sp)
 383           {
 384             if (INNER_THAN (1, 2))
 385               /* Stack grows down.  */
 386               sp = gdbarch_frame_align (current_gdbarch, old_sp - 1);
 387             else
 388               /* Stack grows up.  */
 389               sp = gdbarch_frame_align (current_gdbarch, old_sp + 1);
 390           }
 391         gdb_assert ((INNER_THAN (1, 2) && sp <= old_sp)
 392                     || (INNER_THAN (2, 1) && sp >= old_sp));
 393       }
 394     else
 395       /* FIXME: cagney/2002-09-18: Hey, you loose!
 396
 397          Who knows how badly aligned the SP is!
 398
 399          If the generic dummy frame ends up empty (because nothing is
 400          pushed) GDB won't be able to correctly perform back traces.
 401          If a target is having trouble with backtraces, first thing to
 402          do is add FRAME_ALIGN() to the architecture vector. If that
 403          fails, try unwind_dummy_id().
 404
 405          If the ABI specifies a "Red Zone" (see the doco) the code
 406          below will quietly trash it.  */
 407       sp = old_sp;
 408   }
 409
 410   funaddr = find_function_addr (function, &value_type);
 411   CHECK_TYPEDEF (value_type);
 412
 413   {
 414     struct block *b = block_for_pc (funaddr);
 415     /* If compiled without -g, assume GCC 2.  */
 416     using_gcc = (b == NULL ? 2 : BLOCK_GCC_COMPILED (b));
 417   }
 418
 419   /* Are we returning a value using a structure return or a normal
 420      value return? */
 421
 422   struct_return = using_struct_return (value_type, using_gcc);
 423
 424   /* Determine the location of the breakpoint (and possibly other
 425      stuff) that the called function will return to.  The SPARC, for a
 426      function returning a structure or union, needs to make space for
 427      not just the breakpoint but also an extra word containing the
 428      size (?) of the structure being passed.  */
 429
 430   /* The actual breakpoint (at BP_ADDR) is inserted separatly so there
 431      is no need to write that out.  */
 432
 433   switch (CALL_DUMMY_LOCATION)
 434     {
 435     case ON_STACK:
 436       /* "dummy_addr" is here just to keep old targets happy.  New
 437          targets return that same information via "sp" and "bp_addr".  */
 438       if (INNER_THAN (1, 2))
 439         {
 440           sp = push_dummy_code (current_gdbarch, sp, funaddr,
 441                                 using_gcc, args, nargs, value_type,
 442                                 &real_pc, &bp_addr);
 443           dummy_addr = sp;
 444         }
 445       else
 446         {
 447           dummy_addr = sp;
 448           sp = push_dummy_code (current_gdbarch, sp, funaddr,
 449                                 using_gcc, args, nargs, value_type,
 450                                 &real_pc, &bp_addr);
 451         }
 452       break;
 453     case AT_ENTRY_POINT:
 454       real_pc = funaddr;
 455       dummy_addr = entry_point_address ();
 456       /* Make certain that the address points at real code, and not a
 457          function descriptor.  */
 458       dummy_addr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 459                                                        dummy_addr,
 460                                                        &current_target);
 461       /* A call dummy always consists of just a single breakpoint, so
 462          it's address is the same as the address of the dummy.  */
 463       bp_addr = dummy_addr;
 464       break;
 465     case AT_SYMBOL:
 466       /* Some executables define a symbol __CALL_DUMMY_ADDRESS whose
 467          address is the location where the breakpoint should be
 468          placed.  Once all targets are using the overhauled frame code
 469          this can be deleted - ON_STACK is a better option.  */
 470       {
 471         struct minimal_symbol *sym;
 472
 473         sym = lookup_minimal_symbol ("__CALL_DUMMY_ADDRESS", NULL, NULL);
 474         real_pc = funaddr;
 475         if (sym)
 476           dummy_addr = SYMBOL_VALUE_ADDRESS (sym);
 477         else
 478           dummy_addr = entry_point_address ();
 479         /* Make certain that the address points at real code, and not
 480            a function descriptor.  */
 481         dummy_addr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 482                                                          dummy_addr,
 483                                                          &current_target);
 484         /* A call dummy always consists of just a single breakpoint,
 485            so it's address is the same as the address of the dummy.  */
 486         bp_addr = dummy_addr;
 487         break;
 488       }
 489     default:
 490       internal_error (__FILE__, __LINE__, "bad switch");
 491     }
 492
 493   /* Save where the breakpoint is going to be inserted so that the
 494      dummy-frame code is later able to re-identify it.  */
 495   generic_save_call_dummy_addr (bp_addr, bp_addr + 1);
 496
 497   if (nargs < TYPE_NFIELDS (ftype))
 498     error ("too few arguments in function call");
 499
 500   {
 501     int i;
 502     for (i = nargs - 1; i >= 0; i--)
 503       {
 504         int prototyped;
 505         struct type *param_type;
 506
 507         /* FIXME drow/2002-05-31: Should just always mark methods as
 508            prototyped.  Can we respect TYPE_VARARGS?  Probably not.  */
 509         if (TYPE_CODE (ftype) == TYPE_CODE_METHOD)
 510           prototyped = 1;
 511         else if (i < TYPE_NFIELDS (ftype))
 512           prototyped = TYPE_PROTOTYPED (ftype);
 513         else
 514           prototyped = 0;
 515
 516         if (i < TYPE_NFIELDS (ftype))
 517           param_type = TYPE_FIELD_TYPE (ftype, i);
 518         else
 519           param_type = NULL;
 520
 521         args[i] = value_arg_coerce (args[i], param_type, prototyped);
 522
 523         /* elz: this code is to handle the case in which the function
 524            to be called has a pointer to function as parameter and the
 525            corresponding actual argument is the address of a function
 526            and not a pointer to function variable.  In aCC compiled
 527            code, the calls through pointers to functions (in the body
 528            of the function called by hand) are made via
 529            $$dyncall_external which requires some registers setting,
 530            this is taken care of if we call via a function pointer
 531            variable, but not via a function address.  In cc this is
 532            not a problem. */
 533
 534         if (using_gcc == 0)
 535           {
 536             if (param_type != NULL && TYPE_CODE (ftype) != TYPE_CODE_METHOD)
 537               {
 538                 /* if this parameter is a pointer to function.  */
 539                 if (TYPE_CODE (param_type) == TYPE_CODE_PTR)
 540                   if (TYPE_CODE (TYPE_TARGET_TYPE (param_type)) == TYPE_CODE_FUNC)
 541                     /* elz: FIXME here should go the test about the
 542                        compiler used to compile the target. We want to
 543                        issue the error message only if the compiler
 544                        used was HP's aCC.  If we used HP's cc, then
 545                        there is no problem and no need to return at
 546                        this point.  */
 547                     /* Go see if the actual parameter is a variable of
 548                        type pointer to function or just a function.  */
 549                     if (args[i]->lval == not_lval)
 550                       {
 551                         char *arg_name;
 552                         if (find_pc_partial_function ((CORE_ADDR) args[i]->aligner.contents[0], &arg_name, NULL, NULL))
 553                           error ("\
 554 You cannot use function <%s> as argument. \n\
 555 You must use a pointer to function type variable. Command ignored.", arg_name);
 556                       }
 557               }
 558           }
 559       }
 560   }
 561
 562   if (DEPRECATED_REG_STRUCT_HAS_ADDR_P ())
 563     {
 564       int i;
 565       /* This is a machine like the sparc, where we may need to pass a
 566          pointer to the structure, not the structure itself.  */
 567       for (i = nargs - 1; i >= 0; i--)
 568         {
 569           struct type *arg_type = check_typedef (VALUE_TYPE (args[i]));
 570           if ((TYPE_CODE (arg_type) == TYPE_CODE_STRUCT
 571                || TYPE_CODE (arg_type) == TYPE_CODE_UNION
 572                || TYPE_CODE (arg_type) == TYPE_CODE_ARRAY
 573                || TYPE_CODE (arg_type) == TYPE_CODE_STRING
 574                || TYPE_CODE (arg_type) == TYPE_CODE_BITSTRING
 575                || TYPE_CODE (arg_type) == TYPE_CODE_SET
 576                || (TYPE_CODE (arg_type) == TYPE_CODE_FLT
 577                    && TYPE_LENGTH (arg_type) > 8)
 578                )
 579               && DEPRECATED_REG_STRUCT_HAS_ADDR (using_gcc, arg_type))
 580             {
 581               CORE_ADDR addr;
 582               int len;          /*  = TYPE_LENGTH (arg_type); */
 583               int aligned_len;
 584               arg_type = check_typedef (VALUE_ENCLOSING_TYPE (args[i]));
 585               len = TYPE_LENGTH (arg_type);
 586
 587               if (DEPRECATED_STACK_ALIGN_P ())
 588                 /* MVS 11/22/96: I think at least some of this
 589                    stack_align code is really broken.  Better to let
 590                    PUSH_ARGUMENTS adjust the stack in a target-defined
 591                    manner.  */
 592                 aligned_len = DEPRECATED_STACK_ALIGN (len);
 593               else
 594                 aligned_len = len;
 595               if (INNER_THAN (1, 2))
 596                 {
 597                   /* stack grows downward */
 598                   sp -= aligned_len;
 599                   /* ... so the address of the thing we push is the
 600                      stack pointer after we push it.  */
 601                   addr = sp;
 602                 }
 603               else
 604                 {
 605                   /* The stack grows up, so the address of the thing
 606                      we push is the stack pointer before we push it.  */
 607                   addr = sp;
 608                   sp += aligned_len;
 609                 }
 610               /* Push the structure.  */
 611               write_memory (addr, VALUE_CONTENTS_ALL (args[i]), len);
 612               /* The value we're going to pass is the address of the
 613                  thing we just pushed.  */
 614               /*args[i] = value_from_longest (lookup_pointer_type (value_type),
 615                 (LONGEST) addr); */
 616               args[i] = value_from_pointer (lookup_pointer_type (arg_type),
 617                                             addr);
 618             }
 619         }
 620     }
 621
 622
 623   /* Reserve space for the return structure to be written on the
 624      stack, if necessary.  Make certain that the value is correctly
 625      aligned. */
 626
 627   if (struct_return)
 628     {
 629       int len = TYPE_LENGTH (value_type);
 630       if (DEPRECATED_STACK_ALIGN_P ())
 631         /* NOTE: cagney/2003-03-22: Should rely on frame align, rather
 632            than stack align to force the alignment of the stack.  */
 633         len = DEPRECATED_STACK_ALIGN (len);
 634       if (INNER_THAN (1, 2))
 635         {
 636           /* Stack grows downward.  Align STRUCT_ADDR and SP after
 637              making space for the return value.  */
 638           sp -= len;
 639           if (gdbarch_frame_align_p (current_gdbarch))
 640             sp = gdbarch_frame_align (current_gdbarch, sp);
 641           struct_addr = sp;
 642         }
 643       else
 644         {
 645           /* Stack grows upward.  Align the frame, allocate space, and
 646              then again, re-align the frame??? */
 647           if (gdbarch_frame_align_p (current_gdbarch))
 648             sp = gdbarch_frame_align (current_gdbarch, sp);
 649           struct_addr = sp;
 650           sp += len;
 651           if (gdbarch_frame_align_p (current_gdbarch))
 652             sp = gdbarch_frame_align (current_gdbarch, sp);
 653         }
 654     }
 655
 656   /* Create the dummy stack frame.  Pass in the call dummy address as,
 657      presumably, the ABI code knows where, in the call dummy, the
 658      return address should be pointed.  */
 659   if (gdbarch_push_dummy_call_p (current_gdbarch))
 660     /* When there is no push_dummy_call method, should this code
 661        simply error out.  That would the implementation of this method
 662        for all ABIs (which is probably a good thing).  */
 663     sp = gdbarch_push_dummy_call (current_gdbarch, funaddr, current_regcache,
 664                                   bp_addr, nargs, args, sp, struct_return,
 665                                   struct_addr);
 666   else  if (DEPRECATED_PUSH_ARGUMENTS_P ())
 667     /* Keep old targets working.  */
 668     sp = DEPRECATED_PUSH_ARGUMENTS (nargs, args, sp, struct_return,
 669                                     struct_addr);
 670   else
 671     sp = legacy_push_arguments (nargs, args, sp, struct_return, struct_addr);
 672
 673   if (DEPRECATED_PUSH_RETURN_ADDRESS_P ())
 674     /* for targets that use no CALL_DUMMY */
 675     /* There are a number of targets now which actually don't write
 676        any CALL_DUMMY instructions into the target, but instead just
 677        save the machine state, push the arguments, and jump directly
 678        to the callee function.  Since this doesn't actually involve
 679        executing a JSR/BSR instruction, the return address must be set
 680        up by hand, either by pushing onto the stack or copying into a
 681        return-address register as appropriate.  Formerly this has been
 682        done in PUSH_ARGUMENTS, but that's overloading its
 683        functionality a bit, so I'm making it explicit to do it here.  */
 684     /* NOTE: cagney/2003-04-22: The first parameter ("real_pc") has
 685        been replaced with zero, it turns out that no implementation
 686        used that parameter.  This occured because the value being
 687        supplied - the address of the called function's entry point
 688        instead of the address of the breakpoint that the called
 689        function should return to - wasn't useful.  */
 690     sp = DEPRECATED_PUSH_RETURN_ADDRESS (0, sp);
 691
 692   /* NOTE: cagney/2003-03-23: Diable this code when there is a
 693      push_dummy_call() method.  Since that method will have already
 694      handled any alignment issues, the code below is entirely
 695      redundant.  */
 696   if (!gdbarch_push_dummy_call_p (current_gdbarch)
 697       && DEPRECATED_STACK_ALIGN_P () && !INNER_THAN (1, 2))
 698     {
 699       /* If stack grows up, we must leave a hole at the bottom, note
 700          that sp already has been advanced for the arguments!  */
 701       sp = DEPRECATED_STACK_ALIGN (sp);
 702     }
 703
 704   /* Store the address at which the structure is supposed to be
 705      written.  */
 706   /* NOTE: 2003-03-24: Since PUSH_ARGUMENTS can (and typically does)
 707      store the struct return address, this call is entirely redundant.  */
 708   if (struct_return && DEPRECATED_STORE_STRUCT_RETURN_P ())
 709     DEPRECATED_STORE_STRUCT_RETURN (struct_addr, sp);
 710
 711   /* Write the stack pointer.  This is here because the statements
 712      above might fool with it.  On SPARC, this write also stores the
 713      register window into the right place in the new stack frame,
 714      which otherwise wouldn't happen (see store_inferior_registers in
 715      sparc-nat.c).  */
 716   /* NOTE: cagney/2003-03-23: Since the architecture method
 717      push_dummy_call() should have already stored the stack pointer
 718      (as part of creating the fake call frame), and none of the code
 719      following that call adjusts the stack-pointer value, the below
 720      call is entirely redundant.  */
 721   if (DEPRECATED_DUMMY_WRITE_SP_P ())
 722     DEPRECATED_DUMMY_WRITE_SP (sp);
 723
 724   if (gdbarch_unwind_dummy_id_p (current_gdbarch))
 725     {
 726       /* Sanity.  The exact same SP value is returned by
 727          PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by
 728          unwind_dummy_id to form the frame ID's stack address.  */
 729       generic_save_dummy_frame_tos (sp);
 730     }
 731   else if (DEPRECATED_SAVE_DUMMY_FRAME_TOS_P ())
 732     DEPRECATED_SAVE_DUMMY_FRAME_TOS (sp);
 733
 734   /* Now proceed, having reached the desired place.  */
 735   clear_proceed_status ();
 736
 737   /* Create a momentary breakpoint at the return address of the
 738      inferior.  That way it breaks when it returns.  */
 739
 740   {
 741     struct breakpoint *bpt;
 742     struct symtab_and_line sal;
 743     struct frame_id frame;
 744     init_sal (&sal);            /* initialize to zeroes */
 745     sal.pc = bp_addr;
 746     sal.section = find_pc_overlay (sal.pc);
 747     /* Set up a frame ID for the dummy frame so we can pass it to
 748        set_momentary_breakpoint.  We need to give the breakpoint a
 749        frame ID so that the breakpoint code can correctly re-identify
 750        the dummy breakpoint.  */
 751     if (gdbarch_unwind_dummy_id_p (current_gdbarch))
 752       {
 753         /* Sanity.  The exact same SP value is returned by
 754          PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by
 755          unwind_dummy_id to form the frame ID's stack address.  */
 756         frame = frame_id_build (sp, sal.pc);
 757       }
 758     else
 759       {
 760         /* The assumption here is that push_dummy_call() returned the
 761            stack part of the frame ID.  Unfortunately, many older
 762            architectures were, via a convoluted mess, relying on the
 763            poorly defined and greatly overloaded
 764            DEPRECATED_TARGET_READ_FP or DEPRECATED_FP_REGNUM to supply
 765            the value.  */
 766         if (DEPRECATED_TARGET_READ_FP_P ())
 767           frame = frame_id_build (DEPRECATED_TARGET_READ_FP (), sal.pc);
 768         else if (DEPRECATED_FP_REGNUM >= 0)
 769           frame = frame_id_build (read_register (DEPRECATED_FP_REGNUM), sal.pc);
 770         else
 771           frame = frame_id_build (sp, sal.pc);
 772       }
 773     bpt = set_momentary_breakpoint (sal, frame, bp_call_dummy);
 774     bpt->disposition = disp_del;
 775   }
 776
 777   /* Execute a "stack dummy", a piece of code stored in the stack by
 778      the debugger to be executed in the inferior.
 779
 780      The dummy's frame is automatically popped whenever that break is
 781      hit.  If that is the first time the program stops,
 782      call_function_by_hand returns to its caller with that frame
 783      already gone and sets RC to 0.
 784
 785      Otherwise, set RC to a non-zero value.  If the called function
 786      receives a random signal, we do not allow the user to continue
 787      executing it as this may not work.  The dummy frame is poped and
 788      we return 1.  If we hit a breakpoint, we leave the frame in place
 789      and return 2 (the frame will eventually be popped when we do hit
 790      the dummy end breakpoint).  */
 791
 792   {
 793     struct cleanup *old_cleanups = make_cleanup (null_cleanup, 0);
 794     int saved_async = 0;
 795
 796     /* If all error()s out of proceed ended up calling normal_stop
 797        (and perhaps they should; it already does in the special case
 798        of error out of resume()), then we wouldn't need this.  */
 799     make_cleanup (breakpoint_auto_delete_contents, &stop_bpstat);
 800
 801     disable_watchpoints_before_interactive_call_start ();
 802     proceed_to_finish = 1;      /* We want stop_registers, please... */
 803
 804     if (target_can_async_p ())
 805       saved_async = target_async_mask (0);
 806
 807     proceed (real_pc, TARGET_SIGNAL_0, 0);
 808
 809     if (saved_async)
 810       target_async_mask (saved_async);
 811
 812     enable_watchpoints_after_interactive_call_stop ();
 813
 814     discard_cleanups (old_cleanups);
 815   }
 816
 817   if (stopped_by_random_signal || !stop_stack_dummy)
 818     {
 819       /* Find the name of the function we're about to complain about.  */
 820       const char *name = NULL;
 821       {
 822         struct symbol *symbol = find_pc_function (funaddr);
 823         if (symbol)
 824           name = SYMBOL_PRINT_NAME (symbol);
 825         else
 826           {
 827             /* Try the minimal symbols.  */
 828             struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (funaddr);
 829             if (msymbol)
 830               name = SYMBOL_PRINT_NAME (msymbol);
 831           }
 832         if (name == NULL)
 833           {
 834             /* Can't use a cleanup here.  It is discarded, instead use
 835                an alloca.  */
 836             char *tmp = xstrprintf ("at %s", local_hex_string (funaddr));
 837             char *a = alloca (strlen (tmp) + 1);
 838             strcpy (a, tmp);
 839             xfree (tmp);
 840             name = a;
 841           }
 842       }
 843       if (stopped_by_random_signal)
 844         {
 845           /* We stopped inside the FUNCTION because of a random
 846              signal.  Further execution of the FUNCTION is not
 847              allowed. */
 848
 849           if (unwind_on_signal_p)
 850             {
 851               /* The user wants the context restored. */
 852
 853               /* We must get back to the frame we were before the
 854                  dummy call. */
 855               frame_pop (get_current_frame ());
 856
 857               /* FIXME: Insert a bunch of wrap_here; name can be very
 858                  long if it's a C++ name with arguments and stuff.  */
 859               error ("\
 860 The program being debugged was signaled while in a function called from GDB.\n\
 861 GDB has restored the context to what it was before the call.\n\
 862 To change this behavior use \"set unwindonsignal off\"\n\
 863 Evaluation of the expression containing the function (%s) will be abandoned.",
 864                      name);
 865             }
 866           else
 867             {
 868               /* The user wants to stay in the frame where we stopped
 869                  (default).*/
 870               /* If we restored the inferior status (via the cleanup),
 871                  we would print a spurious error message (Unable to
 872                  restore previously selected frame), would write the
 873                  registers from the inf_status (which is wrong), and
 874                  would do other wrong things.  */
 875               discard_cleanups (inf_status_cleanup);
 876               discard_inferior_status (inf_status);
 877               /* FIXME: Insert a bunch of wrap_here; name can be very
 878                  long if it's a C++ name with arguments and stuff.  */
 879               error ("\
 880 The program being debugged was signaled while in a function called from GDB.\n\
 881 GDB remains in the frame where the signal was received.\n\
 882 To change this behavior use \"set unwindonsignal on\"\n\
 883 Evaluation of the expression containing the function (%s) will be abandoned.",
 884                      name);
 885             }
 886         }
 887
 888       if (!stop_stack_dummy)
 889         {
 890           /* We hit a breakpoint inside the FUNCTION. */
 891           /* If we restored the inferior status (via the cleanup), we
 892              would print a spurious error message (Unable to restore
 893              previously selected frame), would write the registers
 894              from the inf_status (which is wrong), and would do other
 895              wrong things.  */
 896           discard_cleanups (inf_status_cleanup);
 897           discard_inferior_status (inf_status);
 898           /* The following error message used to say "The expression
 899              which contained the function call has been discarded."
 900              It is a hard concept to explain in a few words.  Ideally,
 901              GDB would be able to resume evaluation of the expression
 902              when the function finally is done executing.  Perhaps
 903              someday this will be implemented (it would not be easy).  */
 904           /* FIXME: Insert a bunch of wrap_here; name can be very long if it's
 905              a C++ name with arguments and stuff.  */
 906           error ("\
 907 The program being debugged stopped while in a function called from GDB.\n\
 908 When the function (%s) is done executing, GDB will silently\n\
 909 stop (instead of continuing to evaluate the expression containing\n\
 910 the function call).", name);
 911         }
 912
 913       /* The above code errors out, so ...  */
 914       internal_error (__FILE__, __LINE__, "... should not be here");
 915     }
 916
 917   /* If we get here the called FUNCTION run to completion. */
 918
 919   /* On normal return, the stack dummy has been popped already.  */
 920   regcache_cpy_no_passthrough (retbuf, stop_registers);
 921
 922   /* Restore the inferior status, via its cleanup.  At this stage,
 923      leave the RETBUF alone.  */
 924   do_cleanups (inf_status_cleanup);
 925
 926   /* Figure out the value returned by the function.  */
 927   if (struct_return)
 928     {
 929       /* NOTE: cagney/2003-09-27: This assumes that PUSH_DUMMY_CALL
 930          has correctly stored STRUCT_ADDR in the target.  In the past
 931          that hasn't been the case, the old MIPS PUSH_ARGUMENTS
 932          (PUSH_DUMMY_CALL precursor) would silently move the location
 933          of the struct return value making STRUCT_ADDR bogus.  If
 934          you're seeing problems with values being returned using the
 935          "struct return convention", check that PUSH_DUMMY_CALL isn't
 936          playing tricks.  */
 937       struct value *retval = value_at (value_type, struct_addr, NULL);
 938       do_cleanups (retbuf_cleanup);
 939       return retval;
 940     }
 941   else
 942     {
 943       /* The non-register case was handled above.  */
 944       struct value *retval = register_value_being_returned (value_type,
 945                                                             retbuf);
 946       do_cleanups (retbuf_cleanup);
 947       return retval;
 948     }
 949 }
 950
 951 void _initialize_infcall (void);
 952
 953 void
 954 _initialize_infcall (void)
 955 {
 956   add_setshow_boolean_cmd ("coerce-float-to-double", class_obscure,
 957                            &coerce_float_to_double_p, "\
 958 Set coercion of floats to doubles when calling functions\n\
 959 Variables of type float should generally be converted to doubles before\n\
 960 calling an unprototyped function, and left alone when calling a prototyped\n\
 961 function.  However, some older debug info formats do not provide enough\n\
 962 information to determine that a function is prototyped.  If this flag is\n\
 963 set, GDB will perform the conversion for a function it considers\n\
 964 unprototyped.\n\
 965 The default is to perform the conversion.\n", "\
 966 Show coercion of floats to doubles when calling functions\n\
 967 Variables of type float should generally be converted to doubles before\n\
 968 calling an unprototyped function, and left alone when calling a prototyped\n\
 969 function.  However, some older debug info formats do not provide enough\n\
 970 information to determine that a function is prototyped.  If this flag is\n\
 971 set, GDB will perform the conversion for a function it considers\n\
 972 unprototyped.\n\
 973 The default is to perform the conversion.\n",
 974                            NULL, NULL, &setlist, &showlist);
 975
 976   add_setshow_boolean_cmd ("unwindonsignal", no_class,
 977                            &unwind_on_signal_p, "\
 978 Set unwinding of stack if a signal is received while in a call dummy.\n\
 979 The unwindonsignal lets the user determine what gdb should do if a signal\n\
 980 is received while in a function called from gdb (call dummy).  If set, gdb\n\
 981 unwinds the stack and restore the context to what as it was before the call.\n\
 982 The default is to stop in the frame where the signal was received.", "\
 983 Show unwinding of stack if a signal is received while in a call dummy.\n\
 984 The unwindonsignal lets the user determine what gdb should do if a signal\n\
 985 is received while in a function called from gdb (call dummy).  If set, gdb\n\
 986 unwinds the stack and restore the context to what as it was before the call.\n\
 987 The default is to stop in the frame where the signal was received.",
 988                            NULL, NULL, &setlist, &showlist);
 989 }