contrib/gdb-6.2.1/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   if (retval_type != NULL)
 209     *retval_type = value_type;
 210   return funaddr + DEPRECATED_FUNCTION_START_OFFSET;
 211 }
 212
 213 /* Call breakpoint_auto_delete on the current contents of the bpstat
 214    pointed to by arg (which is really a bpstat *).  */
 215
 216 static void
 217 breakpoint_auto_delete_contents (void *arg)
 218 {
 219   breakpoint_auto_delete (*(bpstat *) arg);
 220 }
 221
 222 static CORE_ADDR
 223 generic_push_dummy_code (struct gdbarch *gdbarch,
 224                          CORE_ADDR sp, CORE_ADDR funaddr, int using_gcc,
 225                          struct value **args, int nargs,
 226                          struct type *value_type,
 227                          CORE_ADDR *real_pc, CORE_ADDR *bp_addr)
 228 {
 229   /* Something here to findout the size of a breakpoint and then
 230      allocate space for it on the stack.  */
 231   int bplen;
 232   /* This code assumes frame align.  */
 233   gdb_assert (gdbarch_frame_align_p (gdbarch));
 234   /* Force the stack's alignment.  The intent is to ensure that the SP
 235      is aligned to at least a breakpoint instruction's boundary.  */
 236   sp = gdbarch_frame_align (gdbarch, sp);
 237   /* Allocate space for, and then position the breakpoint on the
 238      stack.  */
 239   if (gdbarch_inner_than (gdbarch, 1, 2))
 240     {
 241       CORE_ADDR bppc = sp;
 242       gdbarch_breakpoint_from_pc (gdbarch, &bppc, &bplen);
 243       sp = gdbarch_frame_align (gdbarch, sp - bplen);
 244       (*bp_addr) = sp;
 245       /* Should the breakpoint size/location be re-computed here?  */
 246     }
 247   else
 248     {
 249       (*bp_addr) = sp;
 250       gdbarch_breakpoint_from_pc (gdbarch, bp_addr, &bplen);
 251       sp = gdbarch_frame_align (gdbarch, sp + bplen);
 252     }
 253   /* Inferior resumes at the function entry point.  */
 254   (*real_pc) = funaddr;
 255   return sp;
 256 }
 257
 258 /* For CALL_DUMMY_ON_STACK, push a breakpoint sequence that the called
 259    function returns to.  */
 260
 261 static CORE_ADDR
 262 push_dummy_code (struct gdbarch *gdbarch,
 263                  CORE_ADDR sp, CORE_ADDR funaddr, int using_gcc,
 264                  struct value **args, int nargs,
 265                  struct type *value_type,
 266                  CORE_ADDR *real_pc, CORE_ADDR *bp_addr)
 267 {
 268   if (gdbarch_push_dummy_code_p (gdbarch))
 269     return gdbarch_push_dummy_code (gdbarch, sp, funaddr, using_gcc,
 270                                     args, nargs, value_type, real_pc, bp_addr);
 271   else
 272     return generic_push_dummy_code (gdbarch, sp, funaddr, using_gcc,
 273                                     args, nargs, value_type, real_pc, bp_addr);
 274 }
 275
 276 /* All this stuff with a dummy frame may seem unnecessarily complicated
 277    (why not just save registers in GDB?).  The purpose of pushing a dummy
 278    frame which looks just like a real frame is so that if you call a
 279    function and then hit a breakpoint (get a signal, etc), "backtrace"
 280    will look right.  Whether the backtrace needs to actually show the
 281    stack at the time the inferior function was called is debatable, but
 282    it certainly needs to not display garbage.  So if you are contemplating
 283    making dummy frames be different from normal frames, consider that.  */
 284
 285 /* Perform a function call in the inferior.
 286    ARGS is a vector of values of arguments (NARGS of them).
 287    FUNCTION is a value, the function to be called.
 288    Returns a value representing what the function returned.
 289    May fail to return, if a breakpoint or signal is hit
 290    during the execution of the function.
 291
 292    ARGS is modified to contain coerced values. */
 293
 294 struct value *
 295 call_function_by_hand (struct value *function, int nargs, struct value **args)
 296 {
 297   CORE_ADDR sp;
 298   CORE_ADDR dummy_addr;
 299   struct type *value_type;
 300   unsigned char struct_return;
 301   CORE_ADDR struct_addr = 0;
 302   struct regcache *retbuf;
 303   struct cleanup *retbuf_cleanup;
 304   struct inferior_status *inf_status;
 305   struct cleanup *inf_status_cleanup;
 306   CORE_ADDR funaddr;
 307   int using_gcc;                /* Set to version of gcc in use, or zero if not gcc */
 308   CORE_ADDR real_pc;
 309   struct type *ftype = check_typedef (SYMBOL_TYPE (function));
 310   CORE_ADDR bp_addr;
 311
 312   if (!target_has_execution)
 313     noprocess ();
 314
 315   /* Create a cleanup chain that contains the retbuf (buffer
 316      containing the register values).  This chain is create BEFORE the
 317      inf_status chain so that the inferior status can cleaned up
 318      (restored or discarded) without having the retbuf freed.  */
 319   retbuf = regcache_xmalloc (current_gdbarch);
 320   retbuf_cleanup = make_cleanup_regcache_xfree (retbuf);
 321
 322   /* A cleanup for the inferior status.  Create this AFTER the retbuf
 323      so that this can be discarded or applied without interfering with
 324      the regbuf.  */
 325   inf_status = save_inferior_status (1);
 326   inf_status_cleanup = make_cleanup_restore_inferior_status (inf_status);
 327
 328   /* FIXME: cagney/2003-02-26: Step zero of this little tinker is to
 329      extract the generic dummy frame code from the architecture
 330      vector.  Hence this direct call.
 331
 332      A follow-on change is to modify this interface so that it takes
 333      thread OR frame OR ptid as a parameter, and returns a dummy frame
 334      handle.  The handle can then be used further down as a parameter
 335      to generic_save_dummy_frame_tos().  Hmm, thinking about it, since
 336      everything is ment to be using generic dummy frames, why not even
 337      use some of the dummy frame code to here - do a regcache dup and
 338      then pass the duped regcache, along with all the other stuff, at
 339      one single point.
 340
 341      In fact, you can even save the structure's return address in the
 342      dummy frame and fix one of those nasty lost struct return edge
 343      conditions.  */
 344   generic_push_dummy_frame ();
 345
 346   /* Ensure that the initial SP is correctly aligned.  */
 347   {
 348     CORE_ADDR old_sp = read_sp ();
 349     if (gdbarch_frame_align_p (current_gdbarch))
 350       {
 351         sp = gdbarch_frame_align (current_gdbarch, old_sp);
 352         /* NOTE: cagney/2003-08-13: Skip the "red zone".  For some
 353            ABIs, a function can use memory beyond the inner most stack
 354            address.  AMD64 called that region the "red zone".  Skip at
 355            least the "red zone" size before allocating any space on
 356            the stack.  */
 357         if (INNER_THAN (1, 2))
 358           sp -= gdbarch_frame_red_zone_size (current_gdbarch);
 359         else
 360           sp += gdbarch_frame_red_zone_size (current_gdbarch);
 361         /* Still aligned?  */
 362         gdb_assert (sp == gdbarch_frame_align (current_gdbarch, sp));
 363         /* NOTE: cagney/2002-09-18:
 364
 365            On a RISC architecture, a void parameterless generic dummy
 366            frame (i.e., no parameters, no result) typically does not
 367            need to push anything the stack and hence can leave SP and
 368            FP.  Similarly, a frameless (possibly leaf) function does
 369            not push anything on the stack and, hence, that too can
 370            leave FP and SP unchanged.  As a consequence, a sequence of
 371            void parameterless generic dummy frame calls to frameless
 372            functions will create a sequence of effectively identical
 373            frames (SP, FP and TOS and PC the same).  This, not
 374            suprisingly, results in what appears to be a stack in an
 375            infinite loop --- when GDB tries to find a generic dummy
 376            frame on the internal dummy frame stack, it will always
 377            find the first one.
 378
 379            To avoid this problem, the code below always grows the
 380            stack.  That way, two dummy frames can never be identical.
 381            It does burn a few bytes of stack but that is a small price
 382            to pay :-).  */
 383         if (sp == old_sp)
 384           {
 385             if (INNER_THAN (1, 2))
 386               /* Stack grows down.  */
 387               sp = gdbarch_frame_align (current_gdbarch, old_sp - 1);
 388             else
 389               /* Stack grows up.  */
 390               sp = gdbarch_frame_align (current_gdbarch, old_sp + 1);
 391           }
 392         gdb_assert ((INNER_THAN (1, 2) && sp <= old_sp)
 393                     || (INNER_THAN (2, 1) && sp >= old_sp));
 394       }
 395     else
 396       /* FIXME: cagney/2002-09-18: Hey, you loose!
 397
 398          Who knows how badly aligned the SP is!
 399
 400          If the generic dummy frame ends up empty (because nothing is
 401          pushed) GDB won't be able to correctly perform back traces.
 402          If a target is having trouble with backtraces, first thing to
 403          do is add FRAME_ALIGN() to the architecture vector. If that
 404          fails, try unwind_dummy_id().
 405
 406          If the ABI specifies a "Red Zone" (see the doco) the code
 407          below will quietly trash it.  */
 408       sp = old_sp;
 409   }
 410
 411   funaddr = find_function_addr (function, &value_type);
 412   CHECK_TYPEDEF (value_type);
 413
 414   {
 415     struct block *b = block_for_pc (funaddr);
 416     /* If compiled without -g, assume GCC 2.  */
 417     using_gcc = (b == NULL ? 2 : BLOCK_GCC_COMPILED (b));
 418   }
 419
 420   /* Are we returning a value using a structure return or a normal
 421      value return? */
 422
 423   struct_return = using_struct_return (value_type, using_gcc);
 424
 425   /* Determine the location of the breakpoint (and possibly other
 426      stuff) that the called function will return to.  The SPARC, for a
 427      function returning a structure or union, needs to make space for
 428      not just the breakpoint but also an extra word containing the
 429      size (?) of the structure being passed.  */
 430
 431   /* The actual breakpoint (at BP_ADDR) is inserted separatly so there
 432      is no need to write that out.  */
 433
 434   switch (CALL_DUMMY_LOCATION)
 435     {
 436     case ON_STACK:
 437       /* "dummy_addr" is here just to keep old targets happy.  New
 438          targets return that same information via "sp" and "bp_addr".  */
 439       if (INNER_THAN (1, 2))
 440         {
 441           sp = push_dummy_code (current_gdbarch, sp, funaddr,
 442                                 using_gcc, args, nargs, value_type,
 443                                 &real_pc, &bp_addr);
 444           dummy_addr = sp;
 445         }
 446       else
 447         {
 448           dummy_addr = sp;
 449           sp = push_dummy_code (current_gdbarch, sp, funaddr,
 450                                 using_gcc, args, nargs, value_type,
 451                                 &real_pc, &bp_addr);
 452         }
 453       break;
 454     case AT_ENTRY_POINT:
 455       real_pc = funaddr;
 456       dummy_addr = entry_point_address ();
 457       /* Make certain that the address points at real code, and not a
 458          function descriptor.  */
 459       dummy_addr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 460                                                        dummy_addr,
 461                                                        &current_target);
 462       /* A call dummy always consists of just a single breakpoint, so
 463          it's address is the same as the address of the dummy.  */
 464       bp_addr = dummy_addr;
 465       break;
 466     case AT_SYMBOL:
 467       /* Some executables define a symbol __CALL_DUMMY_ADDRESS whose
 468          address is the location where the breakpoint should be
 469          placed.  Once all targets are using the overhauled frame code
 470          this can be deleted - ON_STACK is a better option.  */
 471       {
 472         struct minimal_symbol *sym;
 473
 474         sym = lookup_minimal_symbol ("__CALL_DUMMY_ADDRESS", NULL, NULL);
 475         real_pc = funaddr;
 476         if (sym)
 477           dummy_addr = SYMBOL_VALUE_ADDRESS (sym);
 478         else
 479           dummy_addr = entry_point_address ();
 480         /* Make certain that the address points at real code, and not
 481            a function descriptor.  */
 482         dummy_addr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
 483                                                          dummy_addr,
 484                                                          &current_target);
 485         /* A call dummy always consists of just a single breakpoint,
 486            so it's address is the same as the address of the dummy.  */
 487         bp_addr = dummy_addr;
 488         break;
 489       }
 490     default:
 491       internal_error (__FILE__, __LINE__, "bad switch");
 492     }
 493
 494   /* Save where the breakpoint is going to be inserted so that the
 495      dummy-frame code is later able to re-identify it.  */
 496   generic_save_call_dummy_addr (bp_addr, bp_addr + 1);
 497
 498   if (nargs < TYPE_NFIELDS (ftype))
 499     error ("too few arguments in function call");
 500
 501   {
 502     int i;
 503     for (i = nargs - 1; i >= 0; i--)
 504       {
 505         int prototyped;
 506         struct type *param_type;
 507
 508         /* FIXME drow/2002-05-31: Should just always mark methods as
 509            prototyped.  Can we respect TYPE_VARARGS?  Probably not.  */
 510         if (TYPE_CODE (ftype) == TYPE_CODE_METHOD)
 511           prototyped = 1;
 512         else if (i < TYPE_NFIELDS (ftype))
 513           prototyped = TYPE_PROTOTYPED (ftype);
 514         else
 515           prototyped = 0;
 516
 517         if (i < TYPE_NFIELDS (ftype))
 518           param_type = TYPE_FIELD_TYPE (ftype, i);
 519         else
 520           param_type = NULL;
 521
 522         args[i] = value_arg_coerce (args[i], param_type, prototyped);
 523
 524         /* elz: this code is to handle the case in which the function
 525            to be called has a pointer to function as parameter and the
 526            corresponding actual argument is the address of a function
 527            and not a pointer to function variable.  In aCC compiled
 528            code, the calls through pointers to functions (in the body
 529            of the function called by hand) are made via
 530            $$dyncall_external which requires some registers setting,
 531            this is taken care of if we call via a function pointer
 532            variable, but not via a function address.  In cc this is
 533            not a problem. */
 534
 535         if (using_gcc == 0)
 536           {
 537             if (param_type != NULL && TYPE_CODE (ftype) != TYPE_CODE_METHOD)
 538               {
 539                 /* if this parameter is a pointer to function.  */
 540                 if (TYPE_CODE (param_type) == TYPE_CODE_PTR)
 541                   if (TYPE_CODE (TYPE_TARGET_TYPE (param_type)) == TYPE_CODE_FUNC)
 542                     /* elz: FIXME here should go the test about the
 543                        compiler used to compile the target. We want to
 544                        issue the error message only if the compiler
 545                        used was HP's aCC.  If we used HP's cc, then
 546                        there is no problem and no need to return at
 547                        this point.  */
 548                     /* Go see if the actual parameter is a variable of
 549                        type pointer to function or just a function.  */
 550                     if (args[i]->lval == not_lval)
 551                       {
 552                         char *arg_name;
 553                         if (find_pc_partial_function ((CORE_ADDR) args[i]->aligner.contents[0], &arg_name, NULL, NULL))
 554                           error ("\
 555 You cannot use function <%s> as argument. \n\
 556 You must use a pointer to function type variable. Command ignored.", arg_name);
 557                       }
 558               }
 559           }
 560       }
 561   }
 562
 563   if (DEPRECATED_REG_STRUCT_HAS_ADDR_P ())
 564     {
 565       int i;
 566       /* This is a machine like the sparc, where we may need to pass a
 567          pointer to the structure, not the structure itself.  */
 568       for (i = nargs - 1; i >= 0; i--)
 569         {
 570           struct type *arg_type = check_typedef (VALUE_TYPE (args[i]));
 571           if ((TYPE_CODE (arg_type) == TYPE_CODE_STRUCT
 572                || TYPE_CODE (arg_type) == TYPE_CODE_UNION
 573                || TYPE_CODE (arg_type) == TYPE_CODE_ARRAY
 574                || TYPE_CODE (arg_type) == TYPE_CODE_STRING
 575                || TYPE_CODE (arg_type) == TYPE_CODE_BITSTRING
 576                || TYPE_CODE (arg_type) == TYPE_CODE_SET
 577                || (TYPE_CODE (arg_type) == TYPE_CODE_FLT
 578                    && TYPE_LENGTH (arg_type) > 8)
 579                )
 580               && DEPRECATED_REG_STRUCT_HAS_ADDR (using_gcc, arg_type))
 581             {
 582               CORE_ADDR addr;
 583               int len;          /*  = TYPE_LENGTH (arg_type); */
 584               int aligned_len;
 585               arg_type = check_typedef (VALUE_ENCLOSING_TYPE (args[i]));
 586               len = TYPE_LENGTH (arg_type);
 587
 588               if (DEPRECATED_STACK_ALIGN_P ())
 589                 /* MVS 11/22/96: I think at least some of this
 590                    stack_align code is really broken.  Better to let
 591                    PUSH_ARGUMENTS adjust the stack in a target-defined
 592                    manner.  */
 593                 aligned_len = DEPRECATED_STACK_ALIGN (len);
 594               else
 595                 aligned_len = len;
 596               if (INNER_THAN (1, 2))
 597                 {
 598                   /* stack grows downward */
 599                   sp -= aligned_len;
 600                   /* ... so the address of the thing we push is the
 601                      stack pointer after we push it.  */
 602                   addr = sp;
 603                 }
 604               else
 605                 {
 606                   /* The stack grows up, so the address of the thing
 607                      we push is the stack pointer before we push it.  */
 608                   addr = sp;
 609                   sp += aligned_len;
 610                 }
 611               /* Push the structure.  */
 612               write_memory (addr, VALUE_CONTENTS_ALL (args[i]), len);
 613               /* The value we're going to pass is the address of the
 614                  thing we just pushed.  */
 615               /*args[i] = value_from_longest (lookup_pointer_type (value_type),
 616                 (LONGEST) addr); */
 617               args[i] = value_from_pointer (lookup_pointer_type (arg_type),
 618                                             addr);
 619             }
 620         }
 621     }
 622
 623
 624   /* Reserve space for the return structure to be written on the
 625      stack, if necessary.  Make certain that the value is correctly
 626      aligned. */
 627
 628   if (struct_return)
 629     {
 630       int len = TYPE_LENGTH (value_type);
 631       if (DEPRECATED_STACK_ALIGN_P ())
 632         /* NOTE: cagney/2003-03-22: Should rely on frame align, rather
 633            than stack align to force the alignment of the stack.  */
 634         len = DEPRECATED_STACK_ALIGN (len);
 635       if (INNER_THAN (1, 2))
 636         {
 637           /* Stack grows downward.  Align STRUCT_ADDR and SP after
 638              making space for the return value.  */
 639           sp -= len;
 640           if (gdbarch_frame_align_p (current_gdbarch))
 641             sp = gdbarch_frame_align (current_gdbarch, sp);
 642           struct_addr = sp;
 643         }
 644       else
 645         {
 646           /* Stack grows upward.  Align the frame, allocate space, and
 647              then again, re-align the frame??? */
 648           if (gdbarch_frame_align_p (current_gdbarch))
 649             sp = gdbarch_frame_align (current_gdbarch, sp);
 650           struct_addr = sp;
 651           sp += len;
 652           if (gdbarch_frame_align_p (current_gdbarch))
 653             sp = gdbarch_frame_align (current_gdbarch, sp);
 654         }
 655     }
 656
 657   /* Create the dummy stack frame.  Pass in the call dummy address as,
 658      presumably, the ABI code knows where, in the call dummy, the
 659      return address should be pointed.  */
 660   if (gdbarch_push_dummy_call_p (current_gdbarch))
 661     /* When there is no push_dummy_call method, should this code
 662        simply error out.  That would the implementation of this method
 663        for all ABIs (which is probably a good thing).  */
 664     sp = gdbarch_push_dummy_call (current_gdbarch, function, current_regcache,
 665                                   bp_addr, nargs, args, sp, struct_return,
 666                                   struct_addr);
 667   else  if (DEPRECATED_PUSH_ARGUMENTS_P ())
 668     /* Keep old targets working.  */
 669     sp = DEPRECATED_PUSH_ARGUMENTS (nargs, args, sp, struct_return,
 670                                     struct_addr);
 671   else
 672     error ("This target does not support function calls");
 673
 674   if (DEPRECATED_PUSH_RETURN_ADDRESS_P ())
 675     /* for targets that use no CALL_DUMMY */
 676     /* There are a number of targets now which actually don't write
 677        any CALL_DUMMY instructions into the target, but instead just
 678        save the machine state, push the arguments, and jump directly
 679        to the callee function.  Since this doesn't actually involve
 680        executing a JSR/BSR instruction, the return address must be set
 681        up by hand, either by pushing onto the stack or copying into a
 682        return-address register as appropriate.  Formerly this has been
 683        done in PUSH_ARGUMENTS, but that's overloading its
 684        functionality a bit, so I'm making it explicit to do it here.  */
 685     /* NOTE: cagney/2003-04-22: The first parameter ("real_pc") has
 686        been replaced with zero, it turns out that no implementation
 687        used that parameter.  This occured because the value being
 688        supplied - the address of the called function's entry point
 689        instead of the address of the breakpoint that the called
 690        function should return to - wasn't useful.  */
 691     sp = DEPRECATED_PUSH_RETURN_ADDRESS (0, sp);
 692
 693   /* NOTE: cagney/2003-03-23: Diable this code when there is a
 694      push_dummy_call() method.  Since that method will have already
 695      handled any alignment issues, the code below is entirely
 696      redundant.  */
 697   if (!gdbarch_push_dummy_call_p (current_gdbarch)
 698       && DEPRECATED_STACK_ALIGN_P () && !INNER_THAN (1, 2))
 699     {
 700       /* If stack grows up, we must leave a hole at the bottom, note
 701          that sp already has been advanced for the arguments!  */
 702       sp = DEPRECATED_STACK_ALIGN (sp);
 703     }
 704
 705   /* Store the address at which the structure is supposed to be
 706      written.  */
 707   /* NOTE: 2003-03-24: Since PUSH_ARGUMENTS can (and typically does)
 708      store the struct return address, this call is entirely redundant.  */
 709   if (struct_return && DEPRECATED_STORE_STRUCT_RETURN_P ())
 710     DEPRECATED_STORE_STRUCT_RETURN (struct_addr, sp);
 711
 712   /* Write the stack pointer.  This is here because the statements
 713      above might fool with it.  On SPARC, this write also stores the
 714      register window into the right place in the new stack frame,
 715      which otherwise wouldn't happen (see store_inferior_registers in
 716      sparc-nat.c).  */
 717   /* NOTE: cagney/2003-03-23: Since the architecture method
 718      push_dummy_call() should have already stored the stack pointer
 719      (as part of creating the fake call frame), and none of the code
 720      following that call adjusts the stack-pointer value, the below
 721      call is entirely redundant.  */
 722   if (DEPRECATED_DUMMY_WRITE_SP_P ())
 723     DEPRECATED_DUMMY_WRITE_SP (sp);
 724
 725   if (DEPRECATED_SAVE_DUMMY_FRAME_TOS_P ())
 726     DEPRECATED_SAVE_DUMMY_FRAME_TOS (sp);
 727   else
 728     /* Sanity.  The exact same SP value is returned by
 729        PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by
 730        unwind_dummy_id to form the frame ID's stack address.  */
 731     generic_save_dummy_frame_tos (sp);
 732
 733   /* Now proceed, having reached the desired place.  */
 734   clear_proceed_status ();
 735
 736   /* Create a momentary breakpoint at the return address of the
 737      inferior.  That way it breaks when it returns.  */
 738
 739   {
 740     struct breakpoint *bpt;
 741     struct symtab_and_line sal;
 742     struct frame_id frame;
 743     init_sal (&sal);            /* initialize to zeroes */
 744     sal.pc = bp_addr;
 745     sal.section = find_pc_overlay (sal.pc);
 746     /* Set up a frame ID for the dummy frame so we can pass it to
 747        set_momentary_breakpoint.  We need to give the breakpoint a
 748        frame ID so that the breakpoint code can correctly re-identify
 749        the dummy breakpoint.  */
 750     if (gdbarch_unwind_dummy_id_p (current_gdbarch))
 751       {
 752         /* Sanity.  The exact same SP value is returned by
 753          PUSH_DUMMY_CALL, saved as the dummy-frame TOS, and used by
 754          unwind_dummy_id to form the frame ID's stack address.  */
 755         frame = frame_id_build (sp, sal.pc);
 756       }
 757     else
 758       {
 759         /* The assumption here is that push_dummy_call() returned the
 760            stack part of the frame ID.  Unfortunately, many older
 761            architectures were, via a convoluted mess, relying on the
 762            poorly defined and greatly overloaded
 763            DEPRECATED_TARGET_READ_FP or DEPRECATED_FP_REGNUM to supply
 764            the value.  */
 765         if (DEPRECATED_TARGET_READ_FP_P ())
 766           frame = frame_id_build (DEPRECATED_TARGET_READ_FP (), sal.pc);
 767         else if (DEPRECATED_FP_REGNUM >= 0)
 768           frame = frame_id_build (read_register (DEPRECATED_FP_REGNUM), sal.pc);
 769         else
 770           frame = frame_id_build (sp, sal.pc);
 771       }
 772     bpt = set_momentary_breakpoint (sal, frame, bp_call_dummy);
 773     bpt->disposition = disp_del;
 774   }
 775
 776   /* Execute a "stack dummy", a piece of code stored in the stack by
 777      the debugger to be executed in the inferior.
 778
 779      The dummy's frame is automatically popped whenever that break is
 780      hit.  If that is the first time the program stops,
 781      call_function_by_hand returns to its caller with that frame
 782      already gone and sets RC to 0.
 783
 784      Otherwise, set RC to a non-zero value.  If the called function
 785      receives a random signal, we do not allow the user to continue
 786      executing it as this may not work.  The dummy frame is poped and
 787      we return 1.  If we hit a breakpoint, we leave the frame in place
 788      and return 2 (the frame will eventually be popped when we do hit
 789      the dummy end breakpoint).  */
 790
 791   {
 792     struct cleanup *old_cleanups = make_cleanup (null_cleanup, 0);
 793     int saved_async = 0;
 794
 795     /* If all error()s out of proceed ended up calling normal_stop
 796        (and perhaps they should; it already does in the special case
 797        of error out of resume()), then we wouldn't need this.  */
 798     make_cleanup (breakpoint_auto_delete_contents, &stop_bpstat);
 799
 800     disable_watchpoints_before_interactive_call_start ();
 801     proceed_to_finish = 1;      /* We want stop_registers, please... */
 802
 803     if (target_can_async_p ())
 804       saved_async = target_async_mask (0);
 805
 806     proceed (real_pc, TARGET_SIGNAL_0, 0);
 807
 808     if (saved_async)
 809       target_async_mask (saved_async);
 810
 811     enable_watchpoints_after_interactive_call_stop ();
 812
 813     discard_cleanups (old_cleanups);
 814   }
 815
 816   if (stopped_by_random_signal || !stop_stack_dummy)
 817     {
 818       /* Find the name of the function we're about to complain about.  */
 819       const char *name = NULL;
 820       {
 821         struct symbol *symbol = find_pc_function (funaddr);
 822         if (symbol)
 823           name = SYMBOL_PRINT_NAME (symbol);
 824         else
 825           {
 826             /* Try the minimal symbols.  */
 827             struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (funaddr);
 828             if (msymbol)
 829               name = SYMBOL_PRINT_NAME (msymbol);
 830           }
 831         if (name == NULL)
 832           {
 833             /* Can't use a cleanup here.  It is discarded, instead use
 834                an alloca.  */
 835             char *tmp = xstrprintf ("at %s", local_hex_string (funaddr));
 836             char *a = alloca (strlen (tmp) + 1);
 837             strcpy (a, tmp);
 838             xfree (tmp);
 839             name = a;
 840           }
 841       }
 842       if (stopped_by_random_signal)
 843         {
 844           /* We stopped inside the FUNCTION because of a random
 845              signal.  Further execution of the FUNCTION is not
 846              allowed. */
 847
 848           if (unwind_on_signal_p)
 849             {
 850               /* The user wants the context restored. */
 851
 852               /* We must get back to the frame we were before the
 853                  dummy call. */
 854               frame_pop (get_current_frame ());
 855
 856               /* FIXME: Insert a bunch of wrap_here; name can be very
 857                  long if it's a C++ name with arguments and stuff.  */
 858               error ("\
 859 The program being debugged was signaled while in a function called from GDB.\n\
 860 GDB has restored the context to what it was before the call.\n\
 861 To change this behavior use \"set unwindonsignal off\"\n\
 862 Evaluation of the expression containing the function (%s) will be abandoned.",
 863                      name);
 864             }
 865           else
 866             {
 867               /* The user wants to stay in the frame where we stopped
 868                  (default).*/
 869               /* If we restored the inferior status (via the cleanup),
 870                  we would print a spurious error message (Unable to
 871                  restore previously selected frame), would write the
 872                  registers from the inf_status (which is wrong), and
 873                  would do other wrong things.  */
 874               discard_cleanups (inf_status_cleanup);
 875               discard_inferior_status (inf_status);
 876               /* FIXME: Insert a bunch of wrap_here; name can be very
 877                  long if it's a C++ name with arguments and stuff.  */
 878               error ("\
 879 The program being debugged was signaled while in a function called from GDB.\n\
 880 GDB remains in the frame where the signal was received.\n\
 881 To change this behavior use \"set unwindonsignal on\"\n\
 882 Evaluation of the expression containing the function (%s) will be abandoned.",
 883                      name);
 884             }
 885         }
 886
 887       if (!stop_stack_dummy)
 888         {
 889           /* We hit a breakpoint inside the FUNCTION. */
 890           /* If we restored the inferior status (via the cleanup), we
 891              would print a spurious error message (Unable to restore
 892              previously selected frame), would write the registers
 893              from the inf_status (which is wrong), and would do other
 894              wrong things.  */
 895           discard_cleanups (inf_status_cleanup);
 896           discard_inferior_status (inf_status);
 897           /* The following error message used to say "The expression
 898              which contained the function call has been discarded."
 899              It is a hard concept to explain in a few words.  Ideally,
 900              GDB would be able to resume evaluation of the expression
 901              when the function finally is done executing.  Perhaps
 902              someday this will be implemented (it would not be easy).  */
 903           /* FIXME: Insert a bunch of wrap_here; name can be very long if it's
 904              a C++ name with arguments and stuff.  */
 905           error ("\
 906 The program being debugged stopped while in a function called from GDB.\n\
 907 When the function (%s) is done executing, GDB will silently\n\
 908 stop (instead of continuing to evaluate the expression containing\n\
 909 the function call).", name);
 910         }
 911
 912       /* The above code errors out, so ...  */
 913       internal_error (__FILE__, __LINE__, "... should not be here");
 914     }
 915
 916   /* If we get here the called FUNCTION run to completion. */
 917
 918   /* On normal return, the stack dummy has been popped already.  */
 919   regcache_cpy_no_passthrough (retbuf, stop_registers);
 920
 921   /* Restore the inferior status, via its cleanup.  At this stage,
 922      leave the RETBUF alone.  */
 923   do_cleanups (inf_status_cleanup);
 924
 925   /* Figure out the value returned by the function, return that.  */
 926   {
 927     struct value *retval;
 928     if (TYPE_CODE (value_type) == TYPE_CODE_VOID)
 929       /* If the function returns void, don't bother fetching the
 930          return value.  */
 931       retval = allocate_value (value_type);
 932     else if (struct_return)
 933       /* NOTE: cagney/2003-09-27: This assumes that PUSH_DUMMY_CALL
 934          has correctly stored STRUCT_ADDR in the target.  In the past
 935          that hasn't been the case, the old MIPS PUSH_ARGUMENTS
 936          (PUSH_DUMMY_CALL precursor) would silently move the location
 937          of the struct return value making STRUCT_ADDR bogus.  If
 938          you're seeing problems with values being returned using the
 939          "struct return convention", check that PUSH_DUMMY_CALL isn't
 940          playing tricks.  */
 941       retval = value_at (value_type, struct_addr, NULL);
 942     else
 943       {
 944         /* This code only handles "register convention".  */
 945         retval = allocate_value (value_type);
 946         gdb_assert (gdbarch_return_value (current_gdbarch, value_type,
 947                                           NULL, NULL, NULL)
 948                     == RETURN_VALUE_REGISTER_CONVENTION);
 949         gdbarch_return_value (current_gdbarch, value_type, retbuf,
 950                               VALUE_CONTENTS_RAW (retval) /*read*/,
 951                               NULL /*write*/);
 952       }
 953     do_cleanups (retbuf_cleanup);
 954     return retval;
 955   }
 956 }
 957
 958 void _initialize_infcall (void);
 959
 960 void
 961 _initialize_infcall (void)
 962 {
 963   add_setshow_boolean_cmd ("coerce-float-to-double", class_obscure,
 964                            &coerce_float_to_double_p, "\
 965 Set coercion of floats to doubles when calling functions\n\
 966 Variables of type float should generally be converted to doubles before\n\
 967 calling an unprototyped function, and left alone when calling a prototyped\n\
 968 function.  However, some older debug info formats do not provide enough\n\
 969 information to determine that a function is prototyped.  If this flag is\n\
 970 set, GDB will perform the conversion for a function it considers\n\
 971 unprototyped.\n\
 972 The default is to perform the conversion.\n", "\
 973 Show coercion of floats to doubles when calling functions\n\
 974 Variables of type float should generally be converted to doubles before\n\
 975 calling an unprototyped function, and left alone when calling a prototyped\n\
 976 function.  However, some older debug info formats do not provide enough\n\
 977 information to determine that a function is prototyped.  If this flag is\n\
 978 set, GDB will perform the conversion for a function it considers\n\
 979 unprototyped.\n\
 980 The default is to perform the conversion.\n",
 981                            NULL, NULL, &setlist, &showlist);
 982
 983   add_setshow_boolean_cmd ("unwindonsignal", no_class,
 984                            &unwind_on_signal_p, "\
 985 Set unwinding of stack if a signal is received while in a call dummy.\n\
 986 The unwindonsignal lets the user determine what gdb should do if a signal\n\
 987 is received while in a function called from gdb (call dummy).  If set, gdb\n\
 988 unwinds the stack and restore the context to what as it was before the call.\n\
 989 The default is to stop in the frame where the signal was received.", "\
 990 Show unwinding of stack if a signal is received while in a call dummy.\n\
 991 The unwindonsignal lets the user determine what gdb should do if a signal\n\
 992 is received while in a function called from gdb (call dummy).  If set, gdb\n\
 993 unwinds the stack and restore the context to what as it was before the call.\n\
 994 The default is to stop in the frame where the signal was received.",
 995                            NULL, NULL, &setlist, &showlist);
 996 }