gdb/tm-rs6000.h

   1 /* Parameters for target execution on an RS6000, for GDB, the GNU debugger.
   2    Copyright (C) 1986, 1987, 1989, 1991 Free Software Foundation, Inc.
   3    Contributed by IBM Corporation.
   4
   5 This file is part of GDB.
   6
   7 This program is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program; if not, write to the Free Software
  19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 extern int      symtab_relocated;
  22
  23 /* Minimum possible text address in AIX */
  24
  25 #define TEXT_SEGMENT_BASE       0x10000000
  26
  27
  28 /* text addresses in a core file does not necessarily match to symbol table,
  29    if symbol table relocation wasn't done yet. */
  30
  31 #define CORE_NEEDS_RELOCATION(PC)       \
  32   if (!symtab_relocated && !inferior_pid && (PC) >  TEXT_SEGMENT_BASE)  \
  33     (PC) -= ( TEXT_SEGMENT_BASE + text_adjustment (exec_bfd));
  34
  35 /* Load segment of a given pc value. */
  36
  37 #define PC_LOAD_SEGMENT(PC)     pc_load_segment_name(PC)
  38
  39 /* AIX cc seems to get this right.  */
  40
  41 #define BELIEVE_PCC_PROMOTION 1
  42
  43 /* Conversion between a register number in stab string to actual register num. */
  44
  45 #define STAB_REG_TO_REGNUM(value)       (value)
  46
  47 /* return true if a given `pc' value is in `call dummy' function. */
  48
  49 #define PC_IN_CALL_DUMMY(STOP_PC, STOP_SP, STOP_FRAME_ADDR)     \
  50         (STOP_SP < STOP_PC && STOP_PC < STACK_END_ADDR)
  51
  52 /* For each symtab, we keep track of which BFD it came from.  */
  53 #define EXTRA_SYMTAB_INFO       \
  54         unsigned    nonreloc:1;         /* TRUE if non relocatable */
  55
  56 #define INIT_EXTRA_SYMTAB_INFO(symtab)  \
  57         symtab->nonreloc = 0;           \
  58
  59 extern unsigned int text_start, data_start;
  60 extern int inferior_pid;
  61 extern char *corefile;
  62
  63 /* setpgrp() messes up controling terminal. The other version of it
  64    requires libbsd.a. */
  65 #define setpgrp(XX,YY)          setpgid (XX, YY)
  66
  67 /* We are missing register descriptions in the system header files. Sigh! */
  68
  69 struct regs {
  70         int     gregs [32];             /* general purpose registers */
  71         int     pc;                     /* program conter       */
  72         int     ps;                     /* processor status, or machine state */
  73 };
  74
  75 struct fp_status {
  76         double  fpregs [32];            /* floating GP registers */
  77 };
  78
  79
  80 /* To be used by function_frame_info. */
  81
  82 struct aix_framedata {
  83   int   offset;                         /* # of bytes in gpr's and fpr's are saved */
  84   int   saved_gpr;                      /* smallest # of saved gpr */
  85   int   saved_fpr;                      /* smallest # of saved fpr */
  86   int   alloca_reg;                     /* alloca register number (frame ptr) */
  87   char  frameless;                      /* true if frameless functions. */
  88   char  nosavedpc;                      /* true if pc not saved. */
  89 };
  90
  91 void
  92 function_frame_info PARAMS ((CORE_ADDR, struct aix_framedata *));
  93
  94 /* Define the byte order of the machine.  */
  95
  96 #define TARGET_BYTE_ORDER       BIG_ENDIAN
  97
  98 /* Define this if the C compiler puts an underscore at the front
  99    of external names before giving them to the linker.  */
 100
 101 #undef NAMES_HAVE_UNDERSCORE
 102
 103 /* AIX's assembler doesn't grok dollar signs in identifiers.
 104    So we use dots instead.  This item must be coordinated with G++. */
 105 #undef CPLUS_MARKER
 106 #define CPLUS_MARKER '.'
 107
 108 /* Offset from address of function to start of its code.
 109    Zero on most machines.  */
 110
 111 #define FUNCTION_START_OFFSET 0
 112
 113 /* Advance PC across any function entry prologue instructions
 114    to reach some "real" code.  */
 115
 116 #define SKIP_PROLOGUE(pc)       pc = skip_prologue (pc)
 117
 118 /* If PC is in some function-call trampoline code, return the PC
 119    where the function itself actually starts.  If not, return NULL.  */
 120
 121 #define SKIP_TRAMPOLINE_CODE(pc)        skip_trampoline_code (pc)
 122
 123 /* When a child process is just starting, we sneak in and relocate
 124    the symbol table (and other stuff) after the dynamic linker has
 125    figured out where they go. But we want to do this relocation just
 126    once. */
 127
 128 extern int loadinfotextindex;
 129
 130 #define SOLIB_CREATE_INFERIOR_HOOK(PID) \
 131   do {                                  \
 132     if (loadinfotextindex == 0) \
 133         xcoff_relocate_symtab (PID);    \
 134   } while (0)
 135
 136
 137 /* Number of trap signals we need to skip over, once the inferior process
 138    starts running. */
 139
 140 #define START_INFERIOR_TRAPS_EXPECTED   2
 141
 142 /* AIX might return a sigtrap, with a "stop after load" status. It should
 143    be ignored by gdb, shouldn't be mixed up with breakpoint traps. */
 144
 145 /* Another little glitch  in AIX is signal 0. I have no idea why wait(2)
 146    returns with this status word. It looks harmless. */
 147
 148 #define SIGTRAP_STOP_AFTER_LOAD(W)      \
 149  if ( (W) == 0x57c || (W) == 0x7f) {    \
 150    if ((W)==0x57c && breakpoints_inserted) {    \
 151      mark_breakpoints_out ();           \
 152      insert_breakpoints ();             \
 153      insert_step_breakpoint ();         \
 154    }                                    \
 155    resume (0, 0);                       \
 156    continue;                            \
 157  }
 158
 159 /* In xcoff, we cannot process line numbers when we see them. This is
 160    mainly because we don't know the boundaries of the include files. So,
 161    we postpone that, and then enter and sort(?) the whole line table at
 162    once, when we are closing the current symbol table in end_symtab(). */
 163
 164 #define PROCESS_LINENUMBER_HOOK()       aix_process_linenos ()
 165
 166
 167 /* When a target process or core-file has been attached, we sneak in
 168    and figure out where the shared libraries have got to. In case there
 169    is no inferior_process exists (e.g. bringing up a core file), we can't
 170    attemtp to relocate symbol table, since we don't have information about
 171    load segments. */
 172
 173 #define SOLIB_ADD(a, b, c)      \
 174    if (inferior_pid)    xcoff_relocate_symtab (inferior_pid)
 175
 176 /* Immediately after a function call, return the saved pc.
 177    Can't go through the frames for this because on some machines
 178    the new frame is not set up until the new function executes
 179    some instructions.  */
 180
 181 #define SAVED_PC_AFTER_CALL(frame) read_register (LR_REGNUM)
 182
 183 /* Address of end of stack space.  */
 184
 185 #define STACK_END_ADDR 0x2ff80000
 186
 187 /* Stack grows downward.  */
 188
 189 #define INNER_THAN <
 190
 191 #if 0
 192 /* No, we shouldn't use this. push_arguments() should leave stack in a
 193    proper alignment! */
 194 /* Stack has strict alignment. */
 195
 196 #define STACK_ALIGN(ADDR)       (((ADDR)+7)&-8)
 197 #endif
 198
 199 /* This is how argumets pushed onto stack or passed in registers. */
 200
 201 #define PUSH_ARGUMENTS(nargs, args, sp, struct_return, struct_addr) \
 202   sp = push_arguments(nargs, args, sp, struct_return, struct_addr)
 203
 204 /* Sequence of bytes for breakpoint instruction.  */
 205
 206 #define BREAKPOINT {0x7d, 0x82, 0x10, 0x08}
 207
 208 /* Amount PC must be decremented by after a breakpoint.
 209    This is often the number of bytes in BREAKPOINT
 210    but not always.  */
 211
 212 #define DECR_PC_AFTER_BREAK 0
 213
 214 /* Nonzero if instruction at PC is a return instruction.  */
 215 /* Allow any of the return instructions, including a trapv and a return
 216    from interrupt.  */
 217
 218 #define ABOUT_TO_RETURN(pc)  \
 219    ((read_memory_integer (pc, 4) & 0xfe8007ff) == 0x4e800020)
 220
 221 /* Return 1 if P points to an invalid floating point value.  */
 222
 223 #define INVALID_FLOAT(p, len) 0   /* Just a first guess; not checked */
 224
 225 /* Largest integer type */
 226
 227 #define LONGEST long
 228
 229 /* Name of the builtin type for the LONGEST type above. */
 230
 231 #define BUILTIN_TYPE_LONGEST builtin_type_long
 232
 233 /* Say how long (ordinary) registers are.  */
 234
 235 #define REGISTER_TYPE long
 236
 237 /* Number of machine registers */
 238
 239 #define NUM_REGS 71
 240
 241 /* Initializer for an array of names of registers.
 242    There should be NUM_REGS strings in this initializer.  */
 243
 244 #define REGISTER_NAMES  \
 245  {"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",  \
 246   "r8", "r9", "r10","r11","r12","r13","r14","r15", \
 247   "r16","r17","r18","r19","r20","r21","r22","r23", \
 248   "r24","r25","r26","r27","r28","r29","r30","r31", \
 249   "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",  \
 250   "f8", "f9", "f10","f11","f12","f13","f14","f15", \
 251   "f16","f17","f18","f19","f20","f21","f22","f23", \
 252   "f24","f25","f26","f27","f28","f29","f30","f31", \
 253   "pc", "ps", "cnd", "lr", "cnt", "xer", "mq" }
 254
 255 /* Register numbers of various important registers.
 256    Note that some of these values are "real" register numbers,
 257    and correspond to the general registers of the machine,
 258    and some are "phony" register numbers which are too large
 259    to be actual register numbers as far as the user is concerned
 260    but do serve to get the desired values when passed to read_register.  */
 261
 262 #define FP_REGNUM 1             /* Contains address of executing stack frame */
 263 #define SP_REGNUM 1             /* Contains address of top of stack */
 264 #define TOC_REGNUM 2            /* TOC register */
 265 #define FP0_REGNUM 32           /* Floating point register 0 */
 266 #define GP0_REGNUM 0            /* GPR register 0 */
 267 #define FP0_REGNUM 32           /* FPR (Floating point) register 0 */
 268 #define FPLAST_REGNUM 63        /* Last floating point register */
 269
 270 /* Special purpose registers... */
 271 /* P.S. keep these in the same order as in /usr/mstsave.h `mstsave' structure, for
 272    easier processing */
 273
 274 #define PC_REGNUM 64            /* Program counter (instruction address %iar) */
 275 #define PS_REGNUM 65            /* Processor (or machine) status (%msr) */
 276 #define CR_REGNUM 66            /* Condition register */
 277 #define LR_REGNUM 67            /* Link register */
 278 #define CTR_REGNUM 68           /* Count register */
 279 #define XER_REGNUM 69           /* Fixed point exception registers */
 280 #define MQ_REGNUM 70            /* Multiply/quotient register */
 281
 282 #define FIRST_SP_REGNUM 64      /* first special register number */
 283 #define LAST_SP_REGNUM  70      /* last special register number */
 284
 285 /* Total amount of space needed to store our copies of the machine's
 286    register state, the array `registers'.
 287
 288         32 4-byte gpr's
 289         32 8-byte fpr's
 290         7  4-byte special purpose registers,
 291
 292    total 416 bytes. Keep some extra space for now, in case to add more. */
 293
 294 #define REGISTER_BYTES 420
 295
 296
 297 /* Index within `registers' of the first byte of the space for
 298    register N.  */
 299
 300 #define REGISTER_BYTE(N)  \
 301  (                                                              \
 302   ((N) > FPLAST_REGNUM) ? ((((N) - FPLAST_REGNUM -1) * 4) + 384)\
 303   :((N) >= FP0_REGNUM) ? ((((N) - FP0_REGNUM) * 8) + 128)       \
 304   :((N) * 4) )
 305
 306 /* Number of bytes of storage in the actual machine representation
 307    for register N. */
 308 /* Note that the unsigned cast here forces the result of the
 309    subtractiion to very high positive values if N < FP0_REGNUM */
 310
 311 #define REGISTER_RAW_SIZE(N) (((unsigned)(N) - FP0_REGNUM) < 32 ? 8 : 4)
 312
 313 /* Number of bytes of storage in the program's representation
 314    for register N.  On the RS6000, all regs are 4 bytes
 315    except the floating point regs which are 8-byte doubles.  */
 316
 317 #define REGISTER_VIRTUAL_SIZE(N) (((unsigned)(N) - FP0_REGNUM) < 32 ? 8 : 4)
 318
 319 /* Largest value REGISTER_RAW_SIZE can have.  */
 320
 321 #define MAX_REGISTER_RAW_SIZE 8
 322
 323 /* Largest value REGISTER_VIRTUAL_SIZE can have.  */
 324
 325 #define MAX_REGISTER_VIRTUAL_SIZE 8
 326
 327 /* convert a dbx stab register number (from `r' declaration) to a gdb REGNUM */
 328
 329 #define STAB_REG_TO_REGNUM(value)       (value)
 330
 331 /* Nonzero if register N requires conversion
 332    from raw format to virtual format.  */
 333
 334 #define REGISTER_CONVERTIBLE(N) ((N) >= FP0_REGNUM && (N) <= FPLAST_REGNUM)
 335
 336 /* Convert data from raw format for register REGNUM
 337    to virtual format for register REGNUM.  */
 338
 339 #define REGISTER_CONVERT_TO_VIRTUAL(REGNUM,FROM,TO)     \
 340    bcopy ((FROM), (TO), REGISTER_RAW_SIZE (REGNUM))
 341
 342 /* Convert data from virtual format for register REGNUM
 343    to raw format for register REGNUM.  */
 344
 345 #define REGISTER_CONVERT_TO_RAW(REGNUM,FROM,TO) \
 346    bcopy ((FROM), (TO), REGISTER_RAW_SIZE (REGNUM))
 347
 348 /* Return the GDB type object for the "standard" data type
 349    of data in register N.  */
 350
 351 #define REGISTER_VIRTUAL_TYPE(N) \
 352  (((unsigned)(N) - FP0_REGNUM) < 32 ? builtin_type_double : builtin_type_int)
 353
 354 /* Store the address of the place in which to copy the structure the
 355    subroutine will return.  This is called from call_function. */
 356 /* in RS6000, struct return addresses are passed as an extra parameter in r3.
 357    In function return, callee is not responsible of returning this address back.
 358    Since gdb needs to find it, we will store in a designated variable
 359    `rs6000_struct_return_address'. */
 360
 361 extern unsigned int rs6000_struct_return_address;
 362
 363 #define STORE_STRUCT_RETURN(ADDR, SP)   \
 364   { write_register (3, (ADDR));         \
 365     rs6000_struct_return_address = (unsigned int)(ADDR); }
 366
 367 /* Extract from an array REGBUF containing the (raw) register state
 368    a function return value of type TYPE, and copy that, in virtual format,
 369    into VALBUF.  */
 370
 371 /* #define EXTRACT_RETURN_VALUE(TYPE,REGBUF,VALBUF) \
 372   bcopy (REGBUF, VALBUF, TYPE_LENGTH (TYPE)) */
 373
 374 #define EXTRACT_RETURN_VALUE(TYPE,REGBUF,VALBUF) \
 375   extract_return_value(TYPE,REGBUF,VALBUF)
 376
 377 /* Write into appropriate registers a function return value
 378    of type TYPE, given in virtual format.  */
 379
 380 #define STORE_RETURN_VALUE(TYPE,VALBUF) \
 381   {                                                                     \
 382     if (TYPE_CODE (TYPE) == TYPE_CODE_FLT)                              \
 383                                                                         \
 384      /* Floating point values are returned starting from FPR1 and up.   \
 385         Say a double_double_double type could be returned in            \
 386         FPR1/FPR2/FPR3 triple. */                                       \
 387                                                                         \
 388       write_register_bytes (REGISTER_BYTE (FP0_REGNUM+1), (VALBUF),     \
 389                                                 TYPE_LENGTH (TYPE));    \
 390     else                                                                \
 391       /* Everything else is returned in GPR3 and up. */                 \
 392       write_register_bytes (REGISTER_BYTE (GP0_REGNUM+3), (VALBUF),     \
 393                                                 TYPE_LENGTH (TYPE));    \
 394   }
 395
 396
 397 /* Extract from an array REGBUF containing the (raw) register state
 398    the address in which a function should return its structure value,
 399    as a CORE_ADDR (or an expression that can be used as one).  */
 400
 401 #define EXTRACT_STRUCT_VALUE_ADDRESS(REGBUF)    rs6000_struct_return_address
 402 \f
 403 /* Describe the pointer in each stack frame to the previous stack frame
 404    (its caller).  */
 405
 406 /* FRAME_CHAIN takes a frame's nominal address
 407    and produces the frame's chain-pointer. */
 408
 409 /* In the case of the RS6000, the frame's nominal address
 410    is the address of a 4-byte word containing the calling frame's address.  */
 411
 412 #define FRAME_CHAIN(thisframe)  \
 413   (!inside_entry_file ((thisframe)->pc) ?       \
 414    read_memory_integer ((thisframe)->frame, 4) :\
 415    0)
 416
 417 /* Define other aspects of the stack frame.  */
 418
 419 /* A macro that tells us whether the function invocation represented
 420    by FI does not have a frame on the stack associated with it.  If it
 421    does not, FRAMELESS is set to 1, else 0.  */
 422
 423 #define FRAMELESS_FUNCTION_INVOCATION(FI, FRAMELESS) \
 424         FRAMELESS = frameless_function_invocation (FI, 0)
 425
 426 /* Functions calling alloca() change the value of the stack pointer. We
 427    need to use initial stack pointer (which is saved in r31 by gcc) in
 428    such cases. If a compiler emits traceback table, then we should use the
 429    alloca register specified in traceback table. FIXME. */
 430 /* Also, it is a good idea to cache information about frame's saved registers
 431    in the frame structure to speed things up. See tm-m88k.h. FIXME. */
 432
 433 #define EXTRA_FRAME_INFO        \
 434         CORE_ADDR initial_sp;                   /* initial stack pointer. */ \
 435         struct frame_saved_regs *cache_fsr;     /* saved registers        */
 436
 437 /* Frameless function invocation in IBM RS/6000 is sometimes
 438    half-done. It perfectly sets up a new frame, e.g. a new frame (in
 439    fact stack) pointer, etc, but it doesn't save the %pc.  We call
 440    frameless_function_invocation to tell us how to get the %pc.  */
 441
 442 #define INIT_EXTRA_FRAME_INFO(fromleaf, fi)     \
 443         fi->initial_sp = 0;             \
 444         fi->cache_fsr = 0;
 445
 446 #define FRAME_SAVED_PC(FRAME)                                   \
 447         (frameless_function_invocation (FRAME, 1)               \
 448          ? SAVED_PC_AFTER_CALL (FRAME)                          \
 449          : read_memory_integer (read_memory_integer ((FRAME)->frame, 4)+8, 4))
 450
 451 #define FRAME_ARGS_ADDRESS(FI)  \
 452   (((struct frame_info*)(FI))->initial_sp ?             \
 453         ((struct frame_info*)(FI))->initial_sp :        \
 454         frame_initial_stack_address (FI))
 455
 456 #define FRAME_LOCALS_ADDRESS(FI)        FRAME_ARGS_ADDRESS(FI)
 457
 458
 459 /* Set VAL to the number of args passed to frame described by FI.
 460    Can set VAL to -1, meaning no way to tell.  */
 461
 462 /* We can't tell how many args there are
 463    now that the C compiler delays popping them.  */
 464
 465 #define FRAME_NUM_ARGS(val,fi) (val = -1)
 466
 467 /* Return number of bytes at start of arglist that are not really args.  */
 468
 469 #define FRAME_ARGS_SKIP 8       /* Not sure on this. FIXMEmgo */
 470
 471 /* Put here the code to store, into a struct frame_saved_regs,
 472    the addresses of the saved registers of frame described by FRAME_INFO.
 473    This includes special registers such as pc and fp saved in special
 474    ways in the stack frame.  sp is even more special:
 475    the address we return for it IS the sp for the next frame.  */
 476 /* In the following implementation for RS6000, we did *not* save sp. I am
 477    not sure if it will be needed. The following macro takes care of gpr's
 478    and fpr's only. */
 479
 480 #define FRAME_FIND_SAVED_REGS(FRAME_INFO, FRAME_SAVED_REGS)             \
 481 {                                                                       \
 482   int ii;                                                               \
 483   CORE_ADDR frame_addr, func_start;                                     \
 484   struct aix_framedata fdata;                                           \
 485                                                                         \
 486   /* find the start of the function and collect info about its frame. */\
 487                                                                         \
 488   func_start = get_pc_function_start ((FRAME_INFO)->pc) + FUNCTION_START_OFFSET; \
 489   function_frame_info (func_start, &fdata);                             \
 490   bzero (&(FRAME_SAVED_REGS), sizeof (FRAME_SAVED_REGS));               \
 491                                                                         \
 492   /* if there were any saved registers, figure out parent's stack pointer. */ \
 493   frame_addr = 0;                                                       \
 494   /* the following is true only if the frame doesn't have a call to alloca(), \
 495       FIXME. */                                                         \
 496   if (fdata.saved_fpr >= 0 || fdata.saved_gpr >= 0) {                   \
 497     if ((FRAME_INFO)->prev && (FRAME_INFO)->prev->frame)                \
 498       frame_addr = (FRAME_INFO)->prev->frame;                           \
 499     else                                                                \
 500       frame_addr = read_memory_integer ((FRAME_INFO)->frame, 4);        \
 501   }                                                                     \
 502                                                                         \
 503   /* if != -1, fdata.saved_fpr is the smallest number of saved_fpr. All fpr's \
 504      from saved_fpr to fp31 are saved right underneath caller stack pointer, \
 505      starting from fp31 first. */                                       \
 506                                                                         \
 507   if (fdata.saved_fpr >= 0) {                                           \
 508     for (ii=31; ii >= fdata.saved_fpr; --ii)                            \
 509       (FRAME_SAVED_REGS).regs [FP0_REGNUM + ii] = frame_addr - ((32 - ii) * 8); \
 510     frame_addr -= (32 - fdata.saved_fpr) * 8;                           \
 511   }                                                                     \
 512                                                                         \
 513   /* if != -1, fdata.saved_gpr is the smallest number of saved_gpr. All gpr's \
 514      from saved_gpr to gpr31 are saved right under saved fprs, starting \
 515      from r31 first. */                                                 \
 516                                                                         \
 517   if (fdata.saved_gpr >= 0)                                             \
 518     for (ii=31; ii >= fdata.saved_gpr; --ii)                            \
 519       (FRAME_SAVED_REGS).regs [ii] = frame_addr - ((32 - ii) * 4);      \
 520 }
 521
 522 \f
 523 /* Things needed for making the inferior call functions.  */
 524
 525 /* Push an empty stack frame, to record the current PC, etc.  */
 526 /* Change these names into rs6k_{push, pop}_frame(). FIXMEmgo. */
 527
 528 #define PUSH_DUMMY_FRAME        push_dummy_frame ()
 529
 530 /* Discard from the stack the innermost frame,
 531    restoring all saved registers.  */
 532
 533 #define POP_FRAME       pop_frame ()
 534
 535 /* This sequence of words is the instructions:
 536
 537         mflr    r0              // 0x7c0802a6
 538                                 // save fpr's
 539         stfd    r?, num(r1)     // 0xd8010000 there should be 32 of this??
 540                                 // save gpr's
 541         stm     r0, num(r1)     // 0xbc010000
 542         stu     r1, num(r1)     // 0x94210000
 543
 544         // the function we want to branch might be in a different load
 545         // segment. reset the toc register. Note that the actual toc address
 546         // will be fix by fix_call_dummy () along with function address.
 547
 548         st      r2, 0x14(r1)    // 0x90410014 save toc register
 549         liu     r2, 0x1234      // 0x3c401234 reset a new toc value 0x12345678
 550         oril    r2, r2,0x5678   // 0x60425678
 551
 552                                 // load absolute address 0x12345678 to r0
 553         liu     r0, 0x1234      // 0x3c001234
 554         oril    r0, r0,0x5678   // 0x60005678
 555         mtctr   r0              // 0x7c0903a6 ctr <- r0
 556         bctrl                   // 0x4e800421 jump subroutine 0x12345678 (%ctr)
 557         cror    0xf, 0xf, 0xf   // 0x4def7b82
 558         brpt                    // 0x7d821008, breakpoint
 559         cror    0xf, 0xf, 0xf   // 0x4def7b82 (for 8 byte alignment)
 560
 561
 562   We actually start executing by saving the toc register first, since the pushing
 563   of the registers is done by PUSH_DUMMY_FRAME.  If this were real code,
 564   the arguments for the function called by the `bctrl' would be pushed
 565   between the `stu' and the `bctrl', and we could allow it to execute through.
 566   But the arguments have to be pushed by GDB after the PUSH_DUMMY_FRAME is done,
 567   and we cannot allow to push the registers again.
 568 */
 569
 570 #define CALL_DUMMY {0x7c0802a6, 0xd8010000, 0xbc010000, 0x94210000, \
 571                     0x90410014, 0x3c401234, 0x60425678,             \
 572                     0x3c001234, 0x60005678, 0x7c0903a6, 0x4e800421, \
 573                     0x4def7b82, 0x7d821008, 0x4def7b82 }
 574
 575
 576 /* keep this as multiple of 8 (%sp requires 8 byte alignment) */
 577 #define CALL_DUMMY_LENGTH 56
 578
 579 #define CALL_DUMMY_START_OFFSET 16
 580
 581 /* Insert the specified number of args and function address
 582    into a call sequence of the above form stored at DUMMYNAME.  */
 583
 584 #define FIX_CALL_DUMMY(dummyname, pc, fun, nargs, args, type, using_gcc) \
 585         fix_call_dummy(dummyname, pc, fun, nargs, type)
 586
 587
 588 /* Signal handler for SIGWINCH `window size changed'. */
 589
 590 #define SIGWINCH_HANDLER  aix_resizewindow
 591 extern  void    aix_resizewindow ();
 592
 593 /* `lines_per_page' and `chars_per_line' are local to utils.c. Rectify this. */
 594
 595 #define SIGWINCH_HANDLER_BODY   \
 596                                                                         \
 597 /* Respond to SIGWINCH `window size changed' signal, and reset GDB's    \
 598    window settings approproatelt. */                                    \
 599                                                                         \
 600 void                                            \
 601 aix_resizewindow ()                             \
 602 {                                               \
 603   int fd = fileno (stdout);                     \
 604   if (isatty (fd)) {                            \
 605     int val;                                    \
 606                                                 \
 607     val = atoi (termdef (fd, 'l'));             \
 608     if (val > 0)                                \
 609       lines_per_page = val;                     \
 610     val = atoi (termdef (fd, 'c'));             \
 611     if (val > 0)                                \
 612       chars_per_line = val;                     \
 613   }                                             \
 614 }
 615
 616
 617 /* Flag for machine-specific stuff in shared files.  FIXME */
 618 #define IBM6000_TARGET
 619
 620 /* RS6000/AIX does not support PT_STEP.  Has to be simulated.  */
 621
 622 #define NO_SINGLE_STEP