src/bytecode.c

   1 /* Execution of byte code produced by bytecomp.el.
   2    Copyright (C) 1985, 1986, 1987, 1988, 1993, 2000, 2001, 2002
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs 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, or (at your option)
  10 any later version.
  11
  12 GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to
  19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.
  21
  22 hacked on by jwz@lucid.com 17-jun-91
  23   o  added a compile-time switch to turn on simple sanity checking;
  24   o  put back the obsolete byte-codes for error-detection;
  25   o  added a new instruction, unbind_all, which I will use for
  26      tail-recursion elimination;
  27   o  made temp_output_buffer_show be called with the right number
  28      of args;
  29   o  made the new bytecodes be called with args in the right order;
  30   o  added metering support.
  31
  32 by Hallvard:
  33   o  added relative jump instructions;
  34   o  all conditionals now only do QUIT if they jump.
  35  */
  36
  37 #include <config.h>
  38 #include "lisp.h"
  39 #include "buffer.h"
  40 #include "charset.h"
  41 #include "syntax.h"
  42
  43 #ifdef CHECK_FRAME_FONT
  44 #include "frame.h"
  45 #include "xterm.h"
  46 #endif
  47
  48 /*
  49  * define BYTE_CODE_SAFE to enable some minor sanity checking (useful for
  50  * debugging the byte compiler...)
  51  *
  52  * define BYTE_CODE_METER to enable generation of a byte-op usage histogram.
  53  */
  54 /* #define BYTE_CODE_SAFE */
  55 /* #define BYTE_CODE_METER */
  56
  57 \f
  58 #ifdef BYTE_CODE_METER
  59
  60 Lisp_Object Vbyte_code_meter, Qbyte_code_meter;
  61 int byte_metering_on;
  62
  63 #define METER_2(code1, code2) \
  64   XFASTINT (XVECTOR (XVECTOR (Vbyte_code_meter)->contents[(code1)]) \
  65             ->contents[(code2)])
  66
  67 #define METER_1(code) METER_2 (0, (code))
  68
  69 #define METER_CODE(last_code, this_code)                                \
  70 {                                                                       \
  71   if (byte_metering_on)                                                 \
  72     {                                                                   \
  73       if (METER_1 (this_code) < MOST_POSITIVE_FIXNUM)                   \
  74         METER_1 (this_code)++;                                          \
  75       if (last_code                                                     \
  76           && METER_2 (last_code, this_code) < MOST_POSITIVE_FIXNUM)     \
  77         METER_2 (last_code, this_code)++;                               \
  78     }                                                                   \
  79 }
  80
  81 #else /* no BYTE_CODE_METER */
  82
  83 #define METER_CODE(last_code, this_code)
  84
  85 #endif /* no BYTE_CODE_METER */
  86 \f
  87
  88 Lisp_Object Qbytecode;
  89
  90 /*  Byte codes: */
  91
  92 #define Bvarref 010
  93 #define Bvarset 020
  94 #define Bvarbind 030
  95 #define Bcall 040
  96 #define Bunbind 050
  97
  98 #define Bnth 070
  99 #define Bsymbolp 071
 100 #define Bconsp 072
 101 #define Bstringp 073
 102 #define Blistp 074
 103 #define Beq 075
 104 #define Bmemq 076
 105 #define Bnot 077
 106 #define Bcar 0100
 107 #define Bcdr 0101
 108 #define Bcons 0102
 109 #define Blist1 0103
 110 #define Blist2 0104
 111 #define Blist3 0105
 112 #define Blist4 0106
 113 #define Blength 0107
 114 #define Baref 0110
 115 #define Baset 0111
 116 #define Bsymbol_value 0112
 117 #define Bsymbol_function 0113
 118 #define Bset 0114
 119 #define Bfset 0115
 120 #define Bget 0116
 121 #define Bsubstring 0117
 122 #define Bconcat2 0120
 123 #define Bconcat3 0121
 124 #define Bconcat4 0122
 125 #define Bsub1 0123
 126 #define Badd1 0124
 127 #define Beqlsign 0125
 128 #define Bgtr 0126
 129 #define Blss 0127
 130 #define Bleq 0130
 131 #define Bgeq 0131
 132 #define Bdiff 0132
 133 #define Bnegate 0133
 134 #define Bplus 0134
 135 #define Bmax 0135
 136 #define Bmin 0136
 137 #define Bmult 0137
 138
 139 #define Bpoint 0140
 140 /* Was Bmark in v17.  */
 141 #define Bsave_current_buffer 0141
 142 #define Bgoto_char 0142
 143 #define Binsert 0143
 144 #define Bpoint_max 0144
 145 #define Bpoint_min 0145
 146 #define Bchar_after 0146
 147 #define Bfollowing_char 0147
 148 #define Bpreceding_char 0150
 149 #define Bcurrent_column 0151
 150 #define Bindent_to 0152
 151 #define Bscan_buffer 0153 /* No longer generated as of v18 */
 152 #define Beolp 0154
 153 #define Beobp 0155
 154 #define Bbolp 0156
 155 #define Bbobp 0157
 156 #define Bcurrent_buffer 0160
 157 #define Bset_buffer 0161
 158 #define Bsave_current_buffer_1 0162 /* Replacing Bsave_current_buffer.  */
 159 #define Bread_char 0162 /* No longer generated as of v19 */
 160 #define Bset_mark 0163 /* this loser is no longer generated as of v18 */
 161 #define Binteractive_p 0164 /* Needed since interactive-p takes unevalled args */
 162
 163 #define Bforward_char 0165
 164 #define Bforward_word 0166
 165 #define Bskip_chars_forward 0167
 166 #define Bskip_chars_backward 0170
 167 #define Bforward_line 0171
 168 #define Bchar_syntax 0172
 169 #define Bbuffer_substring 0173
 170 #define Bdelete_region 0174
 171 #define Bnarrow_to_region 0175
 172 #define Bwiden 0176
 173 #define Bend_of_line 0177
 174
 175 #define Bconstant2 0201
 176 #define Bgoto 0202
 177 #define Bgotoifnil 0203
 178 #define Bgotoifnonnil 0204
 179 #define Bgotoifnilelsepop 0205
 180 #define Bgotoifnonnilelsepop 0206
 181 #define Breturn 0207
 182 #define Bdiscard 0210
 183 #define Bdup 0211
 184
 185 #define Bsave_excursion 0212
 186 #define Bsave_window_excursion 0213
 187 #define Bsave_restriction 0214
 188 #define Bcatch 0215
 189
 190 #define Bunwind_protect 0216
 191 #define Bcondition_case 0217
 192 #define Btemp_output_buffer_setup 0220
 193 #define Btemp_output_buffer_show 0221
 194
 195 #define Bunbind_all 0222
 196
 197 #define Bset_marker 0223
 198 #define Bmatch_beginning 0224
 199 #define Bmatch_end 0225
 200 #define Bupcase 0226
 201 #define Bdowncase 0227
 202
 203 #define Bstringeqlsign 0230
 204 #define Bstringlss 0231
 205 #define Bequal 0232
 206 #define Bnthcdr 0233
 207 #define Belt 0234
 208 #define Bmember 0235
 209 #define Bassq 0236
 210 #define Bnreverse 0237
 211 #define Bsetcar 0240
 212 #define Bsetcdr 0241
 213 #define Bcar_safe 0242
 214 #define Bcdr_safe 0243
 215 #define Bnconc 0244
 216 #define Bquo 0245
 217 #define Brem 0246
 218 #define Bnumberp 0247
 219 #define Bintegerp 0250
 220
 221 #define BRgoto 0252
 222 #define BRgotoifnil 0253
 223 #define BRgotoifnonnil 0254
 224 #define BRgotoifnilelsepop 0255
 225 #define BRgotoifnonnilelsepop 0256
 226
 227 #define BlistN 0257
 228 #define BconcatN 0260
 229 #define BinsertN 0261
 230
 231 #define Bconstant 0300
 232 #define CONSTANTLIM 0100
 233
 234 \f
 235 /* Structure describing a value stack used during byte-code execution
 236    in Fbyte_code.  */
 237
 238 struct byte_stack
 239 {
 240   /* Program counter.  This points into the byte_string below
 241      and is relocated when that string is relocated.  */
 242   const unsigned char *pc;
 243
 244   /* Top and bottom of stack.  The bottom points to an area of memory
 245      allocated with alloca in Fbyte_code.  */
 246   Lisp_Object *top, *bottom;
 247
 248   /* The string containing the byte-code, and its current address.
 249      Storing this here protects it from GC because mark_byte_stack
 250      marks it.  */
 251   Lisp_Object byte_string;
 252   const unsigned char *byte_string_start;
 253
 254   /* The vector of constants used during byte-code execution.  Storing
 255      this here protects it from GC because mark_byte_stack marks it.  */
 256   Lisp_Object constants;
 257
 258   /* Next entry in byte_stack_list.  */
 259   struct byte_stack *next;
 260 };
 261
 262 /* A list of currently active byte-code execution value stacks.
 263    Fbyte_code adds an entry to the head of this list before it starts
 264    processing byte-code, and it removed the entry again when it is
 265    done.  Signalling an error truncates the list analoguous to
 266    gcprolist.  */
 267
 268 struct byte_stack *byte_stack_list;
 269
 270 \f
 271 /* Mark objects on byte_stack_list.  Called during GC.  */
 272
 273 void
 274 mark_byte_stack ()
 275 {
 276   struct byte_stack *stack;
 277   Lisp_Object *obj;
 278
 279   for (stack = byte_stack_list; stack; stack = stack->next)
 280     {
 281       /* If STACK->top is null here, this means there's an opcode in
 282          Fbyte_code that wasn't expected to GC, but did.  To find out
 283          which opcode this is, record the value of `stack', and walk
 284          up the stack in a debugger, stopping in frames of Fbyte_code.
 285          The culprit is found in the frame of Fbyte_code where the
 286          address of its local variable `stack' is equal to the
 287          recorded value of `stack' here.  */
 288       if (!stack->top)
 289         abort ();
 290
 291       for (obj = stack->bottom; obj <= stack->top; ++obj)
 292         if (!XMARKBIT (*obj))
 293           {
 294             mark_object (obj);
 295             XMARK (*obj);
 296           }
 297
 298       if (!XMARKBIT (stack->byte_string))
 299         {
 300           mark_object (&stack->byte_string);
 301           XMARK (stack->byte_string);
 302         }
 303
 304       if (!XMARKBIT (stack->constants))
 305         {
 306           mark_object (&stack->constants);
 307           XMARK (stack->constants);
 308         }
 309     }
 310 }
 311
 312
 313 /* Unmark objects in the stacks on byte_stack_list.  Relocate program
 314    counters.  Called when GC has completed.  */
 315
 316 void
 317 unmark_byte_stack ()
 318 {
 319   struct byte_stack *stack;
 320   Lisp_Object *obj;
 321
 322   for (stack = byte_stack_list; stack; stack = stack->next)
 323     {
 324       for (obj = stack->bottom; obj <= stack->top; ++obj)
 325         XUNMARK (*obj);
 326
 327       XUNMARK (stack->byte_string);
 328       XUNMARK (stack->constants);
 329
 330       if (stack->byte_string_start != SDATA (stack->byte_string))
 331         {
 332           int offset = stack->pc - stack->byte_string_start;
 333           stack->byte_string_start = SDATA (stack->byte_string);
 334           stack->pc = stack->byte_string_start + offset;
 335         }
 336     }
 337 }
 338
 339 \f
 340 /* Fetch the next byte from the bytecode stream */
 341
 342 #define FETCH *stack.pc++
 343
 344 /* Fetch two bytes from the bytecode stream and make a 16-bit number
 345    out of them */
 346
 347 #define FETCH2 (op = FETCH, op + (FETCH << 8))
 348
 349 /* Push x onto the execution stack.  This used to be #define PUSH(x)
 350    (*++stackp = (x)) This oddity is necessary because Alliant can't be
 351    bothered to compile the preincrement operator properly, as of 4/91.
 352    -JimB */
 353
 354 #define PUSH(x) (top++, *top = (x))
 355
 356 /* Pop a value off the execution stack.  */
 357
 358 #define POP (*top--)
 359
 360 /* Discard n values from the execution stack.  */
 361
 362 #define DISCARD(n) (top -= (n))
 363
 364 /* Get the value which is at the top of the execution stack, but don't
 365    pop it. */
 366
 367 #define TOP (*top)
 368
 369 /* Actions that must be performed before and after calling a function
 370    that might GC.  */
 371
 372 #define BEFORE_POTENTIAL_GC()   stack.top = top
 373 #define AFTER_POTENTIAL_GC()    stack.top = NULL
 374
 375 /* Garbage collect if we have consed enough since the last time.
 376    We do this at every branch, to avoid loops that never GC.  */
 377
 378 #define MAYBE_GC()                              \
 379   if (consing_since_gc > gc_cons_threshold)     \
 380     {                                           \
 381       BEFORE_POTENTIAL_GC ();                   \
 382       Fgarbage_collect ();                      \
 383       AFTER_POTENTIAL_GC ();                    \
 384     }                                           \
 385   else
 386
 387 /* Check for jumping out of range.  */
 388
 389 #ifdef BYTE_CODE_SAFE
 390
 391 #define CHECK_RANGE(ARG) \
 392   if (ARG >= bytestr_length) abort ()
 393
 394 #else /* not BYTE_CODE_SAFE */
 395
 396 #define CHECK_RANGE(ARG)
 397
 398 #endif /* not BYTE_CODE_SAFE */
 399
 400 /* A version of the QUIT macro which makes sure that the stack top is
 401    set before signaling `quit'.  */
 402
 403 #define BYTE_CODE_QUIT                                  \
 404   do {                                                  \
 405     if (!NILP (Vquit_flag) && NILP (Vinhibit_quit))     \
 406       {                                                 \
 407         Vquit_flag = Qnil;                              \
 408         BEFORE_POTENTIAL_GC ();                         \
 409         Fsignal (Qquit, Qnil);                          \
 410       }                                                 \
 411   } while (0)
 412
 413
 414 DEFUN ("byte-code", Fbyte_code, Sbyte_code, 3, 3, 0,
 415        doc: /* Function used internally in byte-compiled code.
 416 The first argument, BYTESTR, is a string of byte code;
 417 the second, VECTOR, a vector of constants;
 418 the third, MAXDEPTH, the maximum stack depth used in this function.
 419 If the third argument is incorrect, Emacs may crash.  */)
 420      (bytestr, vector, maxdepth)
 421      Lisp_Object bytestr, vector, maxdepth;
 422 {
 423   int count = SPECPDL_INDEX ();
 424 #ifdef BYTE_CODE_METER
 425   int this_op = 0;
 426   int prev_op;
 427 #endif
 428   int op;
 429   /* Lisp_Object v1, v2; */
 430   Lisp_Object *vectorp;
 431 #ifdef BYTE_CODE_SAFE
 432   int const_length = XVECTOR (vector)->size;
 433   Lisp_Object *stacke;
 434 #endif
 435   int bytestr_length;
 436   struct byte_stack stack;
 437   Lisp_Object *top;
 438   Lisp_Object result;
 439
 440 #ifdef CHECK_FRAME_FONT
 441  {
 442    struct frame *f = SELECTED_FRAME ();
 443    if (FRAME_X_P (f)
 444        && FRAME_FONT (f)->direction != 0
 445        && FRAME_FONT (f)->direction != 1)
 446      abort ();
 447  }
 448 #endif
 449
 450   CHECK_STRING (bytestr);
 451   if (!VECTORP (vector))
 452     vector = wrong_type_argument (Qvectorp, vector);
 453   CHECK_NUMBER (maxdepth);
 454
 455   if (STRING_MULTIBYTE (bytestr))
 456     /* BYTESTR must have been produced by Emacs 20.2 or the earlier
 457        because they produced a raw 8-bit string for byte-code and now
 458        such a byte-code string is loaded as multibyte while raw 8-bit
 459        characters converted to multibyte form.  Thus, now we must
 460        convert them back to the originally intended unibyte form.  */
 461     bytestr = Fstring_as_unibyte (bytestr);
 462
 463   bytestr_length = SBYTES (bytestr);
 464   vectorp = XVECTOR (vector)->contents;
 465
 466   stack.byte_string = bytestr;
 467   stack.pc = stack.byte_string_start = SDATA (bytestr);
 468   stack.constants = vector;
 469   stack.bottom = (Lisp_Object *) alloca (XFASTINT (maxdepth)
 470                                          * sizeof (Lisp_Object));
 471   top = stack.bottom - 1;
 472   stack.top = NULL;
 473   stack.next = byte_stack_list;
 474   byte_stack_list = &stack;
 475
 476 #ifdef BYTE_CODE_SAFE
 477   stacke = stack.bottom - 1 + XFASTINT (maxdepth);
 478 #endif
 479
 480   while (1)
 481     {
 482 #ifdef BYTE_CODE_SAFE
 483       if (top > stacke)
 484         abort ();
 485       else if (top < stack.bottom - 1)
 486         abort ();
 487 #endif
 488
 489 #ifdef BYTE_CODE_METER
 490       prev_op = this_op;
 491       this_op = op = FETCH;
 492       METER_CODE (prev_op, op);
 493 #else
 494       op = FETCH;
 495 #endif
 496
 497       switch (op)
 498         {
 499         case Bvarref + 7:
 500           op = FETCH2;
 501           goto varref;
 502
 503         case Bvarref:
 504         case Bvarref + 1:
 505         case Bvarref + 2:
 506         case Bvarref + 3:
 507         case Bvarref + 4:
 508         case Bvarref + 5:
 509           op = op - Bvarref;
 510           goto varref;
 511
 512         /* This seems to be the most frequently executed byte-code
 513            among the Bvarref's, so avoid a goto here.  */
 514         case Bvarref+6:
 515           op = FETCH;
 516         varref:
 517           {
 518             Lisp_Object v1, v2;
 519
 520             v1 = vectorp[op];
 521             if (SYMBOLP (v1))
 522               {
 523                 v2 = SYMBOL_VALUE (v1);
 524                 if (MISCP (v2) || EQ (v2, Qunbound))
 525                   {
 526                     BEFORE_POTENTIAL_GC ();
 527                     v2 = Fsymbol_value (v1);
 528                     AFTER_POTENTIAL_GC ();
 529                   }
 530               }
 531             else
 532               {
 533                 BEFORE_POTENTIAL_GC ();
 534                 v2 = Fsymbol_value (v1);
 535                 AFTER_POTENTIAL_GC ();
 536               }
 537             PUSH (v2);
 538             break;
 539           }
 540
 541         case Bgotoifnil:
 542           MAYBE_GC ();
 543           op = FETCH2;
 544           if (NILP (POP))
 545             {
 546               BYTE_CODE_QUIT;
 547               CHECK_RANGE (op);
 548               stack.pc = stack.byte_string_start + op;
 549             }
 550           break;
 551
 552         case Bcar:
 553           {
 554             Lisp_Object v1;
 555             v1 = TOP;
 556             if (CONSP (v1))
 557               TOP = XCAR (v1);
 558             else if (NILP (v1))
 559               TOP = Qnil;
 560             else
 561               {
 562                 BEFORE_POTENTIAL_GC ();
 563                 Fcar (wrong_type_argument (Qlistp, v1));
 564                 AFTER_POTENTIAL_GC ();
 565               }
 566             break;
 567           }
 568
 569         case Beq:
 570           {
 571             Lisp_Object v1;
 572             v1 = POP;
 573             TOP = EQ (v1, TOP) ? Qt : Qnil;
 574             break;
 575           }
 576
 577         case Bmemq:
 578           {
 579             Lisp_Object v1;
 580             BEFORE_POTENTIAL_GC ();
 581             v1 = POP;
 582             TOP = Fmemq (TOP, v1);
 583             AFTER_POTENTIAL_GC ();
 584             break;
 585           }
 586
 587         case Bcdr:
 588           {
 589             Lisp_Object v1;
 590             v1 = TOP;
 591             if (CONSP (v1))
 592               TOP = XCDR (v1);
 593             else if (NILP (v1))
 594               TOP = Qnil;
 595             else
 596               {
 597                 BEFORE_POTENTIAL_GC ();
 598                 Fcdr (wrong_type_argument (Qlistp, v1));
 599                 AFTER_POTENTIAL_GC ();
 600               }
 601             break;
 602           }
 603
 604         case Bvarset:
 605         case Bvarset+1:
 606         case Bvarset+2:
 607         case Bvarset+3:
 608         case Bvarset+4:
 609         case Bvarset+5:
 610           op -= Bvarset;
 611           goto varset;
 612
 613         case Bvarset+7:
 614           op = FETCH2;
 615           goto varset;
 616
 617         case Bvarset+6:
 618           op = FETCH;
 619         varset:
 620           {
 621             Lisp_Object sym, val;
 622
 623             sym = vectorp[op];
 624             val = TOP;
 625
 626             /* Inline the most common case.  */
 627             if (SYMBOLP (sym)
 628                 && !EQ (val, Qunbound)
 629                 && !XSYMBOL (sym)->indirect_variable
 630                 && !XSYMBOL (sym)->constant
 631                 && !MISCP (XSYMBOL (sym)->value))
 632               XSYMBOL (sym)->value = val;
 633             else
 634               {
 635                 BEFORE_POTENTIAL_GC ();
 636                 set_internal (sym, val, current_buffer, 0);
 637                 AFTER_POTENTIAL_GC ();
 638               }
 639           }
 640           POP;
 641           break;
 642
 643         case Bdup:
 644           {
 645             Lisp_Object v1;
 646             v1 = TOP;
 647             PUSH (v1);
 648             break;
 649           }
 650
 651         /* ------------------ */
 652
 653         case Bvarbind+6:
 654           op = FETCH;
 655           goto varbind;
 656
 657         case Bvarbind+7:
 658           op = FETCH2;
 659           goto varbind;
 660
 661         case Bvarbind:
 662         case Bvarbind+1:
 663         case Bvarbind+2:
 664         case Bvarbind+3:
 665         case Bvarbind+4:
 666         case Bvarbind+5:
 667           op -= Bvarbind;
 668         varbind:
 669           /* Specbind can signal and thus GC.  */
 670           BEFORE_POTENTIAL_GC ();
 671           specbind (vectorp[op], POP);
 672           AFTER_POTENTIAL_GC ();
 673           break;
 674
 675         case Bcall+6:
 676           op = FETCH;
 677           goto docall;
 678
 679         case Bcall+7:
 680           op = FETCH2;
 681           goto docall;
 682
 683         case Bcall:
 684         case Bcall+1:
 685         case Bcall+2:
 686         case Bcall+3:
 687         case Bcall+4:
 688         case Bcall+5:
 689           op -= Bcall;
 690         docall:
 691           {
 692             BEFORE_POTENTIAL_GC ();
 693             DISCARD (op);
 694 #ifdef BYTE_CODE_METER
 695             if (byte_metering_on && SYMBOLP (TOP))
 696               {
 697                 Lisp_Object v1, v2;
 698
 699                 v1 = TOP;
 700                 v2 = Fget (v1, Qbyte_code_meter);
 701                 if (INTEGERP (v2)
 702                     && XINT (v2) < MOST_POSITIVE_FIXNUM)
 703                   {
 704                     XSETINT (v2, XINT (v2) + 1);
 705                     Fput (v1, Qbyte_code_meter, v2);
 706                   }
 707               }
 708 #endif
 709             TOP = Ffuncall (op + 1, &TOP);
 710             AFTER_POTENTIAL_GC ();
 711             break;
 712           }
 713
 714         case Bunbind+6:
 715           op = FETCH;
 716           goto dounbind;
 717
 718         case Bunbind+7:
 719           op = FETCH2;
 720           goto dounbind;
 721
 722         case Bunbind:
 723         case Bunbind+1:
 724         case Bunbind+2:
 725         case Bunbind+3:
 726         case Bunbind+4:
 727         case Bunbind+5:
 728           op -= Bunbind;
 729         dounbind:
 730           BEFORE_POTENTIAL_GC ();
 731           unbind_to (SPECPDL_INDEX () - op, Qnil);
 732           AFTER_POTENTIAL_GC ();
 733           break;
 734
 735         case Bunbind_all:
 736           /* To unbind back to the beginning of this frame.  Not used yet,
 737              but will be needed for tail-recursion elimination.  */
 738           BEFORE_POTENTIAL_GC ();
 739           unbind_to (count, Qnil);
 740           AFTER_POTENTIAL_GC ();
 741           break;
 742
 743         case Bgoto:
 744           MAYBE_GC ();
 745           BYTE_CODE_QUIT;
 746           op = FETCH2;    /* pc = FETCH2 loses since FETCH2 contains pc++ */
 747           CHECK_RANGE (op);
 748           stack.pc = stack.byte_string_start + op;
 749           break;
 750
 751         case Bgotoifnonnil:
 752           MAYBE_GC ();
 753           op = FETCH2;
 754           if (!NILP (POP))
 755             {
 756               BYTE_CODE_QUIT;
 757               CHECK_RANGE (op);
 758               stack.pc = stack.byte_string_start + op;
 759             }
 760           break;
 761
 762         case Bgotoifnilelsepop:
 763           MAYBE_GC ();
 764           op = FETCH2;
 765           if (NILP (TOP))
 766             {
 767               BYTE_CODE_QUIT;
 768               CHECK_RANGE (op);
 769               stack.pc = stack.byte_string_start + op;
 770             }
 771           else DISCARD (1);
 772           break;
 773
 774         case Bgotoifnonnilelsepop:
 775           MAYBE_GC ();
 776           op = FETCH2;
 777           if (!NILP (TOP))
 778             {
 779               BYTE_CODE_QUIT;
 780               CHECK_RANGE (op);
 781               stack.pc = stack.byte_string_start + op;
 782             }
 783           else DISCARD (1);
 784           break;
 785
 786         case BRgoto:
 787           MAYBE_GC ();
 788           BYTE_CODE_QUIT;
 789           stack.pc += (int) *stack.pc - 127;
 790           break;
 791
 792         case BRgotoifnil:
 793           MAYBE_GC ();
 794           if (NILP (POP))
 795             {
 796               BYTE_CODE_QUIT;
 797               stack.pc += (int) *stack.pc - 128;
 798             }
 799           stack.pc++;
 800           break;
 801
 802         case BRgotoifnonnil:
 803           MAYBE_GC ();
 804           if (!NILP (POP))
 805             {
 806               BYTE_CODE_QUIT;
 807               stack.pc += (int) *stack.pc - 128;
 808             }
 809           stack.pc++;
 810           break;
 811
 812         case BRgotoifnilelsepop:
 813           MAYBE_GC ();
 814           op = *stack.pc++;
 815           if (NILP (TOP))
 816             {
 817               BYTE_CODE_QUIT;
 818               stack.pc += op - 128;
 819             }
 820           else DISCARD (1);
 821           break;
 822
 823         case BRgotoifnonnilelsepop:
 824           MAYBE_GC ();
 825           op = *stack.pc++;
 826           if (!NILP (TOP))
 827             {
 828               BYTE_CODE_QUIT;
 829               stack.pc += op - 128;
 830             }
 831           else DISCARD (1);
 832           break;
 833
 834         case Breturn:
 835           result = POP;
 836           goto exit;
 837
 838         case Bdiscard:
 839           DISCARD (1);
 840           break;
 841
 842         case Bconstant2:
 843           PUSH (vectorp[FETCH2]);
 844           break;
 845
 846         case Bsave_excursion:
 847           record_unwind_protect (save_excursion_restore,
 848                                  save_excursion_save ());
 849           break;
 850
 851         case Bsave_current_buffer:
 852         case Bsave_current_buffer_1:
 853           record_unwind_protect (set_buffer_if_live, Fcurrent_buffer ());
 854           break;
 855
 856         case Bsave_window_excursion:
 857           BEFORE_POTENTIAL_GC ();
 858           TOP = Fsave_window_excursion (TOP);
 859           AFTER_POTENTIAL_GC ();
 860           break;
 861
 862         case Bsave_restriction:
 863           record_unwind_protect (save_restriction_restore,
 864                                  save_restriction_save ());
 865           break;
 866
 867         case Bcatch:
 868           {
 869             Lisp_Object v1;
 870             BEFORE_POTENTIAL_GC ();
 871             v1 = POP;
 872             TOP = internal_catch (TOP, Feval, v1);
 873             AFTER_POTENTIAL_GC ();
 874             break;
 875           }
 876
 877         case Bunwind_protect:
 878           /* The function record_unwind_protect can GC.  */
 879           BEFORE_POTENTIAL_GC ();
 880           record_unwind_protect (Fprogn, POP);
 881           AFTER_POTENTIAL_GC ();
 882           break;
 883
 884         case Bcondition_case:
 885           {
 886             Lisp_Object v1;
 887             v1 = POP;
 888             v1 = Fcons (POP, v1);
 889             BEFORE_POTENTIAL_GC ();
 890             TOP = Fcondition_case (Fcons (TOP, v1));
 891             AFTER_POTENTIAL_GC ();
 892             break;
 893           }
 894
 895         case Btemp_output_buffer_setup:
 896           BEFORE_POTENTIAL_GC ();
 897           CHECK_STRING (TOP);
 898           temp_output_buffer_setup (SDATA (TOP));
 899           AFTER_POTENTIAL_GC ();
 900           TOP = Vstandard_output;
 901           break;
 902
 903         case Btemp_output_buffer_show:
 904           {
 905             Lisp_Object v1;
 906             BEFORE_POTENTIAL_GC ();
 907             v1 = POP;
 908             temp_output_buffer_show (TOP);
 909             TOP = v1;
 910             /* pop binding of standard-output */
 911             unbind_to (SPECPDL_INDEX () - 1, Qnil);
 912             AFTER_POTENTIAL_GC ();
 913             break;
 914           }
 915
 916         case Bnth:
 917           {
 918             Lisp_Object v1, v2;
 919             BEFORE_POTENTIAL_GC ();
 920             v1 = POP;
 921             v2 = TOP;
 922             CHECK_NUMBER (v2);
 923             AFTER_POTENTIAL_GC ();
 924             op = XINT (v2);
 925             immediate_quit = 1;
 926             while (--op >= 0)
 927               {
 928                 if (CONSP (v1))
 929                   v1 = XCDR (v1);
 930                 else if (!NILP (v1))
 931                   {
 932                     immediate_quit = 0;
 933                     BEFORE_POTENTIAL_GC ();
 934                     v1 = wrong_type_argument (Qlistp, v1);
 935                     AFTER_POTENTIAL_GC ();
 936                     immediate_quit = 1;
 937                     op++;
 938                   }
 939               }
 940             immediate_quit = 0;
 941             if (CONSP (v1))
 942               TOP = XCAR (v1);
 943             else if (NILP (v1))
 944               TOP = Qnil;
 945             else
 946               {
 947                 BEFORE_POTENTIAL_GC ();
 948                 Fcar (wrong_type_argument (Qlistp, v1));
 949                 AFTER_POTENTIAL_GC ();
 950               }
 951             break;
 952           }
 953
 954         case Bsymbolp:
 955           TOP = SYMBOLP (TOP) ? Qt : Qnil;
 956           break;
 957
 958         case Bconsp:
 959           TOP = CONSP (TOP) ? Qt : Qnil;
 960           break;
 961
 962         case Bstringp:
 963           TOP = STRINGP (TOP) ? Qt : Qnil;
 964           break;
 965
 966         case Blistp:
 967           TOP = CONSP (TOP) || NILP (TOP) ? Qt : Qnil;
 968           break;
 969
 970         case Bnot:
 971           TOP = NILP (TOP) ? Qt : Qnil;
 972           break;
 973
 974         case Bcons:
 975           {
 976             Lisp_Object v1;
 977             v1 = POP;
 978             TOP = Fcons (TOP, v1);
 979             break;
 980           }
 981
 982         case Blist1:
 983           TOP = Fcons (TOP, Qnil);
 984           break;
 985
 986         case Blist2:
 987           {
 988             Lisp_Object v1;
 989             v1 = POP;
 990             TOP = Fcons (TOP, Fcons (v1, Qnil));
 991             break;
 992           }
 993
 994         case Blist3:
 995           DISCARD (2);
 996           TOP = Flist (3, &TOP);
 997           break;
 998
 999         case Blist4:
1000           DISCARD (3);
1001           TOP = Flist (4, &TOP);
1002           break;
1003
1004         case BlistN:
1005           op = FETCH;
1006           DISCARD (op - 1);
1007           TOP = Flist (op, &TOP);
1008           break;
1009
1010         case Blength:
1011           BEFORE_POTENTIAL_GC ();
1012           TOP = Flength (TOP);
1013           AFTER_POTENTIAL_GC ();
1014           break;
1015
1016         case Baref:
1017           {
1018             Lisp_Object v1;
1019             BEFORE_POTENTIAL_GC ();
1020             v1 = POP;
1021             TOP = Faref (TOP, v1);
1022             AFTER_POTENTIAL_GC ();
1023             break;
1024           }
1025
1026         case Baset:
1027           {
1028             Lisp_Object v1, v2;
1029             BEFORE_POTENTIAL_GC ();
1030             v2 = POP; v1 = POP;
1031             TOP = Faset (TOP, v1, v2);
1032             AFTER_POTENTIAL_GC ();
1033             break;
1034           }
1035
1036         case Bsymbol_value:
1037           BEFORE_POTENTIAL_GC ();
1038           TOP = Fsymbol_value (TOP);
1039           AFTER_POTENTIAL_GC ();
1040           break;
1041
1042         case Bsymbol_function:
1043           BEFORE_POTENTIAL_GC ();
1044           TOP = Fsymbol_function (TOP);
1045           AFTER_POTENTIAL_GC ();
1046           break;
1047
1048         case Bset:
1049           {
1050             Lisp_Object v1;
1051             BEFORE_POTENTIAL_GC ();
1052             v1 = POP;
1053             TOP = Fset (TOP, v1);
1054             AFTER_POTENTIAL_GC ();
1055             break;
1056           }
1057
1058         case Bfset:
1059           {
1060             Lisp_Object v1;
1061             BEFORE_POTENTIAL_GC ();
1062             v1 = POP;
1063             TOP = Ffset (TOP, v1);
1064             AFTER_POTENTIAL_GC ();
1065             break;
1066           }
1067
1068         case Bget:
1069           {
1070             Lisp_Object v1;
1071             BEFORE_POTENTIAL_GC ();
1072             v1 = POP;
1073             TOP = Fget (TOP, v1);
1074             AFTER_POTENTIAL_GC ();
1075             break;
1076           }
1077
1078         case Bsubstring:
1079           {
1080             Lisp_Object v1, v2;
1081             BEFORE_POTENTIAL_GC ();
1082             v2 = POP; v1 = POP;
1083             TOP = Fsubstring (TOP, v1, v2);
1084             AFTER_POTENTIAL_GC ();
1085             break;
1086           }
1087
1088         case Bconcat2:
1089           BEFORE_POTENTIAL_GC ();
1090           DISCARD (1);
1091           TOP = Fconcat (2, &TOP);
1092           AFTER_POTENTIAL_GC ();
1093           break;
1094
1095         case Bconcat3:
1096           BEFORE_POTENTIAL_GC ();
1097           DISCARD (2);
1098           TOP = Fconcat (3, &TOP);
1099           AFTER_POTENTIAL_GC ();
1100           break;
1101
1102         case Bconcat4:
1103           BEFORE_POTENTIAL_GC ();
1104           DISCARD (3);
1105           TOP = Fconcat (4, &TOP);
1106           AFTER_POTENTIAL_GC ();
1107           break;
1108
1109         case BconcatN:
1110           op = FETCH;
1111           BEFORE_POTENTIAL_GC ();
1112           DISCARD (op - 1);
1113           TOP = Fconcat (op, &TOP);
1114           AFTER_POTENTIAL_GC ();
1115           break;
1116
1117         case Bsub1:
1118           {
1119             Lisp_Object v1;
1120             v1 = TOP;
1121             if (INTEGERP (v1))
1122               {
1123                 XSETINT (v1, XINT (v1) - 1);
1124                 TOP = v1;
1125               }
1126             else
1127               {
1128                 BEFORE_POTENTIAL_GC ();
1129                 TOP = Fsub1 (v1);
1130                 AFTER_POTENTIAL_GC ();
1131               }
1132             break;
1133           }
1134
1135         case Badd1:
1136           {
1137             Lisp_Object v1;
1138             v1 = TOP;
1139             if (INTEGERP (v1))
1140               {
1141                 XSETINT (v1, XINT (v1) + 1);
1142                 TOP = v1;
1143               }
1144             else
1145               {
1146                 BEFORE_POTENTIAL_GC ();
1147                 TOP = Fadd1 (v1);
1148                 AFTER_POTENTIAL_GC ();
1149               }
1150             break;
1151           }
1152
1153         case Beqlsign:
1154           {
1155             Lisp_Object v1, v2;
1156             BEFORE_POTENTIAL_GC ();
1157             v2 = POP; v1 = TOP;
1158             CHECK_NUMBER_OR_FLOAT_COERCE_MARKER (v1);
1159             CHECK_NUMBER_OR_FLOAT_COERCE_MARKER (v2);
1160             AFTER_POTENTIAL_GC ();
1161             if (FLOATP (v1) || FLOATP (v2))
1162               {
1163                 double f1, f2;
1164
1165                 f1 = (FLOATP (v1) ? XFLOAT_DATA (v1) : XINT (v1));
1166                 f2 = (FLOATP (v2) ? XFLOAT_DATA (v2) : XINT (v2));
1167                 TOP = (f1 == f2 ? Qt : Qnil);
1168               }
1169             else
1170               TOP = (XINT (v1) == XINT (v2) ? Qt : Qnil);
1171             break;
1172           }
1173
1174         case Bgtr:
1175           {
1176             Lisp_Object v1;
1177             BEFORE_POTENTIAL_GC ();
1178             v1 = POP;
1179             TOP = Fgtr (TOP, v1);
1180             AFTER_POTENTIAL_GC ();
1181             break;
1182           }
1183
1184         case Blss:
1185           {
1186             Lisp_Object v1;
1187             BEFORE_POTENTIAL_GC ();
1188             v1 = POP;
1189             TOP = Flss (TOP, v1);
1190             AFTER_POTENTIAL_GC ();
1191             break;
1192           }
1193
1194         case Bleq:
1195           {
1196             Lisp_Object v1;
1197             BEFORE_POTENTIAL_GC ();
1198             v1 = POP;
1199             TOP = Fleq (TOP, v1);
1200             AFTER_POTENTIAL_GC ();
1201             break;
1202           }
1203
1204         case Bgeq:
1205           {
1206             Lisp_Object v1;
1207             BEFORE_POTENTIAL_GC ();
1208             v1 = POP;
1209             TOP = Fgeq (TOP, v1);
1210             AFTER_POTENTIAL_GC ();
1211             break;
1212           }
1213
1214         case Bdiff:
1215           BEFORE_POTENTIAL_GC ();
1216           DISCARD (1);
1217           TOP = Fminus (2, &TOP);
1218           AFTER_POTENTIAL_GC ();
1219           break;
1220
1221         case Bnegate:
1222           {
1223             Lisp_Object v1;
1224             v1 = TOP;
1225             if (INTEGERP (v1))
1226               {
1227                 XSETINT (v1, - XINT (v1));
1228                 TOP = v1;
1229               }
1230             else
1231               {
1232                 BEFORE_POTENTIAL_GC ();
1233                 TOP = Fminus (1, &TOP);
1234                 AFTER_POTENTIAL_GC ();
1235               }
1236             break;
1237           }
1238
1239         case Bplus:
1240           BEFORE_POTENTIAL_GC ();
1241           DISCARD (1);
1242           TOP = Fplus (2, &TOP);
1243           AFTER_POTENTIAL_GC ();
1244           break;
1245
1246         case Bmax:
1247           BEFORE_POTENTIAL_GC ();
1248           DISCARD (1);
1249           TOP = Fmax (2, &TOP);
1250           AFTER_POTENTIAL_GC ();
1251           break;
1252
1253         case Bmin:
1254           BEFORE_POTENTIAL_GC ();
1255           DISCARD (1);
1256           TOP = Fmin (2, &TOP);
1257           AFTER_POTENTIAL_GC ();
1258           break;
1259
1260         case Bmult:
1261           BEFORE_POTENTIAL_GC ();
1262           DISCARD (1);
1263           TOP = Ftimes (2, &TOP);
1264           AFTER_POTENTIAL_GC ();
1265           break;
1266
1267         case Bquo:
1268           BEFORE_POTENTIAL_GC ();
1269           DISCARD (1);
1270           TOP = Fquo (2, &TOP);
1271           AFTER_POTENTIAL_GC ();
1272           break;
1273
1274         case Brem:
1275           {
1276             Lisp_Object v1;
1277             BEFORE_POTENTIAL_GC ();
1278             v1 = POP;
1279             TOP = Frem (TOP, v1);
1280             AFTER_POTENTIAL_GC ();
1281             break;
1282           }
1283
1284         case Bpoint:
1285           {
1286             Lisp_Object v1;
1287             XSETFASTINT (v1, PT);
1288             PUSH (v1);
1289             break;
1290           }
1291
1292         case Bgoto_char:
1293           BEFORE_POTENTIAL_GC ();
1294           TOP = Fgoto_char (TOP);
1295           AFTER_POTENTIAL_GC ();
1296           break;
1297
1298         case Binsert:
1299           BEFORE_POTENTIAL_GC ();
1300           TOP = Finsert (1, &TOP);
1301           AFTER_POTENTIAL_GC ();
1302           break;
1303
1304         case BinsertN:
1305           op = FETCH;
1306           BEFORE_POTENTIAL_GC ();
1307           DISCARD (op - 1);
1308           TOP = Finsert (op, &TOP);
1309           AFTER_POTENTIAL_GC ();
1310           break;
1311
1312         case Bpoint_max:
1313           {
1314             Lisp_Object v1;
1315             XSETFASTINT (v1, ZV);
1316             PUSH (v1);
1317             break;
1318           }
1319
1320         case Bpoint_min:
1321           {
1322             Lisp_Object v1;
1323             XSETFASTINT (v1, BEGV);
1324             PUSH (v1);
1325             break;
1326           }
1327
1328         case Bchar_after:
1329           BEFORE_POTENTIAL_GC ();
1330           TOP = Fchar_after (TOP);
1331           AFTER_POTENTIAL_GC ();
1332           break;
1333
1334         case Bfollowing_char:
1335           {
1336             Lisp_Object v1;
1337             BEFORE_POTENTIAL_GC ();
1338             v1 = Ffollowing_char ();
1339             AFTER_POTENTIAL_GC ();
1340             PUSH (v1);
1341             break;
1342           }
1343
1344         case Bpreceding_char:
1345           {
1346             Lisp_Object v1;
1347             BEFORE_POTENTIAL_GC ();
1348             v1 = Fprevious_char ();
1349             AFTER_POTENTIAL_GC ();
1350             PUSH (v1);
1351             break;
1352           }
1353
1354         case Bcurrent_column:
1355           {
1356             Lisp_Object v1;
1357             BEFORE_POTENTIAL_GC ();
1358             XSETFASTINT (v1, (int) current_column ()); /* iftc */
1359             AFTER_POTENTIAL_GC ();
1360             PUSH (v1);
1361             break;
1362           }
1363
1364         case Bindent_to:
1365           BEFORE_POTENTIAL_GC ();
1366           TOP = Findent_to (TOP, Qnil);
1367           AFTER_POTENTIAL_GC ();
1368           break;
1369
1370         case Beolp:
1371           PUSH (Feolp ());
1372           break;
1373
1374         case Beobp:
1375           PUSH (Feobp ());
1376           break;
1377
1378         case Bbolp:
1379           PUSH (Fbolp ());
1380           break;
1381
1382         case Bbobp:
1383           PUSH (Fbobp ());
1384           break;
1385
1386         case Bcurrent_buffer:
1387           PUSH (Fcurrent_buffer ());
1388           break;
1389
1390         case Bset_buffer:
1391           BEFORE_POTENTIAL_GC ();
1392           TOP = Fset_buffer (TOP);
1393           AFTER_POTENTIAL_GC ();
1394           break;
1395
1396         case Binteractive_p:
1397           PUSH (Finteractive_p ());
1398           break;
1399
1400         case Bforward_char:
1401           BEFORE_POTENTIAL_GC ();
1402           TOP = Fforward_char (TOP);
1403           AFTER_POTENTIAL_GC ();
1404           break;
1405
1406         case Bforward_word:
1407           BEFORE_POTENTIAL_GC ();
1408           TOP = Fforward_word (TOP);
1409           AFTER_POTENTIAL_GC ();
1410           break;
1411
1412         case Bskip_chars_forward:
1413           {
1414             Lisp_Object v1;
1415             BEFORE_POTENTIAL_GC ();
1416             v1 = POP;
1417             TOP = Fskip_chars_forward (TOP, v1);
1418             AFTER_POTENTIAL_GC ();
1419             break;
1420           }
1421
1422         case Bskip_chars_backward:
1423           {
1424             Lisp_Object v1;
1425             BEFORE_POTENTIAL_GC ();
1426             v1 = POP;
1427             TOP = Fskip_chars_backward (TOP, v1);
1428             AFTER_POTENTIAL_GC ();
1429             break;
1430           }
1431
1432         case Bforward_line:
1433           BEFORE_POTENTIAL_GC ();
1434           TOP = Fforward_line (TOP);
1435           AFTER_POTENTIAL_GC ();
1436           break;
1437
1438         case Bchar_syntax:
1439           BEFORE_POTENTIAL_GC ();
1440           CHECK_NUMBER (TOP);
1441           AFTER_POTENTIAL_GC ();
1442           XSETFASTINT (TOP, syntax_code_spec[(int) SYNTAX (XINT (TOP))]);
1443           break;
1444
1445         case Bbuffer_substring:
1446           {
1447             Lisp_Object v1;
1448             BEFORE_POTENTIAL_GC ();
1449             v1 = POP;
1450             TOP = Fbuffer_substring (TOP, v1);
1451             AFTER_POTENTIAL_GC ();
1452             break;
1453           }
1454
1455         case Bdelete_region:
1456           {
1457             Lisp_Object v1;
1458             BEFORE_POTENTIAL_GC ();
1459             v1 = POP;
1460             TOP = Fdelete_region (TOP, v1);
1461             AFTER_POTENTIAL_GC ();
1462             break;
1463           }
1464
1465         case Bnarrow_to_region:
1466           {
1467             Lisp_Object v1;
1468             BEFORE_POTENTIAL_GC ();
1469             v1 = POP;
1470             TOP = Fnarrow_to_region (TOP, v1);
1471             AFTER_POTENTIAL_GC ();
1472             break;
1473           }
1474
1475         case Bwiden:
1476           BEFORE_POTENTIAL_GC ();
1477           PUSH (Fwiden ());
1478           AFTER_POTENTIAL_GC ();
1479           break;
1480
1481         case Bend_of_line:
1482           BEFORE_POTENTIAL_GC ();
1483           TOP = Fend_of_line (TOP);
1484           AFTER_POTENTIAL_GC ();
1485           break;
1486
1487         case Bset_marker:
1488           {
1489             Lisp_Object v1, v2;
1490             BEFORE_POTENTIAL_GC ();
1491             v1 = POP;
1492             v2 = POP;
1493             TOP = Fset_marker (TOP, v2, v1);
1494             AFTER_POTENTIAL_GC ();
1495             break;
1496           }
1497
1498         case Bmatch_beginning:
1499           BEFORE_POTENTIAL_GC ();
1500           TOP = Fmatch_beginning (TOP);
1501           AFTER_POTENTIAL_GC ();
1502           break;
1503
1504         case Bmatch_end:
1505           BEFORE_POTENTIAL_GC ();
1506           TOP = Fmatch_end (TOP);
1507           AFTER_POTENTIAL_GC ();
1508           break;
1509
1510         case Bupcase:
1511           BEFORE_POTENTIAL_GC ();
1512           TOP = Fupcase (TOP);
1513           AFTER_POTENTIAL_GC ();
1514           break;
1515
1516         case Bdowncase:
1517           BEFORE_POTENTIAL_GC ();
1518           TOP = Fdowncase (TOP);
1519           AFTER_POTENTIAL_GC ();
1520         break;
1521
1522         case Bstringeqlsign:
1523           {
1524             Lisp_Object v1;
1525             BEFORE_POTENTIAL_GC ();
1526             v1 = POP;
1527             TOP = Fstring_equal (TOP, v1);
1528             AFTER_POTENTIAL_GC ();
1529             break;
1530           }
1531
1532         case Bstringlss:
1533           {
1534             Lisp_Object v1;
1535             BEFORE_POTENTIAL_GC ();
1536             v1 = POP;
1537             TOP = Fstring_lessp (TOP, v1);
1538             AFTER_POTENTIAL_GC ();
1539             break;
1540           }
1541
1542         case Bequal:
1543           {
1544             Lisp_Object v1;
1545             v1 = POP;
1546             TOP = Fequal (TOP, v1);
1547             break;
1548           }
1549
1550         case Bnthcdr:
1551           {
1552             Lisp_Object v1;
1553             BEFORE_POTENTIAL_GC ();
1554             v1 = POP;
1555             TOP = Fnthcdr (TOP, v1);
1556             AFTER_POTENTIAL_GC ();
1557             break;
1558           }
1559
1560         case Belt:
1561           {
1562             Lisp_Object v1, v2;
1563             if (CONSP (TOP))
1564               {
1565                 /* Exchange args and then do nth.  */
1566                 BEFORE_POTENTIAL_GC ();
1567                 v2 = POP;
1568                 v1 = TOP;
1569                 CHECK_NUMBER (v2);
1570                 AFTER_POTENTIAL_GC ();
1571                 op = XINT (v2);
1572                 immediate_quit = 1;
1573                 while (--op >= 0)
1574                   {
1575                     if (CONSP (v1))
1576                       v1 = XCDR (v1);
1577                     else if (!NILP (v1))
1578                       {
1579                         immediate_quit = 0;
1580                         BEFORE_POTENTIAL_GC ();
1581                         v1 = wrong_type_argument (Qlistp, v1);
1582                         AFTER_POTENTIAL_GC ();
1583                         immediate_quit = 1;
1584                         op++;
1585                       }
1586                   }
1587                 immediate_quit = 0;
1588                 if (CONSP (v1))
1589                   TOP = XCAR (v1);
1590                 else if (NILP (v1))
1591                   TOP = Qnil;
1592                 else
1593                   {
1594                     BEFORE_POTENTIAL_GC ();
1595                     Fcar (wrong_type_argument (Qlistp, v1));
1596                     AFTER_POTENTIAL_GC ();
1597                   }
1598               }
1599             else
1600               {
1601                 BEFORE_POTENTIAL_GC ();
1602                 v1 = POP;
1603                 TOP = Felt (TOP, v1);
1604                 AFTER_POTENTIAL_GC ();
1605               }
1606             break;
1607           }
1608
1609         case Bmember:
1610           {
1611             Lisp_Object v1;
1612             BEFORE_POTENTIAL_GC ();
1613             v1 = POP;
1614             TOP = Fmember (TOP, v1);
1615             AFTER_POTENTIAL_GC ();
1616             break;
1617           }
1618
1619         case Bassq:
1620           {
1621             Lisp_Object v1;
1622             BEFORE_POTENTIAL_GC ();
1623             v1 = POP;
1624             TOP = Fassq (TOP, v1);
1625             AFTER_POTENTIAL_GC ();
1626             break;
1627           }
1628
1629         case Bnreverse:
1630           BEFORE_POTENTIAL_GC ();
1631           TOP = Fnreverse (TOP);
1632           AFTER_POTENTIAL_GC ();
1633           break;
1634
1635         case Bsetcar:
1636           {
1637             Lisp_Object v1;
1638             BEFORE_POTENTIAL_GC ();
1639             v1 = POP;
1640             TOP = Fsetcar (TOP, v1);
1641             AFTER_POTENTIAL_GC ();
1642             break;
1643           }
1644
1645         case Bsetcdr:
1646           {
1647             Lisp_Object v1;
1648             BEFORE_POTENTIAL_GC ();
1649             v1 = POP;
1650             TOP = Fsetcdr (TOP, v1);
1651             AFTER_POTENTIAL_GC ();
1652             break;
1653           }
1654
1655         case Bcar_safe:
1656           {
1657             Lisp_Object v1;
1658             v1 = TOP;
1659             if (CONSP (v1))
1660               TOP = XCAR (v1);
1661             else
1662               TOP = Qnil;
1663             break;
1664           }
1665
1666         case Bcdr_safe:
1667           {
1668             Lisp_Object v1;
1669             v1 = TOP;
1670             if (CONSP (v1))
1671               TOP = XCDR (v1);
1672             else
1673               TOP = Qnil;
1674             break;
1675           }
1676
1677         case Bnconc:
1678           BEFORE_POTENTIAL_GC ();
1679           DISCARD (1);
1680           TOP = Fnconc (2, &TOP);
1681           AFTER_POTENTIAL_GC ();
1682           break;
1683
1684         case Bnumberp:
1685           TOP = (NUMBERP (TOP) ? Qt : Qnil);
1686           break;
1687
1688         case Bintegerp:
1689           TOP = INTEGERP (TOP) ? Qt : Qnil;
1690           break;
1691
1692 #ifdef BYTE_CODE_SAFE
1693         case Bset_mark:
1694           BEFORE_POTENTIAL_GC ();
1695           error ("set-mark is an obsolete bytecode");
1696           AFTER_POTENTIAL_GC ();
1697           break;
1698         case Bscan_buffer:
1699           BEFORE_POTENTIAL_GC ();
1700           error ("scan-buffer is an obsolete bytecode");
1701           AFTER_POTENTIAL_GC ();
1702           break;
1703 #endif
1704
1705         case 0:
1706           abort ();
1707
1708         case 255:
1709         default:
1710 #ifdef BYTE_CODE_SAFE
1711           if (op < Bconstant)
1712             {
1713               abort ();
1714             }
1715           if ((op -= Bconstant) >= const_length)
1716             {
1717               abort ();
1718             }
1719           PUSH (vectorp[op]);
1720 #else
1721           PUSH (vectorp[op - Bconstant]);
1722 #endif
1723         }
1724     }
1725
1726  exit:
1727
1728   byte_stack_list = byte_stack_list->next;
1729
1730   /* Binds and unbinds are supposed to be compiled balanced.  */
1731   if (SPECPDL_INDEX () != count)
1732 #ifdef BYTE_CODE_SAFE
1733     error ("binding stack not balanced (serious byte compiler bug)");
1734 #else
1735     abort ();
1736 #endif
1737
1738   return result;
1739 }
1740
1741 void
1742 syms_of_bytecode ()
1743 {
1744   Qbytecode = intern ("byte-code");
1745   staticpro (&Qbytecode);
1746
1747   defsubr (&Sbyte_code);
1748
1749 #ifdef BYTE_CODE_METER
1750
1751   DEFVAR_LISP ("byte-code-meter", &Vbyte_code_meter,
1752                doc: /* A vector of vectors which holds a histogram of byte-code usage.
1753 \(aref (aref byte-code-meter 0) CODE) indicates how many times the byte
1754 opcode CODE has been executed.
1755 \(aref (aref byte-code-meter CODE1) CODE2), where CODE1 is not 0,
1756 indicates how many times the byte opcodes CODE1 and CODE2 have been
1757 executed in succession.  */);
1758
1759   DEFVAR_BOOL ("byte-metering-on", &byte_metering_on,
1760                doc: /* If non-nil, keep profiling information on byte code usage.
1761 The variable byte-code-meter indicates how often each byte opcode is used.
1762 If a symbol has a property named `byte-code-meter' whose value is an
1763 integer, it is incremented each time that symbol's function is called.  */);
1764
1765   byte_metering_on = 0;
1766   Vbyte_code_meter = Fmake_vector (make_number (256), make_number (0));
1767   Qbyte_code_meter = intern ("byte-code-meter");
1768   staticpro (&Qbyte_code_meter);
1769   {
1770     int i = 256;
1771     while (i--)
1772       XVECTOR (Vbyte_code_meter)->contents[i] =
1773         Fmake_vector (make_number (256), make_number (0));
1774   }
1775 #endif
1776 }