Source

aotus / external / lua-5.2.2 / src / lgc.c

Full commit
   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
/*
** $Id: lgc.c,v 2.140 2013/03/16 21:10:18 roberto Exp $
** Garbage Collector
** See Copyright Notice in lua.h
*/

#include <string.h>

#define lgc_c
#define LUA_CORE

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"



/*
** cost of sweeping one element (the size of a small object divided
** by some adjust for the sweep speed)
*/
#define GCSWEEPCOST	((sizeof(TString) + 4) / 4)

/* maximum number of elements to sweep in each single step */
#define GCSWEEPMAX	(cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))

/* maximum number of finalizers to call in each GC step */
#define GCFINALIZENUM	4


/*
** macro to adjust 'stepmul': 'stepmul' is actually used like
** 'stepmul / STEPMULADJ' (value chosen by tests)
*/
#define STEPMULADJ		200


/*
** macro to adjust 'pause': 'pause' is actually used like
** 'pause / PAUSEADJ' (value chosen by tests)
*/
#define PAUSEADJ		100


/*
** 'makewhite' erases all color bits plus the old bit and then
** sets only the current white bit
*/
#define maskcolors	(~(bit2mask(BLACKBIT, OLDBIT) | WHITEBITS))
#define makewhite(g,x)	\
 (gch(x)->marked = cast_byte((gch(x)->marked & maskcolors) | luaC_white(g)))

#define white2gray(x)	resetbits(gch(x)->marked, WHITEBITS)
#define black2gray(x)	resetbit(gch(x)->marked, BLACKBIT)


#define isfinalized(x)		testbit(gch(x)->marked, FINALIZEDBIT)

#define checkdeadkey(n)	lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))


#define checkconsistency(obj)  \
  lua_longassert(!iscollectable(obj) || righttt(obj))


#define markvalue(g,o) { checkconsistency(o); \
  if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }

#define markobject(g,t) { if ((t) && iswhite(obj2gco(t))) \
		reallymarkobject(g, obj2gco(t)); }

static void reallymarkobject (global_State *g, GCObject *o);


/*
** {======================================================
** Generic functions
** =======================================================
*/


/*
** one after last element in a hash array
*/
#define gnodelast(h)	gnode(h, cast(size_t, sizenode(h)))


/*
** link table 'h' into list pointed by 'p'
*/
#define linktable(h,p)	((h)->gclist = *(p), *(p) = obj2gco(h))


/*
** if key is not marked, mark its entry as dead (therefore removing it
** from the table)
*/
static void removeentry (Node *n) {
  lua_assert(ttisnil(gval(n)));
  if (valiswhite(gkey(n)))
    setdeadvalue(gkey(n));  /* unused and unmarked key; remove it */
}


/*
** tells whether a key or value can be cleared from a weak
** table. Non-collectable objects are never removed from weak
** tables. Strings behave as `values', so are never removed too. for
** other objects: if really collected, cannot keep them; for objects
** being finalized, keep them in keys, but not in values
*/
static int iscleared (global_State *g, const TValue *o) {
  if (!iscollectable(o)) return 0;
  else if (ttisstring(o)) {
    markobject(g, rawtsvalue(o));  /* strings are `values', so are never weak */
    return 0;
  }
  else return iswhite(gcvalue(o));
}


/*
** barrier that moves collector forward, that is, mark the white object
** being pointed by a black object.
*/
void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
  global_State *g = G(L);
  lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o));
  lua_assert(g->gcstate != GCSpause);
  lua_assert(gch(o)->tt != LUA_TTABLE);
  if (keepinvariantout(g))  /* must keep invariant? */
    reallymarkobject(g, v);  /* restore invariant */
  else {  /* sweep phase */
    lua_assert(issweepphase(g));
    makewhite(g, o);  /* mark main obj. as white to avoid other barriers */
  }
}


/*
** barrier that moves collector backward, that is, mark the black object
** pointing to a white object as gray again. (Current implementation
** only works for tables; access to 'gclist' is not uniform across
** different types.)
*/
void luaC_barrierback_ (lua_State *L, GCObject *o) {
  global_State *g = G(L);
  lua_assert(isblack(o) && !isdead(g, o) && gch(o)->tt == LUA_TTABLE);
  black2gray(o);  /* make object gray (again) */
  gco2t(o)->gclist = g->grayagain;
  g->grayagain = o;
}


/*
** barrier for prototypes. When creating first closure (cache is
** NULL), use a forward barrier; this may be the only closure of the
** prototype (if it is a "regular" function, with a single instance)
** and the prototype may be big, so it is better to avoid traversing
** it again. Otherwise, use a backward barrier, to avoid marking all
** possible instances.
*/
LUAI_FUNC void luaC_barrierproto_ (lua_State *L, Proto *p, Closure *c) {
  global_State *g = G(L);
  lua_assert(isblack(obj2gco(p)));
  if (p->cache == NULL) {  /* first time? */
    luaC_objbarrier(L, p, c);
  }
  else {  /* use a backward barrier */
    black2gray(obj2gco(p));  /* make prototype gray (again) */
    p->gclist = g->grayagain;
    g->grayagain = obj2gco(p);
  }
}


/*
** check color (and invariants) for an upvalue that was closed,
** i.e., moved into the 'allgc' list
*/
void luaC_checkupvalcolor (global_State *g, UpVal *uv) {
  GCObject *o = obj2gco(uv);
  lua_assert(!isblack(o));  /* open upvalues are never black */
  if (isgray(o)) {
    if (keepinvariant(g)) {
      resetoldbit(o);  /* see MOVE OLD rule */
      gray2black(o);  /* it is being visited now */
      markvalue(g, uv->v);
    }
    else {
      lua_assert(issweepphase(g));
      makewhite(g, o);
    }
  }
}


/*
** create a new collectable object (with given type and size) and link
** it to '*list'. 'offset' tells how many bytes to allocate before the
** object itself (used only by states).
*/
GCObject *luaC_newobj (lua_State *L, int tt, size_t sz, GCObject **list,
                       int offset) {
  global_State *g = G(L);
  char *raw = cast(char *, luaM_newobject(L, novariant(tt), sz));
  GCObject *o = obj2gco(raw + offset);
  if (list == NULL)
    list = &g->allgc;  /* standard list for collectable objects */
  gch(o)->marked = luaC_white(g);
  gch(o)->tt = tt;
  gch(o)->next = *list;
  *list = o;
  return o;
}

/* }====================================================== */



/*
** {======================================================
** Mark functions
** =======================================================
*/


/*
** mark an object. Userdata, strings, and closed upvalues are visited
** and turned black here. Other objects are marked gray and added
** to appropriate list to be visited (and turned black) later. (Open
** upvalues are already linked in 'headuv' list.)
*/
static void reallymarkobject (global_State *g, GCObject *o) {
  lu_mem size;
  white2gray(o);
  switch (gch(o)->tt) {
    case LUA_TSHRSTR:
    case LUA_TLNGSTR: {
      size = sizestring(gco2ts(o));
      break;  /* nothing else to mark; make it black */
    }
    case LUA_TUSERDATA: {
      Table *mt = gco2u(o)->metatable;
      markobject(g, mt);
      markobject(g, gco2u(o)->env);
      size = sizeudata(gco2u(o));
      break;
    }
    case LUA_TUPVAL: {
      UpVal *uv = gco2uv(o);
      markvalue(g, uv->v);
      if (uv->v != &uv->u.value)  /* open? */
        return;  /* open upvalues remain gray */
      size = sizeof(UpVal);
      break;
    }
    case LUA_TLCL: {
      gco2lcl(o)->gclist = g->gray;
      g->gray = o;
      return;
    }
    case LUA_TCCL: {
      gco2ccl(o)->gclist = g->gray;
      g->gray = o;
      return;
    }
    case LUA_TTABLE: {
      linktable(gco2t(o), &g->gray);
      return;
    }
    case LUA_TTHREAD: {
      gco2th(o)->gclist = g->gray;
      g->gray = o;
      return;
    }
    case LUA_TPROTO: {
      gco2p(o)->gclist = g->gray;
      g->gray = o;
      return;
    }
    default: lua_assert(0); return;
  }
  gray2black(o);
  g->GCmemtrav += size;
}


/*
** mark metamethods for basic types
*/
static void markmt (global_State *g) {
  int i;
  for (i=0; i < LUA_NUMTAGS; i++)
    markobject(g, g->mt[i]);
}


/*
** mark all objects in list of being-finalized
*/
static void markbeingfnz (global_State *g) {
  GCObject *o;
  for (o = g->tobefnz; o != NULL; o = gch(o)->next) {
    makewhite(g, o);
    reallymarkobject(g, o);
  }
}


/*
** mark all values stored in marked open upvalues. (See comment in
** 'lstate.h'.)
*/
static void remarkupvals (global_State *g) {
  UpVal *uv;
  for (uv = g->uvhead.u.l.next; uv != &g->uvhead; uv = uv->u.l.next) {
    if (isgray(obj2gco(uv)))
      markvalue(g, uv->v);
  }
}


/*
** mark root set and reset all gray lists, to start a new
** incremental (or full) collection
*/
static void restartcollection (global_State *g) {
  g->gray = g->grayagain = NULL;
  g->weak = g->allweak = g->ephemeron = NULL;
  markobject(g, g->mainthread);
  markvalue(g, &g->l_registry);
  markmt(g);
  markbeingfnz(g);  /* mark any finalizing object left from previous cycle */
}

/* }====================================================== */


/*
** {======================================================
** Traverse functions
** =======================================================
*/

static void traverseweakvalue (global_State *g, Table *h) {
  Node *n, *limit = gnodelast(h);
  /* if there is array part, assume it may have white values (do not
     traverse it just to check) */
  int hasclears = (h->sizearray > 0);
  for (n = gnode(h, 0); n < limit; n++) {
    checkdeadkey(n);
    if (ttisnil(gval(n)))  /* entry is empty? */
      removeentry(n);  /* remove it */
    else {
      lua_assert(!ttisnil(gkey(n)));
      markvalue(g, gkey(n));  /* mark key */
      if (!hasclears && iscleared(g, gval(n)))  /* is there a white value? */
        hasclears = 1;  /* table will have to be cleared */
    }
  }
  if (hasclears)
    linktable(h, &g->weak);  /* has to be cleared later */
  else  /* no white values */
    linktable(h, &g->grayagain);  /* no need to clean */
}


static int traverseephemeron (global_State *g, Table *h) {
  int marked = 0;  /* true if an object is marked in this traversal */
  int hasclears = 0;  /* true if table has white keys */
  int prop = 0;  /* true if table has entry "white-key -> white-value" */
  Node *n, *limit = gnodelast(h);
  int i;
  /* traverse array part (numeric keys are 'strong') */
  for (i = 0; i < h->sizearray; i++) {
    if (valiswhite(&h->array[i])) {
      marked = 1;
      reallymarkobject(g, gcvalue(&h->array[i]));
    }
  }
  /* traverse hash part */
  for (n = gnode(h, 0); n < limit; n++) {
    checkdeadkey(n);
    if (ttisnil(gval(n)))  /* entry is empty? */
      removeentry(n);  /* remove it */
    else if (iscleared(g, gkey(n))) {  /* key is not marked (yet)? */
      hasclears = 1;  /* table must be cleared */
      if (valiswhite(gval(n)))  /* value not marked yet? */
        prop = 1;  /* must propagate again */
    }
    else if (valiswhite(gval(n))) {  /* value not marked yet? */
      marked = 1;
      reallymarkobject(g, gcvalue(gval(n)));  /* mark it now */
    }
  }
  if (prop)
    linktable(h, &g->ephemeron);  /* have to propagate again */
  else if (hasclears)  /* does table have white keys? */
    linktable(h, &g->allweak);  /* may have to clean white keys */
  else  /* no white keys */
    linktable(h, &g->grayagain);  /* no need to clean */
  return marked;
}


static void traversestrongtable (global_State *g, Table *h) {
  Node *n, *limit = gnodelast(h);
  int i;
  for (i = 0; i < h->sizearray; i++)  /* traverse array part */
    markvalue(g, &h->array[i]);
  for (n = gnode(h, 0); n < limit; n++) {  /* traverse hash part */
    checkdeadkey(n);
    if (ttisnil(gval(n)))  /* entry is empty? */
      removeentry(n);  /* remove it */
    else {
      lua_assert(!ttisnil(gkey(n)));
      markvalue(g, gkey(n));  /* mark key */
      markvalue(g, gval(n));  /* mark value */
    }
  }
}


static lu_mem traversetable (global_State *g, Table *h) {
  const char *weakkey, *weakvalue;
  const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
  markobject(g, h->metatable);
  if (mode && ttisstring(mode) &&  /* is there a weak mode? */
      ((weakkey = strchr(svalue(mode), 'k')),
       (weakvalue = strchr(svalue(mode), 'v')),
       (weakkey || weakvalue))) {  /* is really weak? */
    black2gray(obj2gco(h));  /* keep table gray */
    if (!weakkey)  /* strong keys? */
      traverseweakvalue(g, h);
    else if (!weakvalue)  /* strong values? */
      traverseephemeron(g, h);
    else  /* all weak */
      linktable(h, &g->allweak);  /* nothing to traverse now */
  }
  else  /* not weak */
    traversestrongtable(g, h);
  return sizeof(Table) + sizeof(TValue) * h->sizearray +
                         sizeof(Node) * cast(size_t, sizenode(h));
}


static int traverseproto (global_State *g, Proto *f) {
  int i;
  if (f->cache && iswhite(obj2gco(f->cache)))
    f->cache = NULL;  /* allow cache to be collected */
  markobject(g, f->source);
  for (i = 0; i < f->sizek; i++)  /* mark literals */
    markvalue(g, &f->k[i]);
  for (i = 0; i < f->sizeupvalues; i++)  /* mark upvalue names */
    markobject(g, f->upvalues[i].name);
  for (i = 0; i < f->sizep; i++)  /* mark nested protos */
    markobject(g, f->p[i]);
  for (i = 0; i < f->sizelocvars; i++)  /* mark local-variable names */
    markobject(g, f->locvars[i].varname);
  return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
                         sizeof(Proto *) * f->sizep +
                         sizeof(TValue) * f->sizek +
                         sizeof(int) * f->sizelineinfo +
                         sizeof(LocVar) * f->sizelocvars +
                         sizeof(Upvaldesc) * f->sizeupvalues;
}


static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
  int i;
  for (i = 0; i < cl->nupvalues; i++)  /* mark its upvalues */
    markvalue(g, &cl->upvalue[i]);
  return sizeCclosure(cl->nupvalues);
}

static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
  int i;
  markobject(g, cl->p);  /* mark its prototype */
  for (i = 0; i < cl->nupvalues; i++)  /* mark its upvalues */
    markobject(g, cl->upvals[i]);
  return sizeLclosure(cl->nupvalues);
}


static lu_mem traversestack (global_State *g, lua_State *th) {
  int n = 0;
  StkId o = th->stack;
  if (o == NULL)
    return 1;  /* stack not completely built yet */
  for (; o < th->top; o++)
    markvalue(g, o);
  if (g->gcstate == GCSatomic) {  /* final traversal? */
    StkId lim = th->stack + th->stacksize;  /* real end of stack */
    for (; o < lim; o++)  /* clear not-marked stack slice */
      setnilvalue(o);
  }
  else {  /* count call infos to compute size */
    CallInfo *ci;
    for (ci = &th->base_ci; ci != th->ci; ci = ci->next)
      n++;
  }
  return sizeof(lua_State) + sizeof(TValue) * th->stacksize +
         sizeof(CallInfo) * n;
}


/*
** traverse one gray object, turning it to black (except for threads,
** which are always gray).
*/
static void propagatemark (global_State *g) {
  lu_mem size;
  GCObject *o = g->gray;
  lua_assert(isgray(o));
  gray2black(o);
  switch (gch(o)->tt) {
    case LUA_TTABLE: {
      Table *h = gco2t(o);
      g->gray = h->gclist;  /* remove from 'gray' list */
      size = traversetable(g, h);
      break;
    }
    case LUA_TLCL: {
      LClosure *cl = gco2lcl(o);
      g->gray = cl->gclist;  /* remove from 'gray' list */
      size = traverseLclosure(g, cl);
      break;
    }
    case LUA_TCCL: {
      CClosure *cl = gco2ccl(o);
      g->gray = cl->gclist;  /* remove from 'gray' list */
      size = traverseCclosure(g, cl);
      break;
    }
    case LUA_TTHREAD: {
      lua_State *th = gco2th(o);
      g->gray = th->gclist;  /* remove from 'gray' list */
      th->gclist = g->grayagain;
      g->grayagain = o;  /* insert into 'grayagain' list */
      black2gray(o);
      size = traversestack(g, th);
      break;
    }
    case LUA_TPROTO: {
      Proto *p = gco2p(o);
      g->gray = p->gclist;  /* remove from 'gray' list */
      size = traverseproto(g, p);
      break;
    }
    default: lua_assert(0); return;
  }
  g->GCmemtrav += size;
}


static void propagateall (global_State *g) {
  while (g->gray) propagatemark(g);
}


static void propagatelist (global_State *g, GCObject *l) {
  lua_assert(g->gray == NULL);  /* no grays left */
  g->gray = l;
  propagateall(g);  /* traverse all elements from 'l' */
}

/*
** retraverse all gray lists. Because tables may be reinserted in other
** lists when traversed, traverse the original lists to avoid traversing
** twice the same table (which is not wrong, but inefficient)
*/
static void retraversegrays (global_State *g) {
  GCObject *weak = g->weak;  /* save original lists */
  GCObject *grayagain = g->grayagain;
  GCObject *ephemeron = g->ephemeron;
  g->weak = g->grayagain = g->ephemeron = NULL;
  propagateall(g);  /* traverse main gray list */
  propagatelist(g, grayagain);
  propagatelist(g, weak);
  propagatelist(g, ephemeron);
}


static void convergeephemerons (global_State *g) {
  int changed;
  do {
    GCObject *w;
    GCObject *next = g->ephemeron;  /* get ephemeron list */
    g->ephemeron = NULL;  /* tables will return to this list when traversed */
    changed = 0;
    while ((w = next) != NULL) {
      next = gco2t(w)->gclist;
      if (traverseephemeron(g, gco2t(w))) {  /* traverse marked some value? */
        propagateall(g);  /* propagate changes */
        changed = 1;  /* will have to revisit all ephemeron tables */
      }
    }
  } while (changed);
}

/* }====================================================== */


/*
** {======================================================
** Sweep Functions
** =======================================================
*/


/*
** clear entries with unmarked keys from all weaktables in list 'l' up
** to element 'f'
*/
static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
  for (; l != f; l = gco2t(l)->gclist) {
    Table *h = gco2t(l);
    Node *n, *limit = gnodelast(h);
    for (n = gnode(h, 0); n < limit; n++) {
      if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
        setnilvalue(gval(n));  /* remove value ... */
        removeentry(n);  /* and remove entry from table */
      }
    }
  }
}


/*
** clear entries with unmarked values from all weaktables in list 'l' up
** to element 'f'
*/
static void clearvalues (global_State *g, GCObject *l, GCObject *f) {
  for (; l != f; l = gco2t(l)->gclist) {
    Table *h = gco2t(l);
    Node *n, *limit = gnodelast(h);
    int i;
    for (i = 0; i < h->sizearray; i++) {
      TValue *o = &h->array[i];
      if (iscleared(g, o))  /* value was collected? */
        setnilvalue(o);  /* remove value */
    }
    for (n = gnode(h, 0); n < limit; n++) {
      if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
        setnilvalue(gval(n));  /* remove value ... */
        removeentry(n);  /* and remove entry from table */
      }
    }
  }
}


static void freeobj (lua_State *L, GCObject *o) {
  switch (gch(o)->tt) {
    case LUA_TPROTO: luaF_freeproto(L, gco2p(o)); break;
    case LUA_TLCL: {
      luaM_freemem(L, o, sizeLclosure(gco2lcl(o)->nupvalues));
      break;
    }
    case LUA_TCCL: {
      luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
      break;
    }
    case LUA_TUPVAL: luaF_freeupval(L, gco2uv(o)); break;
    case LUA_TTABLE: luaH_free(L, gco2t(o)); break;
    case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break;
    case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
    case LUA_TSHRSTR:
      G(L)->strt.nuse--;
      /* go through */
    case LUA_TLNGSTR: {
      luaM_freemem(L, o, sizestring(gco2ts(o)));
      break;
    }
    default: lua_assert(0);
  }
}


#define sweepwholelist(L,p)	sweeplist(L,p,MAX_LUMEM)
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);


/*
** sweep the (open) upvalues of a thread and resize its stack and
** list of call-info structures.
*/
static void sweepthread (lua_State *L, lua_State *L1) {
  if (L1->stack == NULL) return;  /* stack not completely built yet */
  sweepwholelist(L, &L1->openupval);  /* sweep open upvalues */
  luaE_freeCI(L1);  /* free extra CallInfo slots */
  /* should not change the stack during an emergency gc cycle */
  if (G(L)->gckind != KGC_EMERGENCY)
    luaD_shrinkstack(L1);
}


/*
** sweep at most 'count' elements from a list of GCObjects erasing dead
** objects, where a dead (not alive) object is one marked with the "old"
** (non current) white and not fixed.
** In non-generational mode, change all non-dead objects back to white,
** preparing for next collection cycle.
** In generational mode, keep black objects black, and also mark them as
** old; stop when hitting an old object, as all objects after that
** one will be old too.
** When object is a thread, sweep its list of open upvalues too.
*/
static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
  global_State *g = G(L);
  int ow = otherwhite(g);
  int toclear, toset;  /* bits to clear and to set in all live objects */
  int tostop;  /* stop sweep when this is true */
  if (isgenerational(g)) {  /* generational mode? */
    toclear = ~0;  /* clear nothing */
    toset = bitmask(OLDBIT);  /* set the old bit of all surviving objects */
    tostop = bitmask(OLDBIT);  /* do not sweep old generation */
  }
  else {  /* normal mode */
    toclear = maskcolors;  /* clear all color bits + old bit */
    toset = luaC_white(g);  /* make object white */
    tostop = 0;  /* do not stop */
  }
  while (*p != NULL && count-- > 0) {
    GCObject *curr = *p;
    int marked = gch(curr)->marked;
    if (isdeadm(ow, marked)) {  /* is 'curr' dead? */
      *p = gch(curr)->next;  /* remove 'curr' from list */
      freeobj(L, curr);  /* erase 'curr' */
    }
    else {
      if (testbits(marked, tostop))
        return NULL;  /* stop sweeping this list */
      if (gch(curr)->tt == LUA_TTHREAD)
        sweepthread(L, gco2th(curr));  /* sweep thread's upvalues */
      /* update marks */
      gch(curr)->marked = cast_byte((marked & toclear) | toset);
      p = &gch(curr)->next;  /* go to next element */
    }
  }
  return (*p == NULL) ? NULL : p;
}


/*
** sweep a list until a live object (or end of list)
*/
static GCObject **sweeptolive (lua_State *L, GCObject **p, int *n) {
  GCObject ** old = p;
  int i = 0;
  do {
    i++;
    p = sweeplist(L, p, 1);
  } while (p == old);
  if (n) *n += i;
  return p;
}

/* }====================================================== */


/*
** {======================================================
** Finalization
** =======================================================
*/

static void checkSizes (lua_State *L) {
  global_State *g = G(L);
  if (g->gckind != KGC_EMERGENCY) {  /* do not change sizes in emergency */
    int hs = g->strt.size / 2;  /* half the size of the string table */
    if (g->strt.nuse < cast(lu_int32, hs))  /* using less than that half? */
      luaS_resize(L, hs);  /* halve its size */
    luaZ_freebuffer(L, &g->buff);  /* free concatenation buffer */
  }
}


static GCObject *udata2finalize (global_State *g) {
  GCObject *o = g->tobefnz;  /* get first element */
  lua_assert(isfinalized(o));
  g->tobefnz = gch(o)->next;  /* remove it from 'tobefnz' list */
  gch(o)->next = g->allgc;  /* return it to 'allgc' list */
  g->allgc = o;
  resetbit(gch(o)->marked, SEPARATED);  /* mark that it is not in 'tobefnz' */
  lua_assert(!isold(o));  /* see MOVE OLD rule */
  if (!keepinvariantout(g))  /* not keeping invariant? */
    makewhite(g, o);  /* "sweep" object */
  return o;
}


static void dothecall (lua_State *L, void *ud) {
  UNUSED(ud);
  luaD_call(L, L->top - 2, 0, 0);
}


static void GCTM (lua_State *L, int propagateerrors) {
  global_State *g = G(L);
  const TValue *tm;
  TValue v;
  setgcovalue(L, &v, udata2finalize(g));
  tm = luaT_gettmbyobj(L, &v, TM_GC);
  if (tm != NULL && ttisfunction(tm)) {  /* is there a finalizer? */
    int status;
    lu_byte oldah = L->allowhook;
    int running  = g->gcrunning;
    L->allowhook = 0;  /* stop debug hooks during GC metamethod */
    g->gcrunning = 0;  /* avoid GC steps */
    setobj2s(L, L->top, tm);  /* push finalizer... */
    setobj2s(L, L->top + 1, &v);  /* ... and its argument */
    L->top += 2;  /* and (next line) call the finalizer */
    status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
    L->allowhook = oldah;  /* restore hooks */
    g->gcrunning = running;  /* restore state */
    if (status != LUA_OK && propagateerrors) {  /* error while running __gc? */
      if (status == LUA_ERRRUN) {  /* is there an error object? */
        const char *msg = (ttisstring(L->top - 1))
                            ? svalue(L->top - 1)
                            : "no message";
        luaO_pushfstring(L, "error in __gc metamethod (%s)", msg);
        status = LUA_ERRGCMM;  /* error in __gc metamethod */
      }
      luaD_throw(L, status);  /* re-throw error */
    }
  }
}


/*
** move all unreachable objects (or 'all' objects) that need
** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
*/
static void separatetobefnz (lua_State *L, int all) {
  global_State *g = G(L);
  GCObject **p = &g->finobj;
  GCObject *curr;
  GCObject **lastnext = &g->tobefnz;
  /* find last 'next' field in 'tobefnz' list (to add elements in its end) */
  while (*lastnext != NULL)
    lastnext = &gch(*lastnext)->next;
  while ((curr = *p) != NULL) {  /* traverse all finalizable objects */
    lua_assert(!isfinalized(curr));
    lua_assert(testbit(gch(curr)->marked, SEPARATED));
    if (!(iswhite(curr) || all))  /* not being collected? */
      p = &gch(curr)->next;  /* don't bother with it */
    else {
      l_setbit(gch(curr)->marked, FINALIZEDBIT); /* won't be finalized again */
      *p = gch(curr)->next;  /* remove 'curr' from 'finobj' list */
      gch(curr)->next = *lastnext;  /* link at the end of 'tobefnz' list */
      *lastnext = curr;
      lastnext = &gch(curr)->next;
    }
  }
}


/*
** if object 'o' has a finalizer, remove it from 'allgc' list (must
** search the list to find it) and link it in 'finobj' list.
*/
void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
  global_State *g = G(L);
  if (testbit(gch(o)->marked, SEPARATED) || /* obj. is already separated... */
      isfinalized(o) ||                           /* ... or is finalized... */
      gfasttm(g, mt, TM_GC) == NULL)                /* or has no finalizer? */
    return;  /* nothing to be done */
  else {  /* move 'o' to 'finobj' list */
    GCObject **p;
    GCheader *ho = gch(o);
    if (g->sweepgc == &ho->next) {  /* avoid removing current sweep object */
      lua_assert(issweepphase(g));
      g->sweepgc = sweeptolive(L, g->sweepgc, NULL);
    }
    /* search for pointer pointing to 'o' */
    for (p = &g->allgc; *p != o; p = &gch(*p)->next) { /* empty */ }
    *p = ho->next;  /* remove 'o' from root list */
    ho->next = g->finobj;  /* link it in list 'finobj' */
    g->finobj = o;
    l_setbit(ho->marked, SEPARATED);  /* mark it as such */
    if (!keepinvariantout(g))  /* not keeping invariant? */
      makewhite(g, o);  /* "sweep" object */
    else
      resetoldbit(o);  /* see MOVE OLD rule */
  }
}

/* }====================================================== */


/*
** {======================================================
** GC control
** =======================================================
*/


/*
** set a reasonable "time" to wait before starting a new GC cycle;
** cycle will start when memory use hits threshold
*/
static void setpause (global_State *g, l_mem estimate) {
  l_mem debt, threshold;
  estimate = estimate / PAUSEADJ;  /* adjust 'estimate' */
  threshold = (g->gcpause < MAX_LMEM / estimate)  /* overflow? */
            ? estimate * g->gcpause  /* no overflow */
            : MAX_LMEM;  /* overflow; truncate to maximum */
  debt = -cast(l_mem, threshold - gettotalbytes(g));
  luaE_setdebt(g, debt);
}


#define sweepphases  \
	(bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))


/*
** enter first sweep phase (strings) and prepare pointers for other
** sweep phases.  The calls to 'sweeptolive' make pointers point to an
** object inside the list (instead of to the header), so that the real
** sweep do not need to skip objects created between "now" and the start
** of the real sweep.
** Returns how many objects it swept.
*/
static int entersweep (lua_State *L) {
  global_State *g = G(L);
  int n = 0;
  g->gcstate = GCSsweepstring;
  lua_assert(g->sweepgc == NULL && g->sweepfin == NULL);
  /* prepare to sweep strings, finalizable objects, and regular objects */
  g->sweepstrgc = 0;
  g->sweepfin = sweeptolive(L, &g->finobj, &n);
  g->sweepgc = sweeptolive(L, &g->allgc, &n);
  return n;
}


/*
** change GC mode
*/
void luaC_changemode (lua_State *L, int mode) {
  global_State *g = G(L);
  if (mode == g->gckind) return;  /* nothing to change */
  if (mode == KGC_GEN) {  /* change to generational mode */
    /* make sure gray lists are consistent */
    luaC_runtilstate(L, bitmask(GCSpropagate));
    g->GCestimate = gettotalbytes(g);
    g->gckind = KGC_GEN;
  }
  else {  /* change to incremental mode */
    /* sweep all objects to turn them back to white
       (as white has not changed, nothing extra will be collected) */
    g->gckind = KGC_NORMAL;
    entersweep(L);
    luaC_runtilstate(L, ~sweepphases);
  }
}


/*
** call all pending finalizers
*/
static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
  global_State *g = G(L);
  while (g->tobefnz) {
    resetoldbit(g->tobefnz);
    GCTM(L, propagateerrors);
  }
}


void luaC_freeallobjects (lua_State *L) {
  global_State *g = G(L);
  int i;
  separatetobefnz(L, 1);  /* separate all objects with finalizers */
  lua_assert(g->finobj == NULL);
  callallpendingfinalizers(L, 0);
  g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
  g->gckind = KGC_NORMAL;
  sweepwholelist(L, &g->finobj);  /* finalizers can create objs. in 'finobj' */
  sweepwholelist(L, &g->allgc);
  for (i = 0; i < g->strt.size; i++)  /* free all string lists */
    sweepwholelist(L, &g->strt.hash[i]);
  lua_assert(g->strt.nuse == 0);
}


static l_mem atomic (lua_State *L) {
  global_State *g = G(L);
  l_mem work = -cast(l_mem, g->GCmemtrav);  /* start counting work */
  GCObject *origweak, *origall;
  lua_assert(!iswhite(obj2gco(g->mainthread)));
  markobject(g, L);  /* mark running thread */
  /* registry and global metatables may be changed by API */
  markvalue(g, &g->l_registry);
  markmt(g);  /* mark basic metatables */
  /* remark occasional upvalues of (maybe) dead threads */
  remarkupvals(g);
  propagateall(g);  /* propagate changes */
  work += g->GCmemtrav;  /* stop counting (do not (re)count grays) */
  /* traverse objects caught by write barrier and by 'remarkupvals' */
  retraversegrays(g);
  work -= g->GCmemtrav;  /* restart counting */
  convergeephemerons(g);
  /* at this point, all strongly accessible objects are marked. */
  /* clear values from weak tables, before checking finalizers */
  clearvalues(g, g->weak, NULL);
  clearvalues(g, g->allweak, NULL);
  origweak = g->weak; origall = g->allweak;
  work += g->GCmemtrav;  /* stop counting (objects being finalized) */
  separatetobefnz(L, 0);  /* separate objects to be finalized */
  markbeingfnz(g);  /* mark objects that will be finalized */
  propagateall(g);  /* remark, to propagate `preserveness' */
  work -= g->GCmemtrav;  /* restart counting */
  convergeephemerons(g);
  /* at this point, all resurrected objects are marked. */
  /* remove dead objects from weak tables */
  clearkeys(g, g->ephemeron, NULL);  /* clear keys from all ephemeron tables */
  clearkeys(g, g->allweak, NULL);  /* clear keys from all allweak tables */
  /* clear values from resurrected weak tables */
  clearvalues(g, g->weak, origweak);
  clearvalues(g, g->allweak, origall);
  g->currentwhite = cast_byte(otherwhite(g));  /* flip current white */
  work += g->GCmemtrav;  /* complete counting */
  return work;  /* estimate of memory marked by 'atomic' */
}


static lu_mem singlestep (lua_State *L) {
  global_State *g = G(L);
  switch (g->gcstate) {
    case GCSpause: {
      /* start to count memory traversed */
      g->GCmemtrav = g->strt.size * sizeof(GCObject*);
      lua_assert(!isgenerational(g));
      restartcollection(g);
      g->gcstate = GCSpropagate;
      return g->GCmemtrav;
    }
    case GCSpropagate: {
      if (g->gray) {
        lu_mem oldtrav = g->GCmemtrav;
        propagatemark(g);
        return g->GCmemtrav - oldtrav;  /* memory traversed in this step */
      }
      else {  /* no more `gray' objects */
        lu_mem work;
        int sw;
        g->gcstate = GCSatomic;  /* finish mark phase */
        g->GCestimate = g->GCmemtrav;  /* save what was counted */;
        work = atomic(L);  /* add what was traversed by 'atomic' */
        g->GCestimate += work;  /* estimate of total memory traversed */ 
        sw = entersweep(L);
        return work + sw * GCSWEEPCOST;
      }
    }
    case GCSsweepstring: {
      int i;
      for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
        sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
      g->sweepstrgc += i;
      if (g->sweepstrgc >= g->strt.size)  /* no more strings to sweep? */
        g->gcstate = GCSsweepudata;
      return i * GCSWEEPCOST;
    }
    case GCSsweepudata: {
      if (g->sweepfin) {
        g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
        return GCSWEEPMAX*GCSWEEPCOST;
      }
      else {
        g->gcstate = GCSsweep;
        return 0;
      }
    }
    case GCSsweep: {
      if (g->sweepgc) {
        g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
        return GCSWEEPMAX*GCSWEEPCOST;
      }
      else {
        /* sweep main thread */
        GCObject *mt = obj2gco(g->mainthread);
        sweeplist(L, &mt, 1);
        checkSizes(L);
        g->gcstate = GCSpause;  /* finish collection */
        return GCSWEEPCOST;
      }
    }
    default: lua_assert(0); return 0;
  }
}


/*
** advances the garbage collector until it reaches a state allowed
** by 'statemask'
*/
void luaC_runtilstate (lua_State *L, int statesmask) {
  global_State *g = G(L);
  while (!testbit(statesmask, g->gcstate))
    singlestep(L);
}


static void generationalcollection (lua_State *L) {
  global_State *g = G(L);
  lua_assert(g->gcstate == GCSpropagate);
  if (g->GCestimate == 0) {  /* signal for another major collection? */
    luaC_fullgc(L, 0);  /* perform a full regular collection */
    g->GCestimate = gettotalbytes(g);  /* update control */
  }
  else {
    lu_mem estimate = g->GCestimate;
    luaC_runtilstate(L, bitmask(GCSpause));  /* run complete (minor) cycle */
    g->gcstate = GCSpropagate;  /* skip restart */
    if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc)
      g->GCestimate = 0;  /* signal for a major collection */
    else
      g->GCestimate = estimate;  /* keep estimate from last major coll. */

  }
  setpause(g, gettotalbytes(g));
  lua_assert(g->gcstate == GCSpropagate);
}


static void incstep (lua_State *L) {
  global_State *g = G(L);
  l_mem debt = g->GCdebt;
  int stepmul = g->gcstepmul;
  if (stepmul < 40) stepmul = 40;  /* avoid ridiculous low values (and 0) */
  /* convert debt from Kb to 'work units' (avoid zero debt and overflows) */
  debt = (debt / STEPMULADJ) + 1;
  debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
  do {  /* always perform at least one single step */
    lu_mem work = singlestep(L);  /* do some work */
    debt -= work;
  } while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
  if (g->gcstate == GCSpause)
    setpause(g, g->GCestimate);  /* pause until next cycle */
  else {
    debt = (debt / stepmul) * STEPMULADJ;  /* convert 'work units' to Kb */
    luaE_setdebt(g, debt);
  }
}


/*
** performs a basic GC step
*/
void luaC_forcestep (lua_State *L) {
  global_State *g = G(L);
  int i;
  if (isgenerational(g)) generationalcollection(L);
  else incstep(L);
  /* run a few finalizers (or all of them at the end of a collect cycle) */
  for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
    GCTM(L, 1);  /* call one finalizer */
}


/*
** performs a basic GC step only if collector is running
*/
void luaC_step (lua_State *L) {
  global_State *g = G(L);
  if (g->gcrunning) luaC_forcestep(L);
  else luaE_setdebt(g, -GCSTEPSIZE);  /* avoid being called too often */
}



/*
** performs a full GC cycle; if "isemergency", does not call
** finalizers (which could change stack positions)
*/
void luaC_fullgc (lua_State *L, int isemergency) {
  global_State *g = G(L);
  int origkind = g->gckind;
  lua_assert(origkind != KGC_EMERGENCY);
  if (isemergency)  /* do not run finalizers during emergency GC */
    g->gckind = KGC_EMERGENCY;
  else {
    g->gckind = KGC_NORMAL;
    callallpendingfinalizers(L, 1);
  }
  if (keepinvariant(g)) {  /* may there be some black objects? */
    /* must sweep all objects to turn them back to white
       (as white has not changed, nothing will be collected) */
    entersweep(L);
  }
  /* finish any pending sweep phase to start a new cycle */
  luaC_runtilstate(L, bitmask(GCSpause));
  luaC_runtilstate(L, ~bitmask(GCSpause));  /* start new collection */
  luaC_runtilstate(L, bitmask(GCSpause));  /* run entire collection */
  if (origkind == KGC_GEN) {  /* generational mode? */
    /* generational mode must be kept in propagate phase */
    luaC_runtilstate(L, bitmask(GCSpropagate));
  }
  g->gckind = origkind;
  setpause(g, gettotalbytes(g));
  if (!isemergency)   /* do not run finalizers during emergency GC */
    callallpendingfinalizers(L, 1);
}

/* }====================================================== */