# -*- shell-script -*- # # Copyright by The HDF Group. # Copyright by the Board of Trustees of the University of Illinois. # All rights reserved. # # This file is part of HDF5. The full HDF5 copyright notice, including # terms governing use, modification, and redistribution, is contained in # the files COPYING and Copyright.html. COPYING can be found at the root # of the source code distribution tree; Copyright.html can be found at the # root level of an installed copy of the electronic HDF5 document set and # is linked from the top-level documents page. It can also be found at # http://hdfgroup.org/HDF5/doc/Copyright.html. If you do not have # access to either file, you may request a copy from help@hdfgroup.org. # This file is part of the HDF5 build script. It is processed shortly # after configure starts and defines, among other things, flags for # the various compile modes. #---------------------------------------------------------------------------- # Compiler flags. 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F9XSUFFIXFLAG="" FSEARCH_DIRS="" FCFLAGS="$FCFLAGS -dp -Wl-M405" DEBUG_FCFLAGS="" PROD_FCFLAGS="" PROFILE_FCFLAGS="" f9x_flags_set=yes fi a> 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 
/*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"
#include "Structure.h"

#include "Identifier.h"
#include "JSObject.h"
#include "PropertyNameArray.h"
#include "StructureChain.h"
#include "Lookup.h"
#include <wtf/RefCountedLeakCounter.h>
#include <wtf/RefPtr.h>

#if ENABLE(JSC_MULTIPLE_THREADS)
#include <wtf/Threading.h>
#endif

#define DUMP_STRUCTURE_ID_STATISTICS 0

#ifndef NDEBUG
#define DO_PROPERTYMAP_CONSTENCY_CHECK 0
#else
#define DO_PROPERTYMAP_CONSTENCY_CHECK 0
#endif

using namespace std;
using namespace WTF;

namespace JSC {

// Choose a number for the following so that most property maps are smaller,
// but it's not going to blow out the stack to allocate this number of pointers.
static const int smallMapThreshold = 1024;

// The point at which the function call overhead of the qsort implementation
// becomes small compared to the inefficiency of insertion sort.
static const unsigned tinyMapThreshold = 20;

static const unsigned newTableSize = 16;

#ifndef NDEBUG
static WTF::RefCountedLeakCounter structureCounter("Structure");

#if ENABLE(JSC_MULTIPLE_THREADS)
static Mutex& ignoreSetMutex = *(new Mutex);
#endif

static bool shouldIgnoreLeaks;
static HashSet<Structure*>& ignoreSet = *(new HashSet<Structure*>);
#endif

#if DUMP_STRUCTURE_ID_STATISTICS
static HashSet<Structure*>& liveStructureSet = *(new HashSet<Structure*>);
#endif

void Structure::dumpStatistics()
{
#if DUMP_STRUCTURE_ID_STATISTICS
    unsigned numberLeaf = 0;
    unsigned numberUsingSingleSlot = 0;
    unsigned numberSingletons = 0;
    unsigned numberWithPropertyMaps = 0;
    unsigned totalPropertyMapsSize = 0;

    HashSet<Structure*>::const_iterator end = liveStructureSet.end();
    for (HashSet<Structure*>::const_iterator it = liveStructureSet.begin(); it != end; ++it) {
        Structure* structure = *it;
        if (structure->m_usingSingleTransitionSlot) {
            if (!structure->m_transitions.singleTransition)
                ++numberLeaf;
            else
                ++numberUsingSingleSlot;

           if (!structure->m_previous && !structure->m_transitions.singleTransition)
                ++numberSingletons;
        }

        if (structure->m_propertyTable) {
            ++numberWithPropertyMaps;
            totalPropertyMapsSize += PropertyMapHashTable::allocationSize(structure->m_propertyTable->size);
            if (structure->m_propertyTable->deletedOffsets)
                totalPropertyMapsSize += (structure->m_propertyTable->deletedOffsets->capacity() * sizeof(unsigned)); 
        }
    }

    printf("Number of live Structures: %d\n", liveStructureSet.size());
    printf("Number of Structures using the single item optimization for transition map: %d\n", numberUsingSingleSlot);
    printf("Number of Structures that are leaf nodes: %d\n", numberLeaf);
    printf("Number of Structures that singletons: %d\n", numberSingletons);
    printf("Number of Structures with PropertyMaps: %d\n", numberWithPropertyMaps);

    printf("Size of a single Structures: %d\n", static_cast<unsigned>(sizeof(Structure)));
    printf("Size of sum of all property maps: %d\n", totalPropertyMapsSize);
    printf("Size of average of all property maps: %f\n", static_cast<double>(totalPropertyMapsSize) / static_cast<double>(liveStructureSet.size()));
#else
    printf("Dumping Structure statistics is not enabled.\n");
#endif
}

Structure::Structure(JSValue prototype, const TypeInfo& typeInfo)
    : m_typeInfo(typeInfo)
    , m_prototype(prototype)
    , m_specificValueInPrevious(0)
    , m_propertyTable(0)
    , m_propertyStorageCapacity(JSObject::inlineStorageCapacity)
    , m_offset(noOffset)
    , m_isDictionary(false)
    , m_isPinnedPropertyTable(false)
    , m_hasGetterSetterProperties(false)
    , m_usingSingleTransitionSlot(true)
    , m_attributesInPrevious(0)
{
    ASSERT(m_prototype);
    ASSERT(m_prototype.isObject() || m_prototype.isNull());

    m_transitions.singleTransition = 0;

#ifndef NDEBUG
#if ENABLE(JSC_MULTIPLE_THREADS)
    MutexLocker protect(ignoreSetMutex);
#endif
    if (shouldIgnoreLeaks)
        ignoreSet.add(this);
    else
        structureCounter.increment();
#endif

#if DUMP_STRUCTURE_ID_STATISTICS
    liveStructureSet.add(this);
#endif
}

Structure::~Structure()
{
    if (m_previous) {
        if (m_previous->m_usingSingleTransitionSlot) {
            m_previous->m_transitions.singleTransition = 0;
        } else {
            ASSERT(m_previous->m_transitions.table->contains(make_pair(m_nameInPrevious.get(), make_pair(m_attributesInPrevious, m_specificValueInPrevious))));
            m_previous->m_transitions.table->remove(make_pair(m_nameInPrevious.get(), make_pair(m_attributesInPrevious, m_specificValueInPrevious)));
        }
    }

    if (m_cachedPropertyNameArrayData)
        m_cachedPropertyNameArrayData->setCachedStructure(0);

    if (!m_usingSingleTransitionSlot)
        delete m_transitions.table;

    if (m_propertyTable) {
        unsigned entryCount = m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount;
        for (unsigned i = 1; i <= entryCount; i++) {
            if (UString::Rep* key = m_propertyTable->entries()[i].key)
                key->deref();
        }

        delete m_propertyTable->deletedOffsets;
        fastFree(m_propertyTable);
    }

#ifndef NDEBUG
#if ENABLE(JSC_MULTIPLE_THREADS)
    MutexLocker protect(ignoreSetMutex);
#endif
    HashSet<Structure*>::iterator it = ignoreSet.find(this);
    if (it != ignoreSet.end())
        ignoreSet.remove(it);
    else
        structureCounter.decrement();
#endif

#if DUMP_STRUCTURE_ID_STATISTICS
    liveStructureSet.remove(this);
#endif
}

void Structure::startIgnoringLeaks()
{
#ifndef NDEBUG
    shouldIgnoreLeaks = true;
#endif
}

void Structure::stopIgnoringLeaks()
{
#ifndef NDEBUG
    shouldIgnoreLeaks = false;
#endif
}

static bool isPowerOf2(unsigned v)
{
    // Taken from http://www.cs.utk.edu/~vose/c-stuff/bithacks.html
    
    return !(v & (v - 1)) && v;
}

static unsigned nextPowerOf2(unsigned v)
{
    // Taken from http://www.cs.utk.edu/~vose/c-stuff/bithacks.html
    // Devised by Sean Anderson, Sepember 14, 2001

    v--;
    v |= v >> 1;
    v |= v >> 2;
    v |= v >> 4;
    v |= v >> 8;
    v |= v >> 16;
    v++;

    return v;
}

static unsigned sizeForKeyCount(size_t keyCount)
{
    if (keyCount == notFound)
        return newTableSize;

    if (keyCount < 8)
        return newTableSize;

    if (isPowerOf2(keyCount))
        return keyCount * 4;

    return nextPowerOf2(keyCount) * 2;
}

void Structure::materializePropertyMap()
{
    ASSERT(!m_propertyTable);

    Vector<Structure*, 8> structures;
    structures.append(this);

    Structure* structure = this;

    // Search for the last Structure with a property table. 
    while ((structure = structure->previousID())) {
        if (structure->m_isPinnedPropertyTable) {
            ASSERT(structure->m_propertyTable);
            ASSERT(!structure->m_previous);

            m_propertyTable = structure->copyPropertyTable();
            break;
        }

        structures.append(structure);
    }

    if (!m_propertyTable)
        createPropertyMapHashTable(sizeForKeyCount(m_offset + 1));
    else {
        if (sizeForKeyCount(m_offset + 1) > m_propertyTable->size)
            rehashPropertyMapHashTable(sizeForKeyCount(m_offset + 1)); // This could be made more efficient by combining with the copy above. 
    }

    for (ptrdiff_t i = structures.size() - 2; i >= 0; --i) {
        structure = structures[i];
        structure->m_nameInPrevious->ref();
        PropertyMapEntry entry(structure->m_nameInPrevious.get(), structure->m_offset, structure->m_attributesInPrevious, structure->m_specificValueInPrevious, ++m_propertyTable->lastIndexUsed);
        insertIntoPropertyMapHashTable(entry);
    }
}

void Structure::getEnumerablePropertyNames(ExecState* exec, PropertyNameArray& propertyNames, JSObject* baseObject)
{
    bool shouldCache = propertyNames.shouldCache() && !(propertyNames.size() || m_isDictionary);

    if (shouldCache && m_cachedPropertyNameArrayData) {
        if (m_cachedPropertyNameArrayData->cachedPrototypeChain() == prototypeChain(exec)) {
            propertyNames.setData(m_cachedPropertyNameArrayData);
            return;
        }
        clearEnumerationCache();
    }

    getEnumerableNamesFromPropertyTable(propertyNames);
    getEnumerableNamesFromClassInfoTable(exec, baseObject->classInfo(), propertyNames);

    if (m_prototype.isObject()) {
        propertyNames.setShouldCache(false); // No need for our prototypes to waste memory on caching, since they're not being enumerated directly.
        asObject(m_prototype)->getPropertyNames(exec, propertyNames);
    }

    if (shouldCache) {
        m_cachedPropertyNameArrayData = propertyNames.data();
        m_cachedPropertyNameArrayData->setCachedPrototypeChain(prototypeChain(exec));
        m_cachedPropertyNameArrayData->setCachedStructure(this);
    }
}

void Structure::clearEnumerationCache()
{
    if (m_cachedPropertyNameArrayData)
        m_cachedPropertyNameArrayData->setCachedStructure(0);
    m_cachedPropertyNameArrayData.clear();
}

void Structure::growPropertyStorageCapacity()
{
    if (m_propertyStorageCapacity == JSObject::inlineStorageCapacity)
        m_propertyStorageCapacity = JSObject::nonInlineBaseStorageCapacity;
    else
        m_propertyStorageCapacity *= 2;
}

void Structure::despecifyDictionaryFunction(const Identifier& propertyName)
{
    const UString::Rep* rep = propertyName._ustring.rep();

    materializePropertyMapIfNecessary();

    ASSERT(m_isDictionary);
    ASSERT(m_propertyTable);

    unsigned i = rep->computedHash();

#if DUMP_PROPERTYMAP_STATS
    ++numProbes;
#endif

    unsigned entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
    ASSERT(entryIndex != emptyEntryIndex);

    if (rep == m_propertyTable->entries()[entryIndex - 1].key) {
        m_propertyTable->entries()[entryIndex - 1].specificValue = 0;
        return;
    }

#if DUMP_PROPERTYMAP_STATS
    ++numCollisions;
#endif

    unsigned k = 1 | doubleHash(rep->computedHash());

    while (1) {
        i += k;

#if DUMP_PROPERTYMAP_STATS
        ++numRehashes;
#endif

        entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
        ASSERT(entryIndex != emptyEntryIndex);

        if (rep == m_propertyTable->entries()[entryIndex - 1].key) {
            m_propertyTable->entries()[entryIndex - 1].specificValue = 0;
            return;
        }
    }
}

PassRefPtr<Structure> Structure::addPropertyTransitionToExistingStructure(Structure* structure, const Identifier& propertyName, unsigned attributes, JSCell* specificValue, size_t& offset)
{
    ASSERT(!structure->m_isDictionary);
    ASSERT(structure->typeInfo().type() == ObjectType);

    if (structure->m_usingSingleTransitionSlot) {
        Structure* existingTransition = structure->m_transitions.singleTransition;
        if (existingTransition && existingTransition->m_nameInPrevious.get() == propertyName.ustring().rep()
            && existingTransition->m_attributesInPrevious == attributes
            && existingTransition->m_specificValueInPrevious == specificValue) {

            ASSERT(structure->m_transitions.singleTransition->m_offset != noOffset);
            offset = structure->m_transitions.singleTransition->m_offset;
            return existingTransition;
        }
    } else {
        if (Structure* existingTransition = structure->m_transitions.table->get(make_pair(propertyName.ustring().rep(), make_pair(attributes, specificValue)))) {
            ASSERT(existingTransition->m_offset != noOffset);
            offset = existingTransition->m_offset;
            return existingTransition;
        }
    }

    return 0;
}

PassRefPtr<Structure> Structure::addPropertyTransition(Structure* structure, const Identifier& propertyName, unsigned attributes, JSCell* specificValue, size_t& offset)
{
    ASSERT(!structure->m_isDictionary);
    ASSERT(structure->typeInfo().type() == ObjectType);
    ASSERT(!Structure::addPropertyTransitionToExistingStructure(structure, propertyName, attributes, specificValue, offset));

    if (structure->transitionCount() > s_maxTransitionLength) {
        RefPtr<Structure> transition = toDictionaryTransition(structure);
        offset = transition->put(propertyName, attributes, specificValue);
        if (transition->propertyStorageSize() > transition->propertyStorageCapacity())
            transition->growPropertyStorageCapacity();
        return transition.release();
    }

    RefPtr<Structure> transition = create(structure->m_prototype, structure->typeInfo());

    transition->m_cachedPrototypeChain = structure->m_cachedPrototypeChain;
    transition->m_previous = structure;
    transition->m_nameInPrevious = propertyName.ustring().rep();
    transition->m_attributesInPrevious = attributes;
    transition->m_specificValueInPrevious = specificValue;
    transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
    transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;

    if (structure->m_propertyTable) {
        if (structure->m_isPinnedPropertyTable)
            transition->m_propertyTable = structure->copyPropertyTable();
        else {
            transition->m_propertyTable = structure->m_propertyTable;
            structure->m_propertyTable = 0;
        }
    } else {
        if (structure->m_previous)
            transition->materializePropertyMap();
        else
            transition->createPropertyMapHashTable();
    }

    offset = transition->put(propertyName, attributes, specificValue);
    if (transition->propertyStorageSize() > transition->propertyStorageCapacity())
        transition->growPropertyStorageCapacity();

    transition->m_offset = offset;

    if (structure->m_usingSingleTransitionSlot) {
        if (!structure->m_transitions.singleTransition) {
            structure->m_transitions.singleTransition = transition.get();
            return transition.release();
        }

        Structure* existingTransition = structure->m_transitions.singleTransition;
        structure->m_usingSingleTransitionSlot = false;
        StructureTransitionTable* transitionTable = new StructureTransitionTable;
        structure->m_transitions.table = transitionTable;
        transitionTable->add(make_pair(existingTransition->m_nameInPrevious.get(), make_pair(existingTransition->m_attributesInPrevious, existingTransition->m_specificValueInPrevious)), existingTransition);
    }
    structure->m_transitions.table->add(make_pair(propertyName.ustring().rep(), make_pair(attributes, specificValue)), transition.get());
    return transition.release();
}

PassRefPtr<Structure> Structure::removePropertyTransition(Structure* structure, const Identifier& propertyName, size_t& offset)
{
    ASSERT(!structure->m_isDictionary);

    RefPtr<Structure> transition = toDictionaryTransition(structure);

    offset = transition->remove(propertyName);

    return transition.release();
}

PassRefPtr<Structure> Structure::changePrototypeTransition(Structure* structure, JSValue prototype)
{
    RefPtr<Structure> transition = create(prototype, structure->typeInfo());

    transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
    transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;

    // Don't set m_offset, as one can not transition to this.

    structure->materializePropertyMapIfNecessary();
    transition->m_propertyTable = structure->copyPropertyTable();
    transition->m_isPinnedPropertyTable = true;

    return transition.release();
}

PassRefPtr<Structure> Structure::despecifyFunctionTransition(Structure* structure, const Identifier& replaceFunction)
{
    RefPtr<Structure> transition = create(structure->storedPrototype(), structure->typeInfo());

    transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
    transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;

    // Don't set m_offset, as one can not transition to this.

    structure->materializePropertyMapIfNecessary();
    transition->m_propertyTable = structure->copyPropertyTable();
    transition->m_isPinnedPropertyTable = true;

    bool removed = transition->despecifyFunction(replaceFunction);
    ASSERT_UNUSED(removed, removed);

    return transition.release();
}

PassRefPtr<Structure> Structure::getterSetterTransition(Structure* structure)
{
    RefPtr<Structure> transition = create(structure->storedPrototype(), structure->typeInfo());
    transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
    transition->m_hasGetterSetterProperties = transition->m_hasGetterSetterProperties;

    // Don't set m_offset, as one can not transition to this.

    structure->materializePropertyMapIfNecessary();
    transition->m_propertyTable = structure->copyPropertyTable();
    transition->m_isPinnedPropertyTable = true;

    return transition.release();
}

PassRefPtr<Structure> Structure::toDictionaryTransition(Structure* structure)
{
    ASSERT(!structure->m_isDictionary);

    RefPtr<Structure> transition = create(structure->m_prototype, structure->typeInfo());
    transition->m_isDictionary = true;
    transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
    transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;

    structure->materializePropertyMapIfNecessary();
    transition->m_propertyTable = structure->copyPropertyTable();
    transition->m_isPinnedPropertyTable = true;

    return transition.release();
}

PassRefPtr<Structure> Structure::fromDictionaryTransition(Structure* structure)
{
    ASSERT(structure->m_isDictionary);

    // Since dictionary Structures are not shared, and no opcodes specialize
    // for them, we don't need to allocate a new Structure when transitioning
    // to non-dictionary status.

    // FIMXE: We can make this more efficient by canonicalizing the Structure (draining the
    // deleted offsets vector) before transitioning from dictionary. 
    if (!structure->m_propertyTable || !structure->m_propertyTable->deletedOffsets || structure->m_propertyTable->deletedOffsets->isEmpty())
        structure->m_isDictionary = false;

    return structure;
}

size_t Structure::addPropertyWithoutTransition(const Identifier& propertyName, unsigned attributes, JSCell* specificValue)
{
    ASSERT(!m_transitions.singleTransition);

    materializePropertyMapIfNecessary();

    m_isPinnedPropertyTable = true;
    size_t offset = put(propertyName, attributes, specificValue);
    if (propertyStorageSize() > propertyStorageCapacity())
        growPropertyStorageCapacity();
    clearEnumerationCache();
    return offset;
}

size_t Structure::removePropertyWithoutTransition(const Identifier& propertyName)
{
    ASSERT(!m_transitions.singleTransition);
    ASSERT(m_isDictionary);

    materializePropertyMapIfNecessary();

    m_isPinnedPropertyTable = true;
    size_t offset = remove(propertyName);
    clearEnumerationCache();
    return offset;
}

#if DUMP_PROPERTYMAP_STATS

static int numProbes;
static int numCollisions;
static int numRehashes;
static int numRemoves;

struct PropertyMapStatisticsExitLogger {
    ~PropertyMapStatisticsExitLogger();
};

static PropertyMapStatisticsExitLogger logger;

PropertyMapStatisticsExitLogger::~PropertyMapStatisticsExitLogger()
{
    printf("\nJSC::PropertyMap statistics\n\n");
    printf("%d probes\n", numProbes);
    printf("%d collisions (%.1f%%)\n", numCollisions, 100.0 * numCollisions / numProbes);
    printf("%d rehashes\n", numRehashes);
    printf("%d removes\n", numRemoves);
}

#endif

static const unsigned deletedSentinelIndex = 1;

#if !DO_PROPERTYMAP_CONSTENCY_CHECK

inline void Structure::checkConsistency()
{
}

#endif

PropertyMapHashTable* Structure::copyPropertyTable()
{
    if (!m_propertyTable)
        return 0;

    size_t tableSize = PropertyMapHashTable::allocationSize(m_propertyTable->size);
    PropertyMapHashTable* newTable = static_cast<PropertyMapHashTable*>(fastMalloc(tableSize));
    memcpy(newTable, m_propertyTable, tableSize);

    unsigned entryCount = m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount;
    for (unsigned i = 1; i <= entryCount; ++i) {
        if (UString::Rep* key = newTable->entries()[i].key)
            key->ref();
    }

    // Copy the deletedOffsets vector.
    if (m_propertyTable->deletedOffsets)
        newTable->deletedOffsets = new Vector<unsigned>(*m_propertyTable->deletedOffsets);

    return newTable;
}

size_t Structure::get(const UString::Rep* rep, unsigned& attributes, JSCell*& specificValue)
{
    materializePropertyMapIfNecessary();
    if (!m_propertyTable)
        return notFound;

    unsigned i = rep->computedHash();

#if DUMP_PROPERTYMAP_STATS
    ++numProbes;
#endif

    unsigned entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
    if (entryIndex == emptyEntryIndex)
        return notFound;

    if (rep == m_propertyTable->entries()[entryIndex - 1].key) {
        attributes = m_propertyTable->entries()[entryIndex - 1].attributes;
        specificValue = m_propertyTable->entries()[entryIndex - 1].specificValue;
        return m_propertyTable->entries()[entryIndex - 1].offset;
    }

#if DUMP_PROPERTYMAP_STATS
    ++numCollisions;
#endif

    unsigned k = 1 | doubleHash(rep->computedHash());

    while (1) {
        i += k;

#if DUMP_PROPERTYMAP_STATS
        ++numRehashes;
#endif

        entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
        if (entryIndex == emptyEntryIndex)
            return notFound;

        if (rep == m_propertyTable->entries()[entryIndex - 1].key) {
            attributes = m_propertyTable->entries()[entryIndex - 1].attributes;
            specificValue = m_propertyTable->entries()[entryIndex - 1].specificValue;
            return m_propertyTable->entries()[entryIndex - 1].offset;
        }
    }
}

bool Structure::despecifyFunction(const Identifier& propertyName)
{
    ASSERT(!propertyName.isNull());

    materializePropertyMapIfNecessary();
    if (!m_propertyTable)
        return false;

    UString::Rep* rep = propertyName._ustring.rep();

    unsigned i = rep->computedHash();

#if DUMP_PROPERTYMAP_STATS
    ++numProbes;
#endif

    unsigned entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
    if (entryIndex == emptyEntryIndex)
        return false;

    if (rep == m_propertyTable->entries()[entryIndex - 1].key) {
        ASSERT(m_propertyTable->entries()[entryIndex - 1].specificValue);
        m_propertyTable->entries()[entryIndex - 1].specificValue = 0;
        return true;
    }

#if DUMP_PROPERTYMAP_STATS
    ++numCollisions;
#endif

    unsigned k = 1 | doubleHash(rep->computedHash());

    while (1) {
        i += k;

#if DUMP_PROPERTYMAP_STATS
        ++numRehashes;
#endif

        entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
        if (entryIndex == emptyEntryIndex)
            return false;

        if (rep == m_propertyTable->entries()[entryIndex - 1].key) {
            ASSERT(m_propertyTable->entries()[entryIndex - 1].specificValue);
            m_propertyTable->entries()[entryIndex - 1].specificValue = 0;
            return true;
        }
    }
}

size_t Structure::put(const Identifier& propertyName, unsigned attributes, JSCell* specificValue)
{
    ASSERT(!propertyName.isNull());
    ASSERT(get(propertyName) == notFound);

    checkConsistency();

    UString::Rep* rep = propertyName._ustring.rep();

    if (!m_propertyTable)
        createPropertyMapHashTable();

    // FIXME: Consider a fast case for tables with no deleted sentinels.

    unsigned i = rep->computedHash();
    unsigned k = 0;
    bool foundDeletedElement = false;
    unsigned deletedElementIndex = 0; // initialize to make the compiler happy

#if DUMP_PROPERTYMAP_STATS
    ++numProbes;
#endif

    while (1) {
        unsigned entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
        if (entryIndex == emptyEntryIndex)
            break;

        if (entryIndex == deletedSentinelIndex) {
            // If we find a deleted-element sentinel, remember it for use later.
            if (!foundDeletedElement) {
                foundDeletedElement = true;
                deletedElementIndex = i;
            }
        }

        if (k == 0) {
            k = 1 | doubleHash(rep->computedHash());
#if DUMP_PROPERTYMAP_STATS
            ++numCollisions;
#endif
        }

        i += k;

#if DUMP_PROPERTYMAP_STATS
        ++numRehashes;
#endif
    }

    // Figure out which entry to use.
    unsigned entryIndex = m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount + 2;
    if (foundDeletedElement) {
        i = deletedElementIndex;
        --m_propertyTable->deletedSentinelCount;

        // Since we're not making the table bigger, we can't use the entry one past
        // the end that we were planning on using, so search backwards for the empty
        // slot that we can use. We know it will be there because we did at least one
        // deletion in the past that left an entry empty.
        while (m_propertyTable->entries()[--entryIndex - 1].key) { }
    }

    // Create a new hash table entry.
    m_propertyTable->entryIndices[i & m_propertyTable->sizeMask] = entryIndex;

    // Create a new hash table entry.
    rep->ref();
    m_propertyTable->entries()[entryIndex - 1].key = rep;
    m_propertyTable->entries()[entryIndex - 1].attributes = attributes;
    m_propertyTable->entries()[entryIndex - 1].specificValue = specificValue;
    m_propertyTable->entries()[entryIndex - 1].index = ++m_propertyTable->lastIndexUsed;

    unsigned newOffset;
    if (m_propertyTable->deletedOffsets && !m_propertyTable->deletedOffsets->isEmpty()) {
        newOffset = m_propertyTable->deletedOffsets->last();
        m_propertyTable->deletedOffsets->removeLast();
    } else
        newOffset = m_propertyTable->keyCount;
    m_propertyTable->entries()[entryIndex - 1].offset = newOffset;

    ++m_propertyTable->keyCount;

    if ((m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount) * 2 >= m_propertyTable->size)
        expandPropertyMapHashTable();

    checkConsistency();
    return newOffset;
}

size_t Structure::remove(const Identifier& propertyName)
{
    ASSERT(!propertyName.isNull());

    checkConsistency();

    UString::Rep* rep = propertyName._ustring.rep();

    if (!m_propertyTable)
        return notFound;

#if DUMP_PROPERTYMAP_STATS
    ++numProbes;
    ++numRemoves;
#endif

    // Find the thing to remove.
    unsigned i = rep->computedHash();
    unsigned k = 0;
    unsigned entryIndex;
    UString::Rep* key = 0;
    while (1) {
        entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
        if (entryIndex == emptyEntryIndex)
            return notFound;

        key = m_propertyTable->entries()[entryIndex - 1].key;
        if (rep == key)
            break;

        if (k == 0) {
            k = 1 | doubleHash(rep->computedHash());
#if DUMP_PROPERTYMAP_STATS
            ++numCollisions;
#endif
        }

        i += k;

#if DUMP_PROPERTYMAP_STATS
        ++numRehashes;
#endif
    }

    // Replace this one element with the deleted sentinel. Also clear out
    // the entry so we can iterate all the entries as needed.
    m_propertyTable->entryIndices[i & m_propertyTable->sizeMask] = deletedSentinelIndex;

    size_t offset = m_propertyTable->entries()[entryIndex - 1].offset;

    key->deref();
    m_propertyTable->entries()[entryIndex - 1].key = 0;
    m_propertyTable->entries()[entryIndex - 1].attributes = 0;
    m_propertyTable->entries()[entryIndex - 1].specificValue = 0;
    m_propertyTable->entries()[entryIndex - 1].offset = 0;

    if (!m_propertyTable->deletedOffsets)
        m_propertyTable->deletedOffsets = new Vector<unsigned>;
    m_propertyTable->deletedOffsets->append(offset);

    ASSERT(m_propertyTable->keyCount >= 1);
    --m_propertyTable->keyCount;
    ++m_propertyTable->deletedSentinelCount;

    if (m_propertyTable->deletedSentinelCount * 4 >= m_propertyTable->size)
        rehashPropertyMapHashTable();

    checkConsistency();
    return offset;
}

void Structure::insertIntoPropertyMapHashTable(const PropertyMapEntry& entry)
{
    ASSERT(m_propertyTable);

    unsigned i = entry.key->computedHash();
    unsigned k = 0;

#if DUMP_PROPERTYMAP_STATS
    ++numProbes;
#endif

    while (1) {
        unsigned entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
        if (entryIndex == emptyEntryIndex)
            break;

        if (k == 0) {
            k = 1 | doubleHash(entry.key->computedHash());
#if DUMP_PROPERTYMAP_STATS
            ++numCollisions;
#endif
        }

        i += k;

#if DUMP_PROPERTYMAP_STATS
        ++numRehashes;
#endif
    }

    unsigned entryIndex = m_propertyTable->keyCount + 2;
    m_propertyTable->entryIndices[i & m_propertyTable->sizeMask] = entryIndex;
    m_propertyTable->entries()[entryIndex - 1] = entry;

    ++m_propertyTable->keyCount;
}

void Structure::createPropertyMapHashTable()
{
    ASSERT(sizeForKeyCount(7) == newTableSize);
    createPropertyMapHashTable(newTableSize);
}

void Structure::createPropertyMapHashTable(unsigned newTableSize)
{
    ASSERT(!m_propertyTable);
    ASSERT(isPowerOf2(newTableSize));

    checkConsistency();

    m_propertyTable = static_cast<PropertyMapHashTable*>(fastZeroedMalloc(PropertyMapHashTable::allocationSize(newTableSize)));
    m_propertyTable->size = newTableSize;
    m_propertyTable->sizeMask = newTableSize - 1;

    checkConsistency();
}

void Structure::expandPropertyMapHashTable()
{
    ASSERT(m_propertyTable);
    rehashPropertyMapHashTable(m_propertyTable->size * 2);
}

void Structure::rehashPropertyMapHashTable()
{
    ASSERT(m_propertyTable);
    ASSERT(m_propertyTable->size);
    rehashPropertyMapHashTable(m_propertyTable->size);
}

void Structure::rehashPropertyMapHashTable(unsigned newTableSize)
{
    ASSERT(m_propertyTable);
    ASSERT(isPowerOf2(newTableSize));

    checkConsistency();

    PropertyMapHashTable* oldTable = m_propertyTable;

    m_propertyTable = static_cast<PropertyMapHashTable*>(fastZeroedMalloc(PropertyMapHashTable::allocationSize(newTableSize)));
    m_propertyTable->size = newTableSize;
    m_propertyTable->sizeMask = newTableSize - 1;

    unsigned lastIndexUsed = 0;
    unsigned entryCount = oldTable->keyCount + oldTable->deletedSentinelCount;
    for (unsigned i = 1; i <= entryCount; ++i) {
        if (oldTable->entries()[i].key) {
            lastIndexUsed = max(oldTable->entries()[i].index, lastIndexUsed);
            insertIntoPropertyMapHashTable(oldTable->entries()[i]);
        }
    }
    m_propertyTable->lastIndexUsed = lastIndexUsed;
    m_propertyTable->deletedOffsets = oldTable->deletedOffsets;

    fastFree(oldTable);

    checkConsistency();
}

static int comparePropertyMapEntryIndices(const void* a, const void* b)
{
    unsigned ia = static_cast<PropertyMapEntry* const*>(a)[0]->index;
    unsigned ib = static_cast<PropertyMapEntry* const*>(b)[0]->index;
    if (ia < ib)
        return -1;
    if (ia > ib)
        return +1;
    return 0;
}

void Structure::getEnumerableNamesFromPropertyTable(PropertyNameArray& propertyNames)
{
    materializePropertyMapIfNecessary();
    if (!m_propertyTable)
        return;

    if (m_propertyTable->keyCount < tinyMapThreshold) {
        PropertyMapEntry* a[tinyMapThreshold];
        int i = 0;
        unsigned entryCount = m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount;
        for (unsigned k = 1; k <= entryCount; k++) {
            if (m_propertyTable->entries()[k].key && !(m_propertyTable->entries()[k].attributes & DontEnum)) {
                PropertyMapEntry* value = &m_propertyTable->entries()[k];
                int j;
                for (j = i - 1; j >= 0 && a[j]->index > value->index; --j)
                    a[j + 1] = a[j];
                a[j + 1] = value;
                ++i;
            }
        }
        if (!propertyNames.size()) {
            for (int k = 0; k < i; ++k)
                propertyNames.addKnownUnique(a[k]->key);
        } else {
            for (int k = 0; k < i; ++k)
                propertyNames.add(a[k]->key);
        }

        return;
    }

    // Allocate a buffer to use to sort the keys.
    Vector<PropertyMapEntry*, smallMapThreshold> sortedEnumerables(m_propertyTable->keyCount);

    // Get pointers to the enumerable entries in the buffer.
    PropertyMapEntry** p = sortedEnumerables.data();
    unsigned entryCount = m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount;
    for (unsigned i = 1; i <= entryCount; i++) {
        if (m_propertyTable->entries()[i].key && !(m_propertyTable->entries()[i].attributes & DontEnum))
            *p++ = &m_propertyTable->entries()[i];
    }

    size_t enumerableCount = p - sortedEnumerables.data();
    // Sort the entries by index.
    qsort(sortedEnumerables.data(), enumerableCount, sizeof(PropertyMapEntry*), comparePropertyMapEntryIndices);
    sortedEnumerables.resize(enumerableCount);

    // Put the keys of the sorted entries into the list.
    if (!propertyNames.size()) {
        for (size_t i = 0; i < sortedEnumerables.size(); ++i)
            propertyNames.addKnownUnique(sortedEnumerables[i]->key);
    } else {
        for (size_t i = 0; i < sortedEnumerables.size(); ++i)
            propertyNames.add(sortedEnumerables[i]->key);
    }
}

void Structure::getEnumerableNamesFromClassInfoTable(ExecState* exec, const ClassInfo* classInfo, PropertyNameArray& propertyNames)
{
    // Add properties from the static hashtables of properties
    for (; classInfo; classInfo = classInfo->parentClass) {
        const HashTable* table = classInfo->propHashTable(exec);
        if (!table)
            continue;
        table->initializeIfNeeded(exec);
        ASSERT(table->table);

        int hashSizeMask = table->compactSize - 1;
        const HashEntry* entry = table->table;
        for (int i = 0; i <= hashSizeMask; ++i, ++entry) {
            if (entry->key() && !(entry->attributes() & DontEnum))
                propertyNames.add(entry->key());
        }
    }
}

#if DO_PROPERTYMAP_CONSTENCY_CHECK

void Structure::checkConsistency()
{
    if (!m_propertyTable)
        return;

    ASSERT(m_propertyTable->size >= newTableSize);
    ASSERT(m_propertyTable->sizeMask);
    ASSERT(m_propertyTable->size == m_propertyTable->sizeMask + 1);
    ASSERT(!(m_propertyTable->size & m_propertyTable->sizeMask));

    ASSERT(m_propertyTable->keyCount <= m_propertyTable->size / 2);
    ASSERT(m_propertyTable->deletedSentinelCount <= m_propertyTable->size / 4);

    ASSERT(m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount <= m_propertyTable->size / 2);

    unsigned indexCount = 0;
    unsigned deletedIndexCount = 0;
    for (unsigned a = 0; a != m_propertyTable->size; ++a) {
        unsigned entryIndex = m_propertyTable->entryIndices[a];
        if (entryIndex == emptyEntryIndex)
            continue;
        if (entryIndex == deletedSentinelIndex) {
            ++deletedIndexCount;
            continue;
        }
        ASSERT(entryIndex > deletedSentinelIndex);
        ASSERT(entryIndex - 1 <= m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount);
        ++indexCount;

        for (unsigned b = a + 1; b != m_propertyTable->size; ++b)
            ASSERT(m_propertyTable->entryIndices[b] != entryIndex);
    }
    ASSERT(indexCount == m_propertyTable->keyCount);
    ASSERT(deletedIndexCount == m_propertyTable->deletedSentinelCount);

    ASSERT(m_propertyTable->entries()[0].key == 0);

    unsigned nonEmptyEntryCount = 0;
    for (unsigned c = 1; c <= m_propertyTable->keyCount + m_propertyTable->deletedSentinelCount; ++c) {
        UString::Rep* rep = m_propertyTable->entries()[c].key;
        if (!rep)
            continue;
        ++nonEmptyEntryCount;
        unsigned i = rep->computedHash();
        unsigned k = 0;
        unsigned entryIndex;
        while (1) {
            entryIndex = m_propertyTable->entryIndices[i & m_propertyTable->sizeMask];
            ASSERT(entryIndex != emptyEntryIndex);
            if (rep == m_propertyTable->entries()[entryIndex - 1].key)
                break;
            if (k == 0)
                k = 1 | doubleHash(rep->computedHash());
            i += k;
        }
        ASSERT(entryIndex == c + 1);
    }

    ASSERT(nonEmptyEntryCount == m_propertyTable->keyCount);
}

#endif // DO_PROPERTYMAP_CONSTENCY_CHECK

} // namespace JSC
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