aboutsummaryrefslogtreecommitdiffstats
path: root/src/qmlcompiler/qqmljsbasicblocks.cpp
blob: 073e294f45601d758850f59d400ebe88a203723d (plain)
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
// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0

#include "qqmljsbasicblocks_p.h"

#include <QtQml/private/qv4instr_moth_p.h>

QT_BEGIN_NAMESPACE

using namespace Qt::Literals::StringLiterals;

DEFINE_BOOL_CONFIG_OPTION(qv4DumpBasicBlocks, QV4_DUMP_BASIC_BLOCKS)

void QQmlJSBasicBlocks::dumpBasicBlocks()
{
    qDebug().noquote() << "=== Basic Blocks for \"%1\""_L1.arg(m_context->name);
    for (const auto &[blockOffset, block] : m_basicBlocks) {
        QDebug debug = qDebug().nospace();
        debug << "Block " << blockOffset << ":\n";
        debug << "  jumpOrigins[" << block.jumpOrigins.size() << "]: ";
        for (auto origin : block.jumpOrigins) {
            debug << origin << ", ";
        }
        debug << "\n  readRegisters[" << block.readRegisters.size() << "]: ";
        for (auto reg : block.readRegisters) {
            debug << reg << ", ";
        }
        debug << "\n  readTypes[" << block.readTypes.size() << "]: ";
        for (const auto &type : block.readTypes) {
            debug << type->augmentedInternalName() << ", ";
        }
        debug << "\n  jumpTarget: " << block.jumpTarget;
        debug << "\n  jumpIsUnConditional: " << block.jumpIsUnconditional;
    }
    qDebug() << "\n";
}

void QQmlJSBasicBlocks::dumpDOTGraph()
{
    QString output;
    QTextStream s{ &output };
    s << "=== Basic Blocks Graph in DOT format for \"%1\" (spaces are encoded as"
         " &#160; to preserve formatting)\n"_L1.arg(m_context->name);
    s << "digraph BasicBlocks {\n"_L1;

    std::map<int, BasicBlock> blocks{ m_basicBlocks.begin(), m_basicBlocks.end() };
    for (const auto &[blockOffset, block] : blocks) {
        for (int originOffset : block.jumpOrigins) {
            int originBlockOffset;
            auto originBlockIt = blocks.find(originOffset);
            bool isBackEdge = false;
            if (originBlockIt != blocks.end()) {
                originBlockOffset = originOffset;
                isBackEdge = originOffset > blockOffset
                        && originBlockIt->second.jumpIsUnconditional;
            } else {
                originBlockOffset = std::prev(blocks.lower_bound(originOffset))->first;
            }
            s << "    %1 -> %2%3\n"_L1.arg(QString::number(originBlockOffset))
                            .arg(QString::number(blockOffset))
                            .arg(isBackEdge ? " [color=blue]"_L1 : ""_L1);
        }
    }

    for (const auto &[blockOffset, block] : blocks) {
        int beginOffset = std::max(0, blockOffset);
        auto nextBlockIt = blocks.lower_bound(blockOffset + 1);
        int nextBlockOffset = nextBlockIt == blocks.end() ? m_context->code.size() : nextBlockIt->first;
        QString dump = QV4::Moth::dumpBytecode(
                m_context->code.constData(), m_context->code.size(), m_context->locals.size(),
                m_context->formals->length(), beginOffset, nextBlockOffset - 1,
                m_context->lineAndStatementNumberMapping);
        dump = dump.replace(" "_L1, "&#160;"_L1); // prevent collapse of extra whitespace for formatting
        dump = dump.replace("\n"_L1, "\\l"_L1); // new line + left aligned
        s << "    %1 [shape=record, fontname=\"Monospace\", label=\"{Block %1: | %2}\"]\n"_L1
                        .arg(QString::number(blockOffset))
                        .arg(dump);
    }
    s << "}\n"_L1;

    // Have unique names to prevent overwriting of functions with the same name (eg. anonymous functions).
    static int functionCount = 0;
    static const auto dumpFolderPath = qEnvironmentVariable("QV4_DUMP_BASIC_BLOCKS");

    QString expressionName = m_context->name == ""_L1
            ? "anonymous"_L1
            : QString(m_context->name).replace(" "_L1, "_"_L1);
    QString fileName = "function"_L1 + QString::number(functionCount++) + "_"_L1 + expressionName + ".gv"_L1;
    QFile dumpFile(dumpFolderPath + (dumpFolderPath.endsWith("/"_L1) ? ""_L1 : "/"_L1) + fileName);

    if (dumpFolderPath == "-"_L1 || dumpFolderPath == "1"_L1 || dumpFolderPath == "true"_L1) {
        qDebug().noquote() << output;
    } else {
        if (!dumpFile.open(QIODeviceBase::Truncate | QIODevice::WriteOnly)) {
            qDebug() << "Error: Could not open file to dump the basic blocks into";
        } else {
            dumpFile.write(("//"_L1 + output).toLatin1().toStdString().c_str());
            dumpFile.close();
        }
    }
}

template<typename Container>
void deduplicate(Container &container)
{
    std::sort(container.begin(), container.end());
    auto erase = std::unique(container.begin(), container.end());
    container.erase(erase, container.end());
}

QQmlJSCompilePass::InstructionAnnotations QQmlJSBasicBlocks::run(
        const Function *function,
        const InstructionAnnotations &annotations,
        QQmlJS::DiagnosticMessage *error)
{
    m_function = function;
    m_annotations = annotations;
    m_error = error;

    for (int i = 0, end = function->argumentTypes.size(); i != end; ++i) {
        InstructionAnnotation annotation;
        annotation.changedRegisterIndex = FirstArgument + i;
        annotation.changedRegister = function->argumentTypes[i];
        m_annotations[-annotation.changedRegisterIndex] = annotation;
    }

    for (int i = 0, end = function->registerTypes.size(); i != end; ++i) {
        InstructionAnnotation annotation;
        annotation.changedRegisterIndex = firstRegisterIndex() + i;
        annotation.changedRegister = function->registerTypes[i];
        m_annotations[-annotation.changedRegisterIndex] = annotation;
    }

    m_basicBlocks.insert_or_assign(m_annotations.begin().key(), BasicBlock());

    const QByteArray byteCode = function->code;
    decode(byteCode.constData(), static_cast<uint>(byteCode.size()));
    if (m_hadBackJumps) {
        // We may have missed some connections between basic blocks if there were back jumps.
        // Fill them in via a second pass.

        // We also need to re-calculate the jump targets then because the basic block boundaries
        // may have shifted.
        for (auto it = m_basicBlocks.begin(), end = m_basicBlocks.end(); it != end; ++it) {
            it->second.jumpTarget = -1;
            it->second.jumpIsUnconditional = false;
        }

        m_skipUntilNextLabel = false;

        reset();
        decode(byteCode.constData(), static_cast<uint>(byteCode.size()));
        for (auto it = m_basicBlocks.begin(), end = m_basicBlocks.end(); it != end; ++it)
            deduplicate(it->second.jumpOrigins);
    }

    populateBasicBlocks();
    populateReaderLocations();
    adjustTypes();

    if (qv4DumpBasicBlocks()) {
        dumpBasicBlocks();
        dumpDOTGraph();
    }

    return std::move(m_annotations);
}

QV4::Moth::ByteCodeHandler::Verdict QQmlJSBasicBlocks::startInstruction(QV4::Moth::Instr::Type type)
{
    auto it = m_basicBlocks.find(currentInstructionOffset());
    if (it != m_basicBlocks.end()) {
        m_skipUntilNextLabel = false;
    } else if (m_skipUntilNextLabel && !instructionManipulatesContext(type)) {
        return SkipInstruction;
    }

    return ProcessInstruction;
}

void QQmlJSBasicBlocks::endInstruction(QV4::Moth::Instr::Type)
{
    if (m_skipUntilNextLabel)
        return;
    auto it = m_basicBlocks.find(nextInstructionOffset());
    if (it != m_basicBlocks.end())
        it->second.jumpOrigins.append(currentInstructionOffset());
}

void QQmlJSBasicBlocks::generate_Jump(int offset)
{
    processJump(offset, Unconditional);
}

void QQmlJSBasicBlocks::generate_JumpTrue(int offset)
{
    processJump(offset, Conditional);
}

void QQmlJSBasicBlocks::generate_JumpFalse(int offset)
{
    processJump(offset, Conditional);
}

void QQmlJSBasicBlocks::generate_JumpNoException(int offset)
{
    processJump(offset, Conditional);
}

void QQmlJSBasicBlocks::generate_JumpNotUndefined(int offset)
{
    processJump(offset, Conditional);
}

void QQmlJSBasicBlocks::generate_Ret()
{
    m_skipUntilNextLabel = true;
}

void QQmlJSBasicBlocks::generate_ThrowException()
{
    m_skipUntilNextLabel = true;
}

void QQmlJSBasicBlocks::generate_DefineArray(int argc, int argv)
{
    if (argc == 0)
        return; // empty array/list, nothing to do

    m_objectAndArrayDefinitions.append({
        currentInstructionOffset(), ObjectOrArrayDefinition::arrayClassId, argc, argv
    });
}

void QQmlJSBasicBlocks::generate_DefineObjectLiteral(int internalClassId, int argc, int argv)
{
    if (argc == 0)
        return;

    m_objectAndArrayDefinitions.append({ currentInstructionOffset(), internalClassId, argc, argv });
}

void QQmlJSBasicBlocks::processJump(int offset, JumpMode mode)
{
    if (offset < 0)
        m_hadBackJumps = true;
    const int jumpTarget = absoluteOffset(offset);
    Q_ASSERT(!m_basicBlocks.isEmpty());
    auto currentBlock = m_basicBlocks.lower_bound(currentInstructionOffset());
    if (currentBlock == m_basicBlocks.end() || currentBlock->first != currentInstructionOffset())
        --currentBlock;
    currentBlock->second.jumpTarget = jumpTarget;
    currentBlock->second.jumpIsUnconditional = (mode == Unconditional);
    m_basicBlocks[jumpTarget].jumpOrigins.append(currentInstructionOffset());
    if (mode == Unconditional)
        m_skipUntilNextLabel = true;
    else
        m_basicBlocks.insert(nextInstructionOffset(), BasicBlock());
}

template<typename ContainerA, typename ContainerB>
static bool containsAny(const ContainerA &container, const ContainerB &elements)
{
    for (const auto &element : elements) {
        if (container.contains(element))
            return true;
    }
    return false;
}

template<typename ContainerA, typename ContainerB>
static bool containsAll(const ContainerA &container, const ContainerB &elements)
{
    for (const auto &element : elements) {
        if (!container.contains(element))
            return false;
    }
    return true;
}

template<class Key, class T, class Compare = std::less<Key>,
         class KeyContainer = QList<Key>, class MappedContainer = QList<T>>
class NewFlatMap
{
public:
    using OriginalFlatMap = QFlatMap<Key, T, Compare, KeyContainer, MappedContainer>;

    void appendOrdered(const typename OriginalFlatMap::iterator &i) {
        keys.append(i.key());
        values.append(i.value());
    }

    OriginalFlatMap take() {
        OriginalFlatMap result(Qt::OrderedUniqueRange, std::move(keys), std::move(values));
        keys.clear();
        values.clear();
        return result;
    }

private:
    typename OriginalFlatMap::key_container_type keys;
    typename OriginalFlatMap::mapped_container_type values;
};

struct PendingBlock
{
    QList<int> conversions;
    int start = -1;
    bool registerActive = false;
};

void QQmlJSBasicBlocks::populateReaderLocations()
{
    using NewInstructionAnnotations = NewFlatMap<int, InstructionAnnotation>;

    bool erasedReaders = false;
    auto eraseDeadStore = [&](const InstructionAnnotations::iterator &it) {
        auto reader = m_readerLocations.find(it.key());
        if (reader != m_readerLocations.end()
                && (reader->typeReaders.isEmpty()
                    || reader->registerReadersAndConversions.isEmpty())) {

            if (it->second.isRename) {
                // If it's a rename, it doesn't "own" its output type. The type may
                // still be read elsewhere, even if this register isn't. However, we're
                // not interested in the variant or any other details of the register.
                // Therefore just delete it.
                it->second.changedRegisterIndex = InvalidRegister;
                it->second.changedRegister = QQmlJSRegisterContent();
            } else {
                // void the output, rather than deleting it. We still need its variant.
                bool adjusted = m_typeResolver->adjustTrackedType(
                            it->second.changedRegister.storedType(),
                            m_typeResolver->voidType());
                Q_ASSERT(adjusted); // Can always convert to void

                adjusted = m_typeResolver->adjustTrackedType(
                            m_typeResolver->containedType(it->second.changedRegister),
                            m_typeResolver->voidType());
                Q_ASSERT(adjusted); // Can always convert to void
            }
            m_readerLocations.erase(reader);

            // If it's not a label and has no side effects, we can drop the instruction.
            if (!it->second.hasSideEffects) {
                if (!it->second.readRegisters.isEmpty()) {
                    it->second.readRegisters.clear();
                    erasedReaders = true;
                }
                if (m_basicBlocks.find(it.key()) == m_basicBlocks.end())
                    return true;
            }
        }
        return false;
    };

    NewInstructionAnnotations newAnnotations;
    for (auto writeIt = m_annotations.begin(), writeEnd = m_annotations.end();
         writeIt != writeEnd; ++writeIt) {
        const int writtenRegister = writeIt->second.changedRegisterIndex;
        if (writtenRegister == InvalidRegister) {
            newAnnotations.appendOrdered(writeIt);
            continue;
        }

        RegisterAccess &access = m_readerLocations[writeIt.key()];
        access.trackedRegister = writtenRegister;
        if (writeIt->second.changedRegister.isConversion()) {
            // If it's a conversion, we have to check for all readers of the conversion origins.
            // This happens at jump targets where different types are merged. A StoreReg or similar
            // instruction must be optimized out if none of the types it can hold is read anymore.
            access.trackedTypes = writeIt->second.changedRegister.conversionOrigins();
        } else {
            access.trackedTypes.append(
                    m_typeResolver->trackedContainedType(writeIt->second.changedRegister));
        }

        auto blockIt = m_basicBlocks.lower_bound(writeIt.key());
        if (blockIt == m_basicBlocks.end() || blockIt->first != writeIt.key())
            --blockIt;

        QList<PendingBlock> blocks = { { {}, blockIt->first, true } };
        QHash<int, PendingBlock> processedBlocks;
        bool isFirstBlock = true;

        while (!blocks.isEmpty()) {
            const PendingBlock block = blocks.takeLast();

            // We can re-enter the first block from the beginning.
            // We will then find any reads before the write we're currently examining.
            if (!isFirstBlock)
                processedBlocks.insert(block.start, block);

            auto nextBlock = m_basicBlocks.find(block.start);
            auto currentBlock = nextBlock++;
            bool registerActive = block.registerActive;
            QList<int> conversions = block.conversions;

            const auto blockEnd = (nextBlock == m_basicBlocks.end())
                    ? m_annotations.end()
                    : m_annotations.find(nextBlock->first);

            auto blockInstr = isFirstBlock
                    ? (writeIt + 1)
                    : m_annotations.find(currentBlock->first);
            for (; blockInstr != blockEnd; ++blockInstr) {
                if (registerActive
                        && blockInstr->second.typeConversions.contains(writtenRegister)) {
                    conversions.append(blockInstr.key());
                }

                for (auto readIt = blockInstr->second.readRegisters.constBegin(),
                     end = blockInstr->second.readRegisters.constEnd();
                     readIt != end; ++readIt) {
                    if (!blockInstr->second.isRename && containsAny(
                                readIt->second.content.conversionOrigins(), access.trackedTypes)) {
                        Q_ASSERT(readIt->second.content.isConversion());
                        Q_ASSERT(readIt->second.content.conversionResult());
                        access.typeReaders[blockInstr.key()]
                                = readIt->second.content.conversionResult();
                    }
                    if (registerActive && readIt->first == writtenRegister)
                        access.registerReadersAndConversions[blockInstr.key()] = conversions;
                }

                if (blockInstr->second.changedRegisterIndex == writtenRegister) {
                    conversions.clear();
                    registerActive = false;
                }
            }

            auto scheduleBlock = [&](int blockStart) {
                // If we find that an already processed block has the register activated by this jump,
                // we need to re-evaluate it. We also need to propagate any newly found conversions.
                const auto processed = processedBlocks.find(blockStart);
                if (processed == processedBlocks.end())
                    blocks.append({conversions, blockStart, registerActive});
                else if (registerActive && !processed->registerActive)
                    blocks.append({conversions, blockStart, registerActive});
                else if (!containsAll(processed->conversions, conversions))
                    blocks.append({processed->conversions + conversions, blockStart, registerActive});
            };

            if (!currentBlock->second.jumpIsUnconditional && nextBlock != m_basicBlocks.end())
                scheduleBlock(nextBlock->first);

            const int jumpTarget = currentBlock->second.jumpTarget;
            if (jumpTarget != -1)
                scheduleBlock(jumpTarget);

            if (isFirstBlock)
                isFirstBlock = false;
        }

        if (!eraseDeadStore(writeIt))
            newAnnotations.appendOrdered(writeIt);
    }
    m_annotations = newAnnotations.take();

    while (erasedReaders) {
        erasedReaders = false;

        for (auto it = m_annotations.begin(), end = m_annotations.end(); it != end; ++it) {
            InstructionAnnotation &instruction = it->second;
            if (instruction.changedRegisterIndex < InvalidRegister) {
                newAnnotations.appendOrdered(it);
                continue;
            }

            auto readers = m_readerLocations.find(it.key());
            if (readers != m_readerLocations.end()) {
                for (auto typeIt = readers->typeReaders.begin();
                     typeIt != readers->typeReaders.end();) {
                    if (m_annotations.contains(typeIt.key()))
                        ++typeIt;
                    else
                        typeIt = readers->typeReaders.erase(typeIt);
                }

                for (auto registerIt = readers->registerReadersAndConversions.begin();
                     registerIt != readers->registerReadersAndConversions.end();) {
                    if (m_annotations.contains(registerIt.key()))
                        ++registerIt;
                    else
                        registerIt = readers->registerReadersAndConversions.erase(registerIt);
                }
            }

            if (!eraseDeadStore(it))
                newAnnotations.appendOrdered(it);
        }

        m_annotations = newAnnotations.take();
    }
}

bool QQmlJSBasicBlocks::canMove(int instructionOffset, const RegisterAccess &access) const
{
    if (access.registerReadersAndConversions.size() != 1)
        return false;
    const auto basicBlockForInstruction = [this](int instruction) {
        auto block = m_basicBlocks.lower_bound(instruction);
        if (block == m_basicBlocks.end() || block.key() == instruction)
            return block;
        Q_ASSERT(block.key() > instruction);
        if (block == m_basicBlocks.begin())
            return m_basicBlocks.end();
        return --block;
    };
    return basicBlockForInstruction(instructionOffset)
            == basicBlockForInstruction(access.registerReadersAndConversions.begin().key());
}

static QString adjustErrorMessage(
        const QQmlJSScope::ConstPtr &origin, const QQmlJSScope::ConstPtr &conversion) {
    return QLatin1String("Cannot convert from ")
            + origin->internalName() + QLatin1String(" to ") + conversion->internalName();
}

static QString adjustErrorMessage(
        const QQmlJSScope::ConstPtr &origin, const QList<QQmlJSScope::ConstPtr> &conversions) {
    if (conversions.size() == 1)
        return adjustErrorMessage(origin, conversions[0]);

    QString types;
    for (const QQmlJSScope::ConstPtr &type : conversions) {
        if (!types.isEmpty())
            types += QLatin1String(", ");
        types += type->internalName();
    }
    return QLatin1String("Cannot convert from ")
            + origin->internalName() + QLatin1String(" to union of ") + types;
}

void QQmlJSBasicBlocks::adjustTypes()
{
    using NewVirtualRegisters = NewFlatMap<int, VirtualRegister>;

    QHash<int, QList<int>> liveConversions;
    QHash<int, QList<int>> movableReads;

    const auto handleRegisterReadersAndConversions
            = [&](QHash<int, RegisterAccess>::const_iterator it) {
        for (auto conversions = it->registerReadersAndConversions.constBegin(),
             end = it->registerReadersAndConversions.constEnd(); conversions != end;
             ++conversions) {
            if (conversions->isEmpty() && canMove(it.key(), it.value()))
                movableReads[conversions.key()].append(it->trackedRegister);
            for (int conversion : *conversions)
                liveConversions[conversion].append(it->trackedRegister);
        }
    };

    const auto transformRegister = [&](const QQmlJSRegisterContent &content) {
        const QQmlJSScope::ConstPtr conversion
                = m_typeResolver->storedType(m_typeResolver->containedType(content));
        if (!m_typeResolver->adjustTrackedType(content.storedType(), conversion))
            setError(adjustErrorMessage(content.storedType(), conversion));
    };

    // Handle the array definitions first.
    // Changing the array type changes the expected element types.
    auto adjustArray = [&](int instructionOffset) {
        auto it = m_readerLocations.find(instructionOffset);
        if (it == m_readerLocations.end())
            return;

        const InstructionAnnotation &annotation = m_annotations[instructionOffset];

        Q_ASSERT(it->trackedTypes.size() == 1);
        Q_ASSERT(it->trackedTypes[0] == m_typeResolver->containedType(annotation.changedRegister));
        Q_ASSERT(!annotation.readRegisters.isEmpty());

        if (!m_typeResolver->adjustTrackedType(it->trackedTypes[0], it->typeReaders.values()))
            setError(adjustErrorMessage(it->trackedTypes[0], it->typeReaders.values()));

        // Now we don't adjust the type we store, but rather the type we expect to read. We
        // can do this because we've tracked the read type when we defined the array in
        // QQmlJSTypePropagator.
        if (QQmlJSScope::ConstPtr valueType = it->trackedTypes[0]->valueType()) {
            const QQmlJSRegisterContent content = annotation.readRegisters.begin().value().content;
            const QQmlJSScope::ConstPtr contained = m_typeResolver->containedType(content);
            if (!m_typeResolver->adjustTrackedType(contained, valueType))
                setError(adjustErrorMessage(contained, valueType));

            // We still need to adjust the stored type, too.
            transformRegister(content);
        }

        handleRegisterReadersAndConversions(it);
        m_readerLocations.erase(it);
    };

    // Handle the object definitions.
    // Changing the object type changes the expected property types.
    const auto adjustObject = [&](const ObjectOrArrayDefinition &object) {
        auto it = m_readerLocations.find(object.instructionOffset);
        if (it == m_readerLocations.end())
            return;

        const InstructionAnnotation &annotation = m_annotations[object.instructionOffset];

        Q_ASSERT(it->trackedTypes.size() == 1);
        Q_ASSERT(it->trackedTypes[0] == m_typeResolver->containedType(annotation.changedRegister));
        Q_ASSERT(!annotation.readRegisters.isEmpty());

        if (!m_typeResolver->adjustTrackedType(it->trackedTypes[0], it->typeReaders.values()))
            setError(adjustErrorMessage(it->trackedTypes[0], it->typeReaders.values()));

        QQmlJSScope::ConstPtr resultType = it->trackedTypes[0];

        const int classSize = m_jsUnitGenerator->jsClassSize(object.internalClassId);
        Q_ASSERT(object.argc >= classSize);

        for (int i = 0; i < classSize; ++i) {
            // Now we don't adjust the type we store, but rather the types we expect to read. We
            // can do this because we've tracked the read types when we defined the object in
            // QQmlJSTypePropagator.

            const QString propName = m_jsUnitGenerator->jsClassMember(object.internalClassId, i);
            const QQmlJSMetaProperty property = resultType->property(propName);
            if (!property.isValid()) {
                setError(
                        resultType->internalName()
                        + QLatin1String(" has no property called ")
                        + propName);
                continue;
            }
            const QQmlJSScope::ConstPtr propType = property.type();
            if (propType.isNull()) {
                setError(QLatin1String("Cannot resolve type of property ") + propName);
                continue;
            }
            const QQmlJSRegisterContent content = annotation.readRegisters[object.argv + i].content;
            const QQmlJSScope::ConstPtr contained = m_typeResolver->containedType(content);
            if (!m_typeResolver->adjustTrackedType(contained, propType))
                setError(adjustErrorMessage(contained, propType));

            // We still need to adjust the stored type, too.
            transformRegister(content);
        }

        // The others cannot be adjusted. We don't know their names, yet.
        // But we might still be able to use the variants.
    };

    // Iterate in reverse so that we can have nested lists and objects and the types are propagated
    // from the outer lists/objects to the inner ones.
    for (auto it = m_objectAndArrayDefinitions.crbegin(), end = m_objectAndArrayDefinitions.crend();
         it != end; ++it) {
        if (it->internalClassId != -1)
            adjustObject(*it);
        else
            adjustArray(it->instructionOffset);
    }

    for (auto it = m_readerLocations.begin(), end = m_readerLocations.end(); it != end; ++it) {
        handleRegisterReadersAndConversions(it);

        // There is always one first occurrence of any tracked type. Conversions don't change
        // the type.
        if (it->trackedTypes.size() != 1)
            continue;

        if (!m_typeResolver->adjustTrackedType(it->trackedTypes[0], it->typeReaders.values()))
            setError(adjustErrorMessage(it->trackedTypes[0], it->typeReaders.values()));
    }



    NewVirtualRegisters newRegisters;
    for (auto i = m_annotations.begin(), iEnd = m_annotations.end(); i != iEnd; ++i) {
        if (i->second.changedRegisterIndex != InvalidRegister)
            transformRegister(i->second.changedRegister);

        for (auto conversion = i->second.typeConversions.begin(),
             conversionEnd = i->second.typeConversions.end(); conversion != conversionEnd;
             ++conversion) {
            if (!liveConversions[i.key()].contains(conversion.key()))
                continue;

            QQmlJSScope::ConstPtr newResult;
            const auto content = conversion->second.content;
            if (content.isConversion()) {
                QQmlJSScope::ConstPtr conversionResult = content.conversionResult();
                const auto conversionOrigins = content.conversionOrigins();
                for (const auto &origin : conversionOrigins)
                    newResult = m_typeResolver->merge(newResult, origin);
                if (!m_typeResolver->adjustTrackedType(conversionResult, newResult))
                    setError(adjustErrorMessage(conversionResult, newResult));
            }
            transformRegister(content);
            newRegisters.appendOrdered(conversion);
        }
        i->second.typeConversions = newRegisters.take();

        for (int movable : std::as_const(movableReads[i.key()]))
            i->second.readRegisters[movable].canMove = true;
    }
}

void QQmlJSBasicBlocks::populateBasicBlocks()
{
    for (auto blockNext = m_basicBlocks.begin(), blockEnd = m_basicBlocks.end();
         blockNext != blockEnd;) {

        const auto blockIt = blockNext++;
        BasicBlock &block = blockIt->second;
        QList<QQmlJSScope::ConstPtr> writtenTypes;
        QList<int> writtenRegisters;

        const auto instrEnd = (blockNext == blockEnd)
                ? m_annotations.end()
                : m_annotations.find(blockNext->first);
        for (auto instrIt = m_annotations.find(blockIt->first); instrIt != instrEnd; ++instrIt) {
            const InstructionAnnotation &instruction = instrIt->second;
            for (auto it = instruction.readRegisters.begin(), end = instruction.readRegisters.end();
                 it != end; ++it) {
                if (!instruction.isRename) {
                    Q_ASSERT(it->second.content.isConversion());
                    for (const QQmlJSScope::ConstPtr &origin :
                         it->second.content.conversionOrigins()) {
                        if (!writtenTypes.contains(origin))
                            block.readTypes.append(origin);
                    }
                }
                if (!writtenRegisters.contains(it->first))
                    block.readRegisters.append(it->first);
            }

            // If it's just a renaming, the type has existed in a different register before.
            if (instruction.changedRegisterIndex != InvalidRegister) {
                if (!instruction.isRename) {
                    writtenTypes.append(m_typeResolver->trackedContainedType(
                                            instruction.changedRegister));
                }
                writtenRegisters.append(instruction.changedRegisterIndex);
            }
        }

        deduplicate(block.readTypes);
        deduplicate(block.readRegisters);
    }
}

QT_END_NAMESPACE