Move line number information into a side table

Don't emit any Line instructions anymore, and instead store
the info in a side table in the compiled data, where it can
be looked up on demand.

Change-Id: Idcaf3bf4ee4129fd62f9e717bf1277dc6a34fe19
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>

8 files changed, 60 insertions, 35 deletions

diff --git a/src/qml/compiler/qv4bytecodegenerator.cpp b/src/qml/compiler/qv4bytecodegenerator.cpp
index c9b7c4ae7e..cae984a253 100644
--- a/src/qml/compiler/qv4bytecodegenerator.cpp
+++ b/src/qml/compiler/qv4bytecodegenerator.cpp
@@ -38,6 +38,7 @@
 ****************************************************************************/
 
 #include <private/qv4bytecodegenerator_p.h>
+#include <private/qv4compilercontext_p.h>
 #include <private/qqmljsastfwd_p.h>
 
 QT_USE_NAMESPACE
@@ -46,12 +47,7 @@ using namespace Moth;
 
 void BytecodeGenerator::setLocation(const QQmlJS::AST::SourceLocation &loc)
 {
-    if (static_cast<int>(loc.startLine) == currentLine)
-        return;
     currentLine = static_cast<int>(loc.startLine);
-    Instruction::Line line;
-    line.lineNumber = currentLine;
-    addInstruction(line); //### put line numbers in a side-table, not in the instruction stream
 }
 
 int BytecodeGenerator::newRegister()
@@ -71,14 +67,23 @@ int BytecodeGenerator::newRegisterArray(int n)
     return t;
 }
 
-QByteArray BytecodeGenerator::finalize()
+void BytecodeGenerator::finalize(Compiler::Context *context)
 {
     QByteArray code;
 
     // content
     QVector<int> instructionOffsets;
+    QVector<int> lineNumbers;
+    currentLine = startLine;
     instructionOffsets.reserve(instructions.size());
     for (const auto &i : qAsConst(instructions)) {
+        if (i.line != currentLine) {
+            Q_ASSERT(i.line > currentLine);
+            while (currentLine < i.line) {
+                lineNumbers.append(code.size());
+                ++currentLine;
+            }
+        }
         instructionOffsets.append(code.size());
         code.append(reinterpret_cast<const char *>(&i.instr), i.size);
     }
@@ -97,5 +102,6 @@ QByteArray BytecodeGenerator::finalize()
         memcpy(c, &linkedInstructionOffset, sizeof(ptrdiff_t));
     }
 
-    return code;
+    context->code = code;
+    context->lineNumberMapping = lineNumbers;
 }
diff --git a/src/qml/compiler/qv4bytecodegenerator_p.h b/src/qml/compiler/qv4bytecodegenerator_p.h
index f53a720d2c..5ab8c880f3 100644
--- a/src/qml/compiler/qv4bytecodegenerator_p.h
+++ b/src/qml/compiler/qv4bytecodegenerator_p.h
@@ -65,6 +65,8 @@ namespace Moth {
 
 class BytecodeGenerator {
 public:
+    BytecodeGenerator(int line)
+        : startLine(line) {}
 
     struct Label {
         enum LinkMode {
@@ -221,7 +223,7 @@ public:
     int newRegisterArray(int n);
     int registerCount() const { return regCount; }
 
-    QByteArray finalize();
+    void finalize(Compiler::Context *context);
 
     template<int InstrT>
     Jump addJumpInstruction(const InstrData<InstrT> &data)
@@ -239,7 +241,7 @@ private:
 
     int addInstructionHelper(uint size, const Instr &i) {
         int pos = instructions.size();
-        instructions.append({size, i});
+        instructions.append({size, currentLine, i});
         return pos;
     }
 
@@ -251,6 +253,7 @@ private:
 
     struct I {
         uint size;
+        int line;
         Instr instr;
     };
 
@@ -262,7 +265,8 @@ private:
 public:
     int currentReg = 0;
 private:
-    int currentLine = -1;
+    int startLine = 0;
+    int currentLine = 0;
 };
 
 }
diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 273856e541..7e8a823939 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -1932,7 +1932,7 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
     // ### still needed?
     _context->maxNumberOfArguments = qMax(_context->maxNumberOfArguments, (int)QV4::Global::ReservedArgumentCount);
 
-    BytecodeGenerator bytecode;
+    BytecodeGenerator bytecode(_context->line);
     BytecodeGenerator *savedBytecodeGenerator;
     savedBytecodeGenerator = bytecodeGenerator;
     bytecodeGenerator = &bytecode;
@@ -2025,13 +2025,14 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
         bytecodeGenerator->addInstruction(Instruction::Ret());
     }
 
-    _context->code = bytecodeGenerator->finalize();
+    bytecodeGenerator->finalize(_context);
     _context->registerCount = bytecodeGenerator->registerCount();
     static const bool showCode = qEnvironmentVariableIsSet("QV4_SHOW_BYTECODE");
     if (showCode) {
         qDebug() << "=== Bytecode for" << _context->name << "strict mode" << _context->isStrict
                  << "register count" << _context->registerCount;
-        QV4::Moth::dumpBytecode(_context->code, _context->locals.size(), _context->arguments.size());
+        QV4::Moth::dumpBytecode(_context->code, _context->locals.size(), _context->arguments.size(),
+                                _context->line, _context->lineNumberMapping);
         qDebug();
     }
 
diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index 91ef2eac20..445c3c7091 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -71,7 +71,7 @@
 QT_BEGIN_NAMESPACE
 
 // Bump this whenever the compiler data structures change in an incompatible way.
-#define QV4_DATA_STRUCTURE_VERSION 0x12
+#define QV4_DATA_STRUCTURE_VERSION 0x13
 
 class QIODevice;
 class QQmlPropertyCache;
@@ -217,6 +217,8 @@ struct Function
     quint32_le formalsOffset;
     quint32_le nLocals;
     quint32_le localsOffset;
+    quint32_le nLineNumbers;
+    quint32_le lineNumberOffset;
     quint32_le nInnerFunctions;
     quint32_le nRegisters;
     Location location;
@@ -240,6 +242,7 @@ struct Function
 
     const quint32_le *formalsTable() const { return reinterpret_cast<const quint32_le *>(reinterpret_cast<const char *>(this) + formalsOffset); }
     const quint32_le *localsTable() const { return reinterpret_cast<const quint32_le *>(reinterpret_cast<const char *>(this) + localsOffset); }
+    const quint32_le *lineNumberTable() const { return reinterpret_cast<const quint32_le *>(reinterpret_cast<const char *>(this) + lineNumberOffset); }
     const quint32_le *qmlIdObjectDependencyTable() const { return reinterpret_cast<const quint32_le *>(reinterpret_cast<const char *>(this) + dependingIdObjectsOffset); }
     const quint32_le *qmlContextPropertiesDependencyTable() const { return reinterpret_cast<const quint32_le *>(reinterpret_cast<const char *>(this) + dependingContextPropertiesOffset); }
     const quint32_le *qmlScopePropertiesDependencyTable() const { return reinterpret_cast<const quint32_le *>(reinterpret_cast<const char *>(this) + dependingScopePropertiesOffset); }
@@ -251,8 +254,8 @@ struct Function
 
     inline bool hasQmlDependencies() const { return nDependingIdObjects > 0 || nDependingContextProperties > 0 || nDependingScopeProperties > 0; }
 
-    static int calculateSize(int nFormals, int nLocals, int nInnerfunctions, int nIdObjectDependencies, int nPropertyDependencies) {
-        int trailingData = nFormals + nLocals + nInnerfunctions +  nIdObjectDependencies +
+    static int calculateSize(int nFormals, int nLocals, int nLines, int nInnerfunctions, int nIdObjectDependencies, int nPropertyDependencies) {
+        int trailingData = nFormals + nLocals + nLines + nInnerfunctions +  nIdObjectDependencies +
                 2 * nPropertyDependencies;
         return align(align(sizeof(Function)) + size_t(trailingData) * sizeof(quint32));
     }
diff --git a/src/qml/compiler/qv4compiler.cpp b/src/qml/compiler/qv4compiler.cpp
index 84deb076b3..acfd5c56e7 100644
--- a/src/qml/compiler/qv4compiler.cpp
+++ b/src/qml/compiler/qv4compiler.cpp
@@ -316,6 +316,10 @@ void QV4::Compiler::JSUnitGenerator::writeFunction(char *f, QV4::Compiler::Conte
     function->localsOffset = currentOffset;
     currentOffset += function->nLocals * sizeof(quint32);
 
+    function->nLineNumbers = irFunction->lineNumberMapping.size();
+    function->lineNumberOffset = currentOffset;
+    currentOffset += function->nLineNumbers * sizeof(quint32);
+
     function->nInnerFunctions = irFunction->nestedContexts.size();
 
     function->nRegisters = irFunction->registerCount;
@@ -358,6 +362,11 @@ void QV4::Compiler::JSUnitGenerator::writeFunction(char *f, QV4::Compiler::Conte
     for (int i = 0; i < irFunction->locals.size(); ++i)
         locals[i] = getStringId(irFunction->locals.at(i));
 
+    // write line numbers
+    quint32 *lineNumbers = (quint32 *)(f + function->lineNumberOffset);
+    for (int i = 0; i < irFunction->lineNumberMapping.size(); ++i)
+        lineNumbers[i] = irFunction->lineNumberMapping.at(i);
+
     // write QML dependencies
     quint32_le *writtenDeps = (quint32_le *)(f + function->dependingIdObjectsOffset);
     for (int id : irFunction->idObjectDependencies) {
@@ -428,7 +437,7 @@ QV4::CompiledData::Unit QV4::Compiler::JSUnitGenerator::generateHeader(QV4::Comp
 
         const int qmlIdDepsCount = f->idObjectDependencies.count();
         const int qmlPropertyDepsCount = f->scopeObjectPropertyDependencies.count() + f->contextObjectPropertyDependencies.count();
-        nextOffset += QV4::CompiledData::Function::calculateSize(f->arguments.size(), f->locals.size(), f->nestedContexts.size(), qmlIdDepsCount, qmlPropertyDepsCount);
+        nextOffset += QV4::CompiledData::Function::calculateSize(f->arguments.size(), f->locals.size(), f->lineNumberMapping.size(), f->nestedContexts.size(), qmlIdDepsCount, qmlPropertyDepsCount);
     }
 
     if (option == GenerateWithStringTable) {
diff --git a/src/qml/compiler/qv4compilercontext_p.h b/src/qml/compiler/qv4compilercontext_p.h
index 0a204d8c24..796f313b5c 100644
--- a/src/qml/compiler/qv4compilercontext_p.h
+++ b/src/qml/compiler/qv4compilercontext_p.h
@@ -133,6 +133,7 @@ struct Context {
 
     ControlFlow *controlFlow = 0;
     QByteArray code;
+    QVector<int> lineNumberMapping;
 
     int maxNumberOfArguments = 0;
     bool hasDirectEval = false;
diff --git a/src/qml/compiler/qv4instr_moth.cpp b/src/qml/compiler/qv4instr_moth.cpp
index 9101537236..523fe88c02 100644
--- a/src/qml/compiler/qv4instr_moth.cpp
+++ b/src/qml/compiler/qv4instr_moth.cpp
@@ -59,6 +59,12 @@ static QByteArray alignedNumber(int n) {
     return number;
 }
 
+static QByteArray alignedLineNumber(int line) {
+    if (line > 0)
+        return alignedNumber(static_cast<int>(line));
+    return QByteArray("            ");
+}
+
 static QString toString(QV4::ReturnedValue v)
 {
 #ifdef V4_BOOTSTRAP
@@ -91,7 +97,7 @@ size_t absoluteInstructionOffset(const char *codeStart, const T &instr)
     QDebug d = qDebug(); \
     d.noquote(); \
     d.nospace(); \
-    d << alignedNumber(int(code - start)).constData() << ":    " << #I << " "; \
+    d << alignedLineNumber(line) << alignedNumber(int(code - start)).constData() << ":    " << #I << " "; \
     code += InstrMeta<int(Instr::I)>::Size; \
 
 #define MOTH_END_INSTR(I) } break;
@@ -109,12 +115,18 @@ void dumpConstantTable(const Value *constants, uint count)
           << toString(constants[i].asReturnedValue()).toUtf8().constData() << "\n";
 }
 
-void dumpBytecode(const char *code, int len, int nLocals, int nFormals)
+void dumpBytecode(const char *code, int len, int nLocals, int nFormals, int startLine, const QVector<int> &lineNumberMapping)
 {
+    int lastLine = -1;
     const char *start = code;
     const char *end = code + len;
     while (code < end) {
         const Instr *genericInstr = reinterpret_cast<const Instr *>(code);
+        int line = startLine + ((code == start) ? 0 : lineNumberMapping.lastIndexOf(static_cast<uint>(code - start)) + 1);
+        if (line > lastLine)
+            lastLine = line;
+        else
+            line = -1;
         switch (genericInstr->common.instructionType) {
 
         MOTH_BEGIN_INSTR(LoadReg)
@@ -516,14 +528,10 @@ void dumpBytecode(const char *code, int len, int nLocals, int nFormals)
         MOTH_BEGIN_INSTR(Ret)
         MOTH_END_INSTR(Ret)
 
-    #ifndef QT_NO_QML_DEBUGGER
+#ifndef QT_NO_QML_DEBUGGER
         MOTH_BEGIN_INSTR(Debug)
         MOTH_END_INSTR(Debug)
-
-        MOTH_BEGIN_INSTR(Line)
-            d << instr.lineNumber;
-        MOTH_END_INSTR(Line)
-    #endif // QT_NO_QML_DEBUGGER
+#endif // QT_NO_QML_DEBUGGER
 
         MOTH_BEGIN_INSTR(LoadQmlContext)
             d << instr.result.dump(nFormals);
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index 2ce0ff7b22..588ee7c110 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -64,7 +64,6 @@ QT_BEGIN_NAMESPACE
 #define MOTH_DEBUG_INSTR(F)
 #else
 #define MOTH_DEBUG_INSTR(F) \
-    F(Line, line) \
     F(Debug, debug)
 #endif
 
@@ -236,9 +235,9 @@ inline bool operator!=(const StackSlot &l, const StackSlot &r) { return l.stackS
 // When making changes to the instructions, make sure to bump QV4_DATA_STRUCTURE_VERSION in qv4compileddata_p.h
 
 void dumpConstantTable(const Value *constants, uint count);
-void dumpBytecode(const char *bytecode, int len, int nLocals, int nFormals);
-inline void dumpBytecode(const QByteArray &bytecode, int nLocals, int nFormals) {
-    dumpBytecode(bytecode.constData(), bytecode.length(), nLocals, nFormals);
+void dumpBytecode(const char *bytecode, int len, int nLocals, int nFormals, int startLine = 1, const QVector<int> &lineNumberMapping = QVector<int>());
+inline void dumpBytecode(const QByteArray &bytecode, int nLocals, int nFormals, int startLine = 1, const QVector<int> &lineNumberMapping = QVector<int>()) {
+    dumpBytecode(bytecode.constData(), bytecode.length(), nLocals, nFormals, startLine, lineNumberMapping);
 }
 
 union Instr
@@ -256,13 +255,8 @@ union Instr
     };
 
 #ifndef QT_NO_QML_DEBUGGING
-    struct instr_line {
-        MOTH_INSTR_HEADER
-        qint32 lineNumber;
-    };
     struct instr_debug {
         MOTH_INSTR_HEADER
-        qint32 lineNumber;
     };
 #endif // QT_NO_QML_DEBUGGING
 
@@ -714,7 +708,6 @@ union Instr
 
     instr_common common;
     instr_ret ret;
-    instr_line line;
     instr_debug debug;
     instr_loadConst loadConst;
     instr_loadZero loadZero;