Fix line number mapping to work with non increasing line numbers

The old map assumed that line numbers are always increasing, something
that isn't always true. So move to a format where we map blocks of
bytecode to a line number instead.

Change-Id: I1cd9dd1329d415122cd3d560294ef53007f879f8
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>

6 files changed, 41 insertions, 23 deletions

diff --git a/src/qml/compiler/qv4bytecodegenerator.cpp b/src/qml/compiler/qv4bytecodegenerator.cpp
index 9feafb8bd4..dfdb71b253 100644
--- a/src/qml/compiler/qv4bytecodegenerator.cpp
+++ b/src/qml/compiler/qv4bytecodegenerator.cpp
@@ -40,6 +40,7 @@
 #include <private/qv4bytecodegenerator_p.h>
 #include <private/qv4compilercontext_p.h>
 #include <private/qqmljsastfwd_p.h>
+#include <private/qv4compileddata_p.h>
 
 QT_USE_NAMESPACE
 using namespace QV4;
@@ -161,15 +162,16 @@ void BytecodeGenerator::finalize(Compiler::Context *context)
 
     // collect content and line numbers
     QByteArray code;
-    QVector<int> lineNumbers;
-    currentLine = startLine;
+    QVector<CompiledData::CodeOffsetToLine> lineNumbers;
+    currentLine = -1;
+    Q_UNUSED(startLine);
     for (const auto &i : qAsConst(instructions)) {
         if (i.line != currentLine) {
-            Q_ASSERT(i.line > currentLine);
-            while (currentLine < i.line) {
-                lineNumbers.append(code.size());
-                ++currentLine;
-            }
+            currentLine = i.line;
+            CompiledData::CodeOffsetToLine entry;
+            entry.codeOffset = code.size();
+            entry.line = currentLine;
+            lineNumbers.append(entry);
         }
         code.append(i.packed, i.size);
     }
diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index 445c3c7091..6c8e2bc121 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 0x13
+#define QV4_DATA_STRUCTURE_VERSION 0x14
 
 class QIODevice;
 class QQmlPropertyCache;
@@ -194,6 +194,11 @@ struct String
     }
 };
 
+struct CodeOffsetToLine {
+    quint32_le codeOffset;
+    quint32_le line;
+};
+
 // Function is aligned on an 8-byte boundary to make sure there are no bus errors or penalties
 // for unaligned access. The ordering of the fields is also from largest to smallest.
 struct Function
@@ -242,7 +247,7 @@ 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 CodeOffsetToLine *lineNumberTable() const { return reinterpret_cast<const CodeOffsetToLine *>(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); }
@@ -255,9 +260,9 @@ struct Function
     inline bool hasQmlDependencies() const { return nDependingIdObjects > 0 || nDependingContextProperties > 0 || nDependingScopeProperties > 0; }
 
     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));
+        int trailingData = (nFormals + nLocals + nInnerfunctions +  nIdObjectDependencies +
+                2 * nPropertyDependencies)*sizeof (quint32) + nLines*sizeof(CodeOffsetToLine);
+        return align(align(sizeof(Function)) + size_t(trailingData));
     }
 
     static size_t align(size_t a) {
diff --git a/src/qml/compiler/qv4compiler.cpp b/src/qml/compiler/qv4compiler.cpp
index acfd5c56e7..aaa06efa8c 100644
--- a/src/qml/compiler/qv4compiler.cpp
+++ b/src/qml/compiler/qv4compiler.cpp
@@ -318,7 +318,7 @@ void QV4::Compiler::JSUnitGenerator::writeFunction(char *f, QV4::Compiler::Conte
 
     function->nLineNumbers = irFunction->lineNumberMapping.size();
     function->lineNumberOffset = currentOffset;
-    currentOffset += function->nLineNumbers * sizeof(quint32);
+    currentOffset += function->nLineNumbers * sizeof(CompiledData::CodeOffsetToLine);
 
     function->nInnerFunctions = irFunction->nestedContexts.size();
 
@@ -363,9 +363,7 @@ void QV4::Compiler::JSUnitGenerator::writeFunction(char *f, QV4::Compiler::Conte
         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);
+    memcpy(f + function->lineNumberOffset, irFunction->lineNumberMapping.constData(), irFunction->lineNumberMapping.size()*sizeof(CompiledData::CodeOffsetToLine));
 
     // write QML dependencies
     quint32_le *writtenDeps = (quint32_le *)(f + function->dependingIdObjectsOffset);
diff --git a/src/qml/compiler/qv4compilercontext_p.h b/src/qml/compiler/qv4compilercontext_p.h
index 796f313b5c..b796a5f149 100644
--- a/src/qml/compiler/qv4compilercontext_p.h
+++ b/src/qml/compiler/qv4compilercontext_p.h
@@ -52,6 +52,7 @@
 
 #include "private/qv4global_p.h"
 #include <private/qqmljsast_p.h>
+#include <private/qv4compileddata_p.h>
 #include <QtCore/QStringList>
 #include <QtCore/QDateTime>
 #include <QtCore/QStack>
@@ -133,7 +134,7 @@ struct Context {
 
     ControlFlow *controlFlow = 0;
     QByteArray code;
-    QVector<int> lineNumberMapping;
+    QVector<CompiledData::CodeOffsetToLine> lineNumberMapping;
 
     int maxNumberOfArguments = 0;
     bool hasDirectEval = false;
diff --git a/src/qml/compiler/qv4instr_moth.cpp b/src/qml/compiler/qv4instr_moth.cpp
index 056e8d6624..c51f604500 100644
--- a/src/qml/compiler/qv4instr_moth.cpp
+++ b/src/qml/compiler/qv4instr_moth.cpp
@@ -38,6 +38,7 @@
 ****************************************************************************/
 
 #include "qv4instr_moth_p.h"
+#include <private/qv4compileddata_p.h>
 
 using namespace QV4;
 using namespace QV4::Moth;
@@ -117,17 +118,21 @@ 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, int startLine, const QVector<int> &lineNumberMapping)
+void dumpBytecode(const char *code, int len, int nLocals, int nFormals, int /*startLine*/, const QVector<CompiledData::CodeOffsetToLine> &lineNumberMapping)
 {
-
     MOTH_JUMP_TABLE;
 
+    auto findLine = [](const CompiledData::CodeOffsetToLine &entry, uint offset) {
+        return entry.codeOffset < offset;
+    };
+
     int lastLine = -1;
     const char *start = code;
     const char *end = code + len;
     while (code < end) {
-        int line = startLine + ((code == start) ? 0 : lineNumberMapping.lastIndexOf(static_cast<uint>(code - start)) + 1);
-        if (line > lastLine)
+        const CompiledData::CodeOffsetToLine *codeToLine = std::lower_bound(lineNumberMapping.constBegin(), lineNumberMapping.constEnd(), static_cast<uint>(code - start) + 1, findLine) - 1;
+        int line = codeToLine->line;
+        if (line != lastLine)
             lastLine = line;
         else
             line = -1;
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index dc262f5a37..cc26c88155 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -414,6 +414,11 @@ QT_BEGIN_NAMESPACE
 #endif
 
 namespace QV4 {
+
+namespace CompiledData {
+struct CodeOffsetToLine;
+}
+
 namespace Moth {
 
 class StackSlot {
@@ -467,8 +472,10 @@ 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, 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>()) {
+void dumpBytecode(const char *bytecode, int len, int nLocals, int nFormals, int startLine = 1,
+                  const QVector<CompiledData::CodeOffsetToLine> &lineNumberMapping = QVector<CompiledData::CodeOffsetToLine>());
+inline void dumpBytecode(const QByteArray &bytecode, int nLocals, int nFormals, int startLine = 1,
+                         const QVector<CompiledData::CodeOffsetToLine> &lineNumberMapping = QVector<CompiledData::CodeOffsetToLine>()) {
     dumpBytecode(bytecode.constData(), bytecode.length(), nLocals, nFormals, startLine, lineNumberMapping);
 }