3 files changed, 46 insertions, 19 deletions
diff --git a/src/qml/compiler/qqmlirbuilder.cpp b/src/qml/compiler/qqmlirbuilder.cpp
index e63aa3b66d..6f46648572 100644
--- a/src/qml/compiler/qqmlirbuilder.cpp
+++ b/src/qml/compiler/qqmlirbuilder.cpp
@@ -1565,9 +1565,6 @@ void QmlUnitGenerator::generate(Document &output, const QV4::CompiledData::Depen
                 break;
             }
         }
-        // This unit's memory was allocated with malloc on the heap, so it's
-        // definitely not suitable for StaticData access.
-        createdUnit->flags &= ~QV4::CompiledData::Unit::StaticData;
 
         if (dependencyHasher) {
             const QByteArray checksum = dependencyHasher();
diff --git a/src/qml/compiler/qv4compileddata.cpp b/src/qml/compiler/qv4compileddata.cpp
index 091c29c8c7..71015107ad 100644
--- a/src/qml/compiler/qv4compileddata.cpp
+++ b/src/qml/compiler/qv4compileddata.cpp
@@ -82,14 +82,8 @@ CompilationUnit::~CompilationUnit()
             free(const_cast<QmlUnit *>(qmlData));
         qmlData = nullptr;
 
-#ifndef V4_BOOTSTRAP
         if (!(data->flags & QV4::CompiledData::Unit::StaticData))
             free(const_cast<Unit *>(data));
-#else
-        // Unconditionally free the memory. In the dev tools we create units that have
-        // the flag set and will be saved to disk, so intended to persist later.
-        free(const_cast<Unit *>(data));
-#endif
     }
     data = nullptr;
 #if Q_BYTE_ORDER == Q_BIG_ENDIAN
@@ -113,16 +107,9 @@ bool CompilationUnit::saveToDisk(const QString &outputFileName, QString *errorSt
         return false;
     }
 
-    QByteArray modifiedUnit;
-    modifiedUnit.resize(data->unitSize);
-    memcpy(modifiedUnit.data(), data, data->unitSize);
-    const char *dataPtr = modifiedUnit.data();
-    Unit *unitPtr;
-    memcpy(&unitPtr, &dataPtr, sizeof(unitPtr));
-    unitPtr->flags |= Unit::StaticData;
-
-    qint64 headerWritten = cacheFile.write(modifiedUnit);
-    if (headerWritten != modifiedUnit.size()) {
+    SaveableUnitPointer saveable(this);
+    qint64 headerWritten = cacheFile.write(saveable.data<char>(), saveable.size());
+    if (headerWritten != saveable.size()) {
         *errorString = cacheFile.errorString();
         return false;
     }
diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index 9301939bff..629adf8231 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -1158,6 +1158,49 @@ public:
     bool saveToDisk(const QString &outputFileName, QString *errorString) const;
 };
 
+class SaveableUnitPointer
+{
+    Q_DISABLE_COPY_MOVE(SaveableUnitPointer)
+public:
+    SaveableUnitPointer(const CompilationUnit *unit, quint32 temporaryFlags = Unit::StaticData) :
+          unit(unit)
+    {
+        quint32_le &unitFlags = mutableFlags();
+        quint32 origFlags = unitFlags;
+        unitFlags |= temporaryFlags;
+        changedFlags = origFlags ^ unitFlags;
+    }
+
+    ~SaveableUnitPointer()
+    {
+        mutableFlags() ^= changedFlags;
+    }
+
+    const CompilationUnit *operator->() const { return unit; }
+    const CompilationUnit &operator*() const { return *unit; }
+    operator const CompilationUnit *() { return unit; }
+
+    template<typename Char>
+    const Char *data() const
+    {
+        Q_STATIC_ASSERT(sizeof(Char) == 1);
+        const Char *dataPtr;
+        memcpy(&dataPtr, &unit->data, sizeof(dataPtr));
+        return dataPtr;
+    }
+
+    quint32 size() const
+    {
+        return unit->data->unitSize;
+    }
+
+private:
+    quint32_le &mutableFlags() { return const_cast<Unit *>(unit->unitData())->flags; };
+    const CompilationUnit *unit;
+    quint32 changedFlags;
+};
+
+
 } // CompiledData namespace
 } // QV4 namespace