QML: Make Heap::Object and all subclasses trivial

GCC6 might dead-store-eliminate out our secret write to Base::mmdata,
because it expects all memory content to be "undefined" before
constructor calls. Clang might take the same approach if the constructor
of Heap::Object is removed.

By making these structs trivial, it also makes them memcpy-able.

Change-Id: I055b2ad28311b997fbe059849ebda4d5894eaa9b
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 38 insertions, 35 deletions

diff --git a/src/qml/jsruntime/qv4errorobject.cpp b/src/qml/jsruntime/qv4errorobject.cpp
index bb5d32cbd7..597ded6ae1 100644
--- a/src/qml/jsruntime/qv4errorobject.cpp
+++ b/src/qml/jsruntime/qv4errorobject.cpp
@@ -67,8 +67,9 @@
 
 using namespace QV4;
 
-Heap::ErrorObject::ErrorObject()
+void Heap::ErrorObject::init()
 {
+    Object::init();
     stackTrace = nullptr;
 
     Scope scope(internalClass->engine);
@@ -83,8 +84,9 @@ Heap::ErrorObject::ErrorObject()
     *propertyData(QV4::ErrorObject::Index_LineNumber) = Encode::undefined();
 }
 
-Heap::ErrorObject::ErrorObject(const Value &message, ErrorType t)
+void Heap::ErrorObject::init(const Value &message, ErrorType t)
 {
+    Object::init();
     errorType = t;
 
     Scope scope(internalClass->engine);
@@ -103,8 +105,9 @@ Heap::ErrorObject::ErrorObject(const Value &message, ErrorType t)
         *propertyData(QV4::ErrorObject::Index_Message) = message;
 }
 
-Heap::ErrorObject::ErrorObject(const Value &message, const QString &fileName, int line, int column, ErrorObject::ErrorType t)
+void Heap::ErrorObject::init(const Value &message, const QString &fileName, int line, int column, ErrorObject::ErrorType t)
 {
+    Object::init();
     errorType = t;
 
     Scope scope(internalClass->engine);
@@ -183,44 +186,44 @@ DEFINE_OBJECT_VTABLE(ErrorObject);
 
 DEFINE_OBJECT_VTABLE(SyntaxErrorObject);
 
-Heap::SyntaxErrorObject::SyntaxErrorObject(const Value &msg)
-    : Heap::ErrorObject(msg, SyntaxError)
+void Heap::SyntaxErrorObject::init(const Value &msg)
 {
+    Heap::ErrorObject::init(msg, SyntaxError);
 }
 
-Heap::SyntaxErrorObject::SyntaxErrorObject(const Value &msg, const QString &fileName, int lineNumber, int columnNumber)
-    : Heap::ErrorObject(msg, fileName, lineNumber, columnNumber, SyntaxError)
+void Heap::SyntaxErrorObject::init(const Value &msg, const QString &fileName, int lineNumber, int columnNumber)
 {
+    Heap::ErrorObject::init(msg, fileName, lineNumber, columnNumber, SyntaxError);
 }
 
-Heap::EvalErrorObject::EvalErrorObject(const Value &message)
-    : Heap::ErrorObject(message, EvalError)
+void Heap::EvalErrorObject::init(const Value &message)
 {
+    Heap::ErrorObject::init(message, EvalError);
 }
 
-Heap::RangeErrorObject::RangeErrorObject(const Value &message)
-    : Heap::ErrorObject(message, RangeError)
+void Heap::RangeErrorObject::init(const Value &message)
 {
+    Heap::ErrorObject::init(message, RangeError);
 }
 
-Heap::ReferenceErrorObject::ReferenceErrorObject(const Value &message)
-    : Heap::ErrorObject(message, ReferenceError)
+void Heap::ReferenceErrorObject::init(const Value &message)
 {
+    Heap::ErrorObject::init(message, ReferenceError);
 }
 
-Heap::ReferenceErrorObject::ReferenceErrorObject(const Value &msg, const QString &fileName, int lineNumber, int columnNumber)
-    : Heap::ErrorObject(msg, fileName, lineNumber, columnNumber, ReferenceError)
+void Heap::ReferenceErrorObject::init(const Value &msg, const QString &fileName, int lineNumber, int columnNumber)
 {
+    Heap::ErrorObject::init(msg, fileName, lineNumber, columnNumber, ReferenceError);
 }
 
-Heap::TypeErrorObject::TypeErrorObject(const Value &message)
-    : Heap::ErrorObject(message, TypeError)
+void Heap::TypeErrorObject::init(const Value &message)
 {
+    Heap::ErrorObject::init(message, TypeError);
 }
 
-Heap::URIErrorObject::URIErrorObject(const Value &message)
-    : Heap::ErrorObject(message, URIError)
+void Heap::URIErrorObject::init(const Value &message)
 {
+    Heap::ErrorObject::init(message, URIError);
 }
 
 DEFINE_OBJECT_VTABLE(ErrorCtor);
@@ -231,14 +234,14 @@ DEFINE_OBJECT_VTABLE(SyntaxErrorCtor);
 DEFINE_OBJECT_VTABLE(TypeErrorCtor);
 DEFINE_OBJECT_VTABLE(URIErrorCtor);
 
-Heap::ErrorCtor::ErrorCtor(QV4::ExecutionContext *scope)
-    : Heap::FunctionObject(scope, QStringLiteral("Error"))
+void Heap::ErrorCtor::init(QV4::ExecutionContext *scope)
 {
+    Heap::FunctionObject::init(scope, QStringLiteral("Error"));
 }
 
-Heap::ErrorCtor::ErrorCtor(QV4::ExecutionContext *scope, const QString &name)
-    : Heap::FunctionObject(scope, name)
+void Heap::ErrorCtor::init(QV4::ExecutionContext *scope, const QString &name)
 {
+    Heap::FunctionObject::init(scope, name);
 }
 
 void ErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
@@ -252,9 +255,9 @@ void ErrorCtor::call(const Managed *that, Scope &scope, CallData *callData)
     static_cast<const Object *>(that)->construct(scope, callData);
 }
 
-Heap::EvalErrorCtor::EvalErrorCtor(QV4::ExecutionContext *scope)
-    : Heap::ErrorCtor(scope, QStringLiteral("EvalError"))
+void Heap::EvalErrorCtor::init(QV4::ExecutionContext *scope)
 {
+    Heap::ErrorCtor::init(scope, QStringLiteral("EvalError"));
 }
 
 void EvalErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
@@ -263,9 +266,9 @@ void EvalErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
     scope.result = ErrorObject::create<EvalErrorObject>(scope.engine, v);
 }
 
-Heap::RangeErrorCtor::RangeErrorCtor(QV4::ExecutionContext *scope)
-    : Heap::ErrorCtor(scope, QStringLiteral("RangeError"))
+void Heap::RangeErrorCtor::init(QV4::ExecutionContext *scope)
 {
+    Heap::ErrorCtor::init(scope, QStringLiteral("RangeError"));
 }
 
 void RangeErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
@@ -274,9 +277,9 @@ void RangeErrorCtor::construct(const Managed *, Scope &scope, CallData *callData
     scope.result = ErrorObject::create<RangeErrorObject>(scope.engine, v);
 }
 
-Heap::ReferenceErrorCtor::ReferenceErrorCtor(QV4::ExecutionContext *scope)
-    : Heap::ErrorCtor(scope, QStringLiteral("ReferenceError"))
+void Heap::ReferenceErrorCtor::init(QV4::ExecutionContext *scope)
 {
+    Heap::ErrorCtor::init(scope, QStringLiteral("ReferenceError"));
 }
 
 void ReferenceErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
@@ -285,9 +288,9 @@ void ReferenceErrorCtor::construct(const Managed *, Scope &scope, CallData *call
     scope.result = ErrorObject::create<ReferenceErrorObject>(scope.engine, v);
 }
 
-Heap::SyntaxErrorCtor::SyntaxErrorCtor(QV4::ExecutionContext *scope)
-    : Heap::ErrorCtor(scope, QStringLiteral("SyntaxError"))
+void Heap::SyntaxErrorCtor::init(QV4::ExecutionContext *scope)
 {
+    Heap::ErrorCtor::init(scope, QStringLiteral("SyntaxError"));
 }
 
 void SyntaxErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
@@ -296,9 +299,9 @@ void SyntaxErrorCtor::construct(const Managed *, Scope &scope, CallData *callDat
     scope.result = ErrorObject::create<SyntaxErrorObject>(scope.engine, v);
 }
 
-Heap::TypeErrorCtor::TypeErrorCtor(QV4::ExecutionContext *scope)
-    : Heap::ErrorCtor(scope, QStringLiteral("TypeError"))
+void Heap::TypeErrorCtor::init(QV4::ExecutionContext *scope)
 {
+    Heap::ErrorCtor::init(scope, QStringLiteral("TypeError"));
 }
 
 void TypeErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
@@ -307,9 +310,9 @@ void TypeErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)
     scope.result = ErrorObject::create<TypeErrorObject>(scope.engine, v);
 }
 
-Heap::URIErrorCtor::URIErrorCtor(QV4::ExecutionContext *scope)
-    : Heap::ErrorCtor(scope, QStringLiteral("URIError"))
+void Heap::URIErrorCtor::init(QV4::ExecutionContext *scope)
 {
+    Heap::ErrorCtor::init(scope, QStringLiteral("URIError"));
 }
 
 void URIErrorCtor::construct(const Managed *, Scope &scope, CallData *callData)