QML: Do not register static QML dependencies on every call.

QML objects can be re-parented on the fly, resulting in different
dependencies for expressions like 'parent.width'. So, because of this,
dependencies are cleared and re-calculated after every binding
evaluation.

However, dependencies on properties of the scope and context objects
cannot change, because these objects do not get changed for the
life-time of a binding. So we can permanently register them. This is
only done for bindings, not for functions, because those might be
conditionally executed.

According to valgrind, this is a reduction of ~186 instructions on x86
for every evaluation of:
Item {
    height: width
}

Change-Id: Ib095497323d4f08caf712d480007e2627a176369
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 8711bc049a..7a444e8c57 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -1961,6 +1961,7 @@ int Codegen::defineFunction(const QString &name, AST::Node *ast,
     function->maxNumberOfArguments = qMax(_env->maxNumberOfArguments, (int)QV4::Global::ReservedArgumentCount);
     function->isStrict = _env->isStrict;
     function->isNamedExpression = _env->isNamedFunctionExpression;
+    function->isQmlBinding = _env->compilationMode == QmlBinding;
 
     AST::SourceLocation loc = ast->firstSourceLocation();
     function->line = loc.startLine;