QML: When available, use QQmlAccessors to read properties.

When a property is read from a QObject or the QML scope object, and we
can statically resolve the type to qreal/QObject/int/bool/QString, and
the property has an accessor declared for it, then use that accessor to
do the read.

This collapses the path of e.g.:
  Runtime::getQmlScopeObjectProperty
    -> QObjectWrapper::getProperty
      -> QObjectWrapper::getProperty
        -> LoadProperty
          -> QQmlAccessor::read
(all of which do various checks for all the stuff mentioned above) to:
  Runtime::accessQmlScopeObjectQRealProperty
    -> QQmlAccessor::read
which is a simple 4-line function, and doesn't need to do any check.

According to valgrind, this saves 170 instructions on x86 for the
simple binding:

Item {
    width: height
}

Change-Id: I0761d01e8f1a3c13ecbffe2d8e0317ce9c0a4db0
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/qml/compiler/qv4isel_p.cpp b/src/qml/compiler/qv4isel_p.cpp
index 0ae08160ab..6ba23a0951 100644
--- a/src/qml/compiler/qv4isel_p.cpp
+++ b/src/qml/compiler/qv4isel_p.cpp
@@ -156,14 +156,15 @@ void IRDecoder::visitMove(IR::Move *s)
                     }
                 }
                 if (m->kind == IR::Member::MemberOfQmlScopeObject || m->kind == IR::Member::MemberOfQmlContextObject) {
-                    getQmlContextProperty(m->base, (IR::Member::MemberKind)m->kind, m->property->coreIndex, s->target);
+                    getQmlContextProperty(m->base, (IR::Member::MemberKind)m->kind, m->property,
+                                          m->property->coreIndex, s->target);
                     return;
                 }
-                getQObjectProperty(m->base, m->property->coreIndex, captureRequired, isSingletonProperty, attachedPropertiesId, s->target);
+                getQObjectProperty(m->base, m->property, captureRequired, isSingletonProperty, attachedPropertiesId, s->target);
 #endif // V4_BOOTSTRAP
                 return;
             } else if (m->kind == IR::Member::MemberOfIdObjectsArray) {
-                getQmlContextProperty(m->base, (IR::Member::MemberKind)m->kind, m->idIndex, s->target);
+                getQmlContextProperty(m->base, (IR::Member::MemberKind)m->kind, nullptr, m->idIndex, s->target);
                 return;
             } else if (m->base->asTemp() || m->base->asConst() || m->base->asArgLocal()) {
                 getProperty(m->base, *m->name, s->target);