Use QHash instead of QMap for resolved types

This vastly speeds up resolved type reference lookups in
QQmlObjectCreator::createInstance, which translates to significant
improvements in qmlbench:
perf record -b ./src/qmlbench --shell frame-count delegates_qobject.qml
went from roughly 730 frames to > 800 locally.

To have a stable order in the hash, we simply sort a tempory vector of
keys. As this happens only once, the overhead is negligible and
partially offset by the better memory locality of the QHash anyway.

Task-number: QTBUG-88672
Change-Id: Ib547a87fd0d2d81f366ea927ade232f33b3d3788
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 1 insertions, 3 deletions

diff --git a/src/qml/jsruntime/qv4executablecompilationunit_p.h b/src/qml/jsruntime/qv4executablecompilationunit_p.h
index 3dc0e58ca5..9ceec1fbf7 100644
--- a/src/qml/jsruntime/qv4executablecompilationunit_p.h
+++ b/src/qml/jsruntime/qv4executablecompilationunit_p.h
@@ -92,9 +92,7 @@ typedef QVector<QQmlPropertyData*> BindingPropertyData;
 class CompilationUnitMapper;
 class ResolvedTypeReference;
 // map from name index
-// While this could be a hash, a map is chosen here to provide a stable
-// order, which is used to calculating a check-sum on dependent meta-objects.
-struct ResolvedTypeReferenceMap: public QMap<int, ResolvedTypeReference*>
+struct ResolvedTypeReferenceMap: public QHash<int, ResolvedTypeReference*>
 {
     bool addToHash(QCryptographicHash *hash, QQmlEngine *engine) const;
 };