Optimize array access

Avoid the expensive modulo operation when indexing into an array,
and do a simple conditional subtraction instead.

Change-Id: I57a78c0cf94b010e4bc226b9b2a5c2e3251498f8
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/qml/jsruntime/qv4arraydata_p.h b/src/qml/jsruntime/qv4arraydata_p.h
index e1de2e82e6..5028778877 100644
--- a/src/qml/jsruntime/qv4arraydata_p.h
+++ b/src/qml/jsruntime/qv4arraydata_p.h
@@ -144,7 +144,7 @@ DECLARE_HEAP_OBJECT(ArrayData, Base) {
 V4_ASSERT_IS_TRIVIAL(ArrayData)
 
 struct SimpleArrayData : public ArrayData {
-    uint mappedIndex(uint index) const { return (index + offset) % values.alloc; }
+    uint mappedIndex(uint index) const { index += offset; if (index > values.alloc) index -= values.alloc; return index; }
     const Value &data(uint index) const { return values[mappedIndex(index)]; }
     void setData(EngineBase *e, uint index, Value newVal) {
         values.set(e, mappedIndex(index), newVal);