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LibJS: Prevent object shape transitions during runtime object buildup

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While initialization common runtime objects like functions, prototypes,
etc, we don't really care about tracking transitions for each and every
property added to them.

This patch puts objects into a "disable transitions" mode while we call
initialize() on them. After that, adding more properties will cause new
transitions to be generated and added to the chain.

This gives a ~10% speed-up on test-js. :^)
This commit is contained in:
Andreas Kling 2020-10-05 20:08:14 +02:00
parent 50ab87f651
commit 69bae3fd9a
5 changed files with 23 additions and 1 deletions
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5
Libraries/LibJS/Runtime/Object.cpp
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@ -486,8 +486,11 @@ bool Object::put_own_property(Object& this_object, const StringOrSymbol& propert
if (m_shape->is_unique()) {
m_shape->add_property_to_unique_shape(property_name, attributes);
m_storage.resize(m_shape->property_count());
} else {
} else if (m_transitions_enabled) {
set_shape(*m_shape->create_put_transition(property_name, attributes));
} else {
m_shape->add_property_without_transition(property_name, attributes);
m_storage.resize(m_shape->property_count());
}
metadata = shape().lookup(property_name);
ASSERT(metadata.has_value());