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LibJS: Add inline caching for adding new own properties to objects

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We already had IC support in PutById for the following cases:
- Changing an existing own property
- Calling a setter located in the prototype chain

This was enough to speed up code where structurally identical objects
(same shape) are processed in a loop:
```js
const arr = [{ a: 1 }, { a: 2 }, { a: 3 }];
for (let obj of arr) {
    obj.a += 1;
}
```

However, creating structurally identical objects in a loop was still
slow:
```js
for (let i = 0; i < 10_000_000; i++) {
    const o = {};
    o.a = 1;
    o.b = 2;
    o.c = 3;
}
```

This change addresses that by adding a new IC type that caches both the
source and target shapes, allowing property additions to be fast-pathed
by directly jumping to the shape that already includes the new property.
This commit is contained in:
Aliaksandr Kalenik 2025-09-15 17:23:39 +02:00 • committed by Andreas Kling
parent a54215c07d
commit d45f8a3081
Notes: github-actions[bot] 2025-09-17 10:45:37 +00:00
21 changed files with 162 additions and 75 deletions
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4
Libraries/LibJS/Runtime/ModuleNamespaceObject.cpp
View file

@ -136,7 +136,7 @@ ThrowCompletionOr<bool> ModuleNamespaceObject::internal_has_property(PropertyKey
}
// 10.4.6.8 [[Get]] ( P, Receiver ), https://tc39.es/ecma262/#sec-module-namespace-exotic-objects-get-p-receiver
ThrowCompletionOr<Value> ModuleNamespaceObject::internal_get(PropertyKey const& property_key, Value receiver, CacheablePropertyMetadata* cacheable_metadata, PropertyLookupPhase phase) const
ThrowCompletionOr<Value> ModuleNamespaceObject::internal_get(PropertyKey const& property_key, Value receiver, CacheableGetPropertyMetadata* cacheable_metadata, PropertyLookupPhase phase) const
{
auto& vm = this->vm();
@ -183,7 +183,7 @@ ThrowCompletionOr<Value> ModuleNamespaceObject::internal_get(PropertyKey const&
}
// 10.4.6.9 [[Set]] ( P, V, Receiver ), https://tc39.es/ecma262/#sec-module-namespace-exotic-objects-set-p-v-receiver
ThrowCompletionOr<bool> ModuleNamespaceObject::internal_set(PropertyKey const&, Value, Value, CacheablePropertyMetadata*, PropertyLookupPhase)
ThrowCompletionOr<bool> ModuleNamespaceObject::internal_set(PropertyKey const&, Value, Value, CacheableSetPropertyMetadata*, PropertyLookupPhase)
{
// 1. Return false.
return false;