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LibJS: Avoid function call if @@hasInstance is default implementation

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This makes the instanceof operator signficantly faster by avoiding a
generic function call to @@hasInstance unless it has been overridden.

1.15x speed-up on Octane/earley-boyer.js
This commit is contained in:
Andreas Kling 2025-10-13 12:21:59 +02:00 • committed by Andreas Kling
parent 5a7b0a07cb
commit 0e4450f4b3
Notes: github-actions[bot] 2025-10-13 15:18:08 +00:00
5 changed files with 12 additions and 1 deletions
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6
Libraries/LibJS/Runtime/Value.cpp
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@ -2172,6 +2172,12 @@ ThrowCompletionOr<Value> instance_of(VM& vm, Value value, Value target)
// 3. If instOfHandler is not undefined, then
if (instance_of_handler) {
// OPTIMIZATION: If the handler is the default OrdinaryHasInstance, we can skip doing a generic call.
if (auto* native_function = as_if<NativeFunction>(*instance_of_handler)) {
if (native_function->builtin() == Bytecode::Builtin::OrdinaryHasInstance) {
return ordinary_has_instance(vm, value, target);
}
}
// a. Return ToBoolean(? Call(instOfHandler, target, « V »)).
return Value(TRY(call(vm, *instance_of_handler, target, value)).to_boolean());
}