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Code Issues Projects Releases Packages Wiki Activity Actions 9

LibJS: Add PutByNumericId and change PutById to be string key only

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Previously, PutById constructed a PropertyKey from the identifier,
which coerced numeric-like strings to numbers. This moves that decision
to bytecode generation: the bytecode generator now emits PutByNumericId
for numeric keys and PutById for string keys. This removes per-execution
parsing from the interpreter.

1.4x speedup on the following microbenchmark:
```js
const o = {};
for (let i = 0; i < 10_000_000; i++) {
    o.a = 1;
    o.b = 2;
    o.c = 3;
}
```
This commit is contained in:
Aliaksandr Kalenik 2025-09-13 16:20:41 +02:00 • committed by Andreas Kling
commit e81833423b
Notes: github-actions[bot] 2025-09-13 18:03:43 +00:00
7 changed files with 83 additions and 7 deletions
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19
Libraries/LibJS/Bytecode/Generator.cpp
View file

@ -775,7 +775,7 @@ CodeGenerationErrorOr<void> Generator::emit_store_to_reference(JS::ASTNode const
emit_put_by_value(object, property, value, Op::PropertyKind::KeyValue, {});
} else if (expression.property().is_identifier()) {
auto identifier_table_ref = intern_identifier(as<Identifier>(expression.property()).string());
emit<Bytecode::Op::PutById>(object, identifier_table_ref, value, Bytecode::Op::PropertyKind::KeyValue, next_property_lookup_cache());
emit_put_by_id(object, identifier_table_ref, value, Bytecode::Op::PropertyKind::KeyValue, next_property_lookup_cache());
} else if (expression.property().is_private_identifier()) {
auto identifier_table_ref = intern_identifier(as<PrivateIdentifier>(expression.property()).string());
emit<Bytecode::Op::PutPrivateById>(object, identifier_table_ref, value);
@ -804,7 +804,7 @@ CodeGenerationErrorOr<void> Generator::emit_store_to_reference(ReferenceOperands
}
if (reference.referenced_identifier.has_value()) {
if (reference.base == reference.this_value)
emit<Bytecode::Op::PutById>(*reference.base, *reference.referenced_identifier, value, Bytecode::Op::PropertyKind::KeyValue, next_property_lookup_cache());
emit_put_by_id(*reference.base, *reference.referenced_identifier, value, Bytecode::Op::PropertyKind::KeyValue, next_property_lookup_cache());
else
emit<Bytecode::Op::PutByIdWithThis>(*reference.base, *reference.this_value, *reference.referenced_identifier, value, Bytecode::Op::PropertyKind::KeyValue, next_property_lookup_cache());
return {};
@ -1153,12 +1153,25 @@ void Generator::emit_get_by_value_with_this(ScopedOperand dst, ScopedOperand bas
emit<Op::GetByValueWithThis>(dst, base, property, this_value);
}
void Generator::emit_put_by_id(Operand base, IdentifierTableIndex property, Operand src, Op::PropertyKind kind, u32 cache_index, Optional<IdentifierTableIndex> base_identifier)
{
auto string = m_identifier_table->get(property);
if (!string.is_empty() && !(string.code_unit_at(0) == '0' && string.length_in_code_units() > 1)) {
auto property_index = string.to_number<u32>(TrimWhitespace::No);
if (property_index.has_value() && property_index.value() < NumericLimits<u32>::max()) {
emit<Op::PutByNumericId>(base, property_index.release_value(), src, kind, cache_index, move(base_identifier));
return;
}
}
emit<Op::PutById>(base, property, src, kind, cache_index, move(base_identifier));
}
void Generator::emit_put_by_value(ScopedOperand base, ScopedOperand property, ScopedOperand src, Bytecode::Op::PropertyKind kind, Optional<IdentifierTableIndex> base_identifier)
{
if (property.operand().is_constant() && get_constant(property).is_string()) {
auto property_key = MUST(get_constant(property).to_property_key(vm()));
if (property_key.is_string()) {
emit<Op::PutById>(base, intern_identifier(property_key.as_string()), src, kind, m_next_property_lookup_cache++, base_identifier);
emit_put_by_id(base, intern_identifier(property_key.as_string()), src, kind, m_next_property_lookup_cache++, base_identifier);
return;
}
}