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LibJS/Bytecode: Make constant deduplication a bit smarter

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Instead of scanning through the list of seen constants, we now have a
more structured storage of the constants true, false, null, undefined,
and every possible Int32 value.

This fixes an O(n^2) issue found by Kraken/json-stringify-tinderbox.js
This commit is contained in:
Andreas Kling 2024-05-14 14:28:22 +02:00
parent 044539c60b
commit ae90e26315
Notes: sideshowbarker 2024-07-16 20:21:48 +09:00
3 changed files with 54 additions and 15 deletions
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42
Userland/Libraries/LibJS/Bytecode/Generator.cpp
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@ -1191,4 +1191,46 @@ ScopedOperand Generator::copy_if_needed_to_preserve_evaluation_order(ScopedOpera
return new_register;
}
ScopedOperand Generator::add_constant(Value value)
{
auto append_new_constant = [&] {
m_constants.append(value);
return ScopedOperand { *this, Operand(Operand::Type::Constant, m_constants.size() - 1) };
};
if (value.is_boolean()) {
if (value.as_bool()) {
if (!m_true_constant.has_value())
m_true_constant = append_new_constant();
return m_true_constant.value();
} else {
if (!m_false_constant.has_value())
m_false_constant = append_new_constant();
return m_false_constant.value();
}
}
if (value.is_undefined()) {
if (!m_undefined_constant.has_value())
m_undefined_constant = append_new_constant();
return m_undefined_constant.value();
}
if (value.is_null()) {
if (!m_null_constant.has_value())
m_null_constant = append_new_constant();
return m_null_constant.value();
}
if (value.is_empty()) {
if (!m_empty_constant.has_value())
m_empty_constant = append_new_constant();
return m_empty_constant.value();
}
if (value.is_int32()) {
auto as_int32 = value.as_i32();
return m_int32_constants.ensure(as_int32, [&] {
return append_new_constant();
});
}
return append_new_constant();
}
}