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AK: Tweak ShortString bit layout slightly

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Move the byte count one step to the left in order to make space
for the JS::StringOrSymbol flag.
This commit is contained in:
Andreas Kling 2025-03-18 16:58:31 -05:00
parent 50e9ffbeec
commit b11f3853a8
2 changed files with 5 additions and 3 deletions
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4
AK/StringBase.cpp
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@ -18,7 +18,7 @@ ReadonlyBytes ShortString::bytes() const
size_t ShortString::byte_count() const
{
return byte_count_and_short_string_flag >> 1;
return byte_count_and_short_string_flag >> StringBase::SHORT_STRING_BYTE_COUNT_SHIFT_COUNT;
}
StringBase::StringBase(NonnullRefPtr<Detail::StringData const> data)
@ -78,7 +78,7 @@ size_t StringBase::byte_count() const
{
ASSERT(!is_invalid());
if (is_short_string())
return m_short_string.byte_count_and_short_string_flag >> 1;
return m_short_string.byte_count_and_short_string_flag >> StringBase::SHORT_STRING_BYTE_COUNT_SHIFT_COUNT;
return m_data->byte_count();
}

4
AK/StringBase.h
View file

@ -103,9 +103,11 @@ protected:
private:
friend class ::AK::String;
friend class ::AK::FlyString;
friend struct ::AK::Detail::ShortString;
// NOTE: If the least significant bit of the pointer is set, this is a short string.
static constexpr uintptr_t SHORT_STRING_FLAG = 1;
static constexpr unsigned SHORT_STRING_BYTE_COUNT_SHIFT_COUNT = 2;
explicit StringBase(NonnullRefPtr<Detail::StringData const>);
@ -127,7 +129,7 @@ private:
VERIFY(byte_count <= MAX_SHORT_STRING_BYTE_COUNT);
m_short_string = ShortString {};
m_short_string.byte_count_and_short_string_flag = (byte_count << 1) | SHORT_STRING_FLAG;
m_short_string.byte_count_and_short_string_flag = (byte_count << SHORT_STRING_BYTE_COUNT_SHIFT_COUNT) | SHORT_STRING_FLAG;
return { m_short_string.storage, byte_count };
}