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https://github.com/LadybirdBrowser/ladybird.git
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f290c59dd8
VM now has a string cache which tracks all live PrimitiveStrings and reuses an existing one if possible. This drastically reduces the number of GC-allocated strings in many real-word situations.
109 lines
2.5 KiB
C++
109 lines
2.5 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/CharacterTypes.h>
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#include <AK/Utf16View.h>
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#include <LibJS/Runtime/PrimitiveString.h>
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#include <LibJS/Runtime/VM.h>
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namespace JS {
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PrimitiveString::PrimitiveString(String string)
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: m_utf8_string(move(string))
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, m_has_utf8_string(true)
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{
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}
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PrimitiveString::PrimitiveString(Utf16String string)
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: m_utf16_string(move(string))
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, m_has_utf16_string(true)
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{
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}
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PrimitiveString::~PrimitiveString()
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{
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vm().string_cache().remove(m_utf8_string);
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}
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String const& PrimitiveString::string() const
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{
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if (!m_has_utf8_string) {
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m_utf8_string = m_utf16_string.to_utf8();
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m_has_utf8_string = true;
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}
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return m_utf8_string;
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}
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Utf16String const& PrimitiveString::utf16_string() const
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{
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if (!m_has_utf16_string) {
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m_utf16_string = Utf16String(m_utf8_string);
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m_has_utf16_string = true;
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}
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return m_utf16_string;
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}
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Utf16View PrimitiveString::utf16_string_view() const
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{
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return utf16_string().view();
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}
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PrimitiveString* js_string(Heap& heap, Utf16View const& view)
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{
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return js_string(heap, Utf16String(view));
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}
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PrimitiveString* js_string(VM& vm, Utf16View const& view)
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{
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return js_string(vm.heap(), view);
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}
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PrimitiveString* js_string(Heap& heap, Utf16String string)
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{
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if (string.is_empty())
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return &heap.vm().empty_string();
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if (string.length_in_code_units() == 1) {
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u16 code_unit = string.code_unit_at(0);
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if (is_ascii(code_unit))
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return &heap.vm().single_ascii_character_string(static_cast<u8>(code_unit));
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}
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return heap.allocate_without_global_object<PrimitiveString>(move(string));
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}
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PrimitiveString* js_string(VM& vm, Utf16String string)
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{
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return js_string(vm.heap(), move(string));
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}
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PrimitiveString* js_string(Heap& heap, String string)
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{
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if (string.is_empty())
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return &heap.vm().empty_string();
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if (string.length() == 1) {
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auto ch = static_cast<u8>(string.characters()[0]);
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if (is_ascii(ch))
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return &heap.vm().single_ascii_character_string(ch);
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}
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auto& string_cache = heap.vm().string_cache();
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auto it = string_cache.find(string);
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if (it == string_cache.end()) {
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auto* new_string = heap.allocate_without_global_object<PrimitiveString>(string);
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string_cache.set(move(string), new_string);
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return new_string;
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}
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return it->value;
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}
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PrimitiveString* js_string(VM& vm, String string)
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{
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return js_string(vm.heap(), move(string));
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}
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}
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