ladybird/Libraries/LibJS/Runtime/PrimitiveString.cpp
Andreas Kling 619cd613d0 LibJS: Give VM a cache of single-ASCII-character PrimitiveString
A large number of JS strings are a single ASCII character. This patch
adds a 128-entry cache for those strings to the VM. The cost of the
cache is 1536 byte of GC heap (all in same block) + 2304 bytes malloc.

This avoids a lot of GC heap allocations, and packing all of these
in the same heap block is nice for fragmentation as well.
2020-10-22 17:48:12 +02:00

57 lines
2 KiB
C++

/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibJS/Runtime/PrimitiveString.h>
#include <LibJS/Runtime/VM.h>
namespace JS {
PrimitiveString::PrimitiveString(String string)
: m_string(move(string))
{
}
PrimitiveString::~PrimitiveString()
{
}
PrimitiveString* js_string(Heap& heap, String string)
{
if (string.is_empty())
return &heap.vm().empty_string();
if (string.length() == 1 && (u8)string.characters()[0] < 0x80)
return &heap.vm().single_ascii_character_string(string.characters()[0]);
return heap.allocate_without_global_object<PrimitiveString>(move(string));
}
PrimitiveString* js_string(VM& vm, String string)
{
return js_string(vm.heap(), move(string));
}
}