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https://github.com/LadybirdBrowser/ladybird.git
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feb19646df
commit 5f3773b715 increased alignment
for ChunckedBlocks, but not for BigAllocationBlocks.
This is required to make SSE instructions work.
85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
/*
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* Copyright (c) 2018-2020, 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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#pragma once
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#include <AK/IntrusiveList.h>
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#include <AK/Types.h>
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#define MAGIC_PAGE_HEADER 0x42657274 // 'Bert'
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#define MAGIC_BIGALLOC_HEADER 0x42697267 // 'Birg'
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#define MALLOC_SCRUB_BYTE 0xdc
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#define FREE_SCRUB_BYTE 0xed
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#define PAGE_ROUND_UP(x) ((((size_t)(x)) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1)))
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static constexpr unsigned short size_classes[] = { 16, 32, 64, 128, 256, 496, 1008, 2032, 4080, 8176, 16368, 32752, 0 };
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static constexpr size_t num_size_classes = (sizeof(size_classes) / sizeof(unsigned short)) - 1;
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#ifndef NO_TLS
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extern "C" {
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extern __thread bool s_allocation_enabled;
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}
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#endif
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consteval bool check_size_classes_alignment()
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{
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for (size_t i = 0; i < num_size_classes; i++) {
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if ((size_classes[i] % 16) != 0)
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return false;
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}
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return true;
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}
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static_assert(check_size_classes_alignment());
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struct CommonHeader {
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size_t m_magic;
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size_t m_size;
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};
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struct BigAllocationBlock : public CommonHeader {
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BigAllocationBlock(size_t size)
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{
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m_magic = MAGIC_BIGALLOC_HEADER;
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m_size = size;
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}
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alignas(16) unsigned char* m_slot[0];
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};
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struct FreelistEntry {
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FreelistEntry* next;
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};
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struct ChunkedBlock : public CommonHeader {
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static constexpr size_t block_size = 64 * KiB;
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static constexpr size_t block_mask = ~(block_size - 1);
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ChunkedBlock(size_t bytes_per_chunk)
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{
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m_magic = MAGIC_PAGE_HEADER;
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m_size = bytes_per_chunk;
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m_free_chunks = chunk_capacity();
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}
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IntrusiveListNode<ChunkedBlock> m_list_node;
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size_t m_next_lazy_freelist_index { 0 };
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FreelistEntry* m_freelist { nullptr };
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size_t m_free_chunks { 0 };
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alignas(16) unsigned char m_slot[0];
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void* chunk(size_t index)
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{
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return &m_slot[index * m_size];
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}
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bool is_full() const { return m_free_chunks == 0; }
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size_t bytes_per_chunk() const { return m_size; }
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size_t free_chunks() const { return m_free_chunks; }
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size_t used_chunks() const { return chunk_capacity() - m_free_chunks; }
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size_t chunk_capacity() const { return (block_size - sizeof(ChunkedBlock)) / m_size; }
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using List = IntrusiveList<&ChunkedBlock::m_list_node>;
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};
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