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(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED) Since all of these checks are done in release builds as well, let's rename them to VERIFY to prevent confusion, as everyone is used to assertions being compiled out in release. We can introduce a new ASSERT macro that is specifically for debug checks, but I'm doing this wholesale conversion first since we've accumulated thousands of these already, and it's not immediately obvious which ones are suitable for ASSERT.
330 lines
9.9 KiB
C++
330 lines
9.9 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/Badge.h>
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#include <AK/Debug.h>
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#include <AK/HashTable.h>
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#include <AK/StackInfo.h>
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#include <AK/TemporaryChange.h>
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#include <LibCore/ElapsedTimer.h>
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#include <LibJS/Heap/Allocator.h>
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#include <LibJS/Heap/Handle.h>
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#include <LibJS/Heap/Heap.h>
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#include <LibJS/Heap/HeapBlock.h>
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#include <LibJS/Interpreter.h>
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#include <LibJS/Runtime/Object.h>
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#include <setjmp.h>
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namespace JS {
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Heap::Heap(VM& vm)
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: m_vm(vm)
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{
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m_allocators.append(make<Allocator>(16));
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m_allocators.append(make<Allocator>(32));
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m_allocators.append(make<Allocator>(64));
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m_allocators.append(make<Allocator>(128));
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m_allocators.append(make<Allocator>(256));
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m_allocators.append(make<Allocator>(512));
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m_allocators.append(make<Allocator>(1024));
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m_allocators.append(make<Allocator>(3172));
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}
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Heap::~Heap()
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{
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collect_garbage(CollectionType::CollectEverything);
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}
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ALWAYS_INLINE Allocator& Heap::allocator_for_size(size_t cell_size)
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{
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for (auto& allocator : m_allocators) {
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if (allocator->cell_size() >= cell_size)
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return *allocator;
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}
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VERIFY_NOT_REACHED();
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}
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Cell* Heap::allocate_cell(size_t size)
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{
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if (should_collect_on_every_allocation()) {
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collect_garbage();
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} else if (m_allocations_since_last_gc > m_max_allocations_between_gc) {
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m_allocations_since_last_gc = 0;
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collect_garbage();
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} else {
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++m_allocations_since_last_gc;
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}
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auto& allocator = allocator_for_size(size);
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return allocator.allocate_cell(*this);
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}
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void Heap::collect_garbage(CollectionType collection_type, bool print_report)
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{
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VERIFY(!m_collecting_garbage);
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TemporaryChange change(m_collecting_garbage, true);
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Core::ElapsedTimer collection_measurement_timer;
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collection_measurement_timer.start();
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if (collection_type == CollectionType::CollectGarbage) {
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if (m_gc_deferrals) {
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m_should_gc_when_deferral_ends = true;
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return;
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}
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HashTable<Cell*> roots;
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gather_roots(roots);
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mark_live_cells(roots);
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}
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sweep_dead_cells(print_report, collection_measurement_timer);
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}
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void Heap::gather_roots(HashTable<Cell*>& roots)
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{
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vm().gather_roots(roots);
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gather_conservative_roots(roots);
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for (auto* handle : m_handles)
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roots.set(handle->cell());
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for (auto* list : m_marked_value_lists) {
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for (auto& value : list->values()) {
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if (value.is_cell())
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roots.set(value.as_cell());
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}
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}
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#if HEAP_DEBUG
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dbgln("gather_roots:");
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for (auto* root : roots)
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dbgln(" + {}", root);
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#endif
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}
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__attribute__((no_sanitize("address"))) void Heap::gather_conservative_roots(HashTable<Cell*>& roots)
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{
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FlatPtr dummy;
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#if HEAP_DEBUG
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dbgln("gather_conservative_roots:");
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#endif
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jmp_buf buf;
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setjmp(buf);
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HashTable<FlatPtr> possible_pointers;
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const FlatPtr* raw_jmp_buf = reinterpret_cast<const FlatPtr*>(buf);
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for (size_t i = 0; i < ((size_t)sizeof(buf)) / sizeof(FlatPtr); i += sizeof(FlatPtr))
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possible_pointers.set(raw_jmp_buf[i]);
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FlatPtr stack_reference = reinterpret_cast<FlatPtr>(&dummy);
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auto& stack_info = m_vm.stack_info();
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for (FlatPtr stack_address = stack_reference; stack_address < stack_info.top(); stack_address += sizeof(FlatPtr)) {
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auto data = *reinterpret_cast<FlatPtr*>(stack_address);
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possible_pointers.set(data);
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}
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HashTable<HeapBlock*> all_live_heap_blocks;
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for_each_block([&](auto& block) {
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all_live_heap_blocks.set(&block);
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return IterationDecision::Continue;
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});
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for (auto possible_pointer : possible_pointers) {
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if (!possible_pointer)
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continue;
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#if HEAP_DEBUG
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dbgln(" ? {}", (const void*)possible_pointer);
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#endif
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auto* possible_heap_block = HeapBlock::from_cell(reinterpret_cast<const Cell*>(possible_pointer));
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if (all_live_heap_blocks.contains(possible_heap_block)) {
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if (auto* cell = possible_heap_block->cell_from_possible_pointer(possible_pointer)) {
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if (cell->is_live()) {
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#if HEAP_DEBUG
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dbgln(" ?-> {}", (const void*)cell);
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#endif
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roots.set(cell);
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} else {
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#if HEAP_DEBUG
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dbgln(" #-> {}", (const void*)cell);
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#endif
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}
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}
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}
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}
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}
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class MarkingVisitor final : public Cell::Visitor {
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public:
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MarkingVisitor() { }
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virtual void visit_impl(Cell* cell)
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{
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if (cell->is_marked())
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return;
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#if HEAP_DEBUG
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dbgln(" ! {}", cell);
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#endif
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cell->set_marked(true);
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cell->visit_edges(*this);
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}
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};
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void Heap::mark_live_cells(const HashTable<Cell*>& roots)
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{
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#if HEAP_DEBUG
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dbgln("mark_live_cells:");
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#endif
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MarkingVisitor visitor;
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for (auto* root : roots)
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visitor.visit(root);
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}
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void Heap::sweep_dead_cells(bool print_report, const Core::ElapsedTimer& measurement_timer)
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{
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#if HEAP_DEBUG
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dbgln("sweep_dead_cells:");
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#endif
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Vector<HeapBlock*, 32> empty_blocks;
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Vector<HeapBlock*, 32> full_blocks_that_became_usable;
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size_t collected_cells = 0;
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size_t live_cells = 0;
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size_t collected_cell_bytes = 0;
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size_t live_cell_bytes = 0;
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for_each_block([&](auto& block) {
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bool block_has_live_cells = false;
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bool block_was_full = block.is_full();
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block.for_each_cell([&](Cell* cell) {
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if (cell->is_live()) {
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if (!cell->is_marked()) {
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#if HEAP_DEBUG
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dbgln(" ~ {}", cell);
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#endif
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block.deallocate(cell);
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++collected_cells;
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collected_cell_bytes += block.cell_size();
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} else {
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cell->set_marked(false);
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block_has_live_cells = true;
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++live_cells;
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live_cell_bytes += block.cell_size();
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}
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}
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});
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if (!block_has_live_cells)
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empty_blocks.append(&block);
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else if (block_was_full != block.is_full())
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full_blocks_that_became_usable.append(&block);
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return IterationDecision::Continue;
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});
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for (auto* block : empty_blocks) {
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#if HEAP_DEBUG
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dbgln(" - HeapBlock empty @ {}: cell_size={}", block, block->cell_size());
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#endif
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allocator_for_size(block->cell_size()).block_did_become_empty({}, *block);
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}
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for (auto* block : full_blocks_that_became_usable) {
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#if HEAP_DEBUG
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dbgln(" - HeapBlock usable again @ {}: cell_size={}", block, block->cell_size());
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#endif
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allocator_for_size(block->cell_size()).block_did_become_usable({}, *block);
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}
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#if HEAP_DEBUG
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for_each_block([&](auto& block) {
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dbgln(" > Live HeapBlock @ {}: cell_size={}", &block, block.cell_size());
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return IterationDecision::Continue;
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});
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#endif
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int time_spent = measurement_timer.elapsed();
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if (print_report) {
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size_t live_block_count = 0;
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for_each_block([&](auto&) {
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++live_block_count;
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return IterationDecision::Continue;
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});
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dbgln("Garbage collection report");
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dbgln("=============================================");
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dbgln(" Time spent: {} ms", time_spent);
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dbgln(" Live cells: {} ({} bytes)", live_cells, live_cell_bytes);
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dbgln("Collected cells: {} ({} bytes)", collected_cells, collected_cell_bytes);
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dbgln(" Live blocks: {} ({} bytes)", live_block_count, live_block_count * HeapBlock::block_size);
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dbgln(" Freed blocks: {} ({} bytes)", empty_blocks.size(), empty_blocks.size() * HeapBlock::block_size);
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dbgln("=============================================");
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}
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}
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void Heap::did_create_handle(Badge<HandleImpl>, HandleImpl& impl)
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{
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VERIFY(!m_handles.contains(&impl));
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m_handles.set(&impl);
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}
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void Heap::did_destroy_handle(Badge<HandleImpl>, HandleImpl& impl)
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{
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VERIFY(m_handles.contains(&impl));
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m_handles.remove(&impl);
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}
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void Heap::did_create_marked_value_list(Badge<MarkedValueList>, MarkedValueList& list)
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{
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VERIFY(!m_marked_value_lists.contains(&list));
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m_marked_value_lists.set(&list);
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}
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void Heap::did_destroy_marked_value_list(Badge<MarkedValueList>, MarkedValueList& list)
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{
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VERIFY(m_marked_value_lists.contains(&list));
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m_marked_value_lists.remove(&list);
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}
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void Heap::defer_gc(Badge<DeferGC>)
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{
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++m_gc_deferrals;
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}
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void Heap::undefer_gc(Badge<DeferGC>)
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{
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VERIFY(m_gc_deferrals > 0);
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--m_gc_deferrals;
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if (!m_gc_deferrals) {
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if (m_should_gc_when_deferral_ends)
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collect_garbage();
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m_should_gc_when_deferral_ends = false;
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}
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}
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}
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