mirror of
https://github.com/LadybirdBrowser/ladybird
synced 2026-04-25 17:25:08 +02:00
0c5e4ebc18
Add a managed bump allocator backed by an 8 MB mmap region to replace alloca-based execution context allocation. Pages are committed on demand by the OS, so only the memory actually touched is resident. The InterpreterStack is stored as a member of VM and provides simple LIFO allocation and deallocation of ExecutionContext frames.
68 lines
1.7 KiB
C++
68 lines
1.7 KiB
C++
/*
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* Copyright (c) 2026, the Ladybird developers.
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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/Noncopyable.h>
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#include <AK/Platform.h>
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#include <AK/Types.h>
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#include <LibJS/Runtime/ExecutionContext.h>
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namespace JS {
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class InterpreterStack {
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AK_MAKE_NONCOPYABLE(InterpreterStack);
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AK_MAKE_NONMOVABLE(InterpreterStack);
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public:
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static constexpr size_t stack_size = 8 * MiB;
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InterpreterStack();
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~InterpreterStack();
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[[nodiscard]] ALWAYS_INLINE void* top() const { return m_top; }
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[[nodiscard]] ALWAYS_INLINE ExecutionContext* allocate(u32 registers_and_locals_count, u32 constants_count, u32 arguments_count)
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{
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auto tail_count = registers_and_locals_count + constants_count + arguments_count;
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auto size = sizeof(ExecutionContext) + tail_count * sizeof(Value);
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// Align up to alignof(ExecutionContext).
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size = (size + alignof(ExecutionContext) - 1) & ~(alignof(ExecutionContext) - 1);
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auto* new_top = static_cast<u8*>(m_top) + size;
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if (new_top > m_limit) [[unlikely]]
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return nullptr;
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auto* result = new (m_top) ExecutionContext(registers_and_locals_count, constants_count, arguments_count);
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m_top = new_top;
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return result;
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}
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ALWAYS_INLINE void deallocate(void* mark)
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{
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VERIFY(mark >= m_base && mark <= m_top);
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m_top = mark;
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}
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[[nodiscard]] ALWAYS_INLINE bool is_exhausted() const
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{
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return m_top >= m_limit;
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}
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[[nodiscard]] ALWAYS_INLINE size_t size_remaining() const
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{
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return static_cast<u8*>(m_limit) - static_cast<u8*>(m_top);
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}
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private:
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void* m_base { nullptr };
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void* m_top { nullptr };
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void* m_limit { nullptr };
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};
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}
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