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AK: Allow inlining ref-count functionality

Browse source 
Previously we'd incur the costs for a function call via the PLT even
for the most trivial ref-count actions like increasing/decreasing the
reference count.

By moving the code to the header file we allow the compiler to inline
this code into the caller's function.
This commit is contained in:
Gunnar Beutner 2021-06-03 01:12:09 +02:00 committed by Andreas Kling
parent ab4f4ddc3c
commit ed0068d04d
3 changed files with 33 additions and 53 deletions
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47
AK/RefCounted.cpp
View file

@ -1,47 +0,0 @@
/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/RefCounted.h>
namespace AK {
RefCountedBase::~RefCountedBase()
{
VERIFY(m_ref_count.load(AK::MemoryOrder::memory_order_relaxed) == 0);
}
void RefCountedBase::ref() const
{
auto old_ref_count = m_ref_count.fetch_add(1, AK::MemoryOrder::memory_order_relaxed);
VERIFY(old_ref_count > 0);
VERIFY(!Checked<RefCountType>::addition_would_overflow(old_ref_count, 1));
}
[[nodiscard]] bool RefCountedBase::try_ref() const
{
RefCountType expected = m_ref_count.load(AK::MemoryOrder::memory_order_relaxed);
for (;;) {
if (expected == 0)
return false;
VERIFY(!Checked<RefCountType>::addition_would_overflow(expected, 1));
if (m_ref_count.compare_exchange_strong(expected, expected + 1, AK::MemoryOrder::memory_order_acquire))
return true;
}
}
RefCountedBase::RefCountType RefCountedBase::ref_count() const
{
return m_ref_count.load(AK::MemoryOrder::memory_order_relaxed);
}
RefCountedBase::RefCountType RefCountedBase::deref_base() const
{
auto old_ref_count = m_ref_count.fetch_sub(1, AK::MemoryOrder::memory_order_acq_rel);
VERIFY(old_ref_count > 0);
return old_ref_count - 1;
}
}

38
AK/RefCounted.h
View file

@ -47,15 +47,43 @@ public:
using RefCountType = unsigned int;
using AllowOwnPtr = FalseType;
void ref() const;
[[nodiscard]] bool try_ref() const;
[[nodiscard]] RefCountType ref_count() const;
void ref() const
{
auto old_ref_count = m_ref_count.fetch_add(1, AK::MemoryOrder::memory_order_relaxed);
VERIFY(old_ref_count > 0);
VERIFY(!Checked<RefCountType>::addition_would_overflow(old_ref_count, 1));
}
[[nodiscard]] bool try_ref() const
{
RefCountType expected = m_ref_count.load(AK::MemoryOrder::memory_order_relaxed);
for (;;) {
if (expected == 0)
return false;
VERIFY(!Checked<RefCountType>::addition_would_overflow(expected, 1));
if (m_ref_count.compare_exchange_strong(expected, expected + 1, AK::MemoryOrder::memory_order_acquire))
return true;
}
}
[[nodiscard]] RefCountType ref_count() const
{
return m_ref_count.load(AK::MemoryOrder::memory_order_relaxed);
}
protected:
RefCountedBase() = default;
~RefCountedBase();
~RefCountedBase()
{
VERIFY(m_ref_count.load(AK::MemoryOrder::memory_order_relaxed) == 0);
}
RefCountType deref_base() const;
RefCountType deref_base() const
{
auto old_ref_count = m_ref_count.fetch_sub(1, AK::MemoryOrder::memory_order_acq_rel);
VERIFY(old_ref_count > 0);
return old_ref_count - 1;
}
mutable Atomic<RefCountType> m_ref_count { 1 };
};

1
Kernel/CMakeLists.txt
View file

@ -277,7 +277,6 @@ set(AK_SOURCES
../AK/JsonParser.cpp
../AK/JsonValue.cpp
../AK/LexicalPath.cpp
../AK/RefCounted.cpp
../AK/String.cpp
../AK/StringBuilder.cpp
../AK/StringImpl.cpp