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Fat atomics: implement exchange() and compare_exchange()

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Also includes compare_and_swap() and compare_and_swap_test().
Also includes fixes for load(), store(), and atomic_op().
This commit is contained in:
Nekotekina 2020-04-10 16:57:15 +03:00
parent cb14805d78
commit 17f3a114be
1 changed files with 53 additions and 2 deletions
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55
rpcs3/util/atomic.hpp
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@ -1176,7 +1176,6 @@ class atomic_with_lock_bit
static_assert(std::is_pointer_v<T> == (BitWidth == 0), "BitWidth should be 0 for pointers");
static_assert(!std::is_pointer_v<T> || (alignof(std::remove_pointer_t<T>) >= 4), "Pointer type should have align 4 or more");
// Use the most significant bit as a mutex
atomic_t<type> m_data;
public:
@ -1255,7 +1254,6 @@ public:
// Try to set dirty bit if not set already
if (!m_data.compare_and_swap_test(old_val, old_val | c_dirty))
{
// Situation changed
continue;
}
}
@ -1301,6 +1299,7 @@ public:
{
if (!m_data.compare_and_swap_test(old_val, old_val | c_dirty))
{
old_val = m_data.load();
continue;
}
}
@ -1313,6 +1312,11 @@ public:
}
void store(T value)
{
static_cast<void>(exchange(value));
}
T exchange(T value)
{
type old_val = m_data.load();
@ -1322,6 +1326,7 @@ public:
{
if (!m_data.compare_and_swap_test(old_val, old_val | c_dirty))
{
old_val = m_data.load();
continue;
}
}
@ -1329,6 +1334,51 @@ public:
m_data.wait(old_val);
old_val = m_data.load();
}
return reinterpret_cast<T>(clamp_value(old_val));
}
T compare_and_swap(T cmp, T exch)
{
static_cast<void>(compare_exchange(cmp, exch));
return cmp;
}
bool compare_and_swap_test(T cmp, T exch)
{
return compare_exchange(cmp, exch);
}
bool compare_exchange(T& cmp_and_old, T exch)
{
type old_val = m_data.load();
type expected = clamp_value(reinterpret_cast<type>(cmp_and_old));
type new_val = clamp_value(reinterpret_cast<type>(exch));
while (is_locked(old_val) || (old_val == expected && !m_data.compare_and_swap_test(expected, new_val))) [[unlikely]]
{
if (old_val == expected)
{
old_val = m_data.load();
continue;
}
if ((old_val & c_dirty) == 0)
{
if (!m_data.compare_and_swap_test(old_val, old_val | c_dirty))
{
old_val = m_data.load();
continue;
}
}
m_data.wait(old_val);
old_val = m_data.load();
}
cmp_and_old = reinterpret_cast<T>(clamp_value(old_val));
return clamp_value(old_val) == expected;
}
template <typename F, typename RT = std::invoke_result_t<F, T&>>
@ -1345,6 +1395,7 @@ public:
{
if (!m_data.compare_and_swap_test(old, old | c_dirty))
{
old = m_data.load();
continue;
}
}