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atomic.cpp: don't load actual memory on empty mask

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It's not an optimization. It just allows some tricks safely.
This commit is contained in:
Nekotekina 2020-11-11 23:59:09 +03:00
parent d391133524
commit ad013d59f4
1 changed files with 10 additions and 2 deletions
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12
rpcs3/util/atomic.cpp
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@ -66,8 +66,10 @@ ptr_cmp(const void* data, u32 _size, __m128i old128, __m128i mask128, atomic_wai
u64 old_value = _mm_cvtsi128_si64(old128);
u64 mask = _mm_cvtsi128_si64(mask128) & (UINT64_MAX >> ((64 - size * 8) & 63));
switch (size)
// Don't load memory on empty mask
switch (mask ? size : 0)
{
case 0: break;
case 1: new_value = reinterpret_cast<const atomic_t<u8>*>(data)->load(); break;
case 2: new_value = reinterpret_cast<const atomic_t<u16>*>(data)->load(); break;
case 4: new_value = reinterpret_cast<const atomic_t<u32>*>(data)->load(); break;
@ -169,10 +171,16 @@ ptr_cmp(const void* data, u32 _size, __m128i old128, __m128i mask128, atomic_wai
}
else if (size == 16 && (flag == op::eq || flag == (op::eq | op_flag::inverse)))
{
u128 new_value = atomic_storage<u128>::load(*reinterpret_cast<const u128*>(data));
u128 new_value = 0;
u128 old_value = std::bit_cast<u128>(old128);
u128 mask = std::bit_cast<u128>(mask128);
// Don't load memory on empty mask
if (mask) [[likely]]
{
new_value = atomic_storage<u128>::load(*reinterpret_cast<const u128*>(data));
}
// TODO
result = !((old_value ^ new_value) & mask);
}