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SPU: Use CMPXCHG16B for atomic store if possible

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This commit is contained in:
Elad 2025-11-15 14:11:47 +02:00
parent 109abea454
commit 63f7bcf652
1 changed files with 45 additions and 2 deletions
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47
rpcs3/Emu/Cell/SPUThread.cpp
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@ -303,6 +303,33 @@ static FORCE_INLINE void mov_rdata_avx(__m256i* dst, const __m256i* src)
}
#endif
// Check if only a single 16-bytes block has changed
// Returning its position, or -1 if that is not the situation
static inline usz scan16_rdata(const decltype(spu_thread::rdata)& _lhs, const decltype(spu_thread::rdata)& _rhs)
{
const auto lhs = reinterpret_cast<const v128*>(_lhs);
const auto rhs = reinterpret_cast<const v128*>(_rhs);
u32 mask = 0;
for (usz i = 0; i < 8; i += 4)
{
const u32 a = (lhs[i + 0] != rhs[i + 0]) ? 1 : 0;
const u32 b = (lhs[i + 1] != rhs[i + 1]) ? 1 : 0;
const u32 c = (lhs[i + 2] != rhs[i + 2]) ? 1 : 0;
const u32 d = (lhs[i + 3] != rhs[i + 3]) ? 1 : 0;
mask |= ((a << 0) + (b << 1) + (c << 2) + (c << 3)) << i;
}
if (mask && (mask & (mask - 1)) == 0)
{
return std::countr_zero(mask);
}
return umax;
}
#ifdef _MSC_VER
__forceinline
#endif
@ -3854,6 +3881,11 @@ bool spu_thread::do_putllc(const spu_mfc_cmd& args)
return false;
}
static const auto cast_as = [](void* ptr, usz pos){ return reinterpret_cast<u128*>(ptr) + pos; };
static const auto cast_as_const = [](const void* ptr, usz pos){ return reinterpret_cast<const u128*>(ptr) + pos; };
const usz diff16_pos = scan16_rdata(to_write, rdata);
auto [_oldd, _ok] = res.fetch_op([&](u64& r)
{
if ((r & -128) != rtime || (r & 127))
@ -3975,8 +4007,19 @@ bool spu_thread::do_putllc(const spu_mfc_cmd& args)
if (cmp_rdata(rdata, super_data))
{
mov_rdata(super_data, to_write);
return true;
if (diff16_pos != umax)
{
// Do it with CMPXCHG16B if possible, this allows to improve accuracy whenever "RSX Accurate Reservations" is off
if (atomic_storage<u128>::compare_exchange(*cast_as(super_data, diff16_pos), *cast_as(rdata, diff16_pos), *cast_as_const(to_write, diff16_pos)))
{
return true;
}
}
else
{
mov_rdata(super_data, to_write);
return true;
}
}
return false;