From 4a883ba6eab66c3e4a123f805a388506b463cd36 Mon Sep 17 00:00:00 2001
From: Nekotekina <nekotekina@gmail.com>
Date: Tue, 15 Dec 2020 11:19:41 +0300
Subject: [PATCH] atomic.hpp: use SFINAE for waitable atomic detection

Add default_mask<> variable.
Refactor get_value<>().
---
 rpcs3/util/atomic.hpp | 109 ++++++++++++++++++++++--------------------
 1 file changed, 58 insertions(+), 51 deletions(-)

diff --git a/rpcs3/util/atomic.hpp b/rpcs3/util/atomic.hpp
index 2c10195a92..00d0cccfcf 100644
--- a/rpcs3/util/atomic.hpp
+++ b/rpcs3/util/atomic.hpp
@@ -114,6 +114,36 @@ namespace atomic_wait
 
 	constexpr op op_ne = op::eq | op_flag::inverse;
 
+	constexpr struct any_value_t
+	{
+		template <typename T>
+		operator T() const noexcept
+		{
+			return T();
+		}
+	} any_value;
+
+	template <typename X, typename T = decltype(std::declval<X>().observe())>
+	inline __m128i default_mask = sizeof(T) <= 8
+		? _mm_cvtsi64_si128(UINT64_MAX >> ((64 - sizeof(T) * 8) & 63))
+		: _mm_set1_epi64x(-1);
+
+	template <typename X, typename T = decltype(std::declval<X>().observe())>
+	constexpr __m128i get_value(X&, T value = T{}, ...)
+	{
+		static_assert((sizeof(T) & (sizeof(T) - 1)) == 0);
+		static_assert(sizeof(T) <= 16);
+
+		if constexpr (sizeof(T) <= 8)
+		{
+			return _mm_cvtsi64_si128(std::bit_cast<get_uint_t<sizeof(T)>, T>(value));
+		}
+		else if constexpr (sizeof(T) == 16)
+		{
+			return std::bit_cast<__m128i>(value);
+		}
+	}
+
 	struct info
 	{
 		const void* data;
@@ -121,29 +151,13 @@ namespace atomic_wait
 		__m128i old;
 		__m128i mask;
 
-		template <typename T>
-		static constexpr __m128i get_value(T value = T{})
+		template <typename X, typename T = decltype(std::declval<X>().observe())>
+		constexpr void set_value(X& a, T value = T{})
 		{
-			static_assert((sizeof(T) & (sizeof(T) - 1)) == 0);
-			static_assert(sizeof(T) <= 16);
-
-			if constexpr (sizeof(T) <= 8)
-			{
-				return _mm_cvtsi64_si128(std::bit_cast<get_uint_t<sizeof(T)>, T>(value));
-			}
-			else if constexpr (sizeof(T) == 16)
-			{
-				return std::bit_cast<__m128i>(value);
-			}
+			old = get_value(a, value);
 		}
 
-		template <typename T>
-		constexpr void set_value(T value = T{})
-		{
-			old = get_value<T>(value);
-		}
-
-		template <typename T>
+		template <typename X, typename T = decltype(std::declval<X>().observe())>
 		constexpr void set_mask(T value)
 		{
 			static_assert((sizeof(T) & (sizeof(T) - 1)) == 0);
@@ -159,23 +173,10 @@ namespace atomic_wait
 			}
 		}
 
-		template <typename T>
+		template <typename X, typename T = decltype(std::declval<X>().observe())>
 		constexpr void set_mask()
 		{
-			mask = get_mask<T>();
-		}
-
-		template <typename T>
-		static constexpr __m128i get_mask()
-		{
-			if constexpr (sizeof(T) <= 8)
-			{
-				return _mm_cvtsi64_si128(UINT64_MAX >> ((64 - sizeof(T) * 8) & 63));
-			}
-			else
-			{
-				return _mm_set1_epi64x(-1);
-			}
+			mask = default_mask<X>;
 		}
 	};
 
@@ -194,9 +195,9 @@ namespace atomic_wait
 
 		constexpr list& operator=(const list&) noexcept = default;
 
-		template <typename... U, std::size_t... Align>
-		constexpr list(atomic_t<U, Align>&... vars)
-			: m_info{{&vars.raw(), sizeof(U), info::get_value<U>(), info::get_mask<U>()}...}
+		template <typename... U, typename = std::void_t<decltype(std::declval<U>().template wait<op::eq>(any_value))...>>
+		constexpr list(U&... vars)
+			: m_info{{&vars, sizeof(vars.observe()), get_value(vars), default_mask<U>}...}
 		{
 			static_assert(sizeof...(U) == Max, "Inconsistent amount of atomics.");
 		}
@@ -207,7 +208,7 @@ namespace atomic_wait
 			static_assert(sizeof...(U) == Max, "Inconsistent amount of values.");
 
 			auto* ptr = m_info;
-			((ptr++)->template set_value<T>(values), ...);
+			((ptr->template set_value<T>(*static_cast<T*>(ptr->data), values), ptr++), ...);
 			return *this;
 		}
 
@@ -221,25 +222,25 @@ namespace atomic_wait
 			return *this;
 		}
 
-		template <uint Index, op Flags = op::eq, typename T2, std::size_t Align, typename U>
-		constexpr void set(atomic_t<T2, Align>& var, U value)
+		template <uint Index, op Flags = op::eq, typename T2, typename U, typename = std::void_t<decltype(std::declval<T2>().template wait<op::eq>(any_value))>>
+		constexpr void set(T2& var, U value)
 		{
 			static_assert(Index < Max);
 
-			m_info[Index].data = &var.raw();
-			m_info[Index].size = sizeof(T2) | (static_cast<u8>(Flags) << 8);
-			m_info[Index].template set_value<T2>(value);
+			m_info[Index].data = &var;
+			m_info[Index].size = sizeof(var.observe()) | (static_cast<u8>(Flags) << 8);
+			m_info[Index].template set_value<T2>(var, value);
 			m_info[Index].template set_mask<T2>();
 		}
 
-		template <uint Index, op Flags = op::eq, typename T2, std::size_t Align, typename U, typename V>
-		constexpr void set(atomic_t<T2, Align>& var, U value, V mask)
+		template <uint Index, op Flags = op::eq, typename T2, typename U, typename V, typename = std::void_t<decltype(std::declval<T2>().template wait<op::eq>(any_value))>>
+		constexpr void set(T2& var, U value, V mask)
 		{
 			static_assert(Index < Max);
 
-			m_info[Index].data = &var.raw();
-			m_info[Index].size = sizeof(T2) | (static_cast<u8>(Flags) << 8);
-			m_info[Index].template set_value<T2>(value);
+			m_info[Index].data = &var;
+			m_info[Index].size = sizeof(var.observe()) | (static_cast<u8>(Flags) << 8);
+			m_info[Index].template set_value<T2>(var, value);
 			m_info[Index].template set_mask<T2>(mask);
 		}
 
@@ -253,8 +254,8 @@ namespace atomic_wait
 		}
 	};
 
-	template <typename... T, std::size_t... Align>
-	list(atomic_t<T, Align>&... vars) -> list<sizeof...(T), T...>;
+	template <typename... T, typename = std::void_t<decltype(std::declval<T>().template wait<op::eq>(any_value))...>>
+	list(T&... vars) -> list<sizeof...(T), T...>;
 
 	// RDTSC with adjustment for being unique
 	u64 get_unique_tsc();
@@ -1719,3 +1720,9 @@ public:
 		base::notify_all(1);
 	}
 };
+
+namespace atomic_wait
+{
+	template <std::size_t Align>
+	inline __m128i default_mask<atomic_t<bool, Align>> = _mm_cvtsi32_si128(1);
+}