11 files changed, 167 insertions, 109 deletions

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 943ff996e..2c2bd2ee8 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -135,8 +135,6 @@ add_library(common STATIC
     math_util.h
     memory_detect.cpp
     memory_detect.h
-    memory_hook.cpp
-    memory_hook.h
     microprofile.cpp
     microprofile.h
     microprofileui.h
@@ -162,6 +160,8 @@ add_library(common STATIC
     thread.cpp
     thread.h
     thread_queue_list.h
+    thread_worker.cpp
+    thread_worker.h
     threadsafe_queue.h
     time_zone.cpp
     time_zone.h
diff --git a/src/common/concepts.h b/src/common/concepts.h
index 5bef3ad67..aa08065a7 100644
--- a/src/common/concepts.h
+++ b/src/common/concepts.h
@@ -31,4 +31,8 @@ concept DerivedFrom = requires {
     std::is_convertible_v<const volatile Derived*, const volatile Base*>;
 };
 
+// TODO: Replace with std::convertible_to when libc++ implements it.
+template <typename From, typename To>
+concept ConvertibleTo = std::is_convertible_v<From, To>;
+
 } // namespace Common
diff --git a/src/common/div_ceil.h b/src/common/div_ceil.h
index 6b2c48f91..95e1489a9 100644
--- a/src/common/div_ceil.h
+++ b/src/common/div_ceil.h
@@ -11,16 +11,16 @@ namespace Common {
 
 /// Ceiled integer division.
 template <typename N, typename D>
-requires std::is_integral_v<N>&& std::is_unsigned_v<D>[[nodiscard]] constexpr auto DivCeil(
-    N number, D divisor) {
-    return (static_cast<D>(number) + divisor - 1) / divisor;
+requires std::is_integral_v<N>&& std::is_unsigned_v<D>[[nodiscard]] constexpr N DivCeil(N number,
+                                                                                        D divisor) {
+    return static_cast<N>((static_cast<D>(number) + divisor - 1) / divisor);
 }
 
 /// Ceiled integer division with logarithmic divisor in base 2
 template <typename N, typename D>
-requires std::is_integral_v<N>&& std::is_unsigned_v<D>[[nodiscard]] constexpr auto DivCeilLog2(
+requires std::is_integral_v<N>&& std::is_unsigned_v<D>[[nodiscard]] constexpr N DivCeilLog2(
     N value, D alignment_log2) {
-    return (static_cast<D>(value) + (D(1) << alignment_log2) - 1) >> alignment_log2;
+    return static_cast<N>((static_cast<D>(value) + (D(1) << alignment_log2) - 1) >> alignment_log2);
 }
 
 } // namespace Common
diff --git a/src/common/memory_hook.cpp b/src/common/memory_hook.cpp
deleted file mode 100644
index 3986986d6..000000000
--- a/src/common/memory_hook.cpp
+++ /dev/null
@@ -1,11 +0,0 @@
-// Copyright 2018 Citra Emulator Project
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#include "common/memory_hook.h"
-
-namespace Common {
-
-MemoryHook::~MemoryHook() = default;
-
-} // namespace Common
diff --git a/src/common/memory_hook.h b/src/common/memory_hook.h
deleted file mode 100644
index adaa4c2c5..000000000
--- a/src/common/memory_hook.h
+++ /dev/null
@@ -1,47 +0,0 @@
-// Copyright 2016 Citra Emulator Project
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#pragma once
-
-#include <memory>
-#include <optional>
-
-#include "common/common_types.h"
-
-namespace Common {
-
-/**
- * Memory hooks have two purposes:
- * 1. To allow reads and writes to a region of memory to be intercepted. This is used to implement
- *    texture forwarding and memory breakpoints for debugging.
- * 2. To allow for the implementation of MMIO devices.
- *
- * A hook may be mapped to multiple regions of memory.
- *
- * If a std::nullopt or false is returned from a function, the read/write request is passed through
- * to the underlying memory region.
- */
-class MemoryHook {
-public:
-    virtual ~MemoryHook();
-
-    virtual std::optional<bool> IsValidAddress(VAddr addr) = 0;
-
-    virtual std::optional<u8> Read8(VAddr addr) = 0;
-    virtual std::optional<u16> Read16(VAddr addr) = 0;
-    virtual std::optional<u32> Read32(VAddr addr) = 0;
-    virtual std::optional<u64> Read64(VAddr addr) = 0;
-
-    virtual bool ReadBlock(VAddr src_addr, void* dest_buffer, std::size_t size) = 0;
-
-    virtual bool Write8(VAddr addr, u8 data) = 0;
-    virtual bool Write16(VAddr addr, u16 data) = 0;
-    virtual bool Write32(VAddr addr, u32 data) = 0;
-    virtual bool Write64(VAddr addr, u64 data) = 0;
-
-    virtual bool WriteBlock(VAddr dest_addr, const void* src_buffer, std::size_t size) = 0;
-};
-
-using MemoryHookPointer = std::shared_ptr<MemoryHook>;
-} // namespace Common
diff --git a/src/common/page_table.cpp b/src/common/page_table.cpp
index bccea0894..8fd8620fd 100644
--- a/src/common/page_table.cpp
+++ b/src/common/page_table.cpp
@@ -10,16 +10,10 @@ PageTable::PageTable() = default;
 
 PageTable::~PageTable() noexcept = default;
 
-void PageTable::Resize(std::size_t address_space_width_in_bits, std::size_t page_size_in_bits,
-                       bool has_attribute) {
-    const std::size_t num_page_table_entries{1ULL
-                                             << (address_space_width_in_bits - page_size_in_bits)};
+void PageTable::Resize(size_t address_space_width_in_bits, size_t page_size_in_bits) {
+    const size_t num_page_table_entries{1ULL << (address_space_width_in_bits - page_size_in_bits)};
     pointers.resize(num_page_table_entries);
     backing_addr.resize(num_page_table_entries);
-
-    if (has_attribute) {
-        attributes.resize(num_page_table_entries);
-    }
 }
 
 } // namespace Common
diff --git a/src/common/page_table.h b/src/common/page_table.h
index 9754fabf9..61c5552e0 100644
--- a/src/common/page_table.h
+++ b/src/common/page_table.h
@@ -4,10 +4,10 @@
 
 #pragma once
 
+#include <atomic>
 #include <tuple>
 
 #include "common/common_types.h"
-#include "common/memory_hook.h"
 #include "common/virtual_buffer.h"
 
 namespace Common {
@@ -20,27 +20,6 @@ enum class PageType : u8 {
     /// Page is mapped to regular memory, but also needs to check for rasterizer cache flushing and
     /// invalidation
     RasterizerCachedMemory,
-    /// Page is mapped to a I/O region. Writing and reading to this page is handled by functions.
-    Special,
-    /// Page is allocated for use.
-    Allocated,
-};
-
-struct SpecialRegion {
-    enum class Type {
-        DebugHook,
-        IODevice,
-    } type;
-
-    MemoryHookPointer handler;
-
-    [[nodiscard]] bool operator<(const SpecialRegion& other) const {
-        return std::tie(type, handler) < std::tie(other.type, other.handler);
-    }
-
-    [[nodiscard]] bool operator==(const SpecialRegion& other) const {
-        return std::tie(type, handler) == std::tie(other.type, other.handler);
-    }
 };
 
 /**
@@ -48,6 +27,59 @@ struct SpecialRegion {
  * mimics the way a real CPU page table works.
  */
 struct PageTable {
+    /// Number of bits reserved for attribute tagging.
+    /// This can be at most the guaranteed alignment of the pointers in the page table.
+    static constexpr int ATTRIBUTE_BITS = 2;
+
+    /**
+     * Pair of host pointer and page type attribute.
+     * This uses the lower bits of a given pointer to store the attribute tag.
+     * Writing and reading the pointer attribute pair is guaranteed to be atomic for the same method
+     * call. In other words, they are guaranteed to be synchronized at all times.
+     */
+    class PageInfo {
+    public:
+        /// Returns the page pointer
+        [[nodiscard]] u8* Pointer() const noexcept {
+            return ExtractPointer(raw.load(std::memory_order_relaxed));
+        }
+
+        /// Returns the page type attribute
+        [[nodiscard]] PageType Type() const noexcept {
+            return ExtractType(raw.load(std::memory_order_relaxed));
+        }
+
+        /// Returns the page pointer and attribute pair, extracted from the same atomic read
+        [[nodiscard]] std::pair<u8*, PageType> PointerType() const noexcept {
+            const uintptr_t non_atomic_raw = raw.load(std::memory_order_relaxed);
+            return {ExtractPointer(non_atomic_raw), ExtractType(non_atomic_raw)};
+        }
+
+        /// Returns the raw representation of the page information.
+        /// Use ExtractPointer and ExtractType to unpack the value.
+        [[nodiscard]] uintptr_t Raw() const noexcept {
+            return raw.load(std::memory_order_relaxed);
+        }
+
+        /// Write a page pointer and type pair atomically
+        void Store(u8* pointer, PageType type) noexcept {
+            raw.store(reinterpret_cast<uintptr_t>(pointer) | static_cast<uintptr_t>(type));
+        }
+
+        /// Unpack a pointer from a page info raw representation
+        [[nodiscard]] static u8* ExtractPointer(uintptr_t raw) noexcept {
+            return reinterpret_cast<u8*>(raw & (~uintptr_t{0} << ATTRIBUTE_BITS));
+        }
+
+        /// Unpack a page type from a page info raw representation
+        [[nodiscard]] static PageType ExtractType(uintptr_t raw) noexcept {
+            return static_cast<PageType>(raw & ((uintptr_t{1} << ATTRIBUTE_BITS) - 1));
+        }
+
+    private:
+        std::atomic<uintptr_t> raw;
+    };
+
     PageTable();
     ~PageTable() noexcept;
 
@@ -58,25 +90,21 @@ struct PageTable {
     PageTable& operator=(PageTable&&) noexcept = default;
 
     /**
-     * Resizes the page table to be able to accomodate enough pages within
+     * Resizes the page table to be able to accommodate enough pages within
      * a given address space.
      *
      * @param address_space_width_in_bits The address size width in bits.
      * @param page_size_in_bits           The page size in bits.
-     * @param has_attribute               Whether or not this page has any backing attributes.
      */
-    void Resize(std::size_t address_space_width_in_bits, std::size_t page_size_in_bits,
-                bool has_attribute);
+    void Resize(size_t address_space_width_in_bits, size_t page_size_in_bits);
 
     /**
      * Vector of memory pointers backing each page. An entry can only be non-null if the
-     * corresponding entry in the `attributes` vector is of type `Memory`.
+     * corresponding attribute element is of type `Memory`.
      */
-    VirtualBuffer<u8*> pointers;
+    VirtualBuffer<PageInfo> pointers;
 
     VirtualBuffer<u64> backing_addr;
-
-    VirtualBuffer<PageType> attributes;
 };
 
 } // namespace Common
diff --git a/src/common/swap.h b/src/common/swap.h
index 7665942a2..a80e191dc 100644
--- a/src/common/swap.h
+++ b/src/common/swap.h
@@ -394,7 +394,7 @@ public:
     template <typename S, typename T2, typename F2>
     friend S operator%(const S& p, const swapped_t v);
 
-    // Arithmetics + assignements
+    // Arithmetics + assignments
     template <typename S, typename T2, typename F2>
     friend S operator+=(const S& p, const swapped_t v);
 
@@ -451,7 +451,7 @@ S operator%(const S& i, const swap_struct_t<T, F> v) {
     return i % v.swap();
 }
 
-// Arithmetics + assignements
+// Arithmetics + assignments
 template <typename S, typename T, typename F>
 S& operator+=(S& i, const swap_struct_t<T, F> v) {
     i += v.swap();
diff --git a/src/common/thread_worker.cpp b/src/common/thread_worker.cpp
new file mode 100644
index 000000000..8f9bf447a
--- /dev/null
+++ b/src/common/thread_worker.cpp
@@ -0,0 +1,58 @@
+// Copyright 2020 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/thread.h"
+#include "common/thread_worker.h"
+
+namespace Common {
+
+ThreadWorker::ThreadWorker(std::size_t num_workers, const std::string& name) {
+    for (std::size_t i = 0; i < num_workers; ++i)
+        threads.emplace_back([this, thread_name{std::string{name}}] {
+            Common::SetCurrentThreadName(thread_name.c_str());
+
+            // Wait for first request
+            {
+                std::unique_lock lock{queue_mutex};
+                condition.wait(lock, [this] { return stop || !requests.empty(); });
+            }
+
+            while (true) {
+                std::function<void()> task;
+
+                {
+                    std::unique_lock lock{queue_mutex};
+                    condition.wait(lock, [this] { return stop || !requests.empty(); });
+                    if (stop || requests.empty()) {
+                        return;
+                    }
+                    task = std::move(requests.front());
+                    requests.pop();
+                }
+
+                task();
+            }
+        });
+}
+
+ThreadWorker::~ThreadWorker() {
+    {
+        std::unique_lock lock{queue_mutex};
+        stop = true;
+    }
+    condition.notify_all();
+    for (std::thread& thread : threads) {
+        thread.join();
+    }
+}
+
+void ThreadWorker::QueueWork(std::function<void()>&& work) {
+    {
+        std::unique_lock lock{queue_mutex};
+        requests.emplace(work);
+    }
+    condition.notify_one();
+}
+
+} // namespace Common
diff --git a/src/common/thread_worker.h b/src/common/thread_worker.h
new file mode 100644
index 000000000..f1859971f
--- /dev/null
+++ b/src/common/thread_worker.h
@@ -0,0 +1,30 @@
+// Copyright 2020 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <atomic>
+#include <functional>
+#include <mutex>
+#include <string>
+#include <vector>
+#include <queue>
+
+namespace Common {
+
+class ThreadWorker final {
+public:
+    explicit ThreadWorker(std::size_t num_workers, const std::string& name);
+    ~ThreadWorker();
+    void QueueWork(std::function<void()>&& work);
+
+private:
+    std::vector<std::thread> threads;
+    std::queue<std::function<void()>> requests;
+    std::mutex queue_mutex;
+    std::condition_variable condition;
+    std::atomic_bool stop{};
+};
+
+} // namespace Common
diff --git a/src/common/virtual_buffer.h b/src/common/virtual_buffer.h
index 91d430036..fb1a6f81f 100644
--- a/src/common/virtual_buffer.h
+++ b/src/common/virtual_buffer.h
@@ -15,10 +15,12 @@ void FreeMemoryPages(void* base, std::size_t size) noexcept;
 template <typename T>
 class VirtualBuffer final {
 public:
-    static_assert(
-        std::is_trivially_constructible_v<T>,
-        "T must be trivially constructible, as non-trivial constructors will not be executed "
-        "with the current allocator");
+    // TODO: Uncomment this and change Common::PageTable::PageInfo to be trivially constructible
+    // using std::atomic_ref once libc++ has support for it
+    // static_assert(
+    //     std::is_trivially_constructible_v<T>,
+    //     "T must be trivially constructible, as non-trivial constructors will not be executed "
+    //     "with the current allocator");
 
     constexpr VirtualBuffer() = default;
     explicit VirtualBuffer(std::size_t count) : alloc_size{count * sizeof(T)} {