core/memory: Read and write page table atomically

Squash attributes into the pointer's integer, making them an uintptr_t
pair containing 2 bits at the bottom and then the pointer. These bits
are currently unused thanks to alignment requirements.

Configure Dynarmic to mask out these bits on pointer reads.

While we are at it, remove some unused attributes carried over from
Citra.

Read/Write and other hot functions use a two step unpacking process that
is less readable to stop MSVC from emitting an extra AND instruction in
the hot path:

 mov         rdi,rcx
 shr         rdx,0Ch
 mov         r8,qword ptr [rax+8]
 mov         rax,qword ptr [r8+rdx*8]
 mov         rdx,rax
-and         al,3
 and         rdx,0FFFFFFFFFFFFFFFCh
 je          Core::Memory::Memory::Impl::Read<unsigned char>
 mov         rax,qword ptr [vaddr]
 movzx       eax,byte ptr [rdx+rax]

1 files changed, 6 insertions, 4 deletions

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)} {