Remove Atomic.h

The STL has everything we need nowadays. I have tried to not alter any behavior or semantics with this change wherever possible. In particular, WriteLow and WriteHigh in CommandProcessor retain the ability to accidentally undo another thread's write to the upper half or lower half respectively. If that should be fixed, it should be done in a separate commit for clarity. One thing did change: The places where we were using += on a volatile variable (not an atomic operation) are now using fetch_add (actually an atomic operation). Tested with single core and dual core on x86-64 and AArch64.
dolphin-emu · May 13, 2021 · b93983b · b93983b
1 parent 80ac36a
commit b93983b
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Showing 13 changed files with 178 additions and 319 deletions.
diff --git a/Source/Core/Common/Atomic.h b/Source/Core/Common/Atomic.h
diff --git a/Source/Core/Common/Atomic_GCC.h b/Source/Core/Common/Atomic_GCC.h
diff --git a/Source/Core/Common/Atomic_Win32.h b/Source/Core/Common/Atomic_Win32.h
diff --git a/Source/Core/Common/CMakeLists.txt b/Source/Core/Common/CMakeLists.txt
@@ -2,7 +2,6 @@ add_library(common
   Analytics.cpp
   Analytics.h
   Assert.h
-  Atomic.h
   BitField.h
   BitSet.h
   BitUtils.h

diff --git a/Source/Core/Common/ChunkFile.h b/Source/Core/Common/ChunkFile.h
@@ -221,10 +221,10 @@ class PointerWrap
   template <typename T>
   void Do(std::atomic<T>& atomic)
   {
-    T temp = atomic.load();
+    T temp = atomic.load(std::memory_order_relaxed);
     Do(temp);
     if (mode == MODE_READ)
-      atomic.store(temp);
+      atomic.store(temp, std::memory_order_relaxed);
   }
 
   template <typename T>

diff --git a/Source/Core/Core/HW/MMIO.h b/Source/Core/Core/HW/MMIO.h
@@ -5,11 +5,13 @@
 #pragma once
 
 #include <array>
+#include <atomic>
 #include <string>
 #include <tuple>
 #include <type_traits>
 
 #include "Common/Assert.h"
+#include "Common/BitUtils.h"
 #include "Common/CommonTypes.h"
 #include "Core/ConfigManager.h"
 #include "Core/HW/MMIOHandlers.h"
@@ -79,17 +81,19 @@ inline u16* LowPart(u32* ptr)
 {
   return (u16*)ptr;
 }
-inline u16* LowPart(volatile u32* ptr)
+inline u16* LowPart(std::atomic<u32>* ptr)
 {
-  return (u16*)ptr;
+  static_assert(std::atomic<u32>::is_always_lock_free && sizeof(std::atomic<u32>) == sizeof(u32));
+  return LowPart(Common::BitCast<u32*>(ptr));
 }
 inline u16* HighPart(u32* ptr)
 {
   return LowPart(ptr) + 1;
 }
-inline u16* HighPart(volatile u32* ptr)
+inline u16* HighPart(std::atomic<u32>* ptr)
 {
-  return LowPart(ptr) + 1;
+  static_assert(std::atomic<u32>::is_always_lock_free && sizeof(std::atomic<u32>) == sizeof(u32));
+  return HighPart(Common::BitCast<u32*>(ptr));
 }
 }  // namespace Utils
 

diff --git a/Source/Core/Core/HW/SystemTimers.cpp b/Source/Core/Core/HW/SystemTimers.cpp
@@ -49,7 +49,6 @@ IPC_HLE_PERIOD: For the Wii Remote this is the call schedule:
 #include <cmath>
 #include <cstdlib>
 
-#include "Common/Atomic.h"
 #include "Common/CommonTypes.h"
 #include "Common/Logging/Log.h"
 #include "Common/Thread.h"

diff --git a/Source/Core/DolphinLib.props b/Source/Core/DolphinLib.props
@@ -16,9 +16,6 @@
     <ClInclude Include="Common\Align.h" />
     <ClInclude Include="Common\Analytics.h" />
     <ClInclude Include="Common\Assert.h" />
-    <ClInclude Include="Common\Atomic_GCC.h" />
-    <ClInclude Include="Common\Atomic_Win32.h" />
-    <ClInclude Include="Common\Atomic.h" />
     <ClInclude Include="Common\BitField.h" />
     <ClInclude Include="Common\BitSet.h" />
     <ClInclude Include="Common\BitUtils.h" />

diff --git a/Source/Core/VideoBackends/OGL/OGLRender.cpp b/Source/Core/VideoBackends/OGL/OGLRender.cpp
@@ -11,7 +11,6 @@
 #include <memory>
 #include <string>
 
-#include "Common/Atomic.h"
 #include "Common/CommonTypes.h"
 #include "Common/GL/GLContext.h"
 #include "Common/GL/GLUtil.h"