From 932945d4808e37ba0ca1a953571187f445e24f41 Mon Sep 17 00:00:00 2001
From: Shawn Hoffman <godisgovernment@gmail.com>
Date: Thu, 6 Mar 2014 14:38:10 -0800
Subject: [PATCH] Implement workaround for Windows versions which do not
 support XSAVE.

Fixes CRT math routines using FMA instructions from causing illegal instructions.
---
 Source/Core/Common/Common.vcxproj         |  1 +
 Source/Core/Common/Common.vcxproj.filters |  1 +
 Source/Core/Common/XSaveWorkaround.cpp    | 40 +++++++++++++++++++++++
 3 files changed, 42 insertions(+)
 create mode 100644 Source/Core/Common/XSaveWorkaround.cpp

diff --git a/Source/Core/Common/Common.vcxproj b/Source/Core/Common/Common.vcxproj
index 48cbcdfe3c..2aa69ba1b7 100644
--- a/Source/Core/Common/Common.vcxproj
+++ b/Source/Core/Common/Common.vcxproj
@@ -125,6 +125,7 @@
     <ClCompile Include="x64CPUDetect.cpp" />
     <ClCompile Include="x64Emitter.cpp" />
     <ClCompile Include="x64FPURoundMode.cpp" />
+    <ClCompile Include="XSaveWorkaround.cpp" />
   </ItemGroup>
   <ItemGroup>
     <Text Include="CMakeLists.txt" />
diff --git a/Source/Core/Common/Common.vcxproj.filters b/Source/Core/Common/Common.vcxproj.filters
index f2b194c007..d932b32be5 100644
--- a/Source/Core/Common/Common.vcxproj.filters
+++ b/Source/Core/Common/Common.vcxproj.filters
@@ -103,6 +103,7 @@
       <Filter>Logging</Filter>
     </ClCompile>
     <ClCompile Include="stdafx.cpp" />
+    <ClCompile Include="XSaveWorkaround.cpp" />
   </ItemGroup>
   <ItemGroup>
     <Text Include="CMakeLists.txt" />
diff --git a/Source/Core/Common/XSaveWorkaround.cpp b/Source/Core/Common/XSaveWorkaround.cpp
new file mode 100644
index 0000000000..30a2a42b2b
--- /dev/null
+++ b/Source/Core/Common/XSaveWorkaround.cpp
@@ -0,0 +1,40 @@
+// Copyright 2013 Dolphin Emulator Project
+// Licensed under GPLv2
+// Refer to the license.txt file included.
+
+#if defined(_WIN32) && defined(_ARCH_64)
+
+#include <math.h>
+#include <Windows.h>
+
+// This puts the rest of this translation unit into a segment which is
+// initialized by the CRT *before* any of the other code (including C++
+// static initializers).
+#pragma warning(disable : 4075)
+#pragma init_seg(".CRT$XCB")
+
+struct EnableXSaveWorkaround
+{
+	EnableXSaveWorkaround()
+	{
+		// Some Windows environments may have hardware support for AVX/FMA,
+		// but the OS does not support it. The CRT math library does not support
+		// this scenario, so we have to manually tell it not to use FMA3
+		// instructions.
+
+		// The API name is somewhat misleading - we're testing for OS support
+		// here.
+		if (!IsProcessorFeaturePresent(PF_XSAVE_ENABLED))
+		{
+			_set_FMA3_enable(0);
+		}
+	}
+};
+
+static EnableXSaveWorkaround enableXSaveWorkaround;
+
+// N.B. Any code after this will still be in the .CRT$XCB segment. Please just
+// do not append any code here unless it is intended to be executed before
+// static initializers.
+
+#endif