Merge branch 'master' into stable

1 files changed, 61 insertions, 0 deletions

diff --git a/Source/Core/Common/XSaveWorkaround.cpp b/Source/Core/Common/XSaveWorkaround.cpp
new file mode 100644
index 0000000000..a91af47a39
--- /dev/null
+++ b/Source/Core/Common/XSaveWorkaround.cpp
@@ -0,0 +1,61 @@
+// Copyright 2014 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#if defined(_WIN32)
+
+#include <math.h>
+#include <Windows.h>
+
+typedef decltype(&GetEnabledXStateFeatures) GetEnabledXStateFeatures_t;
+
+int __cdecl 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);
+		return 0;
+	}
+
+	// Even if XSAVE feature is enabled, we have to see if
+	// GetEnabledXStateFeatures function is present, and see what it says about
+	// AVX state.
+	auto kernel32Handle = GetModuleHandle(TEXT("kernel32.dll"));
+	if (kernel32Handle == nullptr)
+	{
+		std::abort();
+	}
+
+	auto pGetEnabledXStateFeatures = (GetEnabledXStateFeatures_t)GetProcAddress(
+		kernel32Handle, "GetEnabledXStateFeatures");
+	if (pGetEnabledXStateFeatures == nullptr ||
+		(pGetEnabledXStateFeatures() & XSTATE_MASK_AVX) == 0)
+	{
+		_set_FMA3_enable(0);
+	}
+
+	return 0;
+}
+
+// Create a segment which is recognized by the linker to be part of the CRT
+// initialization. XI* = C startup, XC* = C++ startup. "A" placement is reserved
+// for system use. Thus, the earliest we can get is XIB (C startup is before
+// C++).
+#pragma section(".CRT$XIB", read)
+
+// Place a symbol in the special segment, make it have C linkage so that
+// referencing it doesn't require ugly decorated names.
+// Use /include:XSaveWorkaround linker flag to enable this.
+extern "C" {
+	__declspec(allocate(".CRT$XIB"))
+	decltype(&EnableXSaveWorkaround) XSaveWorkaround = EnableXSaveWorkaround;
+};
+
+#endif