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// 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
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