forked from dolphin-emu/dolphin
62 lines
1.8 KiB
C++
62 lines
1.8 KiB
C++
// Copyright 2014 Dolphin Emulator Project
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// Licensed under GPLv2+
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// Refer to the license.txt file included.
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#if defined(_WIN32)
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#include <math.h>
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#include <Windows.h>
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typedef decltype(&GetEnabledXStateFeatures) GetEnabledXStateFeatures_t;
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int __cdecl EnableXSaveWorkaround()
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{
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// Some Windows environments may have hardware support for AVX/FMA,
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// but the OS does not support it. The CRT math library does not support
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// this scenario, so we have to manually tell it not to use FMA3
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// instructions.
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// The API name is somewhat misleading - we're testing for OS support
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// here.
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if (!IsProcessorFeaturePresent(PF_XSAVE_ENABLED))
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{
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_set_FMA3_enable(0);
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return 0;
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}
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// Even if XSAVE feature is enabled, we have to see if
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// GetEnabledXStateFeatures function is present, and see what it says about
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// AVX state.
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auto kernel32Handle = GetModuleHandle(TEXT("kernel32.dll"));
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if (kernel32Handle == nullptr)
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{
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std::abort();
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}
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auto pGetEnabledXStateFeatures = (GetEnabledXStateFeatures_t)GetProcAddress(
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kernel32Handle, "GetEnabledXStateFeatures");
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if (pGetEnabledXStateFeatures == nullptr ||
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(pGetEnabledXStateFeatures() & XSTATE_MASK_AVX) == 0)
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{
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_set_FMA3_enable(0);
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}
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return 0;
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}
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// Create a segment which is recognized by the linker to be part of the CRT
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// initialization. XI* = C startup, XC* = C++ startup. "A" placement is reserved
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// for system use. Thus, the earliest we can get is XIB (C startup is before
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// C++).
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#pragma section(".CRT$XIB", read)
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// Place a symbol in the special segment, make it have C linkage so that
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// referencing it doesn't require ugly decorated names.
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// Use /include:XSaveWorkaround linker flag to enable this.
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extern "C" {
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__declspec(allocate(".CRT$XIB"))
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decltype(&EnableXSaveWorkaround) XSaveWorkaround = EnableXSaveWorkaround;
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};
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#endif
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