dolphin/Source/Core/Common/x64CPUDetect.cpp

// Copyright 2013 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <cstring>
#include <string>

#include "Common/CommonTypes.h"
#include "Common/CPUDetect.h"
#include "Common/Intrinsics.h"

#ifndef _WIN32

#ifdef __FreeBSD__
#include <sys/types.h>
#include <machine/cpufunc.h>
#endif

static inline void __cpuidex(int info[4], int function_id, int subfunction_id)
{
#ifdef __FreeBSD__
	// Despite the name, this is just do_cpuid() with ECX as second input.
	cpuid_count((u_int)function_id, (u_int)subfunction_id, (u_int*)info);
#else
	info[0] = function_id;    // eax
	info[2] = subfunction_id; // ecx
	__asm__(
		"cpuid"
		: "=a" (info[0]),
		  "=b" (info[1]),
		  "=c" (info[2]),
		  "=d" (info[3])
		: "a" (function_id),
		  "c" (subfunction_id)
	);
#endif
}

static inline void __cpuid(int info[4], int function_id)
{
	return __cpuidex(info, function_id, 0);
}

#define _XCR_XFEATURE_ENABLED_MASK 0
static u64 _xgetbv(u32 index)
{
	u32 eax, edx;
	__asm__ __volatile__("xgetbv" : "=a"(eax), "=d"(edx) : "c"(index));
	return ((u64)edx << 32) | eax;
}

#endif // ifndef _WIN32

CPUInfo cpu_info;

CPUInfo::CPUInfo()
{
	Detect();
}

// Detects the various CPU features
void CPUInfo::Detect()
{
	memset(this, 0, sizeof(*this));
#ifdef _M_X86_64
	Mode64bit = true;
	OS64bit = true;
#endif
	num_cores = 1;

	// Set obvious defaults, for extra safety
	if (Mode64bit)
	{
		bSSE = true;
		bSSE2 = true;
		bLongMode = true;
	}

	// Assume CPU supports the CPUID instruction. Those that don't can barely
	// boot modern OS:es anyway.
	int cpu_id[4];
	memset(brand_string, 0, sizeof(brand_string));

	// Detect CPU's CPUID capabilities, and grab CPU string
	__cpuid(cpu_id, 0x00000000);
	u32 max_std_fn = cpu_id[0];  // EAX
	*((int *)brand_string) = cpu_id[1];
	*((int *)(brand_string + 4)) = cpu_id[3];
	*((int *)(brand_string + 8)) = cpu_id[2];
	__cpuid(cpu_id, 0x80000000);
	u32 max_ex_fn = cpu_id[0];
	if (!strcmp(brand_string, "GenuineIntel"))
		vendor = VENDOR_INTEL;
	else if (!strcmp(brand_string, "AuthenticAMD"))
		vendor = VENDOR_AMD;
	else
		vendor = VENDOR_OTHER;

	// Set reasonable default brand string even if brand string not available.
	strcpy(cpu_string, brand_string);

	// Detect family and other misc stuff.
	bool ht = false;
	HTT = ht;
	logical_cpu_count = 1;
	if (max_std_fn >= 1)
	{
		__cpuid(cpu_id, 0x00000001);
		int family = ((cpu_id[0] >> 8) & 0xf) + ((cpu_id[0] >> 20) & 0xff);
		int model = ((cpu_id[0] >> 4) & 0xf) + ((cpu_id[0] >> 12) & 0xf0);
		// Detect people unfortunate enough to be running Dolphin on an Atom
		if (family == 6 && (model == 0x1C || model == 0x26 ||model == 0x27 || model == 0x35 || model == 0x36 ||
		                    model == 0x37 || model == 0x4A || model == 0x4D || model == 0x5A || model == 0x5D))
			bAtom = true;
		logical_cpu_count = (cpu_id[1] >> 16) & 0xFF;
		ht = (cpu_id[3] >> 28) & 1;

		if ((cpu_id[3] >> 25) & 1) bSSE = true;
		if ((cpu_id[3] >> 26) & 1) bSSE2 = true;
		if ((cpu_id[2])       & 1) bSSE3 = true;
		if ((cpu_id[2] >> 9)  & 1) bSSSE3 = true;
		if ((cpu_id[2] >> 19) & 1) bSSE4_1 = true;
		if ((cpu_id[2] >> 20) & 1) bSSE4_2 = true;
		if ((cpu_id[2] >> 22) & 1) bMOVBE = true;
		if ((cpu_id[2] >> 25) & 1) bAES = true;

		if ((cpu_id[3] >> 24) & 1)
		{
			// We can use FXSAVE.
			bFXSR = true;
		}

		// AVX support requires 3 separate checks:
		//  - Is the AVX bit set in CPUID?
		//  - Is the XSAVE bit set in CPUID?
		//  - XGETBV result has the XCR bit set.
		if (((cpu_id[2] >> 28) & 1) && ((cpu_id[2] >> 27) & 1))
		{
			if ((_xgetbv(_XCR_XFEATURE_ENABLED_MASK) & 0x6) == 0x6)
			{
				bAVX = true;
				if ((cpu_id[2] >> 12) & 1)
					bFMA = true;
			}
		}

		if (max_std_fn >= 7)
		{
			__cpuidex(cpu_id, 0x00000007, 0x00000000);
			// careful; we can't enable AVX2 unless the XSAVE/XGETBV checks above passed
			if ((cpu_id[1] >> 5) & 1)
				bAVX2 = bAVX;
			if ((cpu_id[1] >> 3) & 1)
				bBMI1 = true;
			if ((cpu_id[1] >> 8) & 1)
				bBMI2 = true;
		}
	}

	bFlushToZero = bSSE;

	if (max_ex_fn >= 0x80000004)
	{
		// Extract CPU model string
		__cpuid(cpu_id, 0x80000002);
		memcpy(cpu_string, cpu_id, sizeof(cpu_id));
		__cpuid(cpu_id, 0x80000003);
		memcpy(cpu_string + 16, cpu_id, sizeof(cpu_id));
		__cpuid(cpu_id, 0x80000004);
		memcpy(cpu_string + 32, cpu_id, sizeof(cpu_id));
	}
	if (max_ex_fn >= 0x80000001)
	{
		// Check for more features.
		__cpuid(cpu_id, 0x80000001);
		if (cpu_id[2] & 1) bLAHFSAHF64 = true;
		if ((cpu_id[2] >> 5) & 1) bLZCNT = true;
		if ((cpu_id[3] >> 29) & 1) bLongMode = true;
	}

	num_cores = (logical_cpu_count == 0) ? 1 : logical_cpu_count;

	if (max_ex_fn >= 0x80000008)
	{
		// Get number of cores. This is a bit complicated. Following AMD manual here.
		__cpuid(cpu_id, 0x80000008);
		int apic_id_core_id_size = (cpu_id[2] >> 12) & 0xF;
		if (apic_id_core_id_size == 0)
		{
			if (ht)
			{
				// New mechanism for modern Intel CPUs.
				if (vendor == VENDOR_INTEL)
				{
					__cpuidex(cpu_id, 0x00000004, 0x00000000);
					int cores_x_package = ((cpu_id[0] >> 26) & 0x3F) + 1;
					HTT = (cores_x_package < logical_cpu_count);
					cores_x_package = ((logical_cpu_count % cores_x_package) == 0) ? cores_x_package : 1;
					num_cores = (cores_x_package > 1) ? cores_x_package : num_cores;
					logical_cpu_count /= cores_x_package;
				}
			}
		}
		else
		{
			// Use AMD's new method.
			num_cores = (cpu_id[2] & 0xFF) + 1;
		}
	}
}

// Turn the CPU info into a string we can show
std::string CPUInfo::Summarize()
{
	std::string sum(cpu_string);
	sum += " (";
	sum += brand_string;
	sum += ")";

	if (bSSE) sum += ", SSE";
	if (bSSE2)
	{
		sum += ", SSE2";
		if (!bFlushToZero)
			sum += " (but not DAZ!)";
	}
	if (bSSE3) sum += ", SSE3";
	if (bSSSE3) sum += ", SSSE3";
	if (bSSE4_1) sum += ", SSE4.1";
	if (bSSE4_2) sum += ", SSE4.2";
	if (HTT) sum += ", HTT";
	if (bAVX) sum += ", AVX";
	if (bAVX2) sum += ", AVX2";
	if (bBMI1) sum += ", BMI1";
	if (bBMI2) sum += ", BMI2";
	if (bFMA) sum += ", FMA";
	if (bAES) sum += ", AES";
	if (bMOVBE) sum += ", MOVBE";
	if (bLongMode) sum += ", 64-bit support";
	return sum;
}