118 lines
3.4 KiB
C++
118 lines
3.4 KiB
C++
/*
|
|
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
// Parts of this file derived from Chromium's base/cpu.cc.
|
|
|
|
#include "rtc_base/system/arch.h"
|
|
#include "system_wrappers/include/cpu_features_wrapper.h"
|
|
|
|
#if defined(WEBRTC_ARCH_X86_FAMILY) && defined(_MSC_VER)
|
|
#include <intrin.h>
|
|
#endif
|
|
|
|
namespace webrtc {
|
|
|
|
// No CPU feature is available => straight C path.
|
|
int GetCPUInfoNoASM(CPUFeature feature) {
|
|
(void)feature;
|
|
return 0;
|
|
}
|
|
|
|
#if defined(WEBRTC_ARCH_X86_FAMILY)
|
|
|
|
#if defined(WEBRTC_ENABLE_AVX2)
|
|
// xgetbv returns the value of an Intel Extended Control Register (XCR).
|
|
// Currently only XCR0 is defined by Intel so `xcr` should always be zero.
|
|
static uint64_t xgetbv(uint32_t xcr) {
|
|
#if defined(_MSC_VER)
|
|
return _xgetbv(xcr);
|
|
#else
|
|
uint32_t eax, edx;
|
|
|
|
__asm__ volatile("xgetbv" : "=a"(eax), "=d"(edx) : "c"(xcr));
|
|
return (static_cast<uint64_t>(edx) << 32) | eax;
|
|
#endif // _MSC_VER
|
|
}
|
|
#endif // WEBRTC_ENABLE_AVX2
|
|
|
|
#ifndef _MSC_VER
|
|
// Intrinsic for "cpuid".
|
|
#if defined(__pic__) && defined(__i386__)
|
|
static inline void __cpuid(int cpu_info[4], int info_type) {
|
|
__asm__ volatile(
|
|
"mov %%ebx, %%edi\n"
|
|
"cpuid\n"
|
|
"xchg %%edi, %%ebx\n"
|
|
: "=a"(cpu_info[0]), "=D"(cpu_info[1]), "=c"(cpu_info[2]),
|
|
"=d"(cpu_info[3])
|
|
: "a"(info_type));
|
|
}
|
|
#else
|
|
static inline void __cpuid(int cpu_info[4], int info_type) {
|
|
__asm__ volatile("cpuid\n"
|
|
: "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]),
|
|
"=d"(cpu_info[3])
|
|
: "a"(info_type), "c"(0));
|
|
}
|
|
#endif
|
|
#endif // _MSC_VER
|
|
#endif // WEBRTC_ARCH_X86_FAMILY
|
|
|
|
#if defined(WEBRTC_ARCH_X86_FAMILY)
|
|
// Actual feature detection for x86.
|
|
int GetCPUInfo(CPUFeature feature) {
|
|
int cpu_info[4];
|
|
__cpuid(cpu_info, 1);
|
|
if (feature == kSSE2) {
|
|
return 0 != (cpu_info[3] & 0x04000000);
|
|
}
|
|
if (feature == kSSE3) {
|
|
return 0 != (cpu_info[2] & 0x00000001);
|
|
}
|
|
#if defined(WEBRTC_ENABLE_AVX2)
|
|
if (feature == kAVX2) {
|
|
int cpu_info7[4];
|
|
__cpuid(cpu_info7, 0);
|
|
int num_ids = cpu_info7[0];
|
|
if (num_ids < 7) {
|
|
return 0;
|
|
}
|
|
// Interpret CPU feature information.
|
|
__cpuid(cpu_info7, 7);
|
|
|
|
// AVX instructions can be used when
|
|
// a) AVX are supported by the CPU,
|
|
// b) XSAVE is supported by the CPU,
|
|
// c) XSAVE is enabled by the kernel.
|
|
// Compiling with MSVC and /arch:AVX2 surprisingly generates BMI2
|
|
// instructions (see crbug.com/1315519).
|
|
return (cpu_info[2] & 0x10000000) != 0 /* AVX */ &&
|
|
(cpu_info[2] & 0x04000000) != 0 /* XSAVE */ &&
|
|
(cpu_info[2] & 0x08000000) != 0 /* OSXSAVE */ &&
|
|
(xgetbv(0) & 0x00000006) == 6 /* XSAVE enabled by kernel */ &&
|
|
(cpu_info7[1] & 0x00000020) != 0 /* AVX2 */ &&
|
|
(cpu_info7[1] & 0x00000100) != 0 /* BMI2 */;
|
|
}
|
|
#endif // WEBRTC_ENABLE_AVX2
|
|
if (feature == kFMA3) {
|
|
return 0 != (cpu_info[2] & 0x00001000);
|
|
}
|
|
return 0;
|
|
}
|
|
#else
|
|
// Default to straight C for other platforms.
|
|
int GetCPUInfo(CPUFeature feature) {
|
|
(void)feature;
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
} // namespace webrtc
|