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niklase@google.com470e71d2011-07-07 08:21:251/*
2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
ajm@google.comce7c2a22011-08-04 01:50:0011// Parts of this file derived from Chromium's base/cpu.cc.
12
Niels Möllera12c42a2018-07-25 14:05:4813#include "rtc_base/system/arch.h"
Mirko Bonadei92ea95e2017-09-15 04:47:3114#include "system_wrappers/include/cpu_features_wrapper.h"
Per Åhgrena43178c2020-09-25 10:02:3215#include "system_wrappers/include/field_trial.h"
niklase@google.com470e71d2011-07-07 08:21:2516
phoglund@webrtc.orgb15d2852012-11-21 08:02:5717#if defined(WEBRTC_ARCH_X86_FAMILY) && defined(_MSC_VER)
ajm@google.comce7c2a22011-08-04 01:50:0018#include <intrin.h>
19#endif
phoglund@webrtc.orgb15d2852012-11-21 08:02:5720
Mirko Bonadeibef022b2020-09-06 14:07:1521namespace webrtc {
22
niklase@google.com470e71d2011-07-07 08:21:2523// No CPU feature is available => straight C path.
24int GetCPUInfoNoASM(CPUFeature feature) {
25 (void)feature;
26 return 0;
27}
28
ajm@google.comce7c2a22011-08-04 01:50:0029#if defined(WEBRTC_ARCH_X86_FAMILY)
Zhaoliang Ma72e43212020-08-17 09:13:4130
31#if defined(WEBRTC_ENABLE_AVX2)
32// xgetbv returns the value of an Intel Extended Control Register (XCR).
Artem Titovf0671922021-07-27 10:40:1733// Currently only XCR0 is defined by Intel so `xcr` should always be zero.
Zhaoliang Ma72e43212020-08-17 09:13:4134static uint64_t xgetbv(uint32_t xcr) {
35#if defined(_MSC_VER)
36 return _xgetbv(xcr);
37#else
38 uint32_t eax, edx;
39
40 __asm__ volatile("xgetbv" : "=a"(eax), "=d"(edx) : "c"(xcr));
41 return (static_cast<uint64_t>(edx) << 32) | eax;
42#endif // _MSC_VER
43}
44#endif // WEBRTC_ENABLE_AVX2
45
ajm@google.comce7c2a22011-08-04 01:50:0046#ifndef _MSC_VER
niklase@google.com470e71d2011-07-07 08:21:2547// Intrinsic for "cpuid".
48#if defined(__pic__) && defined(__i386__)
ajm@google.comce7c2a22011-08-04 01:50:0049static inline void __cpuid(int cpu_info[4], int info_type) {
phoglund@webrtc.orgb15d2852012-11-21 08:02:5750 __asm__ volatile(
Karl Wiberg79eb1d92017-11-08 11:26:0751 "mov %%ebx, %%edi\n"
52 "cpuid\n"
53 "xchg %%edi, %%ebx\n"
54 : "=a"(cpu_info[0]), "=D"(cpu_info[1]), "=c"(cpu_info[2]),
55 "=d"(cpu_info[3])
56 : "a"(info_type));
niklase@google.com470e71d2011-07-07 08:21:2557}
ajm@google.comce7c2a22011-08-04 01:50:0058#else
59static inline void __cpuid(int cpu_info[4], int info_type) {
Karl Wiberg79eb1d92017-11-08 11:26:0760 __asm__ volatile("cpuid\n"
61 : "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]),
62 "=d"(cpu_info[3])
Zhaoliang Ma72e43212020-08-17 09:13:4163 : "a"(info_type), "c"(0));
niklase@google.com470e71d2011-07-07 08:21:2564}
65#endif
ajm@google.comce7c2a22011-08-04 01:50:0066#endif // _MSC_VER
67#endif // WEBRTC_ARCH_X86_FAMILY
niklase@google.com470e71d2011-07-07 08:21:2568
ajm@google.comce7c2a22011-08-04 01:50:0069#if defined(WEBRTC_ARCH_X86_FAMILY)
niklase@google.com470e71d2011-07-07 08:21:2570// Actual feature detection for x86.
Mirko Bonadeibef022b2020-09-06 14:07:1571int GetCPUInfo(CPUFeature feature) {
niklase@google.com470e71d2011-07-07 08:21:2572 int cpu_info[4];
ajm@google.comce7c2a22011-08-04 01:50:0073 __cpuid(cpu_info, 1);
niklase@google.com470e71d2011-07-07 08:21:2574 if (feature == kSSE2) {
75 return 0 != (cpu_info[3] & 0x04000000);
76 }
77 if (feature == kSSE3) {
78 return 0 != (cpu_info[2] & 0x00000001);
79 }
Zhaoliang Ma72e43212020-08-17 09:13:4180#if defined(WEBRTC_ENABLE_AVX2)
Per Åhgrena43178c2020-09-25 10:02:3281 if (feature == kAVX2 &&
82 !webrtc::field_trial::IsEnabled("WebRTC-Avx2SupportKillSwitch")) {
Zhaoliang Ma72e43212020-08-17 09:13:4183 int cpu_info7[4];
84 __cpuid(cpu_info7, 0);
85 int num_ids = cpu_info7[0];
86 if (num_ids < 7) {
87 return 0;
88 }
89 // Interpret CPU feature information.
90 __cpuid(cpu_info7, 7);
91
92 // AVX instructions can be used when
93 // a) AVX are supported by the CPU,
94 // b) XSAVE is supported by the CPU,
95 // c) XSAVE is enabled by the kernel.
Gustaf Ullberg8b8d0b52022-04-29 06:54:2996 // Compiling with MSVC and /arch:AVX2 surprisingly generates BMI2
97 // instructions (see crbug.com/1315519).
98 return (cpu_info[2] & 0x10000000) != 0 /* AVX */ &&
Zhaoliang Ma72e43212020-08-17 09:13:4199 (cpu_info[2] & 0x04000000) != 0 /* XSAVE */ &&
100 (cpu_info[2] & 0x08000000) != 0 /* OSXSAVE */ &&
101 (xgetbv(0) & 0x00000006) == 6 /* XSAVE enabled by kernel */ &&
Gustaf Ullberg8b8d0b52022-04-29 06:54:29102 (cpu_info7[1] & 0x00000020) != 0 /* AVX2 */ &&
103 (cpu_info7[1] & 0x00000100) != 0 /* BMI2 */;
Zhaoliang Ma72e43212020-08-17 09:13:41104 }
105#endif // WEBRTC_ENABLE_AVX2
Henrik Lundincb4b0a62023-01-31 15:49:55106 if (feature == kFMA3) {
107 return 0 != (cpu_info[2] & 0x00001000);
108 }
niklase@google.com470e71d2011-07-07 08:21:25109 return 0;
110}
111#else
112// Default to straight C for other platforms.
Mirko Bonadeibef022b2020-09-06 14:07:15113int GetCPUInfo(CPUFeature feature) {
niklase@google.com470e71d2011-07-07 08:21:25114 (void)feature;
115 return 0;
116}
117#endif
118
Mirko Bonadeibef022b2020-09-06 14:07:15119} // namespace webrtc