Common: Add CPU feature detection for ARM64

src/common/CMakeLists.txt

@@ -125,6 +125,12 @@ if(ARCHITECTURE_x86_64)
             x64/xbyak_abi.h
             x64/xbyak_util.h
     )
+elseif(ARCHITECTURE_ARM64)
+    target_sources(common
+        PRIVATE
+            aarch64/cpu_detect.cpp
+            aarch64/cpu_detect.h
+    )
 endif()
 
 create_target_directory_groups(common)

src/common/aarch64/cpu_detect.cpp

@@ -0,0 +1,112 @@
+// Copyright 2013 Dolphin Emulator Project / 2022 Citra Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <cstring>
+#include <fstream>
+#include <string>
+
+#ifdef __APPLE__
+// clang-format off
+#include <sys/types.h>
+#include <sys/sysctl.h>
+// clang-format on
+#elif !defined(_WIN32)
+#ifndef __FreeBSD__
+#include <asm/hwcap.h>
+#endif // __FreeBSD__
+#include <sys/auxv.h>
+#include <unistd.h>
+#endif // __APPLE__
+
+#include "common/aarch64/cpu_detect.h"
+#include "common/file_util.h"
+
+namespace Common {
+
+#ifdef __APPLE__
+static std::string GetCPUString() {
+    char buf[128];
+    size_t buf_len = sizeof(buf);
+    if (sysctlbyname("machdep.cpu.brand_string", &buf, &buf_len, NULL, 0) == -1) {
+        return "Unknown";
+    }
+    return buf;
+}
+#elif !defined(WIN32)
+static std::string GetCPUString() {
+    constexpr char procfile[] = "/proc/cpuinfo";
+    constexpr char marker[] = "Hardware\t: ";
+    std::string cpu_string = "Unknown";
+
+    std::string line;
+    std::ifstream file;
+    OpenFStream(file, procfile, std::ios_base::in);
+
+    if (!file)
+        return cpu_string;
+
+    while (std::getline(file, line)) {
+        if (line.find(marker) != std::string::npos) {
+            cpu_string = line.substr(strlen(marker));
+            break;
+        }
+    }
+
+    return cpu_string;
+}
+#endif // __APPLE__
+
+// Detects the various CPU features
+static CPUCaps Detect() {
+    CPUCaps caps;
+    // Set some defaults here
+    caps.fma = true;
+    caps.afp = false;
+
+#ifdef __APPLE__
+    // M-series CPUs have all of these
+    caps.fp = true;
+    caps.asimd = true;
+    caps.aes = true;
+    caps.crc32 = true;
+    caps.sha1 = true;
+    caps.sha2 = true;
+    caps.cpu_string = GetCPUString();
+#elif defined(_WIN32)
+    // Windows does not provide any mechanism for querying the system registers on ARMv8, unlike
+    // Linux which traps the register reads and emulates them in the kernel. There are environment
+    // variables containing some of the CPU-specific values, which we could use for a lookup table
+    // in the future. For now, assume all features are present as all known devices which are
+    // Windows-on-ARM compatible also support these extensions.
+    caps.fp = true;
+    caps.asimd = true;
+    caps.aes = true;
+    caps.crc32 = true;
+    caps.sha1 = true;
+    caps.sha2 = true;
+#else
+    caps.cpu_string = GetCPUString();
+
+#ifdef __FreeBSD__
+    u_long hwcaps = 0;
+    elf_aux_info(AT_HWCAP, &hwcaps, sizeof(u_long));
+#else
+    unsigned long hwcaps = getauxval(AT_HWCAP);
+#endif // __FreeBSD__
+    caps.fp = hwcaps & HWCAP_FP;
+    caps.asimd = hwcaps & HWCAP_ASIMD;
+    caps.aes = hwcaps & HWCAP_AES;
+    caps.crc32 = hwcaps & HWCAP_CRC32;
+    caps.sha1 = hwcaps & HWCAP_SHA1;
+    caps.sha2 = hwcaps & HWCAP_SHA2;
+#endif // __APPLE__
+    return caps;
+}
+
+const CPUCaps& GetCPUCaps() {
+    static CPUCaps caps = Detect();
+    return caps;
+}
+
+} // namespace Common

src/common/aarch64/cpu_detect.h

@@ -0,0 +1,31 @@
+// Copyright 2013 Dolphin Emulator Project / 2021 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <string>
+
+namespace Common {
+
+/// Arm64 CPU capabilities that may be detected by this module
+struct CPUCaps {
+    std::string cpu_string;
+
+    bool aes;
+    bool afp; // Alternate floating-point behavior
+    bool asimd;
+    bool crc32;
+    bool fma;
+    bool fp;
+    bool sha1;
+    bool sha2;
+};
+
+/**
+ * Gets the supported capabilities of the host CPU
+ * @return Reference to a CPUCaps struct with the detected host CPU capabilities
+ */
+const CPUCaps& GetCPUCaps();
+
+} // namespace Common