mirror of
https://github.com/google/cpu_features.git
synced 2025-04-27 23:22:31 +02:00
[NFC] refactor the code so it's easier to understand the execution flow (#161)
This commit is contained in:
Guillaume Chatelet
GitHub
parent
40ef93802f
commit
646b80fa3a
@ -1181,41 +1181,11 @@ static bool GetDarwinSysCtlByName(const char* name) {
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// Internal structure to hold the OS support for vector operations.
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// Avoid to recompute them since each call to cpuid is ~100 cycles.
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typedef struct {
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bool have_sse_via_os;
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bool have_sse_via_cpuid;
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bool have_avx;
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bool have_avx512;
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bool have_amx;
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} OsSupport;
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static const OsSupport kEmptyOsSupport;
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static OsSupport CheckOsSupport(const uint32_t max_cpuid_leaf) {
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const Leaf leaf_1 = SafeCpuId(max_cpuid_leaf, 1);
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const bool have_xsave = IsBitSet(leaf_1.ecx, 26);
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const bool have_osxsave = IsBitSet(leaf_1.ecx, 27);
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const bool have_xcr0 = have_xsave && have_osxsave;
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OsSupport os_support = kEmptyOsSupport;
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if (have_xcr0) {
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// AVX capable cpu will expose XCR0.
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const uint32_t xcr0_eax = GetXCR0Eax();
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os_support.have_sse_via_cpuid = HasXmmOsXSave(xcr0_eax);
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os_support.have_avx = HasYmmOsXSave(xcr0_eax);
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#if defined(CPU_FEATURES_OS_DARWIN)
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os_support.have_avx512 = GetDarwinSysCtlByName("hw.optional.avx512f");
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#else
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os_support.have_avx512 = HasZmmOsXSave(xcr0_eax);
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#endif // CPU_FEATURES_OS_DARWIN
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os_support.have_amx = HasTmmOsXSave(xcr0_eax);
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} else {
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// Atom based or older cpus need to ask the OS for sse support.
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os_support.have_sse_via_os = true;
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}
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return os_support;
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}
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bool sse_registers;
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bool avx_registers;
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bool avx512_registers;
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bool amx_registers;
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} OsPreserves;
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#if defined(CPU_FEATURES_OS_WINDOWS)
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#if defined(CPU_FEATURES_MOCK_CPUID_X86)
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@ -1227,60 +1197,17 @@ static bool GetWindowsIsProcessorFeaturePresent(DWORD ProcessorFeature) {
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#endif
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#endif // CPU_FEATURES_OS_WINDOWS
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static void DetectSseViaOs(X86Features* features) {
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#if defined(CPU_FEATURES_OS_WINDOWS)
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// https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-isprocessorfeaturepresent
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features->sse =
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GetWindowsIsProcessorFeaturePresent(PF_XMMI_INSTRUCTIONS_AVAILABLE);
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features->sse2 =
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GetWindowsIsProcessorFeaturePresent(PF_XMMI64_INSTRUCTIONS_AVAILABLE);
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features->sse3 =
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GetWindowsIsProcessorFeaturePresent(PF_SSE3_INSTRUCTIONS_AVAILABLE);
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#elif defined(CPU_FEATURES_OS_DARWIN)
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// Handling Darwin platform through sysctlbyname.
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features->sse = GetDarwinSysCtlByName("hw.optional.sse");
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features->sse2 = GetDarwinSysCtlByName("hw.optional.sse2");
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features->sse3 = GetDarwinSysCtlByName("hw.optional.sse3");
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features->ssse3 = GetDarwinSysCtlByName("hw.optional.supplementalsse3");
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features->sse4_1 = GetDarwinSysCtlByName("hw.optional.sse4_1");
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features->sse4_2 = GetDarwinSysCtlByName("hw.optional.sse4_2");
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#elif defined(CPU_FEATURES_OS_LINUX_OR_ANDROID)
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// Handling Linux platform through /proc/cpuinfo.
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const int fd = CpuFeatures_OpenFile("/proc/cpuinfo");
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if (fd >= 0) {
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StackLineReader reader;
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StackLineReader_Initialize(&reader, fd);
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for (;;) {
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const LineResult result = StackLineReader_NextLine(&reader);
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const StringView line = result.line;
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StringView key, value;
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if (CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value)) {
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if (CpuFeatures_StringView_IsEquals(key, str("flags"))) {
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features->sse = CpuFeatures_StringView_HasWord(value, "sse");
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features->sse2 = CpuFeatures_StringView_HasWord(value, "sse2");
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features->sse3 = CpuFeatures_StringView_HasWord(value, "sse3");
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features->ssse3 = CpuFeatures_StringView_HasWord(value, "ssse3");
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features->sse4_1 = CpuFeatures_StringView_HasWord(value, "sse4_1");
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features->sse4_2 = CpuFeatures_StringView_HasWord(value, "sse4_2");
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break;
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}
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}
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if (result.eof) break;
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}
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CpuFeatures_CloseFile(fd);
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}
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#else
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#error "Unsupported fallback detection of SSE OS support."
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#endif
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}
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// Reference https://en.wikipedia.org/wiki/CPUID.
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static void ParseCpuId(const uint32_t max_cpuid_leaf,
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const OsSupport os_support, X86Info* info) {
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static void ParseCpuId(const uint32_t max_cpuid_leaf, X86Info* info,
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OsPreserves* os_preserves) {
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const Leaf leaf_1 = SafeCpuId(max_cpuid_leaf, 1);
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const Leaf leaf_7 = SafeCpuId(max_cpuid_leaf, 7);
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const Leaf leaf_7_1 = SafeCpuIdEx(max_cpuid_leaf, 7, 1);
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const bool have_xsave = IsBitSet(leaf_1.ecx, 26);
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const bool have_osxsave = IsBitSet(leaf_1.ecx, 27);
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const bool have_xcr0 = have_xsave && have_osxsave;
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const uint32_t family = ExtractBitRange(leaf_1.eax, 11, 8);
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const uint32_t extended_family = ExtractBitRange(leaf_1.eax, 27, 20);
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const uint32_t model = ExtractBitRange(leaf_1.eax, 7, 4);
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@ -1321,72 +1248,144 @@ static void ParseCpuId(const uint32_t max_cpuid_leaf,
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features->vpclmulqdq = IsBitSet(leaf_7.ecx, 10);
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features->adx = IsBitSet(leaf_7.ebx, 19);
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if (os_support.have_sse_via_os) {
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DetectSseViaOs(features);
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} else if (os_support.have_sse_via_cpuid) {
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features->sse = IsBitSet(leaf_1.edx, 25);
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features->sse2 = IsBitSet(leaf_1.edx, 26);
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features->sse3 = IsBitSet(leaf_1.ecx, 0);
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features->ssse3 = IsBitSet(leaf_1.ecx, 9);
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features->sse4_1 = IsBitSet(leaf_1.ecx, 19);
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features->sse4_2 = IsBitSet(leaf_1.ecx, 20);
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}
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/////////////////////////////////////////////////////////////////////////////
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// The following section is devoted to Vector Extensions.
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/////////////////////////////////////////////////////////////////////////////
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if (os_support.have_avx) {
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features->fma3 = IsBitSet(leaf_1.ecx, 12);
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features->avx = IsBitSet(leaf_1.ecx, 28);
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features->avx2 = IsBitSet(leaf_7.ebx, 5);
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}
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// CPU with AVX expose XCR0 which enables checking vector extensions OS
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// support through cpuid.
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if (have_xcr0) {
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// Here we rely exclusively on cpuid for both CPU and OS support of vector
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// extensions.
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const uint32_t xcr0_eax = GetXCR0Eax();
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os_preserves->sse_registers = HasXmmOsXSave(xcr0_eax);
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os_preserves->avx_registers = HasYmmOsXSave(xcr0_eax);
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#if defined(CPU_FEATURES_OS_DARWIN)
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// On Darwin AVX512 support is On-demand.
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// We have to query the OS instead of querying the Zmm save/restore state.
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// https://github.com/apple/darwin-xnu/blob/8f02f2a044b9bb1ad951987ef5bab20ec9486310/osfmk/i386/fpu.c#L173-L199
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os_preserves->avx512_registers =
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GetDarwinSysCtlByName("hw.optional.avx512f");
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#else
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os_preserves->avx512_registers = HasZmmOsXSave(xcr0_eax);
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#endif // CPU_FEATURES_OS_DARWIN
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os_preserves->amx_registers = HasTmmOsXSave(xcr0_eax);
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if (os_support.have_avx512) {
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features->avx512f = IsBitSet(leaf_7.ebx, 16);
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features->avx512cd = IsBitSet(leaf_7.ebx, 28);
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features->avx512er = IsBitSet(leaf_7.ebx, 27);
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features->avx512pf = IsBitSet(leaf_7.ebx, 26);
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features->avx512bw = IsBitSet(leaf_7.ebx, 30);
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features->avx512dq = IsBitSet(leaf_7.ebx, 17);
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features->avx512vl = IsBitSet(leaf_7.ebx, 31);
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features->avx512ifma = IsBitSet(leaf_7.ebx, 21);
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features->avx512vbmi = IsBitSet(leaf_7.ecx, 1);
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features->avx512vbmi2 = IsBitSet(leaf_7.ecx, 6);
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features->avx512vnni = IsBitSet(leaf_7.ecx, 11);
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features->avx512bitalg = IsBitSet(leaf_7.ecx, 12);
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features->avx512vpopcntdq = IsBitSet(leaf_7.ecx, 14);
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features->avx512_4vnniw = IsBitSet(leaf_7.edx, 2);
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features->avx512_4vbmi2 = IsBitSet(leaf_7.edx, 3);
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features->avx512_second_fma = HasSecondFMA(info->model);
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features->avx512_4fmaps = IsBitSet(leaf_7.edx, 3);
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features->avx512_bf16 = IsBitSet(leaf_7_1.eax, 5);
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features->avx512_vp2intersect = IsBitSet(leaf_7.edx, 8);
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}
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if (os_support.have_amx) {
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features->amx_bf16 = IsBitSet(leaf_7.edx, 22);
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features->amx_tile = IsBitSet(leaf_7.edx, 24);
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features->amx_int8 = IsBitSet(leaf_7.edx, 25);
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if (os_preserves->sse_registers) {
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features->sse = IsBitSet(leaf_1.edx, 25);
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features->sse2 = IsBitSet(leaf_1.edx, 26);
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features->sse3 = IsBitSet(leaf_1.ecx, 0);
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features->ssse3 = IsBitSet(leaf_1.ecx, 9);
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features->sse4_1 = IsBitSet(leaf_1.ecx, 19);
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features->sse4_2 = IsBitSet(leaf_1.ecx, 20);
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}
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if (os_preserves->avx_registers) {
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features->fma3 = IsBitSet(leaf_1.ecx, 12);
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features->avx = IsBitSet(leaf_1.ecx, 28);
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features->avx2 = IsBitSet(leaf_7.ebx, 5);
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}
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if (os_preserves->avx512_registers) {
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features->avx512f = IsBitSet(leaf_7.ebx, 16);
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features->avx512cd = IsBitSet(leaf_7.ebx, 28);
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features->avx512er = IsBitSet(leaf_7.ebx, 27);
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features->avx512pf = IsBitSet(leaf_7.ebx, 26);
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features->avx512bw = IsBitSet(leaf_7.ebx, 30);
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features->avx512dq = IsBitSet(leaf_7.ebx, 17);
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features->avx512vl = IsBitSet(leaf_7.ebx, 31);
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features->avx512ifma = IsBitSet(leaf_7.ebx, 21);
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features->avx512vbmi = IsBitSet(leaf_7.ecx, 1);
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features->avx512vbmi2 = IsBitSet(leaf_7.ecx, 6);
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features->avx512vnni = IsBitSet(leaf_7.ecx, 11);
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features->avx512bitalg = IsBitSet(leaf_7.ecx, 12);
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features->avx512vpopcntdq = IsBitSet(leaf_7.ecx, 14);
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features->avx512_4vnniw = IsBitSet(leaf_7.edx, 2);
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features->avx512_4vbmi2 = IsBitSet(leaf_7.edx, 3);
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features->avx512_second_fma = HasSecondFMA(info->model);
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features->avx512_4fmaps = IsBitSet(leaf_7.edx, 3);
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features->avx512_bf16 = IsBitSet(leaf_7_1.eax, 5);
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features->avx512_vp2intersect = IsBitSet(leaf_7.edx, 8);
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}
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if (os_preserves->amx_registers) {
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features->amx_bf16 = IsBitSet(leaf_7.edx, 22);
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features->amx_tile = IsBitSet(leaf_7.edx, 24);
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features->amx_int8 = IsBitSet(leaf_7.edx, 25);
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}
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} else {
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// When XCR0 is not available (Atom based or older cpus) we need to defer to
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// the OS via custom code.
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#if defined(CPU_FEATURES_OS_WINDOWS)
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// Handling Windows platform through IsProcessorFeaturePresent.
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// https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-isprocessorfeaturepresent
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features->sse =
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GetWindowsIsProcessorFeaturePresent(PF_XMMI_INSTRUCTIONS_AVAILABLE);
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features->sse2 =
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GetWindowsIsProcessorFeaturePresent(PF_XMMI64_INSTRUCTIONS_AVAILABLE);
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features->sse3 =
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GetWindowsIsProcessorFeaturePresent(PF_SSE3_INSTRUCTIONS_AVAILABLE);
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#elif defined(CPU_FEATURES_OS_DARWIN)
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// Handling Darwin platform through sysctlbyname.
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features->sse = GetDarwinSysCtlByName("hw.optional.sse");
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features->sse2 = GetDarwinSysCtlByName("hw.optional.sse2");
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features->sse3 = GetDarwinSysCtlByName("hw.optional.sse3");
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features->ssse3 = GetDarwinSysCtlByName("hw.optional.supplementalsse3");
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features->sse4_1 = GetDarwinSysCtlByName("hw.optional.sse4_1");
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features->sse4_2 = GetDarwinSysCtlByName("hw.optional.sse4_2");
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#elif defined(CPU_FEATURES_OS_LINUX_OR_ANDROID)
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// Handling Linux platform through /proc/cpuinfo.
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const int fd = CpuFeatures_OpenFile("/proc/cpuinfo");
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if (fd >= 0) {
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StackLineReader reader;
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StackLineReader_Initialize(&reader, fd);
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for (;;) {
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const LineResult result = StackLineReader_NextLine(&reader);
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const StringView line = result.line;
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StringView key, value;
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if (CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value)) {
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if (CpuFeatures_StringView_IsEquals(key, str("flags"))) {
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features->sse = CpuFeatures_StringView_HasWord(value, "sse");
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features->sse2 = CpuFeatures_StringView_HasWord(value, "sse2");
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features->sse3 = CpuFeatures_StringView_HasWord(value, "sse3");
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features->ssse3 = CpuFeatures_StringView_HasWord(value, "ssse3");
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features->sse4_1 = CpuFeatures_StringView_HasWord(value, "sse4_1");
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features->sse4_2 = CpuFeatures_StringView_HasWord(value, "sse4_2");
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break;
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}
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}
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if (result.eof) break;
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}
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CpuFeatures_CloseFile(fd);
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}
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#else
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#error "Unsupported fallback detection of SSE OS support."
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#endif
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// Now that we have queried the OS for SSE support, we report this back to
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// os_preserves. This is needed in case of AMD CPU's to enable testing of
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// sse4a (See ParseExtraAMDCpuId below).
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if (features->sse) os_preserves->sse_registers = true;
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}
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}
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// Reference
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// https://en.wikipedia.org/wiki/CPUID#EAX=80000000h:_Get_Highest_Extended_Function_Implemented.
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static void ParseExtraAMDCpuId(X86Info* info, OsSupport os_support) {
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static void ParseExtraAMDCpuId(X86Info* info, OsPreserves os_preserves) {
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const Leaf leaf_80000000 = CpuId(0x80000000);
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const uint32_t max_extended_cpuid_leaf = leaf_80000000.eax;
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const Leaf leaf_80000001 = SafeCpuId(max_extended_cpuid_leaf, 0x80000001);
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X86Features* const features = &info->features;
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if (os_support.have_sse_via_cpuid) {
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if (os_preserves.sse_registers) {
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features->sse4a = IsBitSet(leaf_80000001.ecx, 6);
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}
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if (os_support.have_avx) {
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if (os_preserves.avx_registers) {
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features->fma4 = IsBitSet(leaf_80000001.ecx, 16);
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}
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}
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static const X86Info kEmptyX86Info;
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static const CacheInfo kEmptyCacheInfo;
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static const OsPreserves kEmptyOsPreserves;
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X86Info GetX86Info(void) {
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X86Info info = kEmptyX86Info;
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@ -1395,11 +1394,11 @@ X86Info GetX86Info(void) {
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const bool is_amd = IsVendor(leaf_0, "AuthenticAMD");
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SetVendor(leaf_0, info.vendor);
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if (is_intel || is_amd) {
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OsPreserves os_preserves = kEmptyOsPreserves;
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const uint32_t max_cpuid_leaf = leaf_0.eax;
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const OsSupport os_support = CheckOsSupport(max_cpuid_leaf);
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ParseCpuId(max_cpuid_leaf, os_support, &info);
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ParseCpuId(max_cpuid_leaf, &info, &os_preserves);
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if (is_amd) {
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ParseExtraAMDCpuId(&info, os_support);
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ParseExtraAMDCpuId(&info, os_preserves);
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}
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}
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return info;
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