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#include <TargetConditionals.h>
#if TARGET_OS_OSX || TARGET_OS_IPHONE
#include <sys/sysctl.h>
#if __has_include(<arm/cpu_capabilities_public.h>)
#include <arm/cpu_capabilities_public.h>
#define HAS_CPU_CAPABILITIES_PUBLIC_H 1
// FB13964283 - A few of these didn't make it into the public SDK yet.
#ifndef CAP_BIT_FEAT_SME
#define CAP_BIT_FEAT_SME 40
#endif
#ifndef CAP_BIT_FEAT_SME2
#define CAP_BIT_FEAT_SME2 41
#endif
#ifndef CAP_BIT_FEAT_SME_F64F64
#define CAP_BIT_FEAT_SME_F64F64 42
#endif
#ifndef CAP_BIT_FEAT_SME_I16I64
#define CAP_BIT_FEAT_SME_I16I64 43
#endif
#endif
static bool isKnownAndSupported(const char *name) {
int32_t val = 0;
size_t size = sizeof(val);
if (sysctlbyname(name, &val, &size, NULL, 0))
return false;
return val;
}
static uint64_t deriveImplicitFeatures(uint64_t features) {
// FEAT_SSBS2 implies FEAT_SSBS
if ((1ULL << FEAT_SSBS2) & features)
features |= (1ULL << FEAT_SSBS);
// FEAT_FP is always enabled
features |= (1ULL << FEAT_FP);
features |= (1ULL << FEAT_INIT);
return features;
}
void __init_cpu_features_resolver(void) {
// On Darwin platforms, this may be called concurrently by multiple threads
// because the resolvers that use it are called lazily at runtime (unlike on
// ELF platforms, where IFuncs are resolved serially at load time). This
// function's effect on __aarch64_cpu_features must be idempotent.
if (__atomic_load_n(&__aarch64_cpu_features.features, __ATOMIC_RELAXED))
return;
uint64_t features = 0;
#ifdef HAS_CPU_CAPABILITIES_PUBLIC_H
uint8_t feats_bitvec[(CAP_BIT_NB + 7) / 8] = {0};
size_t len = sizeof(feats_bitvec);
// When hw.optional.arm.feats is available (macOS 15.0+, iOS 18.0+), use the
// fast path to get all the feature bits, otherwise fall back to the slow
// ~20-something sysctls path.
if (!sysctlbyname("hw.optional.arm.caps", &feats_bitvec, &len, 0, 0)) {
#define CHECK_BIT(FROM, TO) \
do { \
if (feats_bitvec[FROM / 8] & (1u << ((FROM) & 7))) { \
features |= (1ULL << TO); \
} \
} while (0)
CHECK_BIT(CAP_BIT_FEAT_FlagM, FEAT_FLAGM);
CHECK_BIT(CAP_BIT_FEAT_FlagM2, FEAT_FLAGM2);
CHECK_BIT(CAP_BIT_FEAT_FHM, FEAT_FP16FML);
CHECK_BIT(CAP_BIT_FEAT_DotProd, FEAT_DOTPROD);
CHECK_BIT(CAP_BIT_FEAT_SHA3, FEAT_SHA3);
CHECK_BIT(CAP_BIT_FEAT_RDM, FEAT_RDM);
CHECK_BIT(CAP_BIT_FEAT_LSE, FEAT_LSE);
CHECK_BIT(CAP_BIT_FEAT_SHA256, FEAT_SHA2);
CHECK_BIT(CAP_BIT_FEAT_SHA1, FEAT_SHA1);
CHECK_BIT(CAP_BIT_FEAT_AES, FEAT_AES);
CHECK_BIT(CAP_BIT_FEAT_PMULL, FEAT_PMULL);
CHECK_BIT(CAP_BIT_FEAT_SPECRES, FEAT_PREDRES);
CHECK_BIT(CAP_BIT_FEAT_SB, FEAT_SB);
CHECK_BIT(CAP_BIT_FEAT_FRINTTS, FEAT_FRINTTS);
CHECK_BIT(CAP_BIT_FEAT_LRCPC, FEAT_RCPC);
CHECK_BIT(CAP_BIT_FEAT_LRCPC2, FEAT_RCPC2);
CHECK_BIT(CAP_BIT_FEAT_FCMA, FEAT_FCMA);
CHECK_BIT(CAP_BIT_FEAT_JSCVT, FEAT_JSCVT);
CHECK_BIT(CAP_BIT_FEAT_DPB, FEAT_DPB);
CHECK_BIT(CAP_BIT_FEAT_DPB2, FEAT_DPB2);
CHECK_BIT(CAP_BIT_FEAT_BF16, FEAT_BF16);
CHECK_BIT(CAP_BIT_FEAT_I8MM, FEAT_I8MM);
CHECK_BIT(CAP_BIT_FEAT_DIT, FEAT_DIT);
CHECK_BIT(CAP_BIT_FEAT_FP16, FEAT_FP16);
CHECK_BIT(CAP_BIT_FEAT_SSBS, FEAT_SSBS2);
CHECK_BIT(CAP_BIT_FEAT_BTI, FEAT_BTI);
CHECK_BIT(CAP_BIT_AdvSIMD, FEAT_SIMD);
CHECK_BIT(CAP_BIT_CRC32, FEAT_CRC);
CHECK_BIT(CAP_BIT_FEAT_SME, FEAT_SME);
CHECK_BIT(CAP_BIT_FEAT_SME2, FEAT_SME2);
CHECK_BIT(CAP_BIT_FEAT_SME_F64F64, FEAT_SME_F64);
CHECK_BIT(CAP_BIT_FEAT_SME_I16I64, FEAT_SME_I64);
features = deriveImplicitFeatures(features);
__atomic_store(&__aarch64_cpu_features.features, &features,
__ATOMIC_RELAXED);
return;
}
#endif
// https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics
static const struct {
const char *sysctl_name;
enum CPUFeatures feature;
} feature_checks[] = {
{"hw.optional.arm.FEAT_FlagM", FEAT_FLAGM},
{"hw.optional.arm.FEAT_FlagM2", FEAT_FLAGM2},
{"hw.optional.arm.FEAT_FHM", FEAT_FP16FML},
{"hw.optional.arm.FEAT_DotProd", FEAT_DOTPROD},
{"hw.optional.arm.FEAT_RDM", FEAT_RDM},
{"hw.optional.arm.FEAT_LSE", FEAT_LSE},
{"hw.optional.AdvSIMD", FEAT_SIMD},
{"hw.optional.armv8_crc32", FEAT_CRC},
{"hw.optional.arm.FEAT_SHA1", FEAT_SHA1},
{"hw.optional.arm.FEAT_SHA256", FEAT_SHA2},
{"hw.optional.arm.FEAT_SHA3", FEAT_SHA3},
{"hw.optional.arm.FEAT_AES", FEAT_AES},
{"hw.optional.arm.FEAT_PMULL", FEAT_PMULL},
{"hw.optional.arm.FEAT_FP16", FEAT_FP16},
{"hw.optional.arm.FEAT_DIT", FEAT_DIT},
{"hw.optional.arm.FEAT_DPB", FEAT_DPB},
{"hw.optional.arm.FEAT_DPB2", FEAT_DPB2},
{"hw.optional.arm.FEAT_JSCVT", FEAT_JSCVT},
{"hw.optional.arm.FEAT_FCMA", FEAT_FCMA},
{"hw.optional.arm.FEAT_LRCPC", FEAT_RCPC},
{"hw.optional.arm.FEAT_LRCPC2", FEAT_RCPC2},
{"hw.optional.arm.FEAT_FRINTTS", FEAT_FRINTTS},
{"hw.optional.arm.FEAT_I8MM", FEAT_I8MM},
{"hw.optional.arm.FEAT_BF16", FEAT_BF16},
{"hw.optional.arm.FEAT_SB", FEAT_SB},
{"hw.optional.arm.FEAT_SPECRES", FEAT_PREDRES},
{"hw.optional.arm.FEAT_SSBS", FEAT_SSBS2},
{"hw.optional.arm.FEAT_BTI", FEAT_BTI},
};
for (size_t I = 0, E = sizeof(feature_checks) / sizeof(feature_checks[0]);
I != E; ++I)
if (isKnownAndSupported(feature_checks[I].sysctl_name))
features |= (1ULL << feature_checks[I].feature);
features = deriveImplicitFeatures(features);
__atomic_store(&__aarch64_cpu_features.features, &features,
__ATOMIC_RELAXED);
}
#endif // TARGET_OS_OSX || TARGET_OS_IPHONE
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