================
@@ -1259,6 +1270,72 @@ struct {
// As features grows new fields could be added
} __aarch64_cpu_features __attribute__((visibility("hidden"), nocommon));
+#if defined(__APPLE__)
+#include <TargetConditionals.h>
+#if TARGET_OS_OSX || TARGET_OS_IPHONE
+#include <dispatch/dispatch.h>
+#include <sys/sysctl.h>
+
+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;
+}
+
+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 should be idempotent, but even
+ // so we need dispatch_once to resolve the race condition. Dispatch is
+ // available through libSystem, which we need anyway for the sysctl, so this
+ // does not add a new dependency.
+
+ static dispatch_once_t onceToken = 0;
+ dispatch_once(&onceToken, ^{
+ //
https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics
+ static struct {
+ const char *sysctl_name;
+ enum CPUFeatures feature;
+ } features[] = {
+ {"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.floatingpoint", FEAT_FP},
+ {"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.armv8_2_sha3", FEAT_SHA3},
----------------
ahmedbougacha wrote:
I think you want `FEAT_SHA3` instead of `armv8_2_sha3` (and technically, sha512
also, but that shouldn't matter; crypto's a mess). I thought we had one for
crc32 as well, but looks like we don't. I assume FP/SIMD are unneeded but
harmless.
Otherwise, sysctl `FEAT_SPECRES` should map to enum `PREDRES`, and DIT,
DPB/DPB2 are missing (DIT is vaguely plausibly useful, DPB not really.) Rest
LGTM!
https://github.com/llvm/llvm-project/pull/73685
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