================
@@ -0,0 +1,69 @@
+#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[] = {
----------------
jroelofs wrote:
Ohh, I see you're asking a different question than I thought. Yeah, those three
would probably be useful. Unfortunately, looks like we're just about out of
bits in `__aarch64_cpu_features.features`.
https://github.com/llvm/llvm-project/pull/75636
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