Use correct register for aarch64 iOS thread ID (#218)
diff --git a/rpmalloc/rpmalloc.c b/rpmalloc/rpmalloc.c
index 4149283..fa4e025 100644
--- a/rpmalloc/rpmalloc.c
+++ b/rpmalloc/rpmalloc.c
@@ -713,7 +713,12 @@
# elif defined(__arm__)
__asm__ volatile ("mrc p15, 0, %0, c13, c0, 3" : "=r" (tid));
# elif defined(__aarch64__)
+# if defined(__MACH__)
+ // tpidr_el0 likely unused, always return 0 on iOs
+ __asm__ volatile ("mrs %0, tpidrro_el0" : "=r" (tid));
+# else
__asm__ volatile ("mrs %0, tpidr_el0" : "=r" (tid));
+# endif
# else
tid = (uintptr_t)((void*)get_thread_heap_raw());
# endif
