the various compareAndExchange intrinsics in aarch64.ad potentially clobber the address register:

;; cmpxchg {
          0x0000007f88b5919c: ldxr w0, [x0]
          0x0000007f88b591a0: cmp w0, w2
          0x0000007f88b591a4: b.ne 0x0000007f88b591b0
          0x0000007f88b591a8: stlxr w8, w3, [x0]
          0x0000007f88b591ac: cbnz w8, 0x0000007f88b5919c
         ;; } cmpxchg

This is very bad because it's subsequently used (within the same instruction) for the store-exclusive. It results in occasional segfaults.