--- old/src/cpu/aarch64/vm/c1_LIRAssembler_aarch64.cpp	2017-09-21 10:12:17.588301994 -0400
+++ new/src/cpu/aarch64/vm/c1_LIRAssembler_aarch64.cpp	2017-09-21 10:12:17.324291920 -0400
@@ -1595,7 +1595,16 @@
 
 void LIR_Assembler::emit_compare_and_swap(LIR_OpCompareAndSwap* op) {
   assert(VM_Version::supports_cx8(), "wrong machine");
-  Register addr = as_reg(op->addr());
+  Register addr;
+  if (op->addr()->is_register()) {
+    addr = as_reg(op->addr());
+  } else {
+    assert(op->addr()->is_address(), "what else?");
+    LIR_Address* addr_ptr = op->addr()->as_address_ptr();
+    assert(addr_ptr->disp() == 0, "need 0 disp");
+    assert(addr_ptr->index() == LIR_OprDesc::illegalOpr(), "need 0 index");
+    addr = as_reg(addr_ptr->base());
+  }
   Register newval = as_reg(op->new_value());
   Register cmpval = as_reg(op->cmp_value());
   Label succeed, fail, around;