diff a/src/hotspot/share/gc/shared/c2/barrierSetC2.cpp b/src/hotspot/share/gc/shared/c2/barrierSetC2.cpp
--- a/src/hotspot/share/gc/shared/c2/barrierSetC2.cpp
+++ b/src/hotspot/share/gc/shared/c2/barrierSetC2.cpp
@@ -127,10 +127,16 @@
     _preserve.remove(OptoReg::as_OptoReg(vm_reg));
     vm_reg = vm_reg->next();
   } while (vm_reg->is_Register() && !vm_reg->is_concrete());
 }
 
+bool BarrierStubC2::is_preserved(Register r) {
+  const VMReg vm_reg = r->as_VMReg();
+  assert(vm_reg->is_Register(), "r must be a general-purpose register");
+  return _preserve.member(OptoReg::as_OptoReg(vm_reg));
+}
+
 const RegMask& BarrierStubC2::preserve_set() const {
   return _preserve;
 }
 
 Node* BarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue& val) const {
@@ -1109,11 +1115,11 @@
       const uint mem_index = block_index(mem_block, mem);
 
       if (access_block == mem_block) {
         // Earlier accesses in the same block
         if (mem_index < access_index && !block_has_safepoint(mem_block, mem_index + 1, access_index)) {
-          elide_dominated_barrier(access);
+          elide_dominated_barrier(access, mem->is_Mach() ? mem->as_Mach() : nullptr);
         }
       } else if (mem_block->dominates(access_block)) {
         // Dominating block? Look around for safepoints
         ResourceMark rm;
         Block_List stack;
@@ -1139,11 +1145,11 @@
             stack.push(pred);
           }
         }
 
         if (!safepoint_found) {
-          elide_dominated_barrier(access);
+          elide_dominated_barrier(access, mem->is_Mach() ? mem->as_Mach() : nullptr);
         }
       }
     }
   }
 }