diff a/src/hotspot/cpu/ppc/gc/shared/barrierSetAssembler_ppc.cpp b/src/hotspot/cpu/ppc/gc/shared/barrierSetAssembler_ppc.cpp
--- a/src/hotspot/cpu/ppc/gc/shared/barrierSetAssembler_ppc.cpp
+++ b/src/hotspot/cpu/ppc/gc/shared/barrierSetAssembler_ppc.cpp
@@ -25,10 +25,11 @@
 
 #include "asm/macroAssembler.inline.hpp"
 #include "classfile/classLoaderData.hpp"
 #include "gc/shared/barrierSetAssembler.hpp"
 #include "gc/shared/barrierSetNMethod.hpp"
+#include "gc/shared/barrierSetRuntime.hpp"
 #include "interpreter/interp_masm.hpp"
 #include "oops/compressedOops.hpp"
 #include "runtime/jniHandles.hpp"
 #include "runtime/sharedRuntime.hpp"
 #include "runtime/stubRoutines.hpp"
@@ -53,17 +54,19 @@
   case T_ARRAY:
   case T_OBJECT: {
     if (UseCompressedOops && in_heap) {
       Register co = tmp1;
       if (val == noreg) {
+        assert(!not_null, "inconsistent access");
         __ li(co, 0);
       } else {
         co = not_null ? __ encode_heap_oop_not_null(tmp1, val) : __ encode_heap_oop(tmp1, val);
       }
       __ stw(co, ind_or_offs, base, tmp2);
     } else {
       if (val == noreg) {
+        assert(!not_null, "inconsistent access");
         val = tmp1;
         __ li(val, 0);
       }
       __ std(val, ind_or_offs, base, tmp2);
     }
@@ -111,10 +114,23 @@
   }
   default: Unimplemented();
   }
 }
 
+void BarrierSetAssembler::flat_field_copy(MacroAssembler* masm, DecoratorSet decorators,
+                                          Register src, Register dst, Register inline_layout_info) {
+  // flat_field_copy implementation is fairly complex, and there are not any
+  // "short-cuts" to be made from asm. What there is, appears to have the same
+  // cost in C++, so just "call_VM_leaf" for now rather than maintain hundreds
+  // of hand-rolled instructions...
+  if (decorators & IS_DEST_UNINITIALIZED) {
+    __ call_VM_leaf(CAST_FROM_FN_PTR(address, BarrierSetRuntime::value_copy_is_dest_uninitialized), src, dst, inline_layout_info);
+  } else {
+    __ call_VM_leaf(CAST_FROM_FN_PTR(address, BarrierSetRuntime::value_copy), src, dst, inline_layout_info);
+  }
+}
+
 // Generic implementation. GCs can provide an optimized one.
 void BarrierSetAssembler::resolve_jobject(MacroAssembler* masm, Register value,
                                           Register tmp1, Register tmp2,
                                           MacroAssembler::PreservationLevel preservation_level) {
   Label done, tagged, weak_tagged, verify;