--- a/hotspot/src/cpu/x86/vm/c1_CodeStubs_x86.cpp	Tue Apr 05 19:14:03 2011 -0700
+++ b/hotspot/src/cpu/x86/vm/c1_CodeStubs_x86.cpp	Thu Apr 07 09:53:20 2011 -0700
@@ -464,15 +464,19 @@
 #ifndef SERIALGC
 
 void G1PreBarrierStub::emit_code(LIR_Assembler* ce) {
-
-  // At this point we know that marking is in progress
+  // At this point we know that marking is in progress.
+  // If do_load() is true then we have to emit the
+  // load of the previous value; otherwise it has already
+  // been loaded into _pre_val.
 
   __ bind(_entry);
   assert(pre_val()->is_register(), "Precondition.");
 
   Register pre_val_reg = pre_val()->as_register();
 
-  ce->mem2reg(addr(), pre_val(), T_OBJECT, patch_code(), info(), false /*wide*/, false /*unaligned*/);
+  if (do_load()) {
+    ce->mem2reg(addr(), pre_val(), T_OBJECT, patch_code(), info(), false /*wide*/, false /*unaligned*/);
+  }
 
   __ cmpptr(pre_val_reg, (int32_t) NULL_WORD);
   __ jcc(Assembler::equal, _continuation);
@@ -482,6 +486,68 @@
 
 }
 
+void G1UnsafeGetObjSATBBarrierStub::emit_code(LIR_Assembler* ce) {
+  // At this point we know that offset == referent_offset.
+  //
+  // So we might have to emit:
+  //   if (src == null) goto continuation.
+  //
+  // and we definitely have to emit:
+  //   if (klass(src).reference_type == REF_NONE) goto continuation
+  //   if (!marking_active) goto continuation
+  //   if (pre_val == null) goto continuation
+  //   call pre_barrier(pre_val)
+  //   goto continuation
+  //
+  __ bind(_entry);
+
+  assert(src()->is_register(), "sanity");
+  Register src_reg = src()->as_register();
+
+  if (gen_src_check()) {
+    // The original src operand was not a constant.
+    // Generate src == null?
+    __ cmpptr(src_reg, (int32_t) NULL_WORD);
+    __ jcc(Assembler::equal, _continuation);
+  }
+
+  // Generate src->_klass->_reference_type == REF_NONE)?
+  assert(tmp()->is_register(), "sanity");
+  Register tmp_reg = tmp()->as_register();
+
+  __ load_klass(tmp_reg, src_reg);
+
+  Address ref_type_adr(tmp_reg, instanceKlass::reference_type_offset_in_bytes() + sizeof(oopDesc));
+  __ cmpl(ref_type_adr, REF_NONE);
+  __ jcc(Assembler::equal, _continuation);
+
+  // Is marking active?
+  assert(thread()->is_register(), "precondition");
+  Register thread_reg = thread()->as_register();
+
+  Address in_progress(thread_reg, in_bytes(JavaThread::satb_mark_queue_offset() +
+                                       PtrQueue::byte_offset_of_active()));
+
+  if (in_bytes(PtrQueue::byte_width_of_active()) == 4) {
+    __ cmpl(in_progress, 0);
+  } else {
+    assert(in_bytes(PtrQueue::byte_width_of_active()) == 1, "Assumption");
+    __ cmpb(in_progress, 0);
+  }
+  __ jcc(Assembler::equal, _continuation);
+
+  // val == null?
+  assert(val()->is_register(), "Precondition.");
+  Register val_reg = val()->as_register();
+
+  __ cmpptr(val_reg, (int32_t) NULL_WORD);
+  __ jcc(Assembler::equal, _continuation);
+
+  ce->store_parameter(val()->as_register(), 0);
+  __ call(RuntimeAddress(Runtime1::entry_for(Runtime1::g1_pre_barrier_slow_id)));
+  __ jmp(_continuation);
+}
+
 jbyte* G1PostBarrierStub::_byte_map_base = NULL;
 
 jbyte* G1PostBarrierStub::byte_map_base_slow() {