--- old/src/share/vm/c1/c1_LIRGenerator.cpp	2011-03-11 15:51:04.548133000 -0800
+++ new/src/share/vm/c1/c1_LIRGenerator.cpp	2011-03-11 15:51:04.321802000 -0800
@@ -1104,6 +1104,38 @@
   set_no_result(x);
 }
 
+// Examble: ref.get()
+// Combination of LoadField and g1 pre-write barrier
+void LIRGenerator::do_Reference_get(Intrinsic* x) {
+
+  const int referent_offset = java_lang_ref_Reference::referent_offset;
+  guarantee(referent_offset > 0, "referent offset not initialized");
+  
+  assert(x->number_of_arguments() == 1, "wrong type");
+
+  LIRItem reference(x->argument_at(0), this);
+  reference.load_item();
+
+  // need to perform the null check on the reference objecy
+  CodeEmitInfo* info = NULL;
+  if (x->needs_null_check()) {
+    info = state_for(x);
+  }
+
+  LIR_Address* referent_field_adr =
+    new LIR_Address(reference.result(), referent_offset, T_OBJECT);
+
+  LIR_Opr result = rlock_result(x);
+
+  __ load(referent_field_adr, result, info);
+
+  // Register the value in the referent field with the pre-barrier
+  pre_barrier(LIR_OprFact::illegalOpr /* addr_opr */,
+              result /* pre_val */,
+              false  /* do_load */,
+              false  /* patch */,
+              NULL   /* info */);
+}
 
 // Example: object.getClass ()
 void LIRGenerator::do_getClass(Intrinsic* x) {
@@ -1246,13 +1278,14 @@
 
 // Various barriers
 
-void LIRGenerator::pre_barrier(LIR_Opr addr_opr, bool patch,  CodeEmitInfo* info) {
+void LIRGenerator::pre_barrier(LIR_Opr addr_opr, LIR_Opr pre_val,
+                               bool do_load, bool patch, CodeEmitInfo* info) {
   // Do the pre-write barrier, if any.
   switch (_bs->kind()) {
 #ifndef SERIALGC
     case BarrierSet::G1SATBCT:
     case BarrierSet::G1SATBCTLogging:
-      G1SATBCardTableModRef_pre_barrier(addr_opr, patch, info);
+      G1SATBCardTableModRef_pre_barrier(addr_opr, pre_val, do_load, patch, info);
       break;
 #endif // SERIALGC
     case BarrierSet::CardTableModRef:
@@ -1293,9 +1326,8 @@
 ////////////////////////////////////////////////////////////////////////
 #ifndef SERIALGC
 
-void LIRGenerator::G1SATBCardTableModRef_pre_barrier(LIR_Opr addr_opr, bool patch,  CodeEmitInfo* info) {
-  if (G1DisablePreBarrier) return;
-
+void LIRGenerator::G1SATBCardTableModRef_pre_barrier(LIR_Opr addr_opr, LIR_Opr pre_val,
+                                                     bool do_load, bool patch, CodeEmitInfo* info) {
   // First we test whether marking is in progress.
   BasicType flag_type;
   if (in_bytes(PtrQueue::byte_width_of_active()) == 4) {
@@ -1314,26 +1346,40 @@
   // Read the marking-in-progress flag.
   LIR_Opr flag_val = new_register(T_INT);
   __ load(mark_active_flag_addr, flag_val);
+  __ cmp(lir_cond_notEqual, flag_val, LIR_OprFact::intConst(0));
 
-  LIR_PatchCode pre_val_patch_code =
-    patch ? lir_patch_normal : lir_patch_none;
+  LIR_PatchCode pre_val_patch_code = lir_patch_none;
 
-  LIR_Opr pre_val = new_register(T_OBJECT);
+  CodeStub* slow;
 
-  __ cmp(lir_cond_notEqual, flag_val, LIR_OprFact::intConst(0));
-  if (!addr_opr->is_address()) {
-    assert(addr_opr->is_register(), "must be");
-    addr_opr = LIR_OprFact::address(new LIR_Address(addr_opr, T_OBJECT));
+  if (do_load) {
+    assert(pre_val == LIR_OprFact::illegalOpr, "sanity");
+    assert(addr_opr != LIR_OprFact::illegalOpr, "sanity"); 
+    
+    if (patch)
+      pre_val_patch_code = lir_patch_normal;
+    
+    pre_val = new_register(T_OBJECT); 
+    
+    if (!addr_opr->is_address()) {
+      assert(addr_opr->is_register(), "must be");
+      addr_opr = LIR_OprFact::address(new LIR_Address(addr_opr, T_OBJECT));
+    }
+    slow = new G1PreBarrierStub(addr_opr, pre_val, pre_val_patch_code, info);
+  } else {
+    assert(addr_opr == LIR_OprFact::illegalOpr, "sanity");
+    assert(pre_val->is_register(), "must be");
+    assert(pre_val->type() == T_OBJECT, "must be an object");
+    assert(info == NULL, "sanity");
+
+    slow = new G1PreBarrierStub(pre_val);
   }
-  CodeStub* slow = new G1PreBarrierStub(addr_opr, pre_val, pre_val_patch_code,
-                                        info);
+
   __ branch(lir_cond_notEqual, T_INT, slow);
   __ branch_destination(slow->continuation());
 }
 
 void LIRGenerator::G1SATBCardTableModRef_post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val) {
-  if (G1DisablePostBarrier) return;
-
   // If the "new_val" is a constant NULL, no barrier is necessary.
   if (new_val->is_constant() &&
       new_val->as_constant_ptr()->as_jobject() == NULL) return;
@@ -1555,6 +1601,8 @@
   if (is_oop) {
     // Do the pre-write barrier, if any.
     pre_barrier(LIR_OprFact::address(address),
+                LIR_OprFact::illegalOpr /* pre_val */,
+                true /* do_load*/,
                 needs_patching,
                 (info ? new CodeEmitInfo(info) : NULL));
   }
@@ -2656,6 +2704,10 @@
     do_AttemptUpdate(x);
     break;
 
+  case vmIntrinsics::_Reference_get:
+    do_Reference_get(x);
+    break;
+
   default: ShouldNotReachHere(); break;
   }
 }