changeset 2527:089aee76df10

Merge
author asaha
date Wed, 04 May 2011 16:38:05 -0700
parents 5def270bc147 d7cc76ea8d06
children ba2db55ddf8b
files src/os/windows/vm/os_windows.cpp
diffstat 73 files changed, 1674 insertions(+), 496 deletions(-) [+]
line wrap: on
line diff
--- a/.hgignore	Fri Apr 15 09:34:43 2011 -0400
+++ b/.hgignore	Wed May 04 16:38:05 2011 -0700
@@ -5,3 +5,4 @@
 ^src/share/tools/IdealGraphVisualizer/[a-zA-Z0-9]*/build/
 ^src/share/tools/IdealGraphVisualizer/build/
 ^src/share/tools/IdealGraphVisualizer/dist/
+^.hgtip
--- a/make/hotspot_version	Fri Apr 15 09:34:43 2011 -0400
+++ b/make/hotspot_version	Wed May 04 16:38:05 2011 -0700
@@ -35,7 +35,7 @@
 
 HS_MAJOR_VER=21
 HS_MINOR_VER=0
-HS_BUILD_NUMBER=09
+HS_BUILD_NUMBER=10
 
 JDK_MAJOR_VER=1
 JDK_MINOR_VER=7
--- a/src/cpu/sparc/vm/assembler_sparc.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/assembler_sparc.cpp	Wed May 04 16:38:05 2011 -0700
@@ -4257,34 +4257,14 @@
 ///////////////////////////////////////////////////////////////////////////////////
 #ifndef SERIALGC
 
-static uint num_stores = 0;
-static uint num_null_pre_stores = 0;
-
-static void count_null_pre_vals(void* pre_val) {
-  num_stores++;
-  if (pre_val == NULL) num_null_pre_stores++;
-  if ((num_stores % 1000000) == 0) {
-    tty->print_cr(UINT32_FORMAT " stores, " UINT32_FORMAT " (%5.2f%%) with null pre-vals.",
-                  num_stores, num_null_pre_stores,
-                  100.0*(float)num_null_pre_stores/(float)num_stores);
-  }
-}
-
-static address satb_log_enqueue_with_frame = 0;
-static u_char* satb_log_enqueue_with_frame_end = 0;
-
-static address satb_log_enqueue_frameless = 0;
-static u_char* satb_log_enqueue_frameless_end = 0;
+static address satb_log_enqueue_with_frame = NULL;
+static u_char* satb_log_enqueue_with_frame_end = NULL;
+
+static address satb_log_enqueue_frameless = NULL;
+static u_char* satb_log_enqueue_frameless_end = NULL;
 
 static int EnqueueCodeSize = 128 DEBUG_ONLY( + 256); // Instructions?
 
-// The calls to this don't work.  We'd need to do a fair amount of work to
-// make it work.
-static void check_index(int ind) {
-  assert(0 <= ind && ind <= 64*K && ((ind % oopSize) == 0),
-         "Invariants.");
-}
-
 static void generate_satb_log_enqueue(bool with_frame) {
   BufferBlob* bb = BufferBlob::create("enqueue_with_frame", EnqueueCodeSize);
   CodeBuffer buf(bb);
@@ -4388,13 +4368,27 @@
   }
 }
 
-void MacroAssembler::g1_write_barrier_pre(Register obj, Register index, int offset, Register tmp, bool preserve_o_regs) {
-  assert(offset == 0 || index == noreg, "choose one");
-
-  if (G1DisablePreBarrier) return;
-  // satb_log_barrier(tmp, obj, offset, preserve_o_regs);
+void MacroAssembler::g1_write_barrier_pre(Register obj,
+                                          Register index,
+                                          int offset,
+                                          Register pre_val,
+                                          Register tmp,
+                                          bool preserve_o_regs) {
   Label filtered;
-  // satb_log_barrier_work0(tmp, filtered);
+
+  if (obj == noreg) {
+    // We are not loading the previous value so make
+    // sure that we don't trash the value in pre_val
+    // with the code below.
+    assert_different_registers(pre_val, tmp);
+  } else {
+    // We will be loading the previous value
+    // in this code so...
+    assert(offset == 0 || index == noreg, "choose one");
+    assert(pre_val == noreg, "check this code");
+  }
+
+  // Is marking active?
   if (in_bytes(PtrQueue::byte_width_of_active()) == 4) {
     ld(G2,
        in_bytes(JavaThread::satb_mark_queue_offset() +
@@ -4413,61 +4407,46 @@
   br_on_reg_cond(rc_z, /*annul*/false, Assembler::pt, tmp, filtered);
   delayed() -> nop();
 
-  // satb_log_barrier_work1(tmp, offset);
-  if (index == noreg) {
-    if (Assembler::is_simm13(offset)) {
-      load_heap_oop(obj, offset, tmp);
+  // Do we need to load the previous value?
+  if (obj != noreg) {
+    // Load the previous value...
+    if (index == noreg) {
+      if (Assembler::is_simm13(offset)) {
+        load_heap_oop(obj, offset, tmp);
+      } else {
+        set(offset, tmp);
+        load_heap_oop(obj, tmp, tmp);
+      }
     } else {
-      set(offset, tmp);
-      load_heap_oop(obj, tmp, tmp);
+      load_heap_oop(obj, index, tmp);
     }
-  } else {
-    load_heap_oop(obj, index, tmp);
+    // Previous value has been loaded into tmp
+    pre_val = tmp;
   }
 
-  // satb_log_barrier_work2(obj, tmp, offset);
-
-  // satb_log_barrier_work3(tmp, filtered, preserve_o_regs);
-
-  const Register pre_val = tmp;
-
-  if (G1SATBBarrierPrintNullPreVals) {
-    save_frame(0);
-    mov(pre_val, O0);
-    // Save G-regs that target may use.
-    mov(G1, L1);
-    mov(G2, L2);
-    mov(G3, L3);
-    mov(G4, L4);
-    mov(G5, L5);
-    call(CAST_FROM_FN_PTR(address, &count_null_pre_vals));
-    delayed()->nop();
-    // Restore G-regs that target may have used.
-    mov(L1, G1);
-    mov(L2, G2);
-    mov(L3, G3);
-    mov(L4, G4);
-    mov(L5, G5);
-    restore(G0, G0, G0);
-  }
-
+  assert(pre_val != noreg, "must have a real register");
+
+  // Is the previous value null?
   // Check on whether to annul.
   br_on_reg_cond(rc_z, /*annul*/false, Assembler::pt, pre_val, filtered);
   delayed() -> nop();
 
   // OK, it's not filtered, so we'll need to call enqueue.  In the normal
-  // case, pre_val will be a scratch G-reg, but there's some cases in which
-  // it's an O-reg.  In the first case, do a normal call.  In the latter,
-  // do a save here and call the frameless version.
+  // case, pre_val will be a scratch G-reg, but there are some cases in
+  // which it's an O-reg.  In the first case, do a normal call.  In the
+  // latter, do a save here and call the frameless version.
 
   guarantee(pre_val->is_global() || pre_val->is_out(),
             "Or we need to think harder.");
+
   if (pre_val->is_global() && !preserve_o_regs) {
-    generate_satb_log_enqueue_if_necessary(true); // with frame.
+    generate_satb_log_enqueue_if_necessary(true); // with frame
+
     call(satb_log_enqueue_with_frame);
     delayed()->mov(pre_val, O0);
   } else {
-    generate_satb_log_enqueue_if_necessary(false); // with frameless.
+    generate_satb_log_enqueue_if_necessary(false); // frameless
+
     save_frame(0);
     call(satb_log_enqueue_frameless);
     delayed()->mov(pre_val->after_save(), O0);
@@ -4614,7 +4593,6 @@
   MacroAssembler* post_filter_masm = this;
 
   if (new_val == G0) return;
-  if (G1DisablePostBarrier) return;
 
   G1SATBCardTableModRefBS* bs = (G1SATBCardTableModRefBS*) Universe::heap()->barrier_set();
   assert(bs->kind() == BarrierSet::G1SATBCT ||
@@ -4626,6 +4604,7 @@
 #else
     srl(tmp, HeapRegion::LogOfHRGrainBytes, tmp);
 #endif
+
     if (G1PrintCTFilterStats) {
       guarantee(tmp->is_global(), "Or stats won't work...");
       // This is a sleazy hack: I'm temporarily hijacking G2, which I
--- a/src/cpu/sparc/vm/assembler_sparc.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/assembler_sparc.hpp	Wed May 04 16:38:05 2011 -0700
@@ -2210,15 +2210,11 @@
   void card_write_barrier_post(Register store_addr, Register new_val, Register tmp);
 
 #ifndef SERIALGC
-  // Array store and offset
-  void g1_write_barrier_pre(Register obj, Register index, int offset, Register tmp, bool preserve_o_regs);
-
+  // General G1 pre-barrier generator.
+  void g1_write_barrier_pre(Register obj, Register index, int offset, Register pre_val, Register tmp, bool preserve_o_regs);
+
+  // General G1 post-barrier generator
   void g1_write_barrier_post(Register store_addr, Register new_val, Register tmp);
-
-  // May do filtering, depending on the boolean arguments.
-  void g1_card_table_write(jbyte* byte_map_base,
-                           Register tmp, Register obj, Register new_val,
-                           bool region_filter, bool null_filter);
 #endif // SERIALGC
 
   // pushes double TOS element of FPU stack on CPU stack; pops from FPU stack
--- a/src/cpu/sparc/vm/c1_CodeStubs_sparc.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/c1_CodeStubs_sparc.cpp	Wed May 04 16:38:05 2011 -0700
@@ -408,13 +408,20 @@
 #ifndef SERIALGC
 
 void G1PreBarrierStub::emit_code(LIR_Assembler* ce) {
+  // 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*/);
+  }
+
   if (__ is_in_wdisp16_range(_continuation)) {
     __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
                       pre_val_reg, _continuation);
@@ -431,6 +438,96 @@
 
 }
 
+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?
+    if (__ is_in_wdisp16_range(_continuation)) {
+      __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                        src_reg, _continuation);
+    } else {
+      __ cmp(src_reg, G0);
+      __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+    }
+    __ delayed()->nop();
+  }
+
+  // Generate src->_klass->_reference_type() == REF_NONE)?
+  assert(tmp()->is_register(), "sanity");
+  Register tmp_reg = tmp()->as_register();
+
+  __ load_klass(src_reg, tmp_reg);
+
+  Address ref_type_adr(tmp_reg, instanceKlass::reference_type_offset_in_bytes() + sizeof(oopDesc));
+  __ ld(ref_type_adr, tmp_reg);
+
+  if (__ is_in_wdisp16_range(_continuation)) {
+    __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                      tmp_reg, _continuation);
+  } else {
+    __ cmp(tmp_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+  }
+  __ delayed()->nop();
+
+  // Is marking active?
+  assert(thread()->is_register(), "precondition");
+  Register thread_reg = thread()->as_pointer_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) {
+    __ ld(in_progress, tmp_reg);
+  } else {
+    assert(in_bytes(PtrQueue::byte_width_of_active()) == 1, "Assumption");
+    __ ldsb(in_progress, tmp_reg);
+  }
+  if (__ is_in_wdisp16_range(_continuation)) {
+    __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                      tmp_reg, _continuation);
+  } else {
+    __ cmp(tmp_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+  }
+  __ delayed()->nop();
+
+  // val == null?
+  assert(val()->is_register(), "Precondition.");
+  Register val_reg = val()->as_register();
+
+  if (__ is_in_wdisp16_range(_continuation)) {
+    __ br_on_reg_cond(Assembler::rc_z, /*annul*/false, Assembler::pt,
+                      val_reg, _continuation);
+  } else {
+    __ cmp(val_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pt, _continuation);
+  }
+  __ delayed()->nop();
+
+  __ call(Runtime1::entry_for(Runtime1::Runtime1::g1_pre_barrier_slow_id));
+  __ delayed()->mov(val_reg, G4);
+  __ br(Assembler::always, false, Assembler::pt, _continuation);
+  __ delayed()->nop();
+}
+
 jbyte* G1PostBarrierStub::_byte_map_base = NULL;
 
 jbyte* G1PostBarrierStub::byte_map_base_slow() {
--- a/src/cpu/sparc/vm/c1_LIRGenerator_sparc.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/c1_LIRGenerator_sparc.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -387,7 +387,8 @@
 
   if (obj_store) {
     // Needs GC write barriers.
-    pre_barrier(LIR_OprFact::address(array_addr), false, NULL);
+    pre_barrier(LIR_OprFact::address(array_addr), LIR_OprFact::illegalOpr /* pre_val */,
+                true /* do_load */, false /* patch */, NULL);
   }
   __ move(value.result(), array_addr, null_check_info);
   if (obj_store) {
@@ -687,7 +688,8 @@
   __ add(obj.result(), offset.result(), addr);
 
   if (type == objectType) {  // Write-barrier needed for Object fields.
-    pre_barrier(addr, false, NULL);
+    pre_barrier(addr, LIR_OprFact::illegalOpr /* pre_val */,
+                true /* do_load */, false /* patch */, NULL);
   }
 
   if (type == objectType)
@@ -1187,7 +1189,8 @@
       }
 
       if (is_obj) {
-        pre_barrier(LIR_OprFact::address(addr), false, NULL);
+        pre_barrier(LIR_OprFact::address(addr), LIR_OprFact::illegalOpr /* pre_val */,
+                    true /* do_load */, false /* patch */, NULL);
         // _bs->c1_write_barrier_pre(this, LIR_OprFact::address(addr));
       }
       __ move(data, addr);
--- a/src/cpu/sparc/vm/cppInterpreter_sparc.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/cppInterpreter_sparc.cpp	Wed May 04 16:38:05 2011 -0700
@@ -551,6 +551,26 @@
   return NULL;
 }
 
+address InterpreterGenerator::generate_Reference_get_entry(void) {
+#ifndef SERIALGC
+  if (UseG1GC) {
+    // We need to generate have a routine that generates code to:
+    //   * load the value in the referent field
+    //   * passes that value to the pre-barrier.
+    //
+    // In the case of G1 this will record the value of the
+    // referent in an SATB buffer if marking is active.
+    // This will cause concurrent marking to mark the referent
+    // field as live.
+    Unimplemented();
+  }
+#endif // SERIALGC
+
+  // If G1 is not enabled then attempt to go through the accessor entry point
+  // Reference.get is an accessor
+  return generate_accessor_entry();
+}
+
 //
 // Interpreter stub for calling a native method. (C++ interpreter)
 // This sets up a somewhat different looking stack for calling the native method
--- a/src/cpu/sparc/vm/interpreterGenerator_sparc.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/interpreterGenerator_sparc.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,6 +36,7 @@
   address generate_math_entry(AbstractInterpreter::MethodKind kind);
   address generate_empty_entry(void);
   address generate_accessor_entry(void);
+  address generate_Reference_get_entry(void);
   void lock_method(void);
   void save_native_result(void);
   void restore_native_result(void);
--- a/src/cpu/sparc/vm/interpreter_sparc.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/interpreter_sparc.cpp	Wed May 04 16:38:05 2011 -0700
@@ -407,6 +407,8 @@
     case Interpreter::java_lang_math_abs     :                                                                             break;
     case Interpreter::java_lang_math_log     :                                                                             break;
     case Interpreter::java_lang_math_log10   :                                                                             break;
+    case Interpreter::java_lang_ref_reference_get
+                                             : entry_point = ((InterpreterGenerator*)this)->generate_Reference_get_entry(); break;
     default                                  : ShouldNotReachHere();                                                       break;
   }
 
--- a/src/cpu/sparc/vm/templateInterpreter_sparc.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/templateInterpreter_sparc.cpp	Wed May 04 16:38:05 2011 -0700
@@ -763,6 +763,87 @@
   return NULL;
 }
 
+// Method entry for java.lang.ref.Reference.get.
+address InterpreterGenerator::generate_Reference_get_entry(void) {
+#ifndef SERIALGC
+  // Code: _aload_0, _getfield, _areturn
+  // parameter size = 1
+  //
+  // The code that gets generated by this routine is split into 2 parts:
+  //    1. The "intrinsified" code for G1 (or any SATB based GC),
+  //    2. The slow path - which is an expansion of the regular method entry.
+  //
+  // Notes:-
+  // * In the G1 code we do not check whether we need to block for
+  //   a safepoint. If G1 is enabled then we must execute the specialized
+  //   code for Reference.get (except when the Reference object is null)
+  //   so that we can log the value in the referent field with an SATB
+  //   update buffer.
+  //   If the code for the getfield template is modified so that the
+  //   G1 pre-barrier code is executed when the current method is
+  //   Reference.get() then going through the normal method entry
+  //   will be fine.
+  // * The G1 code can, however, check the receiver object (the instance
+  //   of java.lang.Reference) and jump to the slow path if null. If the
+  //   Reference object is null then we obviously cannot fetch the referent
+  //   and so we don't need to call the G1 pre-barrier. Thus we can use the
+  //   regular method entry code to generate the NPE.
+  //
+  // This code is based on generate_accessor_enty.
+
+  address entry = __ pc();
+
+  const int referent_offset = java_lang_ref_Reference::referent_offset;
+  guarantee(referent_offset > 0, "referent offset not initialized");
+
+  if (UseG1GC) {
+     Label slow_path;
+
+    // In the G1 code we don't check if we need to reach a safepoint. We
+    // continue and the thread will safepoint at the next bytecode dispatch.
+
+    // Check if local 0 != NULL
+    // If the receiver is null then it is OK to jump to the slow path.
+    __ ld_ptr(Gargs, G0, Otos_i ); // get local 0
+    __ tst(Otos_i);  // check if local 0 == NULL and go the slow path
+    __ brx(Assembler::zero, false, Assembler::pn, slow_path);
+    __ delayed()->nop();
+
+
+    // Load the value of the referent field.
+    if (Assembler::is_simm13(referent_offset)) {
+      __ load_heap_oop(Otos_i, referent_offset, Otos_i);
+    } else {
+      __ set(referent_offset, G3_scratch);
+      __ load_heap_oop(Otos_i, G3_scratch, Otos_i);
+    }
+
+    // Generate the G1 pre-barrier code to log the value of
+    // the referent field in an SATB buffer. Note with
+    // these parameters the pre-barrier does not generate
+    // the load of the previous value
+
+    __ g1_write_barrier_pre(noreg /* obj */, noreg /* index */, 0 /* offset */,
+                            Otos_i /* pre_val */,
+                            G3_scratch /* tmp */,
+                            true /* preserve_o_regs */);
+
+    // _areturn
+    __ retl();                      // return from leaf routine
+    __ delayed()->mov(O5_savedSP, SP);
+
+    // Generate regular method entry
+    __ bind(slow_path);
+    (void) generate_normal_entry(false);
+    return entry;
+  }
+#endif // SERIALGC
+
+  // If G1 is not enabled then attempt to go through the accessor entry point
+  // Reference.get is an accessor
+  return generate_accessor_entry();
+}
+
 //
 // Interpreter stub for calling a native method. (asm interpreter)
 // This sets up a somewhat different looking stack for calling the native method
--- a/src/cpu/sparc/vm/templateTable_sparc.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/sparc/vm/templateTable_sparc.cpp	Wed May 04 16:38:05 2011 -0700
@@ -57,7 +57,11 @@
     case BarrierSet::G1SATBCT:
     case BarrierSet::G1SATBCTLogging:
       {
-        __ g1_write_barrier_pre( base, index, offset, tmp, /*preserve_o_regs*/true);
+        // Load and record the previous value.
+        __ g1_write_barrier_pre(base, index, offset,
+                                noreg /* pre_val */,
+                                tmp, true /*preserve_o_regs*/);
+
         if (index == noreg ) {
           assert(Assembler::is_simm13(offset), "fix this code");
           __ store_heap_oop(val, base, offset);
--- a/src/cpu/x86/vm/assembler_x86.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/assembler_x86.cpp	Wed May 04 16:38:05 2011 -0700
@@ -6902,26 +6902,39 @@
 #ifndef SERIALGC
 
 void MacroAssembler::g1_write_barrier_pre(Register obj,
-#ifndef _LP64
+                                          Register pre_val,
                                           Register thread,
-#endif
                                           Register tmp,
-                                          Register tmp2,
-                                          bool tosca_live) {
-  LP64_ONLY(Register thread = r15_thread;)
+                                          bool tosca_live,
+                                          bool expand_call) {
+
+  // If expand_call is true then we expand the call_VM_leaf macro
+  // directly to skip generating the check by
+  // InterpreterMacroAssembler::call_VM_leaf_base that checks _last_sp.
+
+#ifdef _LP64
+  assert(thread == r15_thread, "must be");
+#endif // _LP64
+
+  Label done;
+  Label runtime;
+
+  assert(pre_val != noreg, "check this code");
+
+  if (obj != noreg) {
+    assert_different_registers(obj, pre_val, tmp);
+    assert(pre_val != rax, "check this code");
+  }
+
   Address in_progress(thread, in_bytes(JavaThread::satb_mark_queue_offset() +
                                        PtrQueue::byte_offset_of_active()));
-
   Address index(thread, in_bytes(JavaThread::satb_mark_queue_offset() +
                                        PtrQueue::byte_offset_of_index()));
   Address buffer(thread, in_bytes(JavaThread::satb_mark_queue_offset() +
                                        PtrQueue::byte_offset_of_buf()));
 
 
-  Label done;
-  Label runtime;
-
-  // if (!marking_in_progress) goto done;
+  // Is marking active?
   if (in_bytes(PtrQueue::byte_width_of_active()) == 4) {
     cmpl(in_progress, 0);
   } else {
@@ -6930,65 +6943,92 @@
   }
   jcc(Assembler::equal, done);
 
-  // if (x.f == NULL) goto done;
-#ifdef _LP64
-  load_heap_oop(tmp2, Address(obj, 0));
-#else
-  movptr(tmp2, Address(obj, 0));
-#endif
-  cmpptr(tmp2, (int32_t) NULL_WORD);
+  // Do we need to load the previous value?
+  if (obj != noreg) {
+    load_heap_oop(pre_val, Address(obj, 0));
+  }
+
+  // Is the previous value null?
+  cmpptr(pre_val, (int32_t) NULL_WORD);
   jcc(Assembler::equal, done);
 
   // Can we store original value in the thread's buffer?
-
-#ifdef _LP64
-  movslq(tmp, index);
-  cmpq(tmp, 0);
-#else
-  cmpl(index, 0);
-#endif
-  jcc(Assembler::equal, runtime);
-#ifdef _LP64
-  subq(tmp, wordSize);
-  movl(index, tmp);
-  addq(tmp, buffer);
-#else
-  subl(index, wordSize);
-  movl(tmp, buffer);
-  addl(tmp, index);
-#endif
-  movptr(Address(tmp, 0), tmp2);
+  // Is index == 0?
+  // (The index field is typed as size_t.)
+
+  movptr(tmp, index);                   // tmp := *index_adr
+  cmpptr(tmp, 0);                       // tmp == 0?
+  jcc(Assembler::equal, runtime);       // If yes, goto runtime
+
+  subptr(tmp, wordSize);                // tmp := tmp - wordSize
+  movptr(index, tmp);                   // *index_adr := tmp
+  addptr(tmp, buffer);                  // tmp := tmp + *buffer_adr
+
+  // Record the previous value
+  movptr(Address(tmp, 0), pre_val);
   jmp(done);
+
   bind(runtime);
   // save the live input values
   if(tosca_live) push(rax);
-  push(obj);
-#ifdef _LP64
-  call_VM_leaf(CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_pre), tmp2, r15_thread);
-#else
-  push(thread);
-  call_VM_leaf(CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_pre), tmp2, thread);
-  pop(thread);
-#endif
-  pop(obj);
+
+  if (obj != noreg && obj != rax)
+    push(obj);
+
+  if (pre_val != rax)
+    push(pre_val);
+
+  // Calling the runtime using the regular call_VM_leaf mechanism generates
+  // code (generated by InterpreterMacroAssember::call_VM_leaf_base)
+  // that checks that the *(ebp+frame::interpreter_frame_last_sp) == NULL.
+  //
+  // If we care generating the pre-barrier without a frame (e.g. in the
+  // intrinsified Reference.get() routine) then ebp might be pointing to
+  // the caller frame and so this check will most likely fail at runtime.
+  //
+  // Expanding the call directly bypasses the generation of the check.
+  // So when we do not have have a full interpreter frame on the stack
+  // expand_call should be passed true.
+
+  NOT_LP64( push(thread); )
+
+  if (expand_call) {
+    LP64_ONLY( assert(pre_val != c_rarg1, "smashed arg"); )
+    pass_arg1(this, thread);
+    pass_arg0(this, pre_val);
+    MacroAssembler::call_VM_leaf_base(CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_pre), 2);
+  } else {
+    call_VM_leaf(CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_pre), pre_val, thread);
+  }
+
+  NOT_LP64( pop(thread); )
+
+  // save the live input values
+  if (pre_val != rax)
+    pop(pre_val);
+
+  if (obj != noreg && obj != rax)
+    pop(obj);
+
   if(tosca_live) pop(rax);
+
   bind(done);
-
 }
 
 void MacroAssembler::g1_write_barrier_post(Register store_addr,
                                            Register new_val,
-#ifndef _LP64
                                            Register thread,
-#endif
                                            Register tmp,
                                            Register tmp2) {
-
-  LP64_ONLY(Register thread = r15_thread;)
+#ifdef _LP64
+  assert(thread == r15_thread, "must be");
+#endif // _LP64
+
   Address queue_index(thread, in_bytes(JavaThread::dirty_card_queue_offset() +
                                        PtrQueue::byte_offset_of_index()));
   Address buffer(thread, in_bytes(JavaThread::dirty_card_queue_offset() +
                                        PtrQueue::byte_offset_of_buf()));
+
   BarrierSet* bs = Universe::heap()->barrier_set();
   CardTableModRefBS* ct = (CardTableModRefBS*)bs;
   Label done;
@@ -7067,7 +7107,6 @@
   pop(store_addr);
 
   bind(done);
-
 }
 
 #endif // SERIALGC
--- a/src/cpu/x86/vm/assembler_x86.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/assembler_x86.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1453,6 +1453,7 @@
 class MacroAssembler: public Assembler {
   friend class LIR_Assembler;
   friend class Runtime1;      // as_Address()
+
  protected:
 
   Address as_Address(AddressLiteral adr);
@@ -1674,21 +1675,22 @@
   void store_check(Register obj);                // store check for obj - register is destroyed afterwards
   void store_check(Register obj, Address dst);   // same as above, dst is exact store location (reg. is destroyed)
 
+#ifndef SERIALGC
+
   void g1_write_barrier_pre(Register obj,
-#ifndef _LP64
+                            Register pre_val,
                             Register thread,
-#endif
                             Register tmp,
-                            Register tmp2,
-                            bool     tosca_live);
+                            bool tosca_live,
+                            bool expand_call);
+
   void g1_write_barrier_post(Register store_addr,
                              Register new_val,
-#ifndef _LP64
                              Register thread,
-#endif
                              Register tmp,
                              Register tmp2);
 
+#endif // SERIALGC
 
   // split store_check(Register obj) to enhance instruction interleaving
   void store_check_part_1(Register obj);
--- a/src/cpu/x86/vm/c1_CodeStubs_x86.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/c1_CodeStubs_x86.cpp	Wed May 04 16:38:05 2011 -0700
@@ -466,15 +466,19 @@
 #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);
@@ -484,6 +488,68 @@
 
 }
 
+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_pointer_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() {
--- a/src/cpu/x86/vm/c1_LIRGenerator_x86.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/c1_LIRGenerator_x86.cpp	Wed May 04 16:38:05 2011 -0700
@@ -326,7 +326,8 @@
 
   if (obj_store) {
     // Needs GC write barriers.
-    pre_barrier(LIR_OprFact::address(array_addr), false, NULL);
+    pre_barrier(LIR_OprFact::address(array_addr), LIR_OprFact::illegalOpr /* pre_val */,
+                true /* do_load */, false /* patch */, NULL);
     __ move(value.result(), array_addr, null_check_info);
     // Seems to be a precise
     post_barrier(LIR_OprFact::address(array_addr), value.result());
@@ -794,7 +795,8 @@
 
   if (type == objectType) {  // Write-barrier needed for Object fields.
     // Do the pre-write barrier, if any.
-    pre_barrier(addr, false, NULL);
+    pre_barrier(addr, LIR_OprFact::illegalOpr /* pre_val */,
+                true /* do_load */, false /* patch */, NULL);
   }
 
   LIR_Opr ill = LIR_OprFact::illegalOpr;  // for convenience
@@ -1339,7 +1341,8 @@
     bool is_obj = (type == T_ARRAY || type == T_OBJECT);
     if (is_obj) {
       // Do the pre-write barrier, if any.
-      pre_barrier(LIR_OprFact::address(addr), false, NULL);
+      pre_barrier(LIR_OprFact::address(addr), LIR_OprFact::illegalOpr /* pre_val */,
+                  true /* do_load */, false /* patch */, NULL);
       __ move(data, addr);
       assert(src->is_register(), "must be register");
       // Seems to be a precise address
--- a/src/cpu/x86/vm/cppInterpreterGenerator_x86.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/cppInterpreterGenerator_x86.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -34,6 +34,7 @@
   address generate_math_entry(AbstractInterpreter::MethodKind kind);
   address generate_empty_entry(void);
   address generate_accessor_entry(void);
+  address generate_Reference_get_entry(void);
   void lock_method(void);
   void generate_stack_overflow_check(void);
 
--- a/src/cpu/x86/vm/cppInterpreter_x86.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/cppInterpreter_x86.cpp	Wed May 04 16:38:05 2011 -0700
@@ -936,6 +936,26 @@
 
 }
 
+address InterpreterGenerator::generate_Reference_get_entry(void) {
+#ifndef SERIALGC
+  if (UseG1GC) {
+    // We need to generate have a routine that generates code to:
+    //   * load the value in the referent field
+    //   * passes that value to the pre-barrier.
+    //
+    // In the case of G1 this will record the value of the
+    // referent in an SATB buffer if marking is active.
+    // This will cause concurrent marking to mark the referent
+    // field as live.
+    Unimplemented();
+  }
+#endif // SERIALGC
+
+  // If G1 is not enabled then attempt to go through the accessor entry point
+  // Reference.get is an accessor
+  return generate_accessor_entry();
+}
+
 //
 // C++ Interpreter stub for calling a native method.
 // This sets up a somewhat different looking stack for calling the native method
@@ -2210,6 +2230,8 @@
     case Interpreter::java_lang_math_log     : // fall thru
     case Interpreter::java_lang_math_log10   : // fall thru
     case Interpreter::java_lang_math_sqrt    : entry_point = ((InterpreterGenerator*)this)->generate_math_entry(kind);     break;
+    case Interpreter::java_lang_ref_reference_get
+                                             : entry_point = ((InterpreterGenerator*)this)->generate_Reference_get_entry(); break;
     default                                  : ShouldNotReachHere();                                                       break;
   }
 
--- a/src/cpu/x86/vm/interpreterGenerator_x86.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/interpreterGenerator_x86.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -39,6 +39,7 @@
   address generate_math_entry(AbstractInterpreter::MethodKind kind);
   address generate_empty_entry(void);
   address generate_accessor_entry(void);
+  address generate_Reference_get_entry();
   void lock_method(void);
   void generate_stack_overflow_check(void);
 
--- a/src/cpu/x86/vm/templateInterpreter_x86_32.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/templateInterpreter_x86_32.cpp	Wed May 04 16:38:05 2011 -0700
@@ -776,6 +776,98 @@
 
 }
 
+// Method entry for java.lang.ref.Reference.get.
+address InterpreterGenerator::generate_Reference_get_entry(void) {
+#ifndef SERIALGC
+  // Code: _aload_0, _getfield, _areturn
+  // parameter size = 1
+  //
+  // The code that gets generated by this routine is split into 2 parts:
+  //    1. The "intrinsified" code for G1 (or any SATB based GC),
+  //    2. The slow path - which is an expansion of the regular method entry.
+  //
+  // Notes:-
+  // * In the G1 code we do not check whether we need to block for
+  //   a safepoint. If G1 is enabled then we must execute the specialized
+  //   code for Reference.get (except when the Reference object is null)
+  //   so that we can log the value in the referent field with an SATB
+  //   update buffer.
+  //   If the code for the getfield template is modified so that the
+  //   G1 pre-barrier code is executed when the current method is
+  //   Reference.get() then going through the normal method entry
+  //   will be fine.
+  // * The G1 code below can, however, check the receiver object (the instance
+  //   of java.lang.Reference) and jump to the slow path if null. If the
+  //   Reference object is null then we obviously cannot fetch the referent
+  //   and so we don't need to call the G1 pre-barrier. Thus we can use the
+  //   regular method entry code to generate the NPE.
+  //
+  // This code is based on generate_accessor_enty.
+
+  // rbx,: methodOop
+  // rcx: receiver (preserve for slow entry into asm interpreter)
+
+  // rsi: senderSP must preserved for slow path, set SP to it on fast path
+
+  address entry = __ pc();
+
+  const int referent_offset = java_lang_ref_Reference::referent_offset;
+  guarantee(referent_offset > 0, "referent offset not initialized");
+
+  if (UseG1GC) {
+    Label slow_path;
+
+    // Check if local 0 != NULL
+    // If the receiver is null then it is OK to jump to the slow path.
+    __ movptr(rax, Address(rsp, wordSize));
+    __ testptr(rax, rax);
+    __ jcc(Assembler::zero, slow_path);
+
+    // rax: local 0 (must be preserved across the G1 barrier call)
+    //
+    // rbx: method (at this point it's scratch)
+    // rcx: receiver (at this point it's scratch)
+    // rdx: scratch
+    // rdi: scratch
+    //
+    // rsi: sender sp
+
+    // Preserve the sender sp in case the pre-barrier
+    // calls the runtime
+    __ push(rsi);
+
+    // Load the value of the referent field.
+    const Address field_address(rax, referent_offset);
+    __ movptr(rax, field_address);
+
+    // Generate the G1 pre-barrier code to log the value of
+    // the referent field in an SATB buffer.
+    __ get_thread(rcx);
+    __ g1_write_barrier_pre(noreg /* obj */,
+                            rax /* pre_val */,
+                            rcx /* thread */,
+                            rbx /* tmp */,
+                            true /* tosca_save */,
+                            true /* expand_call */);
+
+    // _areturn
+    __ pop(rsi);                // get sender sp
+    __ pop(rdi);                // get return address
+    __ mov(rsp, rsi);           // set sp to sender sp
+    __ jmp(rdi);
+
+    __ bind(slow_path);
+    (void) generate_normal_entry(false);
+
+    return entry;
+  }
+#endif // SERIALGC
+
+  // If G1 is not enabled then attempt to go through the accessor entry point
+  // Reference.get is an accessor
+  return generate_accessor_entry();
+}
+
 //
 // Interpreter stub for calling a native method. (asm interpreter)
 // This sets up a somewhat different looking stack for calling the native method
@@ -1444,6 +1536,8 @@
     case Interpreter::java_lang_math_log     : // fall thru
     case Interpreter::java_lang_math_log10   : // fall thru
     case Interpreter::java_lang_math_sqrt    : entry_point = ((InterpreterGenerator*)this)->generate_math_entry(kind);     break;
+    case Interpreter::java_lang_ref_reference_get
+                                             : entry_point = ((InterpreterGenerator*)this)->generate_Reference_get_entry(); break;
     default                                  : ShouldNotReachHere();                                                       break;
   }
 
--- a/src/cpu/x86/vm/templateInterpreter_x86_64.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/templateInterpreter_x86_64.cpp	Wed May 04 16:38:05 2011 -0700
@@ -757,6 +757,95 @@
   return entry_point;
 }
 
+// Method entry for java.lang.ref.Reference.get.
+address InterpreterGenerator::generate_Reference_get_entry(void) {
+#ifndef SERIALGC
+  // Code: _aload_0, _getfield, _areturn
+  // parameter size = 1
+  //
+  // The code that gets generated by this routine is split into 2 parts:
+  //    1. The "intrinsified" code for G1 (or any SATB based GC),
+  //    2. The slow path - which is an expansion of the regular method entry.
+  //
+  // Notes:-
+  // * In the G1 code we do not check whether we need to block for
+  //   a safepoint. If G1 is enabled then we must execute the specialized
+  //   code for Reference.get (except when the Reference object is null)
+  //   so that we can log the value in the referent field with an SATB
+  //   update buffer.
+  //   If the code for the getfield template is modified so that the
+  //   G1 pre-barrier code is executed when the current method is
+  //   Reference.get() then going through the normal method entry
+  //   will be fine.
+  // * The G1 code can, however, check the receiver object (the instance
+  //   of java.lang.Reference) and jump to the slow path if null. If the
+  //   Reference object is null then we obviously cannot fetch the referent
+  //   and so we don't need to call the G1 pre-barrier. Thus we can use the
+  //   regular method entry code to generate the NPE.
+  //
+  // This code is based on generate_accessor_enty.
+  //
+  // rbx: methodOop
+
+  // r13: senderSP must preserve for slow path, set SP to it on fast path
+
+  address entry = __ pc();
+
+  const int referent_offset = java_lang_ref_Reference::referent_offset;
+  guarantee(referent_offset > 0, "referent offset not initialized");
+
+  if (UseG1GC) {
+    Label slow_path;
+    // rbx: method
+
+    // Check if local 0 != NULL
+    // If the receiver is null then it is OK to jump to the slow path.
+    __ movptr(rax, Address(rsp, wordSize));
+
+    __ testptr(rax, rax);
+    __ jcc(Assembler::zero, slow_path);
+
+    // rax: local 0
+    // rbx: method (but can be used as scratch now)
+    // rdx: scratch
+    // rdi: scratch
+
+    // Generate the G1 pre-barrier code to log the value of
+    // the referent field in an SATB buffer.
+
+    // Load the value of the referent field.
+    const Address field_address(rax, referent_offset);
+    __ load_heap_oop(rax, field_address);
+
+    // Generate the G1 pre-barrier code to log the value of
+    // the referent field in an SATB buffer.
+    __ g1_write_barrier_pre(noreg /* obj */,
+                            rax /* pre_val */,
+                            r15_thread /* thread */,
+                            rbx /* tmp */,
+                            true /* tosca_live */,
+                            true /* expand_call */);
+
+    // _areturn
+    __ pop(rdi);                // get return address
+    __ mov(rsp, r13);           // set sp to sender sp
+    __ jmp(rdi);
+    __ ret(0);
+
+    // generate a vanilla interpreter entry as the slow path
+    __ bind(slow_path);
+    (void) generate_normal_entry(false);
+
+    return entry;
+  }
+#endif // SERIALGC
+
+  // If G1 is not enabled then attempt to go through the accessor entry point
+  // Reference.get is an accessor
+  return generate_accessor_entry();
+}
+
+
 // Interpreter stub for calling a native method. (asm interpreter)
 // This sets up a somewhat different looking stack for calling the
 // native method than the typical interpreter frame setup.
@@ -1463,6 +1552,8 @@
   case Interpreter::java_lang_math_log     : // fall thru
   case Interpreter::java_lang_math_log10   : // fall thru
   case Interpreter::java_lang_math_sqrt    : entry_point = ((InterpreterGenerator*) this)->generate_math_entry(kind);    break;
+  case Interpreter::java_lang_ref_reference_get
+                                           : entry_point = ((InterpreterGenerator*)this)->generate_Reference_get_entry(); break;
   default                                  : ShouldNotReachHere();                                                       break;
   }
 
--- a/src/cpu/x86/vm/templateTable_x86_32.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/templateTable_x86_32.cpp	Wed May 04 16:38:05 2011 -0700
@@ -140,7 +140,12 @@
         }
         __ get_thread(rcx);
         __ save_bcp();
-        __ g1_write_barrier_pre(rdx, rcx, rsi, rbx, val != noreg);
+        __ g1_write_barrier_pre(rdx /* obj */,
+                                rbx /* pre_val */,
+                                rcx /* thread */,
+                                rsi /* tmp */,
+                                val != noreg /* tosca_live */,
+                                false /* expand_call */);
 
         // Do the actual store
         // noreg means NULL
@@ -149,7 +154,11 @@
           // No post barrier for NULL
         } else {
           __ movl(Address(rdx, 0), val);
-          __ g1_write_barrier_post(rdx, rax, rcx, rbx, rsi);
+          __ g1_write_barrier_post(rdx /* store_adr */,
+                                   val /* new_val */,
+                                   rcx /* thread */,
+                                   rbx /* tmp */,
+                                   rsi /* tmp2 */);
         }
         __ restore_bcp();
 
--- a/src/cpu/x86/vm/templateTable_x86_64.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/x86/vm/templateTable_x86_64.cpp	Wed May 04 16:38:05 2011 -0700
@@ -147,12 +147,21 @@
         } else {
           __ leaq(rdx, obj);
         }
-        __ g1_write_barrier_pre(rdx, r8, rbx, val != noreg);
+        __ g1_write_barrier_pre(rdx /* obj */,
+                                rbx /* pre_val */,
+                                r15_thread /* thread */,
+                                r8  /* tmp */,
+                                val != noreg /* tosca_live */,
+                                false /* expand_call */);
         if (val == noreg) {
           __ store_heap_oop_null(Address(rdx, 0));
         } else {
           __ store_heap_oop(Address(rdx, 0), val);
-          __ g1_write_barrier_post(rdx, val, r8, rbx);
+          __ g1_write_barrier_post(rdx /* store_adr */,
+                                   val /* new_val */,
+                                   r15_thread /* thread */,
+                                   r8 /* tmp */,
+                                   rbx /* tmp2 */);
         }
 
       }
--- a/src/cpu/zero/vm/cppInterpreter_zero.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/zero/vm/cppInterpreter_zero.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1302,6 +1302,26 @@
   return generate_entry((address) CppInterpreter::accessor_entry);
 }
 
+address InterpreterGenerator::generate_Reference_get_entry(void) {
+#ifndef SERIALGC
+  if (UseG1GC) {
+    // We need to generate have a routine that generates code to:
+    //   * load the value in the referent field
+    //   * passes that value to the pre-barrier.
+    //
+    // In the case of G1 this will record the value of the
+    // referent in an SATB buffer if marking is active.
+    // This will cause concurrent marking to mark the referent
+    // field as live.
+    Unimplemented();
+  }
+#endif // SERIALGC
+
+  // If G1 is not enabled then attempt to go through the accessor entry point
+  // Reference.get is an accessor
+  return generate_accessor_entry();
+}
+
 address InterpreterGenerator::generate_native_entry(bool synchronized) {
   assert(synchronized == false, "should be");
 
@@ -1357,6 +1377,10 @@
     entry_point = ((InterpreterGenerator*) this)->generate_math_entry(kind);
     break;
 
+  case Interpreter::java_lang_ref_reference_get:
+    entry_point = ((InterpreterGenerator*)this)->generate_Reference_get_entry();
+    break;
+
   default:
     ShouldNotReachHere();
   }
--- a/src/cpu/zero/vm/interpreterGenerator_zero.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/cpu/zero/vm/interpreterGenerator_zero.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2007 Red Hat, Inc.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -37,6 +37,7 @@
   address generate_math_entry(AbstractInterpreter::MethodKind kind);
   address generate_empty_entry();
   address generate_accessor_entry();
+  address generate_Reference_get_entry();
   address generate_method_handle_entry();
 
 #endif // CPU_ZERO_VM_INTERPRETERGENERATOR_ZERO_HPP
--- a/src/os/windows/vm/os_windows.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/os/windows/vm/os_windows.cpp	Wed May 04 16:38:05 2011 -0700
@@ -920,6 +920,8 @@
   HINSTANCE dbghelp;
   EXCEPTION_POINTERS ep;
   MINIDUMP_EXCEPTION_INFORMATION mei;
+  MINIDUMP_EXCEPTION_INFORMATION* pmei;
+
   HANDLE hProcess = GetCurrentProcess();
   DWORD processId = GetCurrentProcessId();
   HANDLE dumpFile;
@@ -970,17 +972,22 @@
     VMError::report_coredump_status("Failed to create file for dumping", false);
     return;
   }
-
-  ep.ContextRecord = (PCONTEXT) contextRecord;
-  ep.ExceptionRecord = (PEXCEPTION_RECORD) exceptionRecord;
-
-  mei.ThreadId = GetCurrentThreadId();
-  mei.ExceptionPointers = &ep;
+  if (exceptionRecord != NULL && contextRecord != NULL) {
+    ep.ContextRecord = (PCONTEXT) contextRecord;
+    ep.ExceptionRecord = (PEXCEPTION_RECORD) exceptionRecord;
+
+    mei.ThreadId = GetCurrentThreadId();
+    mei.ExceptionPointers = &ep;
+    pmei = &mei;
+  } else {
+    pmei = NULL;
+  }
+
 
   // Older versions of dbghelp.dll (the one shipped with Win2003 for example) may not support all
   // the dump types we really want. If first call fails, lets fall back to just use MiniDumpWithFullMemory then.
-  if (_MiniDumpWriteDump(hProcess, processId, dumpFile, dumpType, &mei, NULL, NULL) == false &&
-      _MiniDumpWriteDump(hProcess, processId, dumpFile, (MINIDUMP_TYPE)MiniDumpWithFullMemory, &mei, NULL, NULL) == false) {
+  if (_MiniDumpWriteDump(hProcess, processId, dumpFile, dumpType, pmei, NULL, NULL) == false &&
+      _MiniDumpWriteDump(hProcess, processId, dumpFile, (MINIDUMP_TYPE)MiniDumpWithFullMemory, pmei, NULL, NULL) == false) {
     VMError::report_coredump_status("Call to MiniDumpWriteDump() failed", false);
   } else {
     VMError::report_coredump_status(buffer, true);
--- a/src/share/vm/c1/c1_CodeStubs.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/c1/c1_CodeStubs.hpp	Wed May 04 16:38:05 2011 -0700
@@ -519,42 +519,126 @@
 // Code stubs for Garbage-First barriers.
 class G1PreBarrierStub: public CodeStub {
  private:
+  bool _do_load;
   LIR_Opr _addr;
   LIR_Opr _pre_val;
   LIR_PatchCode _patch_code;
   CodeEmitInfo* _info;
 
  public:
+  // Version that _does_ generate a load of the previous value from addr.
+  // addr (the address of the field to be read) must be a LIR_Address
   // pre_val (a temporary register) must be a register;
-  // addr (the address of the field to be read) must be a LIR_Address
   G1PreBarrierStub(LIR_Opr addr, LIR_Opr pre_val, LIR_PatchCode patch_code, CodeEmitInfo* info) :
-    _addr(addr), _pre_val(pre_val), _patch_code(patch_code), _info(info)
+    _addr(addr), _pre_val(pre_val), _do_load(true),
+    _patch_code(patch_code), _info(info)
   {
     assert(_pre_val->is_register(), "should be temporary register");
     assert(_addr->is_address(), "should be the address of the field");
   }
 
+  // Version that _does not_ generate load of the previous value; the
+  // previous value is assumed to have already been loaded into pre_val.
+  G1PreBarrierStub(LIR_Opr pre_val) :
+    _addr(LIR_OprFact::illegalOpr), _pre_val(pre_val), _do_load(false),
+    _patch_code(lir_patch_none), _info(NULL)
+  {
+    assert(_pre_val->is_register(), "should be a register");
+  }
+
   LIR_Opr addr() const { return _addr; }
   LIR_Opr pre_val() const { return _pre_val; }
   LIR_PatchCode patch_code() const { return _patch_code; }
   CodeEmitInfo* info() const { return _info; }
+  bool do_load() const { return _do_load; }
 
   virtual void emit_code(LIR_Assembler* e);
   virtual void visit(LIR_OpVisitState* visitor) {
-    // don't pass in the code emit info since it's processed in the fast
-    // path
-    if (_info != NULL)
-      visitor->do_slow_case(_info);
-    else
+    if (_do_load) {
+      // don't pass in the code emit info since it's processed in the fast
+      // path
+      if (_info != NULL)
+        visitor->do_slow_case(_info);
+      else
+        visitor->do_slow_case();
+
+      visitor->do_input(_addr);
+      visitor->do_temp(_pre_val);
+    } else {
       visitor->do_slow_case();
-    visitor->do_input(_addr);
-    visitor->do_temp(_pre_val);
+      visitor->do_input(_pre_val);
+    }
   }
 #ifndef PRODUCT
   virtual void print_name(outputStream* out) const { out->print("G1PreBarrierStub"); }
 #endif // PRODUCT
 };
 
+// This G1 barrier code stub is used in Unsafe.getObject.
+// It generates a sequence of guards around the SATB
+// barrier code that are used to detect when we have
+// the referent field of a Reference object.
+// The first check is assumed to have been generated
+// in the code generated for Unsafe.getObject().
+
+class G1UnsafeGetObjSATBBarrierStub: public CodeStub {
+ private:
+  LIR_Opr _val;
+  LIR_Opr _src;
+
+  LIR_Opr _tmp;
+  LIR_Opr _thread;
+
+  bool _gen_src_check;
+
+ public:
+  // A G1 barrier that is guarded by generated guards that determine whether
+  // val (which is the result of Unsafe.getObject() should be recorded in an
+  // SATB log buffer. We could be reading the referent field of a Reference object
+  // using Unsafe.getObject() and we need to record the referent.
+  //
+  // * val is the operand returned by the unsafe.getObject routine.
+  // * src is the base object
+  // * tmp is a temp used to load the klass of src, and then reference type
+  // * thread is the thread object.
+
+  G1UnsafeGetObjSATBBarrierStub(LIR_Opr val, LIR_Opr src,
+                                LIR_Opr tmp, LIR_Opr thread,
+                                bool gen_src_check) :
+    _val(val), _src(src),
+    _tmp(tmp), _thread(thread),
+    _gen_src_check(gen_src_check)
+  {
+    assert(_val->is_register(), "should have already been loaded");
+    assert(_src->is_register(), "should have already been loaded");
+
+    assert(_tmp->is_register(), "should be a temporary register");
+  }
+
+  LIR_Opr val() const { return _val; }
+  LIR_Opr src() const { return _src; }
+
+  LIR_Opr tmp() const { return _tmp; }
+  LIR_Opr thread() const { return _thread; }
+
+  bool gen_src_check() const { return _gen_src_check; }
+
+  virtual void emit_code(LIR_Assembler* e);
+
+  virtual void visit(LIR_OpVisitState* visitor) {
+    visitor->do_slow_case();
+    visitor->do_input(_val);
+    visitor->do_input(_src);
+    visitor->do_input(_thread);
+
+    visitor->do_temp(_tmp);
+  }
+
+#ifndef PRODUCT
+  virtual void print_name(outputStream* out) const { out->print("G1UnsafeGetObjSATBBarrierStub"); }
+#endif // PRODUCT
+};
+
 class G1PostBarrierStub: public CodeStub {
  private:
   LIR_Opr _addr;
--- a/src/share/vm/c1/c1_GraphBuilder.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/c1/c1_GraphBuilder.cpp	Wed May 04 16:38:05 2011 -0700
@@ -2913,6 +2913,46 @@
       block()->set_end(end);
       break;
     }
+
+  case vmIntrinsics::_Reference_get:
+    {
+      if (UseG1GC) {
+        // With java.lang.ref.reference.get() we must go through the
+        // intrinsic - when G1 is enabled - even when get() is the root
+        // method of the compile so that, if necessary, the value in
+        // the referent field of the reference object gets recorded by
+        // the pre-barrier code.
+        // Specifically, if G1 is enabled, the value in the referent
+        // field is recorded by the G1 SATB pre barrier. This will
+        // result in the referent being marked live and the reference
+        // object removed from the list of discovered references during
+        // reference processing.
+
+        // Set up a stream so that appending instructions works properly.
+        ciBytecodeStream s(scope->method());
+        s.reset_to_bci(0);
+        scope_data()->set_stream(&s);
+        s.next();
+
+        // setup the initial block state
+        _block = start_block;
+        _state = start_block->state()->copy_for_parsing();
+        _last  = start_block;
+        load_local(objectType, 0);
+
+        // Emit the intrinsic node.
+        bool result = try_inline_intrinsics(scope->method());
+        if (!result) BAILOUT("failed to inline intrinsic");
+        method_return(apop());
+
+        // connect the begin and end blocks and we're all done.
+        BlockEnd* end = last()->as_BlockEnd();
+        block()->set_end(end);
+        break;
+      }
+      // Otherwise, fall thru
+    }
+
   default:
     scope_data()->add_to_work_list(start_block);
     iterate_all_blocks();
@@ -3150,6 +3190,15 @@
       append_unsafe_CAS(callee);
       return true;
 
+    case vmIntrinsics::_Reference_get:
+      // It is only when G1 is enabled that we absolutely
+      // need to use the intrinsic version of Reference.get()
+      // so that the value in the referent field, if necessary,
+      // can be registered by the pre-barrier code.
+      if (!UseG1GC) return false;
+      preserves_state = true;
+      break;
+
     default                       : return false; // do not inline
   }
   // create intrinsic node
--- a/src/share/vm/c1/c1_Instruction.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/c1/c1_Instruction.cpp	Wed May 04 16:38:05 2011 -0700
@@ -596,7 +596,7 @@
 // of the inserted block, without recomputing the values of the other blocks
 // in the CFG. Therefore the value of "depth_first_number" in BlockBegin becomes meaningless.
 BlockBegin* BlockBegin::insert_block_between(BlockBegin* sux) {
-  BlockBegin* new_sux = new BlockBegin(-99);
+  BlockBegin* new_sux = new BlockBegin(end()->state()->bci());
 
   // mark this block (special treatment when block order is computed)
   new_sux->set(critical_edge_split_flag);
--- a/src/share/vm/c1/c1_LIRGenerator.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/c1/c1_LIRGenerator.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1209,6 +1209,38 @@
   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) {
@@ -1351,13 +1383,14 @@
 
 // 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:
@@ -1398,9 +1431,8 @@
 ////////////////////////////////////////////////////////////////////////
 #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) {
@@ -1419,26 +1451,40 @@
   // Read the marking-in-progress flag.
   LIR_Opr flag_val = new_register(T_INT);
   __ load(mark_active_flag_addr, flag_val);
-
-  LIR_PatchCode pre_val_patch_code =
-    patch ? lir_patch_normal : lir_patch_none;
-
-  LIR_Opr pre_val = new_register(T_OBJECT);
-
   __ 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));
+
+  LIR_PatchCode pre_val_patch_code = lir_patch_none;
+
+  CodeStub* slow;
+
+  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;
@@ -1662,6 +1708,8 @@
   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));
   }
@@ -2091,9 +2139,144 @@
   off.load_item();
   src.load_item();
 
-  LIR_Opr reg = reg = rlock_result(x, x->basic_type());
+  LIR_Opr reg = rlock_result(x, x->basic_type());
 
   get_Object_unsafe(reg, src.result(), off.result(), type, x->is_volatile());
+
+#ifndef SERIALGC
+  // We might be reading the value of the referent field of a
+  // Reference object in order to attach it back to the live
+  // object graph. If G1 is enabled then we need to record
+  // the value that is being returned in an SATB log buffer.
+  //
+  // We need to generate code similar to the following...
+  //
+  // if (offset == java_lang_ref_Reference::referent_offset) {
+  //   if (src != NULL) {
+  //     if (klass(src)->reference_type() != REF_NONE) {
+  //       pre_barrier(..., reg, ...);
+  //     }
+  //   }
+  // }
+  //
+  // The first non-constant check of either the offset or
+  // the src operand will be done here; the remainder
+  // will take place in the generated code stub.
+
+  if (UseG1GC && type == T_OBJECT) {
+    bool gen_code_stub = true;       // Assume we need to generate the slow code stub.
+    bool gen_offset_check = true;       // Assume the code stub has to generate the offset guard.
+    bool gen_source_check = true;       // Assume the code stub has to check the src object for null.
+
+    if (off.is_constant()) {
+      jlong off_con = (off.type()->is_int() ?
+                        (jlong) off.get_jint_constant() :
+                        off.get_jlong_constant());
+
+
+      if (off_con != (jlong) java_lang_ref_Reference::referent_offset) {
+        // The constant offset is something other than referent_offset.
+        // We can skip generating/checking the remaining guards and
+        // skip generation of the code stub.
+        gen_code_stub = false;
+      } else {
+        // The constant offset is the same as referent_offset -
+        // we do not need to generate a runtime offset check.
+        gen_offset_check = false;
+      }
+    }
+
+    // We don't need to generate stub if the source object is an array
+    if (gen_code_stub && src.type()->is_array()) {
+      gen_code_stub = false;
+    }
+
+    if (gen_code_stub) {
+      // We still need to continue with the checks.
+      if (src.is_constant()) {
+        ciObject* src_con = src.get_jobject_constant();
+
+        if (src_con->is_null_object()) {
+          // The constant src object is null - We can skip
+          // generating the code stub.
+          gen_code_stub = false;
+        } else {
+          // Non-null constant source object. We still have to generate
+          // the slow stub - but we don't need to generate the runtime
+          // null object check.
+          gen_source_check = false;
+        }
+      }
+    }
+
+    if (gen_code_stub) {
+      // Temoraries.
+      LIR_Opr src_klass = new_register(T_OBJECT);
+
+      // Get the thread pointer for the pre-barrier
+      LIR_Opr thread = getThreadPointer();
+
+      CodeStub* stub;
+
+      // We can have generate one runtime check here. Let's start with
+      // the offset check.
+      if (gen_offset_check) {
+        // if (offset == referent_offset) -> slow code stub
+        // If offset is an int then we can do the comparison with the
+        // referent_offset constant; otherwise we need to move
+        // referent_offset into a temporary register and generate
+        // a reg-reg compare.
+
+        LIR_Opr referent_off;
+
+        if (off.type()->is_int()) {
+          referent_off = LIR_OprFact::intConst(java_lang_ref_Reference::referent_offset);
+        } else {
+          assert(off.type()->is_long(), "what else?");
+          referent_off = new_register(T_LONG);
+          __ move(LIR_OprFact::longConst(java_lang_ref_Reference::referent_offset), referent_off);
+        }
+
+        __ cmp(lir_cond_equal, off.result(), referent_off);
+
+        // Optionally generate "src == null" check.
+        stub = new G1UnsafeGetObjSATBBarrierStub(reg, src.result(),
+                                                    src_klass, thread,
+                                                    gen_source_check);
+
+        __ branch(lir_cond_equal, as_BasicType(off.type()), stub);
+      } else {
+        if (gen_source_check) {
+          // offset is a const and equals referent offset
+          // if (source != null) -> slow code stub
+          __ cmp(lir_cond_notEqual, src.result(), LIR_OprFact::oopConst(NULL));
+
+          // Since we are generating the "if src == null" guard here,
+          // there is no need to generate the "src == null" check again.
+          stub = new G1UnsafeGetObjSATBBarrierStub(reg, src.result(),
+                                                    src_klass, thread,
+                                                    false);
+
+          __ branch(lir_cond_notEqual, T_OBJECT, stub);
+        } else {
+          // We have statically determined that offset == referent_offset
+          // && src != null so we unconditionally branch to code stub
+          // to perform the guards and record reg in the SATB log buffer.
+
+          stub = new G1UnsafeGetObjSATBBarrierStub(reg, src.result(),
+                                                    src_klass, thread,
+                                                    false);
+
+          __ branch(lir_cond_always, T_ILLEGAL, stub);
+        }
+      }
+
+      // Continuation point
+      __ branch_destination(stub->continuation());
+    }
+  }
+#endif // SERIALGC
+
   if (x->is_volatile() && os::is_MP()) __ membar_acquire();
 }
 
@@ -2759,6 +2942,10 @@
     do_AttemptUpdate(x);
     break;
 
+  case vmIntrinsics::_Reference_get:
+    do_Reference_get(x);
+    break;
+
   default: ShouldNotReachHere(); break;
   }
 }
--- a/src/share/vm/c1/c1_LIRGenerator.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/c1/c1_LIRGenerator.hpp	Wed May 04 16:38:05 2011 -0700
@@ -246,6 +246,7 @@
   void do_AttemptUpdate(Intrinsic* x);
   void do_NIOCheckIndex(Intrinsic* x);
   void do_FPIntrinsics(Intrinsic* x);
+  void do_Reference_get(Intrinsic* x);
 
   void do_UnsafePrefetch(UnsafePrefetch* x, bool is_store);
 
@@ -260,13 +261,14 @@
 
   // generic interface
 
-  void pre_barrier(LIR_Opr addr_opr, bool patch,  CodeEmitInfo* info);
+  void pre_barrier(LIR_Opr addr_opr, LIR_Opr pre_val, bool do_load, bool patch, CodeEmitInfo* info);
   void post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val);
 
   // specific implementations
   // pre barriers
 
-  void G1SATBCardTableModRef_pre_barrier(LIR_Opr addr_opr, bool patch,  CodeEmitInfo* info);
+  void G1SATBCardTableModRef_pre_barrier(LIR_Opr addr_opr, LIR_Opr pre_val,
+                                         bool do_load, bool patch, CodeEmitInfo* info);
 
   // post barriers
 
--- a/src/share/vm/classfile/classFileParser.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/classfile/classFileParser.cpp	Wed May 04 16:38:05 2011 -0700
@@ -2196,11 +2196,12 @@
                                               TRAPS) {
   typeArrayHandle nullHandle;
   int length = methods()->length();
-  // If JVMTI original method ordering is enabled we have to
+  // If JVMTI original method ordering or sharing is enabled we have to
   // remember the original class file ordering.
   // We temporarily use the vtable_index field in the methodOop to store the
   // class file index, so we can read in after calling qsort.
-  if (JvmtiExport::can_maintain_original_method_order()) {
+  // Put the method ordering in the shared archive.
+  if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) {
     for (int index = 0; index < length; index++) {
       methodOop m = methodOop(methods->obj_at(index));
       assert(!m->valid_vtable_index(), "vtable index should not be set");
@@ -2214,8 +2215,9 @@
                               methods_parameter_annotations(),
                               methods_default_annotations());
 
-  // If JVMTI original method ordering is enabled construct int array remembering the original ordering
-  if (JvmtiExport::can_maintain_original_method_order()) {
+  // If JVMTI original method ordering or sharing is enabled construct int
+  // array remembering the original ordering
+  if (JvmtiExport::can_maintain_original_method_order() || DumpSharedSpaces) {
     typeArrayOop new_ordering = oopFactory::new_permanent_intArray(length, CHECK_(nullHandle));
     typeArrayHandle method_ordering(THREAD, new_ordering);
     for (int index = 0; index < length; index++) {
--- a/src/share/vm/classfile/systemDictionary.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/classfile/systemDictionary.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1255,6 +1255,16 @@
         methodHandle m(THREAD, methodOop(methods->obj_at(index2)));
         m()->link_method(m, CHECK_(nh));
       }
+      if (JvmtiExport::has_redefined_a_class()) {
+        // Reinitialize vtable because RedefineClasses may have changed some
+        // entries in this vtable for super classes so the CDS vtable might
+        // point to old or obsolete entries.  RedefineClasses doesn't fix up
+        // vtables in the shared system dictionary, only the main one.
+        // It also redefines the itable too so fix that too.
+        ResourceMark rm(THREAD);
+        ik->vtable()->initialize_vtable(false, CHECK_(nh));
+        ik->itable()->initialize_itable(false, CHECK_(nh));
+      }
     }
 
     if (TraceClassLoading) {
--- a/src/share/vm/classfile/vmSymbols.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/classfile/vmSymbols.hpp	Wed May 04 16:38:05 2011 -0700
@@ -678,6 +678,10 @@
   do_intrinsic(_checkIndex,               java_nio_Buffer,        checkIndex_name, int_int_signature,            F_R)   \
    do_name(     checkIndex_name,                                 "checkIndex")                                          \
                                                                                                                         \
+  /* java/lang/ref/Reference */                                                                                         \
+  do_intrinsic(_Reference_get,            java_lang_ref_Reference, get_name,    void_object_signature, F_R)             \
+                                                                                                                        \
+                                                                                                                        \
   do_class(sun_misc_AtomicLongCSImpl,     "sun/misc/AtomicLongCSImpl")                                                  \
   do_intrinsic(_get_AtomicLong,           sun_misc_AtomicLongCSImpl, get_name, void_long_signature,              F_R)   \
   /*   (symbols get_name and void_long_signature defined above) */                                                      \
--- a/src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp	Wed May 04 16:38:05 2011 -0700
@@ -172,7 +172,7 @@
 
   // hash a given key (index of card_ptr) with the specified size
   static unsigned int hash(size_t key, size_t size) {
-    return (unsigned int) key % size;
+    return (unsigned int) (key % size);
   }
 
   // hash a given key (index of card_ptr)
@@ -180,11 +180,11 @@
     return hash(key, _n_card_counts);
   }
 
-  unsigned ptr_2_card_num(jbyte* card_ptr) {
-    return (unsigned) (card_ptr - _ct_bot);
+  unsigned int ptr_2_card_num(jbyte* card_ptr) {
+    return (unsigned int) (card_ptr - _ct_bot);
   }
 
-  jbyte* card_num_2_ptr(unsigned card_num) {
+  jbyte* card_num_2_ptr(unsigned int card_num) {
     return (jbyte*) (_ct_bot + card_num);
   }
 
--- a/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -47,7 +47,9 @@
 
 
 void G1SATBCardTableModRefBS::enqueue(oop pre_val) {
-  assert(pre_val->is_oop_or_null(true), "Error");
+  // Nulls should have been already filtered.
+  assert(pre_val->is_oop(true), "Error");
+
   if (!JavaThread::satb_mark_queue_set().is_active()) return;
   Thread* thr = Thread::current();
   if (thr->is_Java_thread()) {
@@ -59,20 +61,6 @@
   }
 }
 
-// When we know the current java thread:
-template <class T> void
-G1SATBCardTableModRefBS::write_ref_field_pre_static(T* field,
-                                                    oop new_val,
-                                                    JavaThread* jt) {
-  if (!JavaThread::satb_mark_queue_set().is_active()) return;
-  T heap_oop = oopDesc::load_heap_oop(field);
-  if (!oopDesc::is_null(heap_oop)) {
-    oop pre_val = oopDesc::decode_heap_oop_not_null(heap_oop);
-    assert(pre_val->is_oop(true /* ignore mark word */), "Error");
-    jt->satb_mark_queue().enqueue(pre_val);
-  }
-}
-
 template <class T> void
 G1SATBCardTableModRefBS::write_ref_array_pre_work(T* dst, int count) {
   if (!JavaThread::satb_mark_queue_set().is_active()) return;
--- a/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.hpp	Wed May 04 16:38:05 2011 -0700
@@ -37,12 +37,11 @@
 // snapshot-at-the-beginning marking.
 
 class G1SATBCardTableModRefBS: public CardTableModRefBSForCTRS {
-private:
+public:
   // Add "pre_val" to a set of objects that may have been disconnected from the
   // pre-marking object graph.
   static void enqueue(oop pre_val);
 
-public:
   G1SATBCardTableModRefBS(MemRegion whole_heap,
                           int max_covered_regions);
 
@@ -61,10 +60,6 @@
     }
   }
 
-  // When we know the current java thread:
-  template <class T> static void write_ref_field_pre_static(T* field, oop newVal,
-                                                            JavaThread* jt);
-
   // We export this to make it available in cases where the static
   // type of the barrier set is known.  Note that it is non-virtual.
   template <class T> inline void inline_write_ref_field_pre(T* field, oop newVal) {
--- a/src/share/vm/gc_implementation/g1/g1_globals.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/g1/g1_globals.hpp	Wed May 04 16:38:05 2011 -0700
@@ -89,13 +89,9 @@
           "The number of discovered reference objects to process before "   \
           "draining concurrent marking work queues.")                       \
                                                                             \
-  experimental(bool, G1UseConcMarkReferenceProcessing, false,               \
+  experimental(bool, G1UseConcMarkReferenceProcessing, true,                \
           "If true, enable reference discovery during concurrent "          \
-          "marking and reference processing at the end of remark "          \
-          "(unsafe).")                                                      \
-                                                                            \
-  develop(bool, G1SATBBarrierPrintNullPreVals, false,                       \
-          "If true, count frac of ptr writes with null pre-vals.")          \
+          "marking and reference processing at the end of remark.")         \
                                                                             \
   product(intx, G1SATBBufferSize, 1*K,                                      \
           "Number of entries in an SATB log buffer.")                       \
@@ -150,12 +146,6 @@
   develop(bool, G1PrintParCleanupStats, false,                              \
           "When true, print extra stats about parallel cleanup.")           \
                                                                             \
-  develop(bool, G1DisablePreBarrier, false,                                 \
-          "Disable generation of pre-barrier (i.e., marking barrier)   ")   \
-                                                                            \
-  develop(bool, G1DisablePostBarrier, false,                                \
-          "Disable generation of post-barrier (i.e., RS barrier)   ")       \
-                                                                            \
   product(intx, G1UpdateBufferSize, 256,                                    \
           "Size of an update buffer")                                       \
                                                                             \
--- a/src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parNew/parCardTableModRefBS.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2010 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2011 Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,7 +36,6 @@
 void CardTableModRefBS::par_non_clean_card_iterate_work(Space* sp, MemRegion mr,
                                                         DirtyCardToOopClosure* dcto_cl,
                                                         MemRegionClosure* cl,
-                                                        bool clear,
                                                         int n_threads) {
   if (n_threads > 0) {
     assert((n_threads == 1 && ParallelGCThreads == 0) ||
@@ -57,7 +56,7 @@
 
     int stride = 0;
     while (!pst->is_task_claimed(/* reference */ stride)) {
-      process_stride(sp, mr, stride, n_strides, dcto_cl, cl, clear,
+      process_stride(sp, mr, stride, n_strides, dcto_cl, cl,
                      lowest_non_clean,
                      lowest_non_clean_base_chunk_index,
                      lowest_non_clean_chunk_size);
@@ -83,7 +82,6 @@
                jint stride, int n_strides,
                DirtyCardToOopClosure* dcto_cl,
                MemRegionClosure* cl,
-               bool clear,
                jbyte** lowest_non_clean,
                uintptr_t lowest_non_clean_base_chunk_index,
                size_t    lowest_non_clean_chunk_size) {
@@ -129,7 +127,7 @@
                              lowest_non_clean_base_chunk_index,
                              lowest_non_clean_chunk_size);
 
-    non_clean_card_iterate_work(chunk_mr, cl, clear);
+    non_clean_card_iterate_work(chunk_mr, cl);
 
     // Find the next chunk of the stride.
     chunk_card_start += CardsPerStrideChunk * n_strides;
--- a/src/share/vm/gc_implementation/parallelScavenge/psOldGen.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psOldGen.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -176,10 +176,6 @@
   object_mark_sweep()->compact(ZapUnusedHeapArea);
 }
 
-void PSOldGen::move_and_update(ParCompactionManager* cm) {
-  PSParallelCompact::move_and_update(cm, PSParallelCompact::old_space_id);
-}
-
 size_t PSOldGen::contiguous_available() const {
   return object_space()->free_in_bytes() + virtual_space()->uncommitted_size();
 }
--- a/src/share/vm/gc_implementation/parallelScavenge/psOldGen.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psOldGen.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -143,9 +143,6 @@
   void adjust_pointers();
   void compact();
 
-  // Parallel old
-  virtual void move_and_update(ParCompactionManager* cm);
-
   // Size info
   size_t capacity_in_bytes() const        { return object_space()->capacity_in_bytes(); }
   size_t used_in_bytes() const            { return object_space()->used_in_bytes(); }
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Wed May 04 16:38:05 2011 -0700
@@ -2104,11 +2104,7 @@
     // klasses are used in the update of an object?
     compact_perm(vmthread_cm);
 
-    if (UseParallelOldGCCompacting) {
-      compact();
-    } else {
-      compact_serial(vmthread_cm);
-    }
+    compact();
 
     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
     // done before resizing.
@@ -2582,18 +2578,16 @@
     // each thread?
     if (total_dense_prefix_regions > 0) {
       uint tasks_for_dense_prefix = 1;
-      if (UseParallelDensePrefixUpdate) {
-        if (total_dense_prefix_regions <=
-            (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
-          // Don't over partition.  This assumes that
-          // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
-          // so there are not many regions to process.
-          tasks_for_dense_prefix = parallel_gc_threads;
-        } else {
-          // Over partition
-          tasks_for_dense_prefix = parallel_gc_threads *
-            PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
-        }
+      if (total_dense_prefix_regions <=
+          (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
+        // Don't over partition.  This assumes that
+        // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
+        // so there are not many regions to process.
+        tasks_for_dense_prefix = parallel_gc_threads;
+      } else {
+        // Over partition
+        tasks_for_dense_prefix = parallel_gc_threads *
+          PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
       }
       size_t regions_per_thread = total_dense_prefix_regions /
         tasks_for_dense_prefix;
@@ -2733,21 +2727,6 @@
 }
 #endif  // #ifdef ASSERT
 
-void PSParallelCompact::compact_serial(ParCompactionManager* cm) {
-  EventMark m("5 compact serial");
-  TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);
-
-  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
-  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
-
-  PSYoungGen* young_gen = heap->young_gen();
-  PSOldGen* old_gen = heap->old_gen();
-
-  old_gen->start_array()->reset();
-  old_gen->move_and_update(cm);
-  young_gen->move_and_update(cm);
-}
-
 void
 PSParallelCompact::follow_weak_klass_links() {
   // All klasses on the revisit stack are marked at this point.
@@ -3530,11 +3509,8 @@
            "Object liveness is wrong.");
     return ParMarkBitMap::incomplete;
   }
-  assert(UseParallelOldGCDensePrefix ||
-         (HeapMaximumCompactionInterval > 1) ||
-         (MarkSweepAlwaysCompactCount > 1) ||
-         (forwarding_ptr == new_pointer),
-    "Calculation of new location is incorrect");
+  assert(HeapMaximumCompactionInterval > 1 || MarkSweepAlwaysCompactCount > 1 ||
+         forwarding_ptr == new_pointer, "new location is incorrect");
   return ParMarkBitMap::incomplete;
 }
 
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1027,9 +1027,6 @@
                                        ParallelTaskTerminator* terminator_ptr,
                                        uint parallel_gc_threads);
 
-  // For debugging only - compacts the old gen serially
-  static void compact_serial(ParCompactionManager* cm);
-
   // If objects are left in eden after a collection, try to move the boundary
   // and absorb them into the old gen.  Returns true if eden was emptied.
   static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
--- a/src/share/vm/gc_implementation/parallelScavenge/psPermGen.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psPermGen.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -121,12 +121,6 @@
   }
 }
 
-
-
-void PSPermGen::move_and_update(ParCompactionManager* cm) {
-  PSParallelCompact::move_and_update(cm, PSParallelCompact::perm_space_id);
-}
-
 void PSPermGen::precompact() {
   // Reset start array first.
   _start_array.reset();
--- a/src/share/vm/gc_implementation/parallelScavenge/psPermGen.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psPermGen.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -51,9 +51,6 @@
   // MarkSweep code
   virtual void precompact();
 
-  // Parallel old
-  virtual void move_and_update(ParCompactionManager* cm);
-
   virtual const char* name() const { return "PSPermGen"; }
 };
 
--- a/src/share/vm/gc_implementation/parallelScavenge/psYoungGen.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psYoungGen.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -792,12 +792,6 @@
   to_mark_sweep()->compact(false);
 }
 
-void PSYoungGen::move_and_update(ParCompactionManager* cm) {
-  PSParallelCompact::move_and_update(cm, PSParallelCompact::eden_space_id);
-  PSParallelCompact::move_and_update(cm, PSParallelCompact::from_space_id);
-  PSParallelCompact::move_and_update(cm, PSParallelCompact::to_space_id);
-}
-
 void PSYoungGen::print() const { print_on(tty); }
 void PSYoungGen::print_on(outputStream* st) const {
   st->print(" %-15s", "PSYoungGen");
--- a/src/share/vm/gc_implementation/parallelScavenge/psYoungGen.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/parallelScavenge/psYoungGen.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -127,9 +127,6 @@
   void adjust_pointers();
   void compact();
 
-  // Parallel Old
-  void move_and_update(ParCompactionManager* cm);
-
   // Called during/after gc
   void swap_spaces();
 
--- a/src/share/vm/gc_implementation/shared/allocationStats.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/gc_implementation/shared/allocationStats.hpp	Wed May 04 16:38:05 2011 -0700
@@ -76,7 +76,7 @@
     _beforeSweep = 0;
     _coalBirths = 0;
     _coalDeaths = 0;
-    _splitBirths = split_birth? 1 : 0;
+    _splitBirths = (split_birth ? 1 : 0);
     _splitDeaths = 0;
     _returnedBytes = 0;
   }
--- a/src/share/vm/interpreter/abstractInterpreter.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/interpreter/abstractInterpreter.hpp	Wed May 04 16:38:05 2011 -0700
@@ -104,6 +104,7 @@
     java_lang_math_sqrt,                                        // implementation of java.lang.Math.sqrt  (x)
     java_lang_math_log,                                         // implementation of java.lang.Math.log   (x)
     java_lang_math_log10,                                       // implementation of java.lang.Math.log10 (x)
+    java_lang_ref_reference_get,                                // implementation of java.lang.ref.Reference.get()
     number_of_method_entries,
     invalid = -1
   };
@@ -140,7 +141,7 @@
   // Method activation
   static MethodKind method_kind(methodHandle m);
   static address    entry_for_kind(MethodKind k)                { assert(0 <= k && k < number_of_method_entries, "illegal kind"); return _entry_table[k]; }
-  static address    entry_for_method(methodHandle m)            { return _entry_table[method_kind(m)]; }
+  static address    entry_for_method(methodHandle m)            { return entry_for_kind(method_kind(m)); }
 
   static void       print_method_kind(MethodKind kind)          PRODUCT_RETURN;
 
--- a/src/share/vm/interpreter/cppInterpreter.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/interpreter/cppInterpreter.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -125,6 +125,7 @@
     method_entry(java_lang_math_sqrt  );
     method_entry(java_lang_math_log   );
     method_entry(java_lang_math_log10 );
+    method_entry(java_lang_ref_reference_get);
     Interpreter::_native_entry_begin = Interpreter::code()->code_end();
     method_entry(native);
     method_entry(native_synchronized);
--- a/src/share/vm/interpreter/interpreter.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/interpreter/interpreter.cpp	Wed May 04 16:38:05 2011 -0700
@@ -208,12 +208,6 @@
     return empty;
   }
 
-  // Accessor method?
-  if (m->is_accessor()) {
-    assert(m->size_of_parameters() == 1, "fast code for accessors assumes parameter size = 1");
-    return accessor;
-  }
-
   // Special intrinsic method?
   // Note: This test must come _after_ the test for native methods,
   //       otherwise we will run into problems with JDK 1.2, see also
@@ -227,6 +221,15 @@
     case vmIntrinsics::_dsqrt : return java_lang_math_sqrt ;
     case vmIntrinsics::_dlog  : return java_lang_math_log  ;
     case vmIntrinsics::_dlog10: return java_lang_math_log10;
+
+    case vmIntrinsics::_Reference_get:
+                                return java_lang_ref_reference_get;
+  }
+
+  // Accessor method?
+  if (m->is_accessor()) {
+    assert(m->size_of_parameters() == 1, "fast code for accessors assumes parameter size = 1");
+    return accessor;
   }
 
   // Note: for now: zero locals for all non-empty methods
--- a/src/share/vm/interpreter/templateInterpreter.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/interpreter/templateInterpreter.cpp	Wed May 04 16:38:05 2011 -0700
@@ -372,6 +372,7 @@
   method_entry(java_lang_math_sqrt )
   method_entry(java_lang_math_log  )
   method_entry(java_lang_math_log10)
+  method_entry(java_lang_ref_reference_get)
 
   // all native method kinds (must be one contiguous block)
   Interpreter::_native_entry_begin = Interpreter::code()->code_end();
--- a/src/share/vm/memory/cardTableModRefBS.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/memory/cardTableModRefBS.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -459,18 +459,17 @@
 void CardTableModRefBS::non_clean_card_iterate(Space* sp,
                                                MemRegion mr,
                                                DirtyCardToOopClosure* dcto_cl,
-                                               MemRegionClosure* cl,
-                                               bool clear) {
+                                               MemRegionClosure* cl) {
   if (!mr.is_empty()) {
     int n_threads = SharedHeap::heap()->n_par_threads();
     if (n_threads > 0) {
 #ifndef SERIALGC
-      par_non_clean_card_iterate_work(sp, mr, dcto_cl, cl, clear, n_threads);
+      par_non_clean_card_iterate_work(sp, mr, dcto_cl, cl, n_threads);
 #else  // SERIALGC
       fatal("Parallel gc not supported here.");
 #endif // SERIALGC
     } else {
-      non_clean_card_iterate_work(mr, cl, clear);
+      non_clean_card_iterate_work(mr, cl);
     }
   }
 }
@@ -481,10 +480,7 @@
 // cards (and miss those marked precleaned). In that sense,
 // the name precleaned is currently somewhat of a misnomer.
 void CardTableModRefBS::non_clean_card_iterate_work(MemRegion mr,
-                                                    MemRegionClosure* cl,
-                                                    bool clear) {
-  // Figure out whether we have to worry about parallelism.
-  bool is_par = (SharedHeap::heap()->n_par_threads() > 1);
+                                                    MemRegionClosure* cl) {
   for (int i = 0; i < _cur_covered_regions; i++) {
     MemRegion mri = mr.intersection(_covered[i]);
     if (mri.word_size() > 0) {
@@ -506,22 +502,6 @@
           MemRegion cur_cards(addr_for(cur_entry),
                               non_clean_cards * card_size_in_words);
           MemRegion dirty_region = cur_cards.intersection(mri);
-          if (clear) {
-            for (size_t i = 0; i < non_clean_cards; i++) {
-              // Clean the dirty cards (but leave the other non-clean
-              // alone.)  If parallel, do the cleaning atomically.
-              jbyte cur_entry_val = cur_entry[i];
-              if (card_is_dirty_wrt_gen_iter(cur_entry_val)) {
-                if (is_par) {
-                  jbyte res = Atomic::cmpxchg(clean_card, &cur_entry[i], cur_entry_val);
-                  assert(res != clean_card,
-                         "Dirty card mysteriously cleaned");
-                } else {
-                  cur_entry[i] = clean_card;
-                }
-              }
-            }
-          }
           cl->do_MemRegion(dirty_region);
         }
         cur_entry = next_entry;
@@ -530,22 +510,6 @@
   }
 }
 
-void CardTableModRefBS::mod_oop_in_space_iterate(Space* sp,
-                                                 OopClosure* cl,
-                                                 bool clear,
-                                                 bool before_save_marks) {
-  // Note that dcto_cl is resource-allocated, so there is no
-  // corresponding "delete".
-  DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision());
-  MemRegion used_mr;
-  if (before_save_marks) {
-    used_mr = sp->used_region_at_save_marks();
-  } else {
-    used_mr = sp->used_region();
-  }
-  non_clean_card_iterate(sp, used_mr, dcto_cl, dcto_cl, clear);
-}
-
 void CardTableModRefBS::dirty_MemRegion(MemRegion mr) {
   assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
   assert((HeapWord*)align_size_up  ((uintptr_t)mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );
@@ -593,9 +557,8 @@
   memset(first, dirty_card, last-first);
 }
 
-// NOTES:
-// (1) Unlike mod_oop_in_space_iterate() above, dirty_card_iterate()
-//     iterates over dirty cards ranges in increasing address order.
+// Unlike several other card table methods, dirty_card_iterate()
+// iterates over dirty cards ranges in increasing address order.
 void CardTableModRefBS::dirty_card_iterate(MemRegion mr,
                                            MemRegionClosure* cl) {
   for (int i = 0; i < _cur_covered_regions; i++) {
@@ -698,7 +661,7 @@
 
 void CardTableModRefBS::verify_clean_region(MemRegion mr) {
   GuaranteeNotModClosure blk(this);
-  non_clean_card_iterate_work(mr, &blk, false);
+  non_clean_card_iterate_work(mr, &blk);
 }
 
 // To verify a MemRegion is entirely dirty this closure is passed to
--- a/src/share/vm/memory/cardTableModRefBS.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/memory/cardTableModRefBS.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -171,17 +171,14 @@
   // mode if worker threads are available.
   void non_clean_card_iterate(Space* sp, MemRegion mr,
                               DirtyCardToOopClosure* dcto_cl,
-                              MemRegionClosure* cl,
-                              bool clear);
+                              MemRegionClosure* cl);
 
   // Utility function used to implement the other versions below.
-  void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl,
-                                   bool clear);
+  void non_clean_card_iterate_work(MemRegion mr, MemRegionClosure* cl);
 
   void par_non_clean_card_iterate_work(Space* sp, MemRegion mr,
                                        DirtyCardToOopClosure* dcto_cl,
                                        MemRegionClosure* cl,
-                                       bool clear,
                                        int n_threads);
 
   // Dirty the bytes corresponding to "mr" (not all of which must be
@@ -241,7 +238,6 @@
                       jint stride, int n_strides,
                       DirtyCardToOopClosure* dcto_cl,
                       MemRegionClosure* cl,
-                      bool clear,
                       jbyte** lowest_non_clean,
                       uintptr_t lowest_non_clean_base_chunk_index,
                       size_t lowest_non_clean_chunk_size);
@@ -402,9 +398,6 @@
   virtual void invalidate(MemRegion mr, bool whole_heap = false);
   void clear(MemRegion mr);
   void dirty(MemRegion mr);
-  void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
-                                bool clear = false,
-                                bool before_save_marks = false);
 
   // *** Card-table-RemSet-specific things.
 
@@ -415,18 +408,15 @@
   // *decreasing* address order.  (This order aids with imprecise card
   // marking, where a dirty card may cause scanning, and summarization
   // marking, of objects that extend onto subsequent cards.)
-  // If "clear" is true, the card is (conceptually) marked unmodified before
-  // applying the closure.
-  void mod_card_iterate(MemRegionClosure* cl, bool clear = false) {
-    non_clean_card_iterate_work(_whole_heap, cl, clear);
+  void mod_card_iterate(MemRegionClosure* cl) {
+    non_clean_card_iterate_work(_whole_heap, cl);
   }
 
   // Like the "mod_cards_iterate" above, except only invokes the closure
   // for cards within the MemRegion "mr" (which is required to be
   // card-aligned and sized.)
-  void mod_card_iterate(MemRegion mr, MemRegionClosure* cl,
-                        bool clear = false) {
-    non_clean_card_iterate_work(mr, cl, clear);
+  void mod_card_iterate(MemRegion mr, MemRegionClosure* cl) {
+    non_clean_card_iterate_work(mr, cl);
   }
 
   static uintx ct_max_alignment_constraint();
--- a/src/share/vm/memory/cardTableRS.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/memory/cardTableRS.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -247,7 +247,7 @@
   ClearNoncleanCardWrapper clear_cl(dcto_cl, this);
 
   _ct_bs->non_clean_card_iterate(sp, sp->used_region_at_save_marks(),
-                                dcto_cl, &clear_cl, false);
+                                dcto_cl, &clear_cl);
 }
 
 void CardTableRS::clear_into_younger(Generation* gen, bool clear_perm) {
--- a/src/share/vm/memory/dump.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/memory/dump.cpp	Wed May 04 16:38:05 2011 -0700
@@ -623,24 +623,48 @@
   }
 };
 
-// Itable indices are calculated based on methods array order
-// (see klassItable::compute_itable_index()).  Must reinitialize
+// Vtable and Itable indices are calculated based on methods array
+// order (see klassItable::compute_itable_index()).  Must reinitialize
 // after ALL methods of ALL classes have been reordered.
 // We assume that since checkconstraints is false, this method
 // cannot throw an exception.  An exception here would be
 // problematic since this is the VMThread, not a JavaThread.
 
-class ReinitializeItables: public ObjectClosure {
+class ReinitializeTables: public ObjectClosure {
 private:
   Thread* _thread;
 
 public:
-  ReinitializeItables(Thread* thread) : _thread(thread) {}
+  ReinitializeTables(Thread* thread) : _thread(thread) {}
+
+  // Initialize super vtable first, check if already initialized to avoid
+  // quadradic behavior.  The vtable is cleared in remove_unshareable_info.
+  void reinitialize_vtables(klassOop k) {
+    if (k->blueprint()->oop_is_instanceKlass()) {
+      instanceKlass* ik = instanceKlass::cast(k);
+      if (ik->vtable()->is_initialized()) return;
+      if (ik->super() != NULL) {
+        reinitialize_vtables(ik->super());
+      }
+      ik->vtable()->initialize_vtable(false, _thread);
+    }
+  }
 
   void do_object(oop obj) {
     if (obj->blueprint()->oop_is_instanceKlass()) {
       instanceKlass* ik = instanceKlass::cast((klassOop)obj);
+      ResourceMark rm(_thread);
       ik->itable()->initialize_itable(false, _thread);
+      reinitialize_vtables((klassOop)obj);
+#ifdef ASSERT
+      ik->vtable()->verify(tty, true);
+#endif // ASSERT
+    } else if (obj->blueprint()->oop_is_arrayKlass()) {
+      // The vtable for array klasses are that of its super class,
+      // ie. java.lang.Object.
+      arrayKlass* ak = arrayKlass::cast((klassOop)obj);
+      if (ak->vtable()->is_initialized()) return;
+      ak->vtable()->initialize_vtable(false, _thread);
     }
   }
 };
@@ -1205,9 +1229,9 @@
     gen->ro_space()->object_iterate(&sort);
     gen->rw_space()->object_iterate(&sort);
 
-    ReinitializeItables reinit_itables(THREAD);
-    gen->ro_space()->object_iterate(&reinit_itables);
-    gen->rw_space()->object_iterate(&reinit_itables);
+    ReinitializeTables reinit_tables(THREAD);
+    gen->ro_space()->object_iterate(&reinit_tables);
+    gen->rw_space()->object_iterate(&reinit_tables);
     tty->print_cr("done. ");
     tty->cr();
 
--- a/src/share/vm/memory/modRefBarrierSet.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/memory/modRefBarrierSet.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -88,15 +88,6 @@
     assert(false, "can't call");
   }
 
-  // Invoke "cl->do_oop" on (the address of) every possibly-modifed
-  // reference field in objects in "sp".  If "clear" is "true", the oops
-  // are no longer considered possibly modified after application of the
-  // closure.  If' "before_save_marks" is true, oops in objects allocated
-  // after the last call to "save_marks" on "sp" will not be considered.
-  virtual void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
-                                        bool clear = false,
-                                        bool before_save_marks = false) = 0;
-
   // Causes all refs in "mr" to be assumed to be modified.  If "whole_heap"
   // is true, the caller asserts that the entire heap is being invalidated,
   // which may admit an optimized implementation for some barriers.
--- a/src/share/vm/oops/instanceKlass.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/oops/instanceKlass.hpp	Wed May 04 16:38:05 2011 -0700
@@ -401,6 +401,8 @@
   ReferenceType reference_type() const     { return _reference_type; }
   void set_reference_type(ReferenceType t) { _reference_type = t; }
 
+  static int reference_type_offset_in_bytes() { return offset_of(instanceKlass, _reference_type); }
+
   // find local field, returns true if found
   bool find_local_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const;
   // find field in direct superinterfaces, returns the interface in which the field is defined
--- a/src/share/vm/oops/instanceKlassKlass.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/oops/instanceKlassKlass.cpp	Wed May 04 16:38:05 2011 -0700
@@ -690,7 +690,8 @@
     guarantee(method_ordering->is_perm(),              "should be in permspace");
     guarantee(method_ordering->is_typeArray(),         "should be type array");
     int length = method_ordering->length();
-    if (JvmtiExport::can_maintain_original_method_order()) {
+    if (JvmtiExport::can_maintain_original_method_order() ||
+        (UseSharedSpaces && length != 0)) {
       guarantee(length == methods->length(),           "invalid method ordering length");
       jlong sum = 0;
       for (j = 0; j < length; j++) {
--- a/src/share/vm/oops/klass.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/oops/klass.cpp	Wed May 04 16:38:05 2011 -0700
@@ -453,6 +453,14 @@
       ik->unlink_class();
     }
   }
+  // Clear the Java vtable if the oop has one.
+  // The vtable isn't shareable because it's in the wrong order wrt the methods
+  // once the method names get moved and resorted.
+  klassVtable* vt = vtable();
+  if (vt != NULL) {
+    assert(oop_is_instance() || oop_is_array(), "nothing else has vtable");
+    vt->clear_vtable();
+  }
   set_subklass(NULL);
   set_next_sibling(NULL);
 }
--- a/src/share/vm/oops/klassVtable.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/oops/klassVtable.cpp	Wed May 04 16:38:05 2011 -0700
@@ -645,6 +645,15 @@
   }
 }
 
+// CDS/RedefineClasses support - clear vtables so they can be reinitialized
+void klassVtable::clear_vtable() {
+  for (int i = 0; i < _length; i++) table()[i].clear();
+}
+
+bool klassVtable::is_initialized() {
+  return _length == 0 || table()[0].method() != NULL;
+}
+
 
 // Garbage collection
 void klassVtable::oop_follow_contents() {
--- a/src/share/vm/oops/klassVtable.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/oops/klassVtable.hpp	Wed May 04 16:38:05 2011 -0700
@@ -75,7 +75,15 @@
 
   void initialize_vtable(bool checkconstraints, TRAPS);   // initialize vtable of a new klass
 
-  // conputes vtable length (in words) and the number of miranda methods
+  // CDS/RedefineClasses support - clear vtables so they can be reinitialized
+  // at dump time.  Clearing gives us an easy way to tell if the vtable has
+  // already been reinitialized at dump time (see dump.cpp).  Vtables can
+  // be initialized at run time by RedefineClasses so dumping the right order
+  // is necessary.
+  void clear_vtable();
+  bool is_initialized();
+
+  // computes vtable length (in words) and the number of miranda methods
   static void compute_vtable_size_and_num_mirandas(int &vtable_length, int &num_miranda_methods,
                                                    klassOop super, objArrayOop methods,
                                                    AccessFlags class_flags, Handle classloader,
--- a/src/share/vm/opto/compile.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/opto/compile.cpp	Wed May 04 16:38:05 2011 -0700
@@ -629,7 +629,7 @@
     initial_gvn()->transform_no_reclaim(top());
 
     // Set up tf(), start(), and find a CallGenerator.
-    CallGenerator* cg;
+    CallGenerator* cg = NULL;
     if (is_osr_compilation()) {
       const TypeTuple *domain = StartOSRNode::osr_domain();
       const TypeTuple *range = TypeTuple::make_range(method()->signature());
@@ -644,9 +644,24 @@
       StartNode* s = new (this, 2) StartNode(root(), tf()->domain());
       initial_gvn()->set_type_bottom(s);
       init_start(s);
-      float past_uses = method()->interpreter_invocation_count();
-      float expected_uses = past_uses;
-      cg = CallGenerator::for_inline(method(), expected_uses);
+      if (method()->intrinsic_id() == vmIntrinsics::_Reference_get && UseG1GC) {
+        // With java.lang.ref.reference.get() we must go through the
+        // intrinsic when G1 is enabled - even when get() is the root
+        // method of the compile - so that, if necessary, the value in
+        // the referent field of the reference object gets recorded by
+        // the pre-barrier code.
+        // Specifically, if G1 is enabled, the value in the referent
+        // field is recorded by the G1 SATB pre barrier. This will
+        // result in the referent being marked live and the reference
+        // object removed from the list of discovered references during
+        // reference processing.
+        cg = find_intrinsic(method(), false);
+      }
+      if (cg == NULL) {
+        float past_uses = method()->interpreter_invocation_count();
+        float expected_uses = past_uses;
+        cg = CallGenerator::for_inline(method(), expected_uses);
+      }
     }
     if (failing())  return;
     if (cg == NULL) {
@@ -2041,6 +2056,52 @@
   // Note that OffsetBot and OffsetTop are very negative.
 }
 
+// Eliminate trivially redundant StoreCMs and accumulate their
+// precedence edges.
+static void eliminate_redundant_card_marks(Node* n) {
+  assert(n->Opcode() == Op_StoreCM, "expected StoreCM");
+  if (n->in(MemNode::Address)->outcnt() > 1) {
+    // There are multiple users of the same address so it might be
+    // possible to eliminate some of the StoreCMs
+    Node* mem = n->in(MemNode::Memory);
+    Node* adr = n->in(MemNode::Address);
+    Node* val = n->in(MemNode::ValueIn);
+    Node* prev = n;
+    bool done = false;
+    // Walk the chain of StoreCMs eliminating ones that match.  As
+    // long as it's a chain of single users then the optimization is
+    // safe.  Eliminating partially redundant StoreCMs would require
+    // cloning copies down the other paths.
+    while (mem->Opcode() == Op_StoreCM && mem->outcnt() == 1 && !done) {
+      if (adr == mem->in(MemNode::Address) &&
+          val == mem->in(MemNode::ValueIn)) {
+        // redundant StoreCM
+        if (mem->req() > MemNode::OopStore) {
+          // Hasn't been processed by this code yet.
+          n->add_prec(mem->in(MemNode::OopStore));
+        } else {
+          // Already converted to precedence edge
+          for (uint i = mem->req(); i < mem->len(); i++) {
+            // Accumulate any precedence edges
+            if (mem->in(i) != NULL) {
+              n->add_prec(mem->in(i));
+            }
+          }
+          // Everything above this point has been processed.
+          done = true;
+        }
+        // Eliminate the previous StoreCM
+        prev->set_req(MemNode::Memory, mem->in(MemNode::Memory));
+        assert(mem->outcnt() == 0, "should be dead");
+        mem->disconnect_inputs(NULL);
+      } else {
+        prev = mem;
+      }
+      mem = prev->in(MemNode::Memory);
+    }
+  }
+}
+
 //------------------------------final_graph_reshaping_impl----------------------
 // Implement items 1-5 from final_graph_reshaping below.
 static void final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc ) {
@@ -2167,9 +2228,19 @@
     frc.inc_float_count();
     goto handle_mem;
 
+  case Op_StoreCM:
+    {
+      // Convert OopStore dependence into precedence edge
+      Node* prec = n->in(MemNode::OopStore);
+      n->del_req(MemNode::OopStore);
+      n->add_prec(prec);
+      eliminate_redundant_card_marks(n);
+    }
+
+    // fall through
+
   case Op_StoreB:
   case Op_StoreC:
-  case Op_StoreCM:
   case Op_StorePConditional:
   case Op_StoreI:
   case Op_StoreL:
--- a/src/share/vm/opto/graphKit.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/opto/graphKit.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1457,19 +1457,22 @@
 }
 
 
-void GraphKit::pre_barrier(Node* ctl,
+void GraphKit::pre_barrier(bool do_load,
+                           Node* ctl,
                            Node* obj,
                            Node* adr,
                            uint  adr_idx,
                            Node* val,
                            const TypeOopPtr* val_type,
+                           Node* pre_val,
                            BasicType bt) {
+
   BarrierSet* bs = Universe::heap()->barrier_set();
   set_control(ctl);
   switch (bs->kind()) {
     case BarrierSet::G1SATBCT:
     case BarrierSet::G1SATBCTLogging:
-      g1_write_barrier_pre(obj, adr, adr_idx, val, val_type, bt);
+      g1_write_barrier_pre(do_load, obj, adr, adr_idx, val, val_type, pre_val, bt);
       break;
 
     case BarrierSet::CardTableModRef:
@@ -1532,7 +1535,11 @@
   uint adr_idx = C->get_alias_index(adr_type);
   assert(adr_idx != Compile::AliasIdxTop, "use other store_to_memory factory" );
 
-  pre_barrier(control(), obj, adr, adr_idx, val, val_type, bt);
+  pre_barrier(true /* do_load */,
+              control(), obj, adr, adr_idx, val, val_type,
+              NULL /* pre_val */,
+              bt);
+
   Node* store = store_to_memory(control(), adr, val, bt, adr_idx);
   post_barrier(control(), store, obj, adr, adr_idx, val, bt, use_precise);
   return store;
@@ -3470,12 +3477,31 @@
 }
 
 // G1 pre/post barriers
-void GraphKit::g1_write_barrier_pre(Node* obj,
+void GraphKit::g1_write_barrier_pre(bool do_load,
+                                    Node* obj,
                                     Node* adr,
                                     uint alias_idx,
                                     Node* val,
                                     const TypeOopPtr* val_type,
+                                    Node* pre_val,
                                     BasicType bt) {
+
+  // Some sanity checks
+  // Note: val is unused in this routine.
+
+  if (do_load) {
+    // We need to generate the load of the previous value
+    assert(obj != NULL, "must have a base");
+    assert(adr != NULL, "where are loading from?");
+    assert(pre_val == NULL, "loaded already?");
+    assert(val_type != NULL, "need a type");
+  } else {
+    // In this case both val_type and alias_idx are unused.
+    assert(pre_val != NULL, "must be loaded already");
+    assert(pre_val->bottom_type()->basic_type() == T_OBJECT, "or we shouldn't be here");
+  }
+  assert(bt == T_OBJECT, "or we shouldn't be here");
+
   IdealKit ideal(this, true);
 
   Node* tls = __ thread(); // ThreadLocalStorage
@@ -3497,32 +3523,28 @@
                                           PtrQueue::byte_offset_of_index());
   const int buffer_offset  = in_bytes(JavaThread::satb_mark_queue_offset() +  // 652
                                           PtrQueue::byte_offset_of_buf());
+
   // Now the actual pointers into the thread
-
-  // set_control( ctl);
-
   Node* marking_adr = __ AddP(no_base, tls, __ ConX(marking_offset));
   Node* buffer_adr  = __ AddP(no_base, tls, __ ConX(buffer_offset));
   Node* index_adr   = __ AddP(no_base, tls, __ ConX(index_offset));
 
   // Now some of the values
-
   Node* marking = __ load(__ ctrl(), marking_adr, TypeInt::INT, active_type, Compile::AliasIdxRaw);
 
   // if (!marking)
   __ if_then(marking, BoolTest::ne, zero); {
     Node* index   = __ load(__ ctrl(), index_adr, TypeInt::INT, T_INT, Compile::AliasIdxRaw);
 
-    const Type* t1 = adr->bottom_type();
-    const Type* t2 = val->bottom_type();
-
-    Node* orig = __ load(no_ctrl, adr, val_type, bt, alias_idx);
-    // if (orig != NULL)
-    __ if_then(orig, BoolTest::ne, null()); {
-      Node* buffer  = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw);
-
+    if (do_load) {
       // load original value
       // alias_idx correct??
+      pre_val = __ load(no_ctrl, adr, val_type, bt, alias_idx);
+    }
+
+    // if (pre_val != NULL)
+    __ if_then(pre_val, BoolTest::ne, null()); {
+      Node* buffer  = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw);
 
       // is the queue for this thread full?
       __ if_then(index, BoolTest::ne, zero, likely); {
@@ -3536,10 +3558,9 @@
         next_indexX = _gvn.transform( new (C, 2) ConvI2LNode(next_index, TypeLong::make(0, max_jlong, Type::WidenMax)) );
 #endif
 
-        // Now get the buffer location we will log the original value into and store it
+        // Now get the buffer location we will log the previous value into and store it
         Node *log_addr = __ AddP(no_base, buffer, next_indexX);
-        __ store(__ ctrl(), log_addr, orig, T_OBJECT, Compile::AliasIdxRaw);
-
+        __ store(__ ctrl(), log_addr, pre_val, T_OBJECT, Compile::AliasIdxRaw);
         // update the index
         __ store(__ ctrl(), index_adr, next_index, T_INT, Compile::AliasIdxRaw);
 
@@ -3547,9 +3568,9 @@
 
         // logging buffer is full, call the runtime
         const TypeFunc *tf = OptoRuntime::g1_wb_pre_Type();
-        __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_pre), "g1_wb_pre", orig, tls);
+        __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, SharedRuntime::g1_wb_pre), "g1_wb_pre", pre_val, tls);
       } __ end_if();  // (!index)
-    } __ end_if();  // (orig != NULL)
+    } __ end_if();  // (pre_val != NULL)
   } __ end_if();  // (!marking)
 
   // Final sync IdealKit and GraphKit.
--- a/src/share/vm/opto/graphKit.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/opto/graphKit.hpp	Wed May 04 16:38:05 2011 -0700
@@ -544,8 +544,10 @@
                              BasicType bt);
 
   // For the few case where the barriers need special help
-  void pre_barrier(Node* ctl, Node* obj, Node* adr, uint adr_idx,
-                   Node* val, const TypeOopPtr* val_type, BasicType bt);
+  void pre_barrier(bool do_load, Node* ctl,
+                   Node* obj, Node* adr, uint adr_idx, Node* val, const TypeOopPtr* val_type,
+                   Node* pre_val,
+                   BasicType bt);
 
   void post_barrier(Node* ctl, Node* store, Node* obj, Node* adr, uint adr_idx,
                     Node* val, BasicType bt, bool use_precise);
@@ -671,11 +673,13 @@
                           Node* adr,  uint adr_idx, Node* val, bool use_precise);
 
   // G1 pre/post barriers
-  void g1_write_barrier_pre(Node* obj,
+  void g1_write_barrier_pre(bool do_load,
+                            Node* obj,
                             Node* adr,
                             uint alias_idx,
                             Node* val,
                             const TypeOopPtr* val_type,
+                            Node* pre_val,
                             BasicType bt);
 
   void g1_write_barrier_post(Node* store,
--- a/src/share/vm/opto/lcm.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/opto/lcm.cpp	Wed May 04 16:38:05 2011 -0700
@@ -688,20 +688,22 @@
       }
       ready_cnt[n->_idx] = local; // Count em up
 
+#ifdef ASSERT
+      if( UseConcMarkSweepGC || UseG1GC ) {
+        if( n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_StoreCM ) {
+          // Check the precedence edges
+          for (uint prec = n->req(); prec < n->len(); prec++) {
+            Node* oop_store = n->in(prec);
+            if (oop_store != NULL) {
+              assert(cfg->_bbs[oop_store->_idx]->_dom_depth <= this->_dom_depth, "oop_store must dominate card-mark");
+            }
+          }
+        }
+      }
+#endif
+
       // A few node types require changing a required edge to a precedence edge
       // before allocation.
-      if( UseConcMarkSweepGC || UseG1GC ) {
-        if( n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_StoreCM ) {
-          // Note: Required edges with an index greater than oper_input_base
-          // are not supported by the allocator.
-          // Note2: Can only depend on unmatched edge being last,
-          // can not depend on its absolute position.
-          Node *oop_store = n->in(n->req() - 1);
-          n->del_req(n->req() - 1);
-          n->add_prec(oop_store);
-          assert(cfg->_bbs[oop_store->_idx]->_dom_depth <= this->_dom_depth, "oop_store must dominate card-mark");
-        }
-      }
       if( n->is_Mach() && n->req() > TypeFunc::Parms &&
           (n->as_Mach()->ideal_Opcode() == Op_MemBarAcquire ||
            n->as_Mach()->ideal_Opcode() == Op_MemBarVolatile) ) {
--- a/src/share/vm/opto/library_call.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/opto/library_call.cpp	Wed May 04 16:38:05 2011 -0700
@@ -166,6 +166,10 @@
   // This returns Type::AnyPtr, RawPtr, or OopPtr.
   int classify_unsafe_addr(Node* &base, Node* &offset);
   Node* make_unsafe_address(Node* base, Node* offset);
+  // Helper for inline_unsafe_access.
+  // Generates the guards that check whether the result of
+  // Unsafe.getObject should be recorded in an SATB log buffer.
+  void insert_g1_pre_barrier(Node* base_oop, Node* offset, Node* pre_val);
   bool inline_unsafe_access(bool is_native_ptr, bool is_store, BasicType type, bool is_volatile);
   bool inline_unsafe_prefetch(bool is_native_ptr, bool is_store, bool is_static);
   bool inline_unsafe_allocate();
@@ -240,6 +244,8 @@
   bool inline_numberOfTrailingZeros(vmIntrinsics::ID id);
   bool inline_bitCount(vmIntrinsics::ID id);
   bool inline_reverseBytes(vmIntrinsics::ID id);
+
+  bool inline_reference_get();
 };
 
 
@@ -336,6 +342,14 @@
     if (!UsePopCountInstruction)  return NULL;
     break;
 
+  case vmIntrinsics::_Reference_get:
+    // It is only when G1 is enabled that we absolutely
+    // need to use the intrinsic version of Reference.get()
+    // so that the value in the referent field, if necessary,
+    // can be registered by the pre-barrier code.
+    if (!UseG1GC) return NULL;
+    break;
+
  default:
     assert(id <= vmIntrinsics::LAST_COMPILER_INLINE, "caller responsibility");
     assert(id != vmIntrinsics::_Object_init && id != vmIntrinsics::_invoke, "enum out of order?");
@@ -387,6 +401,7 @@
     tty->print_cr("Intrinsic %s", str);
   }
 #endif
+
   if (kit.try_to_inline()) {
     if (PrintIntrinsics || PrintInlining NOT_PRODUCT( || PrintOptoInlining) ) {
       CompileTask::print_inlining(kit.callee(), jvms->depth() - 1, kit.bci(), is_virtual() ? "(intrinsic, virtual)" : "(intrinsic)");
@@ -402,11 +417,19 @@
   }
 
   if (PrintIntrinsics) {
-    tty->print("Did not inline intrinsic %s%s at bci:%d in",
+    if (jvms->has_method()) {
+      // Not a root compile.
+      tty->print("Did not inline intrinsic %s%s at bci:%d in",
+                 vmIntrinsics::name_at(intrinsic_id()),
+                 (is_virtual() ? " (virtual)" : ""), kit.bci());
+      kit.caller()->print_short_name(tty);
+      tty->print_cr(" (%d bytes)", kit.caller()->code_size());
+    } else {
+      // Root compile
+      tty->print("Did not generate intrinsic %s%s at bci:%d in",
                vmIntrinsics::name_at(intrinsic_id()),
                (is_virtual() ? " (virtual)" : ""), kit.bci());
-    kit.caller()->print_short_name(tty);
-    tty->print_cr(" (%d bytes)", kit.caller()->code_size());
+    }
   }
   C->gather_intrinsic_statistics(intrinsic_id(), is_virtual(), Compile::_intrinsic_failed);
   return NULL;
@@ -418,6 +441,14 @@
   const bool is_native_ptr  = true;
   const bool is_static      = true;
 
+  if (!jvms()->has_method()) {
+    // Root JVMState has a null method.
+    assert(map()->memory()->Opcode() == Op_Parm, "");
+    // Insert the memory aliasing node
+    set_all_memory(reset_memory());
+  }
+  assert(merged_memory(), "");
+
   switch (intrinsic_id()) {
   case vmIntrinsics::_hashCode:
     return inline_native_hashcode(intrinsic()->is_virtual(), !is_static);
@@ -658,6 +689,9 @@
   case vmIntrinsics::_getCallerClass:
     return inline_native_Reflection_getCallerClass();
 
+  case vmIntrinsics::_Reference_get:
+    return inline_reference_get();
+
   default:
     // If you get here, it may be that someone has added a new intrinsic
     // to the list in vmSymbols.hpp without implementing it here.
@@ -2076,6 +2110,106 @@
 
 const static BasicType T_ADDRESS_HOLDER = T_LONG;
 
+// Helper that guards and inserts a G1 pre-barrier.
+void LibraryCallKit::insert_g1_pre_barrier(Node* base_oop, Node* offset, Node* pre_val) {
+  assert(UseG1GC, "should not call this otherwise");
+
+  // We could be accessing the referent field of a reference object. If so, when G1
+  // is enabled, we need to log the value in the referent field in an SATB buffer.
+  // This routine performs some compile time filters and generates suitable
+  // runtime filters that guard the pre-barrier code.
+
+  // Some compile time checks.
+
+  // If offset is a constant, is it java_lang_ref_Reference::_reference_offset?
+  const TypeX* otype = offset->find_intptr_t_type();
+  if (otype != NULL && otype->is_con() &&
+      otype->get_con() != java_lang_ref_Reference::referent_offset) {
+    // Constant offset but not the reference_offset so just return
+    return;
+  }
+
+  // We only need to generate the runtime guards for instances.
+  const TypeOopPtr* btype = base_oop->bottom_type()->isa_oopptr();
+  if (btype != NULL) {
+    if (btype->isa_aryptr()) {
+      // Array type so nothing to do
+      return;
+    }
+
+    const TypeInstPtr* itype = btype->isa_instptr();
+    if (itype != NULL) {
+      // Can the klass of base_oop be statically determined
+      // to be _not_ a sub-class of Reference?
+      ciKlass* klass = itype->klass();
+      if (klass->is_subtype_of(env()->Reference_klass()) &&
+          !env()->Reference_klass()->is_subtype_of(klass)) {
+        return;
+      }
+    }
+  }
+
+  // The compile time filters did not reject base_oop/offset so
+  // we need to generate the following runtime filters
+  //
+  // if (offset == java_lang_ref_Reference::_reference_offset) {
+  //   if (base != null) {
+  //     if (klass(base)->reference_type() != REF_NONE)) {
+  //       pre_barrier(_, pre_val, ...);
+  //     }
+  //   }
+  // }
+
+  float likely  = PROB_LIKELY(0.999);
+  float unlikely  = PROB_UNLIKELY(0.999);
+
+  IdealKit ideal(this);
+#define __ ideal.
+
+  const int reference_type_offset = instanceKlass::reference_type_offset_in_bytes() +
+                                        sizeof(oopDesc);
+
+  Node* referent_off = __ ConX(java_lang_ref_Reference::referent_offset);
+
+  __ if_then(offset, BoolTest::eq, referent_off, unlikely); {
+    __ if_then(base_oop, BoolTest::ne, null(), likely); {
+
+      // Update graphKit memory and control from IdealKit.
+      sync_kit(ideal);
+
+      Node* ref_klass_con = makecon(TypeKlassPtr::make(env()->Reference_klass()));
+      Node* is_instof = gen_instanceof(base_oop, ref_klass_con);
+
+      // Update IdealKit memory and control from graphKit.
+      __ sync_kit(this);
+
+      Node* one = __ ConI(1);
+
+      __ if_then(is_instof, BoolTest::eq, one, unlikely); {
+
+        // Update graphKit from IdeakKit.
+        sync_kit(ideal);
+
+        // Use the pre-barrier to record the value in the referent field
+        pre_barrier(false /* do_load */,
+                    __ ctrl(),
+                    NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */,
+                    pre_val /* pre_val */,
+                    T_OBJECT);
+
+        // Update IdealKit from graphKit.
+        __ sync_kit(this);
+
+      } __ end_if(); // _ref_type != ref_none
+    } __ end_if(); // base  != NULL
+  } __ end_if(); // offset == referent_offset
+
+  // Final sync IdealKit and GraphKit.
+  final_sync(ideal);
+#undef __
+}
+
+
 // Interpret Unsafe.fieldOffset cookies correctly:
 extern jlong Unsafe_field_offset_to_byte_offset(jlong field_offset);
 
@@ -2152,9 +2286,11 @@
   // Build address expression.  See the code in inline_unsafe_prefetch.
   Node *adr;
   Node *heap_base_oop = top();
+  Node* offset = top();
+
   if (!is_native_ptr) {
     // The offset is a value produced by Unsafe.staticFieldOffset or Unsafe.objectFieldOffset
-    Node* offset = pop_pair();
+    offset = pop_pair();
     // The base is either a Java object or a value produced by Unsafe.staticFieldBase
     Node* base   = pop();
     // We currently rely on the cookies produced by Unsafe.xxxFieldOffset
@@ -2195,6 +2331,13 @@
   // or Compile::must_alias will throw a diagnostic assert.)
   bool need_mem_bar = (alias_type->adr_type() == TypeOopPtr::BOTTOM);
 
+  // If we are reading the value of the referent field of a Reference
+  // object (either by using Unsafe directly or through reflection)
+  // then, if G1 is enabled, we need to record the referent in an
+  // SATB log buffer using the pre-barrier mechanism.
+  bool need_read_barrier = UseG1GC && !is_native_ptr && !is_store &&
+                           offset != top() && heap_base_oop != top();
+
   if (!is_store && type == T_OBJECT) {
     // Attempt to infer a sharper value type from the offset and base type.
     ciKlass* sharpened_klass = NULL;
@@ -2278,8 +2421,13 @@
     case T_SHORT:
     case T_INT:
     case T_FLOAT:
+      push(p);
+      break;
     case T_OBJECT:
-      push( p );
+      if (need_read_barrier) {
+        insert_g1_pre_barrier(heap_base_oop, offset, p);
+      }
+      push(p);
       break;
     case T_ADDRESS:
       // Cast to an int type.
@@ -2534,7 +2682,10 @@
   case T_OBJECT:
      // reference stores need a store barrier.
     // (They don't if CAS fails, but it isn't worth checking.)
-    pre_barrier(control(), base, adr, alias_idx, newval, value_type->make_oopptr(), T_OBJECT);
+    pre_barrier(true /* do_load*/,
+                control(), base, adr, alias_idx, newval, value_type->make_oopptr(),
+                NULL /* pre_val*/,
+                T_OBJECT);
 #ifdef _LP64
     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
       Node *newval_enc = _gvn.transform(new (C, 2) EncodePNode(newval, newval->bottom_type()->make_narrowoop()));
@@ -5235,3 +5386,44 @@
                     copyfunc_addr, copyfunc_name, adr_type,
                     src_start, dest_start, copy_length XTOP);
 }
+
+//----------------------------inline_reference_get----------------------------
+
+bool LibraryCallKit::inline_reference_get() {
+  const int nargs = 1; // self
+
+  guarantee(java_lang_ref_Reference::referent_offset > 0,
+            "should have already been set");
+
+  int referent_offset = java_lang_ref_Reference::referent_offset;
+
+  // Restore the stack and pop off the argument
+  _sp += nargs;
+  Node *reference_obj = pop();
+
+  // Null check on self without removing any arguments.
+  _sp += nargs;
+  reference_obj = do_null_check(reference_obj, T_OBJECT);
+  _sp -= nargs;;
+
+  if (stopped()) return true;
+
+  Node *adr = basic_plus_adr(reference_obj, reference_obj, referent_offset);
+
+  ciInstanceKlass* klass = env()->Object_klass();
+  const TypeOopPtr* object_type = TypeOopPtr::make_from_klass(klass);
+
+  Node* no_ctrl = NULL;
+  Node *result = make_load(no_ctrl, adr, object_type, T_OBJECT);
+
+  // Use the pre-barrier to record the value in the referent field
+  pre_barrier(false /* do_load */,
+              control(),
+              NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */,
+              result /* pre_val */,
+              T_OBJECT);
+
+  push(result);
+  return true;
+}
+
--- a/src/share/vm/opto/memnode.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/opto/memnode.cpp	Wed May 04 16:38:05 2011 -0700
@@ -2159,9 +2159,12 @@
   Node* mem     = in(MemNode::Memory);
   Node* address = in(MemNode::Address);
 
-  // Back-to-back stores to same address?  Fold em up.
-  // Generally unsafe if I have intervening uses...
-  if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
+  // Back-to-back stores to same address?  Fold em up.  Generally
+  // unsafe if I have intervening uses...  Also disallowed for StoreCM
+  // since they must follow each StoreP operation.  Redundant StoreCMs
+  // are eliminated just before matching in final_graph_reshape.
+  if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address) &&
+      mem->Opcode() != Op_StoreCM) {
     // Looking at a dead closed cycle of memory?
     assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
 
--- a/src/share/vm/opto/output.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/opto/output.cpp	Wed May 04 16:38:05 2011 -0700
@@ -1354,15 +1354,20 @@
         // Check that oop-store precedes the card-mark
         else if( mach->ideal_Opcode() == Op_StoreCM ) {
           uint storeCM_idx = j;
-          Node *oop_store = mach->in(mach->_cnt);  // First precedence edge
-          assert( oop_store != NULL, "storeCM expects a precedence edge");
-          uint i4;
-          for( i4 = 0; i4 < last_inst; ++i4 ) {
-            if( b->_nodes[i4] == oop_store ) break;
+          int count = 0;
+          for (uint prec = mach->req(); prec < mach->len(); prec++) {
+            Node *oop_store = mach->in(prec);  // Precedence edge
+            if (oop_store == NULL) continue;
+            count++;
+            uint i4;
+            for( i4 = 0; i4 < last_inst; ++i4 ) {
+              if( b->_nodes[i4] == oop_store ) break;
+            }
+            // Note: This test can provide a false failure if other precedence
+            // edges have been added to the storeCMNode.
+            assert( i4 == last_inst || i4 < storeCM_idx, "CM card-mark executes before oop-store");
           }
-          // Note: This test can provide a false failure if other precedence
-          // edges have been added to the storeCMNode.
-          assert( i4 == last_inst || i4 < storeCM_idx, "CM card-mark executes before oop-store");
+          assert(count > 0, "storeCM expects at least one precedence edge");
         }
 #endif
 
--- a/src/share/vm/prims/jni.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/prims/jni.cpp	Wed May 04 16:38:05 2011 -0700
@@ -29,6 +29,9 @@
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "interpreter/linkResolver.hpp"
+#ifndef SERIALGC
+#include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
+#endif // SERIALGC
 #include "memory/allocation.inline.hpp"
 #include "memory/gcLocker.inline.hpp"
 #include "memory/oopFactory.hpp"
@@ -1724,6 +1727,26 @@
     o = JvmtiExport::jni_GetField_probe(thread, obj, o, k, fieldID, false);
   }
   jobject ret = JNIHandles::make_local(env, o->obj_field(offset));
+#ifndef SERIALGC
+  // If G1 is enabled and we are accessing the value of the referent
+  // field in a reference object then we need to register a non-null
+  // referent with the SATB barrier.
+  if (UseG1GC) {
+    bool needs_barrier = false;
+
+    if (ret != NULL &&
+        offset == java_lang_ref_Reference::referent_offset &&
+        instanceKlass::cast(k)->reference_type() != REF_NONE) {
+      assert(instanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
+      needs_barrier = true;
+    }
+
+    if (needs_barrier) {
+      oop referent = JNIHandles::resolve(ret);
+      G1SATBCardTableModRefBS::enqueue(referent);
+    }
+  }
+#endif // SERIALGC
   DTRACE_PROBE1(hotspot_jni, GetObjectField__return, ret);
   return ret;
 JNI_END
--- a/src/share/vm/prims/jvmtiEnv.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/prims/jvmtiEnv.cpp	Wed May 04 16:38:05 2011 -0700
@@ -525,7 +525,7 @@
     ObjectLocker ol(loader, THREAD);
 
     // need the path as java.lang.String
-    Handle path = java_lang_String::create_from_str(segment, THREAD);
+    Handle path = java_lang_String::create_from_platform_dependent_str(segment, THREAD);
     if (HAS_PENDING_EXCEPTION) {
       CLEAR_PENDING_EXCEPTION;
       return JVMTI_ERROR_INTERNAL;
--- a/src/share/vm/prims/unsafe.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/prims/unsafe.cpp	Wed May 04 16:38:05 2011 -0700
@@ -24,6 +24,9 @@
 
 #include "precompiled.hpp"
 #include "classfile/vmSymbols.hpp"
+#ifndef SERIALGC
+#include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
+#endif // SERIALGC
 #include "memory/allocation.inline.hpp"
 #include "prims/jni.h"
 #include "prims/jvm.h"
@@ -193,7 +196,32 @@
   UnsafeWrapper("Unsafe_GetObject");
   if (obj == NULL)  THROW_0(vmSymbols::java_lang_NullPointerException());
   GET_OOP_FIELD(obj, offset, v)
-  return JNIHandles::make_local(env, v);
+  jobject ret = JNIHandles::make_local(env, v);
+#ifndef SERIALGC
+  // We could be accessing the referent field in a reference
+  // object. If G1 is enabled then we need to register a non-null
+  // referent with the SATB barrier.
+  if (UseG1GC) {
+    bool needs_barrier = false;
+
+    if (ret != NULL) {
+      if (offset == java_lang_ref_Reference::referent_offset) {
+        oop o = JNIHandles::resolve_non_null(obj);
+        klassOop k = o->klass();
+        if (instanceKlass::cast(k)->reference_type() != REF_NONE) {
+          assert(instanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
+          needs_barrier = true;
+        }
+      }
+    }
+
+    if (needs_barrier) {
+      oop referent = JNIHandles::resolve(ret);
+      G1SATBCardTableModRefBS::enqueue(referent);
+    }
+  }
+#endif // SERIALGC
+  return ret;
 UNSAFE_END
 
 UNSAFE_ENTRY(void, Unsafe_SetObject140(JNIEnv *env, jobject unsafe, jobject obj, jint offset, jobject x_h))
@@ -226,7 +254,32 @@
 UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset))
   UnsafeWrapper("Unsafe_GetObject");
   GET_OOP_FIELD(obj, offset, v)
-  return JNIHandles::make_local(env, v);
+  jobject ret = JNIHandles::make_local(env, v);
+#ifndef SERIALGC
+  // We could be accessing the referent field in a reference
+  // object. If G1 is enabled then we need to register non-null
+  // referent with the SATB barrier.
+  if (UseG1GC) {
+    bool needs_barrier = false;
+
+    if (ret != NULL) {
+      if (offset == java_lang_ref_Reference::referent_offset && obj != NULL) {
+        oop o = JNIHandles::resolve(obj);
+        klassOop k = o->klass();
+        if (instanceKlass::cast(k)->reference_type() != REF_NONE) {
+          assert(instanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
+          needs_barrier = true;
+        }
+      }
+    }
+
+    if (needs_barrier) {
+      oop referent = JNIHandles::resolve(ret);
+      G1SATBCardTableModRefBS::enqueue(referent);
+    }
+  }
+#endif // SERIALGC
+  return ret;
 UNSAFE_END
 
 UNSAFE_ENTRY(void, Unsafe_SetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h))
--- a/src/share/vm/runtime/arguments.cpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/runtime/arguments.cpp	Wed May 04 16:38:05 2011 -0700
@@ -244,6 +244,12 @@
   { "MaxLiveObjectEvacuationRatio",
                            JDK_Version::jdk_update(6,24), JDK_Version::jdk(8) },
   { "ForceSharedSpaces",   JDK_Version::jdk_update(6,25), JDK_Version::jdk(8) },
+  { "UseParallelOldGCCompacting",
+                           JDK_Version::jdk_update(6,27), JDK_Version::jdk(8) },
+  { "UseParallelDensePrefixUpdate",
+                           JDK_Version::jdk_update(6,27), JDK_Version::jdk(8) },
+  { "UseParallelOldGCDensePrefix",
+                           JDK_Version::jdk_update(6,27), JDK_Version::jdk(8) },
   { "AllowTransitionalJSR292",       JDK_Version::jdk(7), JDK_Version::jdk(8) },
   { NULL, JDK_Version(0), JDK_Version(0) }
 };
@@ -801,26 +807,22 @@
 
   JDK_Version since = JDK_Version();
 
-  if (parse_argument(arg, origin)) {
-    // do nothing
-  } else if (is_newly_obsolete(arg, &since)) {
-    enum { bufsize = 256 };
-    char buffer[bufsize];
-    since.to_string(buffer, bufsize);
-    jio_fprintf(defaultStream::error_stream(),
-      "Warning: The flag %s has been EOL'd as of %s and will"
-      " be ignored\n", arg, buffer);
-  } else {
-    if (!ignore_unrecognized) {
-      jio_fprintf(defaultStream::error_stream(),
-                  "Unrecognized VM option '%s'\n", arg);
-      // allow for commandline "commenting out" options like -XX:#+Verbose
-      if (strlen(arg) == 0 || arg[0] != '#') {
-        return false;
-      }
-    }
+  if (parse_argument(arg, origin) || ignore_unrecognized) {
+    return true;
   }
-  return true;
+
+  const char * const argname = *arg == '+' || *arg == '-' ? arg + 1 : arg;
+  if (is_newly_obsolete(arg, &since)) {
+    char version[256];
+    since.to_string(version, sizeof(version));
+    warning("ignoring option %s; support was removed in %s", argname, version);
+    return true;
+  }
+
+  jio_fprintf(defaultStream::error_stream(),
+              "Unrecognized VM option '%s'\n", argname);
+  // allow for commandline "commenting out" options like -XX:#+Verbose
+  return arg[0] == '#';
 }
 
 bool Arguments::process_settings_file(const char* file_name, bool should_exist, jboolean ignore_unrecognized) {
--- a/src/share/vm/runtime/globals.hpp	Fri Apr 15 09:34:43 2011 -0400
+++ b/src/share/vm/runtime/globals.hpp	Wed May 04 16:38:05 2011 -0700
@@ -1355,13 +1355,6 @@
   product(bool, UseParallelOldGC, false,                                    \
           "Use the Parallel Old garbage collector")                         \
                                                                             \
-  product(bool, UseParallelOldGCCompacting, true,                           \
-          "In the Parallel Old garbage collector use parallel compaction")  \
-                                                                            \
-  product(bool, UseParallelDensePrefixUpdate, true,                         \
-          "In the Parallel Old garbage collector use parallel dense"        \
-          " prefix update")                                                 \
-                                                                            \
   product(uintx, HeapMaximumCompactionInterval, 20,                         \
           "How often should we maximally compact the heap (not allowing "   \
           "any dead space)")                                                \
@@ -1381,9 +1374,6 @@
           "The standard deviation used by the par compact dead wood"        \
           "limiter (a number between 0-100).")                              \
                                                                             \
-  product(bool, UseParallelOldGCDensePrefix, true,                          \
-          "Use a dense prefix with the Parallel Old garbage collector")     \
-                                                                            \
   product(uintx, ParallelGCThreads, 0,                                      \
           "Number of parallel threads parallel gc will use")                \
                                                                             \