--- /dev/null	2017-03-07 11:44:12.271151064 +0100
+++ new/src/cpu/sparc/vm/gc/g1/g1BSCodeGen_sparc.cpp	2017-04-25 16:45:59.651172244 +0200
@@ -0,0 +1,695 @@
+/*
+ * Copyright (c) 2016, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "asm/macroAssembler.inline.hpp"
+#include "c1/c1_LIRAssembler.hpp"
+#include "c1/c1_MacroAssembler.hpp"
+#include "gc/g1/c1G1BSCodeGen.hpp"
+#include "gc/g1/g1BarrierSet.hpp"
+#include "gc/g1/g1CardTable.hpp"
+#include "gc/g1/g1BSCodeGen.hpp"
+#include "gc/g1/heapRegion.hpp"
+#include "gc/shared/collectedHeap.hpp"
+#include "runtime/thread.hpp"
+#include "interpreter/interp_masm.hpp"
+
+#define __ masm->
+
+void G1BSCodeGen::gen_write_ref_array_pre_barrier(MacroAssembler* masm, DecoratorSet decorators, Register addr, Register count) {
+  bool dest_uninitialized = (decorators & DEST_NOT_INITIALIZED) != 0;
+  // With G1, don't generate the call if we statically know that the target in uninitialized
+  if (!dest_uninitialized) {
+    __ save_frame(0);
+    // Save the necessary global regs... will be used after.
+    if (addr->is_global()) {
+      __ mov(addr, L0);
+    }
+    if (count->is_global()) {
+      __ mov(count, L1);
+    }
+    __ mov(addr->after_save(), O0);
+    // Get the count into O1
+    __ call(CAST_FROM_FN_PTR(address, ModRefBarrierSet::static_write_ref_array_pre));
+    __ delayed()->mov(count->after_save(), O1);
+    if (addr->is_global()) {
+      __ mov(L0, addr);
+    }
+    if (count->is_global()) {
+      __ mov(L1, count);
+    }
+    __ restore();
+  }
+}
+
+void G1BSCodeGen::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators, Register addr, Register count, Register tmp) {
+  // Get some new fresh output registers.
+  __ save_frame(0);
+  __ mov(addr->after_save(), O0);
+  __ call(CAST_FROM_FN_PTR(address, ModRefBarrierSet::static_write_ref_array_post));
+  __ delayed()->mov(count->after_save(), O1);
+  __ restore();
+}
+
+#undef __
+
+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?
+
+static void generate_satb_log_enqueue(bool with_frame) {
+  BufferBlob* bb = BufferBlob::create("enqueue_with_frame", EnqueueCodeSize);
+  CodeBuffer buf(bb);
+  MacroAssembler masm(&buf);
+
+#define __ masm.
+
+  address start = __ pc();
+  Register pre_val;
+
+  Label refill, restart;
+  if (with_frame) {
+    __ save_frame(0);
+    pre_val = I0;  // Was O0 before the save.
+  } else {
+    pre_val = O0;
+  }
+
+  int satb_q_index_byte_offset =
+    in_bytes(JavaThread::satb_mark_queue_offset() +
+             SATBMarkQueue::byte_offset_of_index());
+
+  int satb_q_buf_byte_offset =
+    in_bytes(JavaThread::satb_mark_queue_offset() +
+             SATBMarkQueue::byte_offset_of_buf());
+
+  assert(in_bytes(SATBMarkQueue::byte_width_of_index()) == sizeof(intptr_t) &&
+         in_bytes(SATBMarkQueue::byte_width_of_buf()) == sizeof(intptr_t),
+         "check sizes in assembly below");
+
+  __ bind(restart);
+
+  // Load the index into the SATB buffer. SATBMarkQueue::_index is a size_t
+  // so ld_ptr is appropriate.
+  __ ld_ptr(G2_thread, satb_q_index_byte_offset, L0);
+
+  // index == 0?
+  __ cmp_and_brx_short(L0, G0, Assembler::equal, Assembler::pn, refill);
+
+  __ ld_ptr(G2_thread, satb_q_buf_byte_offset, L1);
+  __ sub(L0, oopSize, L0);
+
+  __ st_ptr(pre_val, L1, L0);  // [_buf + index] := I0
+  if (!with_frame) {
+    // Use return-from-leaf
+    __ retl();
+    __ delayed()->st_ptr(L0, G2_thread, satb_q_index_byte_offset);
+  } else {
+    // Not delayed.
+    __ st_ptr(L0, G2_thread, satb_q_index_byte_offset);
+  }
+  if (with_frame) {
+    __ ret();
+    __ delayed()->restore();
+  }
+  __ bind(refill);
+
+  address handle_zero =
+    CAST_FROM_FN_PTR(address,
+                     &SATBMarkQueueSet::handle_zero_index_for_thread);
+  // This should be rare enough that we can afford to save all the
+  // scratch registers that the calling context might be using.
+  __ mov(G1_scratch, L0);
+  __ mov(G3_scratch, L1);
+  __ mov(G4, L2);
+  // We need the value of O0 above (for the write into the buffer), so we
+  // save and restore it.
+  __ mov(O0, L3);
+  // Since the call will overwrite O7, we save and restore that, as well.
+  __ mov(O7, L4);
+  __ call_VM_leaf(L5, handle_zero, G2_thread);
+  __ mov(L0, G1_scratch);
+  __ mov(L1, G3_scratch);
+  __ mov(L2, G4);
+  __ mov(L3, O0);
+  __ br(Assembler::always, /*annul*/false, Assembler::pt, restart);
+  __ delayed()->mov(L4, O7);
+
+  if (with_frame) {
+    satb_log_enqueue_with_frame = start;
+    satb_log_enqueue_with_frame_end = __ pc();
+  } else {
+    satb_log_enqueue_frameless = start;
+    satb_log_enqueue_frameless_end = __ pc();
+  }
+
+#undef __
+}
+
+static inline void generate_satb_log_enqueue_if_necessary(bool with_frame) {
+  if (with_frame) {
+    if (satb_log_enqueue_with_frame == 0) {
+      generate_satb_log_enqueue(with_frame);
+      assert(satb_log_enqueue_with_frame != 0, "postcondition.");
+    }
+  } else {
+    if (satb_log_enqueue_frameless == 0) {
+      generate_satb_log_enqueue(with_frame);
+      assert(satb_log_enqueue_frameless != 0, "postcondition.");
+    }
+  }
+}
+
+#define __ masm->
+
+void G1BSCodeGen::g1_write_barrier_pre(MacroAssembler* masm,
+                                       Register obj,
+                                       Register index,
+                                       int offset,
+                                       Register pre_val,
+                                       Register tmp,
+                                       bool preserve_o_regs) {
+  Label 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(SATBMarkQueue::byte_width_of_active()) == 4) {
+    __ ld(G2,
+          in_bytes(JavaThread::satb_mark_queue_offset() +
+                   SATBMarkQueue::byte_offset_of_active()),
+          tmp);
+  } else {
+    guarantee(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1,
+              "Assumption");
+    __ ldsb(G2,
+            in_bytes(JavaThread::satb_mark_queue_offset() +
+                     SATBMarkQueue::byte_offset_of_active()),
+            tmp);
+  }
+
+  // Is marking active?
+  __ cmp_and_br_short(tmp, G0, Assembler::equal, Assembler::pt, filtered);
+
+  // 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 {
+      __ load_heap_oop(obj, index, tmp);
+    }
+    // Previous value has been loaded into tmp
+    pre_val = tmp;
+  }
+
+  assert(pre_val != noreg, "must have a real register");
+
+  // Is the previous value null?
+  __ cmp_and_brx_short(pre_val, G0, Assembler::equal, Assembler::pt, filtered);
+
+  // 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 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
+
+    __ call(satb_log_enqueue_with_frame);
+    __ delayed()->mov(pre_val, O0);
+  } else {
+    generate_satb_log_enqueue_if_necessary(false); // frameless
+
+    __ save_frame(0);
+    __ call(satb_log_enqueue_frameless);
+    __ delayed()->mov(pre_val->after_save(), O0);
+    __ restore();
+  }
+
+  __ bind(filtered);
+}
+
+#undef __
+
+static address dirty_card_log_enqueue = 0;
+static u_char* dirty_card_log_enqueue_end = 0;
+
+// This gets to assume that o0 contains the object address.
+static void generate_dirty_card_log_enqueue(jbyte* byte_map_base) {
+  BufferBlob* bb = BufferBlob::create("dirty_card_enqueue", EnqueueCodeSize*2);
+  CodeBuffer buf(bb);
+  MacroAssembler masm(&buf);
+#define __ masm.
+  address start = __ pc();
+
+  Label not_already_dirty, restart, refill, young_card;
+
+#ifdef _LP64
+  __ srlx(O0, CardTable::card_shift, O0);
+#else
+  __ srl(O0, CardTable::card_shift, O0);
+#endif
+  AddressLiteral addrlit((address)byte_map_base);
+  __ set(addrlit, O1); // O1 := <card table base>
+  __ ldub(O0, O1, O2); // O2 := [O0 + O1]
+
+  __ cmp_and_br_short(O2, G1CardTable::g1_young_card_val(), Assembler::equal, Assembler::pt, young_card);
+
+  __ membar(Assembler::Membar_mask_bits(Assembler::StoreLoad));
+  __ ldub(O0, O1, O2); // O2 := [O0 + O1]
+
+  assert(G1CardTable::dirty_card_val() == 0, "otherwise check this code");
+  __ cmp_and_br_short(O2, G0, Assembler::notEqual, Assembler::pt, not_already_dirty);
+
+  __ bind(young_card);
+  // We didn't take the branch, so we're already dirty: return.
+  // Use return-from-leaf
+  __ retl();
+  __ delayed()->nop();
+
+  // Not dirty.
+  __ bind(not_already_dirty);
+
+  // Get O0 + O1 into a reg by itself
+  __ add(O0, O1, O3);
+
+  // First, dirty it.
+  __ stb(G0, O3, G0);  // [cardPtr] := 0  (i.e., dirty).
+
+  int dirty_card_q_index_byte_offset =
+    in_bytes(JavaThread::dirty_card_queue_offset() +
+             DirtyCardQueue::byte_offset_of_index());
+  int dirty_card_q_buf_byte_offset =
+    in_bytes(JavaThread::dirty_card_queue_offset() +
+             DirtyCardQueue::byte_offset_of_buf());
+  __ bind(restart);
+
+  // Load the index into the update buffer. DirtyCardQueue::_index is
+  // a size_t so ld_ptr is appropriate here.
+  __ ld_ptr(G2_thread, dirty_card_q_index_byte_offset, L0);
+
+  // index == 0?
+  __ cmp_and_brx_short(L0, G0, Assembler::equal, Assembler::pn, refill);
+
+  __ ld_ptr(G2_thread, dirty_card_q_buf_byte_offset, L1);
+  __ sub(L0, oopSize, L0);
+
+  __ st_ptr(O3, L1, L0);  // [_buf + index] := I0
+  // Use return-from-leaf
+  __ retl();
+  __ delayed()->st_ptr(L0, G2_thread, dirty_card_q_index_byte_offset);
+
+  __ bind(refill);
+  address handle_zero =
+    CAST_FROM_FN_PTR(address,
+                     &DirtyCardQueueSet::handle_zero_index_for_thread);
+  // This should be rare enough that we can afford to save all the
+  // scratch registers that the calling context might be using.
+  __ mov(G1_scratch, L3);
+  __ mov(G3_scratch, L5);
+  // We need the value of O3 above (for the write into the buffer), so we
+  // save and restore it.
+  __ mov(O3, L6);
+  // Since the call will overwrite O7, we save and restore that, as well.
+  __ mov(O7, L4);
+
+  __ call_VM_leaf(L7_thread_cache, handle_zero, G2_thread);
+  __ mov(L3, G1_scratch);
+  __ mov(L5, G3_scratch);
+  __ mov(L6, O3);
+  __ br(Assembler::always, /*annul*/false, Assembler::pt, restart);
+  __ delayed()->mov(L4, O7);
+
+  dirty_card_log_enqueue = start;
+  dirty_card_log_enqueue_end = __ pc();
+  // XXX Should have a guarantee here about not going off the end!
+  // Does it already do so?  Do an experiment...
+
+#undef __
+
+}
+
+static inline void
+generate_dirty_card_log_enqueue_if_necessary(jbyte* byte_map_base) {
+  if (dirty_card_log_enqueue == 0) {
+    generate_dirty_card_log_enqueue(byte_map_base);
+    assert(dirty_card_log_enqueue != 0, "postcondition.");
+  }
+}
+
+#define __ masm->
+
+void G1BSCodeGen::g1_write_barrier_post(MacroAssembler* masm, Register store_addr, Register new_val, Register tmp) {
+  Label filtered;
+  MacroAssembler* post_filter_masm = masm;
+
+  if (new_val == G0) return;
+
+  G1BarrierSet* bs =
+    barrier_set_cast<G1BarrierSet>(Universe::heap()->barrier_set());
+
+  if (G1RSBarrierRegionFilter) {
+    __ xor3(store_addr, new_val, tmp);
+#ifdef _LP64
+    __ srlx(tmp, HeapRegion::LogOfHRGrainBytes, tmp);
+#else
+    __ srl(tmp, HeapRegion::LogOfHRGrainBytes, tmp);
+#endif
+
+    __ cmp_and_brx_short(tmp, G0, Assembler::equal, Assembler::pt, filtered);
+  }
+
+  // If the "store_addr" register is an "in" or "local" register, move it to
+  // a scratch reg so we can pass it as an argument.
+  bool use_scr = !(store_addr->is_global() || store_addr->is_out());
+  // Pick a scratch register different from "tmp".
+  Register scr = (tmp == G1_scratch ? G3_scratch : G1_scratch);
+  // Make sure we use up the delay slot!
+  if (use_scr) {
+    post_filter_masm->mov(store_addr, scr);
+  } else {
+    post_filter_masm->nop();
+  }
+  generate_dirty_card_log_enqueue_if_necessary(bs->card_table()->byte_map_base());
+  __ save_frame(0);
+  __ call(dirty_card_log_enqueue);
+  if (use_scr) {
+    __ delayed()->mov(scr, O0);
+  } else {
+    __ delayed()->mov(store_addr->after_save(), O0);
+  }
+  __ restore();
+
+  __ bind(filtered);
+}
+
+void G1BSCodeGen::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
+                                            Register base, Register index, int offset, Register val, Register tmp) {
+  bool on_array = (decorators & ACCESS_ON_ARRAY) != 0;
+  bool on_anonymous = (decorators & ACCESS_ON_ANONYMOUS) != 0;
+  bool precise = on_array || on_anonymous;
+  // Load and record the previous value.
+  g1_write_barrier_pre(masm, base, index, offset,
+                       noreg /* pre_val */,
+                       tmp, true /*preserve_o_regs*/);
+
+  // G1 barrier needs uncompressed oop for region cross check.
+  Register new_val = val;
+  if (UseCompressedOops && val != G0) {
+    new_val = tmp;
+    __ mov(val, new_val);
+  }
+
+  BarrierSetCodeGen::store_at(masm, decorators, type, base, index, offset, val, tmp);
+
+  // No need for post barrier if storing NULL
+  if (val != G0) {
+    if (precise) {
+      if (index == noreg) {
+        __ add(base, offset, base);
+      } else {
+        __ add(base, index, base);
+      }
+    }
+    g1_write_barrier_post(masm, base, new_val, tmp);
+  }
+}
+
+void G1BSCodeGen::load_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
+                          Register base, Register index, int offset, Register dst, Register tmp) {
+  bool on_oop = type == T_OBJECT || type == T_ARRAY;
+  bool on_weak = (decorators & GC_ACCESS_ON_WEAK) != 0;
+  bool on_phantom = (decorators & GC_ACCESS_ON_PHANTOM) != 0;
+  bool on_reference = on_weak || on_phantom;
+  // Load the value of the referent field.
+  ModRefBSCodeGen::load_at(masm, decorators, type, base, index, offset, dst, tmp);
+  if (on_oop && on_reference) {
+    // 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(masm, noreg /* obj */, noreg /* index */, 0 /* offset */,
+                         dst /* pre_val */,
+                         tmp /* tmp */,
+                         true /* preserve_o_regs */);
+  }
+}
+
+#undef __
+#define __ ce->masm()->
+
+void G1BSCodeGen::gen_g1_pre_barrier_stub(LIR_Assembler* ce, G1PreBarrierStub* stub) {
+  C1G1BSCodeGen* code_gen = (C1G1BSCodeGen*)Universe::heap()->barrier_set()->c1_code_gen();
+  // 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(stub->_entry);
+
+  assert(stub->pre_val()->is_register(), "Precondition.");
+  Register pre_val_reg = stub->pre_val()->as_register();
+
+  if (stub->do_load()) {
+    ce->mem2reg(stub->addr(), stub->pre_val(), T_OBJECT, stub->patch_code(), stub->info(), false /*wide*/, false /*unaligned*/);
+  }
+
+  if (__ is_in_wdisp16_range(stub->_continuation)) {
+    __ br_null(pre_val_reg, /*annul*/false, Assembler::pt, stub->_continuation);
+  } else {
+    __ cmp(pre_val_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pn, stub->_continuation);
+  }
+  __ delayed()->nop();
+
+  __ call(code_gen->pre_barrier_c1_runtime_code_blob()->code_begin());
+  __ delayed()->mov(pre_val_reg, G4);
+  __ br(Assembler::always, false, Assembler::pt, stub->_continuation);
+  __ delayed()->nop();
+}
+
+void G1BSCodeGen::gen_g1_post_barrier_stub(LIR_Assembler* ce, G1PostBarrierStub* stub) {
+  C1G1BSCodeGen* code_gen = (C1G1BSCodeGen*)Universe::heap()->barrier_set()->c1_code_gen();
+  __ bind(stub->_entry);
+
+  assert(stub->addr()->is_register(), "Precondition.");
+  assert(stub->new_val()->is_register(), "Precondition.");
+  Register addr_reg = stub->addr()->as_pointer_register();
+  Register new_val_reg = stub->new_val()->as_register();
+
+  if (__ is_in_wdisp16_range(stub->_continuation)) {
+    __ br_null(new_val_reg, /*annul*/false, Assembler::pt, stub->_continuation);
+  } else {
+    __ cmp(new_val_reg, G0);
+    __ brx(Assembler::equal, false, Assembler::pn, stub->_continuation);
+  }
+  __ delayed()->nop();
+
+  __ call(code_gen->post_barrier_c1_runtime_code_blob()->code_begin());
+  __ delayed()->mov(addr_reg, G4);
+  __ br(Assembler::always, false, Assembler::pt, stub->_continuation);
+  __ delayed()->nop();
+}
+
+#undef __
+#define __ sasm->
+
+void G1BSCodeGen::generate_c1_pre_barrier_runtime_stub(StubAssembler* sasm) {
+  __ prologue("g1_pre_barrier", false);
+
+  // G4: previous value of memory
+
+  Register pre_val = G4;
+  Register tmp  = G1_scratch;
+  Register tmp2 = G3_scratch;
+
+  Label refill, restart;
+  int satb_q_active_byte_offset =
+    in_bytes(JavaThread::satb_mark_queue_offset() +
+             SATBMarkQueue::byte_offset_of_active());
+  int satb_q_index_byte_offset =
+    in_bytes(JavaThread::satb_mark_queue_offset() +
+             SATBMarkQueue::byte_offset_of_index());
+  int satb_q_buf_byte_offset =
+    in_bytes(JavaThread::satb_mark_queue_offset() +
+             SATBMarkQueue::byte_offset_of_buf());
+
+  // Is marking still active?
+  if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {
+    __ ld(G2_thread, satb_q_active_byte_offset, tmp);
+  } else {
+    assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");
+    __ ldsb(G2_thread, satb_q_active_byte_offset, tmp);
+  }
+  __ cmp_and_br_short(tmp, G0, Assembler::notEqual, Assembler::pt, restart);
+  __ retl();
+  __ delayed()->nop();
+
+  __ bind(restart);
+  // Load the index into the SATB buffer. SATBMarkQueue::_index is a
+  // size_t so ld_ptr is appropriate
+  __ ld_ptr(G2_thread, satb_q_index_byte_offset, tmp);
+
+  // index == 0?
+  __ cmp_and_brx_short(tmp, G0, Assembler::equal, Assembler::pn, refill);
+
+  __ ld_ptr(G2_thread, satb_q_buf_byte_offset, tmp2);
+  __ sub(tmp, oopSize, tmp);
+
+  __ st_ptr(pre_val, tmp2, tmp);  // [_buf + index] := <address_of_card>
+  // Use return-from-leaf
+  __ retl();
+  __ delayed()->st_ptr(tmp, G2_thread, satb_q_index_byte_offset);
+
+  __ bind(refill);
+
+  __ save_live_registers_no_oop_map(true);
+
+  __ call_VM_leaf(L7_thread_cache,
+                  CAST_FROM_FN_PTR(address,
+                                   SATBMarkQueueSet::handle_zero_index_for_thread),
+                                   G2_thread);
+
+  __ restore_live_registers(true);
+
+  __ br(Assembler::always, /*annul*/false, Assembler::pt, restart);
+  __ epilogue();
+}
+
+void G1BSCodeGen::generate_c1_post_barrier_runtime_stub(StubAssembler* sasm) {
+  __ prologue("g1_post_barrier", false);
+
+  G1BarrierSet* bs = barrier_set_cast<G1BarrierSet>(Universe::heap()->barrier_set());
+
+  Register addr = G4;
+  Register cardtable = G5;
+  Register tmp  = G1_scratch;
+  Register tmp2 = G3_scratch;
+  jbyte* byte_map_base = bs->card_table()->byte_map_base();
+
+  Label not_already_dirty, restart, refill, young_card;
+
+#ifdef _LP64
+  __ srlx(addr, CardTable::card_shift, addr);
+#else
+  __ srl(addr, CardTable::card_shift, addr);
+#endif
+
+  AddressLiteral rs((address)byte_map_base);
+  __ set(rs, cardtable);         // cardtable := <card table base>
+  __ ldub(addr, cardtable, tmp); // tmp := [addr + cardtable]
+
+  __ cmp_and_br_short(tmp, G1CardTable::g1_young_card_val(), Assembler::equal, Assembler::pt, young_card);
+
+  __ membar(Assembler::Membar_mask_bits(Assembler::StoreLoad));
+  __ ldub(addr, cardtable, tmp); // tmp := [addr + cardtable]
+
+  assert(G1CardTable::dirty_card_val() == 0, "otherwise check this code");
+  __ cmp_and_br_short(tmp, G0, Assembler::notEqual, Assembler::pt, not_already_dirty);
+
+  __ bind(young_card);
+  // We didn't take the branch, so we're already dirty: return.
+  // Use return-from-leaf
+  __ retl();
+  __ delayed()->nop();
+
+  // Not dirty.
+  __ bind(not_already_dirty);
+
+  // Get cardtable + tmp into a reg by itself
+  __ add(addr, cardtable, tmp2);
+
+  // First, dirty it.
+  __ stb(G0, tmp2, 0);  // [cardPtr] := 0  (i.e., dirty).
+
+  Register tmp3 = cardtable;
+  Register tmp4 = tmp;
+
+  // these registers are now dead
+  addr = cardtable = tmp = noreg;
+
+  int dirty_card_q_index_byte_offset =
+    in_bytes(JavaThread::dirty_card_queue_offset() +
+             DirtyCardQueue::byte_offset_of_index());
+  int dirty_card_q_buf_byte_offset =
+    in_bytes(JavaThread::dirty_card_queue_offset() +
+             DirtyCardQueue::byte_offset_of_buf());
+
+  __ bind(restart);
+
+  // Get the index into the update buffer. DirtyCardQueue::_index is
+  // a size_t so ld_ptr is appropriate here.
+  __ ld_ptr(G2_thread, dirty_card_q_index_byte_offset, tmp3);
+
+  // index == 0?
+  __ cmp_and_brx_short(tmp3, G0, Assembler::equal,  Assembler::pn, refill);
+
+  __ ld_ptr(G2_thread, dirty_card_q_buf_byte_offset, tmp4);
+  __ sub(tmp3, oopSize, tmp3);
+
+  __ st_ptr(tmp2, tmp4, tmp3);  // [_buf + index] := <address_of_card>
+  // Use return-from-leaf
+  __ retl();
+  __ delayed()->st_ptr(tmp3, G2_thread, dirty_card_q_index_byte_offset);
+
+  __ bind(refill);
+
+  __ save_live_registers_no_oop_map(true);
+
+  __ call_VM_leaf(L7_thread_cache,
+                  CAST_FROM_FN_PTR(address,
+                                   DirtyCardQueueSet::handle_zero_index_for_thread),
+                                   G2_thread);
+
+  __ restore_live_registers(true);
+
+  __ br(Assembler::always, /*annul*/false, Assembler::pt, restart);
+  __ epilogue();
+}
+
+#undef __