--- old/src/cpu/aarch64/vm/macroAssembler_aarch64.cpp	2015-05-06 19:23:48.249544656 +0300
+++ new/src/cpu/aarch64/vm/macroAssembler_aarch64.cpp	2015-05-06 19:23:48.197548122 +0300
@@ -2888,41 +2888,40 @@
   cmp(src1, rscratch1);
 }
 
-void MacroAssembler::store_check(Register obj) {
-  // Does a store check for the oop in register obj. The content of
-  // register obj is destroyed afterwards.
-  store_check_part_1(obj);
-  store_check_part_2(obj);
-}
-
 void MacroAssembler::store_check(Register obj, Address dst) {
   store_check(obj);
 }
 
+void MacroAssembler::store_check(Register obj) {
+  // Does a store check for the oop in register obj. The content of
+  // register obj is destroyed afterwards.
 
-// split the store check operation so that other instructions can be scheduled inbetween
-void MacroAssembler::store_check_part_1(Register obj) {
   BarrierSet* bs = Universe::heap()->barrier_set();
   assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
-  lsr(obj, obj, CardTableModRefBS::card_shift);
-}
 
-void MacroAssembler::store_check_part_2(Register obj) {
-  BarrierSet* bs = Universe::heap()->barrier_set();
-  assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
-  CardTableModRefBS* ct = (CardTableModRefBS*)bs;
+  CardTableModRefBS* ct = barrier_set_cast<CardTableModRefBS>(bs);
   assert(sizeof(*ct->byte_map_base) == sizeof(jbyte), "adjust this code");
 
-  // The calculation for byte_map_base is as follows:
-  // byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
-  // So this essentially converts an address to a displacement and
-  // it will never need to be relocated.
-
-  // FIXME: It's not likely that disp will fit into an offset so we
-  // don't bother to check, but it could save an instruction.
-  intptr_t disp = (intptr_t) ct->byte_map_base;
-  mov(rscratch1, disp);
-  strb(zr, Address(obj, rscratch1));
+  lsr(obj, obj, CardTableModRefBS::card_shift);
+
+  assert(CardTableModRefBS::dirty_card_val() == 0, "must be");
+
+  {
+    ExternalAddress cardtable((address) ct->byte_map_base);
+    unsigned long offset;
+    adrp(rscratch1, cardtable, offset);
+    assert(offset == 0, "byte_map_base is misaligned");
+  }
+
+  if (UseCondCardMark) {
+    Label L_already_dirty;
+    ldrb(rscratch2,  Address(obj, rscratch1));
+    cbz(rscratch2, L_already_dirty);
+    strb(zr, Address(obj, rscratch1));
+    bind(L_already_dirty);
+  } else {
+    strb(zr, Address(obj, rscratch1));
+  }
 }
 
 void MacroAssembler::load_klass(Register dst, Register src) {
--- old/src/cpu/aarch64/vm/macroAssembler_aarch64.hpp	2015-05-06 19:23:48.501527846 +0300
+++ new/src/cpu/aarch64/vm/macroAssembler_aarch64.hpp	2015-05-06 19:23:48.449531317 +0300
@@ -704,10 +704,6 @@
 
 #endif // INCLUDE_ALL_GCS
 
-  // split store_check(Register obj) to enhance instruction interleaving
-  void store_check_part_1(Register obj);
-  void store_check_part_2(Register obj);
-
   // oop manipulations
   void load_klass(Register dst, Register src);
   void store_klass(Register dst, Register src);
--- old/src/cpu/x86/vm/macroAssembler_x86.cpp	2015-05-06 19:23:48.729512639 +0300
+++ new/src/cpu/x86/vm/macroAssembler_x86.cpp	2015-05-06 19:23:48.673516374 +0300
@@ -4297,31 +4297,24 @@
 //////////////////////////////////////////////////////////////////////////////////
 
 
-void MacroAssembler::store_check(Register obj) {
-  // Does a store check for the oop in register obj. The content of
-  // register obj is destroyed afterwards.
-  store_check_part_1(obj);
-  store_check_part_2(obj);
-}
-
 void MacroAssembler::store_check(Register obj, Address dst) {
   store_check(obj);
 }
 
+void MacroAssembler::store_check(Register obj) {
+  // Does a store check for the oop in register obj. The content of
+  // register obj is destroyed afterwards.
 
-// split the store check operation so that other instructions can be scheduled inbetween
-void MacroAssembler::store_check_part_1(Register obj) {
   BarrierSet* bs = Universe::heap()->barrier_set();
   assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
-  shrptr(obj, CardTableModRefBS::card_shift);
-}
 
-void MacroAssembler::store_check_part_2(Register obj) {
-  BarrierSet* bs = Universe::heap()->barrier_set();
-  assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
   CardTableModRefBS* ct = barrier_set_cast<CardTableModRefBS>(bs);
   assert(sizeof(*ct->byte_map_base) == sizeof(jbyte), "adjust this code");
 
+  shrptr(obj, CardTableModRefBS::card_shift);
+
+  Address card_addr;
+
   // The calculation for byte_map_base is as follows:
   // byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
   // So this essentially converts an address to a displacement and it will
@@ -4329,8 +4322,7 @@
   // large for a 32bit displacement.
   intptr_t disp = (intptr_t) ct->byte_map_base;
   if (is_simm32(disp)) {
-    Address cardtable(noreg, obj, Address::times_1, disp);
-    movb(cardtable, 0);
+    card_addr = Address(noreg, obj, Address::times_1, disp);
   } else {
     // By doing it as an ExternalAddress 'disp' could be converted to a rip-relative
     // displacement and done in a single instruction given favorable mapping and a
@@ -4338,7 +4330,18 @@
     // entry and that entry is not properly handled by the relocation code.
     AddressLiteral cardtable((address)ct->byte_map_base, relocInfo::none);
     Address index(noreg, obj, Address::times_1);
-    movb(as_Address(ArrayAddress(cardtable, index)), 0);
+    card_addr = as_Address(ArrayAddress(cardtable, index));
+  }
+
+  int dirty = CardTableModRefBS::dirty_card_val();
+  if (UseCondCardMark) {
+    Label L_already_dirty;
+    cmpb(card_addr, dirty);
+    jcc(Assembler::equal, L_already_dirty);
+    movb(card_addr, dirty);
+    bind(L_already_dirty);
+  } else {
+    movb(card_addr, dirty);
   }
 }
 
--- old/src/cpu/x86/vm/macroAssembler_x86.hpp	2015-05-06 19:23:48.977496103 +0300
+++ new/src/cpu/x86/vm/macroAssembler_x86.hpp	2015-05-06 19:23:48.925499565 +0300
@@ -315,10 +315,6 @@
 
 #endif // INCLUDE_ALL_GCS
 
-  // split store_check(Register obj) to enhance instruction interleaving
-  void store_check_part_1(Register obj);
-  void store_check_part_2(Register obj);
-
   // C 'boolean' to Java boolean: x == 0 ? 0 : 1
   void c2bool(Register x);
 
--- /dev/null	2015-05-01 17:48:48.457547995 +0300
+++ new/test/gc/CondCardMark/Basic.java	2015-05-06 19:23:49.117486763 +0300
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2014, 2015, 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.
+ */
+
+/**
+ * @test
+ * @bug 8076987
+ * @bug 8078438
+ * @summary Verify UseCondCardMark works
+ * @library /testlibrary /../../test/lib
+ * @build Basic
+ * @run main/othervm -Xint Basic
+ * @run main/othervm -Xint -XX:+UseCondCardMark Basic
+ * @run main/othervm -XX:TieredStopAtLevel=1 Basic
+ * @run main/othervm -XX:TieredStopAtLevel=1 -XX:+UseCondCardMark Basic
+ * @run main/othervm -XX:TieredStopAtLevel=4 Basic
+ * @run main/othervm -XX:TieredStopAtLevel=4 -XX:+UseCondCardMark Basic
+ * @run main/othervm -XX:-TieredCompilation Basic
+ * @run main/othervm -XX:-TieredCompilation -XX:+UseCondCardMark Basic
+*/
+public class Basic {
+
+    static volatile MyObject sink;
+
+    public static void main(String args[]) {
+        final int COUNT = 10000000;
+        for (int c = 0; c < COUNT; c++) {
+             MyObject o = new MyObject();
+             o.x = c;
+             doStore(o);
+        }
+
+        if (sink.x != COUNT-1) {
+             throw new IllegalStateException("Failed");
+        }
+    }
+
+    public static void doStore(MyObject o) {
+        sink = o;
+    }
+
+    static class MyObject {
+        int x;
+    }
+
+}