1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/cardTableModRefBSCodeGen.hpp"
  27 
  28 #define __ masm->
  29 
  30 void CardTableModRefBSCodeGen::store_check(MacroAssembler* masm, Register obj, Address dst) {
  31   // Does a store check for the oop in register obj. The content of
  32   // register obj is destroyed afterwards.
  33 
  34   BarrierSet* bs = Universe::heap()->barrier_set();
  35   assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
  36 
  37   CardTableModRefBS* ctbs = barrier_set_cast<CardTableModRefBS>(bs);
  38   CardTable* ct = ctbs->card_table();
  39   assert(sizeof(*ct->byte_map_base()) == sizeof(jbyte), "adjust this code");
  40 
  41   __ lsr(obj, obj, CardTable::card_shift);
  42 
  43   assert(CardTable::dirty_card_val() == 0, "must be");
  44 
  45   __ load_byte_map_base(rscratch1);
  46 
  47   if (UseCondCardMark) {
  48     Label L_already_dirty;
  49     __ membar(Assembler::StoreLoad);
  50     __ ldrb(rscratch2,  Address(obj, rscratch1));
  51     __ cbz(rscratch2, L_already_dirty);
  52     __ strb(zr, Address(obj, rscratch1));
  53     __ bind(L_already_dirty);
  54   } else {
  55     if (UseConcMarkSweepGC && CMSPrecleaningEnabled) {
  56       __ membar(Assembler::StoreStore);
  57     }
  58     __ strb(zr, Address(obj, rscratch1));
  59   }
  60 }
  61 
  62 void CardTableModRefBSCodeGen::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
  63                                                                 Register start, Register end, Register scratch, RegSet saved_regs) {
  64 
  65   BarrierSet* bs = Universe::heap()->barrier_set();
  66   CardTableModRefBS* ctbs = barrier_set_cast<CardTableModRefBS>(bs);
  67   CardTable* ct = ctbs->card_table();
  68   assert(sizeof(*ct->byte_map_base()) == sizeof(jbyte), "adjust this code");
  69 
  70   Label L_loop;
  71 
  72   __ lsr(start, start, CardTable::card_shift);
  73   __ lsr(end, end, CardTable::card_shift);
  74   __ sub(end, end, start); // number of bytes to copy
  75 
  76   const Register count = end; // 'end' register contains bytes count now
  77   __ load_byte_map_base(scratch);
  78   __ add(start, start, scratch);
  79   if (UseConcMarkSweepGC) {
  80     __ membar(__ StoreStore);
  81   }
  82   __ bind(L_loop);
  83   __ strb(zr, Address(start, count));
  84   __ subs(count, count, 1);
  85   __ br(Assembler::GE, L_loop);
  86 }
  87 
  88 void CardTableModRefBSCodeGen::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
  89                                             Address dst, Register val, Register tmp1, Register tmp2) {
  90 
  91   bool on_array = (decorators & ACCESS_IN_HEAP_ARRAY) != 0;
  92   bool on_anonymous = (decorators & ACCESS_ON_UNKNOWN_OOP_REF) != 0;
  93   bool precise = on_array || on_anonymous;
  94   if (val == noreg) {
  95     __ store_heap_oop_null(dst);
  96   } else {
  97     __ store_heap_oop(dst, val);
  98     // flatten object address if needed
  99     if (!precise || (dst.index() == noreg && dst.offset() == 0)) {
 100       store_check(masm, dst.base(), dst);
 101     } else {
 102       __ lea(r3, dst);
 103       store_check(masm, r3, dst);
 104     }
 105   }
 106 }
 107