1 
   2 /*
   3  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "asm/macroAssembler.inline.hpp"
  28 #include "gc/shared/barrierSet.hpp"
  29 #include "gc/shared/cardTable.hpp"
  30 #include "gc/shared/cardTableModRefBS.hpp"
  31 #include "gc/shared/cardTableModRefBSCodeGen.hpp"
  32 #include "gc/shared/collectedHeap.hpp"
  33 #include "interpreter/interp_masm.hpp"
  34 
  35 #define __ masm->
  36 
  37 #ifdef PRODUCT
  38 #define BLOCK_COMMENT(str) /* nothing */
  39 #else
  40 #define BLOCK_COMMENT(str) __ block_comment(str)
  41 #endif
  42 
  43 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")
  44 
  45 void CardTableModRefBSCodeGen::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators, Register addr, Register count, Register tmp) {
  46   CardTableModRefBS* ct = barrier_set_cast<CardTableModRefBS>(Universe::heap()->barrier_set());
  47   assert(sizeof(*ct->card_table()->byte_map_base()) == sizeof(jbyte), "adjust this code");
  48   assert_different_registers(addr, count, tmp);
  49 
  50   Label L_loop;
  51 
  52   __ sll_ptr(count, LogBytesPerHeapOop, count);
  53   __ sub(count, BytesPerHeapOop, count);
  54   __ add(count, addr, count);
  55   // Use two shifts to clear out those low order two bits! (Cannot opt. into 1.)
  56   __ srl_ptr(addr, CardTable::card_shift, addr);
  57   __ srl_ptr(count, CardTable::card_shift, count);
  58   __ sub(count, addr, count);
  59   AddressLiteral rs((address)ct->card_table()->byte_map_base());
  60   __ set(rs, tmp);
  61   __ BIND(L_loop);
  62   __ stb(G0, tmp, addr);
  63   __ subcc(count, 1, count);
  64   __ brx(Assembler::greaterEqual, false, Assembler::pt, L_loop);
  65   __ delayed()->add(addr, 1, addr);
  66 }
  67 
  68 void CardTableModRefBSCodeGen::card_table_write(MacroAssembler* masm,
  69                                                 jbyte* byte_map_base,
  70                                                 Register tmp, Register obj) {
  71 #ifdef _LP64
  72   __ srlx(obj, CardTable::card_shift, obj);
  73 #else
  74   __ srl(obj, CardTable::card_shift, obj);
  75 #endif
  76   assert(tmp != obj, "need separate temp reg");
  77   __ set((address) byte_map_base, tmp);
  78   __ stb(G0, tmp, obj);
  79 }
  80 
  81 void CardTableModRefBSCodeGen::card_write_barrier_post(MacroAssembler* masm, Register store_addr, Register new_val, Register tmp) {
  82   // If we're writing constant NULL, we can skip the write barrier.
  83   if (new_val == G0) return;
  84   CardTableModRefBS* bs =
  85     barrier_set_cast<CardTableModRefBS>(Universe::heap()->barrier_set());
  86   card_table_write(masm, bs->card_table()->byte_map_base(), tmp, store_addr);
  87 }
  88 
  89 void CardTableModRefBSCodeGen::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
  90                                             Register base, Register index, int offset, Register val, Register tmp) {
  91   bool on_array = (decorators & ACCESS_ON_ARRAY) != 0;
  92   bool on_anonymous = (decorators & ACCESS_ON_ANONYMOUS) != 0;
  93   bool precise = on_array || on_anonymous;
  94   BarrierSetCodeGen::store_at(masm, decorators, type, base, index, offset, val, tmp);
  95   // No need for post barrier if storing NULL
  96   if (val != G0) {
  97     if (precise) {
  98       if (index == noreg) {
  99         __ add(base, offset, base);
 100       } else {
 101         __ add(base, index, base);
 102       }
 103     }
 104     card_write_barrier_post(masm, base, val, tmp);
 105   }
 106 }