1 /*
   2  * Copyright (c) 2018, 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 "asm/macroAssembler.inline.hpp"
  27 #include "gc/shared/barrierSet.hpp"
  28 #include "gc/shared/cardTable.hpp"
  29 #include "gc/shared/cardTableBarrierSet.hpp"
  30 #include "gc/shared/cardTableBarrierSetAssembler.hpp"
  31 #include "gc/shared/collectedHeap.hpp"
  32 #include "runtime/globals.hpp"
  33 
  34 #define __ masm->
  35 
  36 #ifdef PRODUCT
  37 #define BLOCK_COMMENT(str) /* nothing */
  38 #else
  39 #define BLOCK_COMMENT(str) __ block_comment(str)
  40 #endif
  41 
  42 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")
  43 
  44 void CardTableBarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
  45                                                                     Register addr, Register count, Register tmp) {
  46   BLOCK_COMMENT("CardTablePostBarrier");
  47   BarrierSet* bs = BarrierSet::barrier_set();
  48   CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(bs);
  49   CardTable* ct = ctbs->card_table();
  50   assert(sizeof(*ct->byte_map_base()) == sizeof(jbyte), "adjust this code");
  51 
  52   Label L_cardtable_loop, L_done;
  53 
  54   __ cbz_32(count, L_done); // zero count - nothing to do
  55 
  56   __ add_ptr_scaled_int32(count, addr, count, LogBytesPerHeapOop);
  57   __ sub(count, count, BytesPerHeapOop);                            // last addr
  58 
  59   __ logical_shift_right(addr, addr, CardTable::card_shift);
  60   __ logical_shift_right(count, count, CardTable::card_shift);
  61   __ sub(count, count, addr); // nb of cards
  62 
  63   // warning: Rthread has not been preserved
  64   __ mov_address(tmp, (address) ct->byte_map_base(), symbolic_Relocation::card_table_reference);
  65   __ add(addr,tmp, addr);
  66 
  67   Register zero = __ zero_register(tmp);
  68 
  69   __ BIND(L_cardtable_loop);
  70   __ strb(zero, Address(addr, 1, post_indexed));
  71   __ subs(count, count, 1);
  72   __ b(L_cardtable_loop, ge);
  73   __ BIND(L_done);
  74 }