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 "interpreter/interp_masm.hpp"
  32 
  33 #define __ masm->
  34 
  35 #ifdef PRODUCT
  36 #define BLOCK_COMMENT(str) /* nothing */
  37 #else
  38 #define BLOCK_COMMENT(str) __ block_comment(str)
  39 #endif
  40 
  41 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")
  42 
  43 void CardTableBarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
  44                                                                     Register addr, Register count, Register tmp) {
  45   CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(BarrierSet::barrier_set());
  46   CardTable* ct = ctbs->card_table();
  47   assert_different_registers(addr, count, tmp);
  48 
  49   Label L_loop, L_done;
  50 
  51   __ cmp_and_br_short(count, 0, Assembler::equal, Assembler::pt, L_done); // zero count - nothing to do
  52 
  53   __ sll_ptr(count, LogBytesPerHeapOop, count);
  54   __ sub(count, BytesPerHeapOop, count);
  55   __ add(count, addr, count);
  56   // Use two shifts to clear out those low order two bits! (Cannot opt. into 1.)
  57   __ srl_ptr(addr, CardTable::card_shift, addr);
  58   __ srl_ptr(count, CardTable::card_shift, count);
  59   __ sub(count, addr, count);
  60   AddressLiteral rs(ct->byte_map_base());
  61   __ set(rs, tmp);
  62   __ BIND(L_loop);
  63   __ stb(G0, tmp, addr);
  64   __ subcc(count, 1, count);
  65   __ brx(Assembler::greaterEqual, false, Assembler::pt, L_loop);
  66   __ delayed()->add(addr, 1, addr);
  67 
  68   __ BIND(L_done);
  69 }
  70 
  71 void CardTableBarrierSetAssembler::card_table_write(MacroAssembler* masm,
  72                                                     CardTable::CardValue* byte_map_base,
  73                                                     Register tmp, Register obj) {
  74   __ srlx(obj, CardTable::card_shift, obj);
  75   assert(tmp != obj, "need separate temp reg");
  76   __ set((address) byte_map_base, tmp);
  77   __ stb(G0, tmp, obj);
  78 }
  79 
  80 void CardTableBarrierSetAssembler::card_write_barrier_post(MacroAssembler* masm, Register store_addr, Register new_val, Register tmp) {
  81   // If we're writing constant NULL, we can skip the write barrier.
  82   if (new_val == G0) return;
  83   CardTableBarrierSet* bs = barrier_set_cast<CardTableBarrierSet>(BarrierSet::barrier_set());
  84   card_table_write(masm, bs->card_table()->byte_map_base(), tmp, store_addr);
  85 }
  86 
  87 void CardTableBarrierSetAssembler::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
  88                                                 Register val, Address dst, Register tmp) {
  89   bool in_heap = (decorators & IN_HEAP) != 0;
  90 
  91   bool is_array = (decorators & IS_ARRAY) != 0;
  92   bool on_anonymous = (decorators & ON_UNKNOWN_OOP_REF) != 0;
  93   bool precise = is_array || on_anonymous;
  94 
  95   // No need for post barrier if storing NULL
  96   bool needs_post_barrier = val != G0 && in_heap;
  97 
  98   BarrierSetAssembler::store_at(masm, decorators, type, val, dst, tmp);
  99   if (needs_post_barrier) {
 100     Register base = dst.base();
 101     if (precise) {
 102       if (!dst.has_index()) {
 103         __ add(base, dst.disp(), base);
 104       } else {
 105         assert(!dst.has_disp(), "not supported yet");
 106         __ add(base, dst.index(), base);
 107       }
 108     }
 109     card_write_barrier_post(masm, base, val, tmp);
 110   }
 111 }