1 
   2 /*
   3  * Copyright (c) 2018, 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/cardTableBarrierSet.hpp"
  31 #include "gc/shared/cardTableBarrierSetAssembler.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 CardTableBarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
  46                                                                     Register addr, Register count, Register tmp) {
  47   CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(Universe::heap()->barrier_set());
  48   CardTable* ct = ctbs->card_table();
  49   assert(sizeof(*ct->byte_map_base()) == sizeof(jbyte), "adjust this code");
  50   assert_different_registers(addr, count, tmp);
  51 
  52   Label L_loop, L_done;
  53 
  54   __ cmp_and_br_short(count, 0, Assembler::equal, Assembler::pt, L_done); // zero count - nothing to do
  55 
  56   __ sll_ptr(count, LogBytesPerHeapOop, count);
  57   __ sub(count, BytesPerHeapOop, count);
  58   __ add(count, addr, count);
  59   // Use two shifts to clear out those low order two bits! (Cannot opt. into 1.)
  60   __ srl_ptr(addr, CardTable::card_shift, addr);
  61   __ srl_ptr(count, CardTable::card_shift, count);
  62   __ sub(count, addr, count);
  63   AddressLiteral rs(ct->byte_map_base());
  64   __ set(rs, tmp);
  65   __ BIND(L_loop);
  66   __ stb(G0, tmp, addr);
  67   __ subcc(count, 1, count);
  68   __ brx(Assembler::greaterEqual, false, Assembler::pt, L_loop);
  69   __ delayed()->add(addr, 1, addr);
  70 
  71   __ BIND(L_done);
  72 }
  73 
  74 void CardTableBarrierSetAssembler::card_table_write(MacroAssembler* masm,
  75                                                     jbyte* byte_map_base,
  76                                                     Register tmp, Register obj) {
  77   __ srlx(obj, CardTable::card_shift, obj);
  78   assert(tmp != obj, "need separate temp reg");
  79   __ set((address) byte_map_base, tmp);
  80   __ stb(G0, tmp, obj);
  81 }
  82 
  83 void CardTableBarrierSetAssembler::card_write_barrier_post(MacroAssembler* masm, Register store_addr, Register new_val, Register tmp) {
  84   // If we're writing constant NULL, we can skip the write barrier.
  85   if (new_val == G0) return;
  86   CardTableBarrierSet* bs = barrier_set_cast<CardTableBarrierSet>(Universe::heap()->barrier_set());
  87   card_table_write(masm, bs->card_table()->byte_map_base(), tmp, store_addr);
  88 }
  89 
  90 void CardTableBarrierSetAssembler::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
  91                                                 Register val, Address dst, Register tmp) {
  92   bool in_heap = (decorators & IN_HEAP) != 0;
  93 
  94   bool on_array = (decorators & IN_HEAP_ARRAY) != 0;
  95   bool on_anonymous = (decorators & ON_UNKNOWN_OOP_REF) != 0;
  96   bool precise = on_array || on_anonymous;
  97 
  98   // No need for post barrier if storing NULL
  99   bool needs_post_barrier = val != G0 && in_heap;
 100 
 101   BarrierSetAssembler::store_at(masm, decorators, type, val, dst, tmp);
 102   if (needs_post_barrier) {
 103     Register base = dst.base();
 104     if (precise) {
 105       if (!dst.has_index()) {
 106         __ add(base, dst.disp(), base);
 107       } else {
 108         assert(!dst.has_disp(), "not supported yet");
 109         __ add(base, dst.index(), base);
 110       }
 111     }
 112     card_write_barrier_post(masm, base, val, tmp);
 113   }
 114 }