1 /*
  2  * Copyright (c) 2018, 2025, 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 "asm/macroAssembler.inline.hpp"
 26 #include "code/aotCodeCache.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/gc_globals.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 #define TIMES_OOP (UseCompressedOops ? Address::times_4 : Address::times_8)
 44 
 45 void CardTableBarrierSetAssembler::gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
 46                                                                     Register addr, Register count, Register tmp) {
 47   BarrierSet *bs = BarrierSet::barrier_set();
 48   CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(bs);
 49   CardTable* ct = ctbs->card_table();
 50   intptr_t byte_map_base = (intptr_t) ct->byte_map_base();
 51   SHENANDOAHGC_ONLY(assert(!UseShenandoahGC, "Shenandoah byte_map_base is not constant.");)
 52 
 53   Label L_loop, L_done;
 54   const Register end = count;
 55   assert_different_registers(addr, end);
 56 
 57   __ testl(count, count);
 58   __ jcc(Assembler::zero, L_done); // zero count - nothing to do
 59 
 60 
 61   __ leaq(end, Address(addr, count, TIMES_OOP, 0));  // end == addr+count*oop_size
 62   __ subptr(end, BytesPerHeapOop); // end - 1 to make inclusive
 63   __ shrptr(addr, CardTable::card_shift());
 64   __ shrptr(end, CardTable::card_shift());
 65   __ subptr(end, addr); // end --> cards count
 66 
 67 #if INCLUDE_CDS
 68   if (AOTCodeCache::is_on_for_dump()) {
 69     __ movptr(tmp, ExternalAddress(AOTRuntimeConstants::card_table_address()));
 70   } else
 71 #endif
 72   {
 73     __ mov64(tmp, byte_map_base);
 74   }
 75   __ addptr(addr, tmp);
 76 __ BIND(L_loop);
 77   __ movb(Address(addr, count, Address::times_1), 0);
 78   __ decrement(count);
 79   __ jcc(Assembler::greaterEqual, L_loop);
 80 
 81 __ BIND(L_done);
 82 }
 83 
 84 void CardTableBarrierSetAssembler::store_check(MacroAssembler* masm, Register obj, Address dst, Register rscratch) {
 85   // Does a store check for the oop in register obj. The content of
 86   // register obj is destroyed afterwards.
 87   BarrierSet* bs = BarrierSet::barrier_set();
 88 
 89   CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(bs);
 90   CardTable* ct = ctbs->card_table();
 91 
 92   __ shrptr(obj, CardTable::card_shift());
 93 
 94   Address card_addr;
 95   precond(rscratch != noreg);
 96 
 97   // The calculation for byte_map_base is as follows:
 98   // byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
 99   // So this essentially converts an address to a displacement and it will
100   // never need to be relocated. On 64bit however the value may be too
101   // large for a 32bit displacement.
102   intptr_t byte_map_base = (intptr_t)ct->byte_map_base();
103 #if INCLUDE_CDS
104   if (AOTCodeCache::is_on_for_dump()) {
105     __ movptr(rscratch, ExternalAddress(AOTRuntimeConstants::card_table_address()));
106     card_addr = Address(rscratch, obj, Address::times_1, 0);
107   } else
108 #endif
109   if (__ is_simm32(byte_map_base)) {
110     card_addr = Address(noreg, obj, Address::times_1, byte_map_base);
111   } else {
112     // By doing it as an ExternalAddress 'byte_map_base' could be converted to a rip-relative
113     // displacement and done in a single instruction given favorable mapping and a
114     // smarter version of as_Address. However, 'ExternalAddress' generates a relocation
115     // entry and that entry is not properly handled by the relocation code.
116     AddressLiteral cardtable((address)byte_map_base, relocInfo::none);
117     Address index(noreg, obj, Address::times_1);
118     card_addr = __ as_Address(ArrayAddress(cardtable, index), rscratch);
119   }
120 
121   int dirty = CardTable::dirty_card_val();
122   if (UseCondCardMark) {
123     Label L_already_dirty;
124     __ cmpb(card_addr, dirty);
125     __ jccb(Assembler::equal, L_already_dirty);
126     __ movb(card_addr, dirty);
127     __ bind(L_already_dirty);
128   } else {
129     __ movb(card_addr, dirty);
130   }
131 }
132 
133 void CardTableBarrierSetAssembler::oop_store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
134                                                 Address dst, Register val, Register tmp1, Register tmp2, Register tmp3) {
135   bool in_heap = (decorators & IN_HEAP) != 0;
136 
137   bool is_array = (decorators & IS_ARRAY) != 0;
138   bool on_anonymous = (decorators & ON_UNKNOWN_OOP_REF) != 0;
139   bool precise = is_array || on_anonymous;
140 
141   bool needs_post_barrier = val != noreg && in_heap;
142 
143   BarrierSetAssembler::store_at(masm, decorators, type, dst, val, noreg, noreg, noreg);
144   if (needs_post_barrier) {
145     // flatten object address if needed
146     if (!precise || (dst.index() == noreg && dst.disp() == 0)) {
147       store_check(masm, dst.base(), dst, tmp2);
148     } else {
149       __ lea(tmp1, dst);
150       store_check(masm, tmp1, dst, tmp2);
151     }
152   }
153 }