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/*
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* Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "ci/ciUtilities.hpp"
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#include "gc/shared/cardTable.hpp"
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#include "gc/shared/cardTableBarrierSet.hpp"
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#include "gc/shared/c2/cardTableBarrierSetC2.hpp"
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#include "opto/arraycopynode.hpp"
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#include "opto/graphKit.hpp"
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#include "opto/idealKit.hpp"
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#include "opto/macro.hpp"
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#include "utilities/macros.hpp"
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#define __ ideal.
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Node* CardTableBarrierSetC2::byte_map_base_node(GraphKit* kit) const {
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// Get base of card map
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jbyte* card_table_base = ci_card_table_address();
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if (card_table_base != NULL) {
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return kit->makecon(TypeRawPtr::make((address)card_table_base));
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} else {
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return kit->null();
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}
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}
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// vanilla/CMS post barrier
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// Insert a write-barrier store. This is to let generational GC work; we have
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// to flag all oop-stores before the next GC point.
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void CardTableBarrierSetC2::post_barrier(GraphKit* kit,
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Node* ctl,
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Node* oop_store,
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Node* obj,
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Node* adr,
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uint adr_idx,
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Node* val,
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BasicType bt,
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bool use_precise) const {
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CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(BarrierSet::barrier_set());
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CardTable* ct = ctbs->card_table();
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// No store check needed if we're storing a NULL or an old object
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// (latter case is probably a string constant). The concurrent
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// mark sweep garbage collector, however, needs to have all nonNull
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// oop updates flagged via card-marks.
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if (val != NULL && val->is_Con()) {
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// must be either an oop or NULL
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const Type* t = val->bottom_type();
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if (t == TypePtr::NULL_PTR || t == Type::TOP)
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// stores of null never (?) need barriers
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return;
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}
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if (use_ReduceInitialCardMarks()
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&& obj == kit->just_allocated_object(kit->control())) {
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// We can skip marks on a freshly-allocated object in Eden.
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// Keep this code in sync with new_deferred_store_barrier() in runtime.cpp.
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// That routine informs GC to take appropriate compensating steps,
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// upon a slow-path allocation, so as to make this card-mark
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// elision safe.
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return;
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}
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if (!use_precise) {
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// All card marks for a (non-array) instance are in one place:
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adr = obj;
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}
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// (Else it's an array (or unknown), and we want more precise card marks.)
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assert(adr != NULL, "");
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IdealKit ideal(kit, true);
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// Convert the pointer to an int prior to doing math on it
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Node* cast = __ CastPX(__ ctrl(), adr);
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// Divide by card size
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Node* card_offset = __ URShiftX( cast, __ ConI(CardTable::card_shift) );
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// Combine card table base and card offset
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Node* card_adr = __ AddP(__ top(), byte_map_base_node(kit), card_offset );
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// Get the alias_index for raw card-mark memory
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int adr_type = Compile::AliasIdxRaw;
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Node* zero = __ ConI(0); // Dirty card value
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if (UseCondCardMark) {
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if (ct->scanned_concurrently()) {
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kit->insert_mem_bar(Op_MemBarVolatile, oop_store);
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__ sync_kit(kit);
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}
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// The classic GC reference write barrier is typically implemented
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// as a store into the global card mark table. Unfortunately
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// unconditional stores can result in false sharing and excessive
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// coherence traffic as well as false transactional aborts.
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// UseCondCardMark enables MP "polite" conditional card mark
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// stores. In theory we could relax the load from ctrl() to
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// no_ctrl, but that doesn't buy much latitude.
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Node* card_val = __ load( __ ctrl(), card_adr, TypeInt::BYTE, T_BYTE, adr_type);
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__ if_then(card_val, BoolTest::ne, zero);
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}
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// Smash zero into card
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if(!ct->scanned_concurrently()) {
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__ store(__ ctrl(), card_adr, zero, T_BYTE, adr_type, MemNode::unordered);
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} else {
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// Specialized path for CM store barrier
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__ storeCM(__ ctrl(), card_adr, zero, oop_store, adr_idx, T_BYTE, adr_type);
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}
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if (UseCondCardMark) {
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__ end_if();
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}
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// Final sync IdealKit and GraphKit.
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kit->final_sync(ideal);
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}
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void CardTableBarrierSetC2::clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) const {
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BarrierSetC2::clone(kit, src, dst, size, is_array);
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const TypePtr* raw_adr_type = TypeRawPtr::BOTTOM;
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// If necessary, emit some card marks afterwards. (Non-arrays only.)
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bool card_mark = !is_array && !use_ReduceInitialCardMarks();
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if (card_mark) {
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assert(!is_array, "");
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// Put in store barrier for any and all oops we are sticking
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// into this object. (We could avoid this if we could prove
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// that the object type contains no oop fields at all.)
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Node* no_particular_value = NULL;
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Node* no_particular_field = NULL;
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int raw_adr_idx = Compile::AliasIdxRaw;
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post_barrier(kit, kit->control(),
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kit->memory(raw_adr_type),
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dst,
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no_particular_field,
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raw_adr_idx,
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no_particular_value,
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T_OBJECT,
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false);
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}
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}
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bool CardTableBarrierSetC2::use_ReduceInitialCardMarks() const {
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return ReduceInitialCardMarks;
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}
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bool CardTableBarrierSetC2::is_gc_barrier_node(Node* node) const {
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return ModRefBarrierSetC2::is_gc_barrier_node(node) || node->Opcode() == Op_StoreCM;
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}
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void CardTableBarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const {
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assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required");
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Node *shift = node->unique_out();
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Node *addp = shift->unique_out();
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for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) {
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Node *mem = addp->last_out(j);
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if (UseCondCardMark && mem->is_Load()) {
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assert(mem->Opcode() == Op_LoadB, "unexpected code shape");
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// The load is checking if the card has been written so
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// replace it with zero to fold the test.
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macro->replace_node(mem, macro->intcon(0));
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continue;
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}
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assert(mem->is_Store(), "store required");
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macro->replace_node(mem, mem->in(MemNode::Memory));
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}
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}
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bool CardTableBarrierSetC2::array_copy_requires_gc_barriers(BasicType type) const {
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return !use_ReduceInitialCardMarks();
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}
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