3a2343d9e6
Reviewed-by: stefank, eosterlund
258 lines
8.2 KiB
C++
258 lines
8.2 KiB
C++
/*
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* Copyright (c) 2015, 2019, 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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#include "precompiled.hpp"
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#include "gc/z/zBarrier.inline.hpp"
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#include "gc/z/zHeap.inline.hpp"
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#include "gc/z/zOop.inline.hpp"
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#include "gc/z/zOopClosures.inline.hpp"
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#include "memory/iterator.inline.hpp"
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#include "oops/oop.inline.hpp"
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#include "runtime/safepoint.hpp"
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#include "utilities/debug.hpp"
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bool ZBarrier::during_mark() {
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return ZGlobalPhase == ZPhaseMark;
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}
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bool ZBarrier::during_relocate() {
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return ZGlobalPhase == ZPhaseRelocate;
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}
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template <bool finalizable>
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bool ZBarrier::should_mark_through(uintptr_t addr) {
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// Finalizable marked oops can still exists on the heap after marking
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// has completed, in which case we just want to convert this into a
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// good oop and not push it on the mark stack.
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if (!during_mark()) {
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assert(ZAddress::is_marked(addr), "Should be marked");
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assert(ZAddress::is_finalizable(addr), "Should be finalizable");
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return false;
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}
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// During marking, we mark through already marked oops to avoid having
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// some large part of the object graph hidden behind a pushed, but not
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// yet flushed, entry on a mutator mark stack. Always marking through
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// allows the GC workers to proceed through the object graph even if a
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// mutator touched an oop first, which in turn will reduce the risk of
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// having to flush mark stacks multiple times to terminate marking.
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//
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// However, when doing finalizable marking we don't always want to mark
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// through. First, marking through an already strongly marked oop would
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// be wasteful, since we will then proceed to do finalizable marking on
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// an object which is, or will be, marked strongly. Second, marking
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// through an already finalizable marked oop would also be wasteful,
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// since such oops can never end up on a mutator mark stack and can
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// therefore not hide some part of the object graph from GC workers.
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if (finalizable) {
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return !ZAddress::is_marked(addr);
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}
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// Mark through
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return true;
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}
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template <bool finalizable, bool publish>
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uintptr_t ZBarrier::mark(uintptr_t addr) {
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uintptr_t good_addr;
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if (ZAddress::is_marked(addr)) {
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// Already marked, but try to mark though anyway
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good_addr = ZAddress::good(addr);
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} else if (ZAddress::is_remapped(addr)) {
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// Already remapped, but also needs to be marked
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good_addr = ZAddress::good(addr);
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} else {
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// Needs to be both remapped and marked
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good_addr = remap(addr);
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}
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// Mark
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if (should_mark_through<finalizable>(addr)) {
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ZHeap::heap()->mark_object<finalizable, publish>(good_addr);
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}
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return good_addr;
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}
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uintptr_t ZBarrier::remap(uintptr_t addr) {
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assert(!ZAddress::is_good(addr), "Should not be good");
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assert(!ZAddress::is_weak_good(addr), "Should not be weak good");
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return ZHeap::heap()->remap_object(addr);
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}
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uintptr_t ZBarrier::relocate(uintptr_t addr) {
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assert(!ZAddress::is_good(addr), "Should not be good");
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assert(!ZAddress::is_weak_good(addr), "Should not be weak good");
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return ZHeap::heap()->relocate_object(addr);
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}
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uintptr_t ZBarrier::relocate_or_mark(uintptr_t addr) {
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return during_relocate() ? relocate(addr) : mark<Strong, Publish>(addr);
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}
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uintptr_t ZBarrier::relocate_or_remap(uintptr_t addr) {
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return during_relocate() ? relocate(addr) : remap(addr);
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}
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//
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// Load barrier
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//
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uintptr_t ZBarrier::load_barrier_on_oop_slow_path(uintptr_t addr) {
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return relocate_or_mark(addr);
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}
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void ZBarrier::load_barrier_on_oop_fields(oop o) {
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assert(ZAddress::is_good(ZOop::to_address(o)), "Should be good");
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ZLoadBarrierOopClosure cl;
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o->oop_iterate(&cl);
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}
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//
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// Weak load barrier
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//
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uintptr_t ZBarrier::weak_load_barrier_on_oop_slow_path(uintptr_t addr) {
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return ZAddress::is_weak_good(addr) ? ZAddress::good(addr) : relocate_or_remap(addr);
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}
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uintptr_t ZBarrier::weak_load_barrier_on_weak_oop_slow_path(uintptr_t addr) {
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const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
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if (ZHeap::heap()->is_object_strongly_live(good_addr)) {
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return good_addr;
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}
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// Not strongly live
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return 0;
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}
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uintptr_t ZBarrier::weak_load_barrier_on_phantom_oop_slow_path(uintptr_t addr) {
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const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
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if (ZHeap::heap()->is_object_live(good_addr)) {
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return good_addr;
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}
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// Not live
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return 0;
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}
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//
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// Keep alive barrier
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//
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uintptr_t ZBarrier::keep_alive_barrier_on_weak_oop_slow_path(uintptr_t addr) {
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const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
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assert(ZHeap::heap()->is_object_strongly_live(good_addr), "Should be live");
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return good_addr;
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}
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uintptr_t ZBarrier::keep_alive_barrier_on_phantom_oop_slow_path(uintptr_t addr) {
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const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
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assert(ZHeap::heap()->is_object_live(good_addr), "Should be live");
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return good_addr;
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}
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//
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// Mark barrier
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//
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uintptr_t ZBarrier::mark_barrier_on_oop_slow_path(uintptr_t addr) {
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return mark<Strong, Overflow>(addr);
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}
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uintptr_t ZBarrier::mark_barrier_on_finalizable_oop_slow_path(uintptr_t addr) {
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const uintptr_t good_addr = mark<Finalizable, Overflow>(addr);
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if (ZAddress::is_good(addr)) {
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// If the oop was already strongly marked/good, then we do
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// not want to downgrade it to finalizable marked/good.
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return good_addr;
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}
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// Make the oop finalizable marked/good, instead of normal marked/good.
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// This is needed because an object might first becomes finalizable
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// marked by the GC, and then loaded by a mutator thread. In this case,
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// the mutator thread must be able to tell that the object needs to be
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// strongly marked. The finalizable bit in the oop exists to make sure
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// that a load of a finalizable marked oop will fall into the barrier
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// slow path so that we can mark the object as strongly reachable.
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return ZAddress::finalizable_good(good_addr);
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}
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uintptr_t ZBarrier::mark_barrier_on_root_oop_slow_path(uintptr_t addr) {
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assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
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assert(during_mark(), "Invalid phase");
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// Mark
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return mark<Strong, Publish>(addr);
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}
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//
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// Relocate barrier
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//
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uintptr_t ZBarrier::relocate_barrier_on_root_oop_slow_path(uintptr_t addr) {
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assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
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assert(during_relocate(), "Invalid phase");
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// Relocate
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return relocate(addr);
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}
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//
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// Narrow oop variants, never used.
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//
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oop ZBarrier::load_barrier_on_oop_field(volatile narrowOop* p) {
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ShouldNotReachHere();
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return NULL;
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}
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oop ZBarrier::load_barrier_on_oop_field_preloaded(volatile narrowOop* p, oop o) {
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ShouldNotReachHere();
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return NULL;
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}
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void ZBarrier::load_barrier_on_oop_array(volatile narrowOop* p, size_t length) {
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ShouldNotReachHere();
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}
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oop ZBarrier::load_barrier_on_weak_oop_field_preloaded(volatile narrowOop* p, oop o) {
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ShouldNotReachHere();
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return NULL;
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}
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oop ZBarrier::load_barrier_on_phantom_oop_field_preloaded(volatile narrowOop* p, oop o) {
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ShouldNotReachHere();
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return NULL;
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}
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oop ZBarrier::weak_load_barrier_on_oop_field_preloaded(volatile narrowOop* p, oop o) {
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ShouldNotReachHere();
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return NULL;
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}
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oop ZBarrier::weak_load_barrier_on_weak_oop_field_preloaded(volatile narrowOop* p, oop o) {
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ShouldNotReachHere();
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return NULL;
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}
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oop ZBarrier::weak_load_barrier_on_phantom_oop_field_preloaded(volatile narrowOop* p, oop o) {
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ShouldNotReachHere();
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return NULL;
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}
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