--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/z/zBarrier.cpp Tue Jun 12 17:40:28 2018 +0200
@@ -0,0 +1,270 @@
+/*
+ * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zBarrier.inline.hpp"
+#include "gc/z/zHeap.inline.hpp"
+#include "gc/z/zOop.inline.hpp"
+#include "gc/z/zOopClosures.inline.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/safepoint.hpp"
+#include "utilities/debug.hpp"
+
+bool ZBarrier::during_mark() {
+ return ZGlobalPhase == ZPhaseMark;
+}
+
+bool ZBarrier::during_relocate() {
+ return ZGlobalPhase == ZPhaseRelocate;
+}
+
+template <bool finalizable>
+bool ZBarrier::should_mark_through(uintptr_t addr) {
+ // Finalizable marked oops can still exists on the heap after marking
+ // has completed, in which case we just want to convert this into a
+ // good oop and not push it on the mark stack.
+ if (!during_mark()) {
+ assert(ZAddress::is_marked(addr), "Should be marked");
+ assert(ZAddress::is_finalizable(addr), "Should be finalizable");
+ return false;
+ }
+
+ // During marking, we mark through already marked oops to avoid having
+ // some large part of the object graph hidden behind a pushed, but not
+ // yet flushed, entry on a mutator mark stack. Always marking through
+ // allows the GC workers to proceed through the object graph even if a
+ // mutator touched an oop first, which in turn will reduce the risk of
+ // having to flush mark stacks multiple times to terminate marking.
+ //
+ // However, when doing finalizable marking we don't always want to mark
+ // through. First, marking through an already strongly marked oop would
+ // be wasteful, since we will then proceed to do finalizable marking on
+ // an object which is, or will be, marked strongly. Second, marking
+ // through an already finalizable marked oop would also be wasteful,
+ // since such oops can never end up on a mutator mark stack and can
+ // therefore not hide some part of the object graph from GC workers.
+ if (finalizable) {
+ return !ZAddress::is_marked(addr);
+ }
+
+ // Mark through
+ return true;
+}
+
+template <bool finalizable, bool publish>
+uintptr_t ZBarrier::mark(uintptr_t addr) {
+ uintptr_t good_addr;
+
+ if (ZAddress::is_marked(addr)) {
+ // Already marked, but try to mark though anyway
+ good_addr = ZAddress::good(addr);
+ } else if (ZAddress::is_remapped(addr)) {
+ // Already remapped, but also needs to be marked
+ good_addr = ZAddress::good(addr);
+ } else {
+ // Needs to be both remapped and marked
+ good_addr = remap(addr);
+ }
+
+ // Mark
+ if (should_mark_through<finalizable>(addr)) {
+ ZHeap::heap()->mark_object<finalizable, publish>(good_addr);
+ }
+
+ return good_addr;
+}
+
+uintptr_t ZBarrier::remap(uintptr_t addr) {
+ assert(!ZAddress::is_good(addr), "Should not be good");
+ assert(!ZAddress::is_weak_good(addr), "Should not be weak good");
+
+ if (ZHeap::heap()->is_relocating(addr)) {
+ // Forward
+ return ZHeap::heap()->forward_object(addr);
+ }
+
+ // Remap
+ return ZAddress::good(addr);
+}
+
+uintptr_t ZBarrier::relocate(uintptr_t addr) {
+ assert(!ZAddress::is_good(addr), "Should not be good");
+ assert(!ZAddress::is_weak_good(addr), "Should not be weak good");
+
+ if (ZHeap::heap()->is_relocating(addr)) {
+ // Relocate
+ return ZHeap::heap()->relocate_object(addr);
+ }
+
+ // Remap
+ return ZAddress::good(addr);
+}
+
+uintptr_t ZBarrier::relocate_or_mark(uintptr_t addr) {
+ return during_relocate() ? relocate(addr) : mark<Strong, Publish>(addr);
+}
+
+uintptr_t ZBarrier::relocate_or_remap(uintptr_t addr) {
+ return during_relocate() ? relocate(addr) : remap(addr);
+}
+
+//
+// Load barrier
+//
+uintptr_t ZBarrier::load_barrier_on_oop_slow_path(uintptr_t addr) {
+ return relocate_or_mark(addr);
+}
+
+void ZBarrier::load_barrier_on_oop_fields(oop o) {
+ assert(ZOop::is_good(o), "Should be good");
+ ZLoadBarrierOopClosure cl;
+ o->oop_iterate(&cl);
+}
+
+//
+// Weak load barrier
+//
+uintptr_t ZBarrier::weak_load_barrier_on_oop_slow_path(uintptr_t addr) {
+ return ZAddress::is_weak_good(addr) ? ZAddress::good(addr) : relocate_or_remap(addr);
+}
+
+uintptr_t ZBarrier::weak_load_barrier_on_weak_oop_slow_path(uintptr_t addr) {
+ const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
+ if (ZHeap::heap()->is_object_strongly_live(good_addr)) {
+ return good_addr;
+ }
+
+ // Not strongly live
+ return 0;
+}
+
+uintptr_t ZBarrier::weak_load_barrier_on_phantom_oop_slow_path(uintptr_t addr) {
+ const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
+ if (ZHeap::heap()->is_object_live(good_addr)) {
+ return good_addr;
+ }
+
+ // Not live
+ return 0;
+}
+
+//
+// Keep alive barrier
+//
+uintptr_t ZBarrier::keep_alive_barrier_on_weak_oop_slow_path(uintptr_t addr) {
+ const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
+ assert(ZHeap::heap()->is_object_strongly_live(good_addr), "Should be live");
+ return good_addr;
+}
+
+uintptr_t ZBarrier::keep_alive_barrier_on_phantom_oop_slow_path(uintptr_t addr) {
+ const uintptr_t good_addr = weak_load_barrier_on_oop_slow_path(addr);
+ assert(ZHeap::heap()->is_object_live(good_addr), "Should be live");
+ return good_addr;
+}
+
+//
+// Mark barrier
+//
+uintptr_t ZBarrier::mark_barrier_on_oop_slow_path(uintptr_t addr) {
+ return mark<Strong, Overflow>(addr);
+}
+
+uintptr_t ZBarrier::mark_barrier_on_finalizable_oop_slow_path(uintptr_t addr) {
+ const uintptr_t good_addr = mark<Finalizable, Overflow>(addr);
+ if (ZAddress::is_good(addr)) {
+ // If the oop was already strongly marked/good, then we do
+ // not want to downgrade it to finalizable marked/good.
+ return good_addr;
+ }
+
+ // Make the oop finalizable marked/good, instead of normal marked/good.
+ // This is needed because an object might first becomes finalizable
+ // marked by the GC, and then loaded by a mutator thread. In this case,
+ // the mutator thread must be able to tell that the object needs to be
+ // strongly marked. The finalizable bit in the oop exists to make sure
+ // that a load of a finalizable marked oop will fall into the barrier
+ // slow path so that we can mark the object as strongly reachable.
+ return ZAddress::finalizable_good(good_addr);
+}
+
+uintptr_t ZBarrier::mark_barrier_on_root_oop_slow_path(uintptr_t addr) {
+ assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
+ assert(during_mark(), "Invalid phase");
+
+ // Mark
+ return mark<Strong, Publish>(addr);
+}
+
+//
+// Relocate barrier
+//
+uintptr_t ZBarrier::relocate_barrier_on_root_oop_slow_path(uintptr_t addr) {
+ assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
+ assert(during_relocate(), "Invalid phase");
+
+ // Relocate
+ return relocate(addr);
+}
+
+//
+// Narrow oop variants, never used.
+//
+oop ZBarrier::load_barrier_on_oop_field(volatile narrowOop* p) {
+ ShouldNotReachHere();
+ return NULL;
+}
+
+oop ZBarrier::load_barrier_on_oop_field_preloaded(volatile narrowOop* p, oop o) {
+ ShouldNotReachHere();
+ return NULL;
+}
+
+void ZBarrier::load_barrier_on_oop_array(volatile narrowOop* p, size_t length) {
+ ShouldNotReachHere();
+}
+
+oop ZBarrier::load_barrier_on_weak_oop_field_preloaded(volatile narrowOop* p, oop o) {
+ ShouldNotReachHere();
+ return NULL;
+}
+
+oop ZBarrier::load_barrier_on_phantom_oop_field_preloaded(volatile narrowOop* p, oop o) {
+ ShouldNotReachHere();
+ return NULL;
+}
+
+oop ZBarrier::weak_load_barrier_on_oop_field_preloaded(volatile narrowOop* p, oop o) {
+ ShouldNotReachHere();
+ return NULL;
+}
+
+oop ZBarrier::weak_load_barrier_on_weak_oop_field_preloaded(volatile narrowOop* p, oop o) {
+ ShouldNotReachHere();
+ return NULL;
+}
+
+oop ZBarrier::weak_load_barrier_on_phantom_oop_field_preloaded(volatile narrowOop* p, oop o) {
+ ShouldNotReachHere();
+ return NULL;
+}