Quellcode-Bibliothek

^© Kompilation durch diese Firma

[Weder Korrektheit noch Funktionsfähigkeit der Software werden zugesichert.]

Datei: zBarrier.cpp Sprache: C

/*
* Copyright (c) 2015, 2022, 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 "classfile/javaClasses.hpp"
#include "gc/z/zBarrier.inline.hpp"
#include "gc/z/zHeap.inline.hpp"
#include "gc/z/zOop.inline.hpp"
#include "gc/z/zThread.inline.hpp"
#include "memory/iterator.inline.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/safepoint.hpp"
#include "utilities/debug.hpp"

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 gc_thread, bool follow, 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<gc_thread, follow, finalizable, publish>(good_addr);
  }

  if (finalizable) {
    // 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);
  }

  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");
  return ZHeap::heap()->remap_object(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");
  return ZHeap::heap()->relocate_object(addr);
}

uintptr_t ZBarrier::relocate_or_mark(uintptr_t addr) {
  return during_relocate() ? relocate(addr) : mark<AnyThread, Follow, Strong, Publish>(addr);
}

uintptr_t ZBarrier::relocate_or_mark_no_follow(uintptr_t addr) {
  return during_relocate() ? relocate(addr) : mark<AnyThread, DontFollow, 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);
}

uintptr_t ZBarrier::load_barrier_on_invisible_root_oop_slow_path(uintptr_t addr) {
  return relocate_or_mark_no_follow(addr);
}

void ZBarrier::load_barrier_on_oop_fields(oop o) {
  assert(ZAddress::is_good(ZOop::to_address(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_oop_slow_path(uintptr_t addr) {
  assert(during_mark(), "Invalid phase");

  // Mark
  return mark<AnyThread, Follow, Strong, Overflow>(addr);
}

uintptr_t ZBarrier::keep_alive_barrier_on_weak_oop_slow_path(uintptr_t addr) {
  assert(ZResurrection::is_blocked(), "This operation is only valid when resurrection is blocked");
  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) {
  assert(ZResurrection::is_blocked(), "This operation is only valid when resurrection is blocked");
  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) {
  assert(during_mark(), "Invalid phase");
  assert(ZThread::is_worker(), "Invalid thread");

  // Mark
  return mark<GCThread, Follow, Strong, Overflow>(addr);
}

uintptr_t ZBarrier::mark_barrier_on_finalizable_oop_slow_path(uintptr_t addr) {
  assert(during_mark(), "Invalid phase");
  assert(ZThread::is_worker(), "Invalid thread");

  // Mark
  return mark<GCThread, Follow, Finalizable, Overflow>(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;
}

#ifdef ASSERT

// ON_WEAK barriers should only ever be applied to j.l.r.Reference.referents.
void ZBarrier::verify_on_weak(volatile oop* referent_addr) {
  if (referent_addr != NULL) {
    uintptr_t base = (uintptr_t)referent_addr - java_lang_ref_Reference::referent_offset();
    oop obj = cast_to_oop(base);
    assert(oopDesc::is_oop(obj), "Verification failed for: ref " PTR_FORMAT " obj: " PTR_FORMAT, (uintptr_t)referent_addr, base);
    assert(java_lang_ref_Reference::is_referent_field(obj, java_lang_ref_Reference::referent_offset()), "Sanity");
  }
}

#endif

void ZLoadBarrierOopClosure::do_oop(oop* p) {
  ZBarrier::load_barrier_on_oop_field(p);
}

void ZLoadBarrierOopClosure::do_oop(narrowOop* p) {
  ShouldNotReachHere();
}

¤ Dauer der Verarbeitung: 0.18 Sekunden (vorverarbeitet) ¤

Download des Quellennavigators
Download des sprechenden Kalenders
in der Quellcodebibliothek suchen

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.