src/hotspot/share/gc/z/zBarrier.cpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2015, 2019, 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 "memory/iterator.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 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<follow, 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");
   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<Follow, 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(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_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<Follow, Strong, Overflow>(addr);
 }

 uintptr_t ZBarrier::mark_barrier_on_finalizable_oop_slow_path(uintptr_t addr) {
   const uintptr_t good_addr = mark<Follow, 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<Follow, Strong, Publish>(addr);
 }

 uintptr_t ZBarrier::mark_barrier_on_invisible_root_oop_slow_path(uintptr_t addr) {
   assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
   assert(during_mark(), "Invalid phase");

   // Mark
   return mark<DontFollow, 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;
 }
	/*
	* Copyright (c) 2015, 2019, 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 "memory/iterator.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 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<follow, 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");
	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<Follow, 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(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_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<Follow, Strong, Overflow>(addr);
	}

	uintptr_t ZBarrier::mark_barrier_on_finalizable_oop_slow_path(uintptr_t addr) {
	const uintptr_t good_addr = mark<Follow, 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<Follow, Strong, Publish>(addr);
	}

	uintptr_t ZBarrier::mark_barrier_on_invisible_root_oop_slow_path(uintptr_t addr) {
	assert(SafepointSynchronize::is_at_safepoint(), "Should be at safepoint");
	assert(during_mark(), "Invalid phase");

	// Mark
	return mark<DontFollow, 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;
	}