src/hotspot/share/gc/g1/g1HeapRegionAttr.hpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2014, 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.
  *
  */

 #ifndef SHARE_GC_G1_G1HEAPREGIONATTR_HPP
 #define SHARE_GC_G1_G1HEAPREGIONATTR_HPP

 #include "gc/g1/g1BiasedArray.hpp"
 #include "gc/g1/heapRegion.hpp"

 // Per-region attributes often used during garbage collection to avoid costly
 // lookups for that information all over the place.
 struct G1HeapRegionAttr {
 public:
   // We use different types to represent the state value depending on platform as
   // some have issues loading parts of words.
 #ifdef SPARC
   typedef int32_t region_type_t;
   typedef uint32_t needs_remset_update_t;
 #else
   typedef int8_t region_type_t;
   typedef uint8_t needs_remset_update_t;
 #endif

 private:
   needs_remset_update_t _needs_remset_update;
   region_type_t _type;

 public:
   // Selection of the values for the _type field were driven to micro-optimize the
   // encoding and frequency of the checks.
   // The most common check for a given reference is whether the region is in the
   // collection set or not, and which generation this region is in.
   // The selected encoding allows us to use a single check (> NotInCSet) for the
   // former.
   //
   // The other values are used for objects in regions requiring various special handling,
   // eager reclamation of humongous objects or optional regions.
   static const region_type_t Optional     =  -3;    // The region is optional not in the current collection set.
   static const region_type_t Humongous    =  -2;    // The region is a humongous candidate not in the current collection set.
   static const region_type_t NotInCSet    =  -1;    // The region is not in the collection set.
   static const region_type_t Young        =   0;    // The region is in the collection set and a young region.
   static const region_type_t Old          =   1;    // The region is in the collection set and an old region.
   static const region_type_t Num          =   2;

   G1HeapRegionAttr(region_type_t type = NotInCSet, bool needs_remset_update = false) :
     _needs_remset_update(needs_remset_update), _type(type) {

     assert(is_valid(), "Invalid type %d", _type);
   }

   region_type_t type() const           { return _type; }

   const char* get_type_str() const {
     switch (type()) {
       case Optional: return "Optional";
       case Humongous: return "Humongous";
       case NotInCSet: return "NotInCSet";
       case Young: return "Young";
       case Old: return "Old";
       default: ShouldNotReachHere(); return "";
     }
   }

   bool needs_remset_update() const     { return _needs_remset_update != 0; }

   void set_old()                       { _type = Old; }
   void clear_humongous()               {
     assert(is_humongous() || !is_in_cset(), "must be");
     _type = NotInCSet;
   }
   void set_has_remset(bool value)      { _needs_remset_update = value ? 1 : 0; }

   bool is_in_cset_or_humongous() const { return is_in_cset() || is_humongous(); }
   bool is_in_cset() const              { return type() >= Young; }

   bool is_humongous() const            { return type() == Humongous; }
   bool is_young() const                { return type() == Young; }
   bool is_old() const                  { return type() == Old; }
   bool is_optional() const             { return type() == Optional; }

 #ifdef ASSERT
   bool is_default() const              { return type() == NotInCSet; }
   bool is_valid() const                { return (type() >= Optional && type() < Num); }
   bool is_valid_gen() const            { return (type() >= Young && type() <= Old); }
 #endif
 };

 // Table for all regions in the heap for above.
 //
 // We use this to speed up reference processing during young collection and
 // quickly reclaim humongous objects. For the latter, at the start of GC, by adding
 // it as a humongous region we enable special handling for that region. During the
 // reference iteration closures, when we see a humongous region, we then simply mark
 // it as referenced, i.e. live, and remove it from this table to prevent further
 // processing on it.
 //
 // This means that this does NOT completely correspond to the information stored
 // in a HeapRegion, but only to what is interesting for the current young collection.
 class G1HeapRegionAttrBiasedMappedArray : public G1BiasedMappedArray<G1HeapRegionAttr> {
  protected:
   G1HeapRegionAttr default_value() const { return G1HeapRegionAttr(G1HeapRegionAttr::NotInCSet); }
  public:
   void set_optional(uintptr_t index, bool needs_remset_update) {
     assert(get_by_index(index).is_default(),
            "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
     set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Optional, needs_remset_update));
   }

   void set_humongous(uintptr_t index, bool needs_remset_update) {
     assert(get_by_index(index).is_default(),
            "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
     set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Humongous, needs_remset_update));
   }

   void clear_humongous(uintptr_t index) {
     get_ref_by_index(index)->clear_humongous();
   }

   void set_has_remset(uintptr_t index, bool needs_remset_update) {
     get_ref_by_index(index)->set_has_remset(needs_remset_update);
   }

   void set_in_young(uintptr_t index) {
     assert(get_by_index(index).is_default(),
            "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
     set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Young, true));
   }

   void set_in_old(uintptr_t index, bool needs_remset_update) {
     assert(get_by_index(index).is_default(),
            "Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
     set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Old, needs_remset_update));
   }

   bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); }
   bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); }
   bool is_in_cset(const HeapRegion* hr) const { return get_by_index(hr->hrm_index()).is_in_cset(); }
   G1HeapRegionAttr at(HeapWord* addr) const { return get_by_address(addr); }
   void clear() { G1BiasedMappedArray<G1HeapRegionAttr>::clear(); }
   void clear(const HeapRegion* hr) { return set_by_index(hr->hrm_index(), G1HeapRegionAttr(G1HeapRegionAttr::NotInCSet)); }
 };

 #endif // SHARE_GC_G1_G1HEAPREGIONATTR_HPP
	/*
	* Copyright (c) 2014, 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.
	*
	*/

	#ifndef SHARE_GC_G1_G1HEAPREGIONATTR_HPP
	#define SHARE_GC_G1_G1HEAPREGIONATTR_HPP

	#include "gc/g1/g1BiasedArray.hpp"
	#include "gc/g1/heapRegion.hpp"

	// Per-region attributes often used during garbage collection to avoid costly
	// lookups for that information all over the place.
	struct G1HeapRegionAttr {
	public:
	// We use different types to represent the state value depending on platform as
	// some have issues loading parts of words.
	#ifdef SPARC
	typedef int32_t region_type_t;
	typedef uint32_t needs_remset_update_t;
	#else
	typedef int8_t region_type_t;
	typedef uint8_t needs_remset_update_t;
	#endif

	private:
	needs_remset_update_t _needs_remset_update;
	region_type_t _type;

	public:
	// Selection of the values for the _type field were driven to micro-optimize the
	// encoding and frequency of the checks.
	// The most common check for a given reference is whether the region is in the
	// collection set or not, and which generation this region is in.
	// The selected encoding allows us to use a single check (> NotInCSet) for the
	// former.
	//
	// The other values are used for objects in regions requiring various special handling,
	// eager reclamation of humongous objects or optional regions.
	static const region_type_t Optional = -3; // The region is optional not in the current collection set.
	static const region_type_t Humongous = -2; // The region is a humongous candidate not in the current collection set.
	static const region_type_t NotInCSet = -1; // The region is not in the collection set.
	static const region_type_t Young = 0; // The region is in the collection set and a young region.
	static const region_type_t Old = 1; // The region is in the collection set and an old region.
	static const region_type_t Num = 2;

	G1HeapRegionAttr(region_type_t type = NotInCSet, bool needs_remset_update = false) :
	_needs_remset_update(needs_remset_update), _type(type) {

	assert(is_valid(), "Invalid type %d", _type);
	}

	region_type_t type() const { return _type; }

	const char* get_type_str() const {
	switch (type()) {
	case Optional: return "Optional";
	case Humongous: return "Humongous";
	case NotInCSet: return "NotInCSet";
	case Young: return "Young";
	case Old: return "Old";
	default: ShouldNotReachHere(); return "";
	}
	}

	bool needs_remset_update() const { return _needs_remset_update != 0; }

	void set_old() { _type = Old; }
	void clear_humongous() {
	assert(is_humongous() \|\| !is_in_cset(), "must be");
	_type = NotInCSet;
	}
	void set_has_remset(bool value) { _needs_remset_update = value ? 1 : 0; }

	bool is_in_cset_or_humongous() const { return is_in_cset() \|\| is_humongous(); }
	bool is_in_cset() const { return type() >= Young; }

	bool is_humongous() const { return type() == Humongous; }
	bool is_young() const { return type() == Young; }
	bool is_old() const { return type() == Old; }
	bool is_optional() const { return type() == Optional; }

	#ifdef ASSERT
	bool is_default() const { return type() == NotInCSet; }
	bool is_valid() const { return (type() >= Optional && type() < Num); }
	bool is_valid_gen() const { return (type() >= Young && type() <= Old); }
	#endif
	};

	// Table for all regions in the heap for above.
	//
	// We use this to speed up reference processing during young collection and
	// quickly reclaim humongous objects. For the latter, at the start of GC, by adding
	// it as a humongous region we enable special handling for that region. During the
	// reference iteration closures, when we see a humongous region, we then simply mark
	// it as referenced, i.e. live, and remove it from this table to prevent further
	// processing on it.
	//
	// This means that this does NOT completely correspond to the information stored
	// in a HeapRegion, but only to what is interesting for the current young collection.
	class G1HeapRegionAttrBiasedMappedArray : public G1BiasedMappedArray<G1HeapRegionAttr> {
	protected:
	G1HeapRegionAttr default_value() const { return G1HeapRegionAttr(G1HeapRegionAttr::NotInCSet); }
	public:
	void set_optional(uintptr_t index, bool needs_remset_update) {
	assert(get_by_index(index).is_default(),
	"Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
	set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Optional, needs_remset_update));
	}

	void set_humongous(uintptr_t index, bool needs_remset_update) {
	assert(get_by_index(index).is_default(),
	"Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
	set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Humongous, needs_remset_update));
	}

	void clear_humongous(uintptr_t index) {
	get_ref_by_index(index)->clear_humongous();
	}

	void set_has_remset(uintptr_t index, bool needs_remset_update) {
	get_ref_by_index(index)->set_has_remset(needs_remset_update);
	}

	void set_in_young(uintptr_t index) {
	assert(get_by_index(index).is_default(),
	"Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
	set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Young, true));
	}

	void set_in_old(uintptr_t index, bool needs_remset_update) {
	assert(get_by_index(index).is_default(),
	"Region attributes at index " INTPTR_FORMAT " should be default but is %s", index, get_by_index(index).get_type_str());
	set_by_index(index, G1HeapRegionAttr(G1HeapRegionAttr::Old, needs_remset_update));
	}

	bool is_in_cset_or_humongous(HeapWord* addr) const { return at(addr).is_in_cset_or_humongous(); }
	bool is_in_cset(HeapWord* addr) const { return at(addr).is_in_cset(); }
	bool is_in_cset(const HeapRegion* hr) const { return get_by_index(hr->hrm_index()).is_in_cset(); }
	G1HeapRegionAttr at(HeapWord* addr) const { return get_by_address(addr); }
	void clear() { G1BiasedMappedArray<G1HeapRegionAttr>::clear(); }
	void clear(const HeapRegion* hr) { return set_by_index(hr->hrm_index(), G1HeapRegionAttr(G1HeapRegionAttr::NotInCSet)); }
	};

	#endif // SHARE_GC_G1_G1HEAPREGIONATTR_HPP