src/hotspot/share/compiler/oopMap.hpp

/*
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 * 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.
 *
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#ifndef SHARE_COMPILER_OOPMAP_HPP
#define SHARE_COMPILER_OOPMAP_HPP

#include "code/compressedStream.hpp"
#include "code/vmreg.hpp"
#include "memory/allocation.hpp"
#include "memory/iterator.hpp"
#include "oops/oopsHierarchy.hpp"
#include "utilities/checkedCast.hpp"
#include "utilities/growableArray.hpp"

// Interface for generating the frame map for compiled code.  A frame map
// describes for a specific pc whether each register and frame stack slot is:
//   Oop         - A GC root for current frame
//   Dead        - Dead; can be Zapped for debugging
//   CalleeXX    - Callee saved; also describes which caller register is saved
//   DerivedXX   - A derived oop; original oop is described.
//
// OopMapValue describes a single OopMap entry

enum class DerivedPointerIterationMode;
class frame;
class RegisterMap;
class OopClosure;
class CodeBlob;
class ImmutableOopMap;

enum class derived_base : intptr_t {};
enum class derived_pointer : intptr_t {};

class OopMapValue: public StackObj {
  friend class VMStructs;
private:
  unsigned short _value;
  unsigned short value() const                      { return _value; }
  void set_value(unsigned short value)              { _value = value; }
  short _content_reg;

public:
  // Constants
  enum { type_bits                = 2,
         register_bits            = BitsPerShort - type_bits };

  enum { type_shift               = 0,
         register_shift           = type_bits };

  enum { type_mask                = right_n_bits(type_bits),
         type_mask_in_place       = type_mask << type_shift,
         register_mask            = right_n_bits(register_bits),
         register_mask_in_place   = register_mask << register_shift };

  enum oop_types {
         oop_value,
         narrowoop_value,
         callee_saved_value,
         derived_oop_value,
         unused_value = -1          // Only used as a sentinel value
  };

  // Constructors
  OopMapValue () { set_value(0); set_content_reg(VMRegImpl::Bad()); }
  OopMapValue (VMReg reg, oop_types t, VMReg reg2) {
    set_reg_type(reg, t);
    set_content_reg(reg2);
  }

 private:
  void set_reg_type(VMReg p, oop_types t) {
    set_value(checked_cast<unsigned short>((p->value() << register_shift) | t));
    assert(reg() == p, "sanity check" );
    assert(type() == t, "sanity check" );
  }

  void set_content_reg(VMReg r) {
    if (is_callee_saved()) {
      // This can never be a stack location, so we don't need to transform it.
      assert(r->is_reg(), "Trying to callee save a stack location");
    } else if (is_derived_oop()) {
      assert (r->is_valid(), "must have a valid VMReg");
    } else {
      assert (!r->is_valid(), "valid VMReg not allowed");
    }
    _content_reg = checked_cast<short>(r->value());
  }

 public:
  // Archiving
  void write_on(CompressedWriteStream* stream) {
    stream->write_int(value());
    if(is_callee_saved() || is_derived_oop()) {
      stream->write_int(checked_cast<int>(content_reg()->value()));
    }
  }

  void read_from(CompressedReadStream* stream) {
    set_value(checked_cast<unsigned short>(stream->read_int()));
    if (is_callee_saved() || is_derived_oop()) {
      set_content_reg(VMRegImpl::as_VMReg(stream->read_int(), true));
    }
  }

  // Querying
  bool is_oop()               { return mask_bits(value(), type_mask_in_place) == oop_value; }
  bool is_narrowoop()         { return mask_bits(value(), type_mask_in_place) == narrowoop_value; }
  bool is_callee_saved()      { return mask_bits(value(), type_mask_in_place) == callee_saved_value; }
  bool is_derived_oop()       { return mask_bits(value(), type_mask_in_place) == derived_oop_value; }

  VMReg reg() const { return VMRegImpl::as_VMReg(checked_cast<int>(mask_bits(value(), register_mask_in_place) >> register_shift)); }
  oop_types type() const      { return (oop_types)mask_bits(value(), type_mask_in_place); }

  static bool legal_vm_reg_name(VMReg p) {
    return (p->value()  == (p->value() & register_mask));
  }

  VMReg content_reg() const       { return VMRegImpl::as_VMReg(_content_reg, true); }

  // Returns offset from sp.
  int stack_offset() {
    assert(reg()->is_stack(), "must be stack location");
    return reg()->reg2stack();
  }

  void print_on(outputStream* st) const;
  void print() const;
};


class OopMap: public ResourceObj {
  friend class OopMapStream;
  friend class VMStructs;
  friend class OopMapSet;
  friend class OopMapSort;
 private:
  int  _pc_offset; // offset in the code that this OopMap corresponds to
  int  _omv_count; // number of OopMapValues in the stream
  int  _num_oops;  // number of oops
  int  _index;     // index in OopMapSet
  bool _has_derived_oops;
  CompressedWriteStream* _write_stream;

  DEBUG_ONLY( OopMapValue::oop_types* _locs_used; int _locs_length;)

  // Accessors
  int omv_count() const                       { return _omv_count; }
  void set_omv_count(int value)               { _omv_count = value; }
  void increment_count()                      { _omv_count++; }
  void increment_num_oops()                   { _num_oops++; }
  void set_has_derived_oops(bool value)       { _has_derived_oops = value; }
  CompressedWriteStream* write_stream() const { return _write_stream; }
  void set_write_stream(CompressedWriteStream* value) { _write_stream = value; }

  enum DeepCopyToken { _deep_copy_token };
  OopMap(DeepCopyToken, OopMap* source);  // used only by deep_copy

  void set_xxx(VMReg reg, OopMapValue::oop_types x, VMReg optional);

 public:
  OopMap(int frame_size, int arg_count);

  // pc-offset handling
  int offset() const     { return _pc_offset; }
  void set_offset(int o) { _pc_offset = o; }
  int count() const { return _omv_count; }
  int data_size() const  { return write_stream()->position(); }
  address data() const { return write_stream()->buffer(); }
  int num_oops() const { return _num_oops; }
  bool has_derived_oops() const { return _has_derived_oops; }
  int index() const { return _index; }

  // Construction
  // frame_size units are stack-slots (4 bytes) NOT intptr_t; we can name odd
  // slots to hold 4-byte values like ints and floats in the LP64 build.
  void set_oop  ( VMReg local);
  void set_narrowoop(VMReg local);
  void set_callee_saved( VMReg local, VMReg caller_machine_register );
  void set_derived_oop ( VMReg local, VMReg derived_from_local_register );

  int heap_size() const;
  void copy_data_to(address addr) const;
  void copy_and_sort_data_to(address addr) const;
  OopMap* deep_copy();

  bool legal_vm_reg_name(VMReg local) {
     return OopMapValue::legal_vm_reg_name(local);
  }

  // Printing
  void print_on(outputStream* st) const;
  void print() const;
  bool equals(const OopMap* other) const;
};

class OopMapSet : public ResourceObj {
  friend class VMStructs;
 private:
  GrowableArray<OopMap*> _list;

  int add(OopMap* value) { return _list.append(value); }

 public:
  OopMapSet();

  // returns the number of OopMaps in this OopMapSet
  int size() const            { return _list.length(); }
  // returns the OopMap at a given index
  OopMap* at(int index) const { return _list.at(index); }

  // Collect OopMaps.
  int add_gc_map(int pc, OopMap* map);

  // Methods oops_do() and all_do() filter out nullptr oops and
  // oop == CompressedOops::base() before passing oops
  // to closures.

  static const ImmutableOopMap* find_map(const CodeBlob* cb, address pc);
  static const ImmutableOopMap* find_map(const frame *fr);

  // Iterates through frame for a compiled method
  static void oops_do            (const frame* fr,
                                  const RegisterMap* reg_map,
                                  OopClosure* f,
                                  DerivedOopClosure* df);
  static void oops_do            (const frame* fr,
                                  const RegisterMap* reg_map,
                                  OopClosure* f,
                                  DerivedPointerIterationMode mode);
  static void update_register_map(const frame* fr, RegisterMap *reg_map);

#ifndef PRODUCT
  static void trace_codeblob_maps(const frame *fr, const RegisterMap *reg_map);
#endif

  // Printing
  void print_on(outputStream* st) const;
  void print() const;
};

class ImmutableOopMapBuilder;

class OopMapClosure : public Closure {
 public:
  virtual bool handle_type(OopMapValue::oop_types type) { return true; }
  virtual void do_value(VMReg reg, OopMapValue::oop_types type) = 0;
};

template <typename OopFnT, typename DerivedOopFnT, typename ValueFilterT>
class OopMapDo;

class ImmutableOopMap {
  friend class OopMapStream;
  friend class VMStructs;
  template <typename OopFnT, typename DerivedOopFnT, typename ValueFilterT>
  friend class OopMapDo;
#ifdef ASSERT
  friend class ImmutableOopMapBuilder;
#endif
private:
  int _count; // contains the number of entries in this OopMap
  int _num_oops;
  bool _has_derived_oops;

  address data_addr() const { return (address) this + sizeof(ImmutableOopMap); }
public:
  ImmutableOopMap(const OopMap* oopmap);

  int count() const { return _count; }
  int num_oops() const { return _num_oops; }
  bool has_derived_oops() const { return _has_derived_oops; }
  bool has_any(OopMapValue::oop_types type) const;

  int nr_of_bytes() const; // this is an expensive operation, only used in debug builds or in aot code generation

  void oops_do(const frame* fr, const RegisterMap* reg_map, OopClosure* f, DerivedOopClosure* df) const;
  void oops_do(const frame* fr, const RegisterMap* reg_map, OopClosure* f, DerivedPointerIterationMode derived_mode) const;
  void all_type_do(const frame *fr, OopMapValue::oop_types type, OopMapClosure* fn) const;
  void all_type_do(const frame *fr, OopMapClosure* fn) const;
  void update_register_map(const frame* fr, RegisterMap *reg_map) const;

  // Printing
  void print_on(outputStream* st) const;
  void print() const;
};

class ImmutableOopMapSet;
class ImmutableOopMap;
class OopMapSet;

class ImmutableOopMapPair {
  friend class VMStructs;
private:
  int _pc_offset; // program counter offset from the beginning of the method
  int _oopmap_offset; // offset in the data in the ImmutableOopMapSet where the ImmutableOopMap is located
public:
  ImmutableOopMapPair(int pc_offset, int oopmap_offset) : _pc_offset(pc_offset), _oopmap_offset(oopmap_offset) {
    assert(pc_offset >= 0 && oopmap_offset >= 0, "check");
  }
  const ImmutableOopMap* get_from(const ImmutableOopMapSet* set) const;

  int pc_offset() const { return _pc_offset; }
  int oopmap_offset() const { return _oopmap_offset; }
};

class ImmutableOopMapSet {
  friend class VMStructs;
private:
  int _count; // nr of ImmutableOopMapPairs in the Set
  int _size; // nr of bytes including ImmutableOopMapSet itself

  address data() const { return (address) this + sizeof(*this) + sizeof(ImmutableOopMapPair) * _count; }

public:
  void operator delete(void* p);

  ImmutableOopMapSet(const OopMapSet* oopmap_set, int size) : _count(oopmap_set->size()), _size(size) {}
  ~ImmutableOopMapSet() = default;

  ImmutableOopMap* oopmap_at_offset(int offset) const {
    assert(offset >= 0 && offset < _size, "must be within boundaries");
    address addr = data() + offset;
    return (ImmutableOopMap*) addr;
  }

  ImmutableOopMapPair* get_pairs() const { return (ImmutableOopMapPair*) ((address) this + sizeof(*this)); }

  static ImmutableOopMapSet* build_from(const OopMapSet* oopmap_set);

  int find_slot_for_offset(int pc_offset) const;
  const ImmutableOopMap* find_map_at_offset(int pc_offset) const;
  const ImmutableOopMap* find_map_at_slot(int slot, int pc_offset) const;

  const ImmutableOopMapPair* pair_at(int index) const { assert(index >= 0 && index < _count, "check"); return &get_pairs()[index]; }

  int count() const { return _count; }
  int nr_of_bytes() const { return _size; }

  void print_on(outputStream* st) const;
  void print() const;
};

class OopMapStream : public StackObj {
 private:
  CompressedReadStream _stream;
  int _size;
  int _position;
  bool _valid_omv;
  OopMapValue _omv;
  void find_next();

 public:
  OopMapStream(const OopMap* oop_map);
  OopMapStream(const ImmutableOopMap* oop_map);
  bool is_done()                        { if(!_valid_omv) { find_next(); } return !_valid_omv; }
  void next()                           { find_next(); }
  OopMapValue current()                 { return _omv; }
  int stream_position() const           { return _stream.position(); }
};

class ImmutableOopMapBuilder {
private:
  class Mapping;

private:
  const OopMapSet* _set;
  const OopMap* _empty;
  const OopMap* _last;
  int _empty_offset;
  int _last_offset;
  int _offset;
  int _required;
  Mapping* _mapping;
  ImmutableOopMapSet* _new_set;

  /* Used for bookkeeping when building ImmutableOopMaps */
  class Mapping : public ResourceObj {
  public:
    enum kind_t { OOPMAP_UNKNOWN = 0, OOPMAP_NEW = 1, OOPMAP_EMPTY = 2, OOPMAP_DUPLICATE = 3 };

    kind_t _kind;
    int _offset;
    int _size;
    const OopMap* _map;
    const OopMap* _other;

    Mapping() : _kind(OOPMAP_UNKNOWN), _offset(-1), _size(-1), _map(nullptr) {}

    void set(kind_t kind, int offset, int size, const OopMap* map, const OopMap* other = nullptr) {
      _kind = kind;
      _offset = offset;
      _size = size;
      _map = map;
      _other = other;
    }
  };

public:
  ImmutableOopMapBuilder(const OopMapSet* set);

  int heap_size();
  ImmutableOopMapSet* build();
  ImmutableOopMapSet* generate_into(address buffer);
private:
  bool is_empty(const OopMap* map) const {
    return map->count() == 0;
  }

  bool is_last_duplicate(const OopMap* map) {
    if (_last != nullptr && _last->count() > 0 && _last->equals(map)) {
      return true;
    }
    return false;
  }

#ifdef ASSERT
  void verify(address buffer, int size, const ImmutableOopMapSet* set);
#endif

  bool has_empty() const {
    return _empty_offset != -1;
  }

  int size_for(const OopMap* map) const;
  void fill_pair(ImmutableOopMapPair* pair, const OopMap* map, int offset, const ImmutableOopMapSet* set);
  int fill_map(ImmutableOopMapPair* pair, const OopMap* map, int offset, const ImmutableOopMapSet* set);
  void fill(ImmutableOopMapSet* set, int size);
};

class SkipNullValue {
public:
  static inline bool should_skip(void* val);
};

class IncludeAllValues {
public:
  static bool should_skip(void* value) { return false; }
};

template <typename OopFnT, typename DerivedOopFnT, typename ValueFilterT>
class OopMapDo {
private:
  OopFnT* _oop_fn;
  DerivedOopFnT* _derived_oop_fn;
public:
  OopMapDo(OopFnT* oop_fn, DerivedOopFnT* derived_oop_fn) : _oop_fn(oop_fn), _derived_oop_fn(derived_oop_fn) {}
  template <typename RegisterMapT>
  void oops_do(const frame* fr, const RegisterMapT* reg_map, const ImmutableOopMap* oopmap);
private:
  template <typename RegisterMapT>
  void iterate_oops_do(const frame *fr, const RegisterMapT *reg_map, const ImmutableOopMap* oopmap);
};

// Derived pointer support. This table keeps track of all derived points on a
// stack.  It is cleared before each scavenge/GC.  During the traversal of all
// oops, it is filled in with references to all locations that contains a
// derived oop (assumed to be very few).  When the GC is complete, the derived
// pointers are updated based on their base pointers new value and an offset.
#if COMPILER2_OR_JVMCI
class DerivedPointerTable : public AllStatic {
  friend class VMStructs;
 private:
  class Entry;
  static bool _active;                                           // do not record pointers for verify pass etc.

 public:
  static void clear();                                           // Called before scavenge/GC
  static void add(derived_pointer* derived, derived_base* base); // Called during scavenge/GC
  static void update_pointers();                                 // Called after  scavenge/GC
  static bool is_empty();
  static bool is_active()                    { return _active; }
  static void set_active(bool value)         { _active = value; }
};

// A utility class to temporarily "deactivate" the DerivedPointerTable.
// (Note: clients are responsible for any MT-safety issues)
class DerivedPointerTableDeactivate: public StackObj {
 private:
  bool _active;
 public:
  DerivedPointerTableDeactivate() {
    _active = DerivedPointerTable::is_active();
    if (_active) {
      DerivedPointerTable::set_active(false);
    }
  }

  ~DerivedPointerTableDeactivate() {
    assert(!DerivedPointerTable::is_active(),
           "Inconsistency: not MT-safe");
    if (_active) {
      DerivedPointerTable::set_active(true);
    }
  }
};
#endif // COMPILER2_OR_JVMCI

#endif // SHARE_COMPILER_OOPMAP_HPP