src/hotspot/share/code/scopeDesc.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_CODE_SCOPEDESC_HPP
#define SHARE_CODE_SCOPEDESC_HPP

#include "code/debugInfo.hpp"
#include "code/pcDesc.hpp"
#include "oops/method.hpp"
#include "utilities/growableArray.hpp"

// SimpleScopeDesc is used when all you need to extract from
// a given pc,nmethod pair is a Method* and a bci. This is
// quite a bit faster than allocating a full ScopeDesc, but
// very limited in abilities.

class SimpleScopeDesc : public StackObj {
 private:
  Method* _method;
  int _bci;

 public:
  SimpleScopeDesc(nmethod* code, address pc) {
    PcDesc* pc_desc = code->pc_desc_at(pc);
    assert(pc_desc != nullptr, "Must be able to find matching PcDesc");
    // save this here so we only have to look up the PcDesc once
    DebugInfoReadStream buffer(code, pc_desc->scope_decode_offset());
    int ignore_sender = buffer.read_int();
    _method           = buffer.read_method();
    _bci              = buffer.read_bci();
  }

  Method* method() { return _method; }
  int bci() { return _bci; }
};

// ScopeDescs contain the information that makes source-level debugging of
// nmethods possible; each scopeDesc describes a method activation

class ScopeDesc : public ResourceObj {
 public:
  // Constructor
  ScopeDesc(const nmethod* code, PcDesc* pd, bool ignore_objects = false);

  // Direct access to scope
  ScopeDesc* at_offset(int decode_offset) { return new ScopeDesc(this, decode_offset); }

  // JVM state
  Method* method()      const { return _method; }
  int          bci()      const { return _bci;    }
  bool should_reexecute() const { return _reexecute; }
  bool rethrow_exception() const { return _rethrow_exception; }
  bool return_oop()       const { return _return_oop; }
  // Returns true if one or more NoEscape or ArgEscape objects exist in
  // any of the scopes at compiled pc.
  bool has_ea_local_in_scope() const { return _has_ea_local_in_scope; }
  bool arg_escape()       const { return _arg_escape; }

  GrowableArray<ScopeValue*>*   locals();
  GrowableArray<ScopeValue*>*   expressions();
  GrowableArray<MonitorValue*>* monitors();
  GrowableArray<ScopeValue*>*   objects();

  // Stack walking, returns nullptr if this is the outer most scope.
  ScopeDesc* sender() const;

  // Returns where the scope was decoded
  int decode_offset() const { return _decode_offset; }

  int sender_decode_offset() const { return _sender_decode_offset; }

  // Tells whether sender() returns nullptr
  bool is_top() const;

 private:
  void initialize(const ScopeDesc* parent, int decode_offset);
  // Alternative constructors
  ScopeDesc(const ScopeDesc* parent);
  ScopeDesc(const ScopeDesc* parent, int decode_offset);

  // JVM state
  Method*       _method;
  int           _bci;
  bool          _reexecute;
  bool          _rethrow_exception;
  bool          _return_oop;
  bool          _has_ea_local_in_scope;       // One or more NoEscape or ArgEscape objects exist in
                                              // any of the scopes at compiled pc.
  bool          _arg_escape;                  // Compiled Java call in youngest scope passes ArgEscape

  // Decoding offsets
  int _decode_offset;
  int _sender_decode_offset;
  int _locals_decode_offset;
  int _expressions_decode_offset;
  int _monitors_decode_offset;

  // Object pool
  GrowableArray<ScopeValue*>* _objects;

  // Nmethod information
  const nmethod* _code;

  // Decoding operations
  void decode_body();
  GrowableArray<ScopeValue*>* decode_scope_values(int decode_offset);
  GrowableArray<MonitorValue*>* decode_monitor_values(int decode_offset);
  GrowableArray<ScopeValue*>* decode_object_values(int decode_offset);

  DebugInfoReadStream* stream_at(int decode_offset) const;


 public:
  // Verification
  void verify();
  GrowableArray<ScopeValue*>* objects_to_rematerialize(frame& frm, RegisterMap& map);

#ifndef PRODUCT
 public:
  // Printing support
  void print_on(outputStream* st) const;
  void print_on(outputStream* st, PcDesc* pd) const;
  void print_value_on(outputStream* st) const;
#endif
};

#endif // SHARE_CODE_SCOPEDESC_HPP