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Java example source code file (vframe.hpp)

This example Java source code file (vframe.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

basiclock, codeblob, debuginformationrecorder\:\:serialized_null, growablearray, javathread, javathreadstate, method, monitorinfo, null, product, registermap, resourceobj, share_vm_runtime_vframe_hpp, stackvaluecollection

The vframe.hpp Java example source code

/*
 * Copyright (c) 1997, 2013, 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_VM_RUNTIME_VFRAME_HPP
#define SHARE_VM_RUNTIME_VFRAME_HPP

#include "code/debugInfo.hpp"
#include "code/debugInfoRec.hpp"
#include "code/location.hpp"
#include "oops/oop.hpp"
#include "runtime/frame.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/stackValue.hpp"
#include "runtime/stackValueCollection.hpp"
#include "utilities/growableArray.hpp"

// vframes are virtual stack frames representing source level activations.
// A single frame may hold several source level activations in the case of
// optimized code. The debugging stored with the optimized code enables
// us to unfold a frame as a stack of vframes.
// A cVFrame represents an activation of a non-java method.

// The vframe inheritance hierarchy:
// - vframe
//   - javaVFrame
//     - interpretedVFrame
//     - compiledVFrame     ; (used for both compiled Java methods and native stubs)
//   - externalVFrame
//     - entryVFrame        ; special frame created when calling Java from C

// - BasicLock

class vframe: public ResourceObj {
 protected:
  frame        _fr;      // Raw frame behind the virtual frame.
  RegisterMap  _reg_map; // Register map for the raw frame (used to handle callee-saved registers).
  JavaThread*  _thread;  // The thread owning the raw frame.

  vframe(const frame* fr, const RegisterMap* reg_map, JavaThread* thread);
  vframe(const frame* fr, JavaThread* thread);
 public:
  // Factory method for creating vframes
  static vframe* new_vframe(const frame* f, const RegisterMap *reg_map, JavaThread* thread);

  // Accessors
  frame              fr()           const { return _fr;       }
  CodeBlob*          cb()         const { return _fr.cb();  }
  nmethod*           nm()         const {
      assert( cb() != NULL && cb()->is_nmethod(), "usage");
      return (nmethod*) cb();
  }

// ???? Does this need to be a copy?
  frame*             frame_pointer() { return &_fr;       }
  const RegisterMap* register_map() const { return &_reg_map; }
  JavaThread*        thread()       const { return _thread;   }

  // Returns the sender vframe
  virtual vframe* sender() const;

  // Returns the next javaVFrame on the stack (skipping all other kinds of frame)
  javaVFrame *java_sender() const;

  // Answers if the this is the top vframe in the frame, i.e., if the sender vframe
  // is in the caller frame
  virtual bool is_top() const { return true; }

  // Returns top vframe within same frame (see is_top())
  virtual vframe* top() const;

  // Type testing operations
  virtual bool is_entry_frame()       const { return false; }
  virtual bool is_java_frame()        const { return false; }
  virtual bool is_interpreted_frame() const { return false; }
  virtual bool is_compiled_frame()    const { return false; }

#ifndef PRODUCT
  // printing operations
  virtual void print_value() const;
  virtual void print();
#endif
};


class javaVFrame: public vframe {
 public:
  // JVM state
  virtual Method*                      method()         const = 0;
  virtual int                          bci()            const = 0;
  virtual StackValueCollection*        locals()         const = 0;
  virtual StackValueCollection*        expressions()    const = 0;
  // the order returned by monitors() is from oldest -> youngest#4418568
  virtual GrowableArray<MonitorInfo*>* monitors()       const = 0;

  // Debugging support via JVMTI.
  // NOTE that this is not guaranteed to give correct results for compiled vframes.
  // Deoptimize first if necessary.
  virtual void set_locals(StackValueCollection* values) const = 0;

  // Test operation
  bool is_java_frame() const { return true; }

 protected:
  javaVFrame(const frame* fr, const RegisterMap* reg_map, JavaThread* thread) : vframe(fr, reg_map, thread) {}
  javaVFrame(const frame* fr, JavaThread* thread) : vframe(fr, thread) {}

 public:
  // casting
  static javaVFrame* cast(vframe* vf) {
    assert(vf == NULL || vf->is_java_frame(), "must be java frame");
    return (javaVFrame*) vf;
  }

  // Return an array of monitors locked by this frame in the youngest to oldest order
  GrowableArray<MonitorInfo*>* locked_monitors();

  // printing used during stack dumps
  void print_lock_info_on(outputStream* st, int frame_count);
  void print_lock_info(int frame_count) { print_lock_info_on(tty, frame_count); }

#ifndef PRODUCT
 public:
  // printing operations
  void print();
  void print_value() const;
  void print_activation(int index) const;

  // verify operations
  virtual void verify() const;

  // Structural compare
  bool structural_compare(javaVFrame* other);
#endif
  friend class vframe;
};

class interpretedVFrame: public javaVFrame {
 public:
  // JVM state
  Method*                      method()         const;
  int                          bci()            const;
  StackValueCollection*        locals()         const;
  StackValueCollection*        expressions()    const;
  GrowableArray<MonitorInfo*>* monitors()       const;

  void set_locals(StackValueCollection* values) const;

  // Test operation
  bool is_interpreted_frame() const { return true; }

 protected:
  interpretedVFrame(const frame* fr, const RegisterMap* reg_map, JavaThread* thread) : javaVFrame(fr, reg_map, thread) {};

 public:
  // Accessors for Byte Code Pointer
  u_char* bcp() const;
  void set_bcp(u_char* bcp);

  // casting
  static interpretedVFrame* cast(vframe* vf) {
    assert(vf == NULL || vf->is_interpreted_frame(), "must be interpreted frame");
    return (interpretedVFrame*) vf;
  }

 private:
  static const int bcp_offset;
  intptr_t* locals_addr_at(int offset) const;

  // returns where the parameters starts relative to the frame pointer
  int start_of_parameters() const;

#ifndef PRODUCT
 public:
  // verify operations
  void verify() const;
#endif
  friend class vframe;
};


class externalVFrame: public vframe {
 protected:
  externalVFrame(const frame* fr, const RegisterMap* reg_map, JavaThread* thread) : vframe(fr, reg_map, thread) {}

#ifndef PRODUCT
 public:
  // printing operations
  void print_value() const;
  void print();
#endif
  friend class vframe;
};

class entryVFrame: public externalVFrame {
 public:
  bool is_entry_frame() const { return true; }

 protected:
  entryVFrame(const frame* fr, const RegisterMap* reg_map, JavaThread* thread);

 public:
  // casting
  static entryVFrame* cast(vframe* vf) {
    assert(vf == NULL || vf->is_entry_frame(), "must be entry frame");
    return (entryVFrame*) vf;
  }

#ifndef PRODUCT
 public:
  // printing
  void print_value() const;
  void print();
#endif
  friend class vframe;
};


// A MonitorInfo is a ResourceObject that describes a the pair:
// 1) the owner of the monitor
// 2) the monitor lock
class MonitorInfo : public ResourceObj {
 private:
  oop        _owner; // the object owning the monitor
  BasicLock* _lock;
  oop        _owner_klass; // klass (mirror) if owner was scalar replaced
  bool       _eliminated;
  bool       _owner_is_scalar_replaced;
 public:
  // Constructor
  MonitorInfo(oop owner, BasicLock* lock, bool eliminated, bool owner_is_scalar_replaced) {
    if (!owner_is_scalar_replaced) {
      _owner = owner;
      _owner_klass = NULL;
    } else {
      assert(eliminated, "monitor should be eliminated for scalar replaced object");
      _owner = NULL;
      _owner_klass = owner;
    }
    _lock  = lock;
    _eliminated = eliminated;
    _owner_is_scalar_replaced = owner_is_scalar_replaced;
  }
  // Accessors
  oop        owner() const {
    assert(!_owner_is_scalar_replaced, "should not be called for scalar replaced object");
    return _owner;
  }
  oop   owner_klass() const {
    assert(_owner_is_scalar_replaced, "should not be called for not scalar replaced object");
    return _owner_klass;
  }
  BasicLock* lock()  const { return _lock;  }
  bool eliminated()  const { return _eliminated; }
  bool owner_is_scalar_replaced()  const { return _owner_is_scalar_replaced; }
};

class vframeStreamCommon : StackObj {
 protected:
  // common
  frame        _frame;
  JavaThread*  _thread;
  RegisterMap  _reg_map;
  enum { interpreted_mode, compiled_mode, at_end_mode } _mode;

  int _sender_decode_offset;

  // Cached information
  Method* _method;
  int       _bci;

  // Should VM activations be ignored or not
  bool _stop_at_java_call_stub;

  bool fill_in_compiled_inlined_sender();
  void fill_from_compiled_frame(int decode_offset);
  void fill_from_compiled_native_frame();

  void found_bad_method_frame();

  void fill_from_interpreter_frame();
  bool fill_from_frame();

  // Helper routine for security_get_caller_frame
  void skip_prefixed_method_and_wrappers();

 public:
  // Constructor
  vframeStreamCommon(JavaThread* thread) : _reg_map(thread, false) {
    _thread = thread;
  }

  // Accessors
  Method* method() const { return _method; }
  int bci() const { return _bci; }
  intptr_t* frame_id() const { return _frame.id(); }
  address frame_pc() const { return _frame.pc(); }

  CodeBlob*          cb()         const { return _frame.cb();  }
  nmethod*           nm()         const {
      assert( cb() != NULL && cb()->is_nmethod(), "usage");
      return (nmethod*) cb();
  }

  // Frame type
  bool is_interpreted_frame() const { return _frame.is_interpreted_frame(); }
  bool is_entry_frame() const       { return _frame.is_entry_frame(); }

  // Iteration
  void next() {
    // handle frames with inlining
    if (_mode == compiled_mode    && fill_in_compiled_inlined_sender()) return;

    // handle general case
    do {
      _frame = _frame.sender(&_reg_map);
    } while (!fill_from_frame());
  }
  void security_next();

  bool at_end() const { return _mode == at_end_mode; }

  // Implements security traversal. Skips depth no. of frame including
  // special security frames and prefixed native methods
  void security_get_caller_frame(int depth);

  // Helper routine for JVM_LatestUserDefinedLoader -- needed for 1.4
  // reflection implementation
  void skip_reflection_related_frames();
};

class vframeStream : public vframeStreamCommon {
 public:
  // Constructors
  vframeStream(JavaThread* thread, bool stop_at_java_call_stub = false)
    : vframeStreamCommon(thread) {
    _stop_at_java_call_stub = stop_at_java_call_stub;

    if (!thread->has_last_Java_frame()) {
      _mode = at_end_mode;
      return;
    }

    _frame = _thread->last_frame();
    while (!fill_from_frame()) {
      _frame = _frame.sender(&_reg_map);
    }
  }

  // top_frame may not be at safepoint, start with sender
  vframeStream(JavaThread* thread, frame top_frame, bool stop_at_java_call_stub = false);
};


inline bool vframeStreamCommon::fill_in_compiled_inlined_sender() {
  if (_sender_decode_offset == DebugInformationRecorder::serialized_null) {
    return false;
  }
  fill_from_compiled_frame(_sender_decode_offset);
  return true;
}


inline void vframeStreamCommon::fill_from_compiled_frame(int decode_offset) {
  _mode = compiled_mode;

  // Range check to detect ridiculous offsets.
  if (decode_offset == DebugInformationRecorder::serialized_null ||
      decode_offset < 0 ||
      decode_offset >= nm()->scopes_data_size()) {
    // 6379830 AsyncGetCallTrace sometimes feeds us wild frames.
    // If we attempt to read nmethod::scopes_data at serialized_null (== 0),
    // or if we read some at other crazy offset,
    // we will decode garbage and make wild references into the heap,
    // leading to crashes in product mode.
    // (This isn't airtight, of course, since there are internal
    // offsets which are also crazy.)
#ifdef ASSERT
    if (WizardMode) {
      tty->print_cr("Error in fill_from_frame: pc_desc for "
                    INTPTR_FORMAT " not found or invalid at %d",
                    _frame.pc(), decode_offset);
      nm()->print();
      nm()->method()->print_codes();
      nm()->print_code();
      nm()->print_pcs();
    }
#endif
    // Provide a cheap fallback in product mode.  (See comment above.)
    found_bad_method_frame();
    fill_from_compiled_native_frame();
    return;
  }

  // Decode first part of scopeDesc
  DebugInfoReadStream buffer(nm(), decode_offset);
  _sender_decode_offset = buffer.read_int();
  _method               = buffer.read_method();
  _bci                  = buffer.read_bci();

  assert(_method->is_method(), "checking type of decoded method");
}

// The native frames are handled specially. We do not rely on ScopeDesc info
// since the pc might not be exact due to the _last_native_pc trick.
inline void vframeStreamCommon::fill_from_compiled_native_frame() {
  _mode = compiled_mode;
  _sender_decode_offset = DebugInformationRecorder::serialized_null;
  _method = nm()->method();
  _bci = 0;
}

inline bool vframeStreamCommon::fill_from_frame() {
  // Interpreted frame
  if (_frame.is_interpreted_frame()) {
    fill_from_interpreter_frame();
    return true;
  }

  // Compiled frame

  if (cb() != NULL && cb()->is_nmethod()) {
    if (nm()->is_native_method()) {
      // Do not rely on scopeDesc since the pc might be unprecise due to the _last_native_pc trick.
      fill_from_compiled_native_frame();
    } else {
      PcDesc* pc_desc = nm()->pc_desc_at(_frame.pc());
      int decode_offset;
      if (pc_desc == NULL) {
        // Should not happen, but let fill_from_compiled_frame handle it.

        // If we are trying to walk the stack of a thread that is not
        // at a safepoint (like AsyncGetCallTrace would do) then this is an
        // acceptable result. [ This is assuming that safe_for_sender
        // is so bullet proof that we can trust the frames it produced. ]
        //
        // So if we see that the thread is not safepoint safe
        // then simply produce the method and a bci of zero
        // and skip the possibility of decoding any inlining that
        // may be present. That is far better than simply stopping (or
        // asserting. If however the thread is safepoint safe this
        // is the sign of a compiler bug  and we'll let
        // fill_from_compiled_frame handle it.


        JavaThreadState state = _thread->thread_state();

        // in_Java should be good enough to test safepoint safety
        // if state were say in_Java_trans then we'd expect that
        // the pc would have already been slightly adjusted to
        // one that would produce a pcDesc since the trans state
        // would be one that might in fact anticipate a safepoint

        if (state == _thread_in_Java ) {
          // This will get a method a zero bci and no inlining.
          // Might be nice to have a unique bci to signify this
          // particular case but for now zero will do.

          fill_from_compiled_native_frame();

          // There is something to be said for setting the mode to
          // at_end_mode to prevent trying to walk further up the
          // stack. There is evidence that if we walk any further
          // that we could produce a bad stack chain. However until
          // we see evidence that allowing this causes us to find
          // frames bad enough to cause segv's or assertion failures
          // we don't do it as while we may get a bad call chain the
          // probability is much higher (several magnitudes) that we
          // get good data.

          return true;
        }
        decode_offset = DebugInformationRecorder::serialized_null;
      } else {
        decode_offset = pc_desc->scope_decode_offset();
      }
      fill_from_compiled_frame(decode_offset);
    }
    return true;
  }

  // End of stack?
  if (_frame.is_first_frame() || (_stop_at_java_call_stub && _frame.is_entry_frame())) {
    _mode = at_end_mode;
    return true;
  }

  return false;
}


inline void vframeStreamCommon::fill_from_interpreter_frame() {
  Method* method = _frame.interpreter_frame_method();
  intptr_t  bcx    = _frame.interpreter_frame_bcx();
  int       bci    = method->validate_bci_from_bcx(bcx);
  // 6379830 AsyncGetCallTrace sometimes feeds us wild frames.
  if (bci < 0) {
    found_bad_method_frame();
    bci = 0;  // pretend it's on the point of entering
  }
  _mode   = interpreted_mode;
  _method = method;
  _bci    = bci;
}

#endif // SHARE_VM_RUNTIME_VFRAME_HPP

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