hotspot/src/share/vm/prims/stackwalk.cpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2015, 2016, 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 "classfile/javaClasses.hpp"
 #include "classfile/javaClasses.inline.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "logging/log.hpp"
 #include "memory/oopFactory.hpp"
 #include "oops/oop.inline.hpp"
 #include "oops/objArrayOop.inline.hpp"
 #include "prims/stackwalk.hpp"
 #include "runtime/globals.hpp"
 #include "runtime/handles.inline.hpp"
 #include "runtime/javaCalls.hpp"
 #include "runtime/vframe.hpp"
 #include "utilities/globalDefinitions.hpp"

 // setup and cleanup actions
 void BaseFrameStream::setup_magic_on_entry(objArrayHandle frames_array) {
   frames_array->obj_at_put(magic_pos, _thread->threadObj());
   _anchor = address_value();
   assert(check_magic(frames_array), "invalid magic");
 }

 bool BaseFrameStream::check_magic(objArrayHandle frames_array) {
   oop   m1 = frames_array->obj_at(magic_pos);
   jlong m2 = _anchor;
   if (m1 == _thread->threadObj() && m2 == address_value())  return true;
   return false;
 }

 bool BaseFrameStream::cleanup_magic_on_exit(objArrayHandle frames_array) {
   bool ok = check_magic(frames_array);
   frames_array->obj_at_put(magic_pos, NULL);
   _anchor = 0L;
   return ok;
 }

 JavaFrameStream::JavaFrameStream(JavaThread* thread, int mode)
   : BaseFrameStream(thread), _vfst(thread) {
   _need_method_info = StackWalk::need_method_info(mode);
 }

 // Returns the BaseFrameStream for the current stack being traversed.
 //
 // Parameters:
 //  thread         Current Java thread.
 //  magic          Magic value used for each stack walking
 //  frames_array   User-supplied buffers.  The 0th element is reserved
 //                 for this BaseFrameStream to use
 //
 BaseFrameStream* BaseFrameStream::from_current(JavaThread* thread, jlong magic,
                                                objArrayHandle frames_array)
 {
   assert(thread != NULL && thread->is_Java_thread(), "");
   oop m1 = frames_array->obj_at(magic_pos);
   if (m1 != thread->threadObj())      return NULL;
   if (magic == 0L)                    return NULL;
   BaseFrameStream* stream = (BaseFrameStream*) (intptr_t) magic;
   if (!stream->is_valid_in(thread, frames_array))   return NULL;
   return stream;
 }

 // Unpacks one or more frames into user-supplied buffers.
 // Updates the end index, and returns the number of unpacked frames.
 // Always start with the existing vfst.method and bci.
 // Do not call vfst.next to advance over the last returned value.
 // In other words, do not leave any stale data in the vfst.
 //
 // Parameters:
 //   mode             Restrict which frames to be decoded.
 //   BaseFrameStream  stream of frames
 //   max_nframes      Maximum number of frames to be filled.
 //   start_index      Start index to the user-supplied buffers.
 //   frames_array     Buffer to store Class or StackFrame in, starting at start_index.
 //                    frames array is a Class<?>[] array when only getting caller
 //                    reference, and a StackFrameInfo[] array (or derivative)
 //                    otherwise. It should never be null.
 //   end_index        End index to the user-supplied buffers with unpacked frames.
 //
 // Returns the number of frames whose information was transferred into the buffers.
 //
 int StackWalk::fill_in_frames(jlong mode, BaseFrameStream& stream,
                               int max_nframes, int start_index,
                               objArrayHandle  frames_array,
                               int& end_index, TRAPS) {
   log_debug(stackwalk)("fill_in_frames limit=%d start=%d frames length=%d",
                        max_nframes, start_index, frames_array->length());
   assert(max_nframes > 0, "invalid max_nframes");
   assert(start_index + max_nframes <= frames_array->length(), "oob");

   int frames_decoded = 0;
   for (; !stream.at_end(); stream.next()) {
     Method* method = stream.method();

     if (method == NULL) continue;

     // skip hidden frames for default StackWalker option (i.e. SHOW_HIDDEN_FRAMES
     // not set) and when StackWalker::getCallerClass is called
     if (!ShowHiddenFrames && (skip_hidden_frames(mode) || get_caller_class(mode))) {
       if (method->is_hidden()) {
         if (log_is_enabled(Debug, stackwalk)) {
           ResourceMark rm(THREAD);
           outputStream* st = Log(stackwalk)::debug_stream();
           st->print("  hidden method: ");
           method->print_short_name(st);
           st->cr();
         }
         continue;
       }
     }

     int index = end_index++;
     if (log_is_enabled(Debug, stackwalk)) {
       ResourceMark rm(THREAD);
       outputStream* st = Log(stackwalk)::debug_stream();
       st->print("  %d: frame method: ", index);
       method->print_short_name(st);
       st->print_cr(" bci=%d", stream.bci());
     }

     if (!need_method_info(mode) && get_caller_class(mode) &&
           index == start_index && method->caller_sensitive()) {
       ResourceMark rm(THREAD);
       THROW_MSG_0(vmSymbols::java_lang_UnsupportedOperationException(),
         err_msg("StackWalker::getCallerClass called from @CallerSensitive %s method",
                 method->name_and_sig_as_C_string()));
     }
     // fill in StackFrameInfo and initialize MemberName
     stream.fill_frame(index, frames_array, method, CHECK_0);
     if (++frames_decoded >= max_nframes)  break;
   }
   return frames_decoded;
 }

 // Fill in the LiveStackFrameInfo at the given index in frames_array
 void LiveFrameStream::fill_frame(int index, objArrayHandle  frames_array,
                                  const methodHandle& method, TRAPS) {
   Handle stackFrame(THREAD, frames_array->obj_at(index));
   fill_live_stackframe(stackFrame, method, CHECK);
 }

 // Fill in the StackFrameInfo at the given index in frames_array
 void JavaFrameStream::fill_frame(int index, objArrayHandle  frames_array,
                                  const methodHandle& method, TRAPS) {
   if (_need_method_info) {
     Handle stackFrame(THREAD, frames_array->obj_at(index));
     fill_stackframe(stackFrame, method);
   } else {
     frames_array->obj_at_put(index, method->method_holder()->java_mirror());
   }
 }

 oop LiveFrameStream::create_primitive_value_instance(StackValueCollection* values, int i, TRAPS) {
   Klass* k = SystemDictionary::resolve_or_null(vmSymbols::java_lang_LiveStackFrameInfo(), CHECK_NULL);
   instanceKlassHandle ik (THREAD, k);

   JavaValue result(T_OBJECT);
   JavaCallArguments args;
   Symbol* signature = NULL;

   // ## TODO: type is only available in LocalVariable table, if present.
   // ## StackValue type is T_INT or T_OBJECT.
   switch (values->at(i)->type()) {
     case T_INT:
       args.push_int(values->int_at(i));
       signature = vmSymbols::asPrimitive_int_signature();
       break;

     case T_LONG:
       args.push_long(values->long_at(i));
       signature = vmSymbols::asPrimitive_long_signature();
       break;

     case T_FLOAT:
       args.push_float(values->float_at(i));
       signature = vmSymbols::asPrimitive_float_signature();
       break;

     case T_DOUBLE:
       args.push_double(values->double_at(i));
       signature = vmSymbols::asPrimitive_double_signature();
       break;

     case T_BYTE:
       args.push_int(values->int_at(i));
       signature = vmSymbols::asPrimitive_byte_signature();
       break;

     case T_SHORT:
       args.push_int(values->int_at(i));
       signature = vmSymbols::asPrimitive_short_signature();
       break;

     case T_CHAR:
       args.push_int(values->int_at(i));
       signature = vmSymbols::asPrimitive_char_signature();
       break;

     case T_BOOLEAN:
       args.push_int(values->int_at(i));
       signature = vmSymbols::asPrimitive_boolean_signature();
       break;

     case T_OBJECT:
       return values->obj_at(i)();

     case T_CONFLICT:
       // put a non-null slot
       args.push_int(0);
       signature = vmSymbols::asPrimitive_int_signature();
       break;

     default: ShouldNotReachHere();
   }
   JavaCalls::call_static(&result,
                          ik,
                          vmSymbols::asPrimitive_name(),
                          signature,
                          &args,
                          CHECK_NULL);
   return (instanceOop) result.get_jobject();
 }

 objArrayHandle LiveFrameStream::values_to_object_array(StackValueCollection* values, TRAPS) {
   objArrayHandle empty;
   int length = values->size();
   objArrayOop array_oop = oopFactory::new_objArray(SystemDictionary::Object_klass(),
                                                    length, CHECK_(empty));
   objArrayHandle array_h(THREAD, array_oop);
   for (int i = 0; i < values->size(); i++) {
     StackValue* st = values->at(i);
     oop obj = create_primitive_value_instance(values, i, CHECK_(empty));
     if (obj != NULL)
       array_h->obj_at_put(i, obj);
   }
   return array_h;
 }

 objArrayHandle LiveFrameStream::monitors_to_object_array(GrowableArray<MonitorInfo*>* monitors, TRAPS) {
   int length = monitors->length();
   objArrayOop array_oop = oopFactory::new_objArray(SystemDictionary::Object_klass(),
                                                    length, CHECK_(objArrayHandle()));
   objArrayHandle array_h(THREAD, array_oop);
   for (int i = 0; i < length; i++) {
     MonitorInfo* monitor = monitors->at(i);
     array_h->obj_at_put(i, monitor->owner());
   }
   return array_h;
 }

 // Fill StackFrameInfo with declaringClass and bci and initialize memberName
 void BaseFrameStream::fill_stackframe(Handle stackFrame, const methodHandle& method) {
   java_lang_StackFrameInfo::set_declaringClass(stackFrame(), method->method_holder()->java_mirror());
   java_lang_StackFrameInfo::set_method_and_bci(stackFrame(), method, bci());
 }

 // Fill LiveStackFrameInfo with locals, monitors, and expressions
 void LiveFrameStream::fill_live_stackframe(Handle stackFrame,
                                            const methodHandle& method, TRAPS) {
   fill_stackframe(stackFrame, method);
   if (_jvf != NULL) {
     StackValueCollection* locals = _jvf->locals();
     StackValueCollection* expressions = _jvf->expressions();
     GrowableArray<MonitorInfo*>* monitors = _jvf->monitors();

     if (!locals->is_empty()) {
       objArrayHandle locals_h = values_to_object_array(locals, CHECK);
       java_lang_LiveStackFrameInfo::set_locals(stackFrame(), locals_h());
     }
     if (!expressions->is_empty()) {
       objArrayHandle expressions_h = values_to_object_array(expressions, CHECK);
       java_lang_LiveStackFrameInfo::set_operands(stackFrame(), expressions_h());
     }
     if (monitors->length() > 0) {
       objArrayHandle monitors_h = monitors_to_object_array(monitors, CHECK);
       java_lang_LiveStackFrameInfo::set_monitors(stackFrame(), monitors_h());
     }
   }
 }

 // Begins stack walking.
 //
 // Parameters:
 //   stackStream    StackStream object
 //   mode           Stack walking mode.
 //   skip_frames    Number of frames to be skipped.
 //   frame_count    Number of frames to be traversed.
 //   start_index    Start index to the user-supplied buffers.
 //   frames_array   Buffer to store StackFrame in, starting at start_index.
 //                  frames array is a Class<?>[] array when only getting caller
 //                  reference, and a StackFrameInfo[] array (or derivative)
 //                  otherwise. It should never be null.
 //
 // Returns Object returned from AbstractStackWalker::doStackWalk call.
 //
 oop StackWalk::walk(Handle stackStream, jlong mode,
                     int skip_frames, int frame_count, int start_index,
                     objArrayHandle frames_array,
                     TRAPS) {
   ResourceMark rm(THREAD);
   JavaThread* jt = (JavaThread*)THREAD;
   log_debug(stackwalk)("Start walking: mode " JLONG_FORMAT " skip %d frames batch size %d",
                        mode, skip_frames, frame_count);

   if (frames_array.is_null()) {
     THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", NULL);
   }

   // Setup traversal onto my stack.
   if (live_frame_info(mode)) {
     assert (use_frames_array(mode), "Bad mode for get live frame");
     RegisterMap regMap(jt, true);
     LiveFrameStream stream(jt, &regMap);
     return fetchFirstBatch(stream, stackStream, mode, skip_frames, frame_count,
                            start_index, frames_array, THREAD);
   } else {
     JavaFrameStream stream(jt, mode);
     return fetchFirstBatch(stream, stackStream, mode, skip_frames, frame_count,
                            start_index, frames_array, THREAD);
   }
 }

 oop StackWalk::fetchFirstBatch(BaseFrameStream& stream, Handle stackStream,
                                jlong mode, int skip_frames, int frame_count,
                                int start_index, objArrayHandle frames_array, TRAPS) {
   methodHandle m_doStackWalk(THREAD, Universe::do_stack_walk_method());

   {
     Klass* stackWalker_klass = SystemDictionary::StackWalker_klass();
     Klass* abstractStackWalker_klass = SystemDictionary::AbstractStackWalker_klass();
     while (!stream.at_end()) {
       InstanceKlass* ik = stream.method()->method_holder();
       if (ik != stackWalker_klass &&
             ik != abstractStackWalker_klass && ik->super() != abstractStackWalker_klass)  {
         break;
       }

       if (log_is_enabled(Debug, stackwalk)) {
         ResourceMark rm(THREAD);
         outputStream* st = Log(stackwalk)::debug_stream();
         st->print("  skip ");
         stream.method()->print_short_name(st);
         st->cr();
       }
       stream.next();
     }

     // stack frame has been traversed individually and resume stack walk
     // from the stack frame at depth == skip_frames.
     for (int n=0; n < skip_frames && !stream.at_end(); stream.next(), n++) {
       if (log_is_enabled(Debug, stackwalk)) {
         ResourceMark rm(THREAD);
         outputStream* st = Log(stackwalk)::debug_stream();
         st->print("  skip ");
         stream.method()->print_short_name(st);
         st->cr();
       }
     }
   }

   int end_index = start_index;
   int numFrames = 0;
   if (!stream.at_end()) {
     numFrames = fill_in_frames(mode, stream, frame_count, start_index,
                                frames_array, end_index, CHECK_NULL);
     if (numFrames < 1) {
       THROW_MSG_(vmSymbols::java_lang_InternalError(), "stack walk: decode failed", NULL);
     }
   }

   // JVM_CallStackWalk walks the stack and fills in stack frames, then calls to
   // Java method java.lang.StackStreamFactory.AbstractStackWalker::doStackWalk
   // which calls the implementation to consume the stack frames.
   // When JVM_CallStackWalk returns, it invalidates the stack stream.
   JavaValue result(T_OBJECT);
   JavaCallArguments args(stackStream);
   args.push_long(stream.address_value());
   args.push_int(skip_frames);
   args.push_int(frame_count);
   args.push_int(start_index);
   args.push_int(end_index);

   // Link the thread and vframe stream into the callee-visible object
   stream.setup_magic_on_entry(frames_array);

   JavaCalls::call(&result, m_doStackWalk, &args, THREAD);

   // Do this before anything else happens, to disable any lingering stream objects
   bool ok = stream.cleanup_magic_on_exit(frames_array);

   // Throw pending exception if we must
   (void) (CHECK_NULL);

   if (!ok) {
     THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: corrupted buffers on exit", NULL);
   }

   // Return normally
   return (oop)result.get_jobject();
 }

 // Walk the next batch of stack frames
 //
 // Parameters:
 //   stackStream    StackStream object
 //   mode           Stack walking mode.
 //   magic          Must be valid value to continue the stack walk
 //   frame_count    Number of frames to be decoded.
 //   start_index    Start index to the user-supplied buffers.
 //   frames_array   Buffer to store StackFrame in, starting at start_index.
 //
 // Returns the end index of frame filled in the buffer.
 //
 jint StackWalk::fetchNextBatch(Handle stackStream, jlong mode, jlong magic,
                                int frame_count, int start_index,
                                objArrayHandle frames_array,
                                TRAPS)
 {
   JavaThread* jt = (JavaThread*)THREAD;
   BaseFrameStream* existing_stream = BaseFrameStream::from_current(jt, magic, frames_array);
   if (existing_stream == NULL) {
     THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: corrupted buffers", 0L);
   }

   if (frames_array.is_null()) {
     THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", 0L);
   }

   log_debug(stackwalk)("StackWalk::fetchNextBatch frame_count %d existing_stream "
                        PTR_FORMAT " start %d frames %d",
                        frame_count, p2i(existing_stream), start_index, frames_array->length());
   int end_index = start_index;
   if (frame_count <= 0) {
     return end_index;        // No operation.
   }

   int count = frame_count + start_index;
   assert (frames_array->length() >= count, "not enough space in buffers");

   BaseFrameStream& stream = (*existing_stream);
   if (!stream.at_end()) {
     stream.next(); // advance past the last frame decoded in previous batch
     if (!stream.at_end()) {
       int n = fill_in_frames(mode, stream, frame_count, start_index,
                              frames_array, end_index, CHECK_0);
       if (n < 1) {
         THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: later decode failed", 0L);
       }
       return end_index;
     }
   }
   return end_index;
 }
	/*
	* Copyright (c) 2015, 2016, 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 "classfile/javaClasses.hpp"
	#include "classfile/javaClasses.inline.hpp"
	#include "classfile/vmSymbols.hpp"
	#include "logging/log.hpp"
	#include "memory/oopFactory.hpp"
	#include "oops/oop.inline.hpp"
	#include "oops/objArrayOop.inline.hpp"
	#include "prims/stackwalk.hpp"
	#include "runtime/globals.hpp"
	#include "runtime/handles.inline.hpp"
	#include "runtime/javaCalls.hpp"
	#include "runtime/vframe.hpp"
	#include "utilities/globalDefinitions.hpp"

	// setup and cleanup actions
	void BaseFrameStream::setup_magic_on_entry(objArrayHandle frames_array) {
	frames_array->obj_at_put(magic_pos, _thread->threadObj());
	_anchor = address_value();
	assert(check_magic(frames_array), "invalid magic");
	}

	bool BaseFrameStream::check_magic(objArrayHandle frames_array) {
	oop m1 = frames_array->obj_at(magic_pos);
	jlong m2 = _anchor;
	if (m1 == _thread->threadObj() && m2 == address_value()) return true;
	return false;
	}

	bool BaseFrameStream::cleanup_magic_on_exit(objArrayHandle frames_array) {
	bool ok = check_magic(frames_array);
	frames_array->obj_at_put(magic_pos, NULL);
	_anchor = 0L;
	return ok;
	}

	JavaFrameStream::JavaFrameStream(JavaThread* thread, int mode)
	: BaseFrameStream(thread), _vfst(thread) {
	_need_method_info = StackWalk::need_method_info(mode);
	}

	// Returns the BaseFrameStream for the current stack being traversed.
	//
	// Parameters:
	// thread Current Java thread.
	// magic Magic value used for each stack walking
	// frames_array User-supplied buffers. The 0th element is reserved
	// for this BaseFrameStream to use
	//
	BaseFrameStream* BaseFrameStream::from_current(JavaThread* thread, jlong magic,
	objArrayHandle frames_array)
	{
	assert(thread != NULL && thread->is_Java_thread(), "");
	oop m1 = frames_array->obj_at(magic_pos);
	if (m1 != thread->threadObj()) return NULL;
	if (magic == 0L) return NULL;
	BaseFrameStream* stream = (BaseFrameStream*) (intptr_t) magic;
	if (!stream->is_valid_in(thread, frames_array)) return NULL;
	return stream;
	}

	// Unpacks one or more frames into user-supplied buffers.
	// Updates the end index, and returns the number of unpacked frames.
	// Always start with the existing vfst.method and bci.
	// Do not call vfst.next to advance over the last returned value.
	// In other words, do not leave any stale data in the vfst.
	//
	// Parameters:
	// mode Restrict which frames to be decoded.
	// BaseFrameStream stream of frames
	// max_nframes Maximum number of frames to be filled.
	// start_index Start index to the user-supplied buffers.
	// frames_array Buffer to store Class or StackFrame in, starting at start_index.
	// frames array is a Class<?>[] array when only getting caller
	// reference, and a StackFrameInfo[] array (or derivative)
	// otherwise. It should never be null.
	// end_index End index to the user-supplied buffers with unpacked frames.
	//
	// Returns the number of frames whose information was transferred into the buffers.
	//
	int StackWalk::fill_in_frames(jlong mode, BaseFrameStream& stream,
	int max_nframes, int start_index,
	objArrayHandle frames_array,
	int& end_index, TRAPS) {
	log_debug(stackwalk)("fill_in_frames limit=%d start=%d frames length=%d",
	max_nframes, start_index, frames_array->length());
	assert(max_nframes > 0, "invalid max_nframes");
	assert(start_index + max_nframes <= frames_array->length(), "oob");

	int frames_decoded = 0;
	for (; !stream.at_end(); stream.next()) {
	Method* method = stream.method();

	if (method == NULL) continue;

	// skip hidden frames for default StackWalker option (i.e. SHOW_HIDDEN_FRAMES
	// not set) and when StackWalker::getCallerClass is called
	if (!ShowHiddenFrames && (skip_hidden_frames(mode) \|\| get_caller_class(mode))) {
	if (method->is_hidden()) {
	if (log_is_enabled(Debug, stackwalk)) {
	ResourceMark rm(THREAD);
	outputStream* st = Log(stackwalk)::debug_stream();
	st->print(" hidden method: ");
	method->print_short_name(st);
	st->cr();
	}
	continue;
	}
	}

	int index = end_index++;
	if (log_is_enabled(Debug, stackwalk)) {
	ResourceMark rm(THREAD);
	outputStream* st = Log(stackwalk)::debug_stream();
	st->print(" %d: frame method: ", index);
	method->print_short_name(st);
	st->print_cr(" bci=%d", stream.bci());
	}

	if (!need_method_info(mode) && get_caller_class(mode) &&
	index == start_index && method->caller_sensitive()) {
	ResourceMark rm(THREAD);
	THROW_MSG_0(vmSymbols::java_lang_UnsupportedOperationException(),
	err_msg("StackWalker::getCallerClass called from @CallerSensitive %s method",
	method->name_and_sig_as_C_string()));
	}
	// fill in StackFrameInfo and initialize MemberName
	stream.fill_frame(index, frames_array, method, CHECK_0);
	if (++frames_decoded >= max_nframes) break;
	}
	return frames_decoded;
	}

	// Fill in the LiveStackFrameInfo at the given index in frames_array
	void LiveFrameStream::fill_frame(int index, objArrayHandle frames_array,
	const methodHandle& method, TRAPS) {
	Handle stackFrame(THREAD, frames_array->obj_at(index));
	fill_live_stackframe(stackFrame, method, CHECK);
	}

	// Fill in the StackFrameInfo at the given index in frames_array
	void JavaFrameStream::fill_frame(int index, objArrayHandle frames_array,
	const methodHandle& method, TRAPS) {
	if (_need_method_info) {
	Handle stackFrame(THREAD, frames_array->obj_at(index));
	fill_stackframe(stackFrame, method);
	} else {
	frames_array->obj_at_put(index, method->method_holder()->java_mirror());
	}
	}

	oop LiveFrameStream::create_primitive_value_instance(StackValueCollection* values, int i, TRAPS) {
	Klass* k = SystemDictionary::resolve_or_null(vmSymbols::java_lang_LiveStackFrameInfo(), CHECK_NULL);
	instanceKlassHandle ik (THREAD, k);

	JavaValue result(T_OBJECT);
	JavaCallArguments args;
	Symbol* signature = NULL;

	// ## TODO: type is only available in LocalVariable table, if present.
	// ## StackValue type is T_INT or T_OBJECT.
	switch (values->at(i)->type()) {
	case T_INT:
	args.push_int(values->int_at(i));
	signature = vmSymbols::asPrimitive_int_signature();
	break;

	case T_LONG:
	args.push_long(values->long_at(i));
	signature = vmSymbols::asPrimitive_long_signature();
	break;

	case T_FLOAT:
	args.push_float(values->float_at(i));
	signature = vmSymbols::asPrimitive_float_signature();
	break;

	case T_DOUBLE:
	args.push_double(values->double_at(i));
	signature = vmSymbols::asPrimitive_double_signature();
	break;

	case T_BYTE:
	args.push_int(values->int_at(i));
	signature = vmSymbols::asPrimitive_byte_signature();
	break;

	case T_SHORT:
	args.push_int(values->int_at(i));
	signature = vmSymbols::asPrimitive_short_signature();
	break;

	case T_CHAR:
	args.push_int(values->int_at(i));
	signature = vmSymbols::asPrimitive_char_signature();
	break;

	case T_BOOLEAN:
	args.push_int(values->int_at(i));
	signature = vmSymbols::asPrimitive_boolean_signature();
	break;

	case T_OBJECT:
	return values->obj_at(i)();

	case T_CONFLICT:
	// put a non-null slot
	args.push_int(0);
	signature = vmSymbols::asPrimitive_int_signature();
	break;

	default: ShouldNotReachHere();
	}
	JavaCalls::call_static(&result,
	ik,
	vmSymbols::asPrimitive_name(),
	signature,
	&args,
	CHECK_NULL);
	return (instanceOop) result.get_jobject();
	}

	objArrayHandle LiveFrameStream::values_to_object_array(StackValueCollection* values, TRAPS) {
	objArrayHandle empty;
	int length = values->size();
	objArrayOop array_oop = oopFactory::new_objArray(SystemDictionary::Object_klass(),
	length, CHECK_(empty));
	objArrayHandle array_h(THREAD, array_oop);
	for (int i = 0; i < values->size(); i++) {
	StackValue* st = values->at(i);
	oop obj = create_primitive_value_instance(values, i, CHECK_(empty));
	if (obj != NULL)
	array_h->obj_at_put(i, obj);
	}
	return array_h;
	}

	objArrayHandle LiveFrameStream::monitors_to_object_array(GrowableArray<MonitorInfo> monitors, TRAPS) {
	int length = monitors->length();
	objArrayOop array_oop = oopFactory::new_objArray(SystemDictionary::Object_klass(),
	length, CHECK_(objArrayHandle()));
	objArrayHandle array_h(THREAD, array_oop);
	for (int i = 0; i < length; i++) {
	MonitorInfo* monitor = monitors->at(i);
	array_h->obj_at_put(i, monitor->owner());
	}
	return array_h;
	}

	// Fill StackFrameInfo with declaringClass and bci and initialize memberName
	void BaseFrameStream::fill_stackframe(Handle stackFrame, const methodHandle& method) {
	java_lang_StackFrameInfo::set_declaringClass(stackFrame(), method->method_holder()->java_mirror());
	java_lang_StackFrameInfo::set_method_and_bci(stackFrame(), method, bci());
	}

	// Fill LiveStackFrameInfo with locals, monitors, and expressions
	void LiveFrameStream::fill_live_stackframe(Handle stackFrame,
	const methodHandle& method, TRAPS) {
	fill_stackframe(stackFrame, method);
	if (_jvf != NULL) {
	StackValueCollection* locals = _jvf->locals();
	StackValueCollection* expressions = _jvf->expressions();
	GrowableArray<MonitorInfo> monitors = _jvf->monitors();

	if (!locals->is_empty()) {
	objArrayHandle locals_h = values_to_object_array(locals, CHECK);
	java_lang_LiveStackFrameInfo::set_locals(stackFrame(), locals_h());
	}
	if (!expressions->is_empty()) {
	objArrayHandle expressions_h = values_to_object_array(expressions, CHECK);
	java_lang_LiveStackFrameInfo::set_operands(stackFrame(), expressions_h());
	}
	if (monitors->length() > 0) {
	objArrayHandle monitors_h = monitors_to_object_array(monitors, CHECK);
	java_lang_LiveStackFrameInfo::set_monitors(stackFrame(), monitors_h());
	}
	}
	}

	// Begins stack walking.
	//
	// Parameters:
	// stackStream StackStream object
	// mode Stack walking mode.
	// skip_frames Number of frames to be skipped.
	// frame_count Number of frames to be traversed.
	// start_index Start index to the user-supplied buffers.
	// frames_array Buffer to store StackFrame in, starting at start_index.
	// frames array is a Class<?>[] array when only getting caller
	// reference, and a StackFrameInfo[] array (or derivative)
	// otherwise. It should never be null.
	//
	// Returns Object returned from AbstractStackWalker::doStackWalk call.
	//
	oop StackWalk::walk(Handle stackStream, jlong mode,
	int skip_frames, int frame_count, int start_index,
	objArrayHandle frames_array,
	TRAPS) {
	ResourceMark rm(THREAD);
	JavaThread* jt = (JavaThread*)THREAD;
	log_debug(stackwalk)("Start walking: mode " JLONG_FORMAT " skip %d frames batch size %d",
	mode, skip_frames, frame_count);

	if (frames_array.is_null()) {
	THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", NULL);
	}

	// Setup traversal onto my stack.
	if (live_frame_info(mode)) {
	assert (use_frames_array(mode), "Bad mode for get live frame");
	RegisterMap regMap(jt, true);
	LiveFrameStream stream(jt, &regMap);
	return fetchFirstBatch(stream, stackStream, mode, skip_frames, frame_count,
	start_index, frames_array, THREAD);
	} else {
	JavaFrameStream stream(jt, mode);
	return fetchFirstBatch(stream, stackStream, mode, skip_frames, frame_count,
	start_index, frames_array, THREAD);
	}
	}

	oop StackWalk::fetchFirstBatch(BaseFrameStream& stream, Handle stackStream,
	jlong mode, int skip_frames, int frame_count,
	int start_index, objArrayHandle frames_array, TRAPS) {
	methodHandle m_doStackWalk(THREAD, Universe::do_stack_walk_method());

	{
	Klass* stackWalker_klass = SystemDictionary::StackWalker_klass();
	Klass* abstractStackWalker_klass = SystemDictionary::AbstractStackWalker_klass();
	while (!stream.at_end()) {
	InstanceKlass* ik = stream.method()->method_holder();
	if (ik != stackWalker_klass &&
	ik != abstractStackWalker_klass && ik->super() != abstractStackWalker_klass) {
	break;
	}

	if (log_is_enabled(Debug, stackwalk)) {
	ResourceMark rm(THREAD);
	outputStream* st = Log(stackwalk)::debug_stream();
	st->print(" skip ");
	stream.method()->print_short_name(st);
	st->cr();
	}
	stream.next();
	}

	// stack frame has been traversed individually and resume stack walk
	// from the stack frame at depth == skip_frames.
	for (int n=0; n < skip_frames && !stream.at_end(); stream.next(), n++) {
	if (log_is_enabled(Debug, stackwalk)) {
	ResourceMark rm(THREAD);
	outputStream* st = Log(stackwalk)::debug_stream();
	st->print(" skip ");
	stream.method()->print_short_name(st);
	st->cr();
	}
	}
	}

	int end_index = start_index;
	int numFrames = 0;
	if (!stream.at_end()) {
	numFrames = fill_in_frames(mode, stream, frame_count, start_index,
	frames_array, end_index, CHECK_NULL);
	if (numFrames < 1) {
	THROW_MSG_(vmSymbols::java_lang_InternalError(), "stack walk: decode failed", NULL);
	}
	}

	// JVM_CallStackWalk walks the stack and fills in stack frames, then calls to
	// Java method java.lang.StackStreamFactory.AbstractStackWalker::doStackWalk
	// which calls the implementation to consume the stack frames.
	// When JVM_CallStackWalk returns, it invalidates the stack stream.
	JavaValue result(T_OBJECT);
	JavaCallArguments args(stackStream);
	args.push_long(stream.address_value());
	args.push_int(skip_frames);
	args.push_int(frame_count);
	args.push_int(start_index);
	args.push_int(end_index);

	// Link the thread and vframe stream into the callee-visible object
	stream.setup_magic_on_entry(frames_array);

	JavaCalls::call(&result, m_doStackWalk, &args, THREAD);

	// Do this before anything else happens, to disable any lingering stream objects
	bool ok = stream.cleanup_magic_on_exit(frames_array);

	// Throw pending exception if we must
	(void) (CHECK_NULL);

	if (!ok) {
	THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: corrupted buffers on exit", NULL);
	}

	// Return normally
	return (oop)result.get_jobject();
	}

	// Walk the next batch of stack frames
	//
	// Parameters:
	// stackStream StackStream object
	// mode Stack walking mode.
	// magic Must be valid value to continue the stack walk
	// frame_count Number of frames to be decoded.
	// start_index Start index to the user-supplied buffers.
	// frames_array Buffer to store StackFrame in, starting at start_index.
	//
	// Returns the end index of frame filled in the buffer.
	//
	jint StackWalk::fetchNextBatch(Handle stackStream, jlong mode, jlong magic,
	int frame_count, int start_index,
	objArrayHandle frames_array,
	TRAPS)
	{
	JavaThread* jt = (JavaThread*)THREAD;
	BaseFrameStream* existing_stream = BaseFrameStream::from_current(jt, magic, frames_array);
	if (existing_stream == NULL) {
	THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: corrupted buffers", 0L);
	}

	if (frames_array.is_null()) {
	THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", 0L);
	}

	log_debug(stackwalk)("StackWalk::fetchNextBatch frame_count %d existing_stream "
	PTR_FORMAT " start %d frames %d",
	frame_count, p2i(existing_stream), start_index, frames_array->length());
	int end_index = start_index;
	if (frame_count <= 0) {
	return end_index; // No operation.
	}

	int count = frame_count + start_index;
	assert (frames_array->length() >= count, "not enough space in buffers");

	BaseFrameStream& stream = (*existing_stream);
	if (!stream.at_end()) {
	stream.next(); // advance past the last frame decoded in previous batch
	if (!stream.at_end()) {
	int n = fill_in_frames(mode, stream, frame_count, start_index,
	frames_array, end_index, CHECK_0);
	if (n < 1) {
	THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: later decode failed", 0L);
	}
	return end_index;
	}
	}
	return end_index;
	}