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hotspot/src/share/vm/prims/jvmtiImpl.cpp

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+/*
+ * Copyright 2003-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_jvmtiImpl.cpp.incl"
+
+GrowableArray<JvmtiRawMonitor*> *JvmtiPendingMonitors::_monitors = new (ResourceObj::C_HEAP) GrowableArray<JvmtiRawMonitor*>(1,true);
+
+void JvmtiPendingMonitors::transition_raw_monitors() {
+  assert((Threads::number_of_threads()==1),
+         "Java thread has not created yet or more than one java thread \
+is running. Raw monitor transition will not work");
+  JavaThread *current_java_thread = JavaThread::current();
+  assert(current_java_thread->thread_state() == _thread_in_vm, "Must be in vm");
+  {
+    ThreadBlockInVM __tbivm(current_java_thread);
+    for(int i=0; i< count(); i++) {
+      JvmtiRawMonitor *rmonitor = monitors()->at(i);
+      int r = rmonitor->raw_enter(current_java_thread);
+      assert(r == ObjectMonitor::OM_OK, "raw_enter should have worked");
+    }
+  }
+  // pending monitors are converted to real monitor so delete them all.
+  dispose();
+}
+
+//
+// class JvmtiAgentThread
+//
+// JavaThread used to wrap a thread started by an agent
+// using the JVMTI method RunAgentThread.
+//
+
+JvmtiAgentThread::JvmtiAgentThread(JvmtiEnv* env, jvmtiStartFunction start_fn, const void *start_arg)
+    : JavaThread(start_function_wrapper) {
+    _env = env;
+    _start_fn = start_fn;
+    _start_arg = start_arg;
+}
+
+void
+JvmtiAgentThread::start_function_wrapper(JavaThread *thread, TRAPS) {
+    // It is expected that any Agent threads will be created as
+    // Java Threads.  If this is the case, notification of the creation
+    // of the thread is given in JavaThread::thread_main().
+    assert(thread->is_Java_thread(), "debugger thread should be a Java Thread");
+    assert(thread == JavaThread::current(), "sanity check");
+
+    JvmtiAgentThread *dthread = (JvmtiAgentThread *)thread;
+    dthread->call_start_function();
+}
+
+void
+JvmtiAgentThread::call_start_function() {
+    ThreadToNativeFromVM transition(this);
+    _start_fn(_env->jvmti_external(), jni_environment(), (void*)_start_arg);
+}
+
+
+//
+// class GrowableCache - private methods
+//
+
+void GrowableCache::recache() {
+  int len = _elements->length();
+
+  FREE_C_HEAP_ARRAY(address, _cache);
+  _cache = NEW_C_HEAP_ARRAY(address,len+1);
+
+  for (int i=0; i<len; i++) {
+    _cache[i] = _elements->at(i)->getCacheValue();
+    //
+    // The cache entry has gone bad. Without a valid frame pointer
+    // value, the entry is useless so we simply delete it in product
+    // mode. The call to remove() will rebuild the cache again
+    // without the bad entry.
+    //
+    if (_cache[i] == NULL) {
+      assert(false, "cannot recache NULL elements");
+      remove(i);
+      return;
+    }
+  }
+  _cache[len] = NULL;
+
+  _listener_fun(_this_obj,_cache);
+}
+
+bool GrowableCache::equals(void* v, GrowableElement *e2) {
+  GrowableElement *e1 = (GrowableElement *) v;
+  assert(e1 != NULL, "e1 != NULL");
+  assert(e2 != NULL, "e2 != NULL");
+
+  return e1->equals(e2);
+}
+
+//
+// class GrowableCache - public methods
+//
+
+GrowableCache::GrowableCache() {
+  _this_obj       = NULL;
+  _listener_fun   = NULL;
+  _elements       = NULL;
+  _cache          = NULL;
+}
+
+GrowableCache::~GrowableCache() {
+  clear();
+  delete _elements;
+  FREE_C_HEAP_ARRAY(address, _cache);
+}
+
+void GrowableCache::initialize(void *this_obj, void listener_fun(void *, address*) ) {
+  _this_obj       = this_obj;
+  _listener_fun   = listener_fun;
+  _elements       = new (ResourceObj::C_HEAP) GrowableArray<GrowableElement*>(5,true);
+  recache();
+}
+
+// number of elements in the collection
+int GrowableCache::length() {
+  return _elements->length();
+}
+
+// get the value of the index element in the collection
+GrowableElement* GrowableCache::at(int index) {
+  GrowableElement *e = (GrowableElement *) _elements->at(index);
+  assert(e != NULL, "e != NULL");
+  return e;
+}
+
+int GrowableCache::find(GrowableElement* e) {
+  return _elements->find(e, GrowableCache::equals);
+}
+
+// append a copy of the element to the end of the collection
+void GrowableCache::append(GrowableElement* e) {
+  GrowableElement *new_e = e->clone();
+  _elements->append(new_e);
+  recache();
+}
+
+// insert a copy of the element using lessthan()
+void GrowableCache::insert(GrowableElement* e) {
+  GrowableElement *new_e = e->clone();
+  _elements->append(new_e);
+
+  int n = length()-2;
+  for (int i=n; i>=0; i--) {
+    GrowableElement *e1 = _elements->at(i);
+    GrowableElement *e2 = _elements->at(i+1);
+    if (e2->lessThan(e1)) {
+      _elements->at_put(i+1, e1);
+      _elements->at_put(i,   e2);
+    }
+  }
+
+  recache();
+}
+
+// remove the element at index
+void GrowableCache::remove (int index) {
+  GrowableElement *e = _elements->at(index);
+  assert(e != NULL, "e != NULL");
+  _elements->remove(e);
+  delete e;
+  recache();
+}
+
+// clear out all elements, release all heap space and
+// let our listener know that things have changed.
+void GrowableCache::clear() {
+  int len = _elements->length();
+  for (int i=0; i<len; i++) {
+    delete _elements->at(i);
+  }
+  _elements->clear();
+  recache();
+}
+
+void GrowableCache::oops_do(OopClosure* f) {
+  int len = _elements->length();
+  for (int i=0; i<len; i++) {
+    GrowableElement *e = _elements->at(i);
+    e->oops_do(f);
+  }
+}
+
+void GrowableCache::gc_epilogue() {
+  int len = _elements->length();
+  // recompute the new cache value after GC
+  for (int i=0; i<len; i++) {
+    _cache[i] = _elements->at(i)->getCacheValue();
+  }
+}
+
+
+//
+// class JvmtiRawMonitor
+//
+
+JvmtiRawMonitor::JvmtiRawMonitor(const char *name) {
+#ifdef ASSERT
+  _name = strcpy(NEW_C_HEAP_ARRAY(char, strlen(name) + 1), name);
+#else
+  _name = NULL;
+#endif
+  _magic = JVMTI_RM_MAGIC;
+}
+
+JvmtiRawMonitor::~JvmtiRawMonitor() {
+#ifdef ASSERT
+  FreeHeap(_name);
+#endif
+  _magic = 0;
+}
+
+
+//
+// class JvmtiBreakpoint
+//
+
+JvmtiBreakpoint::JvmtiBreakpoint() {
+  _method = NULL;
+  _bci    = 0;
+#ifdef CHECK_UNHANDLED_OOPS
+  // This one is always allocated with new, but check it just in case.
+  Thread *thread = Thread::current();
+  if (thread->is_in_stack((address)&_method)) {
+    thread->allow_unhandled_oop((oop*)&_method);
+  }
+#endif // CHECK_UNHANDLED_OOPS
+}
+
+JvmtiBreakpoint::JvmtiBreakpoint(methodOop m_method, jlocation location) {
+  _method        = m_method;
+  assert(_method != NULL, "_method != NULL");
+  _bci           = (int) location;
+#ifdef CHECK_UNHANDLED_OOPS
+  // Could be allocated with new and wouldn't be on the unhandled oop list.
+  Thread *thread = Thread::current();
+  if (thread->is_in_stack((address)&_method)) {
+    thread->allow_unhandled_oop(&_method);
+  }
+#endif // CHECK_UNHANDLED_OOPS
+
+  assert(_bci >= 0, "_bci >= 0");
+}
+
+void JvmtiBreakpoint::copy(JvmtiBreakpoint& bp) {
+  _method   = bp._method;
+  _bci      = bp._bci;
+}
+
+bool JvmtiBreakpoint::lessThan(JvmtiBreakpoint& bp) {
+  Unimplemented();
+  return false;
+}
+
+bool JvmtiBreakpoint::equals(JvmtiBreakpoint& bp) {
+  return _method   == bp._method
+    &&   _bci      == bp._bci;
+}
+
+bool JvmtiBreakpoint::is_valid() {
+  return _method != NULL &&
+         _bci >= 0;
+}
+
+address JvmtiBreakpoint::getBcp() {
+  return _method->bcp_from(_bci);
+}
+
+void JvmtiBreakpoint::each_method_version_do(method_action meth_act) {
+  ((methodOopDesc*)_method->*meth_act)(_bci);
+
+  // add/remove breakpoint to/from versions of the method that
+  // are EMCP. Directly or transitively obsolete methods are
+  // not saved in the PreviousVersionInfo.
+  Thread *thread = Thread::current();
+  instanceKlassHandle ikh = instanceKlassHandle(thread, _method->method_holder());
+  symbolOop m_name = _method->name();
+  symbolOop m_signature = _method->signature();
+
+  {
+    ResourceMark rm(thread);
+    // PreviousVersionInfo objects returned via PreviousVersionWalker
+    // contain a GrowableArray of handles. We have to clean up the
+    // GrowableArray _after_ the PreviousVersionWalker destructor
+    // has destroyed the handles.
+    {
+      // search previous versions if they exist
+      PreviousVersionWalker pvw((instanceKlass *)ikh()->klass_part());
+      for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
+           pv_info != NULL; pv_info = pvw.next_previous_version()) {
+        GrowableArray<methodHandle>* methods =
+          pv_info->prev_EMCP_method_handles();
+
+        if (methods == NULL) {
+          // We have run into a PreviousVersion generation where
+          // all methods were made obsolete during that generation's
+          // RedefineClasses() operation. At the time of that
+          // operation, all EMCP methods were flushed so we don't
+          // have to go back any further.
+          //
+          // A NULL methods array is different than an empty methods
+          // array. We cannot infer any optimizations about older
+          // generations from an empty methods array for the current
+          // generation.
+          break;
+        }
+
+        for (int i = methods->length() - 1; i >= 0; i--) {
+          methodHandle method = methods->at(i);
+          if (method->name() == m_name && method->signature() == m_signature) {
+            RC_TRACE(0x00000800, ("%sing breakpoint in %s(%s)",
+              meth_act == &methodOopDesc::set_breakpoint ? "sett" : "clear",
+              method->name()->as_C_string(),
+              method->signature()->as_C_string()));
+            assert(!method->is_obsolete(), "only EMCP methods here");
+
+            ((methodOopDesc*)method()->*meth_act)(_bci);
+            break;
+          }
+        }
+      }
+    } // pvw is cleaned up
+  } // rm is cleaned up
+}
+
+void JvmtiBreakpoint::set() {
+  each_method_version_do(&methodOopDesc::set_breakpoint);
+}
+
+void JvmtiBreakpoint::clear() {
+  each_method_version_do(&methodOopDesc::clear_breakpoint);
+}
+
+void JvmtiBreakpoint::print() {
+#ifndef PRODUCT
+  const char *class_name  = (_method == NULL) ? "NULL" : _method->klass_name()->as_C_string();
+  const char *method_name = (_method == NULL) ? "NULL" : _method->name()->as_C_string();
+
+  tty->print("Breakpoint(%s,%s,%d,%p)",class_name, method_name, _bci, getBcp());
+#endif
+}
+
+
+//
+// class VM_ChangeBreakpoints
+//
+// Modify the Breakpoints data structure at a safepoint
+//
+
+void VM_ChangeBreakpoints::doit() {
+  switch (_operation) {
+  case SET_BREAKPOINT:
+    _breakpoints->set_at_safepoint(*_bp);
+    break;
+  case CLEAR_BREAKPOINT:
+    _breakpoints->clear_at_safepoint(*_bp);
+    break;
+  case CLEAR_ALL_BREAKPOINT:
+    _breakpoints->clearall_at_safepoint();
+    break;
+  default:
+    assert(false, "Unknown operation");
+  }
+}
+
+void VM_ChangeBreakpoints::oops_do(OopClosure* f) {
+  // This operation keeps breakpoints alive
+  if (_breakpoints != NULL) {
+    _breakpoints->oops_do(f);
+  }
+  if (_bp != NULL) {
+    _bp->oops_do(f);
+  }
+}
+
+//
+// class JvmtiBreakpoints
+//
+// a JVMTI internal collection of JvmtiBreakpoint
+//
+
+JvmtiBreakpoints::JvmtiBreakpoints(void listener_fun(void *,address *)) {
+  _bps.initialize(this,listener_fun);
+}
+
+JvmtiBreakpoints:: ~JvmtiBreakpoints() {}
+
+void  JvmtiBreakpoints::oops_do(OopClosure* f) {
+  _bps.oops_do(f);
+}
+
+void  JvmtiBreakpoints::gc_epilogue() {
+  _bps.gc_epilogue();
+}
+
+void  JvmtiBreakpoints::print() {
+#ifndef PRODUCT
+  ResourceMark rm;
+
+  int n = _bps.length();
+  for (int i=0; i<n; i++) {
+    JvmtiBreakpoint& bp = _bps.at(i);
+    tty->print("%d: ", i);
+    bp.print();
+    tty->print_cr("");
+  }
+#endif
+}
+
+
+void JvmtiBreakpoints::set_at_safepoint(JvmtiBreakpoint& bp) {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+
+  int i = _bps.find(bp);
+  if (i == -1) {
+    _bps.append(bp);
+    bp.set();
+  }
+}
+
+void JvmtiBreakpoints::clear_at_safepoint(JvmtiBreakpoint& bp) {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+
+  int i = _bps.find(bp);
+  if (i != -1) {
+    _bps.remove(i);
+    bp.clear();
+  }
+}
+
+void JvmtiBreakpoints::clearall_at_safepoint() {
+  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+
+  int len = _bps.length();
+  for (int i=0; i<len; i++) {
+    _bps.at(i).clear();
+  }
+  _bps.clear();
+}
+
+int JvmtiBreakpoints::length() { return _bps.length(); }
+
+int JvmtiBreakpoints::set(JvmtiBreakpoint& bp) {
+  if ( _bps.find(bp) != -1) {
+     return JVMTI_ERROR_DUPLICATE;
+  }
+  VM_ChangeBreakpoints set_breakpoint(this,VM_ChangeBreakpoints::SET_BREAKPOINT, &bp);
+  VMThread::execute(&set_breakpoint);
+  return JVMTI_ERROR_NONE;
+}
+
+int JvmtiBreakpoints::clear(JvmtiBreakpoint& bp) {
+  if ( _bps.find(bp) == -1) {
+     return JVMTI_ERROR_NOT_FOUND;
+  }
+
+  VM_ChangeBreakpoints clear_breakpoint(this,VM_ChangeBreakpoints::CLEAR_BREAKPOINT, &bp);
+  VMThread::execute(&clear_breakpoint);
+  return JVMTI_ERROR_NONE;
+}
+
+void JvmtiBreakpoints::clearall_in_class_at_safepoint(klassOop klass) {
+  bool changed = true;
+  // We are going to run thru the list of bkpts
+  // and delete some.  This deletion probably alters
+  // the list in some implementation defined way such
+  // that when we delete entry i, the next entry might
+  // no longer be at i+1.  To be safe, each time we delete
+  // an entry, we'll just start again from the beginning.
+  // We'll stop when we make a pass thru the whole list without
+  // deleting anything.
+  while (changed) {
+    int len = _bps.length();
+    changed = false;
+    for (int i = 0; i < len; i++) {
+      JvmtiBreakpoint& bp = _bps.at(i);
+      if (bp.method()->method_holder() == klass) {
+        bp.clear();
+        _bps.remove(i);
+        // This changed 'i' so we have to start over.
+        changed = true;
+        break;
+      }
+    }
+  }
+}
+
+void JvmtiBreakpoints::clearall() {
+  VM_ChangeBreakpoints clearall_breakpoint(this,VM_ChangeBreakpoints::CLEAR_ALL_BREAKPOINT);
+  VMThread::execute(&clearall_breakpoint);
+}
+
+//
+// class JvmtiCurrentBreakpoints
+//
+
+JvmtiBreakpoints *JvmtiCurrentBreakpoints::_jvmti_breakpoints  = NULL;
+address *         JvmtiCurrentBreakpoints::_breakpoint_list    = NULL;
+
+
+JvmtiBreakpoints& JvmtiCurrentBreakpoints::get_jvmti_breakpoints() {
+  if (_jvmti_breakpoints != NULL) return (*_jvmti_breakpoints);
+  _jvmti_breakpoints = new JvmtiBreakpoints(listener_fun);
+  assert(_jvmti_breakpoints != NULL, "_jvmti_breakpoints != NULL");
+  return (*_jvmti_breakpoints);
+}
+
+void  JvmtiCurrentBreakpoints::listener_fun(void *this_obj, address *cache) {
+  JvmtiBreakpoints *this_jvmti = (JvmtiBreakpoints *) this_obj;
+  assert(this_jvmti != NULL, "this_jvmti != NULL");
+
+  debug_only(int n = this_jvmti->length(););
+  assert(cache[n] == NULL, "cache must be NULL terminated");
+
+  set_breakpoint_list(cache);
+}
+
+
+void JvmtiCurrentBreakpoints::oops_do(OopClosure* f) {
+  if (_jvmti_breakpoints != NULL) {
+    _jvmti_breakpoints->oops_do(f);
+  }
+}
+
+void JvmtiCurrentBreakpoints::gc_epilogue() {
+  if (_jvmti_breakpoints != NULL) {
+    _jvmti_breakpoints->gc_epilogue();
+  }
+}
+
+
+///////////////////////////////////////////////////////////////
+//
+// class VM_GetOrSetLocal
+//
+
+// Constructor for non-object getter
+VM_GetOrSetLocal::VM_GetOrSetLocal(JavaThread* thread, jint depth, int index, BasicType type)
+  : _thread(thread)
+  , _calling_thread(NULL)
+  , _depth(depth)
+  , _index(index)
+  , _type(type)
+  , _set(false)
+  , _jvf(NULL)
+  , _result(JVMTI_ERROR_NONE)
+{
+}
+
+// Constructor for object or non-object setter
+VM_GetOrSetLocal::VM_GetOrSetLocal(JavaThread* thread, jint depth, int index, BasicType type, jvalue value)
+  : _thread(thread)
+  , _calling_thread(NULL)
+  , _depth(depth)
+  , _index(index)
+  , _type(type)
+  , _value(value)
+  , _set(true)
+  , _jvf(NULL)
+  , _result(JVMTI_ERROR_NONE)
+{
+}
+
+// Constructor for object getter
+VM_GetOrSetLocal::VM_GetOrSetLocal(JavaThread* thread, JavaThread* calling_thread, jint depth, int index)
+  : _thread(thread)
+  , _calling_thread(calling_thread)
+  , _depth(depth)
+  , _index(index)
+  , _type(T_OBJECT)
+  , _set(false)
+  , _jvf(NULL)
+  , _result(JVMTI_ERROR_NONE)
+{
+}
+
+
+vframe *VM_GetOrSetLocal::get_vframe() {
+  if (!_thread->has_last_Java_frame()) {
+    return NULL;
+  }
+  RegisterMap reg_map(_thread);
+  vframe *vf = _thread->last_java_vframe(&reg_map);
+  int d = 0;
+  while ((vf != NULL) && (d < _depth)) {
+    vf = vf->java_sender();
+    d++;
+  }
+  return vf;
+}
+
+javaVFrame *VM_GetOrSetLocal::get_java_vframe() {
+  vframe* vf = get_vframe();
+  if (vf == NULL) {
+    _result = JVMTI_ERROR_NO_MORE_FRAMES;
+    return NULL;
+  }
+  javaVFrame *jvf = (javaVFrame*)vf;
+
+  if (!vf->is_java_frame() || jvf->method()->is_native()) {
+    _result = JVMTI_ERROR_OPAQUE_FRAME;
+    return NULL;
+  }
+  return jvf;
+}
+
+// Check that the klass is assignable to a type with the given signature.
+// Another solution could be to use the function Klass::is_subtype_of(type).
+// But the type class can be forced to load/initialize eagerly in such a case.
+// This may cause unexpected consequences like CFLH or class-init JVMTI events.
+// It is better to avoid such a behavior.
+bool VM_GetOrSetLocal::is_assignable(const char* ty_sign, Klass* klass, Thread* thread) {
+  assert(ty_sign != NULL, "type signature must not be NULL");
+  assert(thread != NULL, "thread must not be NULL");
+  assert(klass != NULL, "klass must not be NULL");
+
+  int len = (int) strlen(ty_sign);
+  if (ty_sign[0] == 'L' && ty_sign[len-1] == ';') { // Need pure class/interface name
+    ty_sign++;
+    len -= 2;
+  }
+  symbolHandle ty_sym = oopFactory::new_symbol_handle(ty_sign, len, thread);
+  if (klass->name() == ty_sym()) {
+    return true;
+  }
+  // Compare primary supers
+  int super_depth = klass->super_depth();
+  int idx;
+  for (idx = 0; idx < super_depth; idx++) {
+    if (Klass::cast(klass->primary_super_of_depth(idx))->name() == ty_sym()) {
+      return true;
+    }
+  }
+  // Compare secondary supers
+  objArrayOop sec_supers = klass->secondary_supers();
+  for (idx = 0; idx < sec_supers->length(); idx++) {
+    if (Klass::cast((klassOop) sec_supers->obj_at(idx))->name() == ty_sym()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// Checks error conditions:
+//   JVMTI_ERROR_INVALID_SLOT
+//   JVMTI_ERROR_TYPE_MISMATCH
+// Returns: 'true' - everything is Ok, 'false' - error code
+
+bool VM_GetOrSetLocal::check_slot_type(javaVFrame* jvf) {
+  methodOop method_oop = jvf->method();
+  if (!method_oop->has_localvariable_table()) {
+    // Just to check index boundaries
+    jint extra_slot = (_type == T_LONG || _type == T_DOUBLE) ? 1 : 0;
+    if (_index < 0 || _index + extra_slot >= method_oop->max_locals()) {
+      _result = JVMTI_ERROR_INVALID_SLOT;
+      return false;
+    }
+    return true;
+  }
+
+  jint num_entries = method_oop->localvariable_table_length();
+  if (num_entries == 0) {
+    _result = JVMTI_ERROR_INVALID_SLOT;
+    return false;       // There are no slots
+  }
+  int signature_idx = -1;
+  int vf_bci = jvf->bci();
+  LocalVariableTableElement* table = method_oop->localvariable_table_start();
+  for (int i = 0; i < num_entries; i++) {
+    int start_bci = table[i].start_bci;
+    int end_bci = start_bci + table[i].length;
+
+    // Here we assume that locations of LVT entries
+    // with the same slot number cannot be overlapped
+    if (_index == (jint) table[i].slot && start_bci <= vf_bci && vf_bci <= end_bci) {
+      signature_idx = (int) table[i].descriptor_cp_index;
+      break;
+    }
+  }
+  if (signature_idx == -1) {
+    _result = JVMTI_ERROR_INVALID_SLOT;
+    return false;       // Incorrect slot index
+  }
+  symbolOop   sign_sym  = method_oop->constants()->symbol_at(signature_idx);
+  const char* signature = (const char *) sign_sym->as_utf8();
+  BasicType slot_type = char2type(signature[0]);
+
+  switch (slot_type) {
+  case T_BYTE:
+  case T_SHORT:
+  case T_CHAR:
+  case T_BOOLEAN:
+    slot_type = T_INT;
+    break;
+  case T_ARRAY:
+    slot_type = T_OBJECT;
+    break;
+  };
+  if (_type != slot_type) {
+    _result = JVMTI_ERROR_TYPE_MISMATCH;
+    return false;
+  }
+
+  jobject jobj = _value.l;
+  if (_set && slot_type == T_OBJECT && jobj != NULL) { // NULL reference is allowed
+    // Check that the jobject class matches the return type signature.
+    JavaThread* cur_thread = JavaThread::current();
+    HandleMark hm(cur_thread);
+
+    Handle obj = Handle(cur_thread, JNIHandles::resolve_external_guard(jobj));
+    NULL_CHECK(obj, (_result = JVMTI_ERROR_INVALID_OBJECT, false));
+    KlassHandle ob_kh = KlassHandle(cur_thread, obj->klass());
+    NULL_CHECK(ob_kh, (_result = JVMTI_ERROR_INVALID_OBJECT, false));
+
+    if (!is_assignable(signature, Klass::cast(ob_kh()), cur_thread)) {
+      _result = JVMTI_ERROR_TYPE_MISMATCH;
+      return false;
+    }
+  }
+  return true;
+}
+
+static bool can_be_deoptimized(vframe* vf) {
+  return (vf->is_compiled_frame() && vf->fr().can_be_deoptimized());
+}
+
+bool VM_GetOrSetLocal::doit_prologue() {
+  _jvf = get_java_vframe();
+  NULL_CHECK(_jvf, false);
+
+  if (!check_slot_type(_jvf)) {
+    return false;
+  }
+  return true;
+}
+
+void VM_GetOrSetLocal::doit() {
+  if (_set) {
+    // Force deoptimization of frame if compiled because it's
+    // possible the compiler emitted some locals as constant values,
+    // meaning they are not mutable.
+    if (can_be_deoptimized(_jvf)) {
+
+      // Schedule deoptimization so that eventually the local
+      // update will be written to an interpreter frame.
+      VM_DeoptimizeFrame deopt(_jvf->thread(), _jvf->fr().id());
+      VMThread::execute(&deopt);
+
+      // Now store a new value for the local which will be applied
+      // once deoptimization occurs. Note however that while this
+      // write is deferred until deoptimization actually happens
+      // can vframe created after this point will have its locals
+      // reflecting this update so as far as anyone can see the
+      // write has already taken place.
+
+      // If we are updating an oop then get the oop from the handle
+      // since the handle will be long gone by the time the deopt
+      // happens. The oop stored in the deferred local will be
+      // gc'd on its own.
+      if (_type == T_OBJECT) {
+        _value.l = (jobject) (JNIHandles::resolve_external_guard(_value.l));
+      }
+      // Re-read the vframe so we can see that it is deoptimized
+      // [ Only need because of assert in update_local() ]
+      _jvf = get_java_vframe();
+      ((compiledVFrame*)_jvf)->update_local(_type, _index, _value);
+      return;
+    }
+    StackValueCollection *locals = _jvf->locals();
+    HandleMark hm;
+
+    switch (_type) {
+    case T_INT:    locals->set_int_at   (_index, _value.i); break;
+    case T_LONG:   locals->set_long_at  (_index, _value.j); break;
+    case T_FLOAT:  locals->set_float_at (_index, _value.f); break;
+    case T_DOUBLE: locals->set_double_at(_index, _value.d); break;
+    case T_OBJECT: {
+      Handle ob_h(JNIHandles::resolve_external_guard(_value.l));
+      locals->set_obj_at (_index, ob_h);
+      break;
+    }
+    default: ShouldNotReachHere();
+    }
+    _jvf->set_locals(locals);
+  } else {
+    StackValueCollection *locals = _jvf->locals();
+
+    if (locals->at(_index)->type() == T_CONFLICT) {
+      memset(&_value, 0, sizeof(_value));
+      _value.l = NULL;
+      return;
+    }
+
+    switch (_type) {
+    case T_INT:    _value.i = locals->int_at   (_index);   break;
+    case T_LONG:   _value.j = locals->long_at  (_index);   break;
+    case T_FLOAT:  _value.f = locals->float_at (_index);   break;
+    case T_DOUBLE: _value.d = locals->double_at(_index);   break;
+    case T_OBJECT: {
+      // Wrap the oop to be returned in a local JNI handle since
+      // oops_do() no longer applies after doit() is finished.
+      oop obj = locals->obj_at(_index)();
+      _value.l = JNIHandles::make_local(_calling_thread, obj);
+      break;
+    }
+    default: ShouldNotReachHere();
+    }
+  }
+}
+
+
+bool VM_GetOrSetLocal::allow_nested_vm_operations() const {
+  return true; // May need to deoptimize
+}
+
+
+/////////////////////////////////////////////////////////////////////////////////////////
+
+//
+// class JvmtiSuspendControl - see comments in jvmtiImpl.hpp
+//
+
+bool JvmtiSuspendControl::suspend(JavaThread *java_thread) {
+  // external suspend should have caught suspending a thread twice
+
+  // Immediate suspension required for JPDA back-end so JVMTI agent threads do
+  // not deadlock due to later suspension on transitions while holding
+  // raw monitors.  Passing true causes the immediate suspension.
+  // java_suspend() will catch threads in the process of exiting
+  // and will ignore them.
+  java_thread->java_suspend();
+
+  // It would be nice to have the following assertion in all the time,
+  // but it is possible for a racing resume request to have resumed
+  // this thread right after we suspended it. Temporarily enable this
+  // assertion if you are chasing a different kind of bug.
+  //
+  // assert(java_lang_Thread::thread(java_thread->threadObj()) == NULL ||
+  //   java_thread->is_being_ext_suspended(), "thread is not suspended");
+
+  if (java_lang_Thread::thread(java_thread->threadObj()) == NULL) {
+    // check again because we can get delayed in java_suspend():
+    // the thread is in process of exiting.
+    return false;
+  }
+
+  return true;
+}
+
+bool JvmtiSuspendControl::resume(JavaThread *java_thread) {
+  // external suspend should have caught resuming a thread twice
+  assert(java_thread->is_being_ext_suspended(), "thread should be suspended");
+
+  // resume thread
+  {
+    // must always grab Threads_lock, see JVM_SuspendThread
+    MutexLocker ml(Threads_lock);
+    java_thread->java_resume();
+  }
+
+  return true;
+}
+
+
+void JvmtiSuspendControl::print() {
+#ifndef PRODUCT
+  MutexLocker mu(Threads_lock);
+  ResourceMark rm;
+
+  tty->print("Suspended Threads: [");
+  for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->next()) {
+#if JVMTI_TRACE
+    const char *name   = JvmtiTrace::safe_get_thread_name(thread);
+#else
+    const char *name   = "";
+#endif /*JVMTI_TRACE */
+    tty->print("%s(%c ", name, thread->is_being_ext_suspended() ? 'S' : '_');
+    if (!thread->has_last_Java_frame()) {
+      tty->print("no stack");
+    }
+    tty->print(") ");
+  }
+  tty->print_cr("]");
+#endif
+}