deoptimization.cpp

/*
 * Copyright 1997-2007 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/_deoptimization.cpp.incl"

bool DeoptimizationMarker::_is_active = false;

Deoptimization::UnrollBlock::UnrollBlock(int  size_of_deoptimized_frame,
                                         int  caller_adjustment,
                                         int  number_of_frames,
                                         intptr_t* frame_sizes,
                                         address* frame_pcs,
                                         BasicType return_type) {
  _size_of_deoptimized_frame = size_of_deoptimized_frame;
  _caller_adjustment         = caller_adjustment;
  _number_of_frames          = number_of_frames;
  _frame_sizes               = frame_sizes;
  _frame_pcs                 = frame_pcs;
  _register_block            = NEW_C_HEAP_ARRAY(intptr_t, RegisterMap::reg_count * 2);
  _return_type               = return_type;
  // PD (x86 only)
  _counter_temp              = 0;
  _initial_fp                = 0;
  _unpack_kind               = 0;
  _sender_sp_temp            = 0;

  _total_frame_sizes         = size_of_frames();
}


Deoptimization::UnrollBlock::~UnrollBlock() {
  FREE_C_HEAP_ARRAY(intptr_t, _frame_sizes);
  FREE_C_HEAP_ARRAY(intptr_t, _frame_pcs);
  FREE_C_HEAP_ARRAY(intptr_t, _register_block);
}


intptr_t* Deoptimization::UnrollBlock::value_addr_at(int register_number) const {
  assert(register_number < RegisterMap::reg_count, "checking register number");
  return &_register_block[register_number * 2];
}



int Deoptimization::UnrollBlock::size_of_frames() const {
  // Acount first for the adjustment of the initial frame
  int result = _caller_adjustment;
  for (int index = 0; index < number_of_frames(); index++) {
    result += frame_sizes()[index];
  }
  return result;
}


void Deoptimization::UnrollBlock::print() {
  ttyLocker ttyl;
  tty->print_cr("UnrollBlock");
  tty->print_cr("  size_of_deoptimized_frame = %d", _size_of_deoptimized_frame);
  tty->print(   "  frame_sizes: ");
  for (int index = 0; index < number_of_frames(); index++) {
    tty->print("%d ", frame_sizes()[index]);
  }
  tty->cr();
}


// In order to make fetch_unroll_info work properly with escape
// analysis, The method was changed from JRT_LEAF to JRT_BLOCK_ENTRY and
// ResetNoHandleMark and HandleMark were removed from it. The actual reallocation
// of previously eliminated objects occurs in realloc_objects, which is
// called from the method fetch_unroll_info_helper below.
JRT_BLOCK_ENTRY(Deoptimization::UnrollBlock*, Deoptimization::fetch_unroll_info(JavaThread* thread))
  // It is actually ok to allocate handles in a leaf method. It causes no safepoints,
  // but makes the entry a little slower. There is however a little dance we have to
  // do in debug mode to get around the NoHandleMark code in the JRT_LEAF macro

  // fetch_unroll_info() is called at the beginning of the deoptimization
  // handler. Note this fact before we start generating temporary frames
  // that can confuse an asynchronous stack walker. This counter is
  // decremented at the end of unpack_frames().
  thread->inc_in_deopt_handler();

  return fetch_unroll_info_helper(thread);
JRT_END


// This is factored, since it is both called from a JRT_LEAF (deoptimization) and a JRT_ENTRY (uncommon_trap)
Deoptimization::UnrollBlock* Deoptimization::fetch_unroll_info_helper(JavaThread* thread) {

  // Note: there is a safepoint safety issue here. No matter whether we enter
  // via vanilla deopt or uncommon trap we MUST NOT stop at a safepoint once
  // the vframeArray is created.
  //

  // Allocate our special deoptimization ResourceMark
  DeoptResourceMark* dmark = new DeoptResourceMark(thread);
  assert(thread->deopt_mark() == NULL, "Pending deopt!");
  thread->set_deopt_mark(dmark);

  frame stub_frame = thread->last_frame(); // Makes stack walkable as side effect
  RegisterMap map(thread, true);
  RegisterMap dummy_map(thread, false);
  // Now get the deoptee with a valid map
  frame deoptee = stub_frame.sender(&map);

  // Create a growable array of VFrames where each VFrame represents an inlined
  // Java frame.  This storage is allocated with the usual system arena.
  assert(deoptee.is_compiled_frame(), "Wrong frame type");
  GrowableArray<compiledVFrame*>* chunk = new GrowableArray<compiledVFrame*>(10);
  vframe* vf = vframe::new_vframe(&deoptee, &map, thread);
  while (!vf->is_top()) {
    assert(vf->is_compiled_frame(), "Wrong frame type");
    chunk->push(compiledVFrame::cast(vf));
    vf = vf->sender();
  }
  assert(vf->is_compiled_frame(), "Wrong frame type");
  chunk->push(compiledVFrame::cast(vf));

#ifdef COMPILER2
  // Reallocate the non-escaping objects and restore their fields. Then
  // relock objects if synchronization on them was eliminated.
  if (DoEscapeAnalysis && EliminateAllocations) {
    GrowableArray<ScopeValue*>* objects = chunk->at(0)->scope()->objects();
    bool reallocated = false;
    if (objects != NULL) {
      JRT_BLOCK
        reallocated = realloc_objects(thread, &deoptee, objects, THREAD);
      JRT_END
    }
    if (reallocated) {
      reassign_fields(&deoptee, &map, objects);
#ifndef PRODUCT
      if (TraceDeoptimization) {
        ttyLocker ttyl;
        tty->print_cr("REALLOC OBJECTS in thread " INTPTR_FORMAT, thread);
        print_objects(objects);
      }
#endif
    }
    for (int i = 0; i < chunk->length(); i++) {
      GrowableArray<MonitorValue*>* monitors = chunk->at(i)->scope()->monitors();
      if (monitors != NULL) {
        relock_objects(&deoptee, &map, monitors);
#ifndef PRODUCT
        if (TraceDeoptimization) {
          ttyLocker ttyl;
          tty->print_cr("RELOCK OBJECTS in thread " INTPTR_FORMAT, thread);
          for (int j = 0; i < monitors->length(); i++) {
            MonitorValue* mv = monitors->at(i);
            if (mv->eliminated()) {
              StackValue* owner = StackValue::create_stack_value(&deoptee, &map, mv->owner());
              tty->print_cr("     object <" INTPTR_FORMAT "> locked", owner->get_obj()());
            }
          }
        }
#endif
      }
    }
  }
#endif // COMPILER2
  // Ensure that no safepoint is taken after pointers have been stored
  // in fields of rematerialized objects.  If a safepoint occurs from here on
  // out the java state residing in the vframeArray will be missed.
  No_Safepoint_Verifier no_safepoint;

  vframeArray* array = create_vframeArray(thread, deoptee, &map, chunk);

  assert(thread->vframe_array_head() == NULL, "Pending deopt!");;
  thread->set_vframe_array_head(array);

  // Now that the vframeArray has been created if we have any deferred local writes
  // added by jvmti then we can free up that structure as the data is now in the
  // vframeArray

  if (thread->deferred_locals() != NULL) {
    GrowableArray<jvmtiDeferredLocalVariableSet*>* list = thread->deferred_locals();
    int i = 0;
    do {
      // Because of inlining we could have multiple vframes for a single frame
      // and several of the vframes could have deferred writes. Find them all.
      if (list->at(i)->id() == array->original().id()) {
        jvmtiDeferredLocalVariableSet* dlv = list->at(i);
        list->remove_at(i);
        // individual jvmtiDeferredLocalVariableSet are CHeapObj's
        delete dlv;
      } else {
        i++;
      }
    } while ( i < list->length() );
    if (list->length() == 0) {
      thread->set_deferred_locals(NULL);
      // free the list and elements back to C heap.
      delete list;
    }

  }

  // Compute the caller frame based on the sender sp of stub_frame and stored frame sizes info.
  CodeBlob* cb = stub_frame.cb();
  // Verify we have the right vframeArray
  assert(cb->frame_size() >= 0, "Unexpected frame size");
  intptr_t* unpack_sp = stub_frame.sp() + cb->frame_size();

#ifdef ASSERT
  assert(cb->is_deoptimization_stub() || cb->is_uncommon_trap_stub(), "just checking");
  Events::log("fetch unroll sp " INTPTR_FORMAT, unpack_sp);
#endif
  // This is a guarantee instead of an assert because if vframe doesn't match
  // we will unpack the wrong deoptimized frame and wind up in strange places
  // where it will be very difficult to figure out what went wrong. Better
  // to die an early death here than some very obscure death later when the
  // trail is cold.
  // Note: on ia64 this guarantee can be fooled by frames with no memory stack
  // in that it will fail to detect a problem when there is one. This needs
  // more work in tiger timeframe.
  guarantee(array->unextended_sp() == unpack_sp, "vframe_array_head must contain the vframeArray to unpack");

  int number_of_frames = array->frames();

  // Compute the vframes' sizes.  Note that frame_sizes[] entries are ordered from outermost to innermost
  // virtual activation, which is the reverse of the elements in the vframes array.
  intptr_t* frame_sizes = NEW_C_HEAP_ARRAY(intptr_t, number_of_frames);
  // +1 because we always have an interpreter return address for the final slot.
  address* frame_pcs = NEW_C_HEAP_ARRAY(address, number_of_frames + 1);
  int callee_parameters = 0;
  int callee_locals = 0;
  int popframe_extra_args = 0;
  // Create an interpreter return address for the stub to use as its return
  // address so the skeletal frames are perfectly walkable
  frame_pcs[number_of_frames] = Interpreter::deopt_entry(vtos, 0);

  // PopFrame requires that the preserved incoming arguments from the recently-popped topmost
  // activation be put back on the expression stack of the caller for reexecution
  if (JvmtiExport::can_pop_frame() && thread->popframe_forcing_deopt_reexecution()) {
    popframe_extra_args = in_words(thread->popframe_preserved_args_size_in_words());
  }

  //
  // frame_sizes/frame_pcs[0] oldest frame (int or c2i)
  // frame_sizes/frame_pcs[1] next oldest frame (int)
  // frame_sizes/frame_pcs[n] youngest frame (int)
  //
  // Now a pc in frame_pcs is actually the return address to the frame's caller (a frame
  // owns the space for the return address to it's caller).  Confusing ain't it.
  //
  // The vframe array can address vframes with indices running from
  // 0.._frames-1. Index  0 is the youngest frame and _frame - 1 is the oldest (root) frame.
  // When we create the skeletal frames we need the oldest frame to be in the zero slot
  // in the frame_sizes/frame_pcs so the assembly code can do a trivial walk.
  // so things look a little strange in this loop.
  //
  for (int index = 0; index < array->frames(); index++ ) {
    // frame[number_of_frames - 1 ] = on_stack_size(youngest)
    // frame[number_of_frames - 2 ] = on_stack_size(sender(youngest))
    // frame[number_of_frames - 3 ] = on_stack_size(sender(sender(youngest)))
    frame_sizes[number_of_frames - 1 - index] = BytesPerWord * array->element(index)->on_stack_size(callee_parameters,
                                                                                                    callee_locals,
                                                                                                    index == 0,
                                                                                                    popframe_extra_args);
    // This pc doesn't have to be perfect just good enough to identify the frame
    // as interpreted so the skeleton frame will be walkable
    // The correct pc will be set when the skeleton frame is completely filled out
    // The final pc we store in the loop is wrong and will be overwritten below
    frame_pcs[number_of_frames - 1 - index ] = Interpreter::deopt_entry(vtos, 0) - frame::pc_return_offset;

    callee_parameters = array->element(index)->method()->size_of_parameters();
    callee_locals = array->element(index)->method()->max_locals();
    popframe_extra_args = 0;
  }

  // Compute whether the root vframe returns a float or double value.
  BasicType return_type;
  {
    HandleMark hm;
    methodHandle method(thread, array->element(0)->method());
    Bytecode_invoke* invoke = Bytecode_invoke_at_check(method, array->element(0)->bci());
    return_type = (invoke != NULL) ? invoke->result_type(thread) : T_ILLEGAL;
  }

  // Compute information for handling adapters and adjusting the frame size of the caller.
  int caller_adjustment = 0;

  // Find the current pc for sender of the deoptee. Since the sender may have been deoptimized
  // itself since the deoptee vframeArray was created we must get a fresh value of the pc rather
  // than simply use array->sender.pc(). This requires us to walk the current set of frames
  //
  frame deopt_sender = stub_frame.sender(&dummy_map); // First is the deoptee frame
  deopt_sender = deopt_sender.sender(&dummy_map);     // Now deoptee caller

  // Compute the amount the oldest interpreter frame will have to adjust
  // its caller's stack by. If the caller is a compiled frame then
  // we pretend that the callee has no parameters so that the
  // extension counts for the full amount of locals and not just
  // locals-parms. This is because without a c2i adapter the parm
  // area as created by the compiled frame will not be usable by
  // the interpreter. (Depending on the calling convention there
  // may not even be enough space).

  // QQQ I'd rather see this pushed down into last_frame_adjust
  // and have it take the sender (aka caller).

  if (deopt_sender.is_compiled_frame()) {
    caller_adjustment = last_frame_adjust(0, callee_locals);
  } else if (callee_locals > callee_parameters) {
    // The caller frame may need extending to accommodate
    // non-parameter locals of the first unpacked interpreted frame.
    // Compute that adjustment.
    caller_adjustment = last_frame_adjust(callee_parameters, callee_locals);
  }


  // If the sender is deoptimized the we must retrieve the address of the handler
  // since the frame will "magically" show the original pc before the deopt
  // and we'd undo the deopt.

  frame_pcs[0] = deopt_sender.raw_pc();

  assert(CodeCache::find_blob_unsafe(frame_pcs[0]) != NULL, "bad pc");

  UnrollBlock* info = new UnrollBlock(array->frame_size() * BytesPerWord,
                                      caller_adjustment * BytesPerWord,
                                      number_of_frames,
                                      frame_sizes,
                                      frame_pcs,
                                      return_type);
#if defined(IA32) || defined(AMD64)
  // We need a way to pass fp to the unpacking code so the skeletal frames
  // come out correct. This is only needed for x86 because of c2 using ebp
  // as an allocatable register. So this update is useless (and harmless)
  // on the other platforms. It would be nice to do this in a different
  // way but even the old style deoptimization had a problem with deriving
  // this value. NEEDS_CLEANUP
  // Note: now that c1 is using c2's deopt blob we must do this on all
  // x86 based platforms
  intptr_t** fp_addr = (intptr_t**) (((address)info) + info->initial_fp_offset_in_bytes());
  *fp_addr = array->sender().fp(); // was adapter_caller
#endif /* IA32 || AMD64 */

  if (array->frames() > 1) {
    if (VerifyStack && TraceDeoptimization) {
      tty->print_cr("Deoptimizing method containing inlining");
    }
  }

  array->set_unroll_block(info);
  return info;
}

// Called to cleanup deoptimization data structures in normal case
// after unpacking to stack and when stack overflow error occurs
void Deoptimization::cleanup_deopt_info(JavaThread *thread,
                                        vframeArray *array) {

  // Get array if coming from exception
  if (array == NULL) {
    array = thread->vframe_array_head();
  }
  thread->set_vframe_array_head(NULL);

  // Free the previous UnrollBlock
  vframeArray* old_array = thread->vframe_array_last();
  thread->set_vframe_array_last(array);

  if (old_array != NULL) {
    UnrollBlock* old_info = old_array->unroll_block();
    old_array->set_unroll_block(NULL);
    delete old_info;
    delete old_array;
  }

  // Deallocate any resource creating in this routine and any ResourceObjs allocated
  // inside the vframeArray (StackValueCollections)

  delete thread->deopt_mark();
  thread->set_deopt_mark(NULL);


  if (JvmtiExport::can_pop_frame()) {
#ifndef CC_INTERP
    // Regardless of whether we entered this routine with the pending
    // popframe condition bit set, we should always clear it now
    thread->clear_popframe_condition();
#else
    // C++ interpeter will clear has_pending_popframe when it enters
    // with method_resume. For deopt_resume2 we clear it now.
    if (thread->popframe_forcing_deopt_reexecution())
        thread->clear_popframe_condition();
#endif /* CC_INTERP */
  }

  // unpack_frames() is called at the end of the deoptimization handler
  // and (in C2) at the end of the uncommon trap handler. Note this fact
  // so that an asynchronous stack walker can work again. This counter is
  // incremented at the beginning of fetch_unroll_info() and (in C2) at
  // the beginning of uncommon_trap().
  thread->dec_in_deopt_handler();
}


// Return BasicType of value being returned
JRT_LEAF(BasicType, Deoptimization::unpack_frames(JavaThread* thread, int exec_mode))

  // We are already active int he special DeoptResourceMark any ResourceObj's we
  // allocate will be freed at the end of the routine.

  // It is actually ok to allocate handles in a leaf method. It causes no safepoints,
  // but makes the entry a little slower. There is however a little dance we have to
  // do in debug mode to get around the NoHandleMark code in the JRT_LEAF macro
  ResetNoHandleMark rnhm; // No-op in release/product versions
  HandleMark hm;

  frame stub_frame = thread->last_frame();

  // Since the frame to unpack is the top frame of this thread, the vframe_array_head
  // must point to the vframeArray for the unpack frame.
  vframeArray* array = thread->vframe_array_head();

#ifndef PRODUCT
  if (TraceDeoptimization) {
    tty->print_cr("DEOPT UNPACKING thread " INTPTR_FORMAT " vframeArray " INTPTR_FORMAT " mode %d", thread, array, exec_mode);
  }
#endif

  UnrollBlock* info = array->unroll_block();

  // Unpack the interpreter frames and any adapter frame (c2 only) we might create.
  array->unpack_to_stack(stub_frame, exec_mode);

  BasicType bt = info->return_type();

  // If we have an exception pending, claim that the return type is an oop
  // so the deopt_blob does not overwrite the exception_oop.

  if (exec_mode == Unpack_exception)
    bt = T_OBJECT;

  // Cleanup thread deopt data
  cleanup_deopt_info(thread, array);

#ifndef PRODUCT
  if (VerifyStack) {
    ResourceMark res_mark;

    // Verify that the just-unpacked frames match the interpreter's
    // notions of expression stack and locals
    vframeArray* cur_array = thread->vframe_array_last();
    RegisterMap rm(thread, false);
    rm.set_include_argument_oops(false);
    bool is_top_frame = true;
    int callee_size_of_parameters = 0;
    int callee_max_locals = 0;
    for (int i = 0; i < cur_array->frames(); i++) {
      vframeArrayElement* el = cur_array->element(i);
      frame* iframe = el->iframe();
      guarantee(iframe->is_interpreted_frame(), "Wrong frame type");

      // Get the oop map for this bci
      InterpreterOopMap mask;
      int cur_invoke_parameter_size = 0;
      bool try_next_mask = false;
      int next_mask_expression_stack_size = -1;
      int top_frame_expression_stack_adjustment = 0;
      methodHandle mh(thread, iframe->interpreter_frame_method());
      OopMapCache::compute_one_oop_map(mh, iframe->interpreter_frame_bci(), &mask);
      BytecodeStream str(mh);
      str.set_start(iframe->interpreter_frame_bci());
      int max_bci = mh->code_size();
      // Get to the next bytecode if possible
      assert(str.bci() < max_bci, "bci in interpreter frame out of bounds");
      // Check to see if we can grab the number of outgoing arguments
      // at an uncommon trap for an invoke (where the compiler
      // generates debug info before the invoke has executed)
      Bytecodes::Code cur_code = str.next();
      if (cur_code == Bytecodes::_invokevirtual ||
          cur_code == Bytecodes::_invokespecial ||
          cur_code == Bytecodes::_invokestatic  ||
          cur_code == Bytecodes::_invokeinterface) {
        Bytecode_invoke* invoke = Bytecode_invoke_at(mh, iframe->interpreter_frame_bci());
        symbolHandle signature(thread, invoke->signature());
        ArgumentSizeComputer asc(signature);
        cur_invoke_parameter_size = asc.size();
        if (cur_code != Bytecodes::_invokestatic) {
          // Add in receiver
          ++cur_invoke_parameter_size;
        }
      }
      if (str.bci() < max_bci) {
        Bytecodes::Code bc = str.next();
        if (bc >= 0) {
          // The interpreter oop map generator reports results before
          // the current bytecode has executed except in the case of
          // calls. It seems to be hard to tell whether the compiler
          // has emitted debug information matching the "state before"
          // a given bytecode or the state after, so we try both
          switch (cur_code) {
            case Bytecodes::_invokevirtual:
            case Bytecodes::_invokespecial:
            case Bytecodes::_invokestatic:
            case Bytecodes::_invokeinterface:
            case Bytecodes::_athrow:
              break;
            default: {
              InterpreterOopMap next_mask;
              OopMapCache::compute_one_oop_map(mh, str.bci(), &next_mask);
              next_mask_expression_stack_size = next_mask.expression_stack_size();
              // Need to subtract off the size of the result type of
              // the bytecode because this is not described in the
              // debug info but returned to the interpreter in the TOS
              // caching register
              BasicType bytecode_result_type = Bytecodes::result_type(cur_code);
              if (bytecode_result_type != T_ILLEGAL) {
                top_frame_expression_stack_adjustment = type2size[bytecode_result_type];
              }
              assert(top_frame_expression_stack_adjustment >= 0, "");
              try_next_mask = true;
              break;
            }
          }
        }
      }

      // Verify stack depth and oops in frame
      // This assertion may be dependent on the platform we're running on and may need modification (tested on x86 and sparc)
      if (!(
            /* SPARC */
            (iframe->interpreter_frame_expression_stack_size() == mask.expression_stack_size() + callee_size_of_parameters) ||
            /* x86 */
            (iframe->interpreter_frame_expression_stack_size() == mask.expression_stack_size() + callee_max_locals) ||
            (try_next_mask &&
             (iframe->interpreter_frame_expression_stack_size() == (next_mask_expression_stack_size -
                                                                    top_frame_expression_stack_adjustment))) ||
            (is_top_frame && (exec_mode == Unpack_exception) && iframe->interpreter_frame_expression_stack_size() == 0) ||
            (is_top_frame && (exec_mode == Unpack_uncommon_trap || exec_mode == Unpack_reexecute) &&
             (iframe->interpreter_frame_expression_stack_size() == mask.expression_stack_size() + cur_invoke_parameter_size))
            )) {
        ttyLocker ttyl;

        // Print out some information that will help us debug the problem
        tty->print_cr("Wrong number of expression stack elements during deoptimization");
        tty->print_cr("  Error occurred while verifying frame %d (0..%d, 0 is topmost)", i, cur_array->frames() - 1);
        tty->print_cr("  Fabricated interpreter frame had %d expression stack elements",
                      iframe->interpreter_frame_expression_stack_size());
        tty->print_cr("  Interpreter oop map had %d expression stack elements", mask.expression_stack_size());
        tty->print_cr("  try_next_mask = %d", try_next_mask);
        tty->print_cr("  next_mask_expression_stack_size = %d", next_mask_expression_stack_size);
        tty->print_cr("  callee_size_of_parameters = %d", callee_size_of_parameters);
        tty->print_cr("  callee_max_locals = %d", callee_max_locals);
        tty->print_cr("  top_frame_expression_stack_adjustment = %d", top_frame_expression_stack_adjustment);
        tty->print_cr("  exec_mode = %d", exec_mode);
        tty->print_cr("  cur_invoke_parameter_size = %d", cur_invoke_parameter_size);
        tty->print_cr("  Thread = " INTPTR_FORMAT ", thread ID = " UINTX_FORMAT, thread, thread->osthread()->thread_id());
        tty->print_cr("  Interpreted frames:");
        for (int k = 0; k < cur_array->frames(); k++) {
          vframeArrayElement* el = cur_array->element(k);
          tty->print_cr("    %s (bci %d)", el->method()->name_and_sig_as_C_string(), el->bci());
        }
        cur_array->print_on_2(tty);
        guarantee(false, "wrong number of expression stack elements during deopt");
      }
      VerifyOopClosure verify;
      iframe->oops_interpreted_do(&verify, &rm, false);
      callee_size_of_parameters = mh->size_of_parameters();
      callee_max_locals = mh->max_locals();
      is_top_frame = false;
    }
  }
#endif /* !PRODUCT */


  return bt;
JRT_END


int Deoptimization::deoptimize_dependents() {
  Threads::deoptimized_wrt_marked_nmethods();
  return 0;
}


#ifdef COMPILER2
bool Deoptimization::realloc_objects(JavaThread* thread, frame* fr, GrowableArray<ScopeValue*>* objects, TRAPS) {
  Handle pending_exception(thread->pending_exception());
  const char* exception_file = thread->exception_file();
  int exception_line = thread->exception_line();
  thread->clear_pending_exception();

  for (int i = 0; i < objects->length(); i++) {
    assert(objects->at(i)->is_object(), "invalid debug information");
    ObjectValue* sv = (ObjectValue*) objects->at(i);

    KlassHandle k(((ConstantOopReadValue*) sv->klass())->value()());
    oop obj = NULL;

    if (k->oop_is_instance()) {
      instanceKlass* ik = instanceKlass::cast(k());
      obj = ik->allocate_instance(CHECK_(false));
    } else if (k->oop_is_typeArray()) {
      typeArrayKlass* ak = typeArrayKlass::cast(k());
      assert(sv->field_size() % type2size[ak->element_type()] == 0, "non-integral array length");
      int len = sv->field_size() / type2size[ak->element_type()];
      obj = ak->allocate(len, CHECK_(false));
    } else if (k->oop_is_objArray()) {
      objArrayKlass* ak = objArrayKlass::cast(k());
      obj = ak->allocate(sv->field_size(), CHECK_(false));
    }

    assert(obj != NULL, "allocation failed");
    assert(sv->value().is_null(), "redundant reallocation");
    sv->set_value(obj);
  }

  if (pending_exception.not_null()) {
    thread->set_pending_exception(pending_exception(), exception_file, exception_line);
  }

  return true;
}

// This assumes that the fields are stored in ObjectValue in the same order
// they are yielded by do_nonstatic_fields.
class FieldReassigner: public FieldClosure {
  frame* _fr;
  RegisterMap* _reg_map;
  ObjectValue* _sv;
  instanceKlass* _ik;
  oop _obj;

  int _i;
public:
  FieldReassigner(frame* fr, RegisterMap* reg_map, ObjectValue* sv, oop obj) :
    _fr(fr), _reg_map(reg_map), _sv(sv), _obj(obj), _i(0) {}

  int i() const { return _i; }


  void do_field(fieldDescriptor* fd) {
    StackValue* value =
      StackValue::create_stack_value(_fr, _reg_map, _sv->field_at(i()));
    int offset = fd->offset();
    switch (fd->field_type()) {
    case T_OBJECT: case T_ARRAY:
      assert(value->type() == T_OBJECT, "Agreement.");
      _obj->obj_field_put(offset, value->get_obj()());
      break;

    case T_LONG: case T_DOUBLE: {
      assert(value->type() == T_INT, "Agreement.");
      StackValue* low =
        StackValue::create_stack_value(_fr, _reg_map, _sv->field_at(++_i));
      jlong res = jlong_from((jint)value->get_int(), (jint)low->get_int());
      _obj->long_field_put(offset, res);
      break;
    }

    case T_INT: case T_FLOAT: // 4 bytes.
      assert(value->type() == T_INT, "Agreement.");
      _obj->int_field_put(offset, (jint)value->get_int());
      break;

    case T_SHORT: case T_CHAR: // 2 bytes
      assert(value->type() == T_INT, "Agreement.");
      _obj->short_field_put(offset, (jshort)value->get_int());
      break;

    case T_BOOLEAN: // 1 byte
      assert(value->type() == T_INT, "Agreement.");
      _obj->bool_field_put(offset, (jboolean)value->get_int());
      break;

    default:
      ShouldNotReachHere();
    }
    _i++;
  }
};

// restore elements of an eliminated type array
void Deoptimization::reassign_type_array_elements(frame* fr, RegisterMap* reg_map, ObjectValue* sv, typeArrayOop obj, BasicType type) {
  StackValue* low;
  jlong lval;
  int index = 0;

  for (int i = 0; i < sv->field_size(); i++) {
    StackValue* value = StackValue::create_stack_value(fr, reg_map, sv->field_at(i));
    switch(type) {
      case T_BOOLEAN: obj->bool_at_put (index, (jboolean) value->get_int()); break;
      case T_BYTE:    obj->byte_at_put (index, (jbyte)    value->get_int()); break;
      case T_CHAR:    obj->char_at_put (index, (jchar)    value->get_int()); break;
      case T_SHORT:   obj->short_at_put(index, (jshort)   value->get_int()); break;
      case T_INT:     obj->int_at_put  (index, (jint)     value->get_int()); break;
      case T_FLOAT:   obj->float_at_put(index, (jfloat)   value->get_int()); break;
      case T_LONG:
      case T_DOUBLE:
        low = StackValue::create_stack_value(fr, reg_map, sv->field_at(++i));
        lval = jlong_from((jint)value->get_int(), (jint)low->get_int());
        sv->value()->long_field_put(index, lval);
        break;
      default:
        ShouldNotReachHere();
    }
    index++;
  }
}


// restore fields of an eliminated object array
void Deoptimization::reassign_object_array_elements(frame* fr, RegisterMap* reg_map, ObjectValue* sv, objArrayOop obj) {
  for (int i = 0; i < sv->field_size(); i++) {
    StackValue* value = StackValue::create_stack_value(fr, reg_map, sv->field_at(i));
    assert(value->type() == T_OBJECT, "object element expected");
    obj->obj_at_put(i, value->get_obj()());
  }
}


// restore fields of all eliminated objects and arrays
void Deoptimization::reassign_fields(frame* fr, RegisterMap* reg_map, GrowableArray<ScopeValue*>* objects) {
  for (int i = 0; i < objects->length(); i++) {
    ObjectValue* sv = (ObjectValue*) objects->at(i);
    KlassHandle k(((ConstantOopReadValue*) sv->klass())->value()());
    Handle obj = sv->value();
    assert(obj.not_null(), "reallocation was missed");

    if (k->oop_is_instance()) {
      instanceKlass* ik = instanceKlass::cast(k());
      FieldReassigner reassign(fr, reg_map, sv, obj());
      ik->do_nonstatic_fields(&reassign);
    } else if (k->oop_is_typeArray()) {
      typeArrayKlass* ak = typeArrayKlass::cast(k());
      reassign_type_array_elements(fr, reg_map, sv, (typeArrayOop) obj(), ak->element_type());
    } else if (k->oop_is_objArray()) {
      reassign_object_array_elements(fr, reg_map, sv, (objArrayOop) obj());
    }
  }
}


// relock objects for which synchronization was eliminated
void Deoptimization::relock_objects(frame* fr, RegisterMap* reg_map, GrowableArray<MonitorValue*>* monitors) {
  for (int i = 0; i < monitors->length(); i++) {
    MonitorValue* mv = monitors->at(i);
    StackValue* owner = StackValue::create_stack_value(fr, reg_map, mv->owner());
    if (mv->eliminated()) {
      Handle obj = owner->get_obj();
      assert(obj.not_null(), "reallocation was missed");
      BasicLock* lock = StackValue::resolve_monitor_lock(fr, mv->basic_lock());
      lock->set_displaced_header(obj->mark());
      obj->set_mark((markOop) lock);
    }
    assert(owner->get_obj()->is_locked(), "object must be locked now");
  }
}


#ifndef PRODUCT
// print information about reallocated objects
void Deoptimization::print_objects(GrowableArray<ScopeValue*>* objects) {
  fieldDescriptor fd;

  for (int i = 0; i < objects->length(); i++) {
    ObjectValue* sv = (ObjectValue*) objects->at(i);
    KlassHandle k(((ConstantOopReadValue*) sv->klass())->value()());
    Handle obj = sv->value();

    tty->print("     object <" INTPTR_FORMAT "> of type ", sv->value()());
    k->as_klassOop()->print_value();
    tty->print(" allocated (%d bytes)", obj->size() * HeapWordSize);
    tty->cr();

    if (Verbose) {
      k->oop_print_on(obj(), tty);
    }
  }
}
#endif
#endif // COMPILER2

vframeArray* Deoptimization::create_vframeArray(JavaThread* thread, frame fr, RegisterMap *reg_map, GrowableArray<compiledVFrame*>* chunk) {

#ifndef PRODUCT
  if (TraceDeoptimization) {
    ttyLocker ttyl;
    tty->print("DEOPT PACKING thread " INTPTR_FORMAT " ", thread);
    fr.print_on(tty);
    tty->print_cr("     Virtual frames (innermost first):");
    for (int index = 0; index < chunk->length(); index++) {
      compiledVFrame* vf = chunk->at(index);
      tty->print("       %2d - ", index);
      vf->print_value();
      int bci = chunk->at(index)->raw_bci();
      const char* code_name;
      if (bci == SynchronizationEntryBCI) {
        code_name = "sync entry";
      } else {
        Bytecodes::Code code = Bytecodes::code_at(vf->method(), bci);
        code_name = Bytecodes::name(code);
      }
      tty->print(" - %s", code_name);
      tty->print_cr(" @ bci %d ", bci);
      if (Verbose) {
        vf->print();
        tty->cr();
      }
    }
  }
#endif

  // Register map for next frame (used for stack crawl).  We capture
  // the state of the deopt'ing frame's caller.  Thus if we need to
  // stuff a C2I adapter we can properly fill in the callee-save
  // register locations.
  frame caller = fr.sender(reg_map);
  int frame_size = caller.sp() - fr.sp();

  frame sender = caller;

  // Since the Java thread being deoptimized will eventually adjust it's own stack,
  // the vframeArray containing the unpacking information is allocated in the C heap.
  // For Compiler1, the caller of the deoptimized frame is saved for use by unpack_frames().
  vframeArray* array = vframeArray::allocate(thread, frame_size, chunk, reg_map, sender, caller, fr);

  // Compare the vframeArray to the collected vframes
  assert(array->structural_compare(thread, chunk), "just checking");
  Events::log("# vframes = %d", (intptr_t)chunk->length());

#ifndef PRODUCT
  if (TraceDeoptimization) {
    ttyLocker ttyl;
    tty->print_cr("     Created vframeArray " INTPTR_FORMAT, array);
    if (Verbose) {
      int count = 0;
      // this used to leak deoptimizedVFrame like it was going out of style!!!
      for (int index = 0; index < array->frames(); index++ ) {
        vframeArrayElement* e = array->element(index);
        e->print(tty);

        /*
          No printing yet.
        array->vframe_at(index)->print_activation(count++);
        // better as...
        array->print_activation_for(index, count++);
        */
      }
    }
  }
#endif // PRODUCT

  return array;
}


static void collect_monitors(compiledVFrame* cvf, GrowableArray<Handle>* objects_to_revoke) {
  GrowableArray<MonitorInfo*>* monitors = cvf->monitors();
  for (int i = 0; i < monitors->length(); i++) {
    MonitorInfo* mon_info = monitors->at(i);
    if (mon_info->owner() != NULL) {
      objects_to_revoke->append(Handle(mon_info->owner()));
    }
  }
}


void Deoptimization::revoke_biases_of_monitors(JavaThread* thread, frame fr, RegisterMap* map) {
  if (!UseBiasedLocking) {
    return;
  }

  GrowableArray<Handle>* objects_to_revoke = new GrowableArray<Handle>();

  // Unfortunately we don't have a RegisterMap available in most of
  // the places we want to call this routine so we need to walk the
  // stack again to update the register map.
  if (map == NULL || !map->update_map()) {
    StackFrameStream sfs(thread, true);
    bool found = false;
    while (!found && !sfs.is_done()) {
      frame* cur = sfs.current();
      sfs.next();
      found = cur->id() == fr.id();
    }
    assert(found, "frame to be deoptimized not found on target thread's stack");
    map = sfs.register_map();
  }

  vframe* vf = vframe::new_vframe(&fr, map, thread);
  compiledVFrame* cvf = compiledVFrame::cast(vf);
  // Revoke monitors' biases in all scopes
  while (!cvf->is_top()) {
    collect_monitors(cvf, objects_to_revoke);
    cvf = compiledVFrame::cast(cvf->sender());
  }
  collect_monitors(cvf, objects_to_revoke);

  if (SafepointSynchronize::is_at_safepoint()) {
    BiasedLocking::revoke_at_safepoint(objects_to_revoke);
  } else {
    BiasedLocking::revoke(objects_to_revoke);
  }
}


void Deoptimization::revoke_biases_of_monitors(CodeBlob* cb) {
  if (!UseBiasedLocking) {
    return;
  }

  assert(SafepointSynchronize::is_at_safepoint(), "must only be called from safepoint");
  GrowableArray<Handle>* objects_to_revoke = new GrowableArray<Handle>();
  for (JavaThread* jt = Threads::first(); jt != NULL ; jt = jt->next()) {
    if (jt->has_last_Java_frame()) {
      StackFrameStream sfs(jt, true);
      while (!sfs.is_done()) {
        frame* cur = sfs.current();
        if (cb->contains(cur->pc())) {
          vframe* vf = vframe::new_vframe(cur, sfs.register_map(), jt);
          compiledVFrame* cvf = compiledVFrame::cast(vf);
          // Revoke monitors' biases in all scopes
          while (!cvf->is_top()) {
            collect_monitors(cvf, objects_to_revoke);
            cvf = compiledVFrame::cast(cvf->sender());
          }
          collect_monitors(cvf, objects_to_revoke);
        }
        sfs.next();
      }
    }
  }
  BiasedLocking::revoke_at_safepoint(objects_to_revoke);
}


void Deoptimization::deoptimize_single_frame(JavaThread* thread, frame fr) {
  assert(fr.can_be_deoptimized(), "checking frame type");

  gather_statistics(Reason_constraint, Action_none, Bytecodes::_illegal);

  EventMark m("Deoptimization (pc=" INTPTR_FORMAT ", sp=" INTPTR_FORMAT ")", fr.pc(), fr.id());

  // Patch the nmethod so that when execution returns to it we will
  // deopt the execution state and return to the interpreter.
  fr.deoptimize(thread);
}

void Deoptimization::deoptimize(JavaThread* thread, frame fr, RegisterMap *map) {
  // Deoptimize only if the frame comes from compile code.
  // Do not deoptimize the frame which is already patched
  // during the execution of the loops below.
  if (!fr.is_compiled_frame() || fr.is_deoptimized_frame()) {
    return;
  }
  ResourceMark rm;
  DeoptimizationMarker dm;
  if (UseBiasedLocking) {
    revoke_biases_of_monitors(thread, fr, map);
  }
  deoptimize_single_frame(thread, fr);

}


void Deoptimization::deoptimize_frame(JavaThread* thread, intptr_t* id) {
  // Compute frame and register map based on thread and sp.
  RegisterMap reg_map(thread, UseBiasedLocking);
  frame fr = thread->last_frame();
  while (fr.id() != id) {
    fr = fr.sender(&reg_map);
  }
  deoptimize(thread, fr, &reg_map);
}


// JVMTI PopFrame support
JRT_LEAF(void, Deoptimization::popframe_preserve_args(JavaThread* thread, int bytes_to_save, void* start_address))
{
  thread->popframe_preserve_args(in_ByteSize(bytes_to_save), start_address);
}
JRT_END


#ifdef COMPILER2
void Deoptimization::load_class_by_index(constantPoolHandle constant_pool, int index, TRAPS) {
  // in case of an unresolved klass entry, load the class.
  if (constant_pool->tag_at(index).is_unresolved_klass()) {
    klassOop tk = constant_pool->klass_at(index, CHECK);
    return;
  }

  if (!constant_pool->tag_at(index).is_symbol()) return;

  Handle class_loader (THREAD, instanceKlass::cast(constant_pool->pool_holder())->class_loader());
  symbolHandle symbol (THREAD, constant_pool->symbol_at(index));

  // class name?
  if (symbol->byte_at(0) != '(') {
    Handle protection_domain (THREAD, Klass::cast(constant_pool->pool_holder())->protection_domain());
    SystemDictionary::resolve_or_null(symbol, class_loader, protection_domain, CHECK);
    return;
  }

  // then it must be a signature!
  for (SignatureStream ss(symbol); !ss.is_done(); ss.next()) {
    if (ss.is_object()) {
      symbolOop s = ss.as_symbol(CHECK);
      symbolHandle class_name (THREAD, s);
      Handle protection_domain (THREAD, Klass::cast(constant_pool->pool_holder())->protection_domain());
      SystemDictionary::resolve_or_null(class_name, class_loader, protection_domain, CHECK);
    }
  }
}


void Deoptimization::load_class_by_index(constantPoolHandle constant_pool, int index) {
  EXCEPTION_MARK;
  load_class_by_index(constant_pool, index, THREAD);
  if (HAS_PENDING_EXCEPTION) {
    // Exception happened during classloading. We ignore the exception here, since it
    // is going to be rethrown since the current activation is going to be deoptimzied and
    // the interpreter will re-execute the bytecode.
    CLEAR_PENDING_EXCEPTION;
  }
}

JRT_ENTRY(void, Deoptimization::uncommon_trap_inner(JavaThread* thread, jint trap_request)) {
  HandleMark hm;

  // uncommon_trap() is called at the beginning of the uncommon trap
  // handler. Note this fact before we start generating temporary frames
  // that can confuse an asynchronous stack walker. This counter is
  // decremented at the end of unpack_frames().
  thread->inc_in_deopt_handler();

  // We need to update the map if we have biased locking.
  RegisterMap reg_map(thread, UseBiasedLocking);
  frame stub_frame = thread->last_frame();
  frame fr = stub_frame.sender(&reg_map);
  // Make sure the calling nmethod is not getting deoptimized and removed
  // before we are done with it.
  nmethodLocker nl(fr.pc());

  {
    ResourceMark rm;

    // Revoke biases of any monitors in the frame to ensure we can migrate them
    revoke_biases_of_monitors(thread, fr, &reg_map);

    DeoptReason reason = trap_request_reason(trap_request);
    DeoptAction action = trap_request_action(trap_request);
    jint unloaded_class_index = trap_request_index(trap_request); // CP idx or -1

    Events::log("Uncommon trap occurred @" INTPTR_FORMAT " unloaded_class_index = %d", fr.pc(), (int) trap_request);
    vframe*  vf  = vframe::new_vframe(&fr, &reg_map, thread);
    compiledVFrame* cvf = compiledVFrame::cast(vf);

    nmethod* nm = cvf->code();

    ScopeDesc*      trap_scope  = cvf->scope();
    methodHandle    trap_method = trap_scope->method();
    int             trap_bci    = trap_scope->bci();
    Bytecodes::Code trap_bc     = Bytecode_at(trap_method->bcp_from(trap_bci))->java_code();

    // Record this event in the histogram.
    gather_statistics(reason, action, trap_bc);

    // Ensure that we can record deopt. history:
    bool create_if_missing = ProfileTraps;

    methodDataHandle trap_mdo
      (THREAD, get_method_data(thread, trap_method, create_if_missing));

    // Print a bunch of diagnostics, if requested.
    if (TraceDeoptimization || LogCompilation) {
      ResourceMark rm;
      ttyLocker ttyl;
      char buf[100];
      if (xtty != NULL) {
        xtty->begin_head("uncommon_trap thread='" UINTX_FORMAT"' %s",
                         os::current_thread_id(),
                         format_trap_request(buf, sizeof(buf), trap_request));
        nm->log_identity(xtty);
      }
      symbolHandle class_name;
      bool unresolved = false;
      if (unloaded_class_index >= 0) {
        constantPoolHandle constants (THREAD, trap_method->constants());
        if (constants->tag_at(unloaded_class_index).is_unresolved_klass()) {
          class_name = symbolHandle(THREAD,
            constants->klass_name_at(unloaded_class_index));
          unresolved = true;
          if (xtty != NULL)
            xtty->print(" unresolved='1'");
        } else if (constants->tag_at(unloaded_class_index).is_symbol()) {
          class_name = symbolHandle(THREAD,
            constants->symbol_at(unloaded_class_index));
        }
        if (xtty != NULL)
          xtty->name(class_name);
      }
      if (xtty != NULL && trap_mdo.not_null()) {
        // Dump the relevant MDO state.
        // This is the deopt count for the current reason, any previous
        // reasons or recompiles seen at this point.
        int dcnt = trap_mdo->trap_count(reason);
        if (dcnt != 0)
          xtty->print(" count='%d'", dcnt);
        ProfileData* pdata = trap_mdo->bci_to_data(trap_bci);
        int dos = (pdata == NULL)? 0: pdata->trap_state();
        if (dos != 0) {
          xtty->print(" state='%s'", format_trap_state(buf, sizeof(buf), dos));
          if (trap_state_is_recompiled(dos)) {
            int recnt2 = trap_mdo->overflow_recompile_count();
            if (recnt2 != 0)
              xtty->print(" recompiles2='%d'", recnt2);
          }
        }
      }
      if (xtty != NULL) {
        xtty->stamp();
        xtty->end_head();
      }
      if (TraceDeoptimization) {  // make noise on the tty
        tty->print("Uncommon trap occurred in");
        nm->method()->print_short_name(tty);
        tty->print(" (@" INTPTR_FORMAT ") thread=%d reason=%s action=%s unloaded_class_index=%d",
                   fr.pc(),
                   (int) os::current_thread_id(),
                   trap_reason_name(reason),
                   trap_action_name(action),
                   unloaded_class_index);
        if (class_name.not_null()) {
          tty->print(unresolved ? " unresolved class: " : " symbol: ");
          class_name->print_symbol_on(tty);
        }
        tty->cr();
      }
      if (xtty != NULL) {
        // Log the precise location of the trap.
        for (ScopeDesc* sd = trap_scope; ; sd = sd->sender()) {
          xtty->begin_elem("jvms bci='%d'", sd->bci());
          xtty->method(sd->method());
          xtty->end_elem();
          if (sd->is_top())  break;
        }
        xtty->tail("uncommon_trap");
      }
    }
    // (End diagnostic printout.)

    // Load class if necessary
    if (unloaded_class_index >= 0) {
      constantPoolHandle constants(THREAD, trap_method->constants());
      load_class_by_index(constants, unloaded_class_index);
    }

    // Flush the nmethod if necessary and desirable.
    //
    // We need to avoid situations where we are re-flushing the nmethod
    // because of a hot deoptimization site.  Repeated flushes at the same
    // point need to be detected by the compiler and avoided.  If the compiler
    // cannot avoid them (or has a bug and "refuses" to avoid them), this
    // module must take measures to avoid an infinite cycle of recompilation
    // and deoptimization.  There are several such measures:
    //
    //   1. If a recompilation is ordered a second time at some site X
    //   and for the same reason R, the action is adjusted to 'reinterpret',
    //   to give the interpreter time to exercise the method more thoroughly.
    //   If this happens, the method's overflow_recompile_count is incremented.
    //
    //   2. If the compiler fails to reduce the deoptimization rate, then
    //   the method's overflow_recompile_count will begin to exceed the set
    //   limit PerBytecodeRecompilationCutoff.  If this happens, the action
    //   is adjusted to 'make_not_compilable', and the method is abandoned
    //   to the interpreter.  This is a performance hit for hot methods,
    //   but is better than a disastrous infinite cycle of recompilations.
    //   (Actually, only the method containing the site X is abandoned.)
    //
    //   3. In parallel with the previous measures, if the total number of
    //   recompilations of a method exceeds the much larger set limit
    //   PerMethodRecompilationCutoff, the method is abandoned.
    //   This should only happen if the method is very large and has
    //   many "lukewarm" deoptimizations.  The code which enforces this
    //   limit is elsewhere (class nmethod, class methodOopDesc).
    //
    // Note that the per-BCI 'is_recompiled' bit gives the compiler one chance
    // to recompile at each bytecode independently of the per-BCI cutoff.
    //
    // The decision to update code is up to the compiler, and is encoded
    // in the Action_xxx code.  If the compiler requests Action_none
    // no trap state is changed, no compiled code is changed, and the
    // computation suffers along in the interpreter.
    //
    // The other action codes specify various tactics for decompilation
    // and recompilation.  Action_maybe_recompile is the loosest, and
    // allows the compiled code to stay around until enough traps are seen,
    // and until the compiler gets around to recompiling the trapping method.
    //
    // The other actions cause immediate removal of the present code.

    bool update_trap_state = true;
    bool make_not_entrant = false;
    bool make_not_compilable = false;
    bool reset_counters = false;
    switch (action) {
    case Action_none:
      // Keep the old code.
      update_trap_state = false;
      break;
    case Action_maybe_recompile:
      // Do not need to invalidate the present code, but we can
      // initiate another
      // Start compiler without (necessarily) invalidating the nmethod.
      // The system will tolerate the old code, but new code should be
      // generated when possible.
      break;
    case Action_reinterpret:
      // Go back into the interpreter for a while, and then consider
      // recompiling form scratch.
      make_not_entrant = true;
      // Reset invocation counter for outer most method.
      // This will allow the interpreter to exercise the bytecodes
      // for a while before recompiling.
      // By contrast, Action_make_not_entrant is immediate.
      //
      // Note that the compiler will track null_check, null_assert,
      // range_check, and class_check events and log them as if they
      // had been traps taken from compiled code.  This will update
      // the MDO trap history so that the next compilation will
      // properly detect hot trap sites.
      reset_counters = true;
      break;
    case Action_make_not_entrant:
      // Request immediate recompilation, and get rid of the old code.
      // Make them not entrant, so next time they are called they get
      // recompiled.  Unloaded classes are loaded now so recompile before next
      // time they are called.  Same for uninitialized.  The interpreter will
      // link the missing class, if any.
      make_not_entrant = true;
      break;
    case Action_make_not_compilable:
      // Give up on compiling this method at all.
      make_not_entrant = true;
      make_not_compilable = true;
      break;
    default:
      ShouldNotReachHere();
    }

    // Setting +ProfileTraps fixes the following, on all platforms:
    // 4852688: ProfileInterpreter is off by default for ia64.  The result is
    // infinite heroic-opt-uncommon-trap/deopt/recompile cycles, since the
    // recompile relies on a methodDataOop to record heroic opt failures.

    // Whether the interpreter is producing MDO data or not, we also need
    // to use the MDO to detect hot deoptimization points and control
    // aggressive optimization.
    if (ProfileTraps && update_trap_state && trap_mdo.not_null()) {
      assert(trap_mdo() == get_method_data(thread, trap_method, false), "sanity");
      uint this_trap_count = 0;
      bool maybe_prior_trap = false;
      bool maybe_prior_recompile = false;
      ProfileData* pdata
        = query_update_method_data(trap_mdo, trap_bci, reason,
                                   //outputs:
                                   this_trap_count,
                                   maybe_prior_trap,
                                   maybe_prior_recompile);
      // Because the interpreter also counts null, div0, range, and class
      // checks, these traps from compiled code are double-counted.
      // This is harmless; it just means that the PerXTrapLimit values
      // are in effect a little smaller than they look.

      DeoptReason per_bc_reason = reason_recorded_per_bytecode_if_any(reason);
      if (per_bc_reason != Reason_none) {
        // Now take action based on the partially known per-BCI history.
        if (maybe_prior_trap
            && this_trap_count >= (uint)PerBytecodeTrapLimit) {
          // If there are too many traps at this BCI, force a recompile.
          // This will allow the compiler to see the limit overflow, and
          // take corrective action, if possible.  The compiler generally
          // does not use the exact PerBytecodeTrapLimit value, but instead
          // changes its tactics if it sees any traps at all.  This provides
          // a little hysteresis, delaying a recompile until a trap happens
          // several times.
          //
          // Actually, since there is only one bit of counter per BCI,
          // the possible per-BCI counts are {0,1,(per-method count)}.
          // This produces accurate results if in fact there is only
          // one hot trap site, but begins to get fuzzy if there are
          // many sites.  For example, if there are ten sites each
          // trapping two or more times, they each get the blame for
          // all of their traps.
          make_not_entrant = true;
        }

        // Detect repeated recompilation at the same BCI, and enforce a limit.
        if (make_not_entrant && maybe_prior_recompile) {
          // More than one recompile at this point.
          trap_mdo->inc_overflow_recompile_count();
          if (maybe_prior_trap
              && ((uint)trap_mdo->overflow_recompile_count()
                  > (uint)PerBytecodeRecompilationCutoff)) {
            // Give up on the method containing the bad BCI.
            if (trap_method() == nm->method()) {
              make_not_compilable = true;
            } else {
              trap_method->set_not_compilable();
              // But give grace to the enclosing nm->method().
            }
          }
        }
      } else {
        // For reasons which are not recorded per-bytecode, we simply
        // force recompiles unconditionally.
        // (Note that PerMethodRecompilationCutoff is enforced elsewhere.)
        make_not_entrant = true;
      }

      // Go back to the compiler if there are too many traps in this method.
      if (this_trap_count >= (uint)PerMethodTrapLimit) {
        // If there are too many traps in this method, force a recompile.
        // This will allow the compiler to see the limit overflow, and
        // take corrective action, if possible.
        // (This condition is an unlikely backstop only, because the
        // PerBytecodeTrapLimit is more likely to take effect first,
        // if it is applicable.)
        make_not_entrant = true;
      }

      // Here's more hysteresis:  If there has been a recompile at
      // this trap point already, run the method in the interpreter
      // for a while to exercise it more thoroughly.
      if (make_not_entrant && maybe_prior_recompile && maybe_prior_trap) {
        reset_counters = true;
      }

      if (make_not_entrant && pdata != NULL) {
        // Record the recompilation event, if any.
        int tstate0 = pdata->trap_state();
        int tstate1 = trap_state_set_recompiled(tstate0, true);
        if (tstate1 != tstate0)
          pdata->set_trap_state(tstate1);
      }
    }

    // Take requested actions on the method:

    // Reset invocation counters
    if (reset_counters) {
      if (nm->is_osr_method())
        reset_invocation_counter(trap_scope, CompileThreshold);
      else
        reset_invocation_counter(trap_scope);
    }

    // Recompile
    if (make_not_entrant) {
      nm->make_not_entrant();
    }

    // Give up compiling
    if (make_not_compilable) {
      assert(make_not_entrant, "consistent");
      nm->method()->set_not_compilable();
    }

  } // Free marked resources

}
JRT_END

methodDataOop
Deoptimization::get_method_data(JavaThread* thread, methodHandle m,
                                bool create_if_missing) {
  Thread* THREAD = thread;
  methodDataOop mdo = m()->method_data();
  if (mdo == NULL && create_if_missing && !HAS_PENDING_EXCEPTION) {
    // Build an MDO.  Ignore errors like OutOfMemory;
    // that simply means we won't have an MDO to update.
    methodOopDesc::build_interpreter_method_data(m, THREAD);
    if (HAS_PENDING_EXCEPTION) {
      assert((PENDING_EXCEPTION->is_a(SystemDictionary::OutOfMemoryError_klass())), "we expect only an OOM error here");
      CLEAR_PENDING_EXCEPTION;
    }
    mdo = m()->method_data();
  }
  return mdo;
}

ProfileData*
Deoptimization::query_update_method_data(methodDataHandle trap_mdo,
                                         int trap_bci,
                                         Deoptimization::DeoptReason reason,
                                         //outputs:
                                         uint& ret_this_trap_count,
                                         bool& ret_maybe_prior_trap,
                                         bool& ret_maybe_prior_recompile) {
  uint prior_trap_count = trap_mdo->trap_count(reason);
  uint this_trap_count  = trap_mdo->inc_trap_count(reason);

  // If the runtime cannot find a place to store trap history,
  // it is estimated based on the general condition of the method.
  // If the method has ever been recompiled, or has ever incurred
  // a trap with the present reason , then this BCI is assumed
  // (pessimistically) to be the culprit.
  bool maybe_prior_trap      = (prior_trap_count != 0);
  bool maybe_prior_recompile = (trap_mdo->decompile_count() != 0);
  ProfileData* pdata = NULL;


  // For reasons which are recorded per bytecode, we check per-BCI data.
  DeoptReason per_bc_reason = reason_recorded_per_bytecode_if_any(reason);
  if (per_bc_reason != Reason_none) {
    // Find the profile data for this BCI.  If there isn't one,
    // try to allocate one from the MDO's set of spares.
    // This will let us detect a repeated trap at this point.
    pdata = trap_mdo->allocate_bci_to_data(trap_bci);

    if (pdata != NULL) {
      // Query the trap state of this profile datum.
      int tstate0 = pdata->trap_state();
      if (!trap_state_has_reason(tstate0, per_bc_reason))
        maybe_prior_trap = false;
      if (!trap_state_is_recompiled(tstate0))
        maybe_prior_recompile = false;

      // Update the trap state of this profile datum.
      int tstate1 = tstate0;
      // Record the reason.
      tstate1 = trap_state_add_reason(tstate1, per_bc_reason);
      // Store the updated state on the MDO, for next time.
      if (tstate1 != tstate0)
        pdata->set_trap_state(tstate1);
    } else {
      if (LogCompilation && xtty != NULL)
        // Missing MDP?  Leave a small complaint in the log.
        xtty->elem("missing_mdp bci='%d'", trap_bci);
    }
  }

  // Return results:
  ret_this_trap_count = this_trap_count;
  ret_maybe_prior_trap = maybe_prior_trap;
  ret_maybe_prior_recompile = maybe_prior_recompile;
  return pdata;
}

void
Deoptimization::update_method_data_from_interpreter(methodDataHandle trap_mdo, int trap_bci, int reason) {
  ResourceMark rm;
  // Ignored outputs:
  uint ignore_this_trap_count;
  bool ignore_maybe_prior_trap;
  bool ignore_maybe_prior_recompile;
  query_update_method_data(trap_mdo, trap_bci,
                           (DeoptReason)reason,
                           ignore_this_trap_count,
                           ignore_maybe_prior_trap,
                           ignore_maybe_prior_recompile);
}

void Deoptimization::reset_invocation_counter(ScopeDesc* trap_scope, jint top_count) {
  ScopeDesc* sd = trap_scope;
  for (; !sd->is_top(); sd = sd->sender()) {
    // Reset ICs of inlined methods, since they can trigger compilations also.
    sd->method()->invocation_counter()->reset();
  }
  InvocationCounter* c = sd->method()->invocation_counter();
  if (top_count != _no_count) {
    // It was an OSR method, so bump the count higher.
    c->set(c->state(), top_count);
  } else {
    c->reset();
  }
  sd->method()->backedge_counter()->reset();
}

Deoptimization::UnrollBlock* Deoptimization::uncommon_trap(JavaThread* thread, jint trap_request) {

  // Still in Java no safepoints
  {
    // This enters VM and may safepoint
    uncommon_trap_inner(thread, trap_request);
  }
  return fetch_unroll_info_helper(thread);
}

// Local derived constants.
// Further breakdown of DataLayout::trap_state, as promised by DataLayout.
const int DS_REASON_MASK   = DataLayout::trap_mask >> 1;
const int DS_RECOMPILE_BIT = DataLayout::trap_mask - DS_REASON_MASK;

//---------------------------trap_state_reason---------------------------------
Deoptimization::DeoptReason
Deoptimization::trap_state_reason(int trap_state) {
  // This assert provides the link between the width of DataLayout::trap_bits
  // and the encoding of "recorded" reasons.  It ensures there are enough
  // bits to store all needed reasons in the per-BCI MDO profile.
  assert(DS_REASON_MASK >= Reason_RECORDED_LIMIT, "enough bits");
  int recompile_bit = (trap_state & DS_RECOMPILE_BIT);
  trap_state -= recompile_bit;
  if (trap_state == DS_REASON_MASK) {
    return Reason_many;
  } else {
    assert((int)Reason_none == 0, "state=0 => Reason_none");
    return (DeoptReason)trap_state;
  }
}
//-------------------------trap_state_has_reason-------------------------------
int Deoptimization::trap_state_has_reason(int trap_state, int reason) {
  assert(reason_is_recorded_per_bytecode((DeoptReason)reason), "valid reason");
  assert(DS_REASON_MASK >= Reason_RECORDED_LIMIT, "enough bits");
  int recompile_bit = (trap_state & DS_RECOMPILE_BIT);
  trap_state -= recompile_bit;
  if (trap_state == DS_REASON_MASK) {
    return -1;  // true, unspecifically (bottom of state lattice)
  } else if (trap_state == reason) {
    return 1;   // true, definitely
  } else if (trap_state == 0) {
    return 0;   // false, definitely (top of state lattice)
  } else {
    return 0;   // false, definitely
  }
}
//-------------------------trap_state_add_reason-------------------------------
int Deoptimization::trap_state_add_reason(int trap_state, int reason) {
  assert(reason_is_recorded_per_bytecode((DeoptReason)reason) || reason == Reason_many, "valid reason");
  int recompile_bit = (trap_state & DS_RECOMPILE_BIT);
  trap_state -= recompile_bit;
  if (trap_state == DS_REASON_MASK) {
    return trap_state + recompile_bit;     // already at state lattice bottom
  } else if (trap_state == reason) {
    return trap_state + recompile_bit;     // the condition is already true
  } else if (trap_state == 0) {
    return reason + recompile_bit;          // no condition has yet been true
  } else {
    return DS_REASON_MASK + recompile_bit;  // fall to state lattice bottom
  }
}
//-----------------------trap_state_is_recompiled------------------------------
bool Deoptimization::trap_state_is_recompiled(int trap_state) {
  return (trap_state & DS_RECOMPILE_BIT) != 0;
}
//-----------------------trap_state_set_recompiled-----------------------------
int Deoptimization::trap_state_set_recompiled(int trap_state, bool z) {
  if (z)  return trap_state |  DS_RECOMPILE_BIT;
  else    return trap_state & ~DS_RECOMPILE_BIT;
}
//---------------------------format_trap_state---------------------------------
// This is used for debugging and diagnostics, including hotspot.log output.
const char* Deoptimization::format_trap_state(char* buf, size_t buflen,
                                              int trap_state) {
  DeoptReason reason      = trap_state_reason(trap_state);
  bool        recomp_flag = trap_state_is_recompiled(trap_state);
  // Re-encode the state from its decoded components.
  int decoded_state = 0;
  if (reason_is_recorded_per_bytecode(reason) || reason == Reason_many)
    decoded_state = trap_state_add_reason(decoded_state, reason);
  if (recomp_flag)
    decoded_state = trap_state_set_recompiled(decoded_state, recomp_flag);
  // If the state re-encodes properly, format it symbolically.
  // Because this routine is used for debugging and diagnostics,
  // be robust even if the state is a strange value.
  size_t len;
  if (decoded_state != trap_state) {
    // Random buggy state that doesn't decode??
    len = jio_snprintf(buf, buflen, "#%d", trap_state);
  } else {
    len = jio_snprintf(buf, buflen, "%s%s",
                       trap_reason_name(reason),
                       recomp_flag ? " recompiled" : "");
  }
  if (len >= buflen)
    buf[buflen-1] = '\0';
  return buf;
}


//--------------------------------statics--------------------------------------
Deoptimization::DeoptAction Deoptimization::_unloaded_action
  = Deoptimization::Action_reinterpret;
const char* Deoptimization::_trap_reason_name[Reason_LIMIT] = {
  // Note:  Keep this in sync. with enum DeoptReason.
  "none",
  "null_check",
  "null_assert",
  "range_check",
  "class_check",
  "array_check",
  "intrinsic",
  "unloaded",
  "uninitialized",
  "unreached",
  "unhandled",
  "constraint",
  "div0_check",
  "age"
};
const char* Deoptimization::_trap_action_name[Action_LIMIT] = {
  // Note:  Keep this in sync. with enum DeoptAction.
  "none",
  "maybe_recompile",
  "reinterpret",
  "make_not_entrant",
  "make_not_compilable"
};

const char* Deoptimization::trap_reason_name(int reason) {
  if (reason == Reason_many)  return "many";
  if ((uint)reason < Reason_LIMIT)
    return _trap_reason_name[reason];
  static char buf[20];
  sprintf(buf, "reason%d", reason);
  return buf;
}
const char* Deoptimization::trap_action_name(int action) {
  if ((uint)action < Action_LIMIT)
    return _trap_action_name[action];
  static char buf[20];
  sprintf(buf, "action%d", action);
  return buf;
}

// This is used for debugging and diagnostics, including hotspot.log output.
const char* Deoptimization::format_trap_request(char* buf, size_t buflen,
                                                int trap_request) {
  jint unloaded_class_index = trap_request_index(trap_request);
  const char* reason = trap_reason_name(trap_request_reason(trap_request));
  const char* action = trap_action_name(trap_request_action(trap_request));
  size_t len;
  if (unloaded_class_index < 0) {
    len = jio_snprintf(buf, buflen, "reason='%s' action='%s'",
                       reason, action);
  } else {
    len = jio_snprintf(buf, buflen, "reason='%s' action='%s' index='%d'",
                       reason, action, unloaded_class_index);
  }
  if (len >= buflen)
    buf[buflen-1] = '\0';
  return buf;
}

juint Deoptimization::_deoptimization_hist
        [Deoptimization::Reason_LIMIT]
    [1 + Deoptimization::Action_LIMIT]
        [Deoptimization::BC_CASE_LIMIT]
  = {0};

enum {
  LSB_BITS = 8,
  LSB_MASK = right_n_bits(LSB_BITS)
};

void Deoptimization::gather_statistics(DeoptReason reason, DeoptAction action,
                                       Bytecodes::Code bc) {
  assert(reason >= 0 && reason < Reason_LIMIT, "oob");
  assert(action >= 0 && action < Action_LIMIT, "oob");
  _deoptimization_hist[Reason_none][0][0] += 1;  // total
  _deoptimization_hist[reason][0][0]      += 1;  // per-reason total
  juint* cases = _deoptimization_hist[reason][1+action];
  juint* bc_counter_addr = NULL;
  juint  bc_counter      = 0;
  // Look for an unused counter, or an exact match to this BC.
  if (bc != Bytecodes::_illegal) {
    for (int bc_case = 0; bc_case < BC_CASE_LIMIT; bc_case++) {
      juint* counter_addr = &cases[bc_case];
      juint  counter = *counter_addr;
      if ((counter == 0 && bc_counter_addr == NULL)
          || (Bytecodes::Code)(counter & LSB_MASK) == bc) {
        // this counter is either free or is already devoted to this BC
        bc_counter_addr = counter_addr;
        bc_counter = counter | bc;
      }
    }
  }
  if (bc_counter_addr == NULL) {
    // Overflow, or no given bytecode.
    bc_counter_addr = &cases[BC_CASE_LIMIT-1];
    bc_counter = (*bc_counter_addr & ~LSB_MASK);  // clear LSB
  }
  *bc_counter_addr = bc_counter + (1 << LSB_BITS);
}

jint Deoptimization::total_deoptimization_count() {
  return _deoptimization_hist[Reason_none][0][0];
}

jint Deoptimization::deoptimization_count(DeoptReason reason) {
  assert(reason >= 0 && reason < Reason_LIMIT, "oob");
  return _deoptimization_hist[reason][0][0];
}

void Deoptimization::print_statistics() {
  juint total = total_deoptimization_count();
  juint account = total;
  if (total != 0) {
    ttyLocker ttyl;
    if (xtty != NULL)  xtty->head("statistics type='deoptimization'");
    tty->print_cr("Deoptimization traps recorded:");
    #define PRINT_STAT_LINE(name, r) \
      tty->print_cr("  %4d (%4.1f%%) %s", (int)(r), ((r) * 100.0) / total, name);
    PRINT_STAT_LINE("total", total);
    // For each non-zero entry in the histogram, print the reason,
    // the action, and (if specifically known) the type of bytecode.
    for (int reason = 0; reason < Reason_LIMIT; reason++) {
      for (int action = 0; action < Action_LIMIT; action++) {
        juint* cases = _deoptimization_hist[reason][1+action];
        for (int bc_case = 0; bc_case < BC_CASE_LIMIT; bc_case++) {
          juint counter = cases[bc_case];
          if (counter != 0) {
            char name[1*K];
            Bytecodes::Code bc = (Bytecodes::Code)(counter & LSB_MASK);
            if (bc_case == BC_CASE_LIMIT && (int)bc == 0)
              bc = Bytecodes::_illegal;
            sprintf(name, "%s/%s/%s",
                    trap_reason_name(reason),
                    trap_action_name(action),
                    Bytecodes::is_defined(bc)? Bytecodes::name(bc): "other");
            juint r = counter >> LSB_BITS;
            tty->print_cr("  %40s: " UINT32_FORMAT " (%.1f%%)", name, r, (r * 100.0) / total);
            account -= r;
          }
        }
      }
    }
    if (account != 0) {
      PRINT_STAT_LINE("unaccounted", account);
    }
    #undef PRINT_STAT_LINE
    if (xtty != NULL)  xtty->tail("statistics");
  }
}
#else // COMPILER2


// Stubs for C1 only system.
bool Deoptimization::trap_state_is_recompiled(int trap_state) {
  return false;
}

const char* Deoptimization::trap_reason_name(int reason) {
  return "unknown";
}

void Deoptimization::print_statistics() {
  // no output
}

void
Deoptimization::update_method_data_from_interpreter(methodDataHandle trap_mdo, int trap_bci, int reason) {
  // no udpate
}

int Deoptimization::trap_state_has_reason(int trap_state, int reason) {
  return 0;
}

void Deoptimization::gather_statistics(DeoptReason reason, DeoptAction action,
                                       Bytecodes::Code bc) {
  // no update
}

const char* Deoptimization::format_trap_state(char* buf, size_t buflen,
                                              int trap_state) {
  jio_snprintf(buf, buflen, "#%d", trap_state);
  return buf;
}

#endif // COMPILER2