view src/share/vm/prims/methodHandleWalk.cpp @ 1133:aa62b9388fce

6894206: JVM needs a way to traverse method handle structures Summary: We need a way to walk chained method handles in the JVM to call the right methods and to generate required bytecode adapters for the compilers. Reviewed-by: kvn
author twisti
date Mon, 04 Jan 2010 15:52:40 +0100
parents
children dd57230ba8fe
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/*
 * Copyright 2008-2010 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.
 *
 */

/*
 * JSR 292 reference implementation: method handle structure analysis
 */

#include "incls/_precompiled.incl"
#include "incls/_methodHandleWalk.cpp.incl"

void MethodHandleChain::set_method_handle(Handle mh, TRAPS) {
  if (!java_dyn_MethodHandle::is_instance(mh()))  lose("bad method handle", CHECK);

  // set current method handle and unpack partially
  _method_handle = mh;
  _is_last       = false;
  _is_bound      = false;
  _arg_slot      = -1;
  _arg_type      = T_VOID;
  _conversion    = -1;
  _last_invoke   = Bytecodes::_nop;  //arbitrary non-garbage

  if (sun_dyn_DirectMethodHandle::is_instance(mh())) {
    set_last_method(mh(), THREAD);
    return;
  }
  if (sun_dyn_AdapterMethodHandle::is_instance(mh())) {
    _conversion = AdapterMethodHandle_conversion();
    assert(_conversion != -1, "bad conv value");
    assert(sun_dyn_BoundMethodHandle::is_instance(mh()), "also BMH");
  }
  if (sun_dyn_BoundMethodHandle::is_instance(mh())) {
    if (!is_adapter())          // keep AMH and BMH separate in this model
      _is_bound = true;
    _arg_slot = BoundMethodHandle_vmargslot();
    oop target = MethodHandle_vmtarget_oop();
    if (!is_bound() || java_dyn_MethodHandle::is_instance(target)) {
      _arg_type = compute_bound_arg_type(target, NULL, _arg_slot, CHECK);
    } else if (target != NULL && target->is_method()) {
      _arg_type = compute_bound_arg_type(NULL, (methodOop)target, _arg_slot, CHECK);
      set_last_method(mh(), CHECK);
    } else {
      _is_bound = false;  // lose!
    }
  }
  if (is_bound() && _arg_type == T_VOID) {
    lose("bad vmargslot", CHECK);
  }
  if (!is_bound() && !is_adapter()) {
    lose("unrecognized MH type", CHECK);
  }
}

void MethodHandleChain::set_last_method(oop target, TRAPS) {
  _is_last = true;
  klassOop receiver_limit_oop = NULL;
  int flags = 0;
  methodOop m = MethodHandles::decode_method(target, receiver_limit_oop, flags);
  _last_method = methodHandle(THREAD, m);
  if ((flags & MethodHandles::_dmf_has_receiver) == 0)
    _last_invoke = Bytecodes::_invokestatic;
  else if ((flags & MethodHandles::_dmf_does_dispatch) == 0)
    _last_invoke = Bytecodes::_invokespecial;
  else if ((flags & MethodHandles::_dmf_from_interface) != 0)
    _last_invoke = Bytecodes::_invokeinterface;
  else
    _last_invoke = Bytecodes::_invokevirtual;
}

BasicType MethodHandleChain::compute_bound_arg_type(oop target, methodOop m, int arg_slot, TRAPS) {
  // There is no direct indication of whether the argument is primitive or not.
  // It is implied by the _vmentry code, and by the MethodType of the target.
  // FIXME: Make it explicit MethodHandleImpl refactors out from MethodHandle
  BasicType arg_type = T_VOID;
  if (target != NULL) {
    oop mtype = java_dyn_MethodHandle::type(target);
    int arg_num = MethodHandles::argument_slot_to_argnum(mtype, arg_slot);
    if (arg_num >= 0) {
      oop ptype = java_dyn_MethodType::ptype(mtype, arg_num);
      arg_type = java_lang_Class::as_BasicType(ptype);
    }
  } else if (m != NULL) {
    // figure out the argument type from the slot
    // FIXME: make this explicit in the MH
    int cur_slot = m->size_of_parameters();
    if (arg_slot >= cur_slot)
      return T_VOID;
    if (!m->is_static()) {
      cur_slot -= type2size[T_OBJECT];
      if (cur_slot == arg_slot)
        return T_OBJECT;
    }
    for (SignatureStream ss(m->signature()); !ss.is_done(); ss.next()) {
      BasicType bt = ss.type();
      cur_slot -= type2size[bt];
      if (cur_slot <= arg_slot) {
        if (cur_slot == arg_slot)
          arg_type = bt;
        break;
      }
    }
  }
  if (arg_type == T_ARRAY)
    arg_type = T_OBJECT;
  return arg_type;
}

void MethodHandleChain::lose(const char* msg, TRAPS) {
  _lose_message = msg;
  if (!THREAD->is_Java_thread() || ((JavaThread*)THREAD)->thread_state() != _thread_in_vm) {
    // throw a preallocated exception
    THROW_OOP(Universe::virtual_machine_error_instance());
  }
  THROW_MSG(vmSymbols::java_lang_InternalError(), msg);
}

Bytecodes::Code MethodHandleWalker::conversion_code(BasicType src, BasicType dest) {
  if (is_subword_type(src)) {
    src = T_INT;          // all subword src types act like int
  }
  if (src == dest) {
    return Bytecodes::_nop;
  }

#define SRC_DEST(s,d) (((int)(s) << 4) + (int)(d))
  switch (SRC_DEST(src, dest)) {
  case SRC_DEST(T_INT, T_LONG):           return Bytecodes::_i2l;
  case SRC_DEST(T_INT, T_FLOAT):          return Bytecodes::_i2f;
  case SRC_DEST(T_INT, T_DOUBLE):         return Bytecodes::_i2d;
  case SRC_DEST(T_INT, T_BYTE):           return Bytecodes::_i2b;
  case SRC_DEST(T_INT, T_CHAR):           return Bytecodes::_i2c;
  case SRC_DEST(T_INT, T_SHORT):          return Bytecodes::_i2s;

  case SRC_DEST(T_LONG, T_INT):           return Bytecodes::_l2i;
  case SRC_DEST(T_LONG, T_FLOAT):         return Bytecodes::_l2f;
  case SRC_DEST(T_LONG, T_DOUBLE):        return Bytecodes::_l2d;

  case SRC_DEST(T_FLOAT, T_INT):          return Bytecodes::_f2i;
  case SRC_DEST(T_FLOAT, T_LONG):         return Bytecodes::_f2l;
  case SRC_DEST(T_FLOAT, T_DOUBLE):       return Bytecodes::_f2d;

  case SRC_DEST(T_DOUBLE, T_INT):         return Bytecodes::_d2i;
  case SRC_DEST(T_DOUBLE, T_LONG):        return Bytecodes::_d2l;
  case SRC_DEST(T_DOUBLE, T_FLOAT):       return Bytecodes::_d2f;
  }
#undef SRC_DEST

  // cannot do it in one step, or at all
  return Bytecodes::_illegal;
}

MethodHandleWalker::ArgToken
MethodHandleWalker::walk(TRAPS) {
  walk_incoming_state(CHECK_NULL);

  for (;;) {
    set_method_handle(chain().method_handle_oop());

    assert(_outgoing_argc == argument_count_slow(), "empty slots under control");

    if (chain().is_adapter()) {
      int conv_op = chain().adapter_conversion_op();
      int arg_slot = chain().adapter_arg_slot();
      SlotState* arg_state = slot_state(arg_slot);
      if (arg_state == NULL
          && conv_op > sun_dyn_AdapterMethodHandle::OP_RETYPE_RAW) {
        lose("bad argument index", CHECK_NULL);
      }

      // perform the adapter action
      switch (chain().adapter_conversion_op()) {
      case sun_dyn_AdapterMethodHandle::OP_RETYPE_ONLY:
      case sun_dyn_AdapterMethodHandle::OP_RETYPE_RAW:
        // No changes to arguments; pass the bits through.
        // The only difference between the two ops is that the "only" version
        // is fully compatible with the verifier, while the "raw" version
        // performs a few extra bitwise conversions (like long <-> double).
        break;

      case sun_dyn_AdapterMethodHandle::OP_CHECK_CAST: {
        // checkcast the Nth outgoing argument in place
        klassOop dest_klass = NULL;
        BasicType dest = java_lang_Class::as_BasicType(chain().adapter_arg_oop(), &dest_klass);
        assert(dest == T_OBJECT, "");
        assert(dest == arg_state->_type, "");
        arg_state->_arg = make_conversion(T_OBJECT, dest_klass, Bytecodes::_checkcast, arg_state->_arg, CHECK_NULL);
        debug_only(dest_klass = (klassOop)badOop);
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_PRIM_TO_PRIM: {
        // i2l, etc., on the Nth outgoing argument in place
        BasicType src = chain().adapter_conversion_src_type(),
                  dest = chain().adapter_conversion_dest_type();
        Bytecodes::Code bc = conversion_code(src, dest);
        ArgToken arg = arg_state->_arg;
        if (bc == Bytecodes::_nop) {
          break;
        } else if (bc != Bytecodes::_illegal) {
          arg = make_conversion(dest, NULL, bc, arg, CHECK_NULL);
        } else if (is_subword_type(dest)) {
          bc = conversion_code(src, T_INT);
          if (bc != Bytecodes::_illegal) {
            arg = make_conversion(dest, NULL, bc, arg, CHECK_NULL);
            bc = conversion_code(T_INT, dest);
            arg = make_conversion(dest, NULL, bc, arg, CHECK_NULL);
          }
        }
        if (bc == Bytecodes::_illegal) {
          lose("bad primitive conversion", CHECK_NULL);
        }
        change_argument(src, arg_slot, dest, arg);
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_REF_TO_PRIM: {
        // checkcast to wrapper type & call intValue, etc.
        BasicType dest = chain().adapter_conversion_dest_type();
        ArgToken arg = arg_state->_arg;
        arg = make_conversion(T_OBJECT, SystemDictionary::box_klass(dest),
                              Bytecodes::_checkcast, arg, CHECK_NULL);
        vmIntrinsics::ID unboxer = vmIntrinsics::for_unboxing(dest);
        if (unboxer == vmIntrinsics::_none) {
          lose("no unboxing method", CHECK_NULL);
        }
        ArgToken arglist[2];
        arglist[0] = arg;       // outgoing 'this'
        arglist[1] = NULL;      // sentinel
        arg = make_invoke(NULL, unboxer, Bytecodes::_invokevirtual, false, 1, &arglist[0], CHECK_NULL);
        change_argument(T_OBJECT, arg_slot, dest, arg);
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_PRIM_TO_REF: {
        // call wrapper type.valueOf
        BasicType src = chain().adapter_conversion_src_type();
        ArgToken arg = arg_state->_arg;
        vmIntrinsics::ID boxer = vmIntrinsics::for_boxing(src);
        if (boxer == vmIntrinsics::_none) {
          lose("no boxing method", CHECK_NULL);
        }
        ArgToken arglist[2];
        arglist[0] = arg;       // outgoing value
        arglist[1] = NULL;      // sentinel
        arg = make_invoke(NULL, boxer, Bytecodes::_invokevirtual, false, 1, &arglist[0], CHECK_NULL);
        change_argument(src, arg_slot, T_OBJECT, arg);
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_SWAP_ARGS: {
        int dest_arg_slot = chain().adapter_conversion_vminfo();
        if (!slot_has_argument(dest_arg_slot)) {
          lose("bad swap index", CHECK_NULL);
        }
        // a simple swap between two arguments
        SlotState* dest_arg_state = slot_state(dest_arg_slot);
        SlotState temp = (*dest_arg_state);
        (*dest_arg_state) = (*arg_state);
        (*arg_state) = temp;
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_ROT_ARGS: {
        int dest_arg_slot = chain().adapter_conversion_vminfo();
        if (!slot_has_argument(dest_arg_slot) || arg_slot == dest_arg_slot) {
          lose("bad rotate index", CHECK_NULL);
        }
        SlotState* dest_arg_state = slot_state(dest_arg_slot);
        // Rotate the source argument (plus following N slots) into the
        // position occupied by the dest argument (plus following N slots).
        int rotate_count = type2size[dest_arg_state->_type];
        // (no other rotate counts are currently supported)
        if (arg_slot < dest_arg_slot) {
          for (int i = 0; i < rotate_count; i++) {
            SlotState temp = _outgoing.at(arg_slot);
            _outgoing.remove_at(arg_slot);
            _outgoing.insert_before(dest_arg_slot + rotate_count - 1, temp);
          }
        } else { // arg_slot > dest_arg_slot
          for (int i = 0; i < rotate_count; i++) {
            SlotState temp = _outgoing.at(arg_slot + rotate_count - 1);
            _outgoing.remove_at(arg_slot + rotate_count - 1);
            _outgoing.insert_before(dest_arg_slot, temp);
          }
        }
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_DUP_ARGS: {
        int dup_slots = chain().adapter_conversion_stack_pushes();
        if (dup_slots <= 0) {
          lose("bad dup count", CHECK_NULL);
        }
        for (int i = 0; i < dup_slots; i++) {
          SlotState* dup = slot_state(arg_slot + 2*i);
          if (dup == NULL)              break;  // safety net
          if (dup->_type != T_VOID)     _outgoing_argc += 1;
          _outgoing.insert_before(i, (*dup));
        }
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_DROP_ARGS: {
        int drop_slots = -chain().adapter_conversion_stack_pushes();
        if (drop_slots <= 0) {
          lose("bad drop count", CHECK_NULL);
        }
        for (int i = 0; i < drop_slots; i++) {
          SlotState* drop = slot_state(arg_slot);
          if (drop == NULL)             break;  // safety net
          if (drop->_type != T_VOID)    _outgoing_argc -= 1;
          _outgoing.remove_at(arg_slot);
        }
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_COLLECT_ARGS: { //NYI, may GC
        lose("unimplemented", CHECK_NULL);
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_SPREAD_ARGS: {
        klassOop array_klass_oop = NULL;
        BasicType array_type = java_lang_Class::as_BasicType(chain().adapter_arg_oop(),
                                                             &array_klass_oop);
        assert(array_type == T_OBJECT, "");
        assert(Klass::cast(array_klass_oop)->oop_is_array(), "");
        arrayKlassHandle array_klass(THREAD, array_klass_oop);
        debug_only(array_klass_oop = (klassOop)badOop);

        klassOop element_klass_oop = NULL;
        BasicType element_type = java_lang_Class::as_BasicType(array_klass->component_mirror(),
                                                               &element_klass_oop);
        KlassHandle element_klass(THREAD, element_klass_oop);
        debug_only(element_klass_oop = (klassOop)badOop);

        // Fetch the argument, which we will cast to the required array type.
        assert(arg_state->_type == T_OBJECT, "");
        ArgToken array_arg = arg_state->_arg;
        array_arg = make_conversion(T_OBJECT, array_klass(), Bytecodes::_checkcast, array_arg, CHECK_NULL);
        change_argument(T_OBJECT, arg_slot, T_VOID, NULL);

        // Check the required length.
        int spread_slots = 1 + chain().adapter_conversion_stack_pushes();
        int spread_length = spread_slots;
        if (type2size[element_type] == 2) {
          if (spread_slots % 2 != 0)  spread_slots = -1;  // force error
          spread_length = spread_slots / 2;
        }
        if (spread_slots < 0) {
          lose("bad spread length", CHECK_NULL);
        }

        jvalue   length_jvalue;  length_jvalue.i = spread_length;
        ArgToken length_arg = make_prim_constant(T_INT, &length_jvalue, CHECK_NULL);
        // Call a built-in method known to the JVM to validate the length.
        ArgToken arglist[3];
        arglist[0] = array_arg;  // value to check
        arglist[1] = length_arg; // length to check
        arglist[2] = NULL;       // sentinel
        make_invoke(NULL, vmIntrinsics::_checkSpreadArgument,
                    Bytecodes::_invokestatic, false, 3, &arglist[0], CHECK_NULL);

        // Spread out the array elements.
        Bytecodes::Code aload_op = Bytecodes::_aaload;
        if (element_type != T_OBJECT) {
          lose("primitive array NYI", CHECK_NULL);
        }
        int ap = arg_slot;
        for (int i = 0; i < spread_length; i++) {
          jvalue   offset_jvalue;  offset_jvalue.i = i;
          ArgToken offset_arg = make_prim_constant(T_INT, &offset_jvalue, CHECK_NULL);
          ArgToken element_arg = make_fetch(element_type, element_klass(), aload_op, array_arg, offset_arg, CHECK_NULL);
          change_argument(T_VOID, ap, element_type, element_arg);
          ap += type2size[element_type];
        }
        break;
      }

      case sun_dyn_AdapterMethodHandle::OP_FLYBY: //NYI, runs Java code
      case sun_dyn_AdapterMethodHandle::OP_RICOCHET: //NYI, runs Java code
        lose("unimplemented", CHECK_NULL);
        break;

      default:
        lose("bad adapter conversion", CHECK_NULL);
        break;
      }
    }

    if (chain().is_bound()) {
      // push a new argument
      BasicType arg_type  = chain().bound_arg_type();
      jint      arg_slot  = chain().bound_arg_slot();
      oop       arg_oop   = chain().bound_arg_oop();
      ArgToken  arg       = NULL;
      if (arg_type == T_OBJECT) {
        arg = make_oop_constant(arg_oop, CHECK_NULL);
      } else {
        jvalue arg_value;
        BasicType bt = java_lang_boxing_object::get_value(arg_oop, &arg_value);
        if (bt == arg_type) {
          arg = make_prim_constant(arg_type, &arg_value, CHECK_NULL);
        } else {
          lose("bad bound value", CHECK_NULL);
        }
      }
      debug_only(arg_oop = badOop);
      change_argument(T_VOID, arg_slot, arg_type, arg);
    }

    // this test must come after the body of the loop
    if (!chain().is_last()) {
      chain().next(CHECK_NULL);
    } else {
      break;
    }
  }

  // finish the sequence with a tail-call to the ultimate target
  // parameters are passed in logical order (recv 1st), not slot order
  ArgToken* arglist = NEW_RESOURCE_ARRAY(ArgToken, _outgoing.length() + 1);
  int ap = 0;
  for (int i = _outgoing.length() - 1; i >= 0; i--) {
    SlotState* arg_state = slot_state(i);
    if (arg_state->_type == T_VOID)  continue;
    arglist[ap++] = _outgoing.at(i)._arg;
  }
  assert(ap == _outgoing_argc, "");
  arglist[ap] = NULL; // add a sentinel, for the sake of asserts
  return make_invoke(chain().last_method_oop(),
                     vmIntrinsics::_none,
                     chain().last_invoke_code(), true,
                     ap, arglist, THREAD);
}

void MethodHandleWalker::walk_incoming_state(TRAPS) {
  Handle mtype(THREAD, chain().method_type_oop());
  int nptypes = java_dyn_MethodType::ptype_count(mtype());
  _outgoing_argc = nptypes;
  int argp = nptypes - 1;
  if (argp >= 0) {
    _outgoing.at_grow(argp, make_state(T_VOID, NULL)); // presize
  }
  for (int i = 0; i < nptypes; i++) {
    klassOop  arg_type_klass = NULL;
    BasicType arg_type = java_lang_Class::as_BasicType(
                java_dyn_MethodType::ptype(mtype(), i), &arg_type_klass);
    ArgToken  arg = make_parameter(arg_type, arg_type_klass, i, CHECK);
    debug_only(arg_type_klass = (klassOop)NULL);
    _outgoing.at_put(argp, make_state(arg_type, arg));
    if (type2size[arg_type] == 2) {
      // add the extra slot, so we can model the JVM stack
      _outgoing.insert_before(argp+1, make_state(T_VOID, NULL));
    }
    --argp;
  }
  // call make_parameter at the end of the list for the return type
  klassOop  ret_type_klass = NULL;
  BasicType ret_type = java_lang_Class::as_BasicType(
              java_dyn_MethodType::rtype(mtype()), &ret_type_klass);
  ArgToken  ret = make_parameter(ret_type, ret_type_klass, -1, CHECK);
  // ignore ret; client can catch it if needed
}

// this is messy because some kinds of arguments are paired with
// companion slots containing an empty value
void MethodHandleWalker::change_argument(BasicType old_type, int slot, BasicType new_type,
                                         MethodHandleWalker::ArgToken new_arg) {
  int old_size = type2size[old_type];
  int new_size = type2size[new_type];
  if (old_size == new_size) {
    // simple case first
    _outgoing.at_put(slot, make_state(new_type, new_arg));
  } else if (old_size > new_size) {
    for (int i = old_size-1; i >= new_size; i++) {
      assert((i != 0) == (_outgoing.at(slot + i)._type == T_VOID), "");
      _outgoing.remove_at(slot + i);
    }
    if (new_size > 0)
      _outgoing.at_put(slot, make_state(new_type, new_arg));
    else
      _outgoing_argc -= 1;      // deleted a real argument
  } else {
    for (int i = old_size; i < new_size; i++) {
      _outgoing.insert_before(slot+i, make_state(T_VOID, NULL));
    }
    _outgoing.at_put(slot, make_state(new_type, new_arg));
    if (old_size == 0)
      _outgoing_argc += 1;      // inserted a real argument
  }
}


#ifdef ASSERT
int MethodHandleWalker::argument_count_slow() {
  int args_seen = 0;
  for (int i = _outgoing.length() - 1; i >= 0; i--) {
    if (_outgoing.at(i)._type != T_VOID) {
      ++args_seen;
    }
  }
  return args_seen;
}
#endif


void MethodHandleCompiler::compile(TRAPS) {
  assert(_thread == THREAD, "must be same thread");

  _constant_oops.append(Handle());  // element zero is always the null constant
  _constant_prims.append(NULL);
  {
    symbolOop sig
      = java_dyn_MethodType::as_signature(chain().method_type_oop(), true, CHECK);
    _signature_index = find_oop_constant(sig);
    assert(signature() == sig, "");
  }

  walk(CHECK);
}

MethodHandleWalker::ArgToken
MethodHandleCompiler::make_conversion(BasicType type, klassOop tk, Bytecodes::Code op,
                                      MethodHandleWalker::ArgToken src, TRAPS) {
  Unimplemented();
  return NULL;
}

MethodHandleWalker::ArgToken
MethodHandleCompiler::make_invoke(methodOop m, vmIntrinsics::ID iid,
                                  Bytecodes::Code op, bool tailcall,
                                  int argc, MethodHandleWalker::ArgToken* argv,
                                  TRAPS) {
  // If tailcall, we have walked all the way to a direct method handle.
  // Otherwise, make a recursive call to some helper routine.
#ifdef ASSERT
  switch (op) {
  case Bytecodes::_invokevirtual:
  case Bytecodes::_invokespecial:
  case Bytecodes::_invokestatic:
  case Bytecodes::_invokeinterface:
    break;
  default:
    ShouldNotReachHere();
  }
#endif //ASSERT
  _bytes.put((char) op);

  Unimplemented();
  return NULL;
}

MethodHandleWalker::ArgToken
MethodHandleCompiler::make_fetch(BasicType type, klassOop tk, Bytecodes::Code op,
                                 MethodHandleWalker::ArgToken base,
                                 MethodHandleWalker::ArgToken offset,
                                 TRAPS) {
  Unimplemented();
  return NULL;
}

int MethodHandleCompiler::find_oop_constant(oop con) {
  if (con == NULL)  return 0;
  for (int i = 1, imax = _constant_oops.length(); i < imax; i++) {
    if (_constant_oops.at(i) == con)
      return i;
  }
  _constant_prims.append(NULL);
  return _constant_oops.append(con);
}

int MethodHandleCompiler::find_prim_constant(BasicType bt, jvalue* con) {
  jvalue con_copy;
  assert(bt < T_OBJECT, "");
  if (type2aelembytes(bt) < jintSize) {
    // widen to int
    con_copy = (*con);
    con = &con_copy;
    switch (bt) {
    case T_BOOLEAN: con->i = (con->z ? 1 : 0); break;
    case T_BYTE:    con->i = con->b;           break;
    case T_CHAR:    con->i = con->c;           break;
    case T_SHORT:   con->i = con->s;           break;
    default: ShouldNotReachHere();
    }
    bt = T_INT;
  }
  for (int i = 1, imax = _constant_prims.length(); i < imax; i++) {
    PrimCon* pcon = _constant_prims.at(i);
    if (pcon != NULL && pcon->_type == bt) {
      bool match = false;
      switch (type2size[bt]) {
      case 1:  if (pcon->_value.i == con->i)  match = true;  break;
      case 2:  if (pcon->_value.j == con->j)  match = true;  break;
      }
      if (match)
        return i;
    }
  }
  PrimCon* pcon = new PrimCon();
  pcon->_type = bt;
  pcon->_value = (*con);
  _constant_oops.append(Handle());
  return _constant_prims.append(pcon);
}


#ifndef PRODUCT

// MH printer for debugging.

class MethodHandlePrinter : public MethodHandleWalker {
private:
  outputStream* _out;
  bool          _verbose;
  int           _temp_num;
  stringStream  _strbuf;
  const char* strbuf() {
    const char* s = _strbuf.as_string();
    _strbuf.reset();
    return s;
  }
  ArgToken token(const char* str) {
    return (ArgToken) str;
  }
  void start_params() {
    _out->print("(");
  }
  void end_params() {
    if (_verbose)  _out->print("\n");
    _out->print(") => {");
  }
  void put_type_name(BasicType type, klassOop tk, outputStream* s) {
    const char* kname = NULL;
    if (tk != NULL)
      kname = Klass::cast(tk)->external_name();
    s->print("%s", (kname != NULL) ? kname : type2name(type));
  }
  ArgToken maybe_make_temp(const char* statement_op, BasicType type, const char* temp_name) {
    const char* value = strbuf();
    if (!_verbose)  return token(value);
    // make an explicit binding for each separate value
    _strbuf.print("%s%d", temp_name, ++_temp_num);
    const char* temp = strbuf();
    _out->print("\n  %s %s %s = %s;", statement_op, type2name(type), temp, value);
    return token(temp);
  }

public:
  MethodHandlePrinter(Handle root, bool verbose, outputStream* out, TRAPS)
    : MethodHandleWalker(root, THREAD),
      _out(out),
      _verbose(verbose),
      _temp_num(0)
  {
    start_params();
  }
  virtual ArgToken make_parameter(BasicType type, klassOop tk, int argnum, TRAPS) {
    if (argnum < 0) {
      end_params();
      return NULL;
    }
    if (argnum == 0) {
      _out->print(_verbose ? "\n  " : "");
    } else {
      _out->print(_verbose ? ",\n  " : ", ");
    }
    if (argnum >= _temp_num)
      _temp_num = argnum;
    // generate an argument name
    _strbuf.print("a%d", argnum);
    const char* arg = strbuf();
    put_type_name(type, tk, _out);
    _out->print(" %s", arg);
    return token(arg);
  }
  virtual ArgToken make_oop_constant(oop con, TRAPS) {
    if (con == NULL)
      _strbuf.print("null");
    else
      con->print_value_on(&_strbuf);
    if (_strbuf.size() == 0) {  // yuck
      _strbuf.print("(a ");
      put_type_name(T_OBJECT, con->klass(), &_strbuf);
      _strbuf.print(")");
    }
    return maybe_make_temp("constant", T_OBJECT, "k");
  }
  virtual ArgToken make_prim_constant(BasicType type, jvalue* con, TRAPS) {
    java_lang_boxing_object::print(type, con, &_strbuf);
    return maybe_make_temp("constant", type, "k");
  }
  virtual ArgToken make_conversion(BasicType type, klassOop tk, Bytecodes::Code op, ArgToken src, TRAPS) {
    _strbuf.print("%s(%s", Bytecodes::name(op), (const char*)src);
    if (tk != NULL) {
      _strbuf.print(", ");
      put_type_name(type, tk, &_strbuf);
    }
    _strbuf.print(")");
    return maybe_make_temp("convert", type, "v");
  }
  virtual ArgToken make_fetch(BasicType type, klassOop tk, Bytecodes::Code op, ArgToken base, ArgToken offset, TRAPS) {
    _strbuf.print("%s(%s, %s", Bytecodes::name(op), (const char*)base, (const char*)offset);
    if (tk != NULL) {
      _strbuf.print(", ");
      put_type_name(type, tk, &_strbuf);
    }
    _strbuf.print(")");
    return maybe_make_temp("fetch", type, "x");
  }
  virtual ArgToken make_invoke(methodOop m, vmIntrinsics::ID iid,
                               Bytecodes::Code op, bool tailcall,
                               int argc, ArgToken* argv, TRAPS) {
    symbolOop name, sig;
    if (m != NULL) {
      name = m->name();
      sig  = m->signature();
    } else {
      name = vmSymbols::symbol_at(vmIntrinsics::name_for(iid));
      sig  = vmSymbols::symbol_at(vmIntrinsics::signature_for(iid));
    }
    _strbuf.print("%s %s%s(", Bytecodes::name(op), name->as_C_string(), sig->as_C_string());
    for (int i = 0; i < argc; i++) {
      _strbuf.print("%s%s", (i > 0 ? ", " : ""), (const char*)argv[i]);
    }
    _strbuf.print(")");
    if (!tailcall) {
      BasicType rt = char2type(sig->byte_at(sig->utf8_length()-1));
      if (rt == T_ILLEGAL)  rt = T_OBJECT;  // ';' at the end of '(...)L...;'
      return maybe_make_temp("invoke", rt, "x");
    } else {
      const char* ret = strbuf();
      _out->print(_verbose ? "\n  return " : " ");
      _out->print("%s", ret);
      _out->print(_verbose ? "\n}\n" : " }");
    }
    return ArgToken();
  }

  virtual void set_method_handle(oop mh) {
    if (WizardMode && Verbose) {
      tty->print("\n--- next target: ");
      mh->print();
    }
  }

  static void print(Handle root, bool verbose, outputStream* out, TRAPS) {
    ResourceMark rm;
    MethodHandlePrinter printer(root, verbose, out, CHECK);
    printer.walk(CHECK);
    out->print("\n");
  }
  static void print(Handle root, bool verbose = Verbose, outputStream* out = tty) {
    EXCEPTION_MARK;
    ResourceMark rm;
    MethodHandlePrinter printer(root, verbose, out, THREAD);
    if (!HAS_PENDING_EXCEPTION)
      printer.walk(THREAD);
    if (HAS_PENDING_EXCEPTION) {
      oop ex = PENDING_EXCEPTION;
      CLEAR_PENDING_EXCEPTION;
      out->print("\n*** ");
      if (ex != Universe::virtual_machine_error_instance())
        ex->print_on(out);
      else
        out->print("lose: %s", printer.lose_message());
      out->print("\n}\n");
    }
    out->print("\n");
  }
};

extern "C"
void print_method_handle(oop mh) {
  if (java_dyn_MethodHandle::is_instance(mh)) {
    MethodHandlePrinter::print(mh);
  } else {
    tty->print("*** not a method handle: ");
    mh->print();
  }
}

#endif // PRODUCT