view src/share/vm/prims/methodHandles.cpp @ 1716:be3f9c242c9d

6948538: CMS: BOT walkers can fall into object allocation and initialization cracks Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode. Reviewed-by: chrisphi, johnc, poonam
author ysr
date Mon, 16 Aug 2010 15:58:42 -0700
parents 083fde3b838e
children 3e8fbc61cee8
line wrap: on
line source

/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

/*
 * JSR 292 reference implementation: method handles
 */

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

bool MethodHandles::_enabled = false; // set true after successful native linkage

MethodHandleEntry* MethodHandles::_entries[MethodHandles::_EK_LIMIT] = {NULL};
const char*        MethodHandles::_entry_names[_EK_LIMIT+1] = {
  "raise_exception",
  "invokestatic",               // how a MH emulates invokestatic
  "invokespecial",              // ditto for the other invokes...
  "invokevirtual",
  "invokeinterface",
  "bound_ref",                  // these are for BMH...
  "bound_int",
  "bound_long",
  "bound_ref_direct",           // (direct versions have a direct methodOop)
  "bound_int_direct",
  "bound_long_direct",

  // starting at _adapter_mh_first:
  "adapter_retype_only",       // these are for AMH...
  "adapter_retype_raw",
  "adapter_check_cast",
  "adapter_prim_to_prim",
  "adapter_ref_to_prim",
  "adapter_prim_to_ref",
  "adapter_swap_args",
  "adapter_rot_args",
  "adapter_dup_args",
  "adapter_drop_args",
  "adapter_collect_args",
  "adapter_spread_args",
  "adapter_flyby",
  "adapter_ricochet",

  // optimized adapter types:
  "adapter_swap_args/1",
  "adapter_swap_args/2",
  "adapter_rot_args/1,up",
  "adapter_rot_args/1,down",
  "adapter_rot_args/2,up",
  "adapter_rot_args/2,down",
  "adapter_prim_to_prim/i2i",
  "adapter_prim_to_prim/l2i",
  "adapter_prim_to_prim/d2f",
  "adapter_prim_to_prim/i2l",
  "adapter_prim_to_prim/f2d",
  "adapter_ref_to_prim/unboxi",
  "adapter_ref_to_prim/unboxl",
  "adapter_spread_args/0",
  "adapter_spread_args/1",
  "adapter_spread_args/more",

  NULL
};

// Adapters.
MethodHandlesAdapterBlob* MethodHandles::_adapter_code      = NULL;
int                       MethodHandles::_adapter_code_size = StubRoutines::method_handles_adapters_code_size;

jobject MethodHandles::_raise_exception_method;

#ifdef ASSERT
bool MethodHandles::spot_check_entry_names() {
  assert(!strcmp(entry_name(_invokestatic_mh), "invokestatic"), "");
  assert(!strcmp(entry_name(_bound_ref_mh), "bound_ref"), "");
  assert(!strcmp(entry_name(_adapter_retype_only), "adapter_retype_only"), "");
  assert(!strcmp(entry_name(_adapter_ricochet), "adapter_ricochet"), "");
  assert(!strcmp(entry_name(_adapter_opt_unboxi), "adapter_ref_to_prim/unboxi"), "");
  return true;
}
#endif


//------------------------------------------------------------------------------
// MethodHandles::generate_adapters
//
void MethodHandles::generate_adapters() {
  if (!EnableMethodHandles || SystemDictionary::MethodHandle_klass() == NULL)  return;

  assert(_adapter_code == NULL, "generate only once");

  ResourceMark rm;
  TraceTime timer("MethodHandles adapters generation", TraceStartupTime);
  _adapter_code = MethodHandlesAdapterBlob::create(_adapter_code_size);
  if (_adapter_code == NULL)
    vm_exit_out_of_memory(_adapter_code_size, "CodeCache: no room for MethodHandles adapters");
  CodeBuffer code(_adapter_code->instructions_begin(), _adapter_code->instructions_size());

  MethodHandlesAdapterGenerator g(&code);
  g.generate();
}


//------------------------------------------------------------------------------
// MethodHandlesAdapterGenerator::generate
//
void MethodHandlesAdapterGenerator::generate() {
  // Generate generic method handle adapters.
  for (MethodHandles::EntryKind ek = MethodHandles::_EK_FIRST;
       ek < MethodHandles::_EK_LIMIT;
       ek = MethodHandles::EntryKind(1 + (int)ek)) {
    StubCodeMark mark(this, "MethodHandle", MethodHandles::entry_name(ek));
    MethodHandles::generate_method_handle_stub(_masm, ek);
  }
}


void MethodHandles::set_enabled(bool z) {
  if (_enabled != z) {
    guarantee(z && EnableMethodHandles, "can only enable once, and only if -XX:+EnableMethodHandles");
    _enabled = z;
  }
}

// Note: A method which does not have a TRAPS argument cannot block in the GC
// or throw exceptions.  Such methods are used in this file to do something quick
// and local, like parse a data structure.  For speed, such methods work on plain
// oops, not handles.  Trapping methods uniformly operate on handles.

methodOop MethodHandles::decode_vmtarget(oop vmtarget, int vmindex, oop mtype,
                                         klassOop& receiver_limit_result, int& decode_flags_result) {
  if (vmtarget == NULL)  return NULL;
  assert(methodOopDesc::nonvirtual_vtable_index < 0, "encoding");
  if (vmindex < 0) {
    // this DMH performs no dispatch; it is directly bound to a methodOop
    // A MemberName may either be directly bound to a methodOop,
    // or it may use the klass/index form; both forms mean the same thing.
    methodOop m = decode_methodOop(methodOop(vmtarget), decode_flags_result);
    if ((decode_flags_result & _dmf_has_receiver) != 0
        && java_dyn_MethodType::is_instance(mtype)) {
      // Extract receiver type restriction from mtype.ptypes[0].
      objArrayOop ptypes = java_dyn_MethodType::ptypes(mtype);
      oop ptype0 = (ptypes == NULL || ptypes->length() < 1) ? oop(NULL) : ptypes->obj_at(0);
      if (java_lang_Class::is_instance(ptype0))
        receiver_limit_result = java_lang_Class::as_klassOop(ptype0);
    }
    if (vmindex == methodOopDesc::nonvirtual_vtable_index) {
      // this DMH can be an "invokespecial" version
      decode_flags_result &= ~_dmf_does_dispatch;
    } else {
      assert(vmindex == methodOopDesc::invalid_vtable_index, "random vmindex?");
    }
    return m;
  } else {
    assert(vmtarget->is_klass(), "must be class or interface");
    decode_flags_result |= MethodHandles::_dmf_does_dispatch;
    decode_flags_result |= MethodHandles::_dmf_has_receiver;
    receiver_limit_result = (klassOop)vmtarget;
    Klass* tk = Klass::cast((klassOop)vmtarget);
    if (tk->is_interface()) {
      // an itable linkage is <interface, itable index>
      decode_flags_result |= MethodHandles::_dmf_from_interface;
      return klassItable::method_for_itable_index((klassOop)vmtarget, vmindex);
    } else {
      if (!tk->oop_is_instance())
        tk = instanceKlass::cast(SystemDictionary::Object_klass());
      return ((instanceKlass*)tk)->method_at_vtable(vmindex);
    }
  }
}

// MemberName and DirectMethodHandle have the same linkage to the JVM internals.
// (MemberName is the non-operational name used for queries and setup.)

methodOop MethodHandles::decode_DirectMethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result) {
  oop vmtarget = sun_dyn_DirectMethodHandle::vmtarget(mh);
  int vmindex  = sun_dyn_DirectMethodHandle::vmindex(mh);
  oop mtype    = sun_dyn_DirectMethodHandle::type(mh);
  return decode_vmtarget(vmtarget, vmindex, mtype, receiver_limit_result, decode_flags_result);
}

methodOop MethodHandles::decode_BoundMethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result) {
  assert(sun_dyn_BoundMethodHandle::is_instance(mh), "");
  assert(mh->klass() != SystemDictionary::AdapterMethodHandle_klass(), "");
  for (oop bmh = mh;;) {
    // Bound MHs can be stacked to bind several arguments.
    oop target = java_dyn_MethodHandle::vmtarget(bmh);
    if (target == NULL)  return NULL;
    decode_flags_result |= MethodHandles::_dmf_binds_argument;
    klassOop tk = target->klass();
    if (tk == SystemDictionary::BoundMethodHandle_klass()) {
      bmh = target;
      continue;
    } else {
      if (java_dyn_MethodHandle::is_subclass(tk)) {
        //assert(tk == SystemDictionary::DirectMethodHandle_klass(), "end of BMH chain must be DMH");
        return decode_MethodHandle(target, receiver_limit_result, decode_flags_result);
      } else {
        // Optimized case:  binding a receiver to a non-dispatched DMH
        // short-circuits directly to the methodOop.
        // (It might be another argument besides a receiver also.)
        assert(target->is_method(), "must be a simple method");
        decode_flags_result |= MethodHandles::_dmf_binds_method;
        methodOop m = (methodOop) target;
        if (!m->is_static())
          decode_flags_result |= MethodHandles::_dmf_has_receiver;
        return m;
      }
    }
  }
}

methodOop MethodHandles::decode_AdapterMethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result) {
  assert(mh->klass() == SystemDictionary::AdapterMethodHandle_klass(), "");
  for (oop amh = mh;;) {
    // Adapter MHs can be stacked to convert several arguments.
    int conv_op = adapter_conversion_op(sun_dyn_AdapterMethodHandle::conversion(amh));
    decode_flags_result |= (_dmf_adapter_lsb << conv_op) & _DMF_ADAPTER_MASK;
    oop target = java_dyn_MethodHandle::vmtarget(amh);
    if (target == NULL)  return NULL;
    klassOop tk = target->klass();
    if (tk == SystemDictionary::AdapterMethodHandle_klass()) {
      amh = target;
      continue;
    } else {
      // must be a BMH (which will bind some more arguments) or a DMH (for the final call)
      return MethodHandles::decode_MethodHandle(target, receiver_limit_result, decode_flags_result);
    }
  }
}

methodOop MethodHandles::decode_MethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result) {
  if (mh == NULL)  return NULL;
  klassOop mhk = mh->klass();
  assert(java_dyn_MethodHandle::is_subclass(mhk), "must be a MethodHandle");
  if (mhk == SystemDictionary::DirectMethodHandle_klass()) {
    return decode_DirectMethodHandle(mh, receiver_limit_result, decode_flags_result);
  } else if (mhk == SystemDictionary::BoundMethodHandle_klass()) {
    return decode_BoundMethodHandle(mh, receiver_limit_result, decode_flags_result);
  } else if (mhk == SystemDictionary::AdapterMethodHandle_klass()) {
    return decode_AdapterMethodHandle(mh, receiver_limit_result, decode_flags_result);
  } else if (sun_dyn_BoundMethodHandle::is_subclass(mhk)) {
    // could be a JavaMethodHandle (but not an adapter MH)
    return decode_BoundMethodHandle(mh, receiver_limit_result, decode_flags_result);
  } else {
    assert(false, "cannot parse this MH");
    return NULL;              // random MH?
  }
}

methodOop MethodHandles::decode_methodOop(methodOop m, int& decode_flags_result) {
  assert(m->is_method(), "");
  if (m->is_static()) {
    // check that signature begins '(L' or '([' (not '(I', '()', etc.)
    symbolOop sig = m->signature();
    BasicType recv_bt = char2type(sig->byte_at(1));
    // Note: recv_bt might be T_ILLEGAL if byte_at(2) is ')'
    assert(sig->byte_at(0) == '(', "must be method sig");
//     if (recv_bt == T_OBJECT || recv_bt == T_ARRAY)
//       decode_flags_result |= _dmf_has_receiver;
  } else {
    // non-static method
    decode_flags_result |= _dmf_has_receiver;
    if (!m->can_be_statically_bound() && !m->is_initializer()) {
      decode_flags_result |= _dmf_does_dispatch;
      if (Klass::cast(m->method_holder())->is_interface())
        decode_flags_result |= _dmf_from_interface;
    }
  }
  return m;
}


// A trusted party is handing us a cookie to determine a method.
// Let's boil it down to the method oop they really want.
methodOop MethodHandles::decode_method(oop x, klassOop& receiver_limit_result, int& decode_flags_result) {
  decode_flags_result = 0;
  receiver_limit_result = NULL;
  klassOop xk = x->klass();
  if (xk == Universe::methodKlassObj()) {
    return decode_methodOop((methodOop) x, decode_flags_result);
  } else if (xk == SystemDictionary::MemberName_klass()) {
    // Note: This only works if the MemberName has already been resolved.
    return decode_MemberName(x, receiver_limit_result, decode_flags_result);
  } else if (java_dyn_MethodHandle::is_subclass(xk)) {
    return decode_MethodHandle(x, receiver_limit_result, decode_flags_result);
  } else if (xk == SystemDictionary::reflect_Method_klass()) {
    oop clazz  = java_lang_reflect_Method::clazz(x);
    int slot   = java_lang_reflect_Method::slot(x);
    klassOop k = java_lang_Class::as_klassOop(clazz);
    if (k != NULL && Klass::cast(k)->oop_is_instance())
      return decode_methodOop(instanceKlass::cast(k)->method_with_idnum(slot),
                              decode_flags_result);
  } else if (xk == SystemDictionary::reflect_Constructor_klass()) {
    oop clazz  = java_lang_reflect_Constructor::clazz(x);
    int slot   = java_lang_reflect_Constructor::slot(x);
    klassOop k = java_lang_Class::as_klassOop(clazz);
    if (k != NULL && Klass::cast(k)->oop_is_instance())
      return decode_methodOop(instanceKlass::cast(k)->method_with_idnum(slot),
                              decode_flags_result);
  } else {
    // unrecognized object
    assert(!x->is_method(), "already checked");
    assert(!sun_dyn_MemberName::is_instance(x), "already checked");
  }
  return NULL;
}


int MethodHandles::decode_MethodHandle_stack_pushes(oop mh) {
  if (mh->klass() == SystemDictionary::DirectMethodHandle_klass())
    return 0;                   // no push/pop
  int this_vmslots = java_dyn_MethodHandle::vmslots(mh);
  int last_vmslots = 0;
  oop last_mh = mh;
  for (;;) {
    oop target = java_dyn_MethodHandle::vmtarget(last_mh);
    if (target->klass() == SystemDictionary::DirectMethodHandle_klass()) {
      last_vmslots = java_dyn_MethodHandle::vmslots(target);
      break;
    } else if (!java_dyn_MethodHandle::is_instance(target)) {
      // might be klass or method
      assert(target->is_method(), "must get here with a direct ref to method");
      last_vmslots = methodOop(target)->size_of_parameters();
      break;
    }
    last_mh = target;
  }
  // If I am called with fewer VM slots than my ultimate callee,
  // it must be that I push the additionally needed slots.
  // Likewise if am called with more VM slots, I will pop them.
  return (last_vmslots - this_vmslots);
}


// MemberName support

// import sun_dyn_MemberName.*
enum {
  IS_METHOD      = sun_dyn_MemberName::MN_IS_METHOD,
  IS_CONSTRUCTOR = sun_dyn_MemberName::MN_IS_CONSTRUCTOR,
  IS_FIELD       = sun_dyn_MemberName::MN_IS_FIELD,
  IS_TYPE        = sun_dyn_MemberName::MN_IS_TYPE,
  SEARCH_SUPERCLASSES = sun_dyn_MemberName::MN_SEARCH_SUPERCLASSES,
  SEARCH_INTERFACES   = sun_dyn_MemberName::MN_SEARCH_INTERFACES,
  ALL_KINDS      = IS_METHOD | IS_CONSTRUCTOR | IS_FIELD | IS_TYPE,
  VM_INDEX_UNINITIALIZED = sun_dyn_MemberName::VM_INDEX_UNINITIALIZED
};

Handle MethodHandles::new_MemberName(TRAPS) {
  Handle empty;
  instanceKlassHandle k(THREAD, SystemDictionary::MemberName_klass());
  if (!k->is_initialized())  k->initialize(CHECK_(empty));
  return Handle(THREAD, k->allocate_instance(THREAD));
}

void MethodHandles::init_MemberName(oop mname_oop, oop target_oop) {
  if (target_oop->klass() == SystemDictionary::reflect_Field_klass()) {
    oop clazz = java_lang_reflect_Field::clazz(target_oop); // fd.field_holder()
    int slot  = java_lang_reflect_Field::slot(target_oop);  // fd.index()
    int mods  = java_lang_reflect_Field::modifiers(target_oop);
    klassOop k = java_lang_Class::as_klassOop(clazz);
    int offset = instanceKlass::cast(k)->offset_from_fields(slot);
    init_MemberName(mname_oop, k, accessFlags_from(mods), offset);
  } else {
    int decode_flags = 0; klassOop receiver_limit = NULL;
    methodOop m = MethodHandles::decode_method(target_oop,
                                               receiver_limit, decode_flags);
    bool do_dispatch = ((decode_flags & MethodHandles::_dmf_does_dispatch) != 0);
    init_MemberName(mname_oop, m, do_dispatch);
  }
}

void MethodHandles::init_MemberName(oop mname_oop, methodOop m, bool do_dispatch) {
  int flags = ((m->is_initializer() ? IS_CONSTRUCTOR : IS_METHOD)
               | (jushort)( m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS ));
  oop vmtarget = m;
  int vmindex  = methodOopDesc::invalid_vtable_index;  // implies no info yet
  if (!do_dispatch || (flags & IS_CONSTRUCTOR) || m->can_be_statically_bound())
    vmindex = methodOopDesc::nonvirtual_vtable_index; // implies never any dispatch
  assert(vmindex != VM_INDEX_UNINITIALIZED, "Java sentinel value");
  sun_dyn_MemberName::set_vmtarget(mname_oop, vmtarget);
  sun_dyn_MemberName::set_vmindex(mname_oop,  vmindex);
  sun_dyn_MemberName::set_flags(mname_oop,    flags);
  sun_dyn_MemberName::set_clazz(mname_oop,    Klass::cast(m->method_holder())->java_mirror());
}

void MethodHandles::init_MemberName(oop mname_oop, klassOop field_holder, AccessFlags mods, int offset) {
  int flags = (IS_FIELD | (jushort)( mods.as_short() & JVM_RECOGNIZED_FIELD_MODIFIERS ));
  oop vmtarget = field_holder;
  int vmindex  = offset;  // determines the field uniquely when combined with static bit
  assert(vmindex != VM_INDEX_UNINITIALIZED, "bad alias on vmindex");
  sun_dyn_MemberName::set_vmtarget(mname_oop, vmtarget);
  sun_dyn_MemberName::set_vmindex(mname_oop,  vmindex);
  sun_dyn_MemberName::set_flags(mname_oop,    flags);
  sun_dyn_MemberName::set_clazz(mname_oop,    Klass::cast(field_holder)->java_mirror());
}


methodOop MethodHandles::decode_MemberName(oop mname, klassOop& receiver_limit_result, int& decode_flags_result) {
  int flags  = sun_dyn_MemberName::flags(mname);
  if ((flags & (IS_METHOD | IS_CONSTRUCTOR)) == 0)  return NULL;  // not invocable
  oop vmtarget = sun_dyn_MemberName::vmtarget(mname);
  int vmindex  = sun_dyn_MemberName::vmindex(mname);
  if (vmindex == VM_INDEX_UNINITIALIZED)  return NULL; // not resolved
  methodOop m = decode_vmtarget(vmtarget, vmindex, NULL, receiver_limit_result, decode_flags_result);
  oop clazz = sun_dyn_MemberName::clazz(mname);
  if (clazz != NULL && java_lang_Class::is_instance(clazz)) {
    klassOop klass = java_lang_Class::as_klassOop(clazz);
    if (klass != NULL)  receiver_limit_result = klass;
  }
  return m;
}

// An unresolved member name is a mere symbolic reference.
// Resolving it plants a vmtarget/vmindex in it,
// which refers dirctly to JVM internals.
void MethodHandles::resolve_MemberName(Handle mname, TRAPS) {
  assert(sun_dyn_MemberName::is_instance(mname()), "");
#ifdef ASSERT
  // If this assert throws, renegotiate the sentinel value used by the Java code,
  // so that it is distinct from any valid vtable index value, and any special
  // values defined in methodOopDesc::VtableIndexFlag.
  // The point of the slop is to give the Java code and the JVM some room
  // to independently specify sentinel values.
  const int sentinel_slop  = 10;
  const int sentinel_limit = methodOopDesc::highest_unused_vtable_index_value - sentinel_slop;
  assert(VM_INDEX_UNINITIALIZED < sentinel_limit, "Java sentinel != JVM sentinels");
#endif
  if (sun_dyn_MemberName::vmindex(mname()) != VM_INDEX_UNINITIALIZED)
    return;  // already resolved
  oop defc_oop = sun_dyn_MemberName::clazz(mname());
  oop name_str = sun_dyn_MemberName::name(mname());
  oop type_str = sun_dyn_MemberName::type(mname());
  int flags    = sun_dyn_MemberName::flags(mname());

  if (defc_oop == NULL || name_str == NULL || type_str == NULL) {
    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "nothing to resolve");
  }
  klassOop defc_klassOop = java_lang_Class::as_klassOop(defc_oop);
  defc_oop = NULL;  // safety
  if (defc_klassOop == NULL)  return;  // a primitive; no resolution possible
  if (!Klass::cast(defc_klassOop)->oop_is_instance()) {
    if (!Klass::cast(defc_klassOop)->oop_is_array())  return;
    defc_klassOop = SystemDictionary::Object_klass();
  }
  instanceKlassHandle defc(THREAD, defc_klassOop);
  defc_klassOop = NULL;  // safety
  if (defc.is_null()) {
    THROW_MSG(vmSymbols::java_lang_InternalError(), "primitive class");
  }
  defc->link_class(CHECK);

  // convert the external string name to an internal symbol
  symbolHandle name(THREAD, java_lang_String::as_symbol_or_null(name_str));
  if (name.is_null())  return;  // no such name
  name_str = NULL;  // safety

  Handle polymorphic_method_type;
  bool polymorphic_signature = false;
  if ((flags & ALL_KINDS) == IS_METHOD &&
      (defc() == SystemDictionary::InvokeDynamic_klass() ||
       (defc() == SystemDictionary::MethodHandle_klass() &&
        methodOopDesc::is_method_handle_invoke_name(name()))))
    polymorphic_signature = true;

  // convert the external string or reflective type to an internal signature
  symbolHandle type; {
    symbolOop type_sym = NULL;
    if (java_dyn_MethodType::is_instance(type_str)) {
      type_sym = java_dyn_MethodType::as_signature(type_str, polymorphic_signature, CHECK);
      if (polymorphic_signature)
        polymorphic_method_type = Handle(THREAD, type_str);  //preserve exactly
    } else if (java_lang_Class::is_instance(type_str)) {
      type_sym = java_lang_Class::as_signature(type_str, false, CHECK);
    } else if (java_lang_String::is_instance(type_str)) {
      if (polymorphic_signature) {
        type     = java_lang_String::as_symbol(type_str, CHECK);
      } else {
        type_sym = java_lang_String::as_symbol_or_null(type_str);
      }
    } else {
      THROW_MSG(vmSymbols::java_lang_InternalError(), "unrecognized type");
    }
    if (type_sym != NULL)
      type = symbolHandle(THREAD, type_sym);
  }
  if (type.is_null())  return;  // no such signature exists in the VM
  type_str = NULL; // safety

  // Time to do the lookup.
  switch (flags & ALL_KINDS) {
  case IS_METHOD:
    {
      CallInfo result;
      {
        EXCEPTION_MARK;
        if ((flags & JVM_ACC_STATIC) != 0) {
          LinkResolver::resolve_static_call(result,
                        defc, name, type, KlassHandle(), false, false, THREAD);
        } else if (defc->is_interface()) {
          LinkResolver::resolve_interface_call(result, Handle(), defc,
                        defc, name, type, KlassHandle(), false, false, THREAD);
        } else {
          LinkResolver::resolve_virtual_call(result, Handle(), defc,
                        defc, name, type, KlassHandle(), false, false, THREAD);
        }
        if (HAS_PENDING_EXCEPTION) {
          CLEAR_PENDING_EXCEPTION;
          break;  // go to second chance
        }
      }
      methodHandle m = result.resolved_method();
      oop vmtarget = NULL;
      int vmindex = methodOopDesc::nonvirtual_vtable_index;
      if (defc->is_interface()) {
        vmindex = klassItable::compute_itable_index(m());
        assert(vmindex >= 0, "");
      } else if (result.has_vtable_index()) {
        vmindex = result.vtable_index();
        assert(vmindex >= 0, "");
      }
      assert(vmindex != VM_INDEX_UNINITIALIZED, "");
      if (vmindex < 0) {
        assert(result.is_statically_bound(), "");
        vmtarget = m();
      } else {
        vmtarget = result.resolved_klass()->as_klassOop();
      }
      int mods = (m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS);
      sun_dyn_MemberName::set_vmtarget(mname(), vmtarget);
      sun_dyn_MemberName::set_vmindex(mname(),  vmindex);
      sun_dyn_MemberName::set_modifiers(mname(), mods);
      DEBUG_ONLY(int junk; klassOop junk2);
      assert(decode_MemberName(mname(), junk2, junk) == result.resolved_method()(),
             "properly stored for later decoding");
      return;
    }
  case IS_CONSTRUCTOR:
    {
      CallInfo result;
      {
        EXCEPTION_MARK;
        if (name() == vmSymbols::object_initializer_name()) {
          LinkResolver::resolve_special_call(result,
                        defc, name, type, KlassHandle(), false, THREAD);
        } else {
          break;                // will throw after end of switch
        }
        if (HAS_PENDING_EXCEPTION) {
          CLEAR_PENDING_EXCEPTION;
          return;
        }
      }
      assert(result.is_statically_bound(), "");
      methodHandle m = result.resolved_method();
      oop vmtarget = m();
      int vmindex  = methodOopDesc::nonvirtual_vtable_index;
      int mods     = (m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS);
      sun_dyn_MemberName::set_vmtarget(mname(), vmtarget);
      sun_dyn_MemberName::set_vmindex(mname(),  vmindex);
      sun_dyn_MemberName::set_modifiers(mname(), mods);
      DEBUG_ONLY(int junk; klassOop junk2);
      assert(decode_MemberName(mname(), junk2, junk) == result.resolved_method()(),
             "properly stored for later decoding");
      return;
    }
  case IS_FIELD:
    {
      // This is taken from LinkResolver::resolve_field, sans access checks.
      fieldDescriptor fd; // find_field initializes fd if found
      KlassHandle sel_klass(THREAD, instanceKlass::cast(defc())->find_field(name(), type(), &fd));
      // check if field exists; i.e., if a klass containing the field def has been selected
      if (sel_klass.is_null())  return;
      oop vmtarget = sel_klass->as_klassOop();
      int vmindex  = fd.offset();
      int mods     = (fd.access_flags().as_short() & JVM_RECOGNIZED_FIELD_MODIFIERS);
      if (vmindex == VM_INDEX_UNINITIALIZED)  break;  // should not happen
      sun_dyn_MemberName::set_vmtarget(mname(),  vmtarget);
      sun_dyn_MemberName::set_vmindex(mname(),   vmindex);
      sun_dyn_MemberName::set_modifiers(mname(), mods);
      return;
    }
  default:
    THROW_MSG(vmSymbols::java_lang_InternalError(), "unrecognized MemberName format");
  }

  // Second chance.
  if (polymorphic_method_type.not_null()) {
    // Look on a non-null class loader.
    Handle cur_class_loader;
    const int nptypes = java_dyn_MethodType::ptype_count(polymorphic_method_type());
    for (int i = 0; i <= nptypes; i++) {
      oop type_mirror;
      if (i < nptypes)  type_mirror = java_dyn_MethodType::ptype(polymorphic_method_type(), i);
      else              type_mirror = java_dyn_MethodType::rtype(polymorphic_method_type());
      klassOop example_type = java_lang_Class::as_klassOop(type_mirror);
      if (example_type == NULL)  continue;
      oop class_loader = Klass::cast(example_type)->class_loader();
      if (class_loader == NULL || class_loader == cur_class_loader())  continue;
      cur_class_loader = Handle(THREAD, class_loader);
      methodOop m = SystemDictionary::find_method_handle_invoke(name,
                                                                type,
                                                                KlassHandle(THREAD, example_type),
                                                                THREAD);
      if (HAS_PENDING_EXCEPTION) {
        CLEAR_PENDING_EXCEPTION;
        m = NULL;
        // try again with a different class loader...
      }
      if (m != NULL) {
        int mods = (m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS);
        sun_dyn_MemberName::set_vmtarget(mname(),  m);
        sun_dyn_MemberName::set_vmindex(mname(),   m->vtable_index());
        sun_dyn_MemberName::set_modifiers(mname(), mods);
        return;
      }
    }
  }
}

// Conversely, a member name which is only initialized from JVM internals
// may have null defc, name, and type fields.
// Resolving it plants a vmtarget/vmindex in it,
// which refers directly to JVM internals.
void MethodHandles::expand_MemberName(Handle mname, int suppress, TRAPS) {
  assert(sun_dyn_MemberName::is_instance(mname()), "");
  oop vmtarget = sun_dyn_MemberName::vmtarget(mname());
  int vmindex  = sun_dyn_MemberName::vmindex(mname());
  if (vmtarget == NULL || vmindex == VM_INDEX_UNINITIALIZED) {
    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "nothing to expand");
  }

  bool have_defc = (sun_dyn_MemberName::clazz(mname()) != NULL);
  bool have_name = (sun_dyn_MemberName::name(mname()) != NULL);
  bool have_type = (sun_dyn_MemberName::type(mname()) != NULL);
  int flags      = sun_dyn_MemberName::flags(mname());

  if (suppress != 0) {
    if (suppress & _suppress_defc)  have_defc = true;
    if (suppress & _suppress_name)  have_name = true;
    if (suppress & _suppress_type)  have_type = true;
  }

  if (have_defc && have_name && have_type)  return;  // nothing needed

  switch (flags & ALL_KINDS) {
  case IS_METHOD:
  case IS_CONSTRUCTOR:
    {
      klassOop receiver_limit = NULL;
      int      decode_flags   = 0;
      methodHandle m(THREAD, decode_vmtarget(vmtarget, vmindex, NULL,
                                             receiver_limit, decode_flags));
      if (m.is_null())  break;
      if (!have_defc) {
        klassOop defc = m->method_holder();
        if (receiver_limit != NULL && receiver_limit != defc
            && Klass::cast(receiver_limit)->is_subtype_of(defc))
          defc = receiver_limit;
        sun_dyn_MemberName::set_clazz(mname(), Klass::cast(defc)->java_mirror());
      }
      if (!have_name) {
        //not java_lang_String::create_from_symbol; let's intern member names
        Handle name = StringTable::intern(m->name(), CHECK);
        sun_dyn_MemberName::set_name(mname(), name());
      }
      if (!have_type) {
        Handle type = java_lang_String::create_from_symbol(m->signature(), CHECK);
        sun_dyn_MemberName::set_type(mname(), type());
      }
      return;
    }
  case IS_FIELD:
    {
      // This is taken from LinkResolver::resolve_field, sans access checks.
      if (!vmtarget->is_klass())  break;
      if (!Klass::cast((klassOop) vmtarget)->oop_is_instance())  break;
      instanceKlassHandle defc(THREAD, (klassOop) vmtarget);
      bool is_static = ((flags & JVM_ACC_STATIC) != 0);
      fieldDescriptor fd; // find_field initializes fd if found
      if (!defc->find_field_from_offset(vmindex, is_static, &fd))
        break;                  // cannot expand
      if (!have_defc) {
        sun_dyn_MemberName::set_clazz(mname(), defc->java_mirror());
      }
      if (!have_name) {
        //not java_lang_String::create_from_symbol; let's intern member names
        Handle name = StringTable::intern(fd.name(), CHECK);
        sun_dyn_MemberName::set_name(mname(), name());
      }
      if (!have_type) {
        Handle type = java_lang_String::create_from_symbol(fd.signature(), CHECK);
        sun_dyn_MemberName::set_type(mname(), type());
      }
      return;
    }
  }
  THROW_MSG(vmSymbols::java_lang_InternalError(), "unrecognized MemberName format");
}

int MethodHandles::find_MemberNames(klassOop k,
                                    symbolOop name, symbolOop sig,
                                    int mflags, klassOop caller,
                                    int skip, objArrayOop results) {
  DEBUG_ONLY(No_Safepoint_Verifier nsv);
  // this code contains no safepoints!

  // %%% take caller into account!

  if (k == NULL || !Klass::cast(k)->oop_is_instance())  return -1;

  int rfill = 0, rlimit = results->length(), rskip = skip;
  // overflow measurement:
  int overflow = 0, overflow_limit = MAX2(1000, rlimit);

  int match_flags = mflags;
  bool search_superc = ((match_flags & SEARCH_SUPERCLASSES) != 0);
  bool search_intfc  = ((match_flags & SEARCH_INTERFACES)   != 0);
  bool local_only = !(search_superc | search_intfc);
  bool classes_only = false;

  if (name != NULL) {
    if (name->utf8_length() == 0)  return 0; // a match is not possible
  }
  if (sig != NULL) {
    if (sig->utf8_length() == 0)  return 0; // a match is not possible
    if (sig->byte_at(0) == '(')
      match_flags &= ~(IS_FIELD | IS_TYPE);
    else
      match_flags &= ~(IS_CONSTRUCTOR | IS_METHOD);
  }

  if ((match_flags & IS_TYPE) != 0) {
    // NYI, and Core Reflection works quite well for this query
  }

  if ((match_flags & IS_FIELD) != 0) {
    for (FieldStream st(k, local_only, !search_intfc); !st.eos(); st.next()) {
      if (name != NULL && st.name() != name)
          continue;
      if (sig != NULL && st.signature() != sig)
        continue;
      // passed the filters
      if (rskip > 0) {
        --rskip;
      } else if (rfill < rlimit) {
        oop result = results->obj_at(rfill++);
        if (!sun_dyn_MemberName::is_instance(result))
          return -99;  // caller bug!
        MethodHandles::init_MemberName(result, st.klass()->as_klassOop(), st.access_flags(), st.offset());
      } else if (++overflow >= overflow_limit) {
        match_flags = 0; break; // got tired of looking at overflow
      }
    }
  }

  if ((match_flags & (IS_METHOD | IS_CONSTRUCTOR)) != 0) {
    // watch out for these guys:
    symbolOop init_name   = vmSymbols::object_initializer_name();
    symbolOop clinit_name = vmSymbols::class_initializer_name();
    if (name == clinit_name)  clinit_name = NULL; // hack for exposing <clinit>
    bool negate_name_test = false;
    // fix name so that it captures the intention of IS_CONSTRUCTOR
    if (!(match_flags & IS_METHOD)) {
      // constructors only
      if (name == NULL) {
        name = init_name;
      } else if (name != init_name) {
        return 0;               // no constructors of this method name
      }
    } else if (!(match_flags & IS_CONSTRUCTOR)) {
      // methods only
      if (name == NULL) {
        name = init_name;
        negate_name_test = true; // if we see the name, we *omit* the entry
      } else if (name == init_name) {
        return 0;               // no methods of this constructor name
      }
    } else {
      // caller will accept either sort; no need to adjust name
    }
    for (MethodStream st(k, local_only, !search_intfc); !st.eos(); st.next()) {
      methodOop m = st.method();
      symbolOop m_name = m->name();
      if (m_name == clinit_name)
        continue;
      if (name != NULL && ((m_name != name) ^ negate_name_test))
          continue;
      if (sig != NULL && m->signature() != sig)
        continue;
      // passed the filters
      if (rskip > 0) {
        --rskip;
      } else if (rfill < rlimit) {
        oop result = results->obj_at(rfill++);
        if (!sun_dyn_MemberName::is_instance(result))
          return -99;  // caller bug!
        MethodHandles::init_MemberName(result, m, true);
      } else if (++overflow >= overflow_limit) {
        match_flags = 0; break; // got tired of looking at overflow
      }
    }
  }

  // return number of elements we at leasted wanted to initialize
  return rfill + overflow;
}


// Decode this java.lang.Class object into an instanceKlass, if possible.
// Throw IAE if not
instanceKlassHandle MethodHandles::resolve_instance_klass(oop java_mirror_oop, TRAPS) {
  instanceKlassHandle empty;
  klassOop caller = NULL;
  if (java_lang_Class::is_instance(java_mirror_oop)) {
    caller = java_lang_Class::as_klassOop(java_mirror_oop);
  }
  if (caller == NULL || !Klass::cast(caller)->oop_is_instance()) {
    THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), "not a class", empty);
  }
  return instanceKlassHandle(THREAD, caller);
}



// Decode the vmtarget field of a method handle.
// Sanitize out methodOops, klassOops, and any other non-Java data.
// This is for debugging and reflection.
oop MethodHandles::encode_target(Handle mh, int format, TRAPS) {
  assert(java_dyn_MethodHandle::is_instance(mh()), "must be a MH");
  if (format == ETF_HANDLE_OR_METHOD_NAME) {
    oop target = java_dyn_MethodHandle::vmtarget(mh());
    if (target == NULL) {
      return NULL;                // unformed MH
    }
    klassOop tklass = target->klass();
    if (Klass::cast(tklass)->is_subclass_of(SystemDictionary::Object_klass())) {
      return target;              // target is another MH (or something else?)
    }
  }
  if (format == ETF_DIRECT_HANDLE) {
    oop target = mh();
    for (;;) {
      if (target->klass() == SystemDictionary::DirectMethodHandle_klass()) {
        return target;
      }
      if (!java_dyn_MethodHandle::is_instance(target)){
        return NULL;                // unformed MH
      }
      target = java_dyn_MethodHandle::vmtarget(target);
    }
  }
  // cases of metadata in MH.vmtarget:
  // - AMH can have methodOop for static invoke with bound receiver
  // - DMH can have methodOop for static invoke (on variable receiver)
  // - DMH can have klassOop for dispatched (non-static) invoke
  klassOop receiver_limit = NULL;
  int decode_flags = 0;
  methodOop m = decode_MethodHandle(mh(), receiver_limit, decode_flags);
  if (m == NULL)  return NULL;
  switch (format) {
  case ETF_REFLECT_METHOD:
    // same as jni_ToReflectedMethod:
    if (m->is_initializer()) {
      return Reflection::new_constructor(m, THREAD);
    } else {
      return Reflection::new_method(m, UseNewReflection, false, THREAD);
    }

  case ETF_HANDLE_OR_METHOD_NAME:   // method, not handle
  case ETF_METHOD_NAME:
    {
      if (SystemDictionary::MemberName_klass() == NULL)  break;
      instanceKlassHandle mname_klass(THREAD, SystemDictionary::MemberName_klass());
      mname_klass->initialize(CHECK_NULL);
      Handle mname = mname_klass->allocate_instance_handle(CHECK_NULL);
      sun_dyn_MemberName::set_vmindex(mname(), VM_INDEX_UNINITIALIZED);
      bool do_dispatch = ((decode_flags & MethodHandles::_dmf_does_dispatch) != 0);
      init_MemberName(mname(), m, do_dispatch);
      expand_MemberName(mname, 0, CHECK_NULL);
      return mname();
    }
  }

  // Unknown format code.
  char msg[50];
  jio_snprintf(msg, sizeof(msg), "unknown getTarget format=%d", format);
  THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), msg);
}

static const char* always_null_names[] = {
  "java/lang/Void",
  "java/lang/Null",
  //"java/lang/Nothing",
  "sun/dyn/empty/Empty",
  NULL
};

static bool is_always_null_type(klassOop klass) {
  if (!Klass::cast(klass)->oop_is_instance())  return false;
  instanceKlass* ik = instanceKlass::cast(klass);
  // Must be on the boot class path:
  if (ik->class_loader() != NULL)  return false;
  // Check the name.
  symbolOop name = ik->name();
  for (int i = 0; ; i++) {
    const char* test_name = always_null_names[i];
    if (test_name == NULL)  break;
    if (name->equals(test_name))
      return true;
  }
  return false;
}

bool MethodHandles::class_cast_needed(klassOop src, klassOop dst) {
  if (src == dst || dst == SystemDictionary::Object_klass())
    return false;                               // quickest checks
  Klass* srck = Klass::cast(src);
  Klass* dstk = Klass::cast(dst);
  if (dstk->is_interface()) {
    // interface receivers can safely be viewed as untyped,
    // because interface calls always include a dynamic check
    //dstk = Klass::cast(SystemDictionary::Object_klass());
    return false;
  }
  if (srck->is_interface()) {
    // interface arguments must be viewed as untyped
    //srck = Klass::cast(SystemDictionary::Object_klass());
    return true;
  }
  if (is_always_null_type(src)) {
    // some source types are known to be never instantiated;
    // they represent references which are always null
    // such null references never fail to convert safely
    return false;
  }
  return !srck->is_subclass_of(dstk->as_klassOop());
}

static oop object_java_mirror() {
  return Klass::cast(SystemDictionary::Object_klass())->java_mirror();
}

bool MethodHandles::same_basic_type_for_arguments(BasicType src,
                                                  BasicType dst,
                                                  bool raw,
                                                  bool for_return) {
  if (for_return) {
    // return values can always be forgotten:
    if (dst == T_VOID)  return true;
    if (src == T_VOID)  return raw && (dst == T_INT);
    // We allow caller to receive a garbage int, which is harmless.
    // This trick is pulled by trusted code (see VerifyType.canPassRaw).
  }
  assert(src != T_VOID && dst != T_VOID, "should not be here");
  if (src == dst)  return true;
  if (type2size[src] != type2size[dst])  return false;
  // allow reinterpretation casts for integral widening
  if (is_subword_type(src)) { // subwords can fit in int or other subwords
    if (dst == T_INT)         // any subword fits in an int
      return true;
    if (src == T_BOOLEAN)     // boolean fits in any subword
      return is_subword_type(dst);
    if (src == T_BYTE && dst == T_SHORT)
      return true;            // remaining case: byte fits in short
  }
  // allow float/fixed reinterpretation casts
  if (src == T_FLOAT)   return dst == T_INT;
  if (src == T_INT)     return dst == T_FLOAT;
  if (src == T_DOUBLE)  return dst == T_LONG;
  if (src == T_LONG)    return dst == T_DOUBLE;
  return false;
}

const char* MethodHandles::check_method_receiver(methodOop m,
                                                 klassOop passed_recv_type) {
  assert(!m->is_static(), "caller resp.");
  if (passed_recv_type == NULL)
    return "receiver type is primitive";
  if (class_cast_needed(passed_recv_type, m->method_holder())) {
    Klass* formal = Klass::cast(m->method_holder());
    return SharedRuntime::generate_class_cast_message("receiver type",
                                                      formal->external_name());
  }
  return NULL;                  // checks passed
}

// Verify that m's signature can be called type-safely by a method handle
// of the given method type 'mtype'.
// It takes a TRAPS argument because it must perform symbol lookups.
void MethodHandles::verify_method_signature(methodHandle m,
                                            Handle mtype,
                                            int first_ptype_pos,
                                            KlassHandle insert_ptype,
                                            TRAPS) {
  objArrayHandle ptypes(THREAD, java_dyn_MethodType::ptypes(mtype()));
  int pnum = first_ptype_pos;
  int pmax = ptypes->length();
  int mnum = 0;                 // method argument
  const char* err = NULL;
  for (SignatureStream ss(m->signature()); !ss.is_done(); ss.next()) {
    oop ptype_oop = NULL;
    if (ss.at_return_type()) {
      if (pnum != pmax)
        { err = "too many arguments"; break; }
      ptype_oop = java_dyn_MethodType::rtype(mtype());
    } else {
      if (pnum >= pmax)
        { err = "not enough arguments"; break; }
      if (pnum >= 0)
        ptype_oop = ptypes->obj_at(pnum);
      else if (insert_ptype.is_null())
        ptype_oop = NULL;
      else
        ptype_oop = insert_ptype->java_mirror();
      pnum += 1;
      mnum += 1;
    }
    klassOop  pklass = NULL;
    BasicType ptype  = T_OBJECT;
    if (ptype_oop != NULL)
      ptype = java_lang_Class::as_BasicType(ptype_oop, &pklass);
    else
      // null does not match any non-reference; use Object to report the error
      pklass = SystemDictionary::Object_klass();
    klassOop  mklass = NULL;
    BasicType mtype  = ss.type();
    if (mtype == T_ARRAY)  mtype = T_OBJECT; // fold all refs to T_OBJECT
    if (mtype == T_OBJECT) {
      if (ptype_oop == NULL) {
        // null matches any reference
        continue;
      }
      KlassHandle pklass_handle(THREAD, pklass); pklass = NULL;
      // If we fail to resolve types at this point, we will throw an error.
      symbolOop    name_oop = ss.as_symbol(CHECK);
      symbolHandle name(THREAD, name_oop);
      instanceKlass* mk = instanceKlass::cast(m->method_holder());
      Handle loader(THREAD, mk->class_loader());
      Handle domain(THREAD, mk->protection_domain());
      mklass = SystemDictionary::resolve_or_null(name, loader, domain, CHECK);
      pklass = pklass_handle();
      if (mklass == NULL && pklass != NULL &&
          Klass::cast(pklass)->name() == name() &&
          m->is_method_handle_invoke()) {
        // Assume a match.  We can't really decode the signature of MH.invoke*.
        continue;
      }
    }
    if (!ss.at_return_type()) {
      err = check_argument_type_change(ptype, pklass, mtype, mklass, mnum);
    } else {
      err = check_return_type_change(mtype, mklass, ptype, pklass); // note reversal!
    }
    if (err != NULL)  break;
  }

  if (err != NULL) {
    THROW_MSG(vmSymbols::java_lang_InternalError(), err);
  }
}

// Main routine for verifying the MethodHandle.type of a proposed
// direct or bound-direct method handle.
void MethodHandles::verify_method_type(methodHandle m,
                                       Handle mtype,
                                       bool has_bound_recv,
                                       KlassHandle bound_recv_type,
                                       TRAPS) {
  bool m_needs_receiver = !m->is_static();

  const char* err = NULL;

  int first_ptype_pos = m_needs_receiver ? 1 : 0;
  if (has_bound_recv) {
    first_ptype_pos -= 1;  // ptypes do not include the bound argument; start earlier in them
    if (m_needs_receiver && bound_recv_type.is_null())
      { err = "bound receiver is not an object"; goto die; }
  }

  if (m_needs_receiver && err == NULL) {
    objArrayOop ptypes = java_dyn_MethodType::ptypes(mtype());
    if (ptypes->length() < first_ptype_pos)
      { err = "receiver argument is missing"; goto die; }
    if (has_bound_recv)
      err = check_method_receiver(m(), bound_recv_type->as_klassOop());
    else
      err = check_method_receiver(m(), java_lang_Class::as_klassOop(ptypes->obj_at(first_ptype_pos-1)));
    if (err != NULL)  goto die;
  }

  // Check the other arguments for mistypes.
  verify_method_signature(m, mtype, first_ptype_pos, bound_recv_type, CHECK);
  return;

 die:
  THROW_MSG(vmSymbols::java_lang_InternalError(), err);
}

void MethodHandles::verify_vmslots(Handle mh, TRAPS) {
  // Verify vmslots.
  int check_slots = argument_slot_count(java_dyn_MethodHandle::type(mh()));
  if (java_dyn_MethodHandle::vmslots(mh()) != check_slots) {
    THROW_MSG(vmSymbols::java_lang_InternalError(), "bad vmslots in BMH");
  }
}

void MethodHandles::verify_vmargslot(Handle mh, int argnum, int argslot, TRAPS) {
  // Verify that argslot points at the given argnum.
  int check_slot = argument_slot(java_dyn_MethodHandle::type(mh()), argnum);
  if (argslot != check_slot || argslot < 0) {
    const char* fmt = "for argnum of %d, vmargslot is %d, should be %d";
    size_t msglen = strlen(fmt) + 3*11 + 1;
    char* msg = NEW_RESOURCE_ARRAY(char, msglen);
    jio_snprintf(msg, msglen, fmt, argnum, argslot, check_slot);
    THROW_MSG(vmSymbols::java_lang_InternalError(), msg);
  }
}

// Verify the correspondence between two method types.
// Apart from the advertised changes, caller method type X must
// be able to invoke the callee method Y type with no violations
// of type integrity.
// Return NULL if all is well, else a short error message.
const char* MethodHandles::check_method_type_change(oop src_mtype, int src_beg, int src_end,
                                                    int insert_argnum, oop insert_type,
                                                    int change_argnum, oop change_type,
                                                    int delete_argnum,
                                                    oop dst_mtype, int dst_beg, int dst_end,
                                                    bool raw) {
  objArrayOop src_ptypes = java_dyn_MethodType::ptypes(src_mtype);
  objArrayOop dst_ptypes = java_dyn_MethodType::ptypes(dst_mtype);

  int src_max = src_ptypes->length();
  int dst_max = dst_ptypes->length();

  if (src_end == -1)  src_end = src_max;
  if (dst_end == -1)  dst_end = dst_max;

  assert(0 <= src_beg && src_beg <= src_end && src_end <= src_max, "oob");
  assert(0 <= dst_beg && dst_beg <= dst_end && dst_end <= dst_max, "oob");

  // pending actions; set to -1 when done:
  int ins_idx = insert_argnum, chg_idx = change_argnum, del_idx = delete_argnum;

  const char* err = NULL;

  // Walk along each array of parameter types, including a virtual
  // NULL end marker at the end of each.
  for (int src_idx = src_beg, dst_idx = dst_beg;
       (src_idx <= src_end && dst_idx <= dst_end);
       src_idx++, dst_idx++) {
    oop src_type = (src_idx == src_end) ? oop(NULL) : src_ptypes->obj_at(src_idx);
    oop dst_type = (dst_idx == dst_end) ? oop(NULL) : dst_ptypes->obj_at(dst_idx);
    bool fix_null_src_type = false;

    // Perform requested edits.
    if (ins_idx == src_idx) {
      // note that the inserted guy is never affected by a change or deletion
      ins_idx = -1;
      src_type = insert_type;
      fix_null_src_type = true;
      --src_idx;                // back up to process src type on next loop
      src_idx = src_end;
    } else {
      // note that the changed guy can be immediately deleted
      if (chg_idx == src_idx) {
        chg_idx = -1;
        assert(src_idx < src_end, "oob");
        src_type = change_type;
        fix_null_src_type = true;
      }
      if (del_idx == src_idx) {
        del_idx = -1;
        assert(src_idx < src_end, "oob");
        --dst_idx;
        continue;               // rerun loop after skipping this position
      }
    }

    if (src_type == NULL && fix_null_src_type)
      // explicit null in this case matches any dest reference
      src_type = (java_lang_Class::is_primitive(dst_type) ? object_java_mirror() : dst_type);

    // Compare the two argument types.
    if (src_type != dst_type) {
      if (src_type == NULL)  return "not enough arguments";
      if (dst_type == NULL)  return "too many arguments";
      err = check_argument_type_change(src_type, dst_type, dst_idx, raw);
      if (err != NULL)  return err;
    }
  }

  // Now compare return types also.
  oop src_rtype = java_dyn_MethodType::rtype(src_mtype);
  oop dst_rtype = java_dyn_MethodType::rtype(dst_mtype);
  if (src_rtype != dst_rtype) {
    err = check_return_type_change(dst_rtype, src_rtype, raw); // note reversal!
    if (err != NULL)  return err;
  }

  assert(err == NULL, "");
  return NULL;  // all is well
}


const char* MethodHandles::check_argument_type_change(BasicType src_type,
                                                      klassOop src_klass,
                                                      BasicType dst_type,
                                                      klassOop dst_klass,
                                                      int argnum,
                                                      bool raw) {
  const char* err = NULL;
  bool for_return = (argnum < 0);

  // just in case:
  if (src_type == T_ARRAY)  src_type = T_OBJECT;
  if (dst_type == T_ARRAY)  dst_type = T_OBJECT;

  // Produce some nice messages if VerifyMethodHandles is turned on:
  if (!same_basic_type_for_arguments(src_type, dst_type, raw, for_return)) {
    if (src_type == T_OBJECT) {
      if (raw && dst_type == T_INT && is_always_null_type(src_klass))
        return NULL;    // OK to convert a null pointer to a garbage int
      err = ((argnum >= 0)
             ? "type mismatch: passing a %s for method argument #%d, which expects primitive %s"
             : "type mismatch: returning a %s, but caller expects primitive %s");
    } else if (dst_type == T_OBJECT) {
      err = ((argnum >= 0)
             ? "type mismatch: passing a primitive %s for method argument #%d, which expects %s"
             : "type mismatch: returning a primitive %s, but caller expects %s");
    } else {
      err = ((argnum >= 0)
             ? "type mismatch: passing a %s for method argument #%d, which expects %s"
             : "type mismatch: returning a %s, but caller expects %s");
    }
  } else if (src_type == T_OBJECT && dst_type == T_OBJECT &&
             class_cast_needed(src_klass, dst_klass)) {
    if (!class_cast_needed(dst_klass, src_klass)) {
      if (raw)
        return NULL;    // reverse cast is OK; the MH target is trusted to enforce it
      err = ((argnum >= 0)
             ? "cast required: passing a %s for method argument #%d, which expects %s"
             : "cast required: returning a %s, but caller expects %s");
    } else {
      err = ((argnum >= 0)
             ? "reference mismatch: passing a %s for method argument #%d, which expects %s"
             : "reference mismatch: returning a %s, but caller expects %s");
    }
  } else {
    // passed the obstacle course
    return NULL;
  }

  // format, format, format
  const char* src_name = type2name(src_type);
  const char* dst_name = type2name(dst_type);
  if (src_type == T_OBJECT)  src_name = Klass::cast(src_klass)->external_name();
  if (dst_type == T_OBJECT)  dst_name = Klass::cast(dst_klass)->external_name();
  if (src_name == NULL)  src_name = "unknown type";
  if (dst_name == NULL)  dst_name = "unknown type";

  size_t msglen = strlen(err) + strlen(src_name) + strlen(dst_name) + (argnum < 10 ? 1 : 11);
  char* msg = NEW_RESOURCE_ARRAY(char, msglen + 1);
  if (argnum >= 0) {
    assert(strstr(err, "%d") != NULL, "");
    jio_snprintf(msg, msglen, err, src_name, argnum, dst_name);
  } else {
    assert(strstr(err, "%d") == NULL, "");
    jio_snprintf(msg, msglen, err, src_name,         dst_name);
  }
  return msg;
}

// Compute the depth within the stack of the given argument, i.e.,
// the combined size of arguments to the right of the given argument.
// For the last argument (ptypes.length-1) this will be zero.
// For the first argument (0) this will be the size of all
// arguments but that one.  For the special number -1, this
// will be the size of all arguments, including the first.
// If the argument is neither -1 nor a valid argument index,
// then return a negative number.  Otherwise, the result
// is in the range [0..vmslots] inclusive.
int MethodHandles::argument_slot(oop method_type, int arg) {
  objArrayOop ptypes = java_dyn_MethodType::ptypes(method_type);
  int argslot = 0;
  int len = ptypes->length();
  if (arg < -1 || arg >= len)  return -99;
  for (int i = len-1; i > arg; i--) {
    BasicType bt = java_lang_Class::as_BasicType(ptypes->obj_at(i));
    argslot += type2size[bt];
  }
  assert(argument_slot_to_argnum(method_type, argslot) == arg, "inverse works");
  return argslot;
}

// Given a slot number, return the argument number.
int MethodHandles::argument_slot_to_argnum(oop method_type, int query_argslot) {
  objArrayOop ptypes = java_dyn_MethodType::ptypes(method_type);
  int argslot = 0;
  int len = ptypes->length();
  for (int i = len-1; i >= 0; i--) {
    if (query_argslot == argslot)  return i;
    BasicType bt = java_lang_Class::as_BasicType(ptypes->obj_at(i));
    argslot += type2size[bt];
  }
  // return pseudo-arg deepest in stack:
  if (query_argslot == argslot)  return -1;
  return -99;                   // oob slot, or splitting a double-slot arg
}

methodHandle MethodHandles::dispatch_decoded_method(methodHandle m,
                                                    KlassHandle receiver_limit,
                                                    int decode_flags,
                                                    KlassHandle receiver_klass,
                                                    TRAPS) {
  assert((decode_flags & ~_DMF_DIRECT_MASK) == 0, "must be direct method reference");
  assert((decode_flags & _dmf_has_receiver) != 0, "must have a receiver or first reference argument");

  if (!m->is_static() &&
      (receiver_klass.is_null() || !receiver_klass->is_subtype_of(m->method_holder())))
    // given type does not match class of method, or receiver is null!
    // caller should have checked this, but let's be extra careful...
    return methodHandle();

  if (receiver_limit.not_null() &&
      (receiver_klass.not_null() && !receiver_klass->is_subtype_of(receiver_limit())))
    // given type is not limited to the receiver type
    // note that a null receiver can match any reference value, for a static method
    return methodHandle();

  if (!(decode_flags & MethodHandles::_dmf_does_dispatch)) {
    // pre-dispatched or static method (null receiver is OK for static)
    return m;

  } else if (receiver_klass.is_null()) {
    // null receiver value; cannot dispatch
    return methodHandle();

  } else if (!(decode_flags & MethodHandles::_dmf_from_interface)) {
    // perform virtual dispatch
    int vtable_index = m->vtable_index();
    guarantee(vtable_index >= 0, "valid vtable index");

    // receiver_klass might be an arrayKlassOop but all vtables start at
    // the same place. The cast is to avoid virtual call and assertion.
    // See also LinkResolver::runtime_resolve_virtual_method.
    instanceKlass* inst = (instanceKlass*)Klass::cast(receiver_klass());
    DEBUG_ONLY(inst->verify_vtable_index(vtable_index));
    methodOop m_oop = inst->method_at_vtable(vtable_index);
    return methodHandle(THREAD, m_oop);

  } else {
    // perform interface dispatch
    int itable_index = klassItable::compute_itable_index(m());
    guarantee(itable_index >= 0, "valid itable index");
    instanceKlass* inst = instanceKlass::cast(receiver_klass());
    methodOop m_oop = inst->method_at_itable(m->method_holder(), itable_index, THREAD);
    return methodHandle(THREAD, m_oop);
  }
}

void MethodHandles::verify_DirectMethodHandle(Handle mh, methodHandle m, TRAPS) {
  // Verify type.
  Handle mtype(THREAD, java_dyn_MethodHandle::type(mh()));
  verify_method_type(m, mtype, false, KlassHandle(), CHECK);

  // Verify vmslots.
  if (java_dyn_MethodHandle::vmslots(mh()) != m->size_of_parameters()) {
    THROW_MSG(vmSymbols::java_lang_InternalError(), "bad vmslots in DMH");
  }
}

void MethodHandles::init_DirectMethodHandle(Handle mh, methodHandle m, bool do_dispatch, TRAPS) {
  // Check arguments.
  if (mh.is_null() || m.is_null() ||
      (!do_dispatch && m->is_abstract())) {
    THROW(vmSymbols::java_lang_InternalError());
  }

  java_dyn_MethodHandle::init_vmslots(mh());

  if (VerifyMethodHandles) {
    // The privileged code which invokes this routine should not make
    // a mistake about types, but it's better to verify.
    verify_DirectMethodHandle(mh, m, CHECK);
  }

  // Finally, after safety checks are done, link to the target method.
  // We will follow the same path as the latter part of
  // InterpreterRuntime::resolve_invoke(), which first finds the method
  // and then decides how to populate the constant pool cache entry
  // that links the interpreter calls to the method.  We need the same
  // bits, and will use the same calling sequence code.

  int vmindex = methodOopDesc::garbage_vtable_index;
  oop vmtarget = NULL;

  instanceKlass::cast(m->method_holder())->link_class(CHECK);

  MethodHandleEntry* me = NULL;
  if (do_dispatch && Klass::cast(m->method_holder())->is_interface()) {
    // We are simulating an invokeinterface instruction.
    // (We might also be simulating an invokevirtual on a miranda method,
    // but it is safe to treat it as an invokeinterface.)
    assert(!m->can_be_statically_bound(), "no final methods on interfaces");
    vmindex = klassItable::compute_itable_index(m());
    assert(vmindex >= 0, "(>=0) == do_dispatch");
    // Set up same bits as ConstantPoolCacheEntry::set_interface_call().
    vmtarget = m->method_holder(); // the interface
    me = MethodHandles::entry(MethodHandles::_invokeinterface_mh);
  } else if (!do_dispatch || m->can_be_statically_bound()) {
    // We are simulating an invokestatic or invokespecial instruction.
    // Set up the method pointer, just like ConstantPoolCacheEntry::set_method().
    vmtarget = m();
    // this does not help dispatch, but it will make it possible to parse this MH:
    vmindex  = methodOopDesc::nonvirtual_vtable_index;
    assert(vmindex < 0, "(>=0) == do_dispatch");
    if (!m->is_static()) {
      me = MethodHandles::entry(MethodHandles::_invokespecial_mh);
    } else {
      me = MethodHandles::entry(MethodHandles::_invokestatic_mh);
      // Part of the semantics of a static call is an initialization barrier.
      // For a DMH, it is done now, when the handle is created.
      Klass* k = Klass::cast(m->method_holder());
      if (k->should_be_initialized()) {
        k->initialize(CHECK);
      }
    }
  } else {
    // We are simulating an invokevirtual instruction.
    // Set up the vtable index, just like ConstantPoolCacheEntry::set_method().
    // The key logic is LinkResolver::runtime_resolve_virtual_method.
    vmindex  = m->vtable_index();
    vmtarget = m->method_holder();
    me = MethodHandles::entry(MethodHandles::_invokevirtual_mh);
  }

  if (me == NULL) { THROW(vmSymbols::java_lang_InternalError()); }

  sun_dyn_DirectMethodHandle::set_vmtarget(mh(), vmtarget);
  sun_dyn_DirectMethodHandle::set_vmindex(mh(),  vmindex);
  DEBUG_ONLY(int flags; klassOop rlimit);
  assert(MethodHandles::decode_method(mh(), rlimit, flags) == m(),
         "properly stored for later decoding");
  DEBUG_ONLY(bool actual_do_dispatch = ((flags & _dmf_does_dispatch) != 0));
  assert(!(actual_do_dispatch && !do_dispatch),
         "do not perform dispatch if !do_dispatch specified");
  assert(actual_do_dispatch == (vmindex >= 0), "proper later decoding of do_dispatch");
  assert(decode_MethodHandle_stack_pushes(mh()) == 0, "DMH does not move stack");

  // Done!
  java_dyn_MethodHandle::set_vmentry(mh(), me);
}

void MethodHandles::verify_BoundMethodHandle_with_receiver(Handle mh,
                                                           methodHandle m,
                                                           TRAPS) {
  // Verify type.
  oop receiver = sun_dyn_BoundMethodHandle::argument(mh());
  Handle mtype(THREAD, java_dyn_MethodHandle::type(mh()));
  KlassHandle bound_recv_type;
  if (receiver != NULL)  bound_recv_type = KlassHandle(THREAD, receiver->klass());
  verify_method_type(m, mtype, true, bound_recv_type, CHECK);

  int receiver_pos = m->size_of_parameters() - 1;

  // Verify MH.vmargslot, which should point at the bound receiver.
  verify_vmargslot(mh, -1, sun_dyn_BoundMethodHandle::vmargslot(mh()), CHECK);
  //verify_vmslots(mh, CHECK);

  // Verify vmslots.
  if (java_dyn_MethodHandle::vmslots(mh()) != receiver_pos) {
    THROW_MSG(vmSymbols::java_lang_InternalError(), "bad vmslots in BMH (receiver)");
  }
}

// Initialize a BMH with a receiver bound directly to a methodOop.
void MethodHandles::init_BoundMethodHandle_with_receiver(Handle mh,
                                                         methodHandle original_m,
                                                         KlassHandle receiver_limit,
                                                         int decode_flags,
                                                         TRAPS) {
  // Check arguments.
  if (mh.is_null() || original_m.is_null()) {
    THROW(vmSymbols::java_lang_InternalError());
  }

  KlassHandle receiver_klass;
  {
    oop receiver_oop = sun_dyn_BoundMethodHandle::argument(mh());
    if (receiver_oop != NULL)
      receiver_klass = KlassHandle(THREAD, receiver_oop->klass());
  }
  methodHandle m = dispatch_decoded_method(original_m,
                                           receiver_limit, decode_flags,
                                           receiver_klass,
                                           CHECK);
  if (m.is_null())      { THROW(vmSymbols::java_lang_InternalError()); }
  if (m->is_abstract()) { THROW(vmSymbols::java_lang_AbstractMethodError()); }

  java_dyn_MethodHandle::init_vmslots(mh());

  if (VerifyMethodHandles) {
    verify_BoundMethodHandle_with_receiver(mh, m, CHECK);
  }

  sun_dyn_BoundMethodHandle::set_vmtarget(mh(), m());

  DEBUG_ONLY(int junk; klassOop junk2);
  assert(MethodHandles::decode_method(mh(), junk2, junk) == m(), "properly stored for later decoding");
  assert(decode_MethodHandle_stack_pushes(mh()) == 1, "BMH pushes one stack slot");

  // Done!
  java_dyn_MethodHandle::set_vmentry(mh(), MethodHandles::entry(MethodHandles::_bound_ref_direct_mh));
}

void MethodHandles::verify_BoundMethodHandle(Handle mh, Handle target, int argnum,
                                             bool direct_to_method, TRAPS) {
  Handle ptype_handle(THREAD,
                           java_dyn_MethodType::ptype(java_dyn_MethodHandle::type(target()), argnum));
  KlassHandle ptype_klass;
  BasicType ptype = java_lang_Class::as_BasicType(ptype_handle(), &ptype_klass);
  int slots_pushed = type2size[ptype];

  oop argument = sun_dyn_BoundMethodHandle::argument(mh());

  const char* err = NULL;

  switch (ptype) {
  case T_OBJECT:
    if (argument != NULL)
      // we must implicitly convert from the arg type to the outgoing ptype
      err = check_argument_type_change(T_OBJECT, argument->klass(), ptype, ptype_klass(), argnum);
    break;

  case T_ARRAY: case T_VOID:
    assert(false, "array, void do not appear here");
  default:
    if (ptype != T_INT && !is_subword_type(ptype)) {
      err = "unexpected parameter type";
      break;
    }
    // check subrange of Integer.value, if necessary
    if (argument == NULL || argument->klass() != SystemDictionary::Integer_klass()) {
      err = "bound integer argument must be of type java.lang.Integer";
      break;
    }
    if (ptype != T_INT) {
      int value_offset = java_lang_boxing_object::value_offset_in_bytes(T_INT);
      jint value = argument->int_field(value_offset);
      int vminfo = adapter_subword_vminfo(ptype);
      jint subword = truncate_subword_from_vminfo(value, vminfo);
      if (value != subword) {
        err = "bound subword value does not fit into the subword type";
        break;
      }
    }
    break;
  case T_FLOAT:
  case T_DOUBLE:
  case T_LONG:
    {
      // we must implicitly convert from the unboxed arg type to the outgoing ptype
      BasicType argbox = java_lang_boxing_object::basic_type(argument);
      if (argbox != ptype) {
        err = check_argument_type_change(T_OBJECT, (argument == NULL
                                                    ? SystemDictionary::Object_klass()
                                                    : argument->klass()),
                                         ptype, ptype_klass(), argnum);
        assert(err != NULL, "this must be an error");
      }
      break;
    }
  }

  if (err == NULL) {
    DEBUG_ONLY(int this_pushes = decode_MethodHandle_stack_pushes(mh()));
    if (direct_to_method) {
      assert(this_pushes == slots_pushed, "BMH pushes one or two stack slots");
      assert(slots_pushed <= MethodHandlePushLimit, "");
    } else {
      int target_pushes = decode_MethodHandle_stack_pushes(target());
      assert(this_pushes == slots_pushed + target_pushes, "BMH stack motion must be correct");
      // do not blow the stack; use a Java-based adapter if this limit is exceeded
      // FIXME
      // if (slots_pushed + target_pushes > MethodHandlePushLimit)
      //   err = "too many bound parameters";
    }
  }

  if (err == NULL) {
    // Verify the rest of the method type.
    err = check_method_type_insertion(java_dyn_MethodHandle::type(mh()),
                                      argnum, ptype_handle(),
                                      java_dyn_MethodHandle::type(target()));
  }

  if (err != NULL) {
    THROW_MSG(vmSymbols::java_lang_InternalError(), err);
  }
}

void MethodHandles::init_BoundMethodHandle(Handle mh, Handle target, int argnum, TRAPS) {
  // Check arguments.
  if (mh.is_null() || target.is_null() || !java_dyn_MethodHandle::is_instance(target())) {
    THROW(vmSymbols::java_lang_InternalError());
  }

  java_dyn_MethodHandle::init_vmslots(mh());

  if (VerifyMethodHandles) {
    int insert_after = argnum - 1;
    verify_vmargslot(mh, insert_after, sun_dyn_BoundMethodHandle::vmargslot(mh()), CHECK);
    verify_vmslots(mh, CHECK);
  }

  // Get bound type and required slots.
  oop ptype_oop = java_dyn_MethodType::ptype(java_dyn_MethodHandle::type(target()), argnum);
  BasicType ptype = java_lang_Class::as_BasicType(ptype_oop);
  int slots_pushed = type2size[ptype];

  // If (a) the target is a direct non-dispatched method handle,
  // or (b) the target is a dispatched direct method handle and we
  // are binding the receiver, cut out the middle-man.
  // Do this by decoding the DMH and using its methodOop directly as vmtarget.
  bool direct_to_method = false;
  if (OptimizeMethodHandles &&
      target->klass() == SystemDictionary::DirectMethodHandle_klass() &&
      (argnum == 0 || sun_dyn_DirectMethodHandle::vmindex(target()) < 0)) {
    int decode_flags = 0; klassOop receiver_limit_oop = NULL;
    methodHandle m(THREAD, decode_method(target(), receiver_limit_oop, decode_flags));
    if (m.is_null()) { THROW_MSG(vmSymbols::java_lang_InternalError(), "DMH failed to decode"); }
    DEBUG_ONLY(int m_vmslots = m->size_of_parameters() - slots_pushed); // pos. of 1st arg.
    assert(sun_dyn_BoundMethodHandle::vmslots(mh()) == m_vmslots, "type w/ m sig");
    if (argnum == 0 && (decode_flags & _dmf_has_receiver) != 0) {
      KlassHandle receiver_limit(THREAD, receiver_limit_oop);
      init_BoundMethodHandle_with_receiver(mh, m,
                                           receiver_limit, decode_flags,
                                           CHECK);
      return;
    }

    // Even if it is not a bound receiver, we still might be able
    // to bind another argument and still invoke the methodOop directly.
    if (!(decode_flags & _dmf_does_dispatch)) {
      direct_to_method = true;
      sun_dyn_BoundMethodHandle::set_vmtarget(mh(), m());
    }
  }
  if (!direct_to_method)
    sun_dyn_BoundMethodHandle::set_vmtarget(mh(), target());

  if (VerifyMethodHandles) {
    verify_BoundMethodHandle(mh, target, argnum, direct_to_method, CHECK);
  }

  // Next question:  Is this a ref, int, or long bound value?
  MethodHandleEntry* me = NULL;
  if (ptype == T_OBJECT) {
    if (direct_to_method)  me = MethodHandles::entry(_bound_ref_direct_mh);
    else                   me = MethodHandles::entry(_bound_ref_mh);
  } else if (slots_pushed == 2) {
    if (direct_to_method)  me = MethodHandles::entry(_bound_long_direct_mh);
    else                   me = MethodHandles::entry(_bound_long_mh);
  } else if (slots_pushed == 1) {
    if (direct_to_method)  me = MethodHandles::entry(_bound_int_direct_mh);
    else                   me = MethodHandles::entry(_bound_int_mh);
  } else {
    assert(false, "");
  }

  // Done!
  java_dyn_MethodHandle::set_vmentry(mh(), me);
}

static void throw_InternalError_for_bad_conversion(int conversion, const char* err, TRAPS) {
  char msg[200];
  jio_snprintf(msg, sizeof(msg), "bad adapter (conversion=0x%08x): %s", conversion, err);
  THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), msg);
}

void MethodHandles::verify_AdapterMethodHandle(Handle mh, int argnum, TRAPS) {
  jint conversion = sun_dyn_AdapterMethodHandle::conversion(mh());
  int  argslot    = sun_dyn_AdapterMethodHandle::vmargslot(mh());

  verify_vmargslot(mh, argnum, argslot, CHECK);
  verify_vmslots(mh, CHECK);

  jint conv_op    = adapter_conversion_op(conversion);
  if (!conv_op_valid(conv_op)) {
    throw_InternalError_for_bad_conversion(conversion, "unknown conversion op", THREAD);
    return;
  }
  EntryKind ek = adapter_entry_kind(conv_op);

  int stack_move = adapter_conversion_stack_move(conversion);
  BasicType src  = adapter_conversion_src_type(conversion);
  BasicType dest = adapter_conversion_dest_type(conversion);
  int vminfo     = adapter_conversion_vminfo(conversion); // should be zero

  Handle argument(THREAD,  sun_dyn_AdapterMethodHandle::argument(mh()));
  Handle target(THREAD,    sun_dyn_AdapterMethodHandle::vmtarget(mh()));
  Handle src_mtype(THREAD, java_dyn_MethodHandle::type(mh()));
  Handle dst_mtype(THREAD, java_dyn_MethodHandle::type(target()));

  const char* err = NULL;

  if (err == NULL) {
    // Check that the correct argument is supplied, but only if it is required.
    switch (ek) {
    case _adapter_check_cast:     // target type of cast
    case _adapter_ref_to_prim:    // wrapper type from which to unbox
    case _adapter_prim_to_ref:    // wrapper type to box into
    case _adapter_collect_args:   // array type to collect into
    case _adapter_spread_args:    // array type to spread from
      if (!java_lang_Class::is_instance(argument())
          || java_lang_Class::is_primitive(argument()))
        { err = "adapter requires argument of type java.lang.Class"; break; }
      if (ek == _adapter_collect_args ||
          ek == _adapter_spread_args) {
        // Make sure it is a suitable collection type.  (Array, for now.)
        Klass* ak = Klass::cast(java_lang_Class::as_klassOop(argument()));
        if (!ak->oop_is_objArray()) {
          { err = "adapter requires argument of type java.lang.Class<Object[]>"; break; }
        }
      }
      break;
    case _adapter_flyby:
    case _adapter_ricochet:
      if (!java_dyn_MethodHandle::is_instance(argument()))
        { err = "MethodHandle adapter argument required"; break; }
      break;
    default:
      if (argument.not_null())
        { err = "adapter has spurious argument"; break; }
      break;
    }
  }

  if (err == NULL) {
    // Check that the src/dest types are supplied if needed.
    switch (ek) {
    case _adapter_check_cast:
      if (src != T_OBJECT || dest != T_OBJECT) {
        err = "adapter requires object src/dest conversion subfields";
      }
      break;
    case _adapter_prim_to_prim:
      if (!is_java_primitive(src) || !is_java_primitive(dest) || src == dest) {
        err = "adapter requires primitive src/dest conversion subfields"; break;
      }
      if ( (src == T_FLOAT || src == T_DOUBLE) && !(dest == T_FLOAT || dest == T_DOUBLE) ||
          !(src == T_FLOAT || src == T_DOUBLE) &&  (dest == T_FLOAT || dest == T_DOUBLE)) {
        err = "adapter cannot convert beween floating and fixed-point"; break;
      }
      break;
    case _adapter_ref_to_prim:
      if (src != T_OBJECT || !is_java_primitive(dest)
          || argument() != Klass::cast(SystemDictionary::box_klass(dest))->java_mirror()) {
        err = "adapter requires primitive dest conversion subfield"; break;
      }
      break;
    case _adapter_prim_to_ref:
      if (!is_java_primitive(src) || dest != T_OBJECT
          || argument() != Klass::cast(SystemDictionary::box_klass(src))->java_mirror()) {
        err = "adapter requires primitive src conversion subfield"; break;
      }
      break;
    case _adapter_swap_args:
    case _adapter_rot_args:
      {
        if (!src || src != dest) {
          err = "adapter requires src/dest conversion subfields for swap"; break;
        }
        int swap_size = type2size[src];
        oop src_mtype  = sun_dyn_AdapterMethodHandle::type(mh());
        oop dest_mtype = sun_dyn_AdapterMethodHandle::type(target());
        int slot_limit = sun_dyn_AdapterMethodHandle::vmslots(target());
        int src_slot   = argslot;
        int dest_slot  = vminfo;
        bool rotate_up = (src_slot > dest_slot); // upward rotation
        int src_arg    = argnum;
        int dest_arg   = argument_slot_to_argnum(dest_mtype, dest_slot);
        verify_vmargslot(mh, dest_arg, dest_slot, CHECK);
        if (!(dest_slot >= src_slot + swap_size) &&
            !(src_slot >= dest_slot + swap_size)) {
          err = "source, destination slots must be distinct";
        } else if (ek == _adapter_swap_args && !(src_slot > dest_slot)) {
          err = "source of swap must be deeper in stack";
        } else if (ek == _adapter_swap_args) {
          err = check_argument_type_change(java_dyn_MethodType::ptype(src_mtype, dest_arg),
                                           java_dyn_MethodType::ptype(dest_mtype, src_arg),
                                           dest_arg);
        } else if (ek == _adapter_rot_args) {
          if (rotate_up) {
            assert((src_slot > dest_slot) && (src_arg < dest_arg), "");
            // rotate up: [dest_slot..src_slot-ss] --> [dest_slot+ss..src_slot]
            // that is:   [src_arg+1..dest_arg] --> [src_arg..dest_arg-1]
            for (int i = src_arg+1; i <= dest_arg && err == NULL; i++) {
              err = check_argument_type_change(java_dyn_MethodType::ptype(src_mtype, i),
                                               java_dyn_MethodType::ptype(dest_mtype, i-1),
                                               i);
            }
          } else { // rotate down
            assert((src_slot < dest_slot) && (src_arg > dest_arg), "");
            // rotate down: [src_slot+ss..dest_slot] --> [src_slot..dest_slot-ss]
            // that is:     [dest_arg..src_arg-1] --> [dst_arg+1..src_arg]
            for (int i = dest_arg; i <= src_arg-1 && err == NULL; i++) {
              err = check_argument_type_change(java_dyn_MethodType::ptype(src_mtype, i),
                                               java_dyn_MethodType::ptype(dest_mtype, i+1),
                                               i);
            }
          }
        }
        if (err == NULL)
          err = check_argument_type_change(java_dyn_MethodType::ptype(src_mtype, src_arg),
                                           java_dyn_MethodType::ptype(dest_mtype, dest_arg),
                                           src_arg);
      }
      break;
    case _adapter_collect_args:
    case _adapter_spread_args:
      {
        BasicType coll_type = (ek == _adapter_collect_args) ? dest : src;
        BasicType elem_type = (ek == _adapter_collect_args) ? src : dest;
        if (coll_type != T_OBJECT || elem_type != T_OBJECT) {
          err = "adapter requires src/dest subfields"; break;
          // later:
          // - consider making coll be a primitive array
          // - consider making coll be a heterogeneous collection
        }
      }
      break;
    default:
      if (src != 0 || dest != 0) {
        err = "adapter has spurious src/dest conversion subfields"; break;
      }
      break;
    }
  }

  if (err == NULL) {
    // Check the stack_move subfield.
    // It must always report the net change in stack size, positive or negative.
    int slots_pushed = stack_move / stack_move_unit();
    switch (ek) {
    case _adapter_prim_to_prim:
    case _adapter_ref_to_prim:
    case _adapter_prim_to_ref:
      if (slots_pushed != type2size[dest] - type2size[src]) {
        err = "wrong stack motion for primitive conversion";
      }
      break;
    case _adapter_dup_args:
      if (slots_pushed <= 0) {
        err = "adapter requires conversion subfield slots_pushed > 0";
      }
      break;
    case _adapter_drop_args:
      if (slots_pushed >= 0) {
        err = "adapter requires conversion subfield slots_pushed < 0";
      }
      break;
    case _adapter_collect_args:
      if (slots_pushed > 1) {
        err = "adapter requires conversion subfield slots_pushed <= 1";
      }
      break;
    case _adapter_spread_args:
      if (slots_pushed < -1) {
        err = "adapter requires conversion subfield slots_pushed >= -1";
      }
      break;
    default:
      if (stack_move != 0) {
        err = "adapter has spurious stack_move conversion subfield";
      }
      break;
    }
    if (err == NULL && stack_move != slots_pushed * stack_move_unit()) {
      err = "stack_move conversion subfield must be multiple of stack_move_unit";
    }
  }

  if (err == NULL) {
    // Make sure this adapter does not push too deeply.
    int slots_pushed = stack_move / stack_move_unit();
    int this_vmslots = java_dyn_MethodHandle::vmslots(mh());
    int target_vmslots = java_dyn_MethodHandle::vmslots(target());
    if (slots_pushed != (target_vmslots - this_vmslots)) {
      err = "stack_move inconsistent with previous and current MethodType vmslots";
    } else if (slots_pushed > 0)  {
      // verify stack_move against MethodHandlePushLimit
      int target_pushes = decode_MethodHandle_stack_pushes(target());
      // do not blow the stack; use a Java-based adapter if this limit is exceeded
      if (slots_pushed + target_pushes > MethodHandlePushLimit) {
        err = "adapter pushes too many parameters";
      }
    }

    // While we're at it, check that the stack motion decoder works:
    DEBUG_ONLY(int target_pushes = decode_MethodHandle_stack_pushes(target()));
    DEBUG_ONLY(int this_pushes = decode_MethodHandle_stack_pushes(mh()));
    assert(this_pushes == slots_pushed + target_pushes, "AMH stack motion must be correct");
  }

  if (err == NULL && vminfo != 0) {
    switch (ek) {
      case _adapter_swap_args:
      case _adapter_rot_args:
        break;                // OK
    default:
      err = "vminfo subfield is reserved to the JVM";
    }
  }

  // Do additional ad hoc checks.
  if (err == NULL) {
    switch (ek) {
    case _adapter_retype_only:
      err = check_method_type_passthrough(src_mtype(), dst_mtype(), false);
      break;

    case _adapter_retype_raw:
      err = check_method_type_passthrough(src_mtype(), dst_mtype(), true);
      break;

    case _adapter_check_cast:
      {
        // The actual value being checked must be a reference:
        err = check_argument_type_change(java_dyn_MethodType::ptype(src_mtype(), argnum),
                                         object_java_mirror(), argnum);
        if (err != NULL)  break;

        // The output of the cast must fit with the destination argument:
        Handle cast_class = argument;
        err = check_method_type_conversion(src_mtype(),
                                           argnum, cast_class(),
                                           dst_mtype());
      }
      break;

      // %%% TO DO: continue in remaining cases to verify src/dst_mtype if VerifyMethodHandles
    }
  }

  if (err != NULL) {
    throw_InternalError_for_bad_conversion(conversion, err, THREAD);
    return;
  }

}

void MethodHandles::init_AdapterMethodHandle(Handle mh, Handle target, int argnum, TRAPS) {
  oop  argument   = sun_dyn_AdapterMethodHandle::argument(mh());
  int  argslot    = sun_dyn_AdapterMethodHandle::vmargslot(mh());
  jint conversion = sun_dyn_AdapterMethodHandle::conversion(mh());
  jint conv_op    = adapter_conversion_op(conversion);

  // adjust the adapter code to the internal EntryKind enumeration:
  EntryKind ek_orig = adapter_entry_kind(conv_op);
  EntryKind ek_opt  = ek_orig;  // may be optimized

  // Finalize the vmtarget field (Java initialized it to null).
  if (!java_dyn_MethodHandle::is_instance(target())) {
    throw_InternalError_for_bad_conversion(conversion, "bad target", THREAD);
    return;
  }
  sun_dyn_AdapterMethodHandle::set_vmtarget(mh(), target());

  if (VerifyMethodHandles) {
    verify_AdapterMethodHandle(mh, argnum, CHECK);
  }

  int stack_move = adapter_conversion_stack_move(conversion);
  BasicType src  = adapter_conversion_src_type(conversion);
  BasicType dest = adapter_conversion_dest_type(conversion);
  int vminfo     = adapter_conversion_vminfo(conversion); // should be zero

  const char* err = NULL;

  // Now it's time to finish the case analysis and pick a MethodHandleEntry.
  switch (ek_orig) {
  case _adapter_retype_only:
  case _adapter_retype_raw:
  case _adapter_check_cast:
  case _adapter_dup_args:
  case _adapter_drop_args:
    // these work fine via general case code
    break;

  case _adapter_prim_to_prim:
    {
      // Non-subword cases are {int,float,long,double} -> {int,float,long,double}.
      // And, the {float,double} -> {int,long} cases must be handled by Java.
      switch (type2size[src] *4+ type2size[dest]) {
      case 1 *4+ 1:
        assert(src == T_INT || is_subword_type(src), "source is not float");
        // Subword-related cases are int -> {boolean,byte,char,short}.
        ek_opt = _adapter_opt_i2i;
        vminfo = adapter_subword_vminfo(dest);
        break;
      case 2 *4+ 1:
        if (src == T_LONG && (dest == T_INT || is_subword_type(dest))) {
          ek_opt = _adapter_opt_l2i;
          vminfo = adapter_subword_vminfo(dest);
        } else if (src == T_DOUBLE && dest == T_FLOAT) {
          ek_opt = _adapter_opt_d2f;
        } else {
          assert(false, "");
        }
        break;
      case 1 *4+ 2:
        if (src == T_INT && dest == T_LONG) {
          ek_opt = _adapter_opt_i2l;
        } else if (src == T_FLOAT && dest == T_DOUBLE) {
          ek_opt = _adapter_opt_f2d;
        } else {
          assert(false, "");
        }
        break;
      default:
        assert(false, "");
        break;
      }
    }
    break;

  case _adapter_ref_to_prim:
    {
      switch (type2size[dest]) {
      case 1:
        ek_opt = _adapter_opt_unboxi;
        vminfo = adapter_subword_vminfo(dest);
        break;
      case 2:
        ek_opt = _adapter_opt_unboxl;
        break;
      default:
        assert(false, "");
        break;
      }
    }
    break;

  case _adapter_prim_to_ref:
    goto throw_not_impl;        // allocates, hence could block

  case _adapter_swap_args:
  case _adapter_rot_args:
    {
      int swap_slots = type2size[src];
      int slot_limit = sun_dyn_AdapterMethodHandle::vmslots(mh());
      int src_slot   = argslot;
      int dest_slot  = vminfo;
      int rotate     = (ek_orig == _adapter_swap_args) ? 0 : (src_slot > dest_slot) ? 1 : -1;
      switch (swap_slots) {
      case 1:
        ek_opt = (!rotate    ? _adapter_opt_swap_1 :
                  rotate > 0 ? _adapter_opt_rot_1_up : _adapter_opt_rot_1_down);
        break;
      case 2:
        ek_opt = (!rotate    ? _adapter_opt_swap_2 :
                  rotate > 0 ? _adapter_opt_rot_2_up : _adapter_opt_rot_2_down);
        break;
      default:
        assert(false, "");
        break;
      }
    }
    break;

  case _adapter_collect_args:
    goto throw_not_impl;        // allocates, hence could block

  case _adapter_spread_args:
    {
      // vminfo will be the required length of the array
      int slots_pushed = stack_move / stack_move_unit();
      int array_size   = slots_pushed + 1;
      assert(array_size >= 0, "");
      vminfo = array_size;
      switch (array_size) {
      case 0:   ek_opt = _adapter_opt_spread_0;       break;
      case 1:   ek_opt = _adapter_opt_spread_1;       break;
      default:  ek_opt = _adapter_opt_spread_more;    break;
      }
      if ((vminfo & CONV_VMINFO_MASK) != vminfo)
        goto throw_not_impl;    // overflow
    }
    break;

  case _adapter_flyby:
  case _adapter_ricochet:
    goto throw_not_impl;        // runs Java code, hence could block

  default:
    // should have failed much earlier; must be a missing case here
    assert(false, "incomplete switch");
    // and fall through:

  throw_not_impl:
    // FIXME: these adapters are NYI
    err = "adapter not yet implemented in the JVM";
    break;
  }

  if (err != NULL) {
    throw_InternalError_for_bad_conversion(conversion, err, THREAD);
    return;
  }

  // Rebuild the conversion value; maybe parts of it were changed.
  jint new_conversion = adapter_conversion(conv_op, src, dest, stack_move, vminfo);

  // Finalize the conversion field.  (Note that it is final to Java code.)
  sun_dyn_AdapterMethodHandle::set_conversion(mh(), new_conversion);

  // Done!
  java_dyn_MethodHandle::set_vmentry(mh(), entry(ek_opt));

  // There should be enough memory barriers on exit from native methods
  // to ensure that the MH is fully initialized to all threads before
  // Java code can publish it in global data structures.
}

//
// Here are the native methods on sun.dyn.MethodHandleImpl.
// They are the private interface between this JVM and the HotSpot-specific
// Java code that implements JSR 292 method handles.
//
// Note:  We use a JVM_ENTRY macro to define each of these, for this is the way
// that intrinsic (non-JNI) native methods are defined in HotSpot.
//

// direct method handles for invokestatic or invokespecial
// void init(DirectMethodHandle self, MemberName ref, boolean doDispatch, Class<?> caller);
JVM_ENTRY(void, MHI_init_DMH(JNIEnv *env, jobject igcls, jobject mh_jh,
                             jobject target_jh, jboolean do_dispatch, jobject caller_jh)) {
  ResourceMark rm;              // for error messages

  // This is the guy we are initializing:
  if (mh_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
  Handle mh(THREAD, JNIHandles::resolve_non_null(mh_jh));

  // Early returns out of this method leave the DMH in an unfinished state.
  assert(java_dyn_MethodHandle::vmentry(mh()) == NULL, "must be safely null");

  // which method are we really talking about?
  if (target_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
  oop target_oop = JNIHandles::resolve_non_null(target_jh);
  if (sun_dyn_MemberName::is_instance(target_oop) &&
      sun_dyn_MemberName::vmindex(target_oop) == VM_INDEX_UNINITIALIZED) {
    Handle mname(THREAD, target_oop);
    MethodHandles::resolve_MemberName(mname, CHECK);
    target_oop = mname(); // in case of GC
  }

  int decode_flags = 0; klassOop receiver_limit = NULL;
  methodHandle m(THREAD,
                 MethodHandles::decode_method(target_oop,
                                              receiver_limit, decode_flags));
  if (m.is_null()) { THROW_MSG(vmSymbols::java_lang_InternalError(), "no such method"); }

  // The trusted Java code that calls this method should already have performed
  // access checks on behalf of the given caller.  But, we can verify this.
  if (VerifyMethodHandles && caller_jh != NULL) {
    KlassHandle caller(THREAD, java_lang_Class::as_klassOop(JNIHandles::resolve_non_null(caller_jh)));
    // If this were a bytecode, the first access check would be against
    // the "reference class" mentioned in the CONSTANT_Methodref.
    // We don't know at this point which class that was, and if we
    // check against m.method_holder we might get the wrong answer.
    // So we just make sure to handle this check when the resolution
    // happens, when we call resolve_MemberName.
    //
    // (A public class can inherit public members from private supers,
    // and it would be wrong to check access against the private super
    // if the original symbolic reference was against the public class.)
    //
    // If there were a bytecode, the next step would be to lookup the method
    // in the reference class, then then check the method's access bits.
    // Emulate LinkResolver::check_method_accessability.
    klassOop resolved_klass = m->method_holder();
    if (!Reflection::verify_field_access(caller->as_klassOop(),
                                         resolved_klass, resolved_klass,
                                         m->access_flags(),
                                         true)) {
      // %%% following cutout belongs in Reflection::verify_field_access?
      bool same_pm = Reflection::is_same_package_member(caller->as_klassOop(),
                                                        resolved_klass, THREAD);
      if (!same_pm) {
        THROW_MSG(vmSymbols::java_lang_InternalError(), m->name_and_sig_as_C_string());
      }
    }
  }

  MethodHandles::init_DirectMethodHandle(mh, m, (do_dispatch != JNI_FALSE), CHECK);
}
JVM_END

// bound method handles
JVM_ENTRY(void, MHI_init_BMH(JNIEnv *env, jobject igcls, jobject mh_jh,
                             jobject target_jh, int argnum)) {
  ResourceMark rm;              // for error messages

  // This is the guy we are initializing:
  if (mh_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
  Handle mh(THREAD, JNIHandles::resolve_non_null(mh_jh));

  // Early returns out of this method leave the BMH in an unfinished state.
  assert(java_dyn_MethodHandle::vmentry(mh()) == NULL, "must be safely null");

  if (target_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
  Handle target(THREAD, JNIHandles::resolve_non_null(target_jh));

  if (!java_dyn_MethodHandle::is_instance(target())) {
    // Target object is a reflective method.  (%%% Do we need this alternate path?)
    Untested("init_BMH of non-MH");
    if (argnum != 0) { THROW(vmSymbols::java_lang_InternalError()); }
    int decode_flags = 0; klassOop receiver_limit_oop = NULL;
    methodHandle m(THREAD,
                   MethodHandles::decode_method(target(),
                                                receiver_limit_oop,
                                                decode_flags));
    KlassHandle receiver_limit(THREAD, receiver_limit_oop);
    MethodHandles::init_BoundMethodHandle_with_receiver(mh, m,
                                                       receiver_limit,
                                                       decode_flags,
                                                       CHECK);
    return;
  }

  // Build a BMH on top of a DMH or another BMH:
  MethodHandles::init_BoundMethodHandle(mh, target, argnum, CHECK);
}
JVM_END

// adapter method handles
JVM_ENTRY(void, MHI_init_AMH(JNIEnv *env, jobject igcls, jobject mh_jh,
                             jobject target_jh, int argnum)) {
  // This is the guy we are initializing:
  if (mh_jh == NULL || target_jh == NULL) {
    THROW(vmSymbols::java_lang_InternalError());
  }
  Handle mh(THREAD, JNIHandles::resolve_non_null(mh_jh));
  Handle target(THREAD, JNIHandles::resolve_non_null(target_jh));

  // Early returns out of this method leave the AMH in an unfinished state.
  assert(java_dyn_MethodHandle::vmentry(mh()) == NULL, "must be safely null");

  MethodHandles::init_AdapterMethodHandle(mh, target, argnum, CHECK);
}
JVM_END

// method type forms
JVM_ENTRY(void, MHI_init_MT(JNIEnv *env, jobject igcls, jobject erased_jh)) {
  if (erased_jh == NULL)  return;
  if (TraceMethodHandles) {
    tty->print("creating MethodType form ");
    if (WizardMode || Verbose) {   // Warning: this calls Java code on the MH!
      // call Object.toString()
      symbolOop name = vmSymbols::toString_name(), sig = vmSymbols::void_string_signature();
      JavaCallArguments args(Handle(THREAD, JNIHandles::resolve_non_null(erased_jh)));
      JavaValue result(T_OBJECT);
      JavaCalls::call_virtual(&result, SystemDictionary::Object_klass(), name, sig,
                              &args, CHECK);
      Handle str(THREAD, (oop)result.get_jobject());
      java_lang_String::print(str, tty);
    }
    tty->cr();
  }
}
JVM_END

// debugging and reflection
JVM_ENTRY(jobject, MHI_getTarget(JNIEnv *env, jobject igcls, jobject mh_jh, jint format)) {
  Handle mh(THREAD, JNIHandles::resolve(mh_jh));
  if (!java_dyn_MethodHandle::is_instance(mh())) {
    THROW_NULL(vmSymbols::java_lang_IllegalArgumentException());
  }
  oop target = MethodHandles::encode_target(mh, format, CHECK_NULL);
  return JNIHandles::make_local(THREAD, target);
}
JVM_END

JVM_ENTRY(jint, MHI_getConstant(JNIEnv *env, jobject igcls, jint which)) {
  switch (which) {
  case MethodHandles::GC_JVM_PUSH_LIMIT:
    guarantee(MethodHandlePushLimit >= 2 && MethodHandlePushLimit <= 0xFF,
              "MethodHandlePushLimit parameter must be in valid range");
    return MethodHandlePushLimit;
  case MethodHandles::GC_JVM_STACK_MOVE_UNIT:
    // return number of words per slot, signed according to stack direction
    return MethodHandles::stack_move_unit();
  case MethodHandles::GC_CONV_OP_IMPLEMENTED_MASK:
    return MethodHandles::adapter_conversion_ops_supported_mask();
  }
  return 0;
}
JVM_END

#ifndef PRODUCT
#define EACH_NAMED_CON(template) \
    template(MethodHandles,GC_JVM_PUSH_LIMIT) \
    template(MethodHandles,GC_JVM_STACK_MOVE_UNIT) \
    template(MethodHandles,ETF_HANDLE_OR_METHOD_NAME) \
    template(MethodHandles,ETF_DIRECT_HANDLE) \
    template(MethodHandles,ETF_METHOD_NAME) \
    template(MethodHandles,ETF_REFLECT_METHOD) \
    template(sun_dyn_MemberName,MN_IS_METHOD) \
    template(sun_dyn_MemberName,MN_IS_CONSTRUCTOR) \
    template(sun_dyn_MemberName,MN_IS_FIELD) \
    template(sun_dyn_MemberName,MN_IS_TYPE) \
    template(sun_dyn_MemberName,MN_SEARCH_SUPERCLASSES) \
    template(sun_dyn_MemberName,MN_SEARCH_INTERFACES) \
    template(sun_dyn_MemberName,VM_INDEX_UNINITIALIZED) \
    template(sun_dyn_AdapterMethodHandle,OP_RETYPE_ONLY) \
    template(sun_dyn_AdapterMethodHandle,OP_RETYPE_RAW) \
    template(sun_dyn_AdapterMethodHandle,OP_CHECK_CAST) \
    template(sun_dyn_AdapterMethodHandle,OP_PRIM_TO_PRIM) \
    template(sun_dyn_AdapterMethodHandle,OP_REF_TO_PRIM) \
    template(sun_dyn_AdapterMethodHandle,OP_PRIM_TO_REF) \
    template(sun_dyn_AdapterMethodHandle,OP_SWAP_ARGS) \
    template(sun_dyn_AdapterMethodHandle,OP_ROT_ARGS) \
    template(sun_dyn_AdapterMethodHandle,OP_DUP_ARGS) \
    template(sun_dyn_AdapterMethodHandle,OP_DROP_ARGS) \
    template(sun_dyn_AdapterMethodHandle,OP_COLLECT_ARGS) \
    template(sun_dyn_AdapterMethodHandle,OP_SPREAD_ARGS) \
    template(sun_dyn_AdapterMethodHandle,OP_FLYBY) \
    template(sun_dyn_AdapterMethodHandle,OP_RICOCHET) \
    template(sun_dyn_AdapterMethodHandle,CONV_OP_LIMIT) \
    template(sun_dyn_AdapterMethodHandle,CONV_OP_MASK) \
    template(sun_dyn_AdapterMethodHandle,CONV_VMINFO_MASK) \
    template(sun_dyn_AdapterMethodHandle,CONV_VMINFO_SHIFT) \
    template(sun_dyn_AdapterMethodHandle,CONV_OP_SHIFT) \
    template(sun_dyn_AdapterMethodHandle,CONV_DEST_TYPE_SHIFT) \
    template(sun_dyn_AdapterMethodHandle,CONV_SRC_TYPE_SHIFT) \
    template(sun_dyn_AdapterMethodHandle,CONV_STACK_MOVE_SHIFT) \
    template(sun_dyn_AdapterMethodHandle,CONV_STACK_MOVE_MASK) \
    /*end*/

#define ONE_PLUS(scope,value) 1+
static const int con_value_count = EACH_NAMED_CON(ONE_PLUS) 0;
#define VALUE_COMMA(scope,value) scope::value,
static const int con_values[con_value_count+1] = { EACH_NAMED_CON(VALUE_COMMA) 0 };
#define STRING_NULL(scope,value) #value "\0"
static const char con_names[] = { EACH_NAMED_CON(STRING_NULL) };

#undef ONE_PLUS
#undef VALUE_COMMA
#undef STRING_NULL
#undef EACH_NAMED_CON
#endif

JVM_ENTRY(jint, MHI_getNamedCon(JNIEnv *env, jobject igcls, jint which, jobjectArray box_jh)) {
#ifndef PRODUCT
  if (which >= 0 && which < con_value_count) {
    int con = con_values[which];
    objArrayOop box = (objArrayOop) JNIHandles::resolve(box_jh);
    if (box != NULL && box->klass() == Universe::objectArrayKlassObj() && box->length() > 0) {
      const char* str = &con_names[0];
      for (int i = 0; i < which; i++)
        str += strlen(str) + 1;   // skip name and null
      oop name = java_lang_String::create_oop_from_str(str, CHECK_0);
      box->obj_at_put(0, name);
    }
    return con;
  }
#endif
  return 0;
}
JVM_END

// void init(MemberName self, AccessibleObject ref)
JVM_ENTRY(void, MHI_init_Mem(JNIEnv *env, jobject igcls, jobject mname_jh, jobject target_jh)) {
  if (mname_jh == NULL || target_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
  Handle mname(THREAD, JNIHandles::resolve_non_null(mname_jh));
  oop target_oop = JNIHandles::resolve_non_null(target_jh);
  MethodHandles::init_MemberName(mname(), target_oop);
}
JVM_END

// void expand(MemberName self)
JVM_ENTRY(void, MHI_expand_Mem(JNIEnv *env, jobject igcls, jobject mname_jh)) {
  if (mname_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
  Handle mname(THREAD, JNIHandles::resolve_non_null(mname_jh));
  MethodHandles::expand_MemberName(mname, 0, CHECK);
}
JVM_END

// void resolve(MemberName self, Class<?> caller)
JVM_ENTRY(void, MHI_resolve_Mem(JNIEnv *env, jobject igcls, jobject mname_jh, jclass caller_jh)) {
  if (mname_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
  Handle mname(THREAD, JNIHandles::resolve_non_null(mname_jh));

  // The trusted Java code that calls this method should already have performed
  // access checks on behalf of the given caller.  But, we can verify this.
  if (VerifyMethodHandles && caller_jh != NULL) {
    klassOop reference_klass = java_lang_Class::as_klassOop(sun_dyn_MemberName::clazz(mname()));
    if (reference_klass != NULL) {
      // Emulate LinkResolver::check_klass_accessability.
      klassOop caller = java_lang_Class::as_klassOop(JNIHandles::resolve_non_null(caller_jh));
      if (!Reflection::verify_class_access(caller,
                                           reference_klass,
                                           true)) {
        THROW_MSG(vmSymbols::java_lang_InternalError(), Klass::cast(reference_klass)->external_name());
      }
    }
  }

  MethodHandles::resolve_MemberName(mname, CHECK);
}
JVM_END

//  static native int getMembers(Class<?> defc, String matchName, String matchSig,
//          int matchFlags, Class<?> caller, int skip, MemberName[] results);
JVM_ENTRY(jint, MHI_getMembers(JNIEnv *env, jobject igcls,
                               jclass clazz_jh, jstring name_jh, jstring sig_jh,
                               int mflags, jclass caller_jh, jint skip, jobjectArray results_jh)) {
  if (clazz_jh == NULL || results_jh == NULL)  return -1;
  klassOop k_oop = java_lang_Class::as_klassOop(JNIHandles::resolve_non_null(clazz_jh));

  objArrayOop results = (objArrayOop) JNIHandles::resolve(results_jh);
  if (results == NULL || !results->is_objArray())       return -1;

  symbolOop name = NULL, sig = NULL;
  if (name_jh != NULL) {
    name = java_lang_String::as_symbol_or_null(JNIHandles::resolve_non_null(name_jh));
    if (name == NULL)  return 0; // a match is not possible
  }
  if (sig_jh != NULL) {
    sig = java_lang_String::as_symbol_or_null(JNIHandles::resolve_non_null(sig_jh));
    if (sig == NULL)  return 0; // a match is not possible
  }

  klassOop caller = NULL;
  if (caller_jh != NULL) {
    oop caller_oop = JNIHandles::resolve_non_null(caller_jh);
    if (!java_lang_Class::is_instance(caller_oop))  return -1;
    caller = java_lang_Class::as_klassOop(caller_oop);
  }

  if (name != NULL && sig != NULL && results != NULL) {
    // try a direct resolve
    // %%% TO DO
  }

  int res = MethodHandles::find_MemberNames(k_oop, name, sig, mflags,
                                            caller, skip, results);
  // TO DO: expand at least some of the MemberNames, to avoid massive callbacks
  return res;
}
JVM_END

JVM_ENTRY(void, MHI_registerBootstrap(JNIEnv *env, jobject igcls, jclass caller_jh, jobject bsm_jh)) {
  instanceKlassHandle ik = MethodHandles::resolve_instance_klass(caller_jh, THREAD);
  if (!AllowTransitionalJSR292) {
    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
              "registerBootstrapMethod is only supported in JSR 292 EDR");
  }
  ik->link_class(CHECK);
  if (!java_dyn_MethodHandle::is_instance(JNIHandles::resolve(bsm_jh))) {
    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "method handle");
  }
  const char* err = NULL;
  if (ik->is_initialized() || ik->is_in_error_state()) {
    err = "too late: class is already initialized";
  } else {
    ObjectLocker ol(ik, THREAD);  // note:  this should be a recursive lock
    if (ik->is_not_initialized() ||
        (ik->is_being_initialized() && ik->is_reentrant_initialization(THREAD))) {
      if (ik->bootstrap_method() != NULL) {
        err = "class is already equipped with a bootstrap method";
      } else {
        ik->set_bootstrap_method(JNIHandles::resolve_non_null(bsm_jh));
        err = NULL;
      }
    } else {
      err = "class is already initialized";
      if (ik->is_being_initialized())
        err = "class is already being initialized in a different thread";
    }
  }
  if (err != NULL) {
    THROW_MSG(vmSymbols::java_lang_IllegalStateException(), err);
  }
}
JVM_END

JVM_ENTRY(jobject, MHI_getBootstrap(JNIEnv *env, jobject igcls, jclass caller_jh)) {
  instanceKlassHandle ik = MethodHandles::resolve_instance_klass(caller_jh, THREAD);
  return JNIHandles::make_local(THREAD, ik->bootstrap_method());
}
JVM_END

JVM_ENTRY(void, MHI_setCallSiteTarget(JNIEnv *env, jobject igcls, jobject site_jh, jobject target_jh)) {
  // No special action required, yet.
  oop site_oop = JNIHandles::resolve(site_jh);
  if (!java_dyn_CallSite::is_instance(site_oop))
    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "not a CallSite");
  java_dyn_CallSite::set_target(site_oop, JNIHandles::resolve(target_jh));
}
JVM_END


/// JVM_RegisterMethodHandleMethods

#define ADR "J"

#define LANG "Ljava/lang/"
#define JDYN "Ljava/dyn/"
#define IDYN "Lsun/dyn/"

#define OBJ   LANG"Object;"
#define CLS   LANG"Class;"
#define STRG  LANG"String;"
#define CST   JDYN"CallSite;"
#define MT    JDYN"MethodType;"
#define MH    JDYN"MethodHandle;"
#define MHI   IDYN"MethodHandleImpl;"
#define MEM   IDYN"MemberName;"
#define AMH   IDYN"AdapterMethodHandle;"
#define BMH   IDYN"BoundMethodHandle;"
#define DMH   IDYN"DirectMethodHandle;"

#define CC (char*)  /*cast a literal from (const char*)*/
#define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)

// These are the native methods on sun.dyn.MethodHandleNatives.
static JNINativeMethod methods[] = {
  // void init(MemberName self, AccessibleObject ref)
  {CC"init",                    CC"("AMH""MH"I)V",              FN_PTR(MHI_init_AMH)},
  {CC"init",                    CC"("BMH""OBJ"I)V",             FN_PTR(MHI_init_BMH)},
  {CC"init",                    CC"("DMH""OBJ"Z"CLS")V",        FN_PTR(MHI_init_DMH)},
  {CC"init",                    CC"("MT")V",                    FN_PTR(MHI_init_MT)},
  {CC"init",                    CC"("MEM""OBJ")V",              FN_PTR(MHI_init_Mem)},
  {CC"expand",                  CC"("MEM")V",                   FN_PTR(MHI_expand_Mem)},
  {CC"resolve",                 CC"("MEM""CLS")V",              FN_PTR(MHI_resolve_Mem)},
  {CC"getTarget",               CC"("MH"I)"OBJ,                 FN_PTR(MHI_getTarget)},
  {CC"getConstant",             CC"(I)I",                       FN_PTR(MHI_getConstant)},
  //  static native int getNamedCon(int which, Object[] name)
  {CC"getNamedCon",             CC"(I["OBJ")I",                 FN_PTR(MHI_getNamedCon)},
  //  static native int getMembers(Class<?> defc, String matchName, String matchSig,
  //          int matchFlags, Class<?> caller, int skip, MemberName[] results);
  {CC"getMembers",              CC"("CLS""STRG""STRG"I"CLS"I["MEM")I",  FN_PTR(MHI_getMembers)}
};

// More entry points specifically for EnableInvokeDynamic.
static JNINativeMethod methods2[] = {
  {CC"registerBootstrap",       CC"("CLS MH")V",                FN_PTR(MHI_registerBootstrap)},
  {CC"getBootstrap",            CC"("CLS")"MH,                  FN_PTR(MHI_getBootstrap)},
  {CC"setCallSiteTarget",       CC"("CST MH")V",                FN_PTR(MHI_setCallSiteTarget)}
};


// This one function is exported, used by NativeLookup.

JVM_ENTRY(void, JVM_RegisterMethodHandleMethods(JNIEnv *env, jclass MHN_class)) {
  assert(MethodHandles::spot_check_entry_names(), "entry enum is OK");

  // note: this explicit warning-producing stuff will be replaced by auto-detection of the JSR 292 classes

  if (!EnableMethodHandles) {
    warning("JSR 292 method handles are disabled in this JVM.  Use -XX:+UnlockExperimentalVMOptions -XX:+EnableMethodHandles to enable.");
    return;  // bind nothing
  }

  bool enable_MH = true;

  {
    ThreadToNativeFromVM ttnfv(thread);

    int status = env->RegisterNatives(MHN_class, methods, sizeof(methods)/sizeof(JNINativeMethod));
    if (env->ExceptionOccurred()) {
      MethodHandles::set_enabled(false);
      warning("JSR 292 method handle code is mismatched to this JVM.  Disabling support.");
      enable_MH = false;
      env->ExceptionClear();
    }
  }

  if (enable_MH) {
    KlassHandle MHI_klass = SystemDictionaryHandles::MethodHandleImpl_klass();
    if (MHI_klass.not_null()) {
      symbolHandle raiseException_name = oopFactory::new_symbol_handle("raiseException", CHECK);
      symbolHandle raiseException_sig  = oopFactory::new_symbol_handle("(ILjava/lang/Object;Ljava/lang/Object;)V", CHECK);
      methodOop raiseException_method  = instanceKlass::cast(MHI_klass->as_klassOop())
                    ->find_method(raiseException_name(), raiseException_sig());
      if (raiseException_method != NULL && raiseException_method->is_static()) {
        MethodHandles::set_raise_exception_method(raiseException_method);
      } else {
        warning("JSR 292 method handle code is mismatched to this JVM.  Disabling support.");
        enable_MH = false;
      }
    }
  }

  if (enable_MH) {
    MethodHandles::set_enabled(true);
  }

  if (!EnableInvokeDynamic) {
    warning("JSR 292 invokedynamic is disabled in this JVM.  Use -XX:+UnlockExperimentalVMOptions -XX:+EnableInvokeDynamic to enable.");
    return;  // bind nothing
  }

  {
    ThreadToNativeFromVM ttnfv(thread);

    int status = env->RegisterNatives(MHN_class, methods2, sizeof(methods2)/sizeof(JNINativeMethod));
    if (env->ExceptionOccurred()) {
      MethodHandles::set_enabled(false);
      warning("JSR 292 method handle code is mismatched to this JVM.  Disabling support.");
      env->ExceptionClear();
    } else {
      MethodHandles::set_enabled(true);
    }
  }
}
JVM_END