/*

 * Copyright (c) 2008, 2011, 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.

 *

 */

#ifndef SHARE_VM_PRIMS_METHODHANDLES_HPP

#define SHARE_VM_PRIMS_METHODHANDLES_HPP

#include "classfile/javaClasses.hpp"

#include "classfile/vmSymbols.hpp"

#include "runtime/frame.inline.hpp"

#include "runtime/globals.hpp"

#include "runtime/interfaceSupport.hpp"

class MacroAssembler;

class Label;

class MethodHandleEntry;

class MethodHandles: AllStatic {

  // JVM support for MethodHandle, MethodType, and related types

  // in java.lang.invoke and sun.invoke.

  // See also  javaClasses for layouts java_lang_invoke_Method{Handle,Type,Type::Form}.

 public:

  enum EntryKind {

    _raise_exception,           // stub for error generation from other stubs

    _invokestatic_mh,           // how a MH emulates invokestatic

    _invokespecial_mh,          // ditto for the other invokes...

    _invokevirtual_mh,

    _invokeinterface_mh,

    _bound_ref_mh,              // reference argument is bound

    _bound_int_mh,              // int argument is bound (via an Integer or Float)

    _bound_long_mh,             // long argument is bound (via a Long or Double)

    _bound_ref_direct_mh,       // same as above, with direct linkage to methodOop

    _bound_int_direct_mh,

    _bound_long_direct_mh,

    _adapter_mh_first,     // adapter sequence goes here...

    _adapter_retype_only   = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_RETYPE_ONLY,

    _adapter_retype_raw    = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_RETYPE_RAW,

    _adapter_check_cast    = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_CHECK_CAST,

    _adapter_prim_to_prim  = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_PRIM_TO_PRIM,

    _adapter_ref_to_prim   = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_REF_TO_PRIM,

    _adapter_prim_to_ref   = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_PRIM_TO_REF,

    _adapter_swap_args     = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_SWAP_ARGS,

    _adapter_rot_args      = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_ROT_ARGS,

    _adapter_dup_args      = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_DUP_ARGS,

    _adapter_drop_args     = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_DROP_ARGS,

    _adapter_collect_args  = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_COLLECT_ARGS,

    _adapter_spread_args   = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_SPREAD_ARGS,

    _adapter_flyby         = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_FLYBY,

    _adapter_ricochet      = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::OP_RICOCHET,

    _adapter_mh_last       = _adapter_mh_first + java_lang_invoke_AdapterMethodHandle::CONV_OP_LIMIT - 1,

    // Optimized adapter types

    // argument list reordering

    _adapter_opt_swap_1,

    _adapter_opt_swap_2,

    _adapter_opt_rot_1_up,

    _adapter_opt_rot_1_down,

    _adapter_opt_rot_2_up,

    _adapter_opt_rot_2_down,

    // primitive single to single:

    _adapter_opt_i2i,           // i2c, i2z, i2b, i2s

    // primitive double to single:

    _adapter_opt_l2i,

    _adapter_opt_d2f,

    // primitive single to double:

    _adapter_opt_i2l,

    _adapter_opt_f2d,

    // conversion between floating point and integer type is handled by Java

    // reference to primitive:

    _adapter_opt_unboxi,

    _adapter_opt_unboxl,

    // spreading (array length cases 0, 1, >=2)

    _adapter_opt_spread_0,

    _adapter_opt_spread_1,

    _adapter_opt_spread_more,

    _EK_LIMIT,

    _EK_FIRST = 0

  };

 public:

  static bool enabled()                         { return _enabled; }

  static void set_enabled(bool z);

 private:

  enum {  // import java_lang_invoke_AdapterMethodHandle::CONV_OP_*

    CONV_OP_LIMIT         = java_lang_invoke_AdapterMethodHandle::CONV_OP_LIMIT,

    CONV_OP_MASK          = java_lang_invoke_AdapterMethodHandle::CONV_OP_MASK,

    CONV_VMINFO_MASK      = java_lang_invoke_AdapterMethodHandle::CONV_VMINFO_MASK,

    CONV_VMINFO_SHIFT     = java_lang_invoke_AdapterMethodHandle::CONV_VMINFO_SHIFT,

    CONV_OP_SHIFT         = java_lang_invoke_AdapterMethodHandle::CONV_OP_SHIFT,

    CONV_DEST_TYPE_SHIFT  = java_lang_invoke_AdapterMethodHandle::CONV_DEST_TYPE_SHIFT,

    CONV_SRC_TYPE_SHIFT   = java_lang_invoke_AdapterMethodHandle::CONV_SRC_TYPE_SHIFT,

    CONV_STACK_MOVE_SHIFT = java_lang_invoke_AdapterMethodHandle::CONV_STACK_MOVE_SHIFT,

    CONV_STACK_MOVE_MASK  = java_lang_invoke_AdapterMethodHandle::CONV_STACK_MOVE_MASK

  };

  static bool _enabled;

  static MethodHandleEntry* _entries[_EK_LIMIT];

  static const char*        _entry_names[_EK_LIMIT+1];

  static jobject            _raise_exception_method;

  // Adapters.

  static MethodHandlesAdapterBlob* _adapter_code;

  static int                       _adapter_code_size;

  static bool ek_valid(EntryKind ek)            { return (uint)ek < (uint)_EK_LIMIT; }

  static bool conv_op_valid(int op)             { return (uint)op < (uint)CONV_OP_LIMIT; }

 public:

  static bool    have_entry(EntryKind ek)       { return ek_valid(ek) && _entries[ek] != NULL; }

  static MethodHandleEntry* entry(EntryKind ek) { assert(ek_valid(ek), "initialized");

                                                  return _entries[ek]; }

  static const char* entry_name(EntryKind ek)   { assert(ek_valid(ek), "oob");

                                                  return _entry_names[ek]; }

  static EntryKind adapter_entry_kind(int op)   { assert(conv_op_valid(op), "oob");

                                                  return EntryKind(_adapter_mh_first + op); }

  static void init_entry(EntryKind ek, MethodHandleEntry* me) {

    assert(ek_valid(ek), "oob");

    assert(_entries[ek] == NULL, "no double initialization");

    _entries[ek] = me;

  }

  // Some adapter helper functions.

  static void get_ek_bound_mh_info(EntryKind ek, BasicType& arg_type, int& arg_mask, int& arg_slots) {

    switch (ek) {

    case _bound_int_mh        : // fall-thru

    case _bound_int_direct_mh : arg_type = T_INT;    arg_mask = _INSERT_INT_MASK;  break;

    case _bound_long_mh       : // fall-thru

    case _bound_long_direct_mh: arg_type = T_LONG;   arg_mask = _INSERT_LONG_MASK; break;

    case _bound_ref_mh        : // fall-thru

    case _bound_ref_direct_mh : arg_type = T_OBJECT; arg_mask = _INSERT_REF_MASK;  break;

    default: ShouldNotReachHere();

    }

    arg_slots = type2size[arg_type];

  }

  static void get_ek_adapter_opt_swap_rot_info(EntryKind ek, int& swap_bytes, int& rotate) {

    int swap_slots = 0;

    switch (ek) {

    case _adapter_opt_swap_1:     swap_slots = 1; rotate =  0; break;

    case _adapter_opt_swap_2:     swap_slots = 2; rotate =  0; break;

    case _adapter_opt_rot_1_up:   swap_slots = 1; rotate =  1; break;

    case _adapter_opt_rot_1_down: swap_slots = 1; rotate = -1; break;

    case _adapter_opt_rot_2_up:   swap_slots = 2; rotate =  1; break;

    case _adapter_opt_rot_2_down: swap_slots = 2; rotate = -1; break;

    default: ShouldNotReachHere();

    }

    // Return the size of the stack slots to move in bytes.

    swap_bytes = swap_slots * Interpreter::stackElementSize;

  }

  static int get_ek_adapter_opt_spread_info(EntryKind ek) {

    switch (ek) {

    case _adapter_opt_spread_0: return  0;

    case _adapter_opt_spread_1: return  1;

    default                   : return -1;

    }

  }

  static methodOop raise_exception_method() {

    oop rem = JNIHandles::resolve(_raise_exception_method);

    assert(rem == NULL || rem->is_method(), "");

    return (methodOop) rem;

  }

  static void set_raise_exception_method(methodOop rem) {

    assert(_raise_exception_method == NULL, "");

    _raise_exception_method = JNIHandles::make_global(Handle(rem));

  }

  static jint adapter_conversion(int conv_op, BasicType src, BasicType dest,

                                 int stack_move = 0, int vminfo = 0) {

    assert(conv_op_valid(conv_op), "oob");

    jint conv = ((conv_op      << CONV_OP_SHIFT)

                 | (src        << CONV_SRC_TYPE_SHIFT)

                 | (dest       << CONV_DEST_TYPE_SHIFT)

                 | (stack_move << CONV_STACK_MOVE_SHIFT)

                 | (vminfo     << CONV_VMINFO_SHIFT)

                 );

    assert(adapter_conversion_op(conv) == conv_op, "decode conv_op");

    assert(adapter_conversion_src_type(conv) == src, "decode src");

    assert(adapter_conversion_dest_type(conv) == dest, "decode dest");

    assert(adapter_conversion_stack_move(conv) == stack_move, "decode stack_move");

    assert(adapter_conversion_vminfo(conv) == vminfo, "decode vminfo");

    return conv;

  }

  static int adapter_conversion_op(jint conv) {

    return ((conv >> CONV_OP_SHIFT) & 0xF);

  }

  static BasicType adapter_conversion_src_type(jint conv) {

    return (BasicType)((conv >> CONV_SRC_TYPE_SHIFT) & 0xF);

  }

  static BasicType adapter_conversion_dest_type(jint conv) {

    return (BasicType)((conv >> CONV_DEST_TYPE_SHIFT) & 0xF);

  }

  static int adapter_conversion_stack_move(jint conv) {

    return (conv >> CONV_STACK_MOVE_SHIFT);

  }

  static int adapter_conversion_vminfo(jint conv) {

    return (conv >> CONV_VMINFO_SHIFT) & CONV_VMINFO_MASK;

  }

  // Bit mask of conversion_op values.  May vary by platform.

  static int adapter_conversion_ops_supported_mask();

  // Offset in words that the interpreter stack pointer moves when an argument is pushed.

  // The stack_move value must always be a multiple of this.

  static int stack_move_unit() {

    return frame::interpreter_frame_expression_stack_direction() * Interpreter::stackElementWords;

  }

  enum { CONV_VMINFO_SIGN_FLAG = 0x80 };

  // Shift values for prim-to-prim conversions.

  static int adapter_prim_to_prim_subword_vminfo(BasicType dest) {

    if (dest == T_BOOLEAN) return (BitsPerInt - 1);  // boolean is 1 bit

    if (dest == T_CHAR)    return (BitsPerInt - BitsPerShort);

    if (dest == T_BYTE)    return (BitsPerInt - BitsPerByte ) | CONV_VMINFO_SIGN_FLAG;

    if (dest == T_SHORT)   return (BitsPerInt - BitsPerShort) | CONV_VMINFO_SIGN_FLAG;

    return 0;                   // case T_INT

  }

  // Shift values for unboxing a primitive.

  static int adapter_unbox_subword_vminfo(BasicType dest) {

    if (dest == T_BOOLEAN) return (BitsPerInt - BitsPerByte );  // implemented as 1 byte

    if (dest == T_CHAR)    return (BitsPerInt - BitsPerShort);

    if (dest == T_BYTE)    return (BitsPerInt - BitsPerByte ) | CONV_VMINFO_SIGN_FLAG;

    if (dest == T_SHORT)   return (BitsPerInt - BitsPerShort) | CONV_VMINFO_SIGN_FLAG;

    return 0;                   // case T_INT

  }

  // Here is the transformation the i2i adapter must perform:

  static int truncate_subword_from_vminfo(jint value, int vminfo) {

    jint tem = value << vminfo;

    if ((vminfo & CONV_VMINFO_SIGN_FLAG) != 0) {

      return (jint)tem >> vminfo;

    } else {

      return (juint)tem >> vminfo;

    }

  }

  static inline address from_compiled_entry(EntryKind ek);

  static inline address from_interpreted_entry(EntryKind ek);

  // helpers for decode_method.

  static methodOop decode_methodOop(methodOop m, int& decode_flags_result);

  static methodOop decode_vmtarget(oop vmtarget, int vmindex, oop mtype, klassOop& receiver_limit_result, int& decode_flags_result);

  static methodOop decode_MemberName(oop mname, klassOop& receiver_limit_result, int& decode_flags_result);

  static methodOop decode_MethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result);

  static methodOop decode_DirectMethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result);

  static methodOop decode_BoundMethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result);

  static methodOop decode_AdapterMethodHandle(oop mh, klassOop& receiver_limit_result, int& decode_flags_result);

  // Find out how many stack slots an mh pushes or pops.

  // The result is *not* reported as a multiple of stack_move_unit();

  // It is a signed net number of pushes (a difference in vmslots).

  // To compare with a stack_move value, first multiply by stack_move_unit().

  static int decode_MethodHandle_stack_pushes(oop mh);

 public:

  // working with member names

  static void resolve_MemberName(Handle mname, TRAPS); // compute vmtarget/vmindex from name/type

  static void expand_MemberName(Handle mname, int suppress, TRAPS);  // expand defc/name/type if missing

  static Handle new_MemberName(TRAPS);  // must be followed by init_MemberName

  static void init_MemberName(oop mname_oop, oop target); // compute vmtarget/vmindex from target

  static void init_MemberName(oop mname_oop, methodOop m, bool do_dispatch = true);

  static void init_MemberName(oop mname_oop, klassOop field_holder, AccessFlags mods, int offset);

  static int find_MemberNames(klassOop k, Symbol* name, Symbol* sig,

                              int mflags, klassOop caller,

                              int skip, objArrayOop results);

  // bit values for suppress argument to expand_MemberName:

  enum { _suppress_defc = 1, _suppress_name = 2, _suppress_type = 4 };

  // Generate MethodHandles adapters.

  static void generate_adapters();

  // Called from InterpreterGenerator and MethodHandlesAdapterGenerator.

  static address generate_method_handle_interpreter_entry(MacroAssembler* _masm);

  static void generate_method_handle_stub(MacroAssembler* _masm, EntryKind ek);

  // argument list parsing

  static int argument_slot(oop method_type, int arg);

  static int argument_slot_count(oop method_type) { return argument_slot(method_type, -1); }

  static int argument_slot_to_argnum(oop method_type, int argslot);

  // Runtime support

  enum {                        // bit-encoded flags from decode_method or decode_vmref

    _dmf_has_receiver   = 0x01, // target method has leading reference argument

    _dmf_does_dispatch  = 0x02, // method handle performs virtual or interface dispatch

    _dmf_from_interface = 0x04, // peforms interface dispatch

    _DMF_DIRECT_MASK    = (_dmf_from_interface*2 - _dmf_has_receiver),

    _dmf_binds_method   = 0x08,

    _dmf_binds_argument = 0x10,

    _DMF_BOUND_MASK     = (_dmf_binds_argument*2 - _dmf_binds_method),

    _dmf_adapter_lsb    = 0x20,

    _DMF_ADAPTER_MASK   = (_dmf_adapter_lsb << CONV_OP_LIMIT) - _dmf_adapter_lsb

  };

  static methodOop decode_method(oop x, klassOop& receiver_limit_result, int& decode_flags_result);

  enum {

    // format of query to getConstant:

    GC_JVM_PUSH_LIMIT = 0,

    GC_JVM_STACK_MOVE_UNIT = 1,

    GC_CONV_OP_IMPLEMENTED_MASK = 2,

    // format of result from getTarget / encode_target:

    ETF_HANDLE_OR_METHOD_NAME = 0, // all available data (immediate MH or method)

    ETF_DIRECT_HANDLE         = 1, // ultimate method handle (will be a DMH, may be self)

    ETF_METHOD_NAME           = 2, // ultimate method as MemberName

    ETF_REFLECT_METHOD        = 3  // ultimate method as java.lang.reflect object (sans refClass)

  };

  static int get_named_constant(int which, Handle name_box, TRAPS);

  static oop encode_target(Handle mh, int format, TRAPS); // report vmtarget (to Java code)

  static bool class_cast_needed(klassOop src, klassOop dst);

  static instanceKlassHandle resolve_instance_klass(oop    java_mirror_oop, TRAPS);

  static instanceKlassHandle resolve_instance_klass(jclass java_mirror_jh,  TRAPS) {

    return resolve_instance_klass(JNIHandles::resolve(java_mirror_jh), THREAD);

  }

 private:

  // These checkers operate on a pair of whole MethodTypes:

  static const char* 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 = false);

  static const char* check_method_type_insertion(oop src_mtype,

                                                 int insert_argnum, oop insert_type,

                                                 oop dst_mtype) {

    oop no_ref = NULL;

    return check_method_type_change(src_mtype, 0, -1,

                                    insert_argnum, insert_type,

                                    -1, no_ref, -1, dst_mtype, 0, -1);

  }

  static const char* check_method_type_conversion(oop src_mtype,

                                                  int change_argnum, oop change_type,

                                                  oop dst_mtype) {

    oop no_ref = NULL;

    return check_method_type_change(src_mtype, 0, -1, -1, no_ref,

                                    change_argnum, change_type,

                                    -1, dst_mtype, 0, -1);

  }

  static const char* check_method_type_passthrough(oop src_mtype, oop dst_mtype, bool raw) {

    oop no_ref = NULL;

    return check_method_type_change(src_mtype, 0, -1,

                                    -1, no_ref, -1, no_ref, -1,

                                    dst_mtype, 0, -1, raw);

  }

  // These checkers operate on pairs of argument or return types:

  static const char* check_argument_type_change(BasicType src_type, klassOop src_klass,

                                                BasicType dst_type, klassOop dst_klass,

                                                int argnum, bool raw = false);

  static const char* check_argument_type_change(oop src_type, oop dst_type,

                                                int argnum, bool raw = false) {

    klassOop src_klass = NULL, dst_klass = NULL;

    BasicType src_bt = java_lang_Class::as_BasicType(src_type, &src_klass);

    BasicType dst_bt = java_lang_Class::as_BasicType(dst_type, &dst_klass);

    return check_argument_type_change(src_bt, src_klass,

                                      dst_bt, dst_klass, argnum, raw);

  }

  static const char* check_return_type_change(oop src_type, oop dst_type, bool raw = false) {

    return check_argument_type_change(src_type, dst_type, -1, raw);

  }

  static const char* check_return_type_change(BasicType src_type, klassOop src_klass,

                                              BasicType dst_type, klassOop dst_klass) {

    return check_argument_type_change(src_type, src_klass, dst_type, dst_klass, -1);

  }

  static const char* check_method_receiver(methodOop m, klassOop passed_recv_type);

  // These verifiers can block, and will throw an error if the checking fails:

  static void verify_vmslots(Handle mh, TRAPS);

  static void verify_vmargslot(Handle mh, int argnum, int argslot, TRAPS);

  static void verify_method_type(methodHandle m, Handle mtype,

                                 bool has_bound_oop,

                                 KlassHandle bound_oop_type,

                                 TRAPS);

  static void verify_method_signature(methodHandle m, Handle mtype,

                                      int first_ptype_pos,

                                      KlassHandle insert_ptype, TRAPS);

  static void verify_DirectMethodHandle(Handle mh, methodHandle m, TRAPS);

  static void verify_BoundMethodHandle(Handle mh, Handle target, int argnum,

                                       bool direct_to_method, TRAPS);

  static void verify_BoundMethodHandle_with_receiver(Handle mh, methodHandle m, TRAPS);

  static void verify_AdapterMethodHandle(Handle mh, int argnum, TRAPS);

 public:

  // Fill in the fields of a DirectMethodHandle mh.  (MH.type must be pre-filled.)

  static void init_DirectMethodHandle(Handle mh, methodHandle method, bool do_dispatch, TRAPS);

  // Fill in the fields of a BoundMethodHandle mh.  (MH.type, BMH.argument must be pre-filled.)

  static void init_BoundMethodHandle(Handle mh, Handle target, int argnum, TRAPS);

  static void init_BoundMethodHandle_with_receiver(Handle mh,

                                                   methodHandle original_m,

                                                   KlassHandle receiver_limit,

                                                   int decode_flags,

                                                   TRAPS);

  // Fill in the fields of an AdapterMethodHandle mh.  (MH.type must be pre-filled.)

  static void init_AdapterMethodHandle(Handle mh, Handle target, int argnum, TRAPS);

#ifdef ASSERT

  static bool spot_check_entry_names();

#endif

 private:

  static methodHandle dispatch_decoded_method(methodHandle m,

                                              KlassHandle receiver_limit,

                                              int decode_flags,

                                              KlassHandle receiver_klass,

                                              TRAPS);

  static bool same_basic_type_for_arguments(BasicType src, BasicType dst,

                                            bool raw = false,

                                            bool for_return = false);

  static bool same_basic_type_for_returns(BasicType src, BasicType dst, bool raw = false) {

    return same_basic_type_for_arguments(src, dst, raw, true);

  }

  enum {                        // arg_mask values

    _INSERT_NO_MASK   = -1,

    _INSERT_REF_MASK  = 0,

    _INSERT_INT_MASK  = 1,

    _INSERT_LONG_MASK = 3

  };

  static void insert_arg_slots(MacroAssembler* _masm,

                               RegisterOrConstant arg_slots,

                               int arg_mask,

                               Register argslot_reg,

                               Register temp_reg, Register temp2_reg, Register temp3_reg = noreg);

  static void remove_arg_slots(MacroAssembler* _masm,

                               RegisterOrConstant arg_slots,

                               Register argslot_reg,

                               Register temp_reg, Register temp2_reg, Register temp3_reg = noreg);

  static void trace_method_handle(MacroAssembler* _masm, const char* adaptername) PRODUCT_RETURN;

  static Symbol* convert_to_signature(oop type_str, bool polymorphic, TRAPS);

};

// Access methods for the "entry" field of a java.lang.invoke.MethodHandle.

// The field is primarily a jump target for compiled calls.

// However, we squirrel away some nice pointers for other uses,

// just before the jump target.

// Aspects of a method handle entry:

//  - from_compiled_entry - stub used when compiled code calls the MH

//  - from_interpreted_entry - stub used when the interpreter calls the MH

//  - type_checking_entry - stub for runtime casting between MHForm siblings (NYI)

class MethodHandleEntry {

 public:

  class Data {

    friend class MethodHandleEntry;

    size_t              _total_size; // size including Data and code stub

    MethodHandleEntry*  _type_checking_entry;

    address             _from_interpreted_entry;

    MethodHandleEntry* method_entry() { return (MethodHandleEntry*)(this + 1); }

  };

  Data*     data()                              { return (Data*)this - 1; }

  address   start_address()                     { return (address) data(); }

  address   end_address()                       { return start_address() + data()->_total_size; }

  address   from_compiled_entry()               { return (address) this; }

  address   from_interpreted_entry()            { return data()->_from_interpreted_entry; }

  void  set_from_interpreted_entry(address e)   { data()->_from_interpreted_entry = e; }

  MethodHandleEntry* type_checking_entry()           { return data()->_type_checking_entry; }

  void set_type_checking_entry(MethodHandleEntry* e) { data()->_type_checking_entry = e; }

  void set_end_address(address end_addr) {

    size_t total_size = end_addr - start_address();

    assert(total_size > 0 && total_size < 0x1000, "reasonable end address");

    data()->_total_size = total_size;

  }

  // Compiler support:

  static int from_interpreted_entry_offset_in_bytes() {

    return (int)( offset_of(Data, _from_interpreted_entry) - sizeof(Data) );

  }