1 /*
   2  * Copyright (c) 2008, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "interpreter/interpreter.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/oopFactory.hpp"
  30 #include "prims/methodHandles.hpp"
  31 #include "runtime/javaCalls.hpp"
  32 #include "runtime/reflection.hpp"
  33 #include "runtime/signature.hpp"
  34 #include "runtime/stubRoutines.hpp"
  35 
  36 /*
  37  * JSR 292 reference implementation: method handles
  38  */
  39 
  40 bool MethodHandles::_enabled = false; // set true after successful native linkage
  41 
  42 MethodHandleEntry* MethodHandles::_entries[MethodHandles::_EK_LIMIT] = {NULL};
  43 const char*        MethodHandles::_entry_names[_EK_LIMIT+1] = {
  44   "raise_exception",
  45   "invokestatic",               // how a MH emulates invokestatic
  46   "invokespecial",              // ditto for the other invokes...
  47   "invokevirtual",
  48   "invokeinterface",
  49   "bound_ref",                  // these are for BMH...
  50   "bound_int",
  51   "bound_long",
  52   "bound_ref_direct",           // (direct versions have a direct methodOop)
  53   "bound_int_direct",
  54   "bound_long_direct",
  55 
  56   // starting at _adapter_mh_first:
  57   "adapter_retype_only",       // these are for AMH...
  58   "adapter_retype_raw",
  59   "adapter_check_cast",
  60   "adapter_prim_to_prim",
  61   "adapter_ref_to_prim",
  62   "adapter_prim_to_ref",
  63   "adapter_swap_args",
  64   "adapter_rot_args",
  65   "adapter_dup_args",
  66   "adapter_drop_args",
  67   "adapter_collect_args",
  68   "adapter_spread_args",
  69   "adapter_fold_args",
  70   "adapter_unused_13",
  71 
  72   // optimized adapter types:
  73   "adapter_swap_args/1",
  74   "adapter_swap_args/2",
  75   "adapter_rot_args/1,up",
  76   "adapter_rot_args/1,down",
  77   "adapter_rot_args/2,up",
  78   "adapter_rot_args/2,down",
  79   "adapter_prim_to_prim/i2i",
  80   "adapter_prim_to_prim/l2i",
  81   "adapter_prim_to_prim/d2f",
  82   "adapter_prim_to_prim/i2l",
  83   "adapter_prim_to_prim/f2d",
  84   "adapter_ref_to_prim/unboxi",
  85   "adapter_ref_to_prim/unboxl",
  86 
  87   // return value handlers for collect/filter/fold adapters:
  88   "return/ref",
  89   "return/int",
  90   "return/long",
  91   "return/float",
  92   "return/double",
  93   "return/void",
  94   "return/S0/ref",
  95   "return/S1/ref",
  96   "return/S2/ref",
  97   "return/S3/ref",
  98   "return/S4/ref",
  99   "return/S5/ref",
 100   "return/any",
 101 
 102   // spreading (array length cases 0, 1, ...)
 103   "adapter_spread/0",
 104   "adapter_spread/1/ref",
 105   "adapter_spread/2/ref",
 106   "adapter_spread/3/ref",
 107   "adapter_spread/4/ref",
 108   "adapter_spread/5/ref",
 109   "adapter_spread/ref",
 110   "adapter_spread/byte",
 111   "adapter_spread/char",
 112   "adapter_spread/short",
 113   "adapter_spread/int",
 114   "adapter_spread/long",
 115   "adapter_spread/float",
 116   "adapter_spread/double",
 117 
 118   // blocking filter/collect conversions:
 119   "adapter_collect/ref",
 120   "adapter_collect/int",
 121   "adapter_collect/long",
 122   "adapter_collect/float",
 123   "adapter_collect/double",
 124   "adapter_collect/void",
 125   "adapter_collect/0/ref",
 126   "adapter_collect/1/ref",
 127   "adapter_collect/2/ref",
 128   "adapter_collect/3/ref",
 129   "adapter_collect/4/ref",
 130   "adapter_collect/5/ref",
 131   "adapter_filter/S0/ref",
 132   "adapter_filter/S1/ref",
 133   "adapter_filter/S2/ref",
 134   "adapter_filter/S3/ref",
 135   "adapter_filter/S4/ref",
 136   "adapter_filter/S5/ref",
 137   "adapter_collect/2/S0/ref",
 138   "adapter_collect/2/S1/ref",
 139   "adapter_collect/2/S2/ref",
 140   "adapter_collect/2/S3/ref",
 141   "adapter_collect/2/S4/ref",
 142   "adapter_collect/2/S5/ref",
 143 
 144   // blocking fold conversions:
 145   "adapter_fold/ref",
 146   "adapter_fold/int",
 147   "adapter_fold/long",
 148   "adapter_fold/float",
 149   "adapter_fold/double",
 150   "adapter_fold/void",
 151   "adapter_fold/1/ref",
 152   "adapter_fold/2/ref",
 153   "adapter_fold/3/ref",
 154   "adapter_fold/4/ref",
 155   "adapter_fold/5/ref",
 156 
 157   NULL
 158 };
 159 
 160 // Adapters.
 161 MethodHandlesAdapterBlob* MethodHandles::_adapter_code      = NULL;
 162 int                       MethodHandles::_adapter_code_size = StubRoutines::method_handles_adapters_code_size;
 163 
 164 jobject MethodHandles::_raise_exception_method;
 165 
 166 address MethodHandles::_adapter_return_handlers[CONV_TYPE_MASK+1];
 167 
 168 #ifdef ASSERT
 169 bool MethodHandles::spot_check_entry_names() {
 170   assert(!strcmp(entry_name(_invokestatic_mh), "invokestatic"), "");
 171   assert(!strcmp(entry_name(_bound_ref_mh), "bound_ref"), "");
 172   assert(!strcmp(entry_name(_adapter_retype_only), "adapter_retype_only"), "");
 173   assert(!strcmp(entry_name(_adapter_fold_args), "adapter_fold_args"), "");
 174   assert(!strcmp(entry_name(_adapter_opt_unboxi), "adapter_ref_to_prim/unboxi"), "");
 175   assert(!strcmp(entry_name(_adapter_opt_spread_char), "adapter_spread/char"), "");
 176   assert(!strcmp(entry_name(_adapter_opt_spread_double), "adapter_spread/double"), "");
 177   assert(!strcmp(entry_name(_adapter_opt_collect_int), "adapter_collect/int"), "");
 178   assert(!strcmp(entry_name(_adapter_opt_collect_0_ref), "adapter_collect/0/ref"), "");
 179   assert(!strcmp(entry_name(_adapter_opt_collect_2_S3_ref), "adapter_collect/2/S3/ref"), "");
 180   assert(!strcmp(entry_name(_adapter_opt_filter_S5_ref), "adapter_filter/S5/ref"), "");
 181   assert(!strcmp(entry_name(_adapter_opt_fold_3_ref), "adapter_fold/3/ref"), "");
 182   assert(!strcmp(entry_name(_adapter_opt_fold_void), "adapter_fold/void"), "");
 183   return true;
 184 }
 185 #endif
 186 
 187 
 188 //------------------------------------------------------------------------------
 189 // MethodHandles::generate_adapters
 190 //
 191 void MethodHandles::generate_adapters() {
 192 #ifdef TARGET_ARCH_NYI_6939861
 193   if (FLAG_IS_DEFAULT(UseRicochetFrames))  UseRicochetFrames = false;
 194 #endif
 195   if (!EnableInvokeDynamic || SystemDictionary::MethodHandle_klass() == NULL)  return;
 196 
 197   assert(_adapter_code == NULL, "generate only once");
 198 
 199   ResourceMark rm;
 200   TraceTime timer("MethodHandles adapters generation", TraceStartupTime);
 201   _adapter_code = MethodHandlesAdapterBlob::create(_adapter_code_size);
 202   if (_adapter_code == NULL)
 203     vm_exit_out_of_memory(_adapter_code_size, "CodeCache: no room for MethodHandles adapters");
 204   CodeBuffer code(_adapter_code);
 205   MethodHandlesAdapterGenerator g(&code);
 206   g.generate();
 207 }
 208 
 209 //------------------------------------------------------------------------------
 210 // MethodHandlesAdapterGenerator::generate
 211 //
 212 void MethodHandlesAdapterGenerator::generate() {
 213   // Generate generic method handle adapters.
 214   for (MethodHandles::EntryKind ek = MethodHandles::_EK_FIRST;
 215        ek < MethodHandles::_EK_LIMIT;
 216        ek = MethodHandles::EntryKind(1 + (int)ek)) {
 217     if (MethodHandles::ek_supported(ek)) {
 218       StubCodeMark mark(this, "MethodHandle", MethodHandles::entry_name(ek));
 219       MethodHandles::generate_method_handle_stub(_masm, ek);
 220     }
 221   }
 222 }
 223 
 224 
 225 #ifdef TARGET_ARCH_NYI_6939861
 226 // these defs belong in methodHandles_<arch>.cpp
 227 frame MethodHandles::ricochet_frame_sender(const frame& fr, RegisterMap *map) {
 228   ShouldNotCallThis();
 229   return fr;
 230 }
 231 void MethodHandles::ricochet_frame_oops_do(const frame& fr, OopClosure* f, const RegisterMap* reg_map) {
 232   ShouldNotCallThis();
 233 }
 234 #endif //TARGET_ARCH_NYI_6939861
 235 
 236 
 237 //------------------------------------------------------------------------------
 238 // MethodHandles::ek_supported
 239 //
 240 bool MethodHandles::ek_supported(MethodHandles::EntryKind ek) {
 241   MethodHandles::EntryKind ek_orig = MethodHandles::ek_original_kind(ek);
 242   switch (ek_orig) {
 243   case _adapter_unused_13:
 244     return false;  // not defined yet
 245   case _adapter_prim_to_ref:
 246     return UseRicochetFrames && conv_op_supported(java_lang_invoke_AdapterMethodHandle::OP_PRIM_TO_REF);
 247   case _adapter_collect_args:
 248     return UseRicochetFrames && conv_op_supported(java_lang_invoke_AdapterMethodHandle::OP_COLLECT_ARGS);
 249   case _adapter_fold_args:
 250     return UseRicochetFrames && conv_op_supported(java_lang_invoke_AdapterMethodHandle::OP_FOLD_ARGS);
 251   case _adapter_opt_return_any:
 252     return UseRicochetFrames;
 253 #ifdef TARGET_ARCH_NYI_6939861
 254   // ports before 6939861 supported only three kinds of spread ops
 255   case _adapter_spread_args:
 256     // restrict spreads to three kinds:
 257     switch (ek) {
 258     case _adapter_opt_spread_0:
 259     case _adapter_opt_spread_1:
 260     case _adapter_opt_spread_more:
 261       break;
 262     default:
 263       return false;
 264       break;
 265     }
 266     break;
 267 #endif //TARGET_ARCH_NYI_6939861
 268   }
 269   return true;
 270 }
 271 
 272 
 273 void MethodHandles::set_enabled(bool z) {
 274   if (_enabled != z) {
 275     guarantee(z && EnableInvokeDynamic, "can only enable once, and only if -XX:+EnableInvokeDynamic");
 276     _enabled = z;
 277   }
 278 }
 279 
 280 // Note: A method which does not have a TRAPS argument cannot block in the GC
 281 // or throw exceptions.  Such methods are used in this file to do something quick
 282 // and local, like parse a data structure.  For speed, such methods work on plain
 283 // oops, not handles.  Trapping methods uniformly operate on handles.
 284 
 285 methodHandle MethodHandles::decode_vmtarget(oop vmtarget, int vmindex, oop mtype,
 286                                             KlassHandle& receiver_limit_result, int& decode_flags_result) {
 287   if (vmtarget == NULL)  return methodHandle();
 288   assert(methodOopDesc::nonvirtual_vtable_index < 0, "encoding");
 289   if (vmindex < 0) {
 290     // this DMH performs no dispatch; it is directly bound to a methodOop
 291     // A MemberName may either be directly bound to a methodOop,
 292     // or it may use the klass/index form; both forms mean the same thing.
 293     methodOop m = decode_methodOop(methodOop(vmtarget), decode_flags_result);
 294     if ((decode_flags_result & _dmf_has_receiver) != 0
 295         && java_lang_invoke_MethodType::is_instance(mtype)) {
 296       // Extract receiver type restriction from mtype.ptypes[0].
 297       objArrayOop ptypes = java_lang_invoke_MethodType::ptypes(mtype);
 298       oop ptype0 = (ptypes == NULL || ptypes->length() < 1) ? oop(NULL) : ptypes->obj_at(0);
 299       if (java_lang_Class::is_instance(ptype0))
 300         receiver_limit_result = java_lang_Class::as_klassOop(ptype0);
 301     }
 302     if (vmindex == methodOopDesc::nonvirtual_vtable_index) {
 303       // this DMH can be an "invokespecial" version
 304       decode_flags_result &= ~_dmf_does_dispatch;
 305     } else {
 306       assert(vmindex == methodOopDesc::invalid_vtable_index, "random vmindex?");
 307     }
 308     return m;
 309   } else {
 310     assert(vmtarget->is_klass(), "must be class or interface");
 311     decode_flags_result |= MethodHandles::_dmf_does_dispatch;
 312     decode_flags_result |= MethodHandles::_dmf_has_receiver;
 313     receiver_limit_result = (klassOop)vmtarget;
 314     Klass* tk = Klass::cast((klassOop)vmtarget);
 315     if (tk->is_interface()) {
 316       // an itable linkage is <interface, itable index>
 317       decode_flags_result |= MethodHandles::_dmf_from_interface;
 318       return klassItable::method_for_itable_index((klassOop)vmtarget, vmindex);
 319     } else {
 320       if (!tk->oop_is_instance())
 321         tk = instanceKlass::cast(SystemDictionary::Object_klass());
 322       return ((instanceKlass*)tk)->method_at_vtable(vmindex);
 323     }
 324   }
 325 }
 326 
 327 // MemberName and DirectMethodHandle have the same linkage to the JVM internals.
 328 // (MemberName is the non-operational name used for queries and setup.)
 329 
 330 methodHandle MethodHandles::decode_DirectMethodHandle(oop mh, KlassHandle& receiver_limit_result, int& decode_flags_result) {
 331   oop vmtarget = java_lang_invoke_DirectMethodHandle::vmtarget(mh);
 332   int vmindex  = java_lang_invoke_DirectMethodHandle::vmindex(mh);
 333   oop mtype    = java_lang_invoke_DirectMethodHandle::type(mh);
 334   return decode_vmtarget(vmtarget, vmindex, mtype, receiver_limit_result, decode_flags_result);
 335 }
 336 
 337 methodHandle MethodHandles::decode_BoundMethodHandle(oop mh, KlassHandle& receiver_limit_result, int& decode_flags_result) {
 338   assert(java_lang_invoke_BoundMethodHandle::is_instance(mh), "");
 339   assert(mh->klass() != SystemDictionary::AdapterMethodHandle_klass(), "");
 340   for (oop bmh = mh;;) {
 341     // Bound MHs can be stacked to bind several arguments.
 342     oop target = java_lang_invoke_MethodHandle::vmtarget(bmh);
 343     if (target == NULL)  return methodHandle();
 344     decode_flags_result |= MethodHandles::_dmf_binds_argument;
 345     klassOop tk = target->klass();
 346     if (tk == SystemDictionary::BoundMethodHandle_klass()) {
 347       bmh = target;
 348       continue;
 349     } else {
 350       if (java_lang_invoke_MethodHandle::is_subclass(tk)) {
 351         //assert(tk == SystemDictionary::DirectMethodHandle_klass(), "end of BMH chain must be DMH");
 352         return decode_MethodHandle(target, receiver_limit_result, decode_flags_result);
 353       } else {
 354         // Optimized case:  binding a receiver to a non-dispatched DMH
 355         // short-circuits directly to the methodOop.
 356         // (It might be another argument besides a receiver also.)
 357         assert(target->is_method(), "must be a simple method");
 358         decode_flags_result |= MethodHandles::_dmf_binds_method;
 359         methodOop m = (methodOop) target;
 360         if (!m->is_static())
 361           decode_flags_result |= MethodHandles::_dmf_has_receiver;
 362         return m;
 363       }
 364     }
 365   }
 366 }
 367 
 368 methodHandle MethodHandles::decode_AdapterMethodHandle(oop mh, KlassHandle& receiver_limit_result, int& decode_flags_result) {
 369   assert(mh->klass() == SystemDictionary::AdapterMethodHandle_klass(), "");
 370   for (oop amh = mh;;) {
 371     // Adapter MHs can be stacked to convert several arguments.
 372     int conv_op = adapter_conversion_op(java_lang_invoke_AdapterMethodHandle::conversion(amh));
 373     decode_flags_result |= (_dmf_adapter_lsb << conv_op) & _DMF_ADAPTER_MASK;
 374     oop target = java_lang_invoke_MethodHandle::vmtarget(amh);
 375     if (target == NULL)  return methodHandle();
 376     klassOop tk = target->klass();
 377     if (tk == SystemDictionary::AdapterMethodHandle_klass()) {
 378       amh = target;
 379       continue;
 380     } else {
 381       // must be a BMH (which will bind some more arguments) or a DMH (for the final call)
 382       return MethodHandles::decode_MethodHandle(target, receiver_limit_result, decode_flags_result);
 383     }
 384   }
 385 }
 386 
 387 methodHandle MethodHandles::decode_MethodHandle(oop mh, KlassHandle& receiver_limit_result, int& decode_flags_result) {
 388   if (mh == NULL)  return methodHandle();
 389   klassOop mhk = mh->klass();
 390   assert(java_lang_invoke_MethodHandle::is_subclass(mhk), "must be a MethodHandle");
 391   if (mhk == SystemDictionary::DirectMethodHandle_klass()) {
 392     return decode_DirectMethodHandle(mh, receiver_limit_result, decode_flags_result);
 393   } else if (mhk == SystemDictionary::BoundMethodHandle_klass()) {
 394     return decode_BoundMethodHandle(mh, receiver_limit_result, decode_flags_result);
 395   } else if (mhk == SystemDictionary::AdapterMethodHandle_klass()) {
 396     return decode_AdapterMethodHandle(mh, receiver_limit_result, decode_flags_result);
 397   } else if (java_lang_invoke_BoundMethodHandle::is_subclass(mhk)) {
 398     // could be a JavaMethodHandle (but not an adapter MH)
 399     return decode_BoundMethodHandle(mh, receiver_limit_result, decode_flags_result);
 400   } else {
 401     assert(false, "cannot parse this MH");
 402     return methodHandle();  // random MH?
 403   }
 404 }
 405 
 406 methodOop MethodHandles::decode_methodOop(methodOop m, int& decode_flags_result) {
 407   assert(m->is_method(), "");
 408   if (m->is_static()) {
 409     // check that signature begins '(L' or '([' (not '(I', '()', etc.)
 410     Symbol* sig = m->signature();
 411     BasicType recv_bt = char2type(sig->byte_at(1));
 412     // Note: recv_bt might be T_ILLEGAL if byte_at(2) is ')'
 413     assert(sig->byte_at(0) == '(', "must be method sig");
 414 //     if (recv_bt == T_OBJECT || recv_bt == T_ARRAY)
 415 //       decode_flags_result |= _dmf_has_receiver;
 416   } else {
 417     // non-static method
 418     decode_flags_result |= _dmf_has_receiver;
 419     if (!m->can_be_statically_bound() && !m->is_initializer()) {
 420       decode_flags_result |= _dmf_does_dispatch;
 421       if (Klass::cast(m->method_holder())->is_interface())
 422         decode_flags_result |= _dmf_from_interface;
 423     }
 424   }
 425   return m;
 426 }
 427 
 428 
 429 // A trusted party is handing us a cookie to determine a method.
 430 // Let's boil it down to the method oop they really want.
 431 methodHandle MethodHandles::decode_method(oop x, KlassHandle& receiver_limit_result, int& decode_flags_result) {
 432   decode_flags_result = 0;
 433   receiver_limit_result = KlassHandle();
 434   klassOop xk = x->klass();
 435   if (xk == Universe::methodKlassObj()) {
 436     return decode_methodOop((methodOop) x, decode_flags_result);
 437   } else if (xk == SystemDictionary::MemberName_klass()) {
 438     // Note: This only works if the MemberName has already been resolved.
 439     return decode_MemberName(x, receiver_limit_result, decode_flags_result);
 440   } else if (java_lang_invoke_MethodHandle::is_subclass(xk)) {
 441     return decode_MethodHandle(x, receiver_limit_result, decode_flags_result);
 442   } else if (xk == SystemDictionary::reflect_Method_klass()) {
 443     oop clazz  = java_lang_reflect_Method::clazz(x);
 444     int slot   = java_lang_reflect_Method::slot(x);
 445     klassOop k = java_lang_Class::as_klassOop(clazz);
 446     if (k != NULL && Klass::cast(k)->oop_is_instance())
 447       return decode_methodOop(instanceKlass::cast(k)->method_with_idnum(slot),
 448                               decode_flags_result);
 449   } else if (xk == SystemDictionary::reflect_Constructor_klass()) {
 450     oop clazz  = java_lang_reflect_Constructor::clazz(x);
 451     int slot   = java_lang_reflect_Constructor::slot(x);
 452     klassOop k = java_lang_Class::as_klassOop(clazz);
 453     if (k != NULL && Klass::cast(k)->oop_is_instance())
 454       return decode_methodOop(instanceKlass::cast(k)->method_with_idnum(slot),
 455                               decode_flags_result);
 456   } else {
 457     // unrecognized object
 458     assert(!x->is_method(), "already checked");
 459     assert(!java_lang_invoke_MemberName::is_instance(x), "already checked");
 460   }
 461   return methodHandle();
 462 }
 463 
 464 
 465 int MethodHandles::decode_MethodHandle_stack_pushes(oop mh) {
 466   if (mh->klass() == SystemDictionary::DirectMethodHandle_klass())
 467     return 0;                   // no push/pop
 468   int this_vmslots = java_lang_invoke_MethodHandle::vmslots(mh);
 469   int last_vmslots = 0;
 470   oop last_mh = mh;
 471   for (;;) {
 472     oop target = java_lang_invoke_MethodHandle::vmtarget(last_mh);
 473     if (target->klass() == SystemDictionary::DirectMethodHandle_klass()) {
 474       last_vmslots = java_lang_invoke_MethodHandle::vmslots(target);
 475       break;
 476     } else if (!java_lang_invoke_MethodHandle::is_instance(target)) {
 477       // might be klass or method
 478       assert(target->is_method(), "must get here with a direct ref to method");
 479       last_vmslots = methodOop(target)->size_of_parameters();
 480       break;
 481     }
 482     last_mh = target;
 483   }
 484   // If I am called with fewer VM slots than my ultimate callee,
 485   // it must be that I push the additionally needed slots.
 486   // Likewise if am called with more VM slots, I will pop them.
 487   return (last_vmslots - this_vmslots);
 488 }
 489 
 490 
 491 // MemberName support
 492 
 493 // import java_lang_invoke_MemberName.*
 494 enum {
 495   IS_METHOD      = java_lang_invoke_MemberName::MN_IS_METHOD,
 496   IS_CONSTRUCTOR = java_lang_invoke_MemberName::MN_IS_CONSTRUCTOR,
 497   IS_FIELD       = java_lang_invoke_MemberName::MN_IS_FIELD,
 498   IS_TYPE        = java_lang_invoke_MemberName::MN_IS_TYPE,
 499   SEARCH_SUPERCLASSES = java_lang_invoke_MemberName::MN_SEARCH_SUPERCLASSES,
 500   SEARCH_INTERFACES   = java_lang_invoke_MemberName::MN_SEARCH_INTERFACES,
 501   ALL_KINDS      = IS_METHOD | IS_CONSTRUCTOR | IS_FIELD | IS_TYPE,
 502   VM_INDEX_UNINITIALIZED = java_lang_invoke_MemberName::VM_INDEX_UNINITIALIZED
 503 };
 504 
 505 Handle MethodHandles::new_MemberName(TRAPS) {
 506   Handle empty;
 507   instanceKlassHandle k(THREAD, SystemDictionary::MemberName_klass());
 508   if (!k->is_initialized())  k->initialize(CHECK_(empty));
 509   return Handle(THREAD, k->allocate_instance(THREAD));
 510 }
 511 
 512 void MethodHandles::init_MemberName(oop mname_oop, oop target_oop) {
 513   if (target_oop->klass() == SystemDictionary::reflect_Field_klass()) {
 514     oop clazz = java_lang_reflect_Field::clazz(target_oop); // fd.field_holder()
 515     int slot  = java_lang_reflect_Field::slot(target_oop);  // fd.index()
 516     int mods  = java_lang_reflect_Field::modifiers(target_oop);
 517     klassOop k = java_lang_Class::as_klassOop(clazz);
 518     int offset = instanceKlass::cast(k)->offset_from_fields(slot);
 519     init_MemberName(mname_oop, k, accessFlags_from(mods), offset);
 520   } else {
 521     KlassHandle receiver_limit; int decode_flags = 0;
 522     methodHandle m = MethodHandles::decode_method(target_oop, receiver_limit, decode_flags);
 523     bool do_dispatch = ((decode_flags & MethodHandles::_dmf_does_dispatch) != 0);
 524     init_MemberName(mname_oop, m(), do_dispatch);
 525   }
 526 }
 527 
 528 void MethodHandles::init_MemberName(oop mname_oop, methodOop m, bool do_dispatch) {
 529   int flags = ((m->is_initializer() ? IS_CONSTRUCTOR : IS_METHOD)
 530                | (jushort)( m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS ));
 531   oop vmtarget = m;
 532   int vmindex  = methodOopDesc::invalid_vtable_index;  // implies no info yet
 533   if (!do_dispatch || (flags & IS_CONSTRUCTOR) || m->can_be_statically_bound())
 534     vmindex = methodOopDesc::nonvirtual_vtable_index; // implies never any dispatch
 535   assert(vmindex != VM_INDEX_UNINITIALIZED, "Java sentinel value");
 536   java_lang_invoke_MemberName::set_vmtarget(mname_oop, vmtarget);
 537   java_lang_invoke_MemberName::set_vmindex(mname_oop,  vmindex);
 538   java_lang_invoke_MemberName::set_flags(mname_oop,    flags);
 539   java_lang_invoke_MemberName::set_clazz(mname_oop,    Klass::cast(m->method_holder())->java_mirror());
 540 }
 541 
 542 void MethodHandles::init_MemberName(oop mname_oop, klassOop field_holder, AccessFlags mods, int offset) {
 543   int flags = (IS_FIELD | (jushort)( mods.as_short() & JVM_RECOGNIZED_FIELD_MODIFIERS ));
 544   oop vmtarget = field_holder;
 545   int vmindex  = offset;  // determines the field uniquely when combined with static bit
 546   assert(vmindex != VM_INDEX_UNINITIALIZED, "bad alias on vmindex");
 547   java_lang_invoke_MemberName::set_vmtarget(mname_oop, vmtarget);
 548   java_lang_invoke_MemberName::set_vmindex(mname_oop,  vmindex);
 549   java_lang_invoke_MemberName::set_flags(mname_oop,    flags);
 550   java_lang_invoke_MemberName::set_clazz(mname_oop,    Klass::cast(field_holder)->java_mirror());
 551 }
 552 
 553 
 554 methodHandle MethodHandles::decode_MemberName(oop mname, KlassHandle& receiver_limit_result, int& decode_flags_result) {
 555   methodHandle empty;
 556   int flags  = java_lang_invoke_MemberName::flags(mname);
 557   if ((flags & (IS_METHOD | IS_CONSTRUCTOR)) == 0)  return empty;  // not invocable
 558   oop vmtarget = java_lang_invoke_MemberName::vmtarget(mname);
 559   int vmindex  = java_lang_invoke_MemberName::vmindex(mname);
 560   if (vmindex == VM_INDEX_UNINITIALIZED)  return empty;  // not resolved
 561   methodHandle m = decode_vmtarget(vmtarget, vmindex, NULL, receiver_limit_result, decode_flags_result);
 562   oop clazz = java_lang_invoke_MemberName::clazz(mname);
 563   if (clazz != NULL && java_lang_Class::is_instance(clazz)) {
 564     klassOop klass = java_lang_Class::as_klassOop(clazz);
 565     if (klass != NULL)  receiver_limit_result = klass;
 566   }
 567   return m;
 568 }
 569 
 570 // convert the external string or reflective type to an internal signature
 571 Symbol* MethodHandles::convert_to_signature(oop type_str, bool polymorphic, TRAPS) {
 572   if (java_lang_invoke_MethodType::is_instance(type_str)) {
 573     return java_lang_invoke_MethodType::as_signature(type_str, polymorphic, CHECK_NULL);
 574   } else if (java_lang_Class::is_instance(type_str)) {
 575     return java_lang_Class::as_signature(type_str, false, CHECK_NULL);
 576   } else if (java_lang_String::is_instance(type_str)) {
 577     if (polymorphic) {
 578       return java_lang_String::as_symbol(type_str, CHECK_NULL);
 579     } else {
 580       return java_lang_String::as_symbol_or_null(type_str);
 581     }
 582   } else {
 583     THROW_MSG_(vmSymbols::java_lang_InternalError(), "unrecognized type", NULL);
 584   }
 585 }
 586 
 587 // An unresolved member name is a mere symbolic reference.
 588 // Resolving it plants a vmtarget/vmindex in it,
 589 // which refers dirctly to JVM internals.
 590 void MethodHandles::resolve_MemberName(Handle mname, TRAPS) {
 591   assert(java_lang_invoke_MemberName::is_instance(mname()), "");
 592 #ifdef ASSERT
 593   // If this assert throws, renegotiate the sentinel value used by the Java code,
 594   // so that it is distinct from any valid vtable index value, and any special
 595   // values defined in methodOopDesc::VtableIndexFlag.
 596   // The point of the slop is to give the Java code and the JVM some room
 597   // to independently specify sentinel values.
 598   const int sentinel_slop  = 10;
 599   const int sentinel_limit = methodOopDesc::highest_unused_vtable_index_value - sentinel_slop;
 600   assert(VM_INDEX_UNINITIALIZED < sentinel_limit, "Java sentinel != JVM sentinels");
 601 #endif
 602   if (java_lang_invoke_MemberName::vmindex(mname()) != VM_INDEX_UNINITIALIZED)
 603     return;  // already resolved
 604   Handle defc_oop(THREAD, java_lang_invoke_MemberName::clazz(mname()));
 605   Handle name_str(THREAD, java_lang_invoke_MemberName::name( mname()));
 606   Handle type_str(THREAD, java_lang_invoke_MemberName::type( mname()));
 607   int    flags    =       java_lang_invoke_MemberName::flags(mname());
 608 
 609   if (defc_oop.is_null() || name_str.is_null() || type_str.is_null()) {
 610     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "nothing to resolve");
 611   }
 612 
 613   instanceKlassHandle defc;
 614   {
 615     klassOop defc_klassOop = java_lang_Class::as_klassOop(defc_oop());
 616     if (defc_klassOop == NULL)  return;  // a primitive; no resolution possible
 617     if (!Klass::cast(defc_klassOop)->oop_is_instance()) {
 618       if (!Klass::cast(defc_klassOop)->oop_is_array())  return;
 619       defc_klassOop = SystemDictionary::Object_klass();
 620     }
 621     defc = instanceKlassHandle(THREAD, defc_klassOop);
 622   }
 623   if (defc.is_null()) {
 624     THROW_MSG(vmSymbols::java_lang_InternalError(), "primitive class");
 625   }
 626   defc->link_class(CHECK);  // possible safepoint
 627 
 628   // convert the external string name to an internal symbol
 629   TempNewSymbol name = java_lang_String::as_symbol_or_null(name_str());
 630   if (name == NULL)  return;  // no such name
 631 
 632   Handle polymorphic_method_type;
 633   bool polymorphic_signature = false;
 634   if ((flags & ALL_KINDS) == IS_METHOD &&
 635       (defc() == SystemDictionary::MethodHandle_klass() &&
 636        methodOopDesc::is_method_handle_invoke_name(name))) {
 637     polymorphic_signature = true;
 638   }
 639 
 640   // convert the external string or reflective type to an internal signature
 641   TempNewSymbol type = convert_to_signature(type_str(), polymorphic_signature, CHECK);
 642   if (java_lang_invoke_MethodType::is_instance(type_str()) && polymorphic_signature) {
 643     polymorphic_method_type = type_str;  // preserve exactly
 644   }
 645   if (type == NULL)  return;  // no such signature exists in the VM
 646 
 647   // Time to do the lookup.
 648   switch (flags & ALL_KINDS) {
 649   case IS_METHOD:
 650     {
 651       CallInfo result;
 652       {
 653         EXCEPTION_MARK;
 654         if ((flags & JVM_ACC_STATIC) != 0) {
 655           LinkResolver::resolve_static_call(result,
 656                         defc, name, type, KlassHandle(), false, false, THREAD);
 657         } else if (defc->is_interface()) {
 658           LinkResolver::resolve_interface_call(result, Handle(), defc,
 659                         defc, name, type, KlassHandle(), false, false, THREAD);
 660         } else {
 661           LinkResolver::resolve_virtual_call(result, Handle(), defc,
 662                         defc, name, type, KlassHandle(), false, false, THREAD);
 663         }
 664         if (HAS_PENDING_EXCEPTION) {
 665           CLEAR_PENDING_EXCEPTION;
 666           break;  // go to second chance
 667         }
 668       }
 669       methodHandle m = result.resolved_method();
 670       oop vmtarget = NULL;
 671       int vmindex = methodOopDesc::nonvirtual_vtable_index;
 672       if (defc->is_interface()) {
 673         vmindex = klassItable::compute_itable_index(m());
 674         assert(vmindex >= 0, "");
 675       } else if (result.has_vtable_index()) {
 676         vmindex = result.vtable_index();
 677         assert(vmindex >= 0, "");
 678       }
 679       assert(vmindex != VM_INDEX_UNINITIALIZED, "");
 680       if (vmindex < 0) {
 681         assert(result.is_statically_bound(), "");
 682         vmtarget = m();
 683       } else {
 684         vmtarget = result.resolved_klass()->as_klassOop();
 685       }
 686       int mods = (m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS);
 687       java_lang_invoke_MemberName::set_vmtarget(mname(), vmtarget);
 688       java_lang_invoke_MemberName::set_vmindex(mname(),  vmindex);
 689       java_lang_invoke_MemberName::set_modifiers(mname(), mods);
 690       DEBUG_ONLY(KlassHandle junk1; int junk2);
 691       assert(decode_MemberName(mname(), junk1, junk2) == result.resolved_method(),
 692              "properly stored for later decoding");
 693       return;
 694     }
 695   case IS_CONSTRUCTOR:
 696     {
 697       CallInfo result;
 698       {
 699         EXCEPTION_MARK;
 700         if (name == vmSymbols::object_initializer_name()) {
 701           LinkResolver::resolve_special_call(result,
 702                         defc, name, type, KlassHandle(), false, THREAD);
 703         } else {
 704           break;                // will throw after end of switch
 705         }
 706         if (HAS_PENDING_EXCEPTION) {
 707           CLEAR_PENDING_EXCEPTION;
 708           return;
 709         }
 710       }
 711       assert(result.is_statically_bound(), "");
 712       methodHandle m = result.resolved_method();
 713       oop vmtarget = m();
 714       int vmindex  = methodOopDesc::nonvirtual_vtable_index;
 715       int mods     = (m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS);
 716       java_lang_invoke_MemberName::set_vmtarget(mname(), vmtarget);
 717       java_lang_invoke_MemberName::set_vmindex(mname(),  vmindex);
 718       java_lang_invoke_MemberName::set_modifiers(mname(), mods);
 719       DEBUG_ONLY(KlassHandle junk1; int junk2);
 720       assert(decode_MemberName(mname(), junk1, junk2) == result.resolved_method(),
 721              "properly stored for later decoding");
 722       return;
 723     }
 724   case IS_FIELD:
 725     {
 726       // This is taken from LinkResolver::resolve_field, sans access checks.
 727       fieldDescriptor fd; // find_field initializes fd if found
 728       KlassHandle sel_klass(THREAD, instanceKlass::cast(defc())->find_field(name, type, &fd));
 729       // check if field exists; i.e., if a klass containing the field def has been selected
 730       if (sel_klass.is_null())  return;
 731       oop vmtarget = sel_klass->as_klassOop();
 732       int vmindex  = fd.offset();
 733       int mods     = (fd.access_flags().as_short() & JVM_RECOGNIZED_FIELD_MODIFIERS);
 734       if (vmindex == VM_INDEX_UNINITIALIZED)  break;  // should not happen
 735       java_lang_invoke_MemberName::set_vmtarget(mname(),  vmtarget);
 736       java_lang_invoke_MemberName::set_vmindex(mname(),   vmindex);
 737       java_lang_invoke_MemberName::set_modifiers(mname(), mods);
 738       return;
 739     }
 740   default:
 741     THROW_MSG(vmSymbols::java_lang_InternalError(), "unrecognized MemberName format");
 742   }
 743 
 744   // Second chance.
 745   if (polymorphic_method_type.not_null()) {
 746     // Look on a non-null class loader.
 747     Handle cur_class_loader;
 748     const int nptypes = java_lang_invoke_MethodType::ptype_count(polymorphic_method_type());
 749     for (int i = 0; i <= nptypes; i++) {
 750       oop type_mirror;
 751       if (i < nptypes)  type_mirror = java_lang_invoke_MethodType::ptype(polymorphic_method_type(), i);
 752       else              type_mirror = java_lang_invoke_MethodType::rtype(polymorphic_method_type());
 753       klassOop example_type = java_lang_Class::as_klassOop(type_mirror);
 754       if (example_type == NULL)  continue;
 755       oop class_loader = Klass::cast(example_type)->class_loader();
 756       if (class_loader == NULL || class_loader == cur_class_loader())  continue;
 757       cur_class_loader = Handle(THREAD, class_loader);
 758       methodOop m = SystemDictionary::find_method_handle_invoke(name,
 759                                                                 type,
 760                                                                 KlassHandle(THREAD, example_type),
 761                                                                 THREAD);
 762       if (HAS_PENDING_EXCEPTION) {
 763         CLEAR_PENDING_EXCEPTION;
 764         m = NULL;
 765         // try again with a different class loader...
 766       }
 767       if (m != NULL) {
 768         int mods = (m->access_flags().as_short() & JVM_RECOGNIZED_METHOD_MODIFIERS);
 769         java_lang_invoke_MemberName::set_vmtarget(mname(),  m);
 770         java_lang_invoke_MemberName::set_vmindex(mname(),   m->vtable_index());
 771         java_lang_invoke_MemberName::set_modifiers(mname(), mods);
 772         return;
 773       }
 774     }
 775   }
 776 }
 777 
 778 // Conversely, a member name which is only initialized from JVM internals
 779 // may have null defc, name, and type fields.
 780 // Resolving it plants a vmtarget/vmindex in it,
 781 // which refers directly to JVM internals.
 782 void MethodHandles::expand_MemberName(Handle mname, int suppress, TRAPS) {
 783   assert(java_lang_invoke_MemberName::is_instance(mname()), "");
 784   oop vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
 785   int vmindex  = java_lang_invoke_MemberName::vmindex(mname());
 786   if (vmtarget == NULL || vmindex == VM_INDEX_UNINITIALIZED) {
 787     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "nothing to expand");
 788   }
 789 
 790   bool have_defc = (java_lang_invoke_MemberName::clazz(mname()) != NULL);
 791   bool have_name = (java_lang_invoke_MemberName::name(mname()) != NULL);
 792   bool have_type = (java_lang_invoke_MemberName::type(mname()) != NULL);
 793   int flags      = java_lang_invoke_MemberName::flags(mname());
 794 
 795   if (suppress != 0) {
 796     if (suppress & _suppress_defc)  have_defc = true;
 797     if (suppress & _suppress_name)  have_name = true;
 798     if (suppress & _suppress_type)  have_type = true;
 799   }
 800 
 801   if (have_defc && have_name && have_type)  return;  // nothing needed
 802 
 803   switch (flags & ALL_KINDS) {
 804   case IS_METHOD:
 805   case IS_CONSTRUCTOR:
 806     {
 807       KlassHandle receiver_limit; int decode_flags = 0;
 808       methodHandle m = decode_vmtarget(vmtarget, vmindex, NULL, receiver_limit, decode_flags);
 809       if (m.is_null())  break;
 810       if (!have_defc) {
 811         klassOop defc = m->method_holder();
 812         if (receiver_limit.not_null() && receiver_limit() != defc
 813             && Klass::cast(receiver_limit())->is_subtype_of(defc))
 814           defc = receiver_limit();
 815         java_lang_invoke_MemberName::set_clazz(mname(), Klass::cast(defc)->java_mirror());
 816       }
 817       if (!have_name) {
 818         //not java_lang_String::create_from_symbol; let's intern member names
 819         Handle name = StringTable::intern(m->name(), CHECK);
 820         java_lang_invoke_MemberName::set_name(mname(), name());
 821       }
 822       if (!have_type) {
 823         Handle type = java_lang_String::create_from_symbol(m->signature(), CHECK);
 824         java_lang_invoke_MemberName::set_type(mname(), type());
 825       }
 826       return;
 827     }
 828   case IS_FIELD:
 829     {
 830       // This is taken from LinkResolver::resolve_field, sans access checks.
 831       if (!vmtarget->is_klass())  break;
 832       if (!Klass::cast((klassOop) vmtarget)->oop_is_instance())  break;
 833       instanceKlassHandle defc(THREAD, (klassOop) vmtarget);
 834       bool is_static = ((flags & JVM_ACC_STATIC) != 0);
 835       fieldDescriptor fd; // find_field initializes fd if found
 836       if (!defc->find_field_from_offset(vmindex, is_static, &fd))
 837         break;                  // cannot expand
 838       if (!have_defc) {
 839         java_lang_invoke_MemberName::set_clazz(mname(), defc->java_mirror());
 840       }
 841       if (!have_name) {
 842         //not java_lang_String::create_from_symbol; let's intern member names
 843         Handle name = StringTable::intern(fd.name(), CHECK);
 844         java_lang_invoke_MemberName::set_name(mname(), name());
 845       }
 846       if (!have_type) {
 847         Handle type = java_lang_String::create_from_symbol(fd.signature(), CHECK);
 848         java_lang_invoke_MemberName::set_type(mname(), type());
 849       }
 850       return;
 851     }
 852   }
 853   THROW_MSG(vmSymbols::java_lang_InternalError(), "unrecognized MemberName format");
 854 }
 855 
 856 int MethodHandles::find_MemberNames(klassOop k,
 857                                     Symbol* name, Symbol* sig,
 858                                     int mflags, klassOop caller,
 859                                     int skip, objArrayOop results) {
 860   DEBUG_ONLY(No_Safepoint_Verifier nsv);
 861   // this code contains no safepoints!
 862 
 863   // %%% take caller into account!
 864 
 865   if (k == NULL || !Klass::cast(k)->oop_is_instance())  return -1;
 866 
 867   int rfill = 0, rlimit = results->length(), rskip = skip;
 868   // overflow measurement:
 869   int overflow = 0, overflow_limit = MAX2(1000, rlimit);
 870 
 871   int match_flags = mflags;
 872   bool search_superc = ((match_flags & SEARCH_SUPERCLASSES) != 0);
 873   bool search_intfc  = ((match_flags & SEARCH_INTERFACES)   != 0);
 874   bool local_only = !(search_superc | search_intfc);
 875   bool classes_only = false;
 876 
 877   if (name != NULL) {
 878     if (name->utf8_length() == 0)  return 0; // a match is not possible
 879   }
 880   if (sig != NULL) {
 881     if (sig->utf8_length() == 0)  return 0; // a match is not possible
 882     if (sig->byte_at(0) == '(')
 883       match_flags &= ~(IS_FIELD | IS_TYPE);
 884     else
 885       match_flags &= ~(IS_CONSTRUCTOR | IS_METHOD);
 886   }
 887 
 888   if ((match_flags & IS_TYPE) != 0) {
 889     // NYI, and Core Reflection works quite well for this query
 890   }
 891 
 892   if ((match_flags & IS_FIELD) != 0) {
 893     for (FieldStream st(k, local_only, !search_intfc); !st.eos(); st.next()) {
 894       if (name != NULL && st.name() != name)
 895           continue;
 896       if (sig != NULL && st.signature() != sig)
 897         continue;
 898       // passed the filters
 899       if (rskip > 0) {
 900         --rskip;
 901       } else if (rfill < rlimit) {
 902         oop result = results->obj_at(rfill++);
 903         if (!java_lang_invoke_MemberName::is_instance(result))
 904           return -99;  // caller bug!
 905         MethodHandles::init_MemberName(result, st.klass()->as_klassOop(), st.access_flags(), st.offset());
 906       } else if (++overflow >= overflow_limit) {
 907         match_flags = 0; break; // got tired of looking at overflow
 908       }
 909     }
 910   }
 911 
 912   if ((match_flags & (IS_METHOD | IS_CONSTRUCTOR)) != 0) {
 913     // watch out for these guys:
 914     Symbol* init_name   = vmSymbols::object_initializer_name();
 915     Symbol* clinit_name = vmSymbols::class_initializer_name();
 916     if (name == clinit_name)  clinit_name = NULL; // hack for exposing <clinit>
 917     bool negate_name_test = false;
 918     // fix name so that it captures the intention of IS_CONSTRUCTOR
 919     if (!(match_flags & IS_METHOD)) {
 920       // constructors only
 921       if (name == NULL) {
 922         name = init_name;
 923       } else if (name != init_name) {
 924         return 0;               // no constructors of this method name
 925       }
 926     } else if (!(match_flags & IS_CONSTRUCTOR)) {
 927       // methods only
 928       if (name == NULL) {
 929         name = init_name;
 930         negate_name_test = true; // if we see the name, we *omit* the entry
 931       } else if (name == init_name) {
 932         return 0;               // no methods of this constructor name
 933       }
 934     } else {
 935       // caller will accept either sort; no need to adjust name
 936     }
 937     for (MethodStream st(k, local_only, !search_intfc); !st.eos(); st.next()) {
 938       methodOop m = st.method();
 939       Symbol* m_name = m->name();
 940       if (m_name == clinit_name)
 941         continue;
 942       if (name != NULL && ((m_name != name) ^ negate_name_test))
 943           continue;
 944       if (sig != NULL && m->signature() != sig)
 945         continue;
 946       // passed the filters
 947       if (rskip > 0) {
 948         --rskip;
 949       } else if (rfill < rlimit) {
 950         oop result = results->obj_at(rfill++);
 951         if (!java_lang_invoke_MemberName::is_instance(result))
 952           return -99;  // caller bug!
 953         MethodHandles::init_MemberName(result, m, true);
 954       } else if (++overflow >= overflow_limit) {
 955         match_flags = 0; break; // got tired of looking at overflow
 956       }
 957     }
 958   }
 959 
 960   // return number of elements we at leasted wanted to initialize
 961   return rfill + overflow;
 962 }
 963 
 964 
 965 // Decode this java.lang.Class object into an instanceKlass, if possible.
 966 // Throw IAE if not
 967 instanceKlassHandle MethodHandles::resolve_instance_klass(oop java_mirror_oop, TRAPS) {
 968   instanceKlassHandle empty;
 969   klassOop caller = NULL;
 970   if (java_lang_Class::is_instance(java_mirror_oop)) {
 971     caller = java_lang_Class::as_klassOop(java_mirror_oop);
 972   }
 973   if (caller == NULL || !Klass::cast(caller)->oop_is_instance()) {
 974     THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), "not a class", empty);
 975   }
 976   return instanceKlassHandle(THREAD, caller);
 977 }
 978 
 979 
 980 
 981 // Decode the vmtarget field of a method handle.
 982 // Sanitize out methodOops, klassOops, and any other non-Java data.
 983 // This is for debugging and reflection.
 984 oop MethodHandles::encode_target(Handle mh, int format, TRAPS) {
 985   assert(java_lang_invoke_MethodHandle::is_instance(mh()), "must be a MH");
 986   if (format == ETF_HANDLE_OR_METHOD_NAME) {
 987     oop target = java_lang_invoke_MethodHandle::vmtarget(mh());
 988     if (target == NULL) {
 989       return NULL;                // unformed MH
 990     }
 991     klassOop tklass = target->klass();
 992     if (Klass::cast(tklass)->is_subclass_of(SystemDictionary::Object_klass())) {
 993       return target;              // target is another MH (or something else?)
 994     }
 995   }
 996   if (format == ETF_DIRECT_HANDLE) {
 997     oop target = mh();
 998     for (;;) {
 999       if (target->klass() == SystemDictionary::DirectMethodHandle_klass()) {
1000         return target;
1001       }
1002       if (!java_lang_invoke_MethodHandle::is_instance(target)){
1003         return NULL;                // unformed MH
1004       }
1005       target = java_lang_invoke_MethodHandle::vmtarget(target);
1006     }
1007   }
1008   // cases of metadata in MH.vmtarget:
1009   // - AMH can have methodOop for static invoke with bound receiver
1010   // - DMH can have methodOop for static invoke (on variable receiver)
1011   // - DMH can have klassOop for dispatched (non-static) invoke
1012   KlassHandle receiver_limit; int decode_flags = 0;
1013   methodHandle m = decode_MethodHandle(mh(), receiver_limit, decode_flags);
1014   if (m.is_null())  return NULL;
1015   switch (format) {
1016   case ETF_REFLECT_METHOD:
1017     // same as jni_ToReflectedMethod:
1018     if (m->is_initializer()) {
1019       return Reflection::new_constructor(m, THREAD);
1020     } else {
1021       return Reflection::new_method(m, UseNewReflection, false, THREAD);
1022     }
1023 
1024   case ETF_HANDLE_OR_METHOD_NAME:   // method, not handle
1025   case ETF_METHOD_NAME:
1026     {
1027       if (SystemDictionary::MemberName_klass() == NULL)  break;
1028       instanceKlassHandle mname_klass(THREAD, SystemDictionary::MemberName_klass());
1029       mname_klass->initialize(CHECK_NULL);
1030       Handle mname = mname_klass->allocate_instance_handle(CHECK_NULL);  // possible safepoint
1031       java_lang_invoke_MemberName::set_vmindex(mname(), VM_INDEX_UNINITIALIZED);
1032       bool do_dispatch = ((decode_flags & MethodHandles::_dmf_does_dispatch) != 0);
1033       init_MemberName(mname(), m(), do_dispatch);
1034       expand_MemberName(mname, 0, CHECK_NULL);
1035       return mname();
1036     }
1037   }
1038 
1039   // Unknown format code.
1040   char msg[50];
1041   jio_snprintf(msg, sizeof(msg), "unknown getTarget format=%d", format);
1042   THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), msg);
1043 }
1044 
1045 static const char* always_null_names[] = {
1046   "java/lang/Void",
1047   "java/lang/Null",
1048   //"java/lang/Nothing",
1049   "sun/dyn/empty/Empty",
1050   "sun/invoke/empty/Empty",
1051   NULL
1052 };
1053 
1054 static bool is_always_null_type(klassOop klass) {
1055   if (klass == NULL)  return false;  // safety
1056   if (!Klass::cast(klass)->oop_is_instance())  return false;
1057   instanceKlass* ik = instanceKlass::cast(klass);
1058   // Must be on the boot class path:
1059   if (ik->class_loader() != NULL)  return false;
1060   // Check the name.
1061   Symbol* name = ik->name();
1062   for (int i = 0; ; i++) {
1063     const char* test_name = always_null_names[i];
1064     if (test_name == NULL)  break;
1065     if (name->equals(test_name))
1066       return true;
1067   }
1068   return false;
1069 }
1070 
1071 bool MethodHandles::class_cast_needed(klassOop src, klassOop dst) {
1072   if (dst == NULL)  return true;
1073   if (src == NULL)  return (dst != SystemDictionary::Object_klass());
1074   if (src == dst || dst == SystemDictionary::Object_klass())
1075     return false;                               // quickest checks
1076   Klass* srck = Klass::cast(src);
1077   Klass* dstk = Klass::cast(dst);
1078   if (dstk->is_interface()) {
1079     // interface receivers can safely be viewed as untyped,
1080     // because interface calls always include a dynamic check
1081     //dstk = Klass::cast(SystemDictionary::Object_klass());
1082     return false;
1083   }
1084   if (srck->is_interface()) {
1085     // interface arguments must be viewed as untyped
1086     //srck = Klass::cast(SystemDictionary::Object_klass());
1087     return true;
1088   }
1089   if (is_always_null_type(src)) {
1090     // some source types are known to be never instantiated;
1091     // they represent references which are always null
1092     // such null references never fail to convert safely
1093     return false;
1094   }
1095   return !srck->is_subclass_of(dstk->as_klassOop());
1096 }
1097 
1098 static oop object_java_mirror() {
1099   return Klass::cast(SystemDictionary::Object_klass())->java_mirror();
1100 }
1101 
1102 bool MethodHandles::same_basic_type_for_arguments(BasicType src,
1103                                                   BasicType dst,
1104                                                   bool raw,
1105                                                   bool for_return) {
1106   if (for_return) {
1107     // return values can always be forgotten:
1108     if (dst == T_VOID)  return true;
1109     if (src == T_VOID)  return raw && (dst == T_INT);
1110     // We allow caller to receive a garbage int, which is harmless.
1111     // This trick is pulled by trusted code (see VerifyType.canPassRaw).
1112   }
1113   assert(src != T_VOID && dst != T_VOID, "should not be here");
1114   if (src == dst)  return true;
1115   if (type2size[src] != type2size[dst])  return false;
1116   if (src == T_OBJECT || dst == T_OBJECT)  return false;
1117   if (raw)  return true;  // bitwise reinterpretation; caller guarantees safety
1118   // allow reinterpretation casts for integral widening
1119   if (is_subword_type(src)) { // subwords can fit in int or other subwords
1120     if (dst == T_INT)         // any subword fits in an int
1121       return true;
1122     if (src == T_BOOLEAN)     // boolean fits in any subword
1123       return is_subword_type(dst);
1124     if (src == T_BYTE && dst == T_SHORT)
1125       return true;            // remaining case: byte fits in short
1126   }
1127   // allow float/fixed reinterpretation casts
1128   if (src == T_FLOAT)   return dst == T_INT;
1129   if (src == T_INT)     return dst == T_FLOAT;
1130   if (src == T_DOUBLE)  return dst == T_LONG;
1131   if (src == T_LONG)    return dst == T_DOUBLE;
1132   return false;
1133 }
1134 
1135 const char* MethodHandles::check_method_receiver(methodOop m,
1136                                                  klassOop passed_recv_type) {
1137   assert(!m->is_static(), "caller resp.");
1138   if (passed_recv_type == NULL)
1139     return "receiver type is primitive";
1140   if (class_cast_needed(passed_recv_type, m->method_holder())) {
1141     Klass* formal = Klass::cast(m->method_holder());
1142     return SharedRuntime::generate_class_cast_message("receiver type",
1143                                                       formal->external_name());
1144   }
1145   return NULL;                  // checks passed
1146 }
1147 
1148 // Verify that m's signature can be called type-safely by a method handle
1149 // of the given method type 'mtype'.
1150 // It takes a TRAPS argument because it must perform symbol lookups.
1151 void MethodHandles::verify_method_signature(methodHandle m,
1152                                             Handle mtype,
1153                                             int first_ptype_pos,
1154                                             KlassHandle insert_ptype,
1155                                             TRAPS) {
1156   Handle mhi_type;
1157   if (m->is_method_handle_invoke()) {
1158     // use this more exact typing instead of the symbolic signature:
1159     mhi_type = Handle(THREAD, m->method_handle_type());
1160   }
1161   objArrayHandle ptypes(THREAD, java_lang_invoke_MethodType::ptypes(mtype()));
1162   int pnum = first_ptype_pos;
1163   int pmax = ptypes->length();
1164   int anum = 0;                 // method argument
1165   const char* err = NULL;
1166   ResourceMark rm(THREAD);
1167   for (SignatureStream ss(m->signature()); !ss.is_done(); ss.next()) {
1168     oop ptype_oop = NULL;
1169     if (ss.at_return_type()) {
1170       if (pnum != pmax)
1171         { err = "too many arguments"; break; }
1172       ptype_oop = java_lang_invoke_MethodType::rtype(mtype());
1173     } else {
1174       if (pnum >= pmax)
1175         { err = "not enough arguments"; break; }
1176       if (pnum >= 0)
1177         ptype_oop = ptypes->obj_at(pnum);
1178       else if (insert_ptype.is_null())
1179         ptype_oop = NULL;
1180       else
1181         ptype_oop = insert_ptype->java_mirror();
1182       pnum += 1;
1183       anum += 1;
1184     }
1185     KlassHandle pklass;
1186     BasicType   ptype = T_OBJECT;
1187     bool   have_ptype = false;
1188     // missing ptype_oop does not match any non-reference; use Object to report the error
1189     pklass = SystemDictionaryHandles::Object_klass();
1190     if (ptype_oop != NULL) {
1191       have_ptype = true;
1192       klassOop pklass_oop = NULL;
1193       ptype = java_lang_Class::as_BasicType(ptype_oop, &pklass_oop);
1194       pklass = KlassHandle(THREAD, pklass_oop);
1195     }
1196     ptype_oop = NULL; //done with this
1197     KlassHandle aklass;
1198     BasicType   atype = ss.type();
1199     if (atype == T_ARRAY)  atype = T_OBJECT; // fold all refs to T_OBJECT
1200     if (atype == T_OBJECT) {
1201       if (!have_ptype) {
1202         // null matches any reference
1203         continue;
1204       }
1205       if (mhi_type.is_null()) {
1206         // If we fail to resolve types at this point, we will usually throw an error.
1207         TempNewSymbol name = ss.as_symbol_or_null();
1208         if (name != NULL) {
1209           instanceKlass* mk = instanceKlass::cast(m->method_holder());
1210           Handle loader(THREAD, mk->class_loader());
1211           Handle domain(THREAD, mk->protection_domain());
1212           klassOop aklass_oop = SystemDictionary::resolve_or_null(name, loader, domain, CHECK);
1213           if (aklass_oop != NULL)
1214             aklass = KlassHandle(THREAD, aklass_oop);
1215         }
1216       } else {
1217         // for method handle invokers we don't look at the name in the signature
1218         oop atype_oop;
1219         if (ss.at_return_type())
1220           atype_oop = java_lang_invoke_MethodType::rtype(mhi_type());
1221         else
1222           atype_oop = java_lang_invoke_MethodType::ptype(mhi_type(), anum-1);
1223         klassOop aklass_oop = NULL;
1224         atype = java_lang_Class::as_BasicType(atype_oop, &aklass_oop);
1225         aklass = KlassHandle(THREAD, aklass_oop);
1226       }
1227     }
1228     if (!ss.at_return_type()) {
1229       err = check_argument_type_change(ptype, pklass(), atype, aklass(), anum);
1230     } else {
1231       err = check_return_type_change(atype, aklass(), ptype, pklass()); // note reversal!
1232     }
1233     if (err != NULL)  break;
1234   }
1235 
1236   if (err != NULL) {
1237 #ifndef PRODUCT
1238     if (PrintMiscellaneous && (Verbose || WizardMode)) {
1239       tty->print("*** verify_method_signature failed: ");
1240       java_lang_invoke_MethodType::print_signature(mtype(), tty);
1241       tty->cr();
1242       tty->print_cr("    first_ptype_pos = %d, insert_ptype = "UINTX_FORMAT, first_ptype_pos, insert_ptype());
1243       tty->print("    Failing method: ");
1244       m->print();
1245     }
1246 #endif //PRODUCT
1247     THROW_MSG(vmSymbols::java_lang_InternalError(), err);
1248   }
1249 }
1250 
1251 // Main routine for verifying the MethodHandle.type of a proposed
1252 // direct or bound-direct method handle.
1253 void MethodHandles::verify_method_type(methodHandle m,
1254                                        Handle mtype,
1255                                        bool has_bound_recv,
1256                                        KlassHandle bound_recv_type,
1257                                        TRAPS) {
1258   bool m_needs_receiver = !m->is_static();
1259 
1260   const char* err = NULL;
1261 
1262   int first_ptype_pos = m_needs_receiver ? 1 : 0;
1263   if (has_bound_recv) {
1264     first_ptype_pos -= 1;  // ptypes do not include the bound argument; start earlier in them
1265     if (m_needs_receiver && bound_recv_type.is_null())
1266       { err = "bound receiver is not an object"; goto die; }
1267   }
1268 
1269   if (m_needs_receiver && err == NULL) {
1270     objArrayOop ptypes = java_lang_invoke_MethodType::ptypes(mtype());
1271     if (ptypes->length() < first_ptype_pos)
1272       { err = "receiver argument is missing"; goto die; }
1273     if (has_bound_recv)
1274       err = check_method_receiver(m(), bound_recv_type->as_klassOop());
1275     else
1276       err = check_method_receiver(m(), java_lang_Class::as_klassOop(ptypes->obj_at(first_ptype_pos-1)));
1277     if (err != NULL)  goto die;
1278   }
1279 
1280   // Check the other arguments for mistypes.
1281   verify_method_signature(m, mtype, first_ptype_pos, bound_recv_type, CHECK);
1282   return;
1283 
1284  die:
1285   THROW_MSG(vmSymbols::java_lang_InternalError(), err);
1286 }
1287 
1288 void MethodHandles::verify_vmslots(Handle mh, TRAPS) {
1289   // Verify vmslots.
1290   int check_slots = argument_slot_count(java_lang_invoke_MethodHandle::type(mh()));
1291   if (java_lang_invoke_MethodHandle::vmslots(mh()) != check_slots) {
1292     THROW_MSG(vmSymbols::java_lang_InternalError(), "bad vmslots in BMH");
1293   }
1294 }
1295 
1296 void MethodHandles::verify_vmargslot(Handle mh, int argnum, int argslot, TRAPS) {
1297   // Verify that argslot points at the given argnum.
1298   int check_slot = argument_slot(java_lang_invoke_MethodHandle::type(mh()), argnum);
1299   if (argslot != check_slot || argslot < 0) {
1300     const char* fmt = "for argnum of %d, vmargslot is %d, should be %d";
1301     size_t msglen = strlen(fmt) + 3*11 + 1;
1302     char* msg = NEW_RESOURCE_ARRAY(char, msglen);
1303     jio_snprintf(msg, msglen, fmt, argnum, argslot, check_slot);
1304     THROW_MSG(vmSymbols::java_lang_InternalError(), msg);
1305   }
1306 }
1307 
1308 // Verify the correspondence between two method types.
1309 // Apart from the advertised changes, caller method type X must
1310 // be able to invoke the callee method Y type with no violations
1311 // of type integrity.
1312 // Return NULL if all is well, else a short error message.
1313 const char* MethodHandles::check_method_type_change(oop src_mtype, int src_beg, int src_end,
1314                                                     int insert_argnum, oop insert_type,
1315                                                     int change_argnum, oop change_type,
1316                                                     int delete_argnum,
1317                                                     oop dst_mtype, int dst_beg, int dst_end,
1318                                                     bool raw) {
1319   objArrayOop src_ptypes = java_lang_invoke_MethodType::ptypes(src_mtype);
1320   objArrayOop dst_ptypes = java_lang_invoke_MethodType::ptypes(dst_mtype);
1321 
1322   int src_max = src_ptypes->length();
1323   int dst_max = dst_ptypes->length();
1324 
1325   if (src_end == -1)  src_end = src_max;
1326   if (dst_end == -1)  dst_end = dst_max;
1327 
1328   assert(0 <= src_beg && src_beg <= src_end && src_end <= src_max, "oob");
1329   assert(0 <= dst_beg && dst_beg <= dst_end && dst_end <= dst_max, "oob");
1330 
1331   // pending actions; set to -1 when done:
1332   int ins_idx = insert_argnum, chg_idx = change_argnum, del_idx = delete_argnum;
1333 
1334   const char* err = NULL;
1335 
1336   // Walk along each array of parameter types, including a virtual
1337   // NULL end marker at the end of each.
1338   for (int src_idx = src_beg, dst_idx = dst_beg;
1339        (src_idx <= src_end && dst_idx <= dst_end);
1340        src_idx++, dst_idx++) {
1341     oop src_type = (src_idx == src_end) ? oop(NULL) : src_ptypes->obj_at(src_idx);
1342     oop dst_type = (dst_idx == dst_end) ? oop(NULL) : dst_ptypes->obj_at(dst_idx);
1343     bool fix_null_src_type = false;
1344 
1345     // Perform requested edits.
1346     if (ins_idx == src_idx) {
1347       // note that the inserted guy is never affected by a change or deletion
1348       ins_idx = -1;
1349       src_type = insert_type;
1350       fix_null_src_type = true;
1351       --src_idx;                // back up to process src type on next loop
1352       src_idx = src_end;
1353     } else {
1354       // note that the changed guy can be immediately deleted
1355       if (chg_idx == src_idx) {
1356         chg_idx = -1;
1357         assert(src_idx < src_end, "oob");
1358         src_type = change_type;
1359         fix_null_src_type = true;
1360       }
1361       if (del_idx == src_idx) {
1362         del_idx = -1;
1363         assert(src_idx < src_end, "oob");
1364         --dst_idx;
1365         continue;               // rerun loop after skipping this position
1366       }
1367     }
1368 
1369     if (src_type == NULL && fix_null_src_type)
1370       // explicit null in this case matches any dest reference
1371       src_type = (java_lang_Class::is_primitive(dst_type) ? object_java_mirror() : dst_type);
1372 
1373     // Compare the two argument types.
1374     if (src_type != dst_type) {
1375       if (src_type == NULL)  return "not enough arguments";
1376       if (dst_type == NULL)  return "too many arguments";
1377       err = check_argument_type_change(src_type, dst_type, dst_idx, raw);
1378       if (err != NULL)  return err;
1379     }
1380   }
1381 
1382   // Now compare return types also.
1383   oop src_rtype = java_lang_invoke_MethodType::rtype(src_mtype);
1384   oop dst_rtype = java_lang_invoke_MethodType::rtype(dst_mtype);
1385   if (src_rtype != dst_rtype) {
1386     err = check_return_type_change(dst_rtype, src_rtype, raw); // note reversal!
1387     if (err != NULL)  return err;
1388   }
1389 
1390   assert(err == NULL, "");
1391   return NULL;  // all is well
1392 }
1393 
1394 
1395 const char* MethodHandles::check_argument_type_change(BasicType src_type,
1396                                                       klassOop src_klass,
1397                                                       BasicType dst_type,
1398                                                       klassOop dst_klass,
1399                                                       int argnum,
1400                                                       bool raw) {
1401   const char* err = NULL;
1402   bool for_return = (argnum < 0);
1403 
1404   // just in case:
1405   if (src_type == T_ARRAY)  src_type = T_OBJECT;
1406   if (dst_type == T_ARRAY)  dst_type = T_OBJECT;
1407 
1408   // Produce some nice messages if VerifyMethodHandles is turned on:
1409   if (!same_basic_type_for_arguments(src_type, dst_type, raw, for_return)) {
1410     if (src_type == T_OBJECT) {
1411       if (raw && dst_type == T_INT && is_always_null_type(src_klass))
1412         return NULL;    // OK to convert a null pointer to a garbage int
1413       err = ((argnum >= 0)
1414              ? "type mismatch: passing a %s for method argument #%d, which expects primitive %s"
1415              : "type mismatch: returning a %s, but caller expects primitive %s");
1416     } else if (dst_type == T_OBJECT) {
1417       err = ((argnum >= 0)
1418              ? "type mismatch: passing a primitive %s for method argument #%d, which expects %s"
1419              : "type mismatch: returning a primitive %s, but caller expects %s");
1420     } else {
1421       err = ((argnum >= 0)
1422              ? "type mismatch: passing a %s for method argument #%d, which expects %s"
1423              : "type mismatch: returning a %s, but caller expects %s");
1424     }
1425   } else if (src_type == T_OBJECT && dst_type == T_OBJECT &&
1426              class_cast_needed(src_klass, dst_klass)) {
1427     if (!class_cast_needed(dst_klass, src_klass)) {
1428       if (raw)
1429         return NULL;    // reverse cast is OK; the MH target is trusted to enforce it
1430       err = ((argnum >= 0)
1431              ? "cast required: passing a %s for method argument #%d, which expects %s"
1432              : "cast required: returning a %s, but caller expects %s");
1433     } else {
1434       err = ((argnum >= 0)
1435              ? "reference mismatch: passing a %s for method argument #%d, which expects %s"
1436              : "reference mismatch: returning a %s, but caller expects %s");
1437     }
1438   } else {
1439     // passed the obstacle course
1440     return NULL;
1441   }
1442 
1443   // format, format, format
1444   const char* src_name = type2name(src_type);
1445   const char* dst_name = type2name(dst_type);
1446   if (src_name == NULL)  src_name = "unknown type";
1447   if (dst_name == NULL)  dst_name = "unknown type";
1448   if (src_type == T_OBJECT)
1449     src_name = (src_klass != NULL) ? Klass::cast(src_klass)->external_name() : "an unresolved class";
1450   if (dst_type == T_OBJECT)
1451     dst_name = (dst_klass != NULL) ? Klass::cast(dst_klass)->external_name() : "an unresolved class";
1452 
1453   size_t msglen = strlen(err) + strlen(src_name) + strlen(dst_name) + (argnum < 10 ? 1 : 11);
1454   char* msg = NEW_RESOURCE_ARRAY(char, msglen + 1);
1455   if (argnum >= 0) {
1456     assert(strstr(err, "%d") != NULL, "");
1457     jio_snprintf(msg, msglen, err, src_name, argnum, dst_name);
1458   } else {
1459     assert(strstr(err, "%d") == NULL, "");
1460     jio_snprintf(msg, msglen, err, src_name,         dst_name);
1461   }
1462   return msg;
1463 }
1464 
1465 // Compute the depth within the stack of the given argument, i.e.,
1466 // the combined size of arguments to the right of the given argument.
1467 // For the last argument (ptypes.length-1) this will be zero.
1468 // For the first argument (0) this will be the size of all
1469 // arguments but that one.  For the special number -1, this
1470 // will be the size of all arguments, including the first.
1471 // If the argument is neither -1 nor a valid argument index,
1472 // then return a negative number.  Otherwise, the result
1473 // is in the range [0..vmslots] inclusive.
1474 int MethodHandles::argument_slot(oop method_type, int arg) {
1475   objArrayOop ptypes = java_lang_invoke_MethodType::ptypes(method_type);
1476   int argslot = 0;
1477   int len = ptypes->length();
1478   if (arg < -1 || arg >= len)  return -99;
1479   for (int i = len-1; i > arg; i--) {
1480     BasicType bt = java_lang_Class::as_BasicType(ptypes->obj_at(i));
1481     argslot += type2size[bt];
1482   }
1483   assert(argument_slot_to_argnum(method_type, argslot) == arg, "inverse works");
1484   return argslot;
1485 }
1486 
1487 // Given a slot number, return the argument number.
1488 int MethodHandles::argument_slot_to_argnum(oop method_type, int query_argslot) {
1489   objArrayOop ptypes = java_lang_invoke_MethodType::ptypes(method_type);
1490   int argslot = 0;
1491   int len = ptypes->length();
1492   for (int i = len-1; i >= 0; i--) {
1493     if (query_argslot == argslot)  return i;
1494     BasicType bt = java_lang_Class::as_BasicType(ptypes->obj_at(i));
1495     argslot += type2size[bt];
1496   }
1497   // return pseudo-arg deepest in stack:
1498   if (query_argslot == argslot)  return -1;
1499   return -99;                   // oob slot, or splitting a double-slot arg
1500 }
1501 
1502 methodHandle MethodHandles::dispatch_decoded_method(methodHandle m,
1503                                                     KlassHandle receiver_limit,
1504                                                     int decode_flags,
1505                                                     KlassHandle receiver_klass,
1506                                                     TRAPS) {
1507   assert((decode_flags & ~_DMF_DIRECT_MASK) == 0, "must be direct method reference");
1508   assert((decode_flags & _dmf_has_receiver) != 0, "must have a receiver or first reference argument");
1509 
1510   if (!m->is_static() &&
1511       (receiver_klass.is_null() || !receiver_klass->is_subtype_of(m->method_holder())))
1512     // given type does not match class of method, or receiver is null!
1513     // caller should have checked this, but let's be extra careful...
1514     return methodHandle();
1515 
1516   if (receiver_limit.not_null() &&
1517       (receiver_klass.not_null() && !receiver_klass->is_subtype_of(receiver_limit())))
1518     // given type is not limited to the receiver type
1519     // note that a null receiver can match any reference value, for a static method
1520     return methodHandle();
1521 
1522   if (!(decode_flags & MethodHandles::_dmf_does_dispatch)) {
1523     // pre-dispatched or static method (null receiver is OK for static)
1524     return m;
1525 
1526   } else if (receiver_klass.is_null()) {
1527     // null receiver value; cannot dispatch
1528     return methodHandle();
1529 
1530   } else if (!(decode_flags & MethodHandles::_dmf_from_interface)) {
1531     // perform virtual dispatch
1532     int vtable_index = m->vtable_index();
1533     guarantee(vtable_index >= 0, "valid vtable index");
1534 
1535     // receiver_klass might be an arrayKlassOop but all vtables start at
1536     // the same place. The cast is to avoid virtual call and assertion.
1537     // See also LinkResolver::runtime_resolve_virtual_method.
1538     instanceKlass* inst = (instanceKlass*)Klass::cast(receiver_klass());
1539     DEBUG_ONLY(inst->verify_vtable_index(vtable_index));
1540     methodOop m_oop = inst->method_at_vtable(vtable_index);
1541     return methodHandle(THREAD, m_oop);
1542 
1543   } else {
1544     // perform interface dispatch
1545     int itable_index = klassItable::compute_itable_index(m());
1546     guarantee(itable_index >= 0, "valid itable index");
1547     instanceKlass* inst = instanceKlass::cast(receiver_klass());
1548     methodOop m_oop = inst->method_at_itable(m->method_holder(), itable_index, THREAD);
1549     return methodHandle(THREAD, m_oop);
1550   }
1551 }
1552 
1553 void MethodHandles::verify_DirectMethodHandle(Handle mh, methodHandle m, TRAPS) {
1554   // Verify type.
1555   Handle mtype(THREAD, java_lang_invoke_MethodHandle::type(mh()));
1556   verify_method_type(m, mtype, false, KlassHandle(), CHECK);
1557 
1558   // Verify vmslots.
1559   if (java_lang_invoke_MethodHandle::vmslots(mh()) != m->size_of_parameters()) {
1560     THROW_MSG(vmSymbols::java_lang_InternalError(), "bad vmslots in DMH");
1561   }
1562 }
1563 
1564 void MethodHandles::init_DirectMethodHandle(Handle mh, methodHandle m, bool do_dispatch, TRAPS) {
1565   // Check arguments.
1566   if (mh.is_null() || m.is_null() ||
1567       (!do_dispatch && m->is_abstract())) {
1568     THROW(vmSymbols::java_lang_InternalError());
1569   }
1570 
1571   java_lang_invoke_MethodHandle::init_vmslots(mh());
1572 
1573   if (VerifyMethodHandles) {
1574     // The privileged code which invokes this routine should not make
1575     // a mistake about types, but it's better to verify.
1576     verify_DirectMethodHandle(mh, m, CHECK);
1577   }
1578 
1579   // Finally, after safety checks are done, link to the target method.
1580   // We will follow the same path as the latter part of
1581   // InterpreterRuntime::resolve_invoke(), which first finds the method
1582   // and then decides how to populate the constant pool cache entry
1583   // that links the interpreter calls to the method.  We need the same
1584   // bits, and will use the same calling sequence code.
1585 
1586   int    vmindex = methodOopDesc::garbage_vtable_index;
1587   Handle vmtarget;
1588 
1589   instanceKlass::cast(m->method_holder())->link_class(CHECK);
1590 
1591   MethodHandleEntry* me = NULL;
1592   if (do_dispatch && Klass::cast(m->method_holder())->is_interface()) {
1593     // We are simulating an invokeinterface instruction.
1594     // (We might also be simulating an invokevirtual on a miranda method,
1595     // but it is safe to treat it as an invokeinterface.)
1596     assert(!m->can_be_statically_bound(), "no final methods on interfaces");
1597     vmindex = klassItable::compute_itable_index(m());
1598     assert(vmindex >= 0, "(>=0) == do_dispatch");
1599     // Set up same bits as ConstantPoolCacheEntry::set_interface_call().
1600     vmtarget = m->method_holder(); // the interface
1601     me = MethodHandles::entry(MethodHandles::_invokeinterface_mh);
1602   } else if (!do_dispatch || m->can_be_statically_bound()) {
1603     // We are simulating an invokestatic or invokespecial instruction.
1604     // Set up the method pointer, just like ConstantPoolCacheEntry::set_method().
1605     vmtarget = m;
1606     // this does not help dispatch, but it will make it possible to parse this MH:
1607     vmindex  = methodOopDesc::nonvirtual_vtable_index;
1608     assert(vmindex < 0, "(>=0) == do_dispatch");
1609     if (!m->is_static()) {
1610       me = MethodHandles::entry(MethodHandles::_invokespecial_mh);
1611     } else {
1612       me = MethodHandles::entry(MethodHandles::_invokestatic_mh);
1613       // Part of the semantics of a static call is an initialization barrier.
1614       // For a DMH, it is done now, when the handle is created.
1615       Klass* k = Klass::cast(m->method_holder());
1616       if (k->should_be_initialized()) {
1617         k->initialize(CHECK);  // possible safepoint
1618       }
1619     }
1620   } else {
1621     // We are simulating an invokevirtual instruction.
1622     // Set up the vtable index, just like ConstantPoolCacheEntry::set_method().
1623     // The key logic is LinkResolver::runtime_resolve_virtual_method.
1624     vmindex  = m->vtable_index();
1625     vmtarget = m->method_holder();
1626     me = MethodHandles::entry(MethodHandles::_invokevirtual_mh);
1627   }
1628 
1629   if (me == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
1630 
1631   java_lang_invoke_DirectMethodHandle::set_vmtarget(mh(), vmtarget());
1632   java_lang_invoke_DirectMethodHandle::set_vmindex( mh(), vmindex);
1633   DEBUG_ONLY(KlassHandle rlimit; int flags);
1634   assert(MethodHandles::decode_method(mh(), rlimit, flags) == m,
1635          "properly stored for later decoding");
1636   DEBUG_ONLY(bool actual_do_dispatch = ((flags & _dmf_does_dispatch) != 0));
1637   assert(!(actual_do_dispatch && !do_dispatch),
1638          "do not perform dispatch if !do_dispatch specified");
1639   assert(actual_do_dispatch == (vmindex >= 0), "proper later decoding of do_dispatch");
1640   assert(decode_MethodHandle_stack_pushes(mh()) == 0, "DMH does not move stack");
1641 
1642   // Done!
1643   java_lang_invoke_MethodHandle::set_vmentry(mh(), me);
1644 }
1645 
1646 void MethodHandles::verify_BoundMethodHandle_with_receiver(Handle mh,
1647                                                            methodHandle m,
1648                                                            TRAPS) {
1649   // Verify type.
1650   KlassHandle bound_recv_type;
1651   {
1652     oop receiver = java_lang_invoke_BoundMethodHandle::argument(mh());
1653     if (receiver != NULL)
1654       bound_recv_type = KlassHandle(THREAD, receiver->klass());
1655   }
1656   Handle mtype(THREAD, java_lang_invoke_MethodHandle::type(mh()));
1657   verify_method_type(m, mtype, true, bound_recv_type, CHECK);
1658 
1659   int receiver_pos = m->size_of_parameters() - 1;
1660 
1661   // Verify MH.vmargslot, which should point at the bound receiver.
1662   verify_vmargslot(mh, -1, java_lang_invoke_BoundMethodHandle::vmargslot(mh()), CHECK);
1663   //verify_vmslots(mh, CHECK);
1664 
1665   // Verify vmslots.
1666   if (java_lang_invoke_MethodHandle::vmslots(mh()) != receiver_pos) {
1667     THROW_MSG(vmSymbols::java_lang_InternalError(), "bad vmslots in BMH (receiver)");
1668   }
1669 }
1670 
1671 // Initialize a BMH with a receiver bound directly to a methodOop.
1672 void MethodHandles::init_BoundMethodHandle_with_receiver(Handle mh,
1673                                                          methodHandle original_m,
1674                                                          KlassHandle receiver_limit,
1675                                                          int decode_flags,
1676                                                          TRAPS) {
1677   // Check arguments.
1678   if (mh.is_null() || original_m.is_null()) {
1679     THROW(vmSymbols::java_lang_InternalError());
1680   }
1681 
1682   KlassHandle receiver_klass;
1683   {
1684     oop receiver_oop = java_lang_invoke_BoundMethodHandle::argument(mh());
1685     if (receiver_oop != NULL)
1686       receiver_klass = KlassHandle(THREAD, receiver_oop->klass());
1687   }
1688   methodHandle m = dispatch_decoded_method(original_m,
1689                                            receiver_limit, decode_flags,
1690                                            receiver_klass,
1691                                            CHECK);
1692   if (m.is_null())      { THROW(vmSymbols::java_lang_InternalError()); }
1693   if (m->is_abstract()) { THROW(vmSymbols::java_lang_AbstractMethodError()); }
1694 
1695   java_lang_invoke_MethodHandle::init_vmslots(mh());
1696   int vmargslot = m->size_of_parameters() - 1;
1697   assert(java_lang_invoke_BoundMethodHandle::vmargslot(mh()) == vmargslot, "");
1698 
1699   if (VerifyMethodHandles) {
1700     verify_BoundMethodHandle_with_receiver(mh, m, CHECK);
1701   }
1702 
1703   java_lang_invoke_BoundMethodHandle::set_vmtarget(mh(), m());
1704 
1705   DEBUG_ONLY(KlassHandle junk1; int junk2);
1706   assert(MethodHandles::decode_method(mh(), junk1, junk2) == m, "properly stored for later decoding");
1707   assert(decode_MethodHandle_stack_pushes(mh()) == 1, "BMH pushes one stack slot");
1708 
1709   // Done!
1710   java_lang_invoke_MethodHandle::set_vmentry(mh(), MethodHandles::entry(MethodHandles::_bound_ref_direct_mh));
1711 }
1712 
1713 void MethodHandles::verify_BoundMethodHandle(Handle mh, Handle target, int argnum,
1714                                              bool direct_to_method, TRAPS) {
1715   Handle ptype_handle(THREAD,
1716                            java_lang_invoke_MethodType::ptype(java_lang_invoke_MethodHandle::type(target()), argnum));
1717   KlassHandle ptype_klass;
1718   BasicType ptype = java_lang_Class::as_BasicType(ptype_handle(), &ptype_klass);
1719   int slots_pushed = type2size[ptype];
1720 
1721   oop argument = java_lang_invoke_BoundMethodHandle::argument(mh());
1722 
1723   const char* err = NULL;
1724 
1725   switch (ptype) {
1726   case T_OBJECT:
1727     if (argument != NULL)
1728       // we must implicitly convert from the arg type to the outgoing ptype
1729       err = check_argument_type_change(T_OBJECT, argument->klass(), ptype, ptype_klass(), argnum);
1730     break;
1731 
1732   case T_ARRAY: case T_VOID:
1733     assert(false, "array, void do not appear here");
1734   default:
1735     if (ptype != T_INT && !is_subword_type(ptype)) {
1736       err = "unexpected parameter type";
1737       break;
1738     }
1739     // check subrange of Integer.value, if necessary
1740     if (argument == NULL || argument->klass() != SystemDictionary::Integer_klass()) {
1741       err = "bound integer argument must be of type java.lang.Integer";
1742       break;
1743     }
1744     if (ptype != T_INT) {
1745       int value_offset = java_lang_boxing_object::value_offset_in_bytes(T_INT);
1746       jint value = argument->int_field(value_offset);
1747       int vminfo = adapter_unbox_subword_vminfo(ptype);
1748       jint subword = truncate_subword_from_vminfo(value, vminfo);
1749       if (value != subword) {
1750         err = "bound subword value does not fit into the subword type";
1751         break;
1752       }
1753     }
1754     break;
1755   case T_FLOAT:
1756   case T_DOUBLE:
1757   case T_LONG:
1758     {
1759       // we must implicitly convert from the unboxed arg type to the outgoing ptype
1760       BasicType argbox = java_lang_boxing_object::basic_type(argument);
1761       if (argbox != ptype) {
1762         err = check_argument_type_change(T_OBJECT, (argument == NULL
1763                                                     ? SystemDictionary::Object_klass()
1764                                                     : argument->klass()),
1765                                          ptype, ptype_klass(), argnum);
1766         assert(err != NULL, "this must be an error");
1767       }
1768       break;
1769     }
1770   }
1771 
1772   if (err == NULL) {
1773     DEBUG_ONLY(int this_pushes = decode_MethodHandle_stack_pushes(mh()));
1774     if (direct_to_method) {
1775       assert(this_pushes == slots_pushed, "BMH pushes one or two stack slots");
1776     } else {
1777       int target_pushes = decode_MethodHandle_stack_pushes(target());
1778       assert(this_pushes == slots_pushed + target_pushes, "BMH stack motion must be correct");
1779     }
1780   }
1781 
1782   if (err == NULL) {
1783     // Verify the rest of the method type.
1784     err = check_method_type_insertion(java_lang_invoke_MethodHandle::type(mh()),
1785                                       argnum, ptype_handle(),
1786                                       java_lang_invoke_MethodHandle::type(target()));
1787   }
1788 
1789   if (err != NULL) {
1790     THROW_MSG(vmSymbols::java_lang_InternalError(), err);
1791   }
1792 }
1793 
1794 void MethodHandles::init_BoundMethodHandle(Handle mh, Handle target, int argnum, TRAPS) {
1795   // Check arguments.
1796   if (mh.is_null() || target.is_null() || !java_lang_invoke_MethodHandle::is_instance(target())) {
1797     THROW(vmSymbols::java_lang_InternalError());
1798   }
1799 
1800   java_lang_invoke_MethodHandle::init_vmslots(mh());
1801   int argslot = java_lang_invoke_BoundMethodHandle::vmargslot(mh());
1802 
1803   if (VerifyMethodHandles) {
1804     int insert_after = argnum - 1;
1805     verify_vmargslot(mh, insert_after, argslot, CHECK);
1806     verify_vmslots(mh, CHECK);
1807   }
1808 
1809   // Get bound type and required slots.
1810   BasicType ptype;
1811   {
1812     oop ptype_oop = java_lang_invoke_MethodType::ptype(java_lang_invoke_MethodHandle::type(target()), argnum);
1813     ptype = java_lang_Class::as_BasicType(ptype_oop);
1814   }
1815   int slots_pushed = type2size[ptype];
1816 
1817   // If (a) the target is a direct non-dispatched method handle,
1818   // or (b) the target is a dispatched direct method handle and we
1819   // are binding the receiver, cut out the middle-man.
1820   // Do this by decoding the DMH and using its methodOop directly as vmtarget.
1821   bool direct_to_method = false;
1822   if (OptimizeMethodHandles &&
1823       target->klass() == SystemDictionary::DirectMethodHandle_klass() &&
1824       (argnum == 0 || java_lang_invoke_DirectMethodHandle::vmindex(target()) < 0)) {
1825     KlassHandle receiver_limit; int decode_flags = 0;
1826     methodHandle m = decode_method(target(), receiver_limit, decode_flags);
1827     if (m.is_null()) { THROW_MSG(vmSymbols::java_lang_InternalError(), "DMH failed to decode"); }
1828     DEBUG_ONLY(int m_vmslots = m->size_of_parameters() - slots_pushed); // pos. of 1st arg.
1829     assert(java_lang_invoke_BoundMethodHandle::vmslots(mh()) == m_vmslots, "type w/ m sig");
1830     if (argnum == 0 && (decode_flags & _dmf_has_receiver) != 0) {
1831       init_BoundMethodHandle_with_receiver(mh, m,
1832                                            receiver_limit, decode_flags,
1833                                            CHECK);
1834       return;
1835     }
1836 
1837     // Even if it is not a bound receiver, we still might be able
1838     // to bind another argument and still invoke the methodOop directly.
1839     if (!(decode_flags & _dmf_does_dispatch)) {
1840       direct_to_method = true;
1841       java_lang_invoke_BoundMethodHandle::set_vmtarget(mh(), m());
1842     }
1843   }
1844   if (!direct_to_method)
1845     java_lang_invoke_BoundMethodHandle::set_vmtarget(mh(), target());
1846 
1847   if (VerifyMethodHandles) {
1848     verify_BoundMethodHandle(mh, target, argnum, direct_to_method, CHECK);
1849   }
1850 
1851   // Next question:  Is this a ref, int, or long bound value?
1852   MethodHandleEntry* me = NULL;
1853   if (ptype == T_OBJECT) {
1854     if (direct_to_method)  me = MethodHandles::entry(_bound_ref_direct_mh);
1855     else                   me = MethodHandles::entry(_bound_ref_mh);
1856   } else if (slots_pushed == 2) {
1857     if (direct_to_method)  me = MethodHandles::entry(_bound_long_direct_mh);
1858     else                   me = MethodHandles::entry(_bound_long_mh);
1859   } else if (slots_pushed == 1) {
1860     if (direct_to_method)  me = MethodHandles::entry(_bound_int_direct_mh);
1861     else                   me = MethodHandles::entry(_bound_int_mh);
1862   } else {
1863     assert(false, "");
1864   }
1865 
1866   // Done!
1867   java_lang_invoke_MethodHandle::set_vmentry(mh(), me);
1868 }
1869 
1870 static void throw_InternalError_for_bad_conversion(int conversion, const char* err, TRAPS) {
1871   char msg[200];
1872   jio_snprintf(msg, sizeof(msg), "bad adapter (conversion=0x%08x): %s", conversion, err);
1873   THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), msg);
1874 }
1875 
1876 void MethodHandles::verify_AdapterMethodHandle(Handle mh, int argnum, TRAPS) {
1877   jint conversion = java_lang_invoke_AdapterMethodHandle::conversion(mh());
1878   int  argslot    = java_lang_invoke_AdapterMethodHandle::vmargslot(mh());
1879 
1880   verify_vmargslot(mh, argnum, argslot, CHECK);
1881   verify_vmslots(mh, CHECK);
1882 
1883   jint conv_op    = adapter_conversion_op(conversion);
1884   if (!conv_op_valid(conv_op)) {
1885     throw_InternalError_for_bad_conversion(conversion, "unknown conversion op", THREAD);
1886     return;
1887   }
1888   EntryKind ek = adapter_entry_kind(conv_op);
1889 
1890   int stack_move = adapter_conversion_stack_move(conversion);
1891   BasicType src  = adapter_conversion_src_type(conversion);
1892   BasicType dest = adapter_conversion_dest_type(conversion);
1893   int vminfo     = adapter_conversion_vminfo(conversion); // should be zero
1894 
1895   Handle argument(THREAD,  java_lang_invoke_AdapterMethodHandle::argument(mh()));
1896   Handle target(THREAD,    java_lang_invoke_AdapterMethodHandle::vmtarget(mh()));
1897   Handle src_mtype(THREAD, java_lang_invoke_MethodHandle::type(mh()));
1898   Handle dst_mtype(THREAD, java_lang_invoke_MethodHandle::type(target()));
1899   Handle arg_mtype;
1900 
1901   const char* err = NULL;
1902 
1903   if (err == NULL) {
1904     // Check that the correct argument is supplied, but only if it is required.
1905     switch (ek) {
1906     case _adapter_check_cast:     // target type of cast
1907     case _adapter_ref_to_prim:    // wrapper type from which to unbox
1908     case _adapter_spread_args:    // array type to spread from
1909       if (!java_lang_Class::is_instance(argument())
1910           || java_lang_Class::is_primitive(argument()))
1911         { err = "adapter requires argument of type java.lang.Class"; break; }
1912       if (ek == _adapter_spread_args) {
1913         // Make sure it is a suitable collection type.  (Array, for now.)
1914         Klass* ak = Klass::cast(java_lang_Class::as_klassOop(argument()));
1915         if (!ak->oop_is_array())
1916           { err = "spread adapter requires argument representing an array class"; break; }
1917         BasicType et = arrayKlass::cast(ak->as_klassOop())->element_type();
1918         if (et != dest && stack_move <= 0)
1919           { err = "spread adapter requires array class argument of correct type"; break; }
1920       }
1921       break;
1922     case _adapter_prim_to_ref:    // boxer MH to use
1923     case _adapter_collect_args:   // method handle which collects the args
1924     case _adapter_fold_args:      // method handle which collects the args
1925       if (!UseRicochetFrames) {
1926         { err = "box/collect/fold operators are not supported"; break; }
1927       }
1928       if (!java_lang_invoke_MethodHandle::is_instance(argument()))
1929         { err = "MethodHandle adapter argument required"; break; }
1930       arg_mtype = Handle(THREAD, java_lang_invoke_MethodHandle::type(argument()));
1931       break;
1932     default:
1933       if (argument.not_null())
1934         { err = "adapter has spurious argument"; break; }
1935       break;
1936     }
1937   }
1938 
1939   if (err == NULL) {
1940     // Check that the src/dest types are supplied if needed.
1941     // Also check relevant parameter or return types.
1942     switch (ek) {
1943     case _adapter_check_cast:
1944       if (src != T_OBJECT || dest != T_OBJECT) {
1945         err = "adapter requires object src/dest conversion subfields";
1946       }
1947       break;
1948     case _adapter_prim_to_prim:
1949       if (!is_java_primitive(src) || !is_java_primitive(dest) || src == dest) {
1950         err = "adapter requires primitive src/dest conversion subfields"; break;
1951       }
1952       if ( (src == T_FLOAT || src == T_DOUBLE) && !(dest == T_FLOAT || dest == T_DOUBLE) ||
1953           !(src == T_FLOAT || src == T_DOUBLE) &&  (dest == T_FLOAT || dest == T_DOUBLE)) {
1954         err = "adapter cannot convert beween floating and fixed-point"; break;
1955       }
1956       break;
1957     case _adapter_ref_to_prim:
1958       if (src != T_OBJECT || !is_java_primitive(dest)
1959           || argument() != Klass::cast(SystemDictionary::box_klass(dest))->java_mirror()) {
1960         err = "adapter requires primitive dest conversion subfield"; break;
1961       }
1962       break;
1963     case _adapter_prim_to_ref:
1964       if (!is_java_primitive(src) || dest != T_OBJECT) {
1965         err = "adapter requires primitive src conversion subfield"; break;
1966       }
1967       break;
1968     case _adapter_swap_args:
1969     case _adapter_rot_args:
1970       {
1971         if (!src || src != dest) {
1972           err = "adapter requires src/dest conversion subfields for swap"; break;
1973         }
1974         int swap_size = type2size[src];
1975         int slot_limit = java_lang_invoke_MethodHandle::vmslots(target());
1976         int src_slot   = argslot;
1977         int dest_slot  = vminfo;
1978         bool rotate_up = (src_slot > dest_slot); // upward rotation
1979         int src_arg    = argnum;
1980         int dest_arg   = argument_slot_to_argnum(dst_mtype(), dest_slot);
1981         verify_vmargslot(mh, dest_arg, dest_slot, CHECK);
1982         if (!(dest_slot >= src_slot + swap_size) &&
1983             !(src_slot >= dest_slot + swap_size)) {
1984           err = "source, destination slots must be distinct";
1985         } else if (ek == _adapter_swap_args && !(src_slot > dest_slot)) {
1986           err = "source of swap must be deeper in stack";
1987         } else if (ek == _adapter_swap_args) {
1988           err = check_argument_type_change(java_lang_invoke_MethodType::ptype(src_mtype(), dest_arg),
1989                                            java_lang_invoke_MethodType::ptype(dst_mtype(), src_arg),
1990                                            dest_arg);
1991         } else if (ek == _adapter_rot_args) {
1992           if (rotate_up) {
1993             assert((src_slot > dest_slot) && (src_arg < dest_arg), "");
1994             // rotate up: [dest_slot..src_slot-ss] --> [dest_slot+ss..src_slot]
1995             // that is:   [src_arg+1..dest_arg] --> [src_arg..dest_arg-1]
1996             for (int i = src_arg+1; i <= dest_arg && err == NULL; i++) {
1997               err = check_argument_type_change(java_lang_invoke_MethodType::ptype(src_mtype(), i),
1998                                                java_lang_invoke_MethodType::ptype(dst_mtype(), i-1),
1999                                                i);
2000             }
2001           } else { // rotate down
2002             assert((src_slot < dest_slot) && (src_arg > dest_arg), "");
2003             // rotate down: [src_slot+ss..dest_slot] --> [src_slot..dest_slot-ss]
2004             // that is:     [dest_arg..src_arg-1] --> [dst_arg+1..src_arg]
2005             for (int i = dest_arg; i <= src_arg-1 && err == NULL; i++) {
2006               err = check_argument_type_change(java_lang_invoke_MethodType::ptype(src_mtype(), i),
2007                                                java_lang_invoke_MethodType::ptype(dst_mtype(), i+1),
2008                                                i);
2009             }
2010           }
2011         }
2012         if (err == NULL)
2013           err = check_argument_type_change(java_lang_invoke_MethodType::ptype(src_mtype(), src_arg),
2014                                            java_lang_invoke_MethodType::ptype(dst_mtype(), dest_arg),
2015                                            src_arg);
2016       }
2017       break;
2018     case _adapter_spread_args:
2019     case _adapter_collect_args:
2020     case _adapter_fold_args:
2021       {
2022         bool is_spread = (ek == _adapter_spread_args);
2023         bool is_fold   = (ek == _adapter_fold_args);
2024         BasicType coll_type = is_spread ? src : dest;
2025         BasicType elem_type = is_spread ? dest : src;
2026         // coll_type is type of args in collected form (or T_VOID if none)
2027         // elem_type is common type of args in spread form (or T_VOID if missing or heterogeneous)
2028         if (coll_type == 0 || elem_type == 0) {
2029           err = "adapter requires src/dest subfields for spread or collect"; break;
2030         }
2031         if (is_spread && coll_type != T_OBJECT) {
2032           err = "spread adapter requires object type for argument bundle"; break;
2033         }
2034         Handle spread_mtype = (is_spread ? dst_mtype : src_mtype);
2035         int spread_slot = argslot;
2036         int spread_arg  = argnum;
2037         int slots_pushed = stack_move / stack_move_unit();
2038         int coll_slot_count = type2size[coll_type];
2039         int spread_slot_count = (is_spread ? slots_pushed : -slots_pushed) + coll_slot_count;
2040         if (is_fold)  spread_slot_count = argument_slot_count(arg_mtype());
2041         if (!is_spread) {
2042           int init_slots = argument_slot_count(src_mtype());
2043           int coll_slots = argument_slot_count(arg_mtype());
2044           if (spread_slot_count > init_slots ||
2045               spread_slot_count != coll_slots) {
2046             err = "collect adapter has inconsistent arg counts"; break;
2047           }
2048           int next_slots = argument_slot_count(dst_mtype());
2049           int unchanged_slots_in  = (init_slots - spread_slot_count);
2050           int unchanged_slots_out = (next_slots - coll_slot_count - (is_fold ? spread_slot_count : 0));
2051           if (unchanged_slots_in != unchanged_slots_out) {
2052             err = "collect adapter continuation has inconsistent arg counts"; break;
2053           }
2054         }
2055       }
2056       break;
2057     default:
2058       if (src != 0 || dest != 0) {
2059         err = "adapter has spurious src/dest conversion subfields"; break;
2060       }
2061       break;
2062     }
2063   }
2064 
2065   if (err == NULL) {
2066     // Check the stack_move subfield.
2067     // It must always report the net change in stack size, positive or negative.
2068     int slots_pushed = stack_move / stack_move_unit();
2069     switch (ek) {
2070     case _adapter_prim_to_prim:
2071     case _adapter_ref_to_prim:
2072     case _adapter_prim_to_ref:
2073       if (slots_pushed != type2size[dest] - type2size[src]) {
2074         err = "wrong stack motion for primitive conversion";
2075       }
2076       break;
2077     case _adapter_dup_args:
2078       if (slots_pushed <= 0) {
2079         err = "adapter requires conversion subfield slots_pushed > 0";
2080       }
2081       break;
2082     case _adapter_drop_args:
2083       if (slots_pushed >= 0) {
2084         err = "adapter requires conversion subfield slots_pushed < 0";
2085       }
2086       break;
2087     case _adapter_collect_args:
2088     case _adapter_fold_args:
2089       if (slots_pushed > 2) {
2090         err = "adapter requires conversion subfield slots_pushed <= 2";
2091       }
2092       break;
2093     case _adapter_spread_args:
2094       if (slots_pushed < -1) {
2095         err = "adapter requires conversion subfield slots_pushed >= -1";
2096       }
2097       break;
2098     default:
2099       if (stack_move != 0) {
2100         err = "adapter has spurious stack_move conversion subfield";
2101       }
2102       break;
2103     }
2104     if (err == NULL && stack_move != slots_pushed * stack_move_unit()) {
2105       err = "stack_move conversion subfield must be multiple of stack_move_unit";
2106     }
2107   }
2108 
2109   if (err == NULL) {
2110     // Make sure this adapter's stack pushing is accurately recorded.
2111     int slots_pushed = stack_move / stack_move_unit();
2112     int this_vmslots = java_lang_invoke_MethodHandle::vmslots(mh());
2113     int target_vmslots = java_lang_invoke_MethodHandle::vmslots(target());
2114     int target_pushes = decode_MethodHandle_stack_pushes(target());
2115     if (slots_pushed != (target_vmslots - this_vmslots)) {
2116       err = "stack_move inconsistent with previous and current MethodType vmslots";
2117     } else {
2118       int this_pushes = decode_MethodHandle_stack_pushes(mh());
2119       if (slots_pushed + target_pushes != this_pushes) {
2120         if (this_pushes == 0)
2121           err = "adapter push count not initialized";
2122         else
2123           err = "adapter push count is wrong";
2124       }
2125     }
2126 
2127     // While we're at it, check that the stack motion decoder works:
2128     DEBUG_ONLY(int this_pushes = decode_MethodHandle_stack_pushes(mh()));
2129     assert(this_pushes == slots_pushed + target_pushes, "AMH stack motion must be correct");
2130   }
2131 
2132   if (err == NULL && vminfo != 0) {
2133     switch (ek) {
2134     case _adapter_swap_args:
2135     case _adapter_rot_args:
2136     case _adapter_prim_to_ref:
2137     case _adapter_collect_args:
2138     case _adapter_fold_args:
2139       break;                // OK
2140     default:
2141       err = "vminfo subfield is reserved to the JVM";
2142     }
2143   }
2144 
2145   // Do additional ad hoc checks.
2146   if (err == NULL) {
2147     switch (ek) {
2148     case _adapter_retype_only:
2149       err = check_method_type_passthrough(src_mtype(), dst_mtype(), false);
2150       break;
2151 
2152     case _adapter_retype_raw:
2153       err = check_method_type_passthrough(src_mtype(), dst_mtype(), true);
2154       break;
2155 
2156     case _adapter_check_cast:
2157       {
2158         // The actual value being checked must be a reference:
2159         err = check_argument_type_change(java_lang_invoke_MethodType::ptype(src_mtype(), argnum),
2160                                          object_java_mirror(), argnum);
2161         if (err != NULL)  break;
2162 
2163         // The output of the cast must fit with the destination argument:
2164         Handle cast_class = argument;
2165         err = check_method_type_conversion(src_mtype(),
2166                                            argnum, cast_class(),
2167                                            dst_mtype());
2168       }
2169       break;
2170 
2171       // %%% TO DO: continue in remaining cases to verify src/dst_mtype if VerifyMethodHandles
2172     }
2173   }
2174 
2175   if (err != NULL) {
2176     throw_InternalError_for_bad_conversion(conversion, err, THREAD);
2177     return;
2178   }
2179 
2180 }
2181 
2182 void MethodHandles::init_AdapterMethodHandle(Handle mh, Handle target, int argnum, TRAPS) {
2183   int  argslot    = java_lang_invoke_AdapterMethodHandle::vmargslot(mh());
2184   jint conversion = java_lang_invoke_AdapterMethodHandle::conversion(mh());
2185   jint conv_op    = adapter_conversion_op(conversion);
2186 
2187   // adjust the adapter code to the internal EntryKind enumeration:
2188   EntryKind ek_orig = adapter_entry_kind(conv_op);
2189   EntryKind ek_opt  = ek_orig;  // may be optimized
2190   EntryKind ek_try;             // temp
2191 
2192   // Finalize the vmtarget field (Java initialized it to null).
2193   if (!java_lang_invoke_MethodHandle::is_instance(target())) {
2194     throw_InternalError_for_bad_conversion(conversion, "bad target", THREAD);
2195     return;
2196   }
2197   java_lang_invoke_AdapterMethodHandle::set_vmtarget(mh(), target());
2198 
2199   int stack_move = adapter_conversion_stack_move(conversion);
2200   BasicType src  = adapter_conversion_src_type(conversion);
2201   BasicType dest = adapter_conversion_dest_type(conversion);
2202   int vminfo     = adapter_conversion_vminfo(conversion); // should be zero
2203 
2204   int slots_pushed = stack_move / stack_move_unit();
2205 
2206   if (VerifyMethodHandles) {
2207     verify_AdapterMethodHandle(mh, argnum, CHECK);
2208   }
2209 
2210   const char* err = NULL;
2211 
2212   if (!conv_op_supported(conv_op)) {
2213     err = "adapter not yet implemented in the JVM";
2214   }
2215 
2216   // Now it's time to finish the case analysis and pick a MethodHandleEntry.
2217   switch (ek_orig) {
2218   case _adapter_retype_only:
2219   case _adapter_retype_raw:
2220   case _adapter_check_cast:
2221   case _adapter_dup_args:
2222   case _adapter_drop_args:
2223     // these work fine via general case code
2224     break;
2225 
2226   case _adapter_prim_to_prim:
2227     {
2228       // Non-subword cases are {int,float,long,double} -> {int,float,long,double}.
2229       // And, the {float,double} -> {int,long} cases must be handled by Java.
2230       switch (type2size[src] *4+ type2size[dest]) {
2231       case 1 *4+ 1:
2232         assert(src == T_INT || is_subword_type(src), "source is not float");
2233         // Subword-related cases are int -> {boolean,byte,char,short}.
2234         ek_opt = _adapter_opt_i2i;
2235         vminfo = adapter_prim_to_prim_subword_vminfo(dest);
2236         break;
2237       case 2 *4+ 1:
2238         if (src == T_LONG && (dest == T_INT || is_subword_type(dest))) {
2239           ek_opt = _adapter_opt_l2i;
2240           vminfo = adapter_prim_to_prim_subword_vminfo(dest);
2241         } else if (src == T_DOUBLE && dest == T_FLOAT) {
2242           ek_opt = _adapter_opt_d2f;
2243         } else {
2244           assert(false, "");
2245         }
2246         break;
2247       case 1 *4+ 2:
2248         if ((src == T_INT || is_subword_type(src)) && dest == T_LONG) {
2249           ek_opt = _adapter_opt_i2l;
2250         } else if (src == T_FLOAT && dest == T_DOUBLE) {
2251           ek_opt = _adapter_opt_f2d;
2252         } else {
2253           assert(false, "");
2254         }
2255         break;
2256       default:
2257         assert(false, "");
2258         break;
2259       }
2260     }
2261     break;
2262 
2263   case _adapter_ref_to_prim:
2264     {
2265       switch (type2size[dest]) {
2266       case 1:
2267         ek_opt = _adapter_opt_unboxi;
2268         vminfo = adapter_unbox_subword_vminfo(dest);
2269         break;
2270       case 2:
2271         ek_opt = _adapter_opt_unboxl;
2272         break;
2273       default:
2274         assert(false, "");
2275         break;
2276       }
2277     }
2278     break;
2279 
2280   case _adapter_prim_to_ref:
2281     {
2282       assert(UseRicochetFrames, "else don't come here");
2283       // vminfo will be the location to insert the return value
2284       vminfo = argslot;
2285       ek_opt = _adapter_opt_collect_ref;
2286       ensure_vmlayout_field(target, CHECK);
2287       if (!OptimizeMethodHandles)  break;
2288       switch (type2size[src]) {
2289       case 1:
2290         ek_try = EntryKind(_adapter_opt_filter_S0_ref + argslot);
2291         if (ek_try < _adapter_opt_collect_LAST &&
2292             ek_adapter_opt_collect_slot(ek_try) == argslot) {
2293           assert(ek_adapter_opt_collect_count(ek_try) == 1 &&
2294                  ek_adapter_opt_collect_type(ek_try) == T_OBJECT, "");
2295           ek_opt = ek_try;
2296           break;
2297         }
2298         // else downgrade to variable slot:
2299         ek_opt = _adapter_opt_collect_1_ref;
2300         break;
2301       case 2:
2302         ek_try = EntryKind(_adapter_opt_collect_2_S0_ref + argslot);
2303         if (ek_try < _adapter_opt_collect_LAST &&
2304             ek_adapter_opt_collect_slot(ek_try) == argslot) {
2305           assert(ek_adapter_opt_collect_count(ek_try) == 2 &&
2306                  ek_adapter_opt_collect_type(ek_try) == T_OBJECT, "");
2307           ek_opt = ek_try;
2308           break;
2309         }
2310         // else downgrade to variable slot:
2311         ek_opt = _adapter_opt_collect_2_ref;
2312         break;
2313       default:
2314         assert(false, "");
2315         break;
2316       }
2317     }
2318     break;
2319 
2320   case _adapter_swap_args:
2321   case _adapter_rot_args:
2322     {
2323       int swap_slots = type2size[src];
2324       int slot_limit = java_lang_invoke_AdapterMethodHandle::vmslots(mh());
2325       int src_slot   = argslot;
2326       int dest_slot  = vminfo;
2327       int rotate     = (ek_orig == _adapter_swap_args) ? 0 : (src_slot > dest_slot) ? 1 : -1;
2328       switch (swap_slots) {
2329       case 1:
2330         ek_opt = (!rotate    ? _adapter_opt_swap_1 :
2331                   rotate > 0 ? _adapter_opt_rot_1_up : _adapter_opt_rot_1_down);
2332         break;
2333       case 2:
2334         ek_opt = (!rotate    ? _adapter_opt_swap_2 :
2335                   rotate > 0 ? _adapter_opt_rot_2_up : _adapter_opt_rot_2_down);
2336         break;
2337       default:
2338         assert(false, "");
2339         break;
2340       }
2341     }
2342     break;
2343 
2344   case _adapter_spread_args:
2345     {
2346 #ifdef TARGET_ARCH_NYI_6939861
2347       // ports before 6939861 supported only three kinds of spread ops
2348       if (!UseRicochetFrames) {
2349         int array_size   = slots_pushed + 1;
2350         assert(array_size >= 0, "");
2351         vminfo = array_size;
2352         switch (array_size) {
2353         case 0:   ek_opt = _adapter_opt_spread_0;       break;
2354         case 1:   ek_opt = _adapter_opt_spread_1;       break;
2355         default:  ek_opt = _adapter_opt_spread_more;    break;
2356         }
2357         break;
2358       }
2359 #endif //TARGET_ARCH_NYI_6939861
2360       // vminfo will be the required length of the array
2361       int array_size = (slots_pushed + 1) / (type2size[dest] == 2 ? 2 : 1);
2362       vminfo = array_size;
2363       // general case
2364       switch (dest) {
2365       case T_BOOLEAN : // fall through to T_BYTE:
2366       case T_BYTE    : ek_opt = _adapter_opt_spread_byte;    break;
2367       case T_CHAR    : ek_opt = _adapter_opt_spread_char;    break;
2368       case T_SHORT   : ek_opt = _adapter_opt_spread_short;   break;
2369       case T_INT     : ek_opt = _adapter_opt_spread_int;     break;
2370       case T_LONG    : ek_opt = _adapter_opt_spread_long;    break;
2371       case T_FLOAT   : ek_opt = _adapter_opt_spread_float;   break;
2372       case T_DOUBLE  : ek_opt = _adapter_opt_spread_double;  break;
2373       case T_OBJECT  : ek_opt = _adapter_opt_spread_ref;     break;
2374       case T_VOID    : if (array_size != 0)  goto throw_not_impl;
2375                        ek_opt = _adapter_opt_spread_ref;     break;
2376       default        : goto throw_not_impl;
2377       }
2378       assert(array_size == 0 ||  // it doesn't matter what the spreader is
2379              (ek_adapter_opt_spread_count(ek_opt) == -1 &&
2380               (ek_adapter_opt_spread_type(ek_opt) == dest ||
2381                (ek_adapter_opt_spread_type(ek_opt) == T_BYTE && dest == T_BOOLEAN))),
2382              err_msg("dest=%d ek_opt=%d", dest, ek_opt));
2383 
2384       if (array_size <= 0) {
2385         // since the general case does not handle length 0, this case is required:
2386         ek_opt = _adapter_opt_spread_0;
2387         break;
2388       }
2389       if (dest == T_OBJECT) {
2390         ek_try = EntryKind(_adapter_opt_spread_1_ref - 1 + array_size);
2391         if (ek_try < _adapter_opt_spread_LAST &&
2392             ek_adapter_opt_spread_count(ek_try) == array_size) {
2393           assert(ek_adapter_opt_spread_type(ek_try) == dest, "");
2394           ek_opt = ek_try;
2395           break;
2396         }
2397       }
2398       break;
2399     }
2400     break;
2401 
2402   case _adapter_collect_args:
2403     {
2404       assert(UseRicochetFrames, "else don't come here");
2405       int elem_slots = argument_slot_count(
2406                            java_lang_invoke_MethodHandle::type(
2407                                java_lang_invoke_AdapterMethodHandle::argument(mh()) ) );
2408       // vminfo will be the location to insert the return value
2409       vminfo = argslot;
2410       ensure_vmlayout_field(target, CHECK);
2411 
2412       // general case:
2413       switch (dest) {
2414       default       : if (!is_subword_type(dest))  goto throw_not_impl;
2415                     // else fall through:
2416       case T_INT    : ek_opt = _adapter_opt_collect_int;     break;
2417       case T_LONG   : ek_opt = _adapter_opt_collect_long;    break;
2418       case T_FLOAT  : ek_opt = _adapter_opt_collect_float;   break;
2419       case T_DOUBLE : ek_opt = _adapter_opt_collect_double;  break;
2420       case T_OBJECT : ek_opt = _adapter_opt_collect_ref;     break;
2421       case T_VOID   : ek_opt = _adapter_opt_collect_void;    break;
2422       }
2423       assert(ek_adapter_opt_collect_slot(ek_opt) == -1 &&
2424              ek_adapter_opt_collect_count(ek_opt) == -1 &&
2425              (ek_adapter_opt_collect_type(ek_opt) == dest ||
2426               ek_adapter_opt_collect_type(ek_opt) == T_INT && is_subword_type(dest)),
2427              "");
2428 
2429       if (dest == T_OBJECT && elem_slots == 1 && OptimizeMethodHandles) {
2430         // filter operation on a ref
2431         ek_try = EntryKind(_adapter_opt_filter_S0_ref + argslot);
2432         if (ek_try < _adapter_opt_collect_LAST &&
2433             ek_adapter_opt_collect_slot(ek_try) == argslot) {
2434           assert(ek_adapter_opt_collect_count(ek_try) == elem_slots &&
2435                  ek_adapter_opt_collect_type(ek_try) == dest, "");
2436           ek_opt = ek_try;
2437           break;
2438         }
2439         ek_opt = _adapter_opt_collect_1_ref;
2440         break;
2441       }
2442 
2443       if (dest == T_OBJECT && elem_slots == 2 && OptimizeMethodHandles) {
2444         // filter of two arguments
2445         ek_try = EntryKind(_adapter_opt_collect_2_S0_ref + argslot);
2446         if (ek_try < _adapter_opt_collect_LAST &&
2447             ek_adapter_opt_collect_slot(ek_try) == argslot) {
2448           assert(ek_adapter_opt_collect_count(ek_try) == elem_slots &&
2449                  ek_adapter_opt_collect_type(ek_try) == dest, "");
2450           ek_opt = ek_try;
2451           break;
2452         }
2453         ek_opt = _adapter_opt_collect_2_ref;
2454         break;
2455       }
2456 
2457       if (dest == T_OBJECT && OptimizeMethodHandles) {
2458         // try to use a fixed length adapter
2459         ek_try = EntryKind(_adapter_opt_collect_0_ref + elem_slots);
2460         if (ek_try < _adapter_opt_collect_LAST &&
2461             ek_adapter_opt_collect_count(ek_try) == elem_slots) {
2462           assert(ek_adapter_opt_collect_slot(ek_try) == -1 &&
2463                  ek_adapter_opt_collect_type(ek_try) == dest, "");
2464           ek_opt = ek_try;
2465           break;
2466         }
2467       }
2468 
2469       break;
2470     }
2471 
2472   case _adapter_fold_args:
2473     {
2474       assert(UseRicochetFrames, "else don't come here");
2475       int elem_slots = argument_slot_count(
2476                            java_lang_invoke_MethodHandle::type(
2477                                java_lang_invoke_AdapterMethodHandle::argument(mh()) ) );
2478       // vminfo will be the location to insert the return value
2479       vminfo = argslot + elem_slots;
2480       ensure_vmlayout_field(target, CHECK);
2481 
2482       switch (dest) {
2483       default       : if (!is_subword_type(dest))  goto throw_not_impl;
2484                     // else fall through:
2485       case T_INT    : ek_opt = _adapter_opt_fold_int;     break;
2486       case T_LONG   : ek_opt = _adapter_opt_fold_long;    break;
2487       case T_FLOAT  : ek_opt = _adapter_opt_fold_float;   break;
2488       case T_DOUBLE : ek_opt = _adapter_opt_fold_double;  break;
2489       case T_OBJECT : ek_opt = _adapter_opt_fold_ref;     break;
2490       case T_VOID   : ek_opt = _adapter_opt_fold_void;    break;
2491       }
2492       assert(ek_adapter_opt_collect_slot(ek_opt) == -1 &&
2493              ek_adapter_opt_collect_count(ek_opt) == -1 &&
2494              (ek_adapter_opt_collect_type(ek_opt) == dest ||
2495               ek_adapter_opt_collect_type(ek_opt) == T_INT && is_subword_type(dest)),
2496              "");
2497 
2498       if (dest == T_OBJECT && elem_slots == 0 && OptimizeMethodHandles) {
2499         // if there are no args, just pretend it's a collect
2500         ek_opt = _adapter_opt_collect_0_ref;
2501         break;
2502       }
2503 
2504       if (dest == T_OBJECT && OptimizeMethodHandles) {
2505         // try to use a fixed length adapter
2506         ek_try = EntryKind(_adapter_opt_fold_1_ref - 1 + elem_slots);
2507         if (ek_try < _adapter_opt_fold_LAST &&
2508             ek_adapter_opt_collect_count(ek_try) == elem_slots) {
2509           assert(ek_adapter_opt_collect_slot(ek_try) == -1 &&
2510                  ek_adapter_opt_collect_type(ek_try) == dest, "");
2511           ek_opt = ek_try;
2512           break;
2513         }
2514       }
2515 
2516       break;
2517     }
2518 
2519   default:
2520     // should have failed much earlier; must be a missing case here
2521     assert(false, "incomplete switch");
2522     // and fall through:
2523 
2524   throw_not_impl:
2525     if (err == NULL)
2526       err = "unknown adapter type";
2527     break;
2528   }
2529 
2530   if (err != NULL && (vminfo & CONV_VMINFO_MASK) != vminfo) {
2531     // should not happen, since vminfo is used to encode arg/slot indexes < 255
2532     err = "vminfo overflow";
2533   }
2534 
2535   if (err != NULL && !have_entry(ek_opt)) {
2536     err = "adapter stub for this kind of method handle is missing";
2537   }
2538 
2539   if (err != NULL) {
2540     throw_InternalError_for_bad_conversion(conversion, err, THREAD);
2541     return;
2542   }
2543 
2544   // Rebuild the conversion value; maybe parts of it were changed.
2545   jint new_conversion = adapter_conversion(conv_op, src, dest, stack_move, vminfo);
2546 
2547   // Finalize the conversion field.  (Note that it is final to Java code.)
2548   java_lang_invoke_AdapterMethodHandle::set_conversion(mh(), new_conversion);
2549 
2550   // Done!
2551   java_lang_invoke_MethodHandle::set_vmentry(mh(), entry(ek_opt));
2552 
2553   // There should be enough memory barriers on exit from native methods
2554   // to ensure that the MH is fully initialized to all threads before
2555   // Java code can publish it in global data structures.
2556 }
2557 
2558 void MethodHandles::ensure_vmlayout_field(Handle target, TRAPS) {
2559   Handle mtype(THREAD, java_lang_invoke_MethodHandle::type(target()));
2560   Handle mtform(THREAD, java_lang_invoke_MethodType::form(mtype()));
2561   if (mtform.is_null()) { THROW(vmSymbols::java_lang_InternalError()); }
2562   if (java_lang_invoke_MethodTypeForm::vmlayout_offset_in_bytes() > 0) {
2563     if (java_lang_invoke_MethodTypeForm::vmlayout(mtform()) == NULL) {
2564       // fill it in
2565       Handle erased_mtype(THREAD, java_lang_invoke_MethodTypeForm::erasedType(mtform()));
2566       TempNewSymbol erased_signature
2567         = java_lang_invoke_MethodType::as_signature(erased_mtype(), /*intern:*/true, CHECK);
2568       methodOop cookie
2569         = SystemDictionary::find_method_handle_invoke(vmSymbols::invokeExact_name(),
2570                                                       erased_signature,
2571                                                       SystemDictionaryHandles::Object_klass(),
2572                                                       THREAD);
2573       java_lang_invoke_MethodTypeForm::init_vmlayout(mtform(), cookie);
2574     }
2575   }
2576 }
2577 
2578 //
2579 // Here are the native methods on sun.invoke.MethodHandleImpl.
2580 // They are the private interface between this JVM and the HotSpot-specific
2581 // Java code that implements JSR 292 method handles.
2582 //
2583 // Note:  We use a JVM_ENTRY macro to define each of these, for this is the way
2584 // that intrinsic (non-JNI) native methods are defined in HotSpot.
2585 //
2586 
2587 // direct method handles for invokestatic or invokespecial
2588 // void init(DirectMethodHandle self, MemberName ref, boolean doDispatch, Class<?> caller);
2589 JVM_ENTRY(void, MHN_init_DMH(JNIEnv *env, jobject igcls, jobject mh_jh,
2590                              jobject target_jh, jboolean do_dispatch, jobject caller_jh)) {
2591   ResourceMark rm;              // for error messages
2592 
2593   // This is the guy we are initializing:
2594   if (mh_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
2595   Handle mh(THREAD, JNIHandles::resolve_non_null(mh_jh));
2596 
2597   // Early returns out of this method leave the DMH in an unfinished state.
2598   assert(java_lang_invoke_MethodHandle::vmentry(mh()) == NULL, "must be safely null");
2599 
2600   // which method are we really talking about?
2601   if (target_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
2602   Handle target(THREAD, JNIHandles::resolve_non_null(target_jh));
2603   if (java_lang_invoke_MemberName::is_instance(target()) &&
2604       java_lang_invoke_MemberName::vmindex(target()) == VM_INDEX_UNINITIALIZED) {
2605     MethodHandles::resolve_MemberName(target, CHECK);
2606   }
2607 
2608   KlassHandle receiver_limit; int decode_flags = 0;
2609   methodHandle m = MethodHandles::decode_method(target(), receiver_limit, decode_flags);
2610   if (m.is_null()) { THROW_MSG(vmSymbols::java_lang_InternalError(), "no such method"); }
2611 
2612   // The trusted Java code that calls this method should already have performed
2613   // access checks on behalf of the given caller.  But, we can verify this.
2614   if (VerifyMethodHandles && caller_jh != NULL) {
2615     KlassHandle caller(THREAD, java_lang_Class::as_klassOop(JNIHandles::resolve_non_null(caller_jh)));
2616     // If this were a bytecode, the first access check would be against
2617     // the "reference class" mentioned in the CONSTANT_Methodref.
2618     // We don't know at this point which class that was, and if we
2619     // check against m.method_holder we might get the wrong answer.
2620     // So we just make sure to handle this check when the resolution
2621     // happens, when we call resolve_MemberName.
2622     //
2623     // (A public class can inherit public members from private supers,
2624     // and it would be wrong to check access against the private super
2625     // if the original symbolic reference was against the public class.)
2626     //
2627     // If there were a bytecode, the next step would be to lookup the method
2628     // in the reference class, then then check the method's access bits.
2629     // Emulate LinkResolver::check_method_accessability.
2630     klassOop resolved_klass = m->method_holder();
2631     if (!Reflection::verify_field_access(caller->as_klassOop(),
2632                                          resolved_klass, resolved_klass,
2633                                          m->access_flags(),
2634                                          true)) {
2635       // %%% following cutout belongs in Reflection::verify_field_access?
2636       bool same_pm = Reflection::is_same_package_member(caller->as_klassOop(),
2637                                                         resolved_klass, THREAD);
2638       if (!same_pm) {
2639         THROW_MSG(vmSymbols::java_lang_InternalError(), m->name_and_sig_as_C_string());
2640       }
2641     }
2642   }
2643 
2644   MethodHandles::init_DirectMethodHandle(mh, m, (do_dispatch != JNI_FALSE), CHECK);
2645 }
2646 JVM_END
2647 
2648 // bound method handles
2649 JVM_ENTRY(void, MHN_init_BMH(JNIEnv *env, jobject igcls, jobject mh_jh,
2650                              jobject target_jh, int argnum)) {
2651   ResourceMark rm;              // for error messages
2652 
2653   // This is the guy we are initializing:
2654   if (mh_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
2655   Handle mh(THREAD, JNIHandles::resolve_non_null(mh_jh));
2656 
2657   // Early returns out of this method leave the BMH in an unfinished state.
2658   assert(java_lang_invoke_MethodHandle::vmentry(mh()) == NULL, "must be safely null");
2659 
2660   if (target_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
2661   Handle target(THREAD, JNIHandles::resolve_non_null(target_jh));
2662 
2663   if (!java_lang_invoke_MethodHandle::is_instance(target())) {
2664     // Target object is a reflective method.  (%%% Do we need this alternate path?)
2665     Untested("init_BMH of non-MH");
2666     if (argnum != 0) { THROW(vmSymbols::java_lang_InternalError()); }
2667     KlassHandle receiver_limit; int decode_flags = 0;
2668     methodHandle m = MethodHandles::decode_method(target(), receiver_limit, decode_flags);
2669     MethodHandles::init_BoundMethodHandle_with_receiver(mh, m,
2670                                                        receiver_limit,
2671                                                        decode_flags,
2672                                                        CHECK);
2673     return;
2674   }
2675 
2676   // Build a BMH on top of a DMH or another BMH:
2677   MethodHandles::init_BoundMethodHandle(mh, target, argnum, CHECK);
2678 }
2679 JVM_END
2680 
2681 // adapter method handles
2682 JVM_ENTRY(void, MHN_init_AMH(JNIEnv *env, jobject igcls, jobject mh_jh,
2683                              jobject target_jh, int argnum)) {
2684   // This is the guy we are initializing:
2685   if (mh_jh == NULL || target_jh == NULL) {
2686     THROW(vmSymbols::java_lang_InternalError());
2687   }
2688   Handle mh(THREAD, JNIHandles::resolve_non_null(mh_jh));
2689   Handle target(THREAD, JNIHandles::resolve_non_null(target_jh));
2690 
2691   // Early returns out of this method leave the AMH in an unfinished state.
2692   assert(java_lang_invoke_MethodHandle::vmentry(mh()) == NULL, "must be safely null");
2693 
2694   MethodHandles::init_AdapterMethodHandle(mh, target, argnum, CHECK);
2695 }
2696 JVM_END
2697 
2698 // method type forms
2699 JVM_ENTRY(void, MHN_init_MT(JNIEnv *env, jobject igcls, jobject erased_jh)) {
2700   if (erased_jh == NULL)  return;
2701   if (TraceMethodHandles) {
2702     tty->print("creating MethodType form ");
2703     if (WizardMode || Verbose) {   // Warning: this calls Java code on the MH!
2704       // call Object.toString()
2705       Symbol* name = vmSymbols::toString_name();
2706       Symbol* sig = vmSymbols::void_string_signature();
2707       JavaCallArguments args(Handle(THREAD, JNIHandles::resolve_non_null(erased_jh)));
2708       JavaValue result(T_OBJECT);
2709       JavaCalls::call_virtual(&result, SystemDictionary::Object_klass(), name, sig,
2710                               &args, CHECK);
2711       Handle str(THREAD, (oop)result.get_jobject());
2712       java_lang_String::print(str, tty);
2713     }
2714     tty->cr();
2715   }
2716 }
2717 JVM_END
2718 
2719 // debugging and reflection
2720 JVM_ENTRY(jobject, MHN_getTarget(JNIEnv *env, jobject igcls, jobject mh_jh, jint format)) {
2721   Handle mh(THREAD, JNIHandles::resolve(mh_jh));
2722   if (!java_lang_invoke_MethodHandle::is_instance(mh())) {
2723     THROW_NULL(vmSymbols::java_lang_IllegalArgumentException());
2724   }
2725   oop target = MethodHandles::encode_target(mh, format, CHECK_NULL);
2726   return JNIHandles::make_local(THREAD, target);
2727 }
2728 JVM_END
2729 
2730 JVM_ENTRY(jint, MHN_getConstant(JNIEnv *env, jobject igcls, jint which)) {
2731   switch (which) {
2732   case MethodHandles::GC_JVM_PUSH_LIMIT:
2733     guarantee(MethodHandlePushLimit >= 2 && MethodHandlePushLimit <= 0xFF,
2734               "MethodHandlePushLimit parameter must be in valid range");
2735     return MethodHandlePushLimit;
2736   case MethodHandles::GC_JVM_STACK_MOVE_UNIT:
2737     // return number of words per slot, signed according to stack direction
2738     return MethodHandles::stack_move_unit();
2739   case MethodHandles::GC_CONV_OP_IMPLEMENTED_MASK:
2740     return MethodHandles::adapter_conversion_ops_supported_mask();
2741   }
2742   return 0;
2743 }
2744 JVM_END
2745 
2746 #ifndef PRODUCT
2747 #define EACH_NAMED_CON(template) \
2748   /* hold back this one until JDK stabilizes */ \
2749   /* template(MethodHandles,GC_JVM_PUSH_LIMIT) */  \
2750   /* hold back this one until JDK stabilizes */ \
2751   /* template(MethodHandles,GC_JVM_STACK_MOVE_UNIT) */ \
2752     template(MethodHandles,ETF_HANDLE_OR_METHOD_NAME) \
2753     template(MethodHandles,ETF_DIRECT_HANDLE) \
2754     template(MethodHandles,ETF_METHOD_NAME) \
2755     template(MethodHandles,ETF_REFLECT_METHOD) \
2756     template(java_lang_invoke_MemberName,MN_IS_METHOD) \
2757     template(java_lang_invoke_MemberName,MN_IS_CONSTRUCTOR) \
2758     template(java_lang_invoke_MemberName,MN_IS_FIELD) \
2759     template(java_lang_invoke_MemberName,MN_IS_TYPE) \
2760     template(java_lang_invoke_MemberName,MN_SEARCH_SUPERCLASSES) \
2761     template(java_lang_invoke_MemberName,MN_SEARCH_INTERFACES) \
2762     template(java_lang_invoke_MemberName,VM_INDEX_UNINITIALIZED) \
2763     template(java_lang_invoke_AdapterMethodHandle,OP_RETYPE_ONLY) \
2764     template(java_lang_invoke_AdapterMethodHandle,OP_RETYPE_RAW) \
2765     template(java_lang_invoke_AdapterMethodHandle,OP_CHECK_CAST) \
2766     template(java_lang_invoke_AdapterMethodHandle,OP_PRIM_TO_PRIM) \
2767     template(java_lang_invoke_AdapterMethodHandle,OP_REF_TO_PRIM) \
2768     template(java_lang_invoke_AdapterMethodHandle,OP_PRIM_TO_REF) \
2769     template(java_lang_invoke_AdapterMethodHandle,OP_SWAP_ARGS) \
2770     template(java_lang_invoke_AdapterMethodHandle,OP_ROT_ARGS) \
2771     template(java_lang_invoke_AdapterMethodHandle,OP_DUP_ARGS) \
2772     template(java_lang_invoke_AdapterMethodHandle,OP_DROP_ARGS) \
2773     template(java_lang_invoke_AdapterMethodHandle,OP_COLLECT_ARGS) \
2774     template(java_lang_invoke_AdapterMethodHandle,OP_SPREAD_ARGS) \
2775       /* hold back this one until JDK stabilizes */ \
2776       /*template(java_lang_invoke_AdapterMethodHandle,CONV_OP_LIMIT)*/  \
2777     template(java_lang_invoke_AdapterMethodHandle,CONV_OP_MASK) \
2778     template(java_lang_invoke_AdapterMethodHandle,CONV_VMINFO_MASK) \
2779     template(java_lang_invoke_AdapterMethodHandle,CONV_VMINFO_SHIFT) \
2780     template(java_lang_invoke_AdapterMethodHandle,CONV_OP_SHIFT) \
2781     template(java_lang_invoke_AdapterMethodHandle,CONV_DEST_TYPE_SHIFT) \
2782     template(java_lang_invoke_AdapterMethodHandle,CONV_SRC_TYPE_SHIFT) \
2783     template(java_lang_invoke_AdapterMethodHandle,CONV_STACK_MOVE_SHIFT) \
2784     template(java_lang_invoke_AdapterMethodHandle,CONV_STACK_MOVE_MASK) \
2785     /*end*/
2786 
2787 #define ONE_PLUS(scope,value) 1+
2788 static const int con_value_count = EACH_NAMED_CON(ONE_PLUS) 0;
2789 #define VALUE_COMMA(scope,value) scope::value,
2790 static const int con_values[con_value_count+1] = { EACH_NAMED_CON(VALUE_COMMA) 0 };
2791 #define STRING_NULL(scope,value) #value "\0"
2792 static const char con_names[] = { EACH_NAMED_CON(STRING_NULL) };
2793 
2794 #undef ONE_PLUS
2795 #undef VALUE_COMMA
2796 #undef STRING_NULL
2797 #undef EACH_NAMED_CON
2798 #endif
2799 
2800 JVM_ENTRY(jint, MHN_getNamedCon(JNIEnv *env, jobject igcls, jint which, jobjectArray box_jh)) {
2801 #ifndef PRODUCT
2802   if (which >= 0 && which < con_value_count) {
2803     int con = con_values[which];
2804     objArrayHandle box(THREAD, (objArrayOop) JNIHandles::resolve(box_jh));
2805     if (box.not_null() && box->klass() == Universe::objectArrayKlassObj() && box->length() > 0) {
2806       const char* str = &con_names[0];
2807       for (int i = 0; i < which; i++)
2808         str += strlen(str) + 1;   // skip name and null
2809       oop name = java_lang_String::create_oop_from_str(str, CHECK_0);  // possible safepoint
2810       box->obj_at_put(0, name);
2811     }
2812     return con;
2813   }
2814 #endif
2815   return 0;
2816 }
2817 JVM_END
2818 
2819 // void init(MemberName self, AccessibleObject ref)
2820 JVM_ENTRY(void, MHN_init_Mem(JNIEnv *env, jobject igcls, jobject mname_jh, jobject target_jh)) {
2821   if (mname_jh == NULL || target_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
2822   Handle mname(THREAD, JNIHandles::resolve_non_null(mname_jh));
2823   oop target_oop = JNIHandles::resolve_non_null(target_jh);
2824   MethodHandles::init_MemberName(mname(), target_oop);
2825 }
2826 JVM_END
2827 
2828 // void expand(MemberName self)
2829 JVM_ENTRY(void, MHN_expand_Mem(JNIEnv *env, jobject igcls, jobject mname_jh)) {
2830   if (mname_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
2831   Handle mname(THREAD, JNIHandles::resolve_non_null(mname_jh));
2832   MethodHandles::expand_MemberName(mname, 0, CHECK);
2833 }
2834 JVM_END
2835 
2836 // void resolve(MemberName self, Class<?> caller)
2837 JVM_ENTRY(void, MHN_resolve_Mem(JNIEnv *env, jobject igcls, jobject mname_jh, jclass caller_jh)) {
2838   if (mname_jh == NULL) { THROW(vmSymbols::java_lang_InternalError()); }
2839   Handle mname(THREAD, JNIHandles::resolve_non_null(mname_jh));
2840 
2841   // The trusted Java code that calls this method should already have performed
2842   // access checks on behalf of the given caller.  But, we can verify this.
2843   if (VerifyMethodHandles && caller_jh != NULL) {
2844     klassOop reference_klass = java_lang_Class::as_klassOop(java_lang_invoke_MemberName::clazz(mname()));
2845     if (reference_klass != NULL) {
2846       // Emulate LinkResolver::check_klass_accessability.
2847       klassOop caller = java_lang_Class::as_klassOop(JNIHandles::resolve_non_null(caller_jh));
2848       if (!Reflection::verify_class_access(caller,
2849                                            reference_klass,
2850                                            true)) {
2851         THROW_MSG(vmSymbols::java_lang_InternalError(), Klass::cast(reference_klass)->external_name());
2852       }
2853     }
2854   }
2855 
2856   MethodHandles::resolve_MemberName(mname, CHECK);
2857 }
2858 JVM_END
2859 
2860 //  static native int getMembers(Class<?> defc, String matchName, String matchSig,
2861 //          int matchFlags, Class<?> caller, int skip, MemberName[] results);
2862 JVM_ENTRY(jint, MHN_getMembers(JNIEnv *env, jobject igcls,
2863                                jclass clazz_jh, jstring name_jh, jstring sig_jh,
2864                                int mflags, jclass caller_jh, jint skip, jobjectArray results_jh)) {
2865   if (clazz_jh == NULL || results_jh == NULL)  return -1;
2866   KlassHandle k(THREAD, java_lang_Class::as_klassOop(JNIHandles::resolve_non_null(clazz_jh)));
2867 
2868   objArrayHandle results(THREAD, (objArrayOop) JNIHandles::resolve(results_jh));
2869   if (results.is_null() || !results->is_objArray())  return -1;
2870 
2871   TempNewSymbol name = NULL;
2872   TempNewSymbol sig = NULL;
2873   if (name_jh != NULL) {
2874     name = java_lang_String::as_symbol_or_null(JNIHandles::resolve_non_null(name_jh));
2875     if (name == NULL)  return 0; // a match is not possible
2876   }
2877   if (sig_jh != NULL) {
2878     sig = java_lang_String::as_symbol_or_null(JNIHandles::resolve_non_null(sig_jh));
2879     if (sig == NULL)  return 0; // a match is not possible
2880   }
2881 
2882   KlassHandle caller;
2883   if (caller_jh != NULL) {
2884     oop caller_oop = JNIHandles::resolve_non_null(caller_jh);
2885     if (!java_lang_Class::is_instance(caller_oop))  return -1;
2886     caller = KlassHandle(THREAD, java_lang_Class::as_klassOop(caller_oop));
2887   }
2888 
2889   if (name != NULL && sig != NULL && results.not_null()) {
2890     // try a direct resolve
2891     // %%% TO DO
2892   }
2893 
2894   int res = MethodHandles::find_MemberNames(k(), name, sig, mflags,
2895                                             caller(), skip, results());
2896   // TO DO: expand at least some of the MemberNames, to avoid massive callbacks
2897   return res;
2898 }
2899 JVM_END
2900 
2901 
2902 /// JVM_RegisterMethodHandleMethods
2903 
2904 #define LANG "Ljava/lang/"
2905 #define JLINV "Ljava/lang/invoke/"
2906 
2907 #define OBJ   LANG"Object;"
2908 #define CLS   LANG"Class;"
2909 #define STRG  LANG"String;"
2910 #define MT    JLINV"MethodType;"
2911 #define MH    JLINV"MethodHandle;"
2912 #define MEM   JLINV"MemberName;"
2913 #define AMH   JLINV"AdapterMethodHandle;"
2914 #define BMH   JLINV"BoundMethodHandle;"
2915 #define DMH   JLINV"DirectMethodHandle;"
2916 
2917 #define CC (char*)  /*cast a literal from (const char*)*/
2918 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
2919 
2920 // These are the native methods on sun.invoke.MethodHandleNatives.
2921 static JNINativeMethod methods[] = {
2922   // void init(MemberName self, AccessibleObject ref)
2923   {CC"init",                    CC"("AMH""MH"I)V",              FN_PTR(MHN_init_AMH)},
2924   {CC"init",                    CC"("BMH""OBJ"I)V",             FN_PTR(MHN_init_BMH)},
2925   {CC"init",                    CC"("DMH""OBJ"Z"CLS")V",        FN_PTR(MHN_init_DMH)},
2926   {CC"init",                    CC"("MT")V",                    FN_PTR(MHN_init_MT)},
2927   {CC"init",                    CC"("MEM""OBJ")V",              FN_PTR(MHN_init_Mem)},
2928   {CC"expand",                  CC"("MEM")V",                   FN_PTR(MHN_expand_Mem)},
2929   {CC"resolve",                 CC"("MEM""CLS")V",              FN_PTR(MHN_resolve_Mem)},
2930   {CC"getTarget",               CC"("MH"I)"OBJ,                 FN_PTR(MHN_getTarget)},
2931   {CC"getConstant",             CC"(I)I",                       FN_PTR(MHN_getConstant)},
2932   //  static native int getNamedCon(int which, Object[] name)
2933   {CC"getNamedCon",             CC"(I["OBJ")I",                 FN_PTR(MHN_getNamedCon)},
2934   //  static native int getMembers(Class<?> defc, String matchName, String matchSig,
2935   //          int matchFlags, Class<?> caller, int skip, MemberName[] results);
2936   {CC"getMembers",              CC"("CLS""STRG""STRG"I"CLS"I["MEM")I",  FN_PTR(MHN_getMembers)}
2937 };
2938 
2939 // This one function is exported, used by NativeLookup.
2940 
2941 JVM_ENTRY(void, JVM_RegisterMethodHandleMethods(JNIEnv *env, jclass MHN_class)) {
2942   assert(MethodHandles::spot_check_entry_names(), "entry enum is OK");
2943 
2944   if (!EnableInvokeDynamic) {
2945     warning("JSR 292 is disabled in this JVM.  Use -XX:+UnlockDiagnosticVMOptions -XX:+EnableInvokeDynamic to enable.");
2946     return;  // bind nothing
2947   }
2948 
2949   bool enable_MH = true;
2950 
2951   {
2952     ThreadToNativeFromVM ttnfv(thread);
2953 
2954     int status = env->RegisterNatives(MHN_class, methods, sizeof(methods)/sizeof(JNINativeMethod));
2955     if (env->ExceptionOccurred()) {
2956       MethodHandles::set_enabled(false);
2957       warning("JSR 292 method handle code is mismatched to this JVM.  Disabling support.");
2958       enable_MH = false;
2959       env->ExceptionClear();
2960     }
2961   }
2962 
2963   if (enable_MH) {
2964     KlassHandle MHN_klass = SystemDictionaryHandles::MethodHandleNatives_klass();
2965     if (MHN_klass.not_null()) {
2966       TempNewSymbol raiseException_name = SymbolTable::new_symbol("raiseException", CHECK);
2967       TempNewSymbol raiseException_sig = SymbolTable::new_symbol("(ILjava/lang/Object;Ljava/lang/Object;)V", CHECK);
2968       methodOop raiseException_method  = instanceKlass::cast(MHN_klass->as_klassOop())
2969                     ->find_method(raiseException_name, raiseException_sig);
2970       if (raiseException_method != NULL && raiseException_method->is_static()) {
2971         MethodHandles::set_raise_exception_method(raiseException_method);
2972       } else {
2973         warning("JSR 292 method handle code is mismatched to this JVM.  Disabling support.");
2974         enable_MH = false;
2975       }
2976     } else {
2977       enable_MH = false;
2978     }
2979   }
2980 
2981   if (enable_MH) {
2982     MethodHandles::generate_adapters();
2983     MethodHandles::set_enabled(true);
2984   }
2985 }
2986 JVM_END