1 /*
   2  * Copyright (c) 1997, 2018, 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 "jvm.h"
  27 #include "asm/macroAssembler.hpp"
  28 #include "classfile/javaClasses.inline.hpp"
  29 #include "interpreter/interpreter.hpp"
  30 #include "interpreter/interpreterRuntime.hpp"
  31 #include "memory/allocation.inline.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "prims/methodHandles.hpp"
  34 #include "runtime/flags/flagSetting.hpp"
  35 #include "runtime/frame.inline.hpp"
  36 #include "utilities/preserveException.hpp"
  37 
  38 #define __ _masm->
  39 
  40 #ifdef PRODUCT
  41 #define BLOCK_COMMENT(str) /* nothing */
  42 #define STOP(error) stop(error)
  43 #else
  44 #define BLOCK_COMMENT(str) __ block_comment(str)
  45 #define STOP(error) block_comment(error); __ stop(error)
  46 #endif
  47 
  48 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")
  49 
  50 void MethodHandles::load_klass_from_Class(MacroAssembler* _masm, Register klass_reg) {
  51   if (VerifyMethodHandles)
  52     verify_klass(_masm, klass_reg, SystemDictionary::WK_KLASS_ENUM_NAME(java_lang_Class),
  53                  "MH argument is a Class");
  54   __ movptr(klass_reg, Address(klass_reg, java_lang_Class::klass_offset_in_bytes()));
  55 }
  56 
  57 #ifdef ASSERT
  58 static int check_nonzero(const char* xname, int x) {
  59   assert(x != 0, "%s should be nonzero", xname);
  60   return x;
  61 }
  62 #define NONZERO(x) check_nonzero(#x, x)
  63 #else //ASSERT
  64 #define NONZERO(x) (x)
  65 #endif //ASSERT
  66 
  67 #ifdef ASSERT
  68 void MethodHandles::verify_klass(MacroAssembler* _masm,
  69                                  Register obj, SystemDictionary::WKID klass_id,
  70                                  const char* error_message) {
  71   InstanceKlass** klass_addr = SystemDictionary::well_known_klass_addr(klass_id);
  72   Klass* klass = SystemDictionary::well_known_klass(klass_id);
  73   Register temp = rdi;
  74   Register temp2 = noreg;
  75   LP64_ONLY(temp2 = rscratch1);  // used by MacroAssembler::cmpptr
  76   Label L_ok, L_bad;
  77   BLOCK_COMMENT("verify_klass {");
  78   __ verify_oop(obj);
  79   __ testptr(obj, obj);
  80   __ jcc(Assembler::zero, L_bad);
  81   __ push(temp); if (temp2 != noreg)  __ push(temp2);
  82 #define UNPUSH { if (temp2 != noreg)  __ pop(temp2);  __ pop(temp); }
  83   __ load_klass(temp, obj);
  84   __ cmpptr(temp, ExternalAddress((address) klass_addr));
  85   __ jcc(Assembler::equal, L_ok);
  86   intptr_t super_check_offset = klass->super_check_offset();
  87   __ movptr(temp, Address(temp, super_check_offset));
  88   __ cmpptr(temp, ExternalAddress((address) klass_addr));
  89   __ jcc(Assembler::equal, L_ok);
  90   UNPUSH;
  91   __ bind(L_bad);
  92   __ STOP(error_message);
  93   __ BIND(L_ok);
  94   UNPUSH;
  95   BLOCK_COMMENT("} verify_klass");
  96 }
  97 
  98 void MethodHandles::verify_ref_kind(MacroAssembler* _masm, int ref_kind, Register member_reg, Register temp) {
  99   Label L;
 100   BLOCK_COMMENT("verify_ref_kind {");
 101   __ movl(temp, Address(member_reg, NONZERO(java_lang_invoke_MemberName::flags_offset_in_bytes())));
 102   __ shrl(temp, java_lang_invoke_MemberName::MN_REFERENCE_KIND_SHIFT);
 103   __ andl(temp, java_lang_invoke_MemberName::MN_REFERENCE_KIND_MASK);
 104   __ cmpl(temp, ref_kind);
 105   __ jcc(Assembler::equal, L);
 106   { char* buf = NEW_C_HEAP_ARRAY(char, 100, mtInternal);
 107     jio_snprintf(buf, 100, "verify_ref_kind expected %x", ref_kind);
 108     if (ref_kind == JVM_REF_invokeVirtual ||
 109         ref_kind == JVM_REF_invokeSpecial)
 110       // could do this for all ref_kinds, but would explode assembly code size
 111       trace_method_handle(_masm, buf);
 112     __ STOP(buf);
 113   }
 114   BLOCK_COMMENT("} verify_ref_kind");
 115   __ bind(L);
 116 }
 117 
 118 #endif //ASSERT
 119 
 120 void MethodHandles::jump_from_method_handle(MacroAssembler* _masm, Register method, Register temp,
 121                                             bool for_compiler_entry) {
 122   assert(method == rbx, "interpreter calling convention");
 123 
 124    Label L_no_such_method;
 125    __ testptr(rbx, rbx);
 126    __ jcc(Assembler::zero, L_no_such_method);
 127 
 128   __ verify_method_ptr(method);
 129 
 130   if (!for_compiler_entry && JvmtiExport::can_post_interpreter_events()) {
 131     Label run_compiled_code;
 132     // JVMTI events, such as single-stepping, are implemented partly by avoiding running
 133     // compiled code in threads for which the event is enabled.  Check here for
 134     // interp_only_mode if these events CAN be enabled.
 135 #ifdef _LP64
 136     Register rthread = r15_thread;
 137 #else
 138     Register rthread = temp;
 139     __ get_thread(rthread);
 140 #endif
 141     // interp_only is an int, on little endian it is sufficient to test the byte only
 142     // Is a cmpl faster?
 143     __ cmpb(Address(rthread, JavaThread::interp_only_mode_offset()), 0);
 144     __ jccb(Assembler::zero, run_compiled_code);
 145     __ jmp(Address(method, Method::interpreter_entry_offset()));
 146     __ BIND(run_compiled_code);
 147   }
 148 
 149   const ByteSize entry_offset = for_compiler_entry ? Method::from_compiled_offset() :
 150                                                      Method::from_interpreted_offset();
 151   __ jmp(Address(method, entry_offset));
 152 
 153   __ bind(L_no_such_method);
 154   __ jump(RuntimeAddress(StubRoutines::throw_AbstractMethodError_entry()));
 155 }
 156 
 157 void MethodHandles::jump_to_lambda_form(MacroAssembler* _masm,
 158                                         Register recv, Register method_temp,
 159                                         Register temp2,
 160                                         bool for_compiler_entry) {
 161   BLOCK_COMMENT("jump_to_lambda_form {");
 162   // This is the initial entry point of a lazy method handle.
 163   // After type checking, it picks up the invoker from the LambdaForm.
 164   assert_different_registers(recv, method_temp, temp2);
 165   assert(recv != noreg, "required register");
 166   assert(method_temp == rbx, "required register for loading method");
 167 
 168   //NOT_PRODUCT({ FlagSetting fs(TraceMethodHandles, true); trace_method_handle(_masm, "LZMH"); });
 169 
 170   // Load the invoker, as MH -> MH.form -> LF.vmentry
 171   __ verify_oop(recv);
 172   __ load_heap_oop(method_temp, Address(recv, NONZERO(java_lang_invoke_MethodHandle::form_offset_in_bytes())), temp2);
 173   __ verify_oop(method_temp);
 174   __ load_heap_oop(method_temp, Address(method_temp, NONZERO(java_lang_invoke_LambdaForm::vmentry_offset_in_bytes())), temp2);
 175   __ verify_oop(method_temp);
 176   __ load_heap_oop(method_temp, Address(method_temp, NONZERO(java_lang_invoke_MemberName::method_offset_in_bytes())), temp2);
 177   __ verify_oop(method_temp);
 178   __ movptr(method_temp, Address(method_temp, NONZERO(java_lang_invoke_ResolvedMethodName::vmtarget_offset_in_bytes())));
 179 
 180   if (VerifyMethodHandles && !for_compiler_entry) {
 181     // make sure recv is already on stack
 182     __ movptr(temp2, Address(method_temp, Method::const_offset()));
 183     __ load_sized_value(temp2,
 184                         Address(temp2, ConstMethod::size_of_parameters_offset()),
 185                         sizeof(u2), /*is_signed*/ false);
 186     // assert(sizeof(u2) == sizeof(Method::_size_of_parameters), "");
 187     Label L;
 188     __ cmpoop(recv, __ argument_address(temp2, -1));
 189     __ jcc(Assembler::equal, L);
 190     __ movptr(rax, __ argument_address(temp2, -1));
 191     __ STOP("receiver not on stack");
 192     __ BIND(L);
 193   }
 194 
 195   jump_from_method_handle(_masm, method_temp, temp2, for_compiler_entry);
 196   BLOCK_COMMENT("} jump_to_lambda_form");
 197 }
 198 
 199 
 200 // Code generation
 201 address MethodHandles::generate_method_handle_interpreter_entry(MacroAssembler* _masm,
 202                                                                 vmIntrinsics::ID iid) {
 203   const bool not_for_compiler_entry = false;  // this is the interpreter entry
 204   assert(is_signature_polymorphic(iid), "expected invoke iid");
 205   if (iid == vmIntrinsics::_invokeGeneric ||
 206       iid == vmIntrinsics::_compiledLambdaForm) {
 207     // Perhaps surprisingly, the symbolic references visible to Java are not directly used.
 208     // They are linked to Java-generated adapters via MethodHandleNatives.linkMethod.
 209     // They all allow an appendix argument.
 210     __ hlt();           // empty stubs make SG sick
 211     return NULL;
 212   }
 213 
 214   // rsi/r13: sender SP (must preserve; see prepare_to_jump_from_interpreted)
 215   // rbx: Method*
 216   // rdx: argument locator (parameter slot count, added to rsp)
 217   // rcx: used as temp to hold mh or receiver
 218   // rax, rdi: garbage temps, blown away
 219   Register rdx_argp   = rdx;   // argument list ptr, live on error paths
 220   Register rax_temp   = rax;
 221   Register rcx_mh     = rcx;   // MH receiver; dies quickly and is recycled
 222   Register rbx_method = rbx;   // eventual target of this invocation
 223 
 224   // here's where control starts out:
 225   __ align(CodeEntryAlignment);
 226   address entry_point = __ pc();
 227 
 228   if (VerifyMethodHandles) {
 229     assert(Method::intrinsic_id_size_in_bytes() == 2, "assuming Method::_intrinsic_id is u2");
 230 
 231     Label L;
 232     BLOCK_COMMENT("verify_intrinsic_id {");
 233     __ cmpw(Address(rbx_method, Method::intrinsic_id_offset_in_bytes()), (int) iid);
 234     __ jcc(Assembler::equal, L);
 235     if (iid == vmIntrinsics::_linkToVirtual ||
 236         iid == vmIntrinsics::_linkToSpecial) {
 237       // could do this for all kinds, but would explode assembly code size
 238       trace_method_handle(_masm, "bad Method*::intrinsic_id");
 239     }
 240     __ STOP("bad Method*::intrinsic_id");
 241     __ bind(L);
 242     BLOCK_COMMENT("} verify_intrinsic_id");
 243   }
 244 
 245   // First task:  Find out how big the argument list is.
 246   Address rdx_first_arg_addr;
 247   int ref_kind = signature_polymorphic_intrinsic_ref_kind(iid);
 248   assert(ref_kind != 0 || iid == vmIntrinsics::_invokeBasic, "must be _invokeBasic or a linkTo intrinsic");
 249   if (ref_kind == 0 || MethodHandles::ref_kind_has_receiver(ref_kind)) {
 250     __ movptr(rdx_argp, Address(rbx_method, Method::const_offset()));
 251     __ load_sized_value(rdx_argp,
 252                         Address(rdx_argp, ConstMethod::size_of_parameters_offset()),
 253                         sizeof(u2), /*is_signed*/ false);
 254     // assert(sizeof(u2) == sizeof(Method::_size_of_parameters), "");
 255     rdx_first_arg_addr = __ argument_address(rdx_argp, -1);
 256   } else {
 257     DEBUG_ONLY(rdx_argp = noreg);
 258   }
 259 
 260   if (!is_signature_polymorphic_static(iid)) {
 261     __ movptr(rcx_mh, rdx_first_arg_addr);
 262     DEBUG_ONLY(rdx_argp = noreg);
 263   }
 264 
 265   // rdx_first_arg_addr is live!
 266 
 267   trace_method_handle_interpreter_entry(_masm, iid);
 268 
 269   if (iid == vmIntrinsics::_invokeBasic) {
 270     generate_method_handle_dispatch(_masm, iid, rcx_mh, noreg, not_for_compiler_entry);
 271 
 272   } else {
 273     // Adjust argument list by popping the trailing MemberName argument.
 274     Register rcx_recv = noreg;
 275     if (MethodHandles::ref_kind_has_receiver(ref_kind)) {
 276       // Load the receiver (not the MH; the actual MemberName's receiver) up from the interpreter stack.
 277       __ movptr(rcx_recv = rcx, rdx_first_arg_addr);
 278     }
 279     DEBUG_ONLY(rdx_argp = noreg);
 280     Register rbx_member = rbx_method;  // MemberName ptr; incoming method ptr is dead now
 281     __ pop(rax_temp);           // return address
 282     __ pop(rbx_member);         // extract last argument
 283     __ push(rax_temp);          // re-push return address
 284     generate_method_handle_dispatch(_masm, iid, rcx_recv, rbx_member, not_for_compiler_entry);
 285   }
 286 
 287   return entry_point;
 288 }
 289 
 290 void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
 291                                                     vmIntrinsics::ID iid,
 292                                                     Register receiver_reg,
 293                                                     Register member_reg,
 294                                                     bool for_compiler_entry) {
 295   assert(is_signature_polymorphic(iid), "expected invoke iid");
 296   Register rbx_method = rbx;   // eventual target of this invocation
 297   // temps used in this code are not used in *either* compiled or interpreted calling sequences
 298 #ifdef _LP64
 299   Register temp1 = rscratch1;
 300   Register temp2 = rscratch2;
 301   Register temp3 = rax;
 302   if (for_compiler_entry) {
 303     assert(receiver_reg == (iid == vmIntrinsics::_linkToStatic ? noreg : j_rarg0), "only valid assignment");
 304     assert_different_registers(temp1,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5);
 305     assert_different_registers(temp2,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5);
 306     assert_different_registers(temp3,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5);
 307   }
 308 #else
 309   Register temp1 = (for_compiler_entry ? rsi : rdx);
 310   Register temp2 = rdi;
 311   Register temp3 = rax;
 312   if (for_compiler_entry) {
 313     assert(receiver_reg == (iid == vmIntrinsics::_linkToStatic ? noreg : rcx), "only valid assignment");
 314     assert_different_registers(temp1,        rcx, rdx);
 315     assert_different_registers(temp2,        rcx, rdx);
 316     assert_different_registers(temp3,        rcx, rdx);
 317   }
 318 #endif
 319   else {
 320     assert_different_registers(temp1, temp2, temp3, saved_last_sp_register());  // don't trash lastSP
 321   }
 322   assert_different_registers(temp1, temp2, temp3, receiver_reg);
 323   assert_different_registers(temp1, temp2, temp3, member_reg);
 324 
 325   if (iid == vmIntrinsics::_invokeBasic) {
 326     // indirect through MH.form.vmentry.vmtarget
 327     jump_to_lambda_form(_masm, receiver_reg, rbx_method, temp1, for_compiler_entry);
 328 
 329   } else {
 330     // The method is a member invoker used by direct method handles.
 331     if (VerifyMethodHandles) {
 332       // make sure the trailing argument really is a MemberName (caller responsibility)
 333       verify_klass(_masm, member_reg, SystemDictionary::WK_KLASS_ENUM_NAME(java_lang_invoke_MemberName),
 334                    "MemberName required for invokeVirtual etc.");
 335     }
 336 
 337     Address member_clazz(    member_reg, NONZERO(java_lang_invoke_MemberName::clazz_offset_in_bytes()));
 338     Address member_vmindex(  member_reg, NONZERO(java_lang_invoke_MemberName::vmindex_offset_in_bytes()));
 339     Address member_vmtarget( member_reg, NONZERO(java_lang_invoke_MemberName::method_offset_in_bytes()));
 340     Address vmtarget_method( rbx_method, NONZERO(java_lang_invoke_ResolvedMethodName::vmtarget_offset_in_bytes()));
 341 
 342     Register temp1_recv_klass = temp1;
 343     if (iid != vmIntrinsics::_linkToStatic) {
 344       __ verify_oop(receiver_reg);
 345       if (iid == vmIntrinsics::_linkToSpecial) {
 346         // Don't actually load the klass; just null-check the receiver.
 347         __ null_check(receiver_reg);
 348       } else {
 349         // load receiver klass itself
 350         __ null_check(receiver_reg, oopDesc::klass_offset_in_bytes());
 351         __ load_klass(temp1_recv_klass, receiver_reg);
 352         __ verify_klass_ptr(temp1_recv_klass);
 353       }
 354       BLOCK_COMMENT("check_receiver {");
 355       // The receiver for the MemberName must be in receiver_reg.
 356       // Check the receiver against the MemberName.clazz
 357       if (VerifyMethodHandles && iid == vmIntrinsics::_linkToSpecial) {
 358         // Did not load it above...
 359         __ load_klass(temp1_recv_klass, receiver_reg);
 360         __ verify_klass_ptr(temp1_recv_klass);
 361       }
 362       if (VerifyMethodHandles && iid != vmIntrinsics::_linkToInterface) {
 363         Label L_ok;
 364         Register temp2_defc = temp2;
 365         __ load_heap_oop(temp2_defc, member_clazz, temp3);
 366         load_klass_from_Class(_masm, temp2_defc);
 367         __ verify_klass_ptr(temp2_defc);
 368         __ check_klass_subtype(temp1_recv_klass, temp2_defc, temp3, L_ok);
 369         // If we get here, the type check failed!
 370         __ STOP("receiver class disagrees with MemberName.clazz");
 371         __ bind(L_ok);
 372       }
 373       BLOCK_COMMENT("} check_receiver");
 374     }
 375     if (iid == vmIntrinsics::_linkToSpecial ||
 376         iid == vmIntrinsics::_linkToStatic) {
 377       DEBUG_ONLY(temp1_recv_klass = noreg);  // these guys didn't load the recv_klass
 378     }
 379 
 380     // Live registers at this point:
 381     //  member_reg - MemberName that was the trailing argument
 382     //  temp1_recv_klass - klass of stacked receiver, if needed
 383     //  rsi/r13 - interpreter linkage (if interpreted)
 384     //  rcx, rdx, rsi, rdi, r8 - compiler arguments (if compiled)
 385 
 386     Label L_incompatible_class_change_error;
 387     switch (iid) {
 388     case vmIntrinsics::_linkToSpecial:
 389       if (VerifyMethodHandles) {
 390         verify_ref_kind(_masm, JVM_REF_invokeSpecial, member_reg, temp3);
 391       }
 392       __ load_heap_oop(rbx_method, member_vmtarget);
 393       __ movptr(rbx_method, vmtarget_method);
 394       break;
 395 
 396     case vmIntrinsics::_linkToStatic:
 397       if (VerifyMethodHandles) {
 398         verify_ref_kind(_masm, JVM_REF_invokeStatic, member_reg, temp3);
 399       }
 400       __ load_heap_oop(rbx_method, member_vmtarget);
 401       __ movptr(rbx_method, vmtarget_method);
 402       break;
 403 
 404     case vmIntrinsics::_linkToVirtual:
 405     {
 406       // same as TemplateTable::invokevirtual,
 407       // minus the CP setup and profiling:
 408 
 409       if (VerifyMethodHandles) {
 410         verify_ref_kind(_masm, JVM_REF_invokeVirtual, member_reg, temp3);
 411       }
 412 
 413       // pick out the vtable index from the MemberName, and then we can discard it:
 414       Register temp2_index = temp2;
 415       __ movptr(temp2_index, member_vmindex);
 416 
 417       if (VerifyMethodHandles) {
 418         Label L_index_ok;
 419         __ cmpl(temp2_index, 0);
 420         __ jcc(Assembler::greaterEqual, L_index_ok);
 421         __ STOP("no virtual index");
 422         __ BIND(L_index_ok);
 423       }
 424 
 425       // Note:  The verifier invariants allow us to ignore MemberName.clazz and vmtarget
 426       // at this point.  And VerifyMethodHandles has already checked clazz, if needed.
 427 
 428       // get target Method* & entry point
 429       __ lookup_virtual_method(temp1_recv_klass, temp2_index, rbx_method);
 430       break;
 431     }
 432 
 433     case vmIntrinsics::_linkToInterface:
 434     {
 435       // same as TemplateTable::invokeinterface
 436       // (minus the CP setup and profiling, with different argument motion)
 437       if (VerifyMethodHandles) {
 438         verify_ref_kind(_masm, JVM_REF_invokeInterface, member_reg, temp3);
 439       }
 440 
 441       BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
 442 
 443       Register temp3_intf = temp3;
 444       __ load_heap_oop(temp3_intf, member_clazz);
 445       load_klass_from_Class(_masm, temp3_intf);
 446       __ verify_klass_ptr(temp3_intf);
 447 
 448       Register rbx_index = rbx_method;
 449       __ movptr(rbx_index, member_vmindex);
 450       if (VerifyMethodHandles) {
 451         Label L;
 452         __ cmpl(rbx_index, 0);
 453         __ jcc(Assembler::greaterEqual, L);
 454         __ STOP("invalid vtable index for MH.invokeInterface");
 455         __ bind(L);
 456       }
 457 
 458       // given intf, index, and recv klass, dispatch to the implementation method
 459       __ lookup_interface_method(temp1_recv_klass, temp3_intf,
 460                                  // note: next two args must be the same:
 461                                  rbx_index, rbx_method,
 462                                  temp2,
 463                                  L_incompatible_class_change_error);
 464       break;
 465     }
 466 
 467     default:
 468       fatal("unexpected intrinsic %d: %s", iid, vmIntrinsics::name_at(iid));
 469       break;
 470     }
 471 
 472     // Live at this point:
 473     //   rbx_method
 474     //   rsi/r13 (if interpreted)
 475 
 476     // After figuring out which concrete method to call, jump into it.
 477     // Note that this works in the interpreter with no data motion.
 478     // But the compiled version will require that rcx_recv be shifted out.
 479     __ verify_method_ptr(rbx_method);
 480     jump_from_method_handle(_masm, rbx_method, temp1, for_compiler_entry);
 481 
 482     if (iid == vmIntrinsics::_linkToInterface) {
 483       __ bind(L_incompatible_class_change_error);
 484       __ jump(RuntimeAddress(StubRoutines::throw_IncompatibleClassChangeError_entry()));
 485     }
 486   }
 487 }
 488 
 489 #ifndef PRODUCT
 490 void trace_method_handle_stub(const char* adaptername,
 491                               oop mh,
 492                               intptr_t* saved_regs,
 493                               intptr_t* entry_sp) {
 494   // called as a leaf from native code: do not block the JVM!
 495   bool has_mh = (strstr(adaptername, "/static") == NULL &&
 496                  strstr(adaptername, "linkTo") == NULL);    // static linkers don't have MH
 497   const char* mh_reg_name = has_mh ? "rcx_mh" : "rcx";
 498   tty->print_cr("MH %s %s=" PTR_FORMAT " sp=" PTR_FORMAT,
 499                 adaptername, mh_reg_name,
 500                 p2i(mh), p2i(entry_sp));
 501 
 502   if (Verbose) {
 503     tty->print_cr("Registers:");
 504     const int saved_regs_count = RegisterImpl::number_of_registers;
 505     for (int i = 0; i < saved_regs_count; i++) {
 506       Register r = as_Register(i);
 507       // The registers are stored in reverse order on the stack (by pusha).
 508       tty->print("%3s=" PTR_FORMAT, r->name(), saved_regs[((saved_regs_count - 1) - i)]);
 509       if ((i + 1) % 4 == 0) {
 510         tty->cr();
 511       } else {
 512         tty->print(", ");
 513       }
 514     }
 515     tty->cr();
 516 
 517     {
 518      // dumping last frame with frame::describe
 519 
 520       JavaThread* p = JavaThread::active();
 521 
 522       ResourceMark rm;
 523       PRESERVE_EXCEPTION_MARK; // may not be needed by safer and unexpensive here
 524       FrameValues values;
 525 
 526       // Note: We want to allow trace_method_handle from any call site.
 527       // While trace_method_handle creates a frame, it may be entered
 528       // without a PC on the stack top (e.g. not just after a call).
 529       // Walking that frame could lead to failures due to that invalid PC.
 530       // => carefully detect that frame when doing the stack walking
 531 
 532       // Current C frame
 533       frame cur_frame = os::current_frame();
 534 
 535       // Robust search of trace_calling_frame (independant of inlining).
 536       // Assumes saved_regs comes from a pusha in the trace_calling_frame.
 537       assert(cur_frame.sp() < saved_regs, "registers not saved on stack ?");
 538       frame trace_calling_frame = os::get_sender_for_C_frame(&cur_frame);
 539       while (trace_calling_frame.fp() < saved_regs) {
 540         trace_calling_frame = os::get_sender_for_C_frame(&trace_calling_frame);
 541       }
 542 
 543       // safely create a frame and call frame::describe
 544       intptr_t *dump_sp = trace_calling_frame.sender_sp();
 545       intptr_t *dump_fp = trace_calling_frame.link();
 546 
 547       bool walkable = has_mh; // whether the traced frame shoud be walkable
 548 
 549       if (walkable) {
 550         // The previous definition of walkable may have to be refined
 551         // if new call sites cause the next frame constructor to start
 552         // failing. Alternatively, frame constructors could be
 553         // modified to support the current or future non walkable
 554         // frames (but this is more intrusive and is not considered as
 555         // part of this RFE, which will instead use a simpler output).
 556         frame dump_frame = frame(dump_sp, dump_fp);
 557         dump_frame.describe(values, 1);
 558       } else {
 559         // Stack may not be walkable (invalid PC above FP):
 560         // Add descriptions without building a Java frame to avoid issues
 561         values.describe(-1, dump_fp, "fp for #1 <not parsed, cannot trust pc>");
 562         values.describe(-1, dump_sp, "sp for #1");
 563       }
 564       values.describe(-1, entry_sp, "raw top of stack");
 565 
 566       tty->print_cr("Stack layout:");
 567       values.print(p);
 568     }
 569     if (has_mh && oopDesc::is_oop(mh)) {
 570       mh->print();
 571       if (java_lang_invoke_MethodHandle::is_instance(mh)) {
 572         if (java_lang_invoke_MethodHandle::form_offset_in_bytes() != 0)
 573           java_lang_invoke_MethodHandle::form(mh)->print();
 574       }
 575     }
 576   }
 577 }
 578 
 579 // The stub wraps the arguments in a struct on the stack to avoid
 580 // dealing with the different calling conventions for passing 6
 581 // arguments.
 582 struct MethodHandleStubArguments {
 583   const char* adaptername;
 584   oopDesc* mh;
 585   intptr_t* saved_regs;
 586   intptr_t* entry_sp;
 587 };
 588 void trace_method_handle_stub_wrapper(MethodHandleStubArguments* args) {
 589   trace_method_handle_stub(args->adaptername,
 590                            args->mh,
 591                            args->saved_regs,
 592                            args->entry_sp);
 593 }
 594 
 595 void MethodHandles::trace_method_handle(MacroAssembler* _masm, const char* adaptername) {
 596   if (!TraceMethodHandles)  return;
 597   BLOCK_COMMENT(err_msg("trace_method_handle %s {", adaptername));
 598   __ enter();
 599   __ andptr(rsp, -16); // align stack if needed for FPU state
 600   __ pusha();
 601   __ mov(rbx, rsp); // for retreiving saved_regs
 602   // Note: saved_regs must be in the entered frame for the
 603   // robust stack walking implemented in trace_method_handle_stub.
 604 
 605   // save FP result, valid at some call sites (adapter_opt_return_float, ...)
 606   __ increment(rsp, -2 * wordSize);
 607   if  (UseSSE >= 2) {
 608     __ movdbl(Address(rsp, 0), xmm0);
 609   } else if (UseSSE == 1) {
 610     __ movflt(Address(rsp, 0), xmm0);
 611   } else {
 612     __ fst_d(Address(rsp, 0));
 613   }
 614 
 615   // Incoming state:
 616   // rcx: method handle
 617   //
 618   // To avoid calling convention issues, build a record on the stack
 619   // and pass the pointer to that instead.
 620   __ push(rbp);               // entry_sp (with extra align space)
 621   __ push(rbx);               // pusha saved_regs
 622   __ push(rcx);               // mh
 623   __ push(rcx);               // slot for adaptername
 624   __ movptr(Address(rsp, 0), (intptr_t) adaptername);
 625   __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, trace_method_handle_stub_wrapper), rsp);
 626   __ increment(rsp, sizeof(MethodHandleStubArguments));
 627 
 628   if  (UseSSE >= 2) {
 629     __ movdbl(xmm0, Address(rsp, 0));
 630   } else if (UseSSE == 1) {
 631     __ movflt(xmm0, Address(rsp, 0));
 632   } else {
 633     __ fld_d(Address(rsp, 0));
 634   }
 635   __ increment(rsp, 2 * wordSize);
 636 
 637   __ popa();
 638   __ leave();
 639   BLOCK_COMMENT("} trace_method_handle");
 640 }
 641 #endif //PRODUCT