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