1 /*
  2  * Copyright (c) 1997, 2025, 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 "asm/macroAssembler.hpp"
 26 #include "classfile/vmClasses.hpp"
 27 #include "compiler/disassembler.hpp"
 28 #include "classfile/javaClasses.inline.hpp"
 29 #include "interpreter/interpreter.hpp"
 30 #include "interpreter/interpreterRuntime.hpp"
 31 #include "jvm.h"
 32 #include "logging/log.hpp"
 33 #include "logging/logStream.hpp"
 34 #include "memory/allocation.inline.hpp"
 35 #include "memory/resourceArea.hpp"
 36 #include "prims/jvmtiExport.hpp"
 37 #include "prims/methodHandles.hpp"
 38 #include "runtime/flags/flagSetting.hpp"
 39 #include "runtime/frame.inline.hpp"
 40 #include "runtime/stubRoutines.hpp"
 41 #include "utilities/formatBuffer.hpp"
 42 #include "utilities/preserveException.hpp"
 43 
 44 #define __ Disassembler::hook<MacroAssembler>(__FILE__, __LINE__, _masm)->
 45 
 46 #ifdef PRODUCT
 47 #define BLOCK_COMMENT(str) /* nothing */
 48 #define STOP(error) stop(error)
 49 #else
 50 #define BLOCK_COMMENT(str) __ block_comment(str)
 51 #define STOP(error) block_comment(error); __ stop(error)
 52 #endif
 53 
 54 #define BIND(label) bind(label); BLOCK_COMMENT(#label ":")
 55 
 56 void MethodHandles::load_klass_from_Class(MacroAssembler* _masm, Register klass_reg) {
 57   if (VerifyMethodHandles)
 58     verify_klass(_masm, klass_reg, VM_CLASS_ID(java_lang_Class),
 59                  "MH argument is a Class");
 60   __ movptr(klass_reg, Address(klass_reg, java_lang_Class::klass_offset()));
 61 }
 62 
 63 #ifdef ASSERT
 64 static int check_nonzero(const char* xname, int x) {
 65   assert(x != 0, "%s should be nonzero", xname);
 66   return x;
 67 }
 68 #define NONZERO(x) check_nonzero(#x, x)
 69 #else //ASSERT
 70 #define NONZERO(x) (x)
 71 #endif //ASSERT
 72 
 73 #ifdef ASSERT
 74 void MethodHandles::verify_klass(MacroAssembler* _masm,
 75                                  Register obj, vmClassID klass_id,
 76                                  const char* error_message) {
 77   InstanceKlass** klass_addr = vmClasses::klass_addr_at(klass_id);
 78   Klass* klass = vmClasses::klass_at(klass_id);
 79   Register temp = rdi;
 80   Label L_ok, L_bad;
 81   BLOCK_COMMENT("verify_klass {");
 82   __ verify_oop(obj);
 83   __ testptr(obj, obj);
 84   __ jcc(Assembler::zero, L_bad);
 85 #define PUSH { __ push(temp); __ push(rscratch1);               }
 86 #define POP  {                __ pop(rscratch1);  __ pop(temp); }
 87   PUSH;
 88   __ load_klass(temp, obj, rscratch1);
 89   __ cmpptr(temp, ExternalAddress((address) klass_addr), rscratch1);
 90   __ jcc(Assembler::equal, L_ok);
 91   intptr_t super_check_offset = klass->super_check_offset();
 92   __ movptr(temp, Address(temp, super_check_offset));
 93   __ cmpptr(temp, ExternalAddress((address) klass_addr), rscratch1);
 94   __ jcc(Assembler::equal, L_ok);
 95   POP;
 96   __ bind(L_bad);
 97   __ STOP(error_message);
 98   __ BIND(L_ok);
 99   POP;
100   BLOCK_COMMENT("} verify_klass");
101 #undef POP
102 #undef PUSH
103 }
104 
105 void MethodHandles::verify_ref_kind(MacroAssembler* _masm, int ref_kind, Register member_reg, Register temp) {
106   Label L;
107   BLOCK_COMMENT("verify_ref_kind {");
108   __ movl(temp, Address(member_reg, NONZERO(java_lang_invoke_MemberName::flags_offset())));
109   __ shrl(temp, java_lang_invoke_MemberName::MN_REFERENCE_KIND_SHIFT);
110   __ andl(temp, java_lang_invoke_MemberName::MN_REFERENCE_KIND_MASK);
111   __ cmpl(temp, ref_kind);
112   __ jcc(Assembler::equal, L);
113   const char* msg = ref_kind_to_verify_msg(ref_kind);
114   if (ref_kind == JVM_REF_invokeVirtual ||
115       ref_kind == JVM_REF_invokeSpecial) {
116     // could do this for all ref_kinds, but would explode assembly code size
117     trace_method_handle(_masm, msg);
118   }
119   __ STOP(msg);
120   BLOCK_COMMENT("} verify_ref_kind");
121   __ bind(L);
122 }
123 
124 void MethodHandles::verify_method(MacroAssembler* _masm, Register method, Register temp, vmIntrinsics::ID iid) {
125   BLOCK_COMMENT("verify_method {");
126   __ verify_method_ptr(method);
127   if (VerifyMethodHandles) {
128     Label L_ok;
129     assert_different_registers(method, temp);
130 
131     const Register method_holder = temp;
132     __ load_method_holder(method_holder, method);
133     __ push_ppx(method_holder); // keep holder around for diagnostic purposes
134 
135     switch (iid) {
136       case vmIntrinsicID::_invokeBasic:
137         // Require compiled LambdaForm class to be fully initialized.
138         __ cmpb(Address(method_holder, InstanceKlass::init_state_offset()), InstanceKlass::fully_initialized);
139         __ jcc(Assembler::equal, L_ok);
140         break;
141 
142       case vmIntrinsicID::_linkToStatic:
143         __ clinit_barrier(method_holder, &L_ok);
144         break;
145 
146       case vmIntrinsicID::_linkToVirtual:
147       case vmIntrinsicID::_linkToSpecial:
148       case vmIntrinsicID::_linkToInterface:
149         // Class initialization check is too strong here. Just ensure that initialization has been initiated.
150         __ cmpb(Address(method_holder, InstanceKlass::init_state_offset()), InstanceKlass::being_initialized);
151         __ jcc(Assembler::greaterEqual, L_ok);
152 
153         // init_state check failed, but it may be an abstract interface method
154         __ load_unsigned_short(temp, Address(method, Method::access_flags_offset()));
155         __ testl(temp, JVM_ACC_ABSTRACT);
156         __ jcc(Assembler::notZero, L_ok);
157         break;
158 
159       default:
160         fatal("unexpected intrinsic %d: %s", vmIntrinsics::as_int(iid), vmIntrinsics::name_at(iid));
161     }
162 
163     // clinit check failed for a concrete method
164     __ STOP("Method holder klass is not initialized");
165 
166     __ BIND(L_ok);
167     __ pop_ppx(method_holder); // restore stack layout
168   }
169   BLOCK_COMMENT("} verify_method");
170 }
171 #endif // ASSERT
172 
173 void MethodHandles::jump_from_method_handle(MacroAssembler* _masm, Register method, Register temp,
174                                             bool for_compiler_entry, vmIntrinsics::ID iid) {
175   assert(method == rbx, "interpreter calling convention");
176 
177    Label L_no_such_method;
178    __ testptr(rbx, rbx);
179    __ jcc(Assembler::zero, L_no_such_method);
180 
181   verify_method(_masm, method, temp, iid);
182 
183   if (!for_compiler_entry && JvmtiExport::can_post_interpreter_events()) {
184     Label run_compiled_code;
185     // JVMTI events, such as single-stepping, are implemented partly by avoiding running
186     // compiled code in threads for which the event is enabled.  Check here for
187     // interp_only_mode if these events CAN be enabled.
188     // interp_only is an int, on little endian it is sufficient to test the byte only
189     // Is a cmpl faster?
190     __ cmpb(Address(r15_thread, JavaThread::interp_only_mode_offset()), 0);
191     __ jccb(Assembler::zero, run_compiled_code);
192     __ jmp(Address(method, Method::interpreter_entry_offset()));
193     __ BIND(run_compiled_code);
194   }
195 
196   const ByteSize entry_offset = for_compiler_entry ? Method::from_compiled_offset() :
197                                                      Method::from_interpreted_offset();
198   __ jmp(Address(method, entry_offset));
199 
200   __ bind(L_no_such_method);
201   __ jump(RuntimeAddress(SharedRuntime::throw_AbstractMethodError_entry()));
202 }
203 
204 void MethodHandles::jump_to_lambda_form(MacroAssembler* _masm,
205                                         Register recv, Register method_temp,
206                                         Register temp2,
207                                         bool for_compiler_entry) {
208   BLOCK_COMMENT("jump_to_lambda_form {");
209   // This is the initial entry point of a lazy method handle.
210   // After type checking, it picks up the invoker from the LambdaForm.
211   assert_different_registers(recv, method_temp, temp2);
212   assert(recv != noreg, "required register");
213   assert(method_temp == rbx, "required register for loading method");
214 
215   // Load the invoker, as MH -> MH.form -> LF.vmentry
216   __ verify_oop(recv);
217   __ load_heap_oop(method_temp, Address(recv, NONZERO(java_lang_invoke_MethodHandle::form_offset())), temp2);
218   __ verify_oop(method_temp);
219   __ load_heap_oop(method_temp, Address(method_temp, NONZERO(java_lang_invoke_LambdaForm::vmentry_offset())), temp2);
220   __ verify_oop(method_temp);
221   __ load_heap_oop(method_temp, Address(method_temp, NONZERO(java_lang_invoke_MemberName::method_offset())), temp2);
222   __ verify_oop(method_temp);
223   __ access_load_at(T_ADDRESS, IN_HEAP, method_temp,
224                     Address(method_temp, NONZERO(java_lang_invoke_ResolvedMethodName::vmtarget_offset())),
225                     noreg);
226 
227   if (VerifyMethodHandles && !for_compiler_entry) {
228     // make sure recv is already on stack
229     __ movptr(temp2, Address(method_temp, Method::const_offset()));
230     __ load_sized_value(temp2,
231                         Address(temp2, ConstMethod::size_of_parameters_offset()),
232                         sizeof(u2), /*is_signed*/ false);
233     // assert(sizeof(u2) == sizeof(Method::_size_of_parameters), "");
234     Label L;
235     __ cmpoop(recv, __ argument_address(temp2, -1));
236     __ jcc(Assembler::equal, L);
237     __ movptr(rax, __ argument_address(temp2, -1));
238     __ STOP("receiver not on stack");
239     __ BIND(L);
240   }
241 
242   jump_from_method_handle(_masm, method_temp, temp2, for_compiler_entry, vmIntrinsics::_invokeBasic);
243   BLOCK_COMMENT("} jump_to_lambda_form");
244 }
245 
246 void MethodHandles::jump_to_native_invoker(MacroAssembler* _masm, Register nep_reg, Register temp_target) {
247   BLOCK_COMMENT("jump_to_native_invoker {");
248   assert_different_registers(nep_reg, temp_target);
249   assert(nep_reg != noreg, "required register");
250 
251   // Load the invoker, as NEP -> .invoker
252   __ verify_oop(nep_reg);
253   __ access_load_at(T_ADDRESS, IN_HEAP, temp_target,
254                     Address(nep_reg, NONZERO(jdk_internal_foreign_abi_NativeEntryPoint::downcall_stub_address_offset_in_bytes())),
255                     noreg);
256 
257   __ jmp(temp_target);
258   BLOCK_COMMENT("} jump_to_native_invoker");
259 }
260 
261 
262 // Code generation
263 address MethodHandles::generate_method_handle_interpreter_entry(MacroAssembler* _masm,
264                                                                 vmIntrinsics::ID iid) {
265   const bool not_for_compiler_entry = false;  // this is the interpreter entry
266   assert(is_signature_polymorphic(iid), "expected invoke iid");
267   if (iid == vmIntrinsics::_invokeGeneric ||
268       iid == vmIntrinsics::_compiledLambdaForm) {
269     // Perhaps surprisingly, the symbolic references visible to Java are not directly used.
270     // They are linked to Java-generated adapters via MethodHandleNatives.linkMethod.
271     // They all allow an appendix argument.
272     __ hlt();           // empty stubs make SG sick
273     return nullptr;
274   }
275 
276   // No need in interpreter entry for linkToNative for now.
277   // Interpreter calls compiled entry through i2c.
278   if (iid == vmIntrinsics::_linkToNative) {
279     __ hlt();
280     return nullptr;
281   }
282 
283   // rsi/r13: sender SP (must preserve; see prepare_to_jump_from_interpreted)
284   // rbx: Method*
285   // rdx: argument locator (parameter slot count, added to rsp)
286   // rcx: used as temp to hold mh or receiver
287   // rax, rdi: garbage temps, blown away
288   Register rdx_argp   = rdx;   // argument list ptr, live on error paths
289   Register rax_temp   = rax;
290   Register rcx_mh     = rcx;   // MH receiver; dies quickly and is recycled
291   Register rbx_method = rbx;   // eventual target of this invocation
292 
293   // here's where control starts out:
294   __ align(CodeEntryAlignment);
295   address entry_point = __ pc();
296 
297   if (VerifyMethodHandles) {
298     assert(Method::intrinsic_id_size_in_bytes() == 2, "assuming Method::_intrinsic_id is u2");
299 
300     Label L;
301     BLOCK_COMMENT("verify_intrinsic_id {");
302     __ cmpw(Address(rbx_method, Method::intrinsic_id_offset()), (int) iid);
303     __ jcc(Assembler::equal, L);
304     if (iid == vmIntrinsics::_linkToVirtual ||
305         iid == vmIntrinsics::_linkToSpecial) {
306       // could do this for all kinds, but would explode assembly code size
307       trace_method_handle(_masm, "bad Method*::intrinsic_id");
308     }
309     __ STOP("bad Method*::intrinsic_id");
310     __ bind(L);
311     BLOCK_COMMENT("} verify_intrinsic_id");
312   }
313 
314   // First task:  Find out how big the argument list is.
315   Address rdx_first_arg_addr;
316   int ref_kind = signature_polymorphic_intrinsic_ref_kind(iid);
317   assert(ref_kind != 0 || iid == vmIntrinsics::_invokeBasic, "must be _invokeBasic or a linkTo intrinsic");
318   if (ref_kind == 0 || MethodHandles::ref_kind_has_receiver(ref_kind)) {
319     __ movptr(rdx_argp, Address(rbx_method, Method::const_offset()));
320     __ load_sized_value(rdx_argp,
321                         Address(rdx_argp, ConstMethod::size_of_parameters_offset()),
322                         sizeof(u2), /*is_signed*/ false);
323     // assert(sizeof(u2) == sizeof(Method::_size_of_parameters), "");
324     rdx_first_arg_addr = __ argument_address(rdx_argp, -1);
325   } else {
326     DEBUG_ONLY(rdx_argp = noreg);
327   }
328 
329   if (!is_signature_polymorphic_static(iid)) {
330     __ movptr(rcx_mh, rdx_first_arg_addr);
331     DEBUG_ONLY(rdx_argp = noreg);
332   }
333 
334   // rdx_first_arg_addr is live!
335 
336   trace_method_handle_interpreter_entry(_masm, iid);
337 
338   if (iid == vmIntrinsics::_invokeBasic) {
339     generate_method_handle_dispatch(_masm, iid, rcx_mh, noreg, not_for_compiler_entry);
340 
341   } else {
342     // Adjust argument list by popping the trailing MemberName argument.
343     Register rcx_recv = noreg;
344     if (MethodHandles::ref_kind_has_receiver(ref_kind)) {
345       // Load the receiver (not the MH; the actual MemberName's receiver) up from the interpreter stack.
346       __ movptr(rcx_recv = rcx, rdx_first_arg_addr);
347     }
348     DEBUG_ONLY(rdx_argp = noreg);
349     Register rbx_member = rbx_method;  // MemberName ptr; incoming method ptr is dead now
350     __ pop(rax_temp);           // return address
351     __ pop(rbx_member);         // extract last argument
352     __ push(rax_temp);          // re-push return address
353     generate_method_handle_dispatch(_masm, iid, rcx_recv, rbx_member, not_for_compiler_entry);
354   }
355 
356   return entry_point;
357 }
358 
359 void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
360                                                     vmIntrinsics::ID iid,
361                                                     Register receiver_reg,
362                                                     Register member_reg,
363                                                     bool for_compiler_entry) {
364   assert(is_signature_polymorphic(iid), "expected invoke iid");
365   Register rbx_method = rbx;   // eventual target of this invocation
366   // temps used in this code are not used in *either* compiled or interpreted calling sequences
367   Register temp1 = rscratch1;
368   Register temp2 = rscratch2;
369   Register temp3 = rax;
370   if (for_compiler_entry) {
371     assert(receiver_reg == (iid == vmIntrinsics::_linkToStatic || iid == vmIntrinsics::_linkToNative ? noreg : j_rarg0), "only valid assignment");
372     assert_different_registers(temp1,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5);
373     assert_different_registers(temp2,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5);
374     assert_different_registers(temp3,        j_rarg0, j_rarg1, j_rarg2, j_rarg3, j_rarg4, j_rarg5);
375   } else {
376     assert_different_registers(temp1, temp2, temp3, saved_last_sp_register());  // don't trash lastSP
377   }
378   assert_different_registers(temp1, temp2, temp3, receiver_reg);
379   assert_different_registers(temp1, temp2, temp3, member_reg);
380 
381   if (iid == vmIntrinsics::_invokeBasic) {
382     // indirect through MH.form.vmentry.vmtarget
383     jump_to_lambda_form(_masm, receiver_reg, rbx_method, temp1, for_compiler_entry);
384   } else if (iid == vmIntrinsics::_linkToNative) {
385     assert(for_compiler_entry, "only compiler entry is supported");
386     jump_to_native_invoker(_masm, member_reg, temp1);
387   } else {
388     // The method is a member invoker used by direct method handles.
389     if (VerifyMethodHandles) {
390       // make sure the trailing argument really is a MemberName (caller responsibility)
391       verify_klass(_masm, member_reg, VM_CLASS_ID(java_lang_invoke_MemberName),
392                    "MemberName required for invokeVirtual etc.");
393     }
394 
395     Address member_clazz(    member_reg, NONZERO(java_lang_invoke_MemberName::clazz_offset()));
396     Address member_vmindex(  member_reg, NONZERO(java_lang_invoke_MemberName::vmindex_offset()));
397     Address member_vmtarget( member_reg, NONZERO(java_lang_invoke_MemberName::method_offset()));
398     Address vmtarget_method( rbx_method, NONZERO(java_lang_invoke_ResolvedMethodName::vmtarget_offset()));
399 
400     Register temp1_recv_klass = temp1;
401     if (iid != vmIntrinsics::_linkToStatic) {
402       __ verify_oop(receiver_reg);
403       if (iid == vmIntrinsics::_linkToSpecial) {
404         // Don't actually load the klass; just null-check the receiver.
405         __ null_check(receiver_reg);
406       } else {
407         // load receiver klass itself
408         __ load_klass(temp1_recv_klass, receiver_reg, temp2);
409         __ verify_klass_ptr(temp1_recv_klass);
410       }
411       BLOCK_COMMENT("check_receiver {");
412       // The receiver for the MemberName must be in receiver_reg.
413       // Check the receiver against the MemberName.clazz
414       if (VerifyMethodHandles && iid == vmIntrinsics::_linkToSpecial) {
415         // Did not load it above...
416         __ load_klass(temp1_recv_klass, receiver_reg, temp2);
417         __ verify_klass_ptr(temp1_recv_klass);
418       }
419       if (VerifyMethodHandles && iid != vmIntrinsics::_linkToInterface) {
420         Label L_ok;
421         Register temp2_defc = temp2;
422         __ load_heap_oop(temp2_defc, member_clazz, temp3);
423         load_klass_from_Class(_masm, temp2_defc);
424         __ verify_klass_ptr(temp2_defc);
425         __ check_klass_subtype(temp1_recv_klass, temp2_defc, temp3, L_ok);
426         // If we get here, the type check failed!
427         __ STOP("receiver class disagrees with MemberName.clazz");
428         __ bind(L_ok);
429       }
430       BLOCK_COMMENT("} check_receiver");
431     }
432     if (iid == vmIntrinsics::_linkToSpecial ||
433         iid == vmIntrinsics::_linkToStatic) {
434       DEBUG_ONLY(temp1_recv_klass = noreg);  // these guys didn't load the recv_klass
435     }
436 
437     // Live registers at this point:
438     //  member_reg - MemberName that was the trailing argument
439     //  temp1_recv_klass - klass of stacked receiver, if needed
440     //  rsi/r13 - interpreter linkage (if interpreted)
441     //  rcx, rdx, rsi, rdi, r8 - compiler arguments (if compiled)
442 
443     Label L_incompatible_class_change_error;
444     switch (iid) {
445     case vmIntrinsics::_linkToSpecial:
446       if (VerifyMethodHandles) {
447         verify_ref_kind(_masm, JVM_REF_invokeSpecial, member_reg, temp3);
448       }
449       __ load_heap_oop(rbx_method, member_vmtarget);
450       __ access_load_at(T_ADDRESS, IN_HEAP, rbx_method, vmtarget_method, noreg);
451       break;
452 
453     case vmIntrinsics::_linkToStatic:
454       if (VerifyMethodHandles) {
455         verify_ref_kind(_masm, JVM_REF_invokeStatic, member_reg, temp3);
456       }
457       __ load_heap_oop(rbx_method, member_vmtarget);
458       __ access_load_at(T_ADDRESS, IN_HEAP, rbx_method, vmtarget_method, noreg);
459       break;
460 
461     case vmIntrinsics::_linkToVirtual:
462     {
463       // same as TemplateTable::invokevirtual,
464       // minus the CP setup and profiling:
465 
466       if (VerifyMethodHandles) {
467         verify_ref_kind(_masm, JVM_REF_invokeVirtual, member_reg, temp3);
468       }
469 
470       // pick out the vtable index from the MemberName, and then we can discard it:
471       Register temp2_index = temp2;
472       __ access_load_at(T_ADDRESS, IN_HEAP, temp2_index, member_vmindex, noreg);
473 
474       if (VerifyMethodHandles) {
475         Label L_index_ok;
476         __ cmpl(temp2_index, 0);
477         __ jcc(Assembler::greaterEqual, L_index_ok);
478         __ STOP("no virtual index");
479         __ BIND(L_index_ok);
480       }
481 
482       // Note:  The verifier invariants allow us to ignore MemberName.clazz and vmtarget
483       // at this point.  And VerifyMethodHandles has already checked clazz, if needed.
484 
485       // get target Method* & entry point
486       __ lookup_virtual_method(temp1_recv_klass, temp2_index, rbx_method);
487       break;
488     }
489 
490     case vmIntrinsics::_linkToInterface:
491     {
492       // same as TemplateTable::invokeinterface
493       // (minus the CP setup and profiling, with different argument motion)
494       if (VerifyMethodHandles) {
495         verify_ref_kind(_masm, JVM_REF_invokeInterface, member_reg, temp3);
496       }
497 
498       Register temp3_intf = temp3;
499       __ load_heap_oop(temp3_intf, member_clazz);
500       load_klass_from_Class(_masm, temp3_intf);
501       __ verify_klass_ptr(temp3_intf);
502 
503       Register rbx_index = rbx_method;
504       __ access_load_at(T_ADDRESS, IN_HEAP, rbx_index, member_vmindex, noreg);
505       if (VerifyMethodHandles) {
506         Label L;
507         __ cmpl(rbx_index, 0);
508         __ jcc(Assembler::greaterEqual, L);
509         __ STOP("invalid vtable index for MH.invokeInterface");
510         __ bind(L);
511       }
512 
513       // given intf, index, and recv klass, dispatch to the implementation method
514       __ lookup_interface_method(temp1_recv_klass, temp3_intf,
515                                  // note: next two args must be the same:
516                                  rbx_index, rbx_method,
517                                  temp2,
518                                  L_incompatible_class_change_error);
519       break;
520     }
521 
522     default:
523       fatal("unexpected intrinsic %d: %s", vmIntrinsics::as_int(iid), vmIntrinsics::name_at(iid));
524       break;
525     }
526 
527     // Live at this point:
528     //   rbx_method
529     //   rsi/r13 (if interpreted)
530 
531     // After figuring out which concrete method to call, jump into it.
532     // Note that this works in the interpreter with no data motion.
533     // But the compiled version will require that rcx_recv be shifted out.
534     jump_from_method_handle(_masm, rbx_method, temp1, for_compiler_entry, iid);
535 
536     if (iid == vmIntrinsics::_linkToInterface) {
537       __ bind(L_incompatible_class_change_error);
538       __ jump(RuntimeAddress(SharedRuntime::throw_IncompatibleClassChangeError_entry()));
539     }
540   }
541 }
542 
543 #ifndef PRODUCT
544 void trace_method_handle_stub(const char* adaptername,
545                               oopDesc* mh,
546                               intptr_t* saved_regs,
547                               intptr_t* entry_sp) {
548   // called as a leaf from native code: do not block the JVM!
549   bool has_mh = (strstr(adaptername, "/static") == nullptr &&
550                  strstr(adaptername, "linkTo") == nullptr);    // static linkers don't have MH
551   const char* mh_reg_name = has_mh ? "rcx_mh" : "rcx";
552   log_info(methodhandles)("MH %s %s=" PTR_FORMAT " sp=" PTR_FORMAT, adaptername, mh_reg_name, p2i(mh), p2i(entry_sp));
553 
554   LogTarget(Trace, methodhandles) lt;
555   if (lt.is_enabled()) {
556     ResourceMark rm;
557     LogStream ls(lt);
558     ls.print_cr("Registers:");
559     const int saved_regs_count = Register::number_of_registers;
560     for (int i = 0; i < saved_regs_count; i++) {
561       Register r = as_Register(i);
562       // The registers are stored in reverse order on the stack (by pusha).
563       int num_regs = UseAPX ? 32 : 16;
564       assert(Register::available_gp_registers() == num_regs, "sanity");
565       if (r == rsp) {
566         // rsp is actually not stored by pusha(), compute the old rsp from saved_regs (rsp after pusha): saved_regs + 16 = old rsp
567         ls.print("%3s=" PTR_FORMAT, r->name(), (intptr_t)(&saved_regs[num_regs]));
568       } else {
569         ls.print("%3s=" PTR_FORMAT, r->name(), saved_regs[((saved_regs_count - 1) - i)]);
570       }
571       if ((i + 1) % 4 == 0) {
572         ls.cr();
573       } else {
574         ls.print(", ");
575       }
576     }
577     ls.cr();
578 
579     // Note: We want to allow trace_method_handle from any call site.
580     // While trace_method_handle creates a frame, it may be entered
581     // without a PC on the stack top (e.g. not just after a call).
582     // Walking that frame could lead to failures due to that invalid PC.
583     // => carefully detect that frame when doing the stack walking
584 
585     {
586       // dumping last frame with frame::describe
587 
588       JavaThread* p = JavaThread::active();
589 
590       // may not be needed by safer and unexpensive here
591       PreserveExceptionMark pem(Thread::current());
592       FrameValues values;
593 
594       frame cur_frame = os::current_frame();
595 
596       if (cur_frame.fp() != nullptr) { // not walkable
597 
598         // Robust search of trace_calling_frame (independent of inlining).
599         // Assumes saved_regs comes from a pusha in the trace_calling_frame.
600         //
601         // We have to start the search from cur_frame, because trace_calling_frame may be it.
602         // It is guaranteed that trace_calling_frame is different from the top frame.
603         // But os::current_frame() does NOT return the top frame: it returns the next frame under it (caller's frame).
604         // (Due to inlining and tail call optimizations, caller's frame doesn't necessarily correspond to the immediate
605         // caller in the source code.)
606         assert(cur_frame.sp() < saved_regs, "registers not saved on stack ?");
607         frame trace_calling_frame = cur_frame;
608         while (trace_calling_frame.fp() < saved_regs) {
609           assert(trace_calling_frame.cb() == nullptr, "not a C frame");
610           trace_calling_frame = os::get_sender_for_C_frame(&trace_calling_frame);
611         }
612         assert(trace_calling_frame.sp() < saved_regs, "wrong frame");
613 
614         // safely create a frame and call frame::describe
615         intptr_t *dump_sp = trace_calling_frame.sender_sp();
616         intptr_t *dump_fp = trace_calling_frame.link();
617 
618         if (has_mh) {
619           // The previous definition of walkable may have to be refined
620           // if new call sites cause the next frame constructor to start
621           // failing. Alternatively, frame constructors could be
622           // modified to support the current or future non walkable
623           // frames (but this is more intrusive and is not considered as
624           // part of this RFE, which will instead use a simpler output).
625           frame dump_frame = frame(dump_sp, dump_fp);
626           dump_frame.describe(values, 1);
627         } else {
628           // Stack may not be walkable (invalid PC above FP):
629           // Add descriptions without building a Java frame to avoid issues
630           values.describe(-1, dump_fp, "fp for #1 <not parsed, cannot trust pc>");
631           values.describe(-1, dump_sp, "sp for #1");
632         }
633       }
634       values.describe(-1, entry_sp, "raw top of stack");
635 
636       ls.print_cr("Stack layout:");
637       values.print_on(p, &ls);
638     }
639     if (has_mh && oopDesc::is_oop(mh)) {
640       mh->print_on(&ls);
641       if (java_lang_invoke_MethodHandle::is_instance(mh)) {
642         java_lang_invoke_MethodHandle::form(mh)->print_on(&ls);
643       }
644     }
645   }
646 }
647 
648 // The stub wraps the arguments in a struct on the stack to avoid
649 // dealing with the different calling conventions for passing 6
650 // arguments.
651 struct MethodHandleStubArguments {
652   const char* adaptername;
653   oopDesc* mh;
654   intptr_t* saved_regs;
655   intptr_t* entry_sp;
656 };
657 void trace_method_handle_stub_wrapper(MethodHandleStubArguments* args) {
658   trace_method_handle_stub(args->adaptername,
659                            args->mh,
660                            args->saved_regs,
661                            args->entry_sp);
662 }
663 
664 void MethodHandles::trace_method_handle(MacroAssembler* _masm, const char* adaptername) {
665   if (!log_is_enabled(Info, methodhandles))  return;
666   BLOCK_COMMENT(err_msg("trace_method_handle %s {", adaptername));
667   __ enter();
668   __ andptr(rsp, -16); // align stack if needed for FPU state
669   __ pusha();
670   __ mov(rbx, rsp); // for retrieving saved_regs
671   // Note: saved_regs must be in the entered frame for the
672   // robust stack walking implemented in trace_method_handle_stub.
673 
674   // save FP result, valid at some call sites (adapter_opt_return_float, ...)
675   __ decrement(rsp, 2 * wordSize);
676   __ movdbl(Address(rsp, 0), xmm0);
677 
678   // Incoming state:
679   // rcx: method handle
680   //
681   // To avoid calling convention issues, build a record on the stack
682   // and pass the pointer to that instead.
683   __ push(rbp);               // entry_sp (with extra align space)
684   __ push(rbx);               // pusha saved_regs
685   __ push(rcx);               // mh
686   __ push(rcx);               // slot for adaptername
687   __ movptr(Address(rsp, 0), (intptr_t) adaptername, rscratch1);
688   __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, trace_method_handle_stub_wrapper), rsp);
689   __ increment(rsp, sizeof(MethodHandleStubArguments));
690 
691   __ movdbl(xmm0, Address(rsp, 0));
692   __ increment(rsp, 2 * wordSize);
693 
694   __ popa();
695   __ leave();
696   BLOCK_COMMENT("} trace_method_handle");
697 }
698 #endif //PRODUCT