linkResolver.cpp

/*
 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "cds/archiveUtils.hpp"
#include "classfile/classLoader.hpp"
#include "classfile/defaultMethods.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmClasses.hpp"
#include "classfile/vmSymbols.hpp"
#include "compiler/compilationPolicy.hpp"
#include "compiler/compileBroker.hpp"
#include "gc/shared/collectedHeap.inline.hpp"
#include "interpreter/bootstrapInfo.hpp"
#include "interpreter/bytecode.hpp"
#include "interpreter/interpreterRuntime.hpp"
#include "interpreter/linkResolver.hpp"
#include "jvm.h"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/resourceArea.hpp"
#include "oops/constantPool.inline.hpp"
#include "oops/cpCache.inline.hpp"
#include "oops/instanceKlass.inline.hpp"
#include "oops/klass.inline.hpp"
#include "oops/method.inline.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.hpp"
#include "oops/oop.inline.hpp"
#include "oops/resolvedIndyEntry.hpp"
#include "oops/symbolHandle.hpp"
#include "prims/jvmtiExport.hpp"
#include "prims/methodHandles.hpp"
#include "runtime/fieldDescriptor.inline.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/javaThread.inline.hpp"
#include "runtime/perfData.hpp"
#include "runtime/reflection.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/signature.hpp"
#include "runtime/vmThread.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_JFR
#include "jfr/jfr.hpp"
#endif

//------------------------------------------------------------------------------------------------------------------------
// Implementation of CallInfo


void CallInfo::set_static(Klass* resolved_klass, const methodHandle& resolved_method, TRAPS) {
  int vtable_index = Method::nonvirtual_vtable_index;
  set_common(resolved_klass, resolved_method, resolved_method, CallInfo::direct_call, vtable_index, CHECK);
}


void CallInfo::set_interface(Klass* resolved_klass,
                             const methodHandle& resolved_method,
                             const methodHandle& selected_method,
                             int itable_index, TRAPS) {
  // This is only called for interface methods. If the resolved_method
  // comes from java/lang/Object, it can be the subject of a virtual call, so
  // we should pick the vtable index from the resolved method.
  // In that case, the caller must call set_virtual instead of set_interface.
  assert(resolved_method->method_holder()->is_interface(), "");
  assert(itable_index == resolved_method->itable_index(), "");
  set_common(resolved_klass, resolved_method, selected_method, CallInfo::itable_call, itable_index, CHECK);
}

void CallInfo::set_virtual(Klass* resolved_klass,
                           const methodHandle& resolved_method,
                           const methodHandle& selected_method,
                           int vtable_index, TRAPS) {
  assert(vtable_index >= 0 || vtable_index == Method::nonvirtual_vtable_index, "valid index");
  assert(vtable_index < 0 || !resolved_method->has_vtable_index() || vtable_index == resolved_method->vtable_index(), "");
  CallKind kind = (vtable_index >= 0 && !resolved_method->can_be_statically_bound() ? CallInfo::vtable_call : CallInfo::direct_call);
  set_common(resolved_klass, resolved_method, selected_method, kind, vtable_index, CHECK);
  assert(!resolved_method->is_compiled_lambda_form(), "these must be handled via an invokehandle call");
}

void CallInfo::set_handle(Klass* resolved_klass,
                          const methodHandle& resolved_method,
                          Handle resolved_appendix, TRAPS) {
  guarantee(resolved_method.not_null(), "resolved method is null");
  assert(resolved_method->intrinsic_id() == vmIntrinsics::_invokeBasic ||
         resolved_method->is_compiled_lambda_form(),
         "linkMethod must return one of these");
  int vtable_index = Method::nonvirtual_vtable_index;
  assert(!resolved_method->has_vtable_index(), "");
  set_common(resolved_klass, resolved_method, resolved_method, CallInfo::direct_call, vtable_index, CHECK);
  _resolved_appendix = resolved_appendix;
}

// Redefinition safepoint may have updated the method. Make sure the new version of the method is returned.
// Callers are responsible for not safepointing and storing this method somewhere safe where redefinition
// can replace it if runs again.  Safe places are constant pool cache and code cache metadata.
// The old method is safe in CallInfo since its a methodHandle (it won't get deleted), and accessed with these
// accessors.
Method* CallInfo::resolved_method() const {
  if (JvmtiExport::can_hotswap_or_post_breakpoint() && _resolved_method->is_old()) {
    return _resolved_method->get_new_method();
  } else {
    return _resolved_method();
  }
}

Method* CallInfo::selected_method() const {
  if (JvmtiExport::can_hotswap_or_post_breakpoint() && _selected_method->is_old()) {
    return _selected_method->get_new_method();
  } else {
    return _selected_method();
  }
}

void CallInfo::set_common(Klass* resolved_klass,
                          const methodHandle& resolved_method,
                          const methodHandle& selected_method,
                          CallKind kind,
                          int index,
                          TRAPS) {
  if (selected_method.not_null()) {
    assert(resolved_method->signature() == selected_method->signature(), "signatures must correspond");
  }
  _resolved_klass  = resolved_klass;
  _resolved_method = resolved_method;
  _selected_method = selected_method;
  _call_kind       = kind;
  _call_index      = index;
  _resolved_appendix = Handle();
  DEBUG_ONLY(verify());  // verify before making side effects

  if (selected_method.not_null()) {
    CompilationPolicy::compile_if_required(selected_method, THREAD);
  }
}

// utility query for unreflecting a method
CallInfo::CallInfo(Method* resolved_method, Klass* resolved_klass, TRAPS) {
  Klass* resolved_method_holder = resolved_method->method_holder();
  if (resolved_klass == nullptr) { // 2nd argument defaults to holder of 1st
    resolved_klass = resolved_method_holder;
  }
  _resolved_klass  = resolved_klass;
  _resolved_method = methodHandle(THREAD, resolved_method);
  _selected_method = methodHandle(THREAD, resolved_method);
  // classify:
  CallKind kind = CallInfo::unknown_kind;
  int index = resolved_method->vtable_index();
  if (resolved_method->can_be_statically_bound()) {
    kind = CallInfo::direct_call;
  } else if (!resolved_method_holder->is_interface()) {
    // Could be an Object method inherited into an interface, but still a vtable call.
    kind = CallInfo::vtable_call;
  } else if (!resolved_klass->is_interface()) {
    // A default or miranda method.  Compute the vtable index.
    index = LinkResolver::vtable_index_of_interface_method(resolved_klass, _resolved_method);
    assert(index >= 0 , "we should have valid vtable index at this point");

    kind = CallInfo::vtable_call;
  } else if (resolved_method->has_vtable_index()) {
    // Can occur if an interface redeclares a method of Object.

#ifdef ASSERT
    // Ensure that this is really the case.
    Klass* object_klass = vmClasses::Object_klass();
    Method * object_resolved_method = object_klass->vtable().method_at(index);
    assert(object_resolved_method->name() == resolved_method->name(),
      "Object and interface method names should match at vtable index %d, %s != %s",
      index, object_resolved_method->name()->as_C_string(), resolved_method->name()->as_C_string());
    assert(object_resolved_method->signature() == resolved_method->signature(),
      "Object and interface method signatures should match at vtable index %d, %s != %s",
      index, object_resolved_method->signature()->as_C_string(), resolved_method->signature()->as_C_string());
#endif // ASSERT

    kind = CallInfo::vtable_call;
  } else {
    // A regular interface call.
    kind = CallInfo::itable_call;
    index = resolved_method->itable_index();
  }
  assert(index == Method::nonvirtual_vtable_index || index >= 0, "bad index %d", index);
  _call_kind  = kind;
  _call_index = index;
  _resolved_appendix = Handle();
  // Find or create a ResolvedMethod instance for this Method*
  set_resolved_method_name(CHECK);

  DEBUG_ONLY(verify());
}

void CallInfo::set_resolved_method_name(TRAPS) {
  assert(_resolved_method() != nullptr, "Should already have a Method*");
  oop rmethod_name = java_lang_invoke_ResolvedMethodName::find_resolved_method(_resolved_method, CHECK);
  _resolved_method_name = Handle(THREAD, rmethod_name);
}

#ifdef ASSERT
void CallInfo::verify() {
  switch (call_kind()) {  // the meaning and allowed value of index depends on kind
  case CallInfo::direct_call:
    if (_call_index == Method::nonvirtual_vtable_index)  break;
    // else fall through to check vtable index:
  case CallInfo::vtable_call:
    assert(resolved_klass()->verify_vtable_index(_call_index), "");
    break;
  case CallInfo::itable_call:
    assert(resolved_method()->method_holder()->verify_itable_index(_call_index), "");
    break;
  case CallInfo::unknown_kind:
    assert(call_kind() != CallInfo::unknown_kind, "CallInfo must be set");
    break;
  default:
    fatal("Unexpected call kind %d", call_kind());
  }
}
#endif // ASSERT

#ifndef PRODUCT
void CallInfo::print() {
  ResourceMark rm;
  const char* kindstr;
  switch (_call_kind) {
  case direct_call: kindstr = "direct";  break;
  case vtable_call: kindstr = "vtable";  break;
  case itable_call: kindstr = "itable";  break;
  default         : kindstr = "unknown"; break;
  }
  tty->print_cr("Call %s@%d %s", kindstr, _call_index,
                _resolved_method.is_null() ? "(none)" : _resolved_method->name_and_sig_as_C_string());
}
#endif

//------------------------------------------------------------------------------------------------------------------------
// Implementation of LinkInfo

LinkInfo::LinkInfo(const constantPoolHandle& pool, int index, const methodHandle& current_method, Bytecodes::Code code, TRAPS) {
   // resolve klass
  _resolved_klass = pool->klass_ref_at(index, code, CHECK);

  // Get name, signature, and static klass
  _name          = pool->name_ref_at(index, code);
  _signature     = pool->signature_ref_at(index, code);
  _tag           = pool->tag_ref_at(index, code);
  _current_klass = pool->pool_holder();
  _current_method = current_method;

  // Coming from the constant pool always checks access
  _check_access  = true;
  _check_loader_constraints = true;
}

LinkInfo::LinkInfo(const constantPoolHandle& pool, int index, Bytecodes::Code code, TRAPS) {
   // resolve klass
  _resolved_klass = pool->klass_ref_at(index, code, CHECK);

  // Get name, signature, and static klass
  _name          = pool->name_ref_at(index, code);
  _signature     = pool->signature_ref_at(index, code);
  _tag           = pool->tag_ref_at(index, code);
  _current_klass = pool->pool_holder();
  _current_method = methodHandle();

  // Coming from the constant pool always checks access
  _check_access  = true;
  _check_loader_constraints = true;
}

#ifndef PRODUCT
void LinkInfo::print() {
  ResourceMark rm;
  tty->print_cr("Link resolved_klass=%s name=%s signature=%s current_klass=%s check_access=%s check_loader_constraints=%s",
                _resolved_klass->name()->as_C_string(),
                _name->as_C_string(),
                _signature->as_C_string(),
                _current_klass == nullptr ? "(none)" : _current_klass->name()->as_C_string(),
                _check_access ? "true" : "false",
                _check_loader_constraints ? "true" : "false");

}
#endif // PRODUCT
//------------------------------------------------------------------------------------------------------------------------
// Klass resolution

void LinkResolver::check_klass_accessibility(Klass* ref_klass, Klass* sel_klass, TRAPS) {
  Klass* base_klass = sel_klass;
  if (sel_klass->is_objArray_klass()) {
    base_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
  }
  // The element type could be a typeArray - we only need the access
  // check if it is a reference to another class.
  if (!base_klass->is_instance_klass()) {
    return;  // no relevant check to do
  }

  Reflection::VerifyClassAccessResults vca_result =
    Reflection::verify_class_access(ref_klass, InstanceKlass::cast(base_klass), true);
  if (vca_result != Reflection::ACCESS_OK) {
    ResourceMark rm(THREAD);
    char* msg = Reflection::verify_class_access_msg(ref_klass,
                                                    InstanceKlass::cast(base_klass),
                                                    vca_result);

    // Names are all known to be < 64k so we know this formatted message is not excessively large.

    bool same_module = (base_klass->module() == ref_klass->module());
    if (msg == nullptr) {
      Exceptions::fthrow(
        THREAD_AND_LOCATION,
        vmSymbols::java_lang_IllegalAccessError(),
        "failed to access class %s from class %s (%s%s%s)",
        base_klass->external_name(),
        ref_klass->external_name(),
        (same_module) ? base_klass->joint_in_module_of_loader(ref_klass) : base_klass->class_in_module_of_loader(),
        (same_module) ? "" : "; ",
        (same_module) ? "" : ref_klass->class_in_module_of_loader());
    } else {
      // Use module specific message returned by verify_class_access_msg().
      Exceptions::fthrow(
        THREAD_AND_LOCATION,
        vmSymbols::java_lang_IllegalAccessError(),
        "%s", msg);
    }
  }
}

//------------------------------------------------------------------------------------------------------------------------
// Method resolution
//
// According to JVM spec. $5.4.3c & $5.4.3d

// Look up method in klasses, including static methods
// Then look up local default methods
Method* LinkResolver::lookup_method_in_klasses(const LinkInfo& link_info,
                                               bool checkpolymorphism,
                                               bool in_imethod_resolve) {
  NoSafepointVerifier nsv;  // Method* returned may not be reclaimed

  Klass* klass = link_info.resolved_klass();
  Symbol* name = link_info.name();
  Symbol* signature = link_info.signature();

  // Ignore overpasses so statics can be found during resolution
  Method* result = klass->uncached_lookup_method(name, signature, Klass::OverpassLookupMode::skip);

  if (klass->is_array_klass()) {
    // Only consider klass and super klass for arrays
    return result;
  }

  InstanceKlass* ik = InstanceKlass::cast(klass);

  // JDK 8, JVMS 5.4.3.4: Interface method resolution should
  // ignore static and non-public methods of java.lang.Object,
  // like clone and finalize.
  if (in_imethod_resolve &&
      result != nullptr &&
      ik->is_interface() &&
      (result->is_static() || !result->is_public()) &&
      result->method_holder() == vmClasses::Object_klass()) {
    result = nullptr;
  }

  // Before considering default methods, check for an overpass in the
  // current class if a method has not been found.
  if (result == nullptr) {
    result = ik->find_method(name, signature);
  }

  if (result == nullptr) {
    Array<Method*>* default_methods = ik->default_methods();
    if (default_methods != nullptr) {
      result = InstanceKlass::find_method(default_methods, name, signature);
    }
  }

  if (checkpolymorphism && result != nullptr) {
    vmIntrinsics::ID iid = result->intrinsic_id();
    if (MethodHandles::is_signature_polymorphic(iid)) {
      // Do not link directly to these.  The VM must produce a synthetic one using lookup_polymorphic_method.
      return nullptr;
    }
  }
  return result;
}

// returns first instance method
// Looks up method in classes, then looks up local default methods
Method* LinkResolver::lookup_instance_method_in_klasses(Klass* klass,
                                                        Symbol* name,
                                                        Symbol* signature,
                                                        Klass::PrivateLookupMode private_mode) {
  Method* result = klass->uncached_lookup_method(name, signature, Klass::OverpassLookupMode::find, private_mode);

  while (result != nullptr && result->is_static() && result->method_holder()->super() != nullptr) {
    Klass* super_klass = result->method_holder()->super();
    result = super_klass->uncached_lookup_method(name, signature, Klass::OverpassLookupMode::find, private_mode);
  }

  if (klass->is_array_klass()) {
    // Only consider klass and super klass for arrays
    return result;
  }

  if (result == nullptr) {
    Array<Method*>* default_methods = InstanceKlass::cast(klass)->default_methods();
    if (default_methods != nullptr) {
      result = InstanceKlass::find_method(default_methods, name, signature);
      assert(result == nullptr || !result->is_static(), "static defaults not allowed");
    }
  }
  return result;
}

int LinkResolver::vtable_index_of_interface_method(Klass* klass, const methodHandle& resolved_method) {
  InstanceKlass* ik = InstanceKlass::cast(klass);
  return ik->vtable_index_of_interface_method(resolved_method());
}

Method* LinkResolver::lookup_method_in_interfaces(const LinkInfo& cp_info) {
  InstanceKlass *ik = InstanceKlass::cast(cp_info.resolved_klass());

  // Specify 'true' in order to skip default methods when searching the
  // interfaces.  Function lookup_method_in_klasses() already looked for
  // the method in the default methods table.
  return ik->lookup_method_in_all_interfaces(cp_info.name(), cp_info.signature(), Klass::DefaultsLookupMode::skip);
}

Method* LinkResolver::lookup_polymorphic_method(const LinkInfo& link_info,
                                                Handle *appendix_result_or_null,
                                                TRAPS) {
  ResourceMark rm(THREAD);
  Klass* klass = link_info.resolved_klass();
  Symbol* name = link_info.name();
  Symbol* full_signature = link_info.signature();
  LogTarget(Info, methodhandles) lt_mh;

  vmIntrinsics::ID iid = MethodHandles::signature_polymorphic_name_id(name);
  log_info(methodhandles)("lookup_polymorphic_method iid=%s %s.%s%s",
                          vmIntrinsics::name_at(iid), klass->external_name(),
                          name->as_C_string(), full_signature->as_C_string());
  if ((klass == vmClasses::MethodHandle_klass() ||
       klass == vmClasses::VarHandle_klass()) &&
      iid != vmIntrinsics::_none) {
    if (MethodHandles::is_signature_polymorphic_intrinsic(iid)) {
      // Most of these do not need an up-call to Java to resolve, so can be done anywhere.
      // Do not erase last argument type (MemberName) if it is a static linkTo method.
      bool keep_last_arg = MethodHandles::is_signature_polymorphic_static(iid);
      TempNewSymbol basic_signature =
        MethodHandles::lookup_basic_type_signature(full_signature, keep_last_arg);
      log_info(methodhandles)("lookup_polymorphic_method %s %s => basic %s",
                              name->as_C_string(),
                              full_signature->as_C_string(),
                              basic_signature->as_C_string());
      Method* result = SystemDictionary::find_method_handle_intrinsic(iid,
                                                              basic_signature,
                                                              CHECK_NULL);
      if (result != nullptr) {
        assert(result->is_method_handle_intrinsic(), "MH.invokeBasic or MH.linkTo* intrinsic");
        assert(result->intrinsic_id() != vmIntrinsics::_invokeGeneric, "wrong place to find this");
        assert(basic_signature == result->signature(), "predict the result signature");
        if (lt_mh.is_enabled()) {
          LogStream ls(lt_mh);
          ls.print("lookup_polymorphic_method => intrinsic ");
          result->print_on(&ls);
        }
      }
      return result;
    } else if (iid == vmIntrinsics::_invokeGeneric
               && THREAD->can_call_java()
               && appendix_result_or_null != nullptr) {
      // This is a method with type-checking semantics.
      // We will ask Java code to spin an adapter method for it.
      if (!MethodHandles::enabled()) {
        // Make sure the Java part of the runtime has been booted up.
        Klass* natives = vmClasses::MethodHandleNatives_klass();
        if (natives == nullptr || InstanceKlass::cast(natives)->is_not_initialized()) {
          SystemDictionary::resolve_or_fail(vmSymbols::java_lang_invoke_MethodHandleNatives(),
                                            Handle(),
                                            true,
                                            CHECK_NULL);
        }
      }

      Handle appendix;
      Method* result = SystemDictionary::find_method_handle_invoker(klass,
                                                                    name,
                                                                    full_signature,
                                                                    link_info.current_klass(),
                                                                    &appendix,
                                                                    CHECK_NULL);
      if (lt_mh.is_enabled()) {
        LogStream ls(lt_mh);
        ls.print("lookup_polymorphic_method => (via Java) ");
        result->print_on(&ls);
        ls.print("  lookup_polymorphic_method => appendix = ");
        appendix.is_null() ? ls.print_cr("(none)") : appendix->print_on(&ls);
      }
      if (result != nullptr) {
#ifdef ASSERT
        ResourceMark rm(THREAD);

        TempNewSymbol basic_signature =
          MethodHandles::lookup_basic_type_signature(full_signature);
        int actual_size_of_params = result->size_of_parameters();
        int expected_size_of_params = ArgumentSizeComputer(basic_signature).size();
        // +1 for MethodHandle.this, +1 for trailing MethodType
        if (!MethodHandles::is_signature_polymorphic_static(iid))  expected_size_of_params += 1;
        if (appendix.not_null())                                   expected_size_of_params += 1;
        if (actual_size_of_params != expected_size_of_params) {
          tty->print_cr("*** basic_signature=%s", basic_signature->as_C_string());
          tty->print_cr("*** result for %s: ", vmIntrinsics::name_at(iid));
          result->print();
        }
        assert(actual_size_of_params == expected_size_of_params,
               "%d != %d", actual_size_of_params, expected_size_of_params);
#endif //ASSERT

        assert(appendix_result_or_null != nullptr, "");
        (*appendix_result_or_null) = appendix;
      }
      return result;
    }
  }
  return nullptr;
}

static void print_nest_host_error_on(stringStream* ss, Klass* ref_klass, Klass* sel_klass) {
  assert(ref_klass->is_instance_klass(), "must be");
  assert(sel_klass->is_instance_klass(), "must be");
  InstanceKlass* ref_ik = InstanceKlass::cast(ref_klass);
  InstanceKlass* sel_ik = InstanceKlass::cast(sel_klass);
  const char* nest_host_error_1 = ref_ik->nest_host_error();
  const char* nest_host_error_2 = sel_ik->nest_host_error();
  if (nest_host_error_1 != nullptr || nest_host_error_2 != nullptr) {
    ss->print(", (%s%s%s)",
              (nest_host_error_1 != nullptr) ? nest_host_error_1 : "",
              (nest_host_error_1 != nullptr && nest_host_error_2 != nullptr) ? ", " : "",
              (nest_host_error_2 != nullptr) ? nest_host_error_2 : "");
  }
}

void LinkResolver::check_method_accessability(Klass* ref_klass,
                                              Klass* resolved_klass,
                                              Klass* sel_klass,
                                              const methodHandle& sel_method,
                                              TRAPS) {

  AccessFlags flags = sel_method->access_flags();

  // Special case:  arrays always override "clone". JVMS 2.15.
  // If the resolved klass is an array class, and the declaring class
  // is java.lang.Object and the method is "clone", set the flags
  // to public.
  //
  // We'll check for the method name first, as that's most likely
  // to be false (so we'll short-circuit out of these tests).
  if (sel_method->name() == vmSymbols::clone_name() &&
      sel_klass == vmClasses::Object_klass() &&
      resolved_klass->is_array_klass()) {
    // We need to change "protected" to "public".
    assert(flags.is_protected(), "clone not protected?");
    u2 new_flags = flags.as_method_flags();
    new_flags = new_flags & (~JVM_ACC_PROTECTED);
    new_flags = new_flags | JVM_ACC_PUBLIC;
    flags.set_flags(new_flags);
  }
//  assert(extra_arg_result_or_null != nullptr, "must be able to return extra argument");

  bool can_access = Reflection::verify_member_access(ref_klass,
                                                     resolved_klass,
                                                     sel_klass,
                                                     flags,
                                                     true, false, CHECK);
  // Any existing exceptions that may have been thrown
  // have been allowed to propagate.
  if (!can_access) {
    ResourceMark rm(THREAD);
    stringStream ss;
    bool same_module = (sel_klass->module() == ref_klass->module());
    ss.print("class %s tried to access %s%s%smethod '%s' (%s%s%s)",
             ref_klass->external_name(),
             sel_method->is_abstract()  ? "abstract "  : "",
             sel_method->is_protected() ? "protected " : "",
             sel_method->is_private()   ? "private "   : "",
             sel_method->external_name(),
             (same_module) ? ref_klass->joint_in_module_of_loader(sel_klass) : ref_klass->class_in_module_of_loader(),
             (same_module) ? "" : "; ",
             (same_module) ? "" : sel_klass->class_in_module_of_loader()
             );

    // For private access see if there was a problem with nest host
    // resolution, and if so report that as part of the message.
    if (sel_method->is_private()) {
      print_nest_host_error_on(&ss, ref_klass, sel_klass);
    }

    // Names are all known to be < 64k so we know this formatted message is not excessively large.
    Exceptions::fthrow(THREAD_AND_LOCATION,
                       vmSymbols::java_lang_IllegalAccessError(),
                       "%s",
                       ss.as_string()
                       );
    return;
  }
}

void LinkResolver::resolve_continuation_enter(CallInfo& callinfo, TRAPS) {
  Klass* resolved_klass = vmClasses::Continuation_klass();
  Symbol* method_name = vmSymbols::enter_name();
  Symbol* method_signature = vmSymbols::continuationEnter_signature();
  Klass*  current_klass = resolved_klass;
  LinkInfo link_info(resolved_klass, method_name, method_signature, current_klass);
  Method* resolved_method = resolve_method(link_info, Bytecodes::_invokestatic, CHECK);
  callinfo.set_static(resolved_klass, methodHandle(THREAD, resolved_method), CHECK);
}

Method* LinkResolver::resolve_method_statically(Bytecodes::Code code,
                                                const constantPoolHandle& pool, int index, TRAPS) {
  // This method is used only
  // (1) in C2 from InlineTree::ok_to_inline (via ciMethod::check_call),
  // and
  // (2) in Bytecode_invoke::static_target
  // It appears to fail when applied to an invokeinterface call site.
  // FIXME: Remove this method and ciMethod::check_call; refactor to use the other LinkResolver entry points.
  // resolve klass
  if (code == Bytecodes::_invokedynamic) {
    Klass* resolved_klass = vmClasses::MethodHandle_klass();
    Symbol* method_name = vmSymbols::invoke_name();
    Symbol* method_signature = pool->signature_ref_at(index, code);
    Klass*  current_klass = pool->pool_holder();
    LinkInfo link_info(resolved_klass, method_name, method_signature, current_klass);
    return resolve_method(link_info, code, THREAD);
  }

  LinkInfo link_info(pool, index, methodHandle(), code, CHECK_NULL);
  Klass* resolved_klass = link_info.resolved_klass();

  if (pool->has_preresolution()
      || ((resolved_klass == vmClasses::MethodHandle_klass() || resolved_klass == vmClasses::VarHandle_klass()) &&
          MethodHandles::is_signature_polymorphic_name(resolved_klass, link_info.name()))) {
    Method* result = ConstantPool::method_at_if_loaded(pool, index);
    if (result != nullptr) {
      return result;
    }
  }

  if (code == Bytecodes::_invokeinterface) {
    return resolve_interface_method(link_info, code, THREAD);
  } else if (code == Bytecodes::_invokevirtual) {
    return resolve_method(link_info, code, THREAD);
  } else if (!resolved_klass->is_interface()) {
    return resolve_method(link_info, code, THREAD);
  } else {
    return resolve_interface_method(link_info, code, THREAD);
  }
}

// Check and print a loader constraint violation message for method or interface method
void LinkResolver::check_method_loader_constraints(const LinkInfo& link_info,
                                                   const methodHandle& resolved_method,
                                                   const char* method_type, TRAPS) {
  Handle current_loader(THREAD, link_info.current_klass()->class_loader());
  Handle resolved_loader(THREAD, resolved_method->method_holder()->class_loader());

  ResourceMark rm(THREAD);
  Symbol* failed_type_symbol =
    SystemDictionary::check_signature_loaders(link_info.signature(),
                                              /*klass_being_linked*/ nullptr, // We are not linking class
                                              current_loader,
                                              resolved_loader, true);
  if (failed_type_symbol != nullptr) {
    Klass* current_class = link_info.current_klass();
    ClassLoaderData* current_loader_data = current_class->class_loader_data();
    assert(current_loader_data != nullptr, "current class has no class loader data");
    Klass* resolved_method_class = resolved_method->method_holder();
    ClassLoaderData* target_loader_data = resolved_method_class->class_loader_data();
    assert(target_loader_data != nullptr, "resolved method's class has no class loader data");

    stringStream ss;
    ss.print("loader constraint violation: when resolving %s '", method_type);
    Method::print_external_name(&ss, link_info.resolved_klass(), link_info.name(), link_info.signature());
    ss.print("' the class loader %s of the current class, %s,"
             " and the class loader %s for the method's defining class, %s, have"
             " different Class objects for the type %s used in the signature (%s; %s)",
             current_loader_data->loader_name_and_id(),
             current_class->name()->as_C_string(),
             target_loader_data->loader_name_and_id(),
             resolved_method_class->name()->as_C_string(),
             failed_type_symbol->as_C_string(),
             current_class->class_in_module_of_loader(false, true),
             resolved_method_class->class_in_module_of_loader(false, true));
    THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
  }
}

void LinkResolver::check_field_loader_constraints(Symbol* field, Symbol* sig,
                                                  Klass* current_klass,
                                                  Klass* sel_klass, TRAPS) {
  Handle ref_loader(THREAD, current_klass->class_loader());
  Handle sel_loader(THREAD, sel_klass->class_loader());

  ResourceMark rm(THREAD);  // needed for check_signature_loaders
  Symbol* failed_type_symbol =
    SystemDictionary::check_signature_loaders(sig,
                                              /*klass_being_linked*/ nullptr, // We are not linking class
                                              ref_loader, sel_loader,
                                              false);
  if (failed_type_symbol != nullptr) {
    stringStream ss;
    const char* failed_type_name = failed_type_symbol->as_klass_external_name();

    ss.print("loader constraint violation: when resolving field \"%s\" of type %s, "
             "the class loader %s of the current class, %s, "
             "and the class loader %s for the field's defining %s, %s, "
             "have different Class objects for type %s (%s; %s)",
             field->as_C_string(),
             failed_type_name,
             current_klass->class_loader_data()->loader_name_and_id(),
             current_klass->external_name(),
             sel_klass->class_loader_data()->loader_name_and_id(),
             sel_klass->external_kind(),
             sel_klass->external_name(),
             failed_type_name,
             current_klass->class_in_module_of_loader(false, true),
             sel_klass->class_in_module_of_loader(false, true));
    THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
  }
}

Method* LinkResolver::resolve_method(const LinkInfo& link_info,
                                     Bytecodes::Code code, TRAPS) {

  Handle nested_exception;
  Klass* resolved_klass = link_info.resolved_klass();

  // 1. For invokevirtual, cannot call an interface method
  if (code == Bytecodes::_invokevirtual && resolved_klass->is_interface()) {
    ResourceMark rm(THREAD);
    char buf[200];
    jio_snprintf(buf, sizeof(buf), "Found interface %s, but class was expected",
        resolved_klass->external_name());
    THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), buf);
  }

  // 2. check constant pool tag for called method - must be JVM_CONSTANT_Methodref
  if (!link_info.tag().is_invalid() && !link_info.tag().is_method()) {
    ResourceMark rm(THREAD);
    stringStream ss;
    ss.print("Method '");
    Method::print_external_name(&ss, link_info.resolved_klass(), link_info.name(), link_info.signature());
    ss.print("' must be Methodref constant");
    THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), ss.as_string());
  }

  // 3. lookup method in resolved klass and its super klasses
  methodHandle resolved_method(THREAD, lookup_method_in_klasses(link_info, true, false));

  // 4. lookup method in all the interfaces implemented by the resolved klass
  if (resolved_method.is_null() && !resolved_klass->is_array_klass()) { // not found in the class hierarchy
    resolved_method = methodHandle(THREAD, lookup_method_in_interfaces(link_info));

    if (resolved_method.is_null()) {
      // JSR 292:  see if this is an implicitly generated method MethodHandle.linkToVirtual(*...), etc
      Method* method = lookup_polymorphic_method(link_info, (Handle*)nullptr, THREAD);
      resolved_method = methodHandle(THREAD, method);
      if (HAS_PENDING_EXCEPTION) {
        nested_exception = Handle(THREAD, PENDING_EXCEPTION);
        CLEAR_PENDING_EXCEPTION;
      }
    }
  }

  // 5. method lookup failed
  if (resolved_method.is_null()) {
    ResourceMark rm(THREAD);
    stringStream ss;
    ss.print("'");
    Method::print_external_name(&ss, resolved_klass, link_info.name(), link_info.signature());
    ss.print("'");
    THROW_MSG_CAUSE_(vmSymbols::java_lang_NoSuchMethodError(),
                     ss.as_string(), nested_exception, nullptr);
  }

  // 6. access checks, access checking may be turned off when calling from within the VM.
  Klass* current_klass = link_info.current_klass();
  if (link_info.check_access()) {
    assert(current_klass != nullptr , "current_klass should not be null");

    // check if method can be accessed by the referring class
    check_method_accessability(current_klass,
                               resolved_klass,
                               resolved_method->method_holder(),
                               resolved_method,
                               CHECK_NULL);
  }
  if (link_info.check_loader_constraints()) {
    // check loader constraints
    check_method_loader_constraints(link_info, resolved_method, "method", CHECK_NULL);
  }

  return resolved_method();
}

static void trace_method_resolution(const char* prefix,
                                    Klass* klass,
                                    Klass* resolved_klass,
                                    Method* method,
                                    bool logitables,
                                    int index = -1) {
#ifndef PRODUCT
  ResourceMark rm;
  Log(itables) logi;
  LogStream lsi(logi.trace());
  Log(vtables) logv;
  LogStream lsv(logv.trace());
  outputStream* st;
  if (logitables) {
    st = &lsi;
  } else {
    st = &lsv;
  }
  st->print("%s%s, compile-time-class:%s, method:%s, method_holder:%s, access_flags: ",
            prefix,
            (klass == nullptr ? "<null>" : klass->internal_name()),
            resolved_klass->internal_name(),
            Method::name_and_sig_as_C_string(resolved_klass,
                                             method->name(),
                                             method->signature()),
            method->method_holder()->internal_name());
  method->print_linkage_flags(st);
  if (index != -1) {
    st->print("vtable_index:%d", index);
  }
  st->cr();
#endif // PRODUCT
}

// Do linktime resolution of a method in the interface within the context of the specified bytecode.
Method* LinkResolver::resolve_interface_method(const LinkInfo& link_info, Bytecodes::Code code, TRAPS) {

  Klass* resolved_klass = link_info.resolved_klass();

  // check if klass is interface
  if (!resolved_klass->is_interface()) {
    ResourceMark rm(THREAD);
    char buf[200];
    jio_snprintf(buf, sizeof(buf), "Found class %s, but interface was expected", resolved_klass->external_name());
    THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), buf);
  }

  // check constant pool tag for called method - must be JVM_CONSTANT_InterfaceMethodref
  if (!link_info.tag().is_invalid() && !link_info.tag().is_interface_method()) {
    ResourceMark rm(THREAD);
    stringStream ss;
    ss.print("Method '");
    Method::print_external_name(&ss, link_info.resolved_klass(), link_info.name(), link_info.signature());
    ss.print("' must be InterfaceMethodref constant");
    THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), ss.as_string());
  }

  // lookup method in this interface or its super, java.lang.Object
  // JDK8: also look for static methods
  methodHandle resolved_method(THREAD, lookup_method_in_klasses(link_info, false, true));

  if (resolved_method.is_null() && !resolved_klass->is_array_klass()) {
    // lookup method in all the super-interfaces
    resolved_method = methodHandle(THREAD, lookup_method_in_interfaces(link_info));
  }

  if (resolved_method.is_null()) {
    // no method found
    ResourceMark rm(THREAD);
    stringStream ss;
    ss.print("'");
    Method::print_external_name(&ss, resolved_klass, link_info.name(), link_info.signature());
    ss.print("'");
    THROW_MSG_NULL(vmSymbols::java_lang_NoSuchMethodError(), ss.as_string());
  }

  if (link_info.check_access()) {
    // JDK8 adds non-public interface methods, and accessability check requirement
    Klass* current_klass = link_info.current_klass();

    assert(current_klass != nullptr , "current_klass should not be null");

    // check if method can be accessed by the referring class
    check_method_accessability(current_klass,
                               resolved_klass,
                               resolved_method->method_holder(),
                               resolved_method,
                               CHECK_NULL);
  }
  if (link_info.check_loader_constraints()) {
    check_method_loader_constraints(link_info, resolved_method, "interface method", CHECK_NULL);
  }

  if (code != Bytecodes::_invokestatic && resolved_method->is_static()) {
    ResourceMark rm(THREAD);
    stringStream ss;
    ss.print("Expected instance not static method '");
    Method::print_external_name(&ss, resolved_klass,
                                resolved_method->name(), resolved_method->signature());
    ss.print("'");
    THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), ss.as_string());
  }

  if (log_develop_is_enabled(Trace, itables)) {
    char buf[200];
    jio_snprintf(buf, sizeof(buf), "%s resolved interface method: caller-class:",
                 Bytecodes::name(code));
    trace_method_resolution(buf, link_info.current_klass(), resolved_klass, resolved_method(), true);
  }

  return resolved_method();
}

//------------------------------------------------------------------------------------------------------------------------
// Field resolution

void LinkResolver::check_field_accessability(Klass* ref_klass,
                                             Klass* resolved_klass,
                                             Klass* sel_klass,
                                             const fieldDescriptor& fd,
                                             TRAPS) {
  bool can_access = Reflection::verify_member_access(ref_klass,
                                                     resolved_klass,
                                                     sel_klass,
                                                     fd.access_flags(),
                                                     true, false, CHECK);
  // Any existing exceptions that may have been thrown, for example LinkageErrors
  // from nest-host resolution, have been allowed to propagate.
  if (!can_access) {
    bool same_module = (sel_klass->module() == ref_klass->module());
    ResourceMark rm(THREAD);
    stringStream ss;
    ss.print("class %s tried to access %s%sfield %s.%s (%s%s%s)",
             ref_klass->external_name(),
             fd.is_protected() ? "protected " : "",
             fd.is_private()   ? "private "   : "",
             sel_klass->external_name(),
             fd.name()->as_C_string(),
             (same_module) ? ref_klass->joint_in_module_of_loader(sel_klass) : ref_klass->class_in_module_of_loader(),
             (same_module) ? "" : "; ",
             (same_module) ? "" : sel_klass->class_in_module_of_loader()
             );
    // For private access see if there was a problem with nest host
    // resolution, and if so report that as part of the message.
    if (fd.is_private()) {
      print_nest_host_error_on(&ss, ref_klass, sel_klass);
    }
    // Names are all known to be < 64k so we know this formatted message is not excessively large.
    Exceptions::fthrow(THREAD_AND_LOCATION,
                       vmSymbols::java_lang_IllegalAccessError(),
                       "%s",
                       ss.as_string()
                       );
    return;
  }
}

void LinkResolver::resolve_field_access(fieldDescriptor& fd,
                                        const constantPoolHandle& pool,
                                        int index,
                                        const methodHandle& method,
                                        Bytecodes::Code byte,
                                        bool initialize_class, TRAPS) {
  LinkInfo link_info(pool, index, method, byte, CHECK);
  resolve_field(fd, link_info, byte, initialize_class, CHECK);
}

void LinkResolver::resolve_field(fieldDescriptor& fd,
                                 const LinkInfo& link_info,
                                 Bytecodes::Code byte, bool initialize_class,
                                 TRAPS) {
  assert(byte == Bytecodes::_getstatic || byte == Bytecodes::_putstatic ||
         byte == Bytecodes::_getfield  || byte == Bytecodes::_putfield  ||
         byte == Bytecodes::_nofast_getfield  || byte == Bytecodes::_nofast_putfield  ||