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Java example source code file (methodHandles_zero.cpp)

This example Java source code file (methodHandles_zero.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

instanceklass\:\:cast, interpreterframe, interpretergenerator\:\:generate_entry_impl, javathread, klass, method, methodhandles\:\:method_handle_entry_invalid, methodhandles\:\:method_handle_entry_invokebasic, methodhandles\:\:method_handle_entry_linktovirtual, shouldnotreachhere, stack_object, thread, traps, unused

The methodHandles_zero.cpp Java example source code

/*
 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2009, 2010, 2011 Red Hat, Inc.
 * 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 "precompiled.hpp"
#include "interpreter/interpreterGenerator.hpp"
#include "interpreter/interpreter.hpp"
#include "memory/allocation.inline.hpp"
#include "prims/methodHandles.hpp"

void MethodHandles::invoke_target(Method* method, TRAPS) {

  JavaThread *thread = (JavaThread *) THREAD;
  ZeroStack *stack = thread->zero_stack();
  InterpreterFrame *frame = thread->top_zero_frame()->as_interpreter_frame();
  interpreterState istate = frame->interpreter_state();

  // Trim back the stack to put the parameters at the top
  stack->set_sp(istate->stack() + 1);

  Interpreter::invoke_method(method, method->from_interpreted_entry(), THREAD);

  // Convert the result
  istate->set_stack(stack->sp() - 1);

}

oop MethodHandles::popFromStack(TRAPS) {

  JavaThread *thread = (JavaThread *) THREAD;
  InterpreterFrame *frame = thread->top_zero_frame()->as_interpreter_frame();
  interpreterState istate = frame->interpreter_state();
  intptr_t* topOfStack = istate->stack();

  oop top = STACK_OBJECT(-1);
  MORE_STACK(-1);
  istate->set_stack(topOfStack);

  return top;

}

int MethodHandles::method_handle_entry_invokeBasic(Method* method, intptr_t UNUSED, TRAPS) {

  JavaThread *thread = (JavaThread *) THREAD;
  InterpreterFrame *frame = thread->top_zero_frame()->as_interpreter_frame();
  interpreterState istate = frame->interpreter_state();
  intptr_t* topOfStack = istate->stack();

  // 'this' is a MethodHandle. We resolve the target method by accessing this.form.vmentry.vmtarget.
  int numArgs = method->size_of_parameters();
  oop lform1 = java_lang_invoke_MethodHandle::form(STACK_OBJECT(-numArgs)); // this.form
  oop vmEntry1 = java_lang_invoke_LambdaForm::vmentry(lform1);
  Method* vmtarget = (Method*) java_lang_invoke_MemberName::vmtarget(vmEntry1);

  invoke_target(vmtarget, THREAD);

  // No deoptimized frames on the stack
  return 0;
}

int MethodHandles::method_handle_entry_linkToStaticOrSpecial(Method* method, intptr_t UNUSED, TRAPS) {

  // Pop appendix argument from stack. This is a MemberName which we resolve to the
  // target method.
  oop vmentry = popFromStack(THREAD);

  Method* vmtarget = (Method*) java_lang_invoke_MemberName::vmtarget(vmentry);

  invoke_target(vmtarget, THREAD);

  return 0;
}

int MethodHandles::method_handle_entry_linkToInterface(Method* method, intptr_t UNUSED, TRAPS) {
  JavaThread *thread = (JavaThread *) THREAD;
  InterpreterFrame *frame = thread->top_zero_frame()->as_interpreter_frame();
  interpreterState istate = frame->interpreter_state();

  // Pop appendix argument from stack. This is a MemberName which we resolve to the
  // target method.
  oop vmentry = popFromStack(THREAD);
  intptr_t* topOfStack = istate->stack();

  // Resolve target method by looking up in the receiver object's itable.
  Klass* clazz = java_lang_Class::as_Klass(java_lang_invoke_MemberName::clazz(vmentry));
  intptr_t vmindex = java_lang_invoke_MemberName::vmindex(vmentry);
  Method* target = (Method*) java_lang_invoke_MemberName::vmtarget(vmentry);

  int numArgs = target->size_of_parameters();
  oop recv = STACK_OBJECT(-numArgs);

  InstanceKlass* klass_part = InstanceKlass::cast(recv->klass());
  itableOffsetEntry* ki = (itableOffsetEntry*) klass_part->start_of_itable();
  int i;
  for ( i = 0 ; i < klass_part->itable_length() ; i++, ki++ ) {
    if (ki->interface_klass() == clazz) break;
  }

  itableMethodEntry* im = ki->first_method_entry(recv->klass());
  Method* vmtarget = im[vmindex].method();

  invoke_target(vmtarget, THREAD);

  return 0;
}

int MethodHandles::method_handle_entry_linkToVirtual(Method* method, intptr_t UNUSED, TRAPS) {
  JavaThread *thread = (JavaThread *) THREAD;

  InterpreterFrame *frame = thread->top_zero_frame()->as_interpreter_frame();
  interpreterState istate = frame->interpreter_state();

  // Pop appendix argument from stack. This is a MemberName which we resolve to the
  // target method.
  oop vmentry = popFromStack(THREAD);
  intptr_t* topOfStack = istate->stack();

  // Resolve target method by looking up in the receiver object's vtable.
  intptr_t vmindex = java_lang_invoke_MemberName::vmindex(vmentry);
  Method* target = (Method*) java_lang_invoke_MemberName::vmtarget(vmentry);
  int numArgs = target->size_of_parameters();
  oop recv = STACK_OBJECT(-numArgs);
  Klass* clazz = recv->klass();
  Klass* klass_part = InstanceKlass::cast(clazz);
  klassVtable* vtable = klass_part->vtable();
  Method* vmtarget = vtable->method_at(vmindex);

  invoke_target(vmtarget, THREAD);

  return 0;
}

int MethodHandles::method_handle_entry_invalid(Method* method, intptr_t UNUSED, TRAPS) {
  ShouldNotReachHere();
  return 0;
}

address MethodHandles::generate_method_handle_interpreter_entry(MacroAssembler* masm,
                                                                vmIntrinsics::ID iid) {
  switch (iid) {
  case vmIntrinsics::_invokeGeneric:
  case vmIntrinsics::_compiledLambdaForm:
    // Perhaps surprisingly, the symbolic references visible to Java are not directly used.
    // They are linked to Java-generated adapters via MethodHandleNatives.linkMethod.
    // They all allow an appendix argument.
    return InterpreterGenerator::generate_entry_impl(masm, (address) MethodHandles::method_handle_entry_invalid);
  case vmIntrinsics::_invokeBasic:
    return InterpreterGenerator::generate_entry_impl(masm, (address) MethodHandles::method_handle_entry_invokeBasic);
  case vmIntrinsics::_linkToStatic:
  case vmIntrinsics::_linkToSpecial:
    return InterpreterGenerator::generate_entry_impl(masm, (address) MethodHandles::method_handle_entry_linkToStaticOrSpecial);
  case vmIntrinsics::_linkToInterface:
    return InterpreterGenerator::generate_entry_impl(masm, (address) MethodHandles::method_handle_entry_linkToInterface);
  case vmIntrinsics::_linkToVirtual:
    return InterpreterGenerator::generate_entry_impl(masm, (address) MethodHandles::method_handle_entry_linkToVirtual);
  default:
    ShouldNotReachHere();
    return NULL;
  }
}

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