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;
  }
}