001/*
002 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 *  This file is licensed to You under the Eclipse Public License (EPL);
005 *  You may not use this file except in compliance with the License. You
006 *  may obtain a copy of the License at
007 *
008 *      http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 *  See the COPYRIGHT.txt file distributed with this work for information
011 *  regarding copyright ownership.
012 */
013package org.jikesrvm.ia32;
014
015import static org.jikesrvm.ia32.BaselineConstants.STACKFRAME_FIRST_PARAMETER_OFFSET;
016import static org.jikesrvm.ia32.RegisterConstants.NUM_PARAMETER_GPRS;
017
018import org.jikesrvm.VM;
019import org.jikesrvm.runtime.Magic;
020import org.vmmagic.pragma.NoInline;
021import org.vmmagic.pragma.Uninterruptible;
022import org.vmmagic.unboxed.Address;
023
024/**
025 * Machine specific helper functions for dynamic linking.
026 */
027@Uninterruptible
028public abstract class DynamicLinkerHelper {
029
030  /**
031   * Reach up two stack frames into a frame that is compiled
032   * with the DynamicBridge register protocol and grab
033   * the receiver object of the invoke (ie the first param).
034   * NOTE: assumes that caller has disabled GC.
035   *
036   * @return the receiver object for the method invocation
037   */
038  @NoInline
039  public static Object getReceiverObject() {
040    Address callingFrame = Magic.getCallerFramePointer(Magic.getFramePointer());
041    callingFrame = Magic.getCallerFramePointer(callingFrame);
042    Address location = Address.zero();
043    if (0 < NUM_PARAMETER_GPRS) {
044      location = callingFrame.plus(STACKFRAME_FIRST_PARAMETER_OFFSET).loadAddress();
045
046    } else {
047      VM.sysFail("DynamicLinerHelper: assumes at least one param passed in registers");
048    }
049    return Magic.addressAsObject(location);
050  }
051}