Registers.java

/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
package org.jikesrvm.ia32;

import org.jikesrvm.runtime.ArchEntrypoints;
import org.jikesrvm.runtime.Magic;
import org.jikesrvm.scheduler.RVMThread;
import org.jikesrvm.VM;
import org.jikesrvm.mm.mminterface.MemoryManager;
import org.vmmagic.pragma.NonMoving;
import org.vmmagic.pragma.Uninterruptible;
import org.vmmagic.pragma.Untraced;
import org.vmmagic.unboxed.Address;
import org.vmmagic.unboxed.Word;
import org.vmmagic.unboxed.Offset;
import org.vmmagic.unboxed.WordArray;

/**
 * The machine state comprising a thread's execution context, used both for
 * thread context switching and for software/hardware exception
 * reporting/delivery.
 */
@Uninterruptible
@NonMoving
public abstract class Registers implements RegisterConstants {

  /** General purpose registers */
  @Untraced
  public final WordArray gprs;
  /** Floating point registers */
  @Untraced
  public final double[] fprs;
  public final WordArray gprsShadow;
  public final double[] fprsShadow;
  /** Instruction address register */
  public Address ip;
  /** Frame pointer */
  public Address fp;

  /**
   * Do exception registers currently contain live values? Set by C hardware
   * exception handler and RuntimeEntrypoints.athrow and reset by each
   * implementation of ExceptionDeliverer.deliverException
   */
  public boolean inuse;

  public Registers() {
    gprs = gprsShadow = MemoryManager.newNonMovingWordArray(NUM_GPRS);
    fprs = fprsShadow = MemoryManager.newNonMovingDoubleArray(NUM_FPRS);
  }
  public final void copyFrom(Registers other) {
    for (int i=0;i<NUM_GPRS;++i) {
      gprs.set(i,other.gprs.get(i));
    }
    for (int i=0;i<NUM_FPRS;++i) {
      fprs[i]=other.fprs[i];
    }
    ip=other.ip;
    fp=other.fp;
  }
  public final void clear() {
    for (int i=0;i<NUM_GPRS;++i) {
      gprs.set(i,Word.zero());
    }
    for (int i=0;i<NUM_FPRS;++i) {
      fprs[i]=0.;
    }
    ip=Address.zero();
    fp=Address.zero();
  }
  public final void assertSame(Registers other) {
    boolean fail=false;
    for (int i=0;i<NUM_GPRS;++i) {
      if (gprs.get(i).NE(other.gprs.get(i))) {
        VM.sysWriteln("Registers not equal: GPR #",i);
        fail=true;
      }
    }
    for (int i=0;i<NUM_FPRS;++i) {
      if (fprs[i]!=other.fprs[i]) {
        VM.sysWriteln("Registers not equal: FPR #",i);
        fail=true;
      }
    }
    if (ip.NE(other.ip)) {
      VM.sysWriteln("Registers not equal: IP");
      fail=true;
    }
    if (fp.NE(other.fp)) {
      VM.sysWriteln("Registers not equal: FP");
      fail=true;
    }
    if (fail) {
      RVMThread.dumpStack();
      VM.sysFail("Registers.assertSame() failed");
    }
  }

  /**
   * Return framepointer for the deepest stackframe
   */
  public final Address getInnermostFramePointer() {
    return fp;
  }

  /**
   * Return next instruction address for the deepest stackframe
   */
  public final Address getInnermostInstructionAddress() {
    return ip;
  }

  /**
   * update the machine state as if the stackframe were unwound.
   */
  public final void unwindStackFrame() {
    ip = Magic.getReturnAddress(fp);
    fp = Magic.getCallerFramePointer(fp);
  }

  /**
   * set ip & fp. used to control the stack frame at which a scan of
   * the stack during GC will start, for ex., the top java frame for
   * a thread that is blocked in native code during GC.
   */
  public final void setInnermost(Address newip, Address newfp) {
    ip = newip;
    fp = newfp;
  }

  /**
   * set ip and fp values to those of the caller. used just prior to entering
   * sigwait to set fp & ip so that GC will scan the threads stack
   * starting at the frame of the method that called sigwait.
   */
  public final void setInnermost() {
    Address current_fp = Magic.getFramePointer();
    ip = Magic.getReturnAddress(current_fp);
    fp = Magic.getCallerFramePointer(current_fp);
  }

  public final Address getIPLocation() {
    Offset ipOffset = ArchEntrypoints.registersIPField.getOffset();
    return Magic.objectAsAddress(this).plus(ipOffset);
  }
  public final void dump() {
    for (int i=0;i<NUM_GPRS;++i) {
      VM.sysWriteln("gprs[",i,"] = ",gprs.get(i));
    }
    for (int i=0;i<NUM_FPRS;++i) {
      VM.sysWriteln("fprs[",i,"] = ",fprs[i]);
    }
    VM.sysWriteln("ip = ",ip);
    VM.sysWriteln("fp = ",fp);
  }
}