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     */
013    package org.jikesrvm.compilers.common;
014    
015    import org.jikesrvm.ArchitectureSpecific;
016    import org.jikesrvm.SizeConstants;
017    import org.jikesrvm.mm.mminterface.GCMapIterator;
018    import org.jikesrvm.runtime.Magic;
019    import org.vmmagic.pragma.Uninterruptible;
020    import org.vmmagic.unboxed.Address;
021    import org.vmmagic.unboxed.Offset;
022    import org.vmmagic.unboxed.WordArray;
023    
024    /**
025     * Iterator for stack frames inserted by hardware trap handler.
026     * Such frames are purely used as markers.
027     * They contain no object references or JSR return addresses.
028     */
029    @Uninterruptible
030    public final class HardwareTrapGCMapIterator extends GCMapIterator implements SizeConstants {
031    
032      public HardwareTrapGCMapIterator(WordArray registerLocations) {
033        this.registerLocations = registerLocations;
034      }
035    
036      public void setupIterator(CompiledMethod compiledMethod, Offset instructionOffset, Address framePtr) {
037        this.framePtr = framePtr;
038      }
039    
040      public Address getNextReferenceAddress() {
041        // update register locations, noting that the trap handler represented by this stackframe
042        // saved all registers into the thread's "exceptionRegisters" object
043        //
044        Address registerLocation = Magic.objectAsAddress(thread.getExceptionRegisters().gprs);
045        for (int i = 0; i < ArchitectureSpecific.ArchConstants.NUM_GPRS; ++i) {
046          registerLocations.set(i, registerLocation.toWord());
047          registerLocation = registerLocation.plus(BYTES_IN_ADDRESS);
048        }
049        return Address.zero();
050      }
051    
052      public Address getNextReturnAddressAddress() {
053        return Address.zero();
054      }
055    
056      public void reset() {}
057    
058      public void cleanupPointers() {}
059    
060      public int getType() {
061        return CompiledMethod.TRAP;
062      }
063    }