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.baseline;
014    
015    import org.jikesrvm.ArchitectureSpecific;
016    import org.jikesrvm.VM;
017    import org.jikesrvm.classloader.ExceptionHandlerMap;
018    import org.jikesrvm.classloader.TypeReference;
019    import org.jikesrvm.compilers.common.ExceptionTable;
020    
021    /**
022     * Encoding of try ranges in the final machinecode and the
023     * corresponding exception type and catch block start.
024     */
025    final class BaselineExceptionTable extends ExceptionTable {
026    
027      /**
028       * Encode an exception table
029       * @param emap the exception table to encode
030       * @param bytecodeMap mapping from bytecode to machinecode offsets
031       * @return the encoded exception table
032       */
033      static int[] encode(ExceptionHandlerMap emap, int[] bytecodeMap) {
034        int[] startPCs = emap.getStartPC();
035        int[] endPCs = emap.getEndPC();
036        int[] handlerPCs = emap.getHandlerPC();
037        TypeReference[] exceptionTypes = emap.getExceptionTypes();
038        int tableSize = startPCs.length;
039        int[] eTable = new int[tableSize * 4];
040    
041        for (int i = 0; i < tableSize; i++) {
042          eTable[i * 4 + TRY_START] =
043              bytecodeMap[startPCs[i]] << ArchitectureSpecific.RegisterConstants.LG_INSTRUCTION_WIDTH;
044          eTable[i * 4 + TRY_END] =
045              bytecodeMap[endPCs[i]] << ArchitectureSpecific.RegisterConstants.LG_INSTRUCTION_WIDTH;
046          eTable[i * 4 + CATCH_START] =
047              bytecodeMap[handlerPCs[i]] << ArchitectureSpecific.RegisterConstants.LG_INSTRUCTION_WIDTH;
048          try {
049            eTable[i * 4 + EX_TYPE] = exceptionTypes[i].resolve().getId();
050          } catch (NoClassDefFoundError except) {
051            // Yuck.  If this happens beatup Dave and make him do the right thing.
052            // For now, we are forcing early loading of exception types to
053            // avoid a bunch of ugly issues in resolving the type when delivering
054            // the exception.  The problem is that we currently can't allow a GC
055            // while in the midst of delivering an exception and resolving the
056            // type reference might entail calling arbitrary classloader code.
057            VM.sysWriteln("Trouble resolving a caught exception at compile time:");
058            except.printStackTrace(); // sysFail won't print the stack trace that
059            // lead to the NoClassDefFoundError.
060            VM.sysFail("Unable to resolve caught exception type at compile time");
061          }
062        }
063        return eTable;
064      }
065    }