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.compilers.baseline;
014
015import org.jikesrvm.VM;
016import org.jikesrvm.architecture.ArchConstants;
017import org.jikesrvm.classloader.ExceptionHandlerMap;
018import org.jikesrvm.classloader.TypeReference;
019import 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 */
025final 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]] << ArchConstants.getLogInstructionWidth();
044      eTable[i * 4 + TRY_END] =
045          bytecodeMap[endPCs[i]] << ArchConstants.getLogInstructionWidth();
046      eTable[i * 4 + CATCH_START] =
047          bytecodeMap[handlerPCs[i]] << ArchConstants.getLogInstructionWidth();
048      try {
049        eTable[i * 4 + EX_TYPE] = exceptionTypes[i].resolve().getId();
050      } catch (NoClassDefFoundError except) {
051        // For now, we are forcing early loading of exception types to
052        // avoid a bunch of ugly issues in resolving the type when delivering
053        // the exception.  The problem is that we currently can't allow a GC
054        // while in the midst of delivering an exception and resolving the
055        // type reference might entail calling arbitrary classloader code.
056        VM.sysWriteln("Trouble resolving a caught exception at compile time:");
057        except.printStackTrace(); // sysFail won't print the stack trace that
058        // lead to the NoClassDefFoundError.
059        VM.sysFail("Unable to resolve caught exception type at compile time");
060      }
061    }
062    return eTable;
063  }
064}