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 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package jdk.nashorn.internal.ir.debug;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import jdk.internal.org.objectweb.asm.Attribute;
import jdk.internal.org.objectweb.asm.ClassReader;
import jdk.internal.org.objectweb.asm.ClassVisitor;
import jdk.internal.org.objectweb.asm.Label;
import jdk.nashorn.internal.ir.debug.NashornTextifier.NashornLabel;

Subclass of the ASM class reader that retains more info, such as bytecode offsets
/** * Subclass of the ASM class reader that retains more info, such * as bytecode offsets */
public class NashornClassReader extends ClassReader { private final Map<String, List<Label>> labelMap = new HashMap<>();
Constructor
Params:
  • bytecode – bytecode for class
/** * Constructor * @param bytecode bytecode for class */
public NashornClassReader(final byte[] bytecode) { super(bytecode); parse(bytecode); } List<Label> getExtraLabels(final String className, final String methodName, final String methodDesc) { final String key = fullyQualifiedName(className, methodName, methodDesc); return labelMap.get(key); } private static int readByte(final byte[] bytecode, final int index) { return (byte)(bytecode[index] & 0xff); } private static int readShort(final byte[] bytecode, final int index) { return (short)((bytecode[index] & 0xff) << 8) | (bytecode[index + 1] & 0xff); } private static int readInt(final byte[] bytecode, final int index) { return ((bytecode[index] & 0xff) << 24) | ((bytecode[index + 1] & 0xff) << 16) | ((bytecode[index + 2] & 0xff) << 8) | (bytecode[index + 3] & 0xff); } private static long readLong(final byte[] bytecode, final int index) { final int hi = readInt(bytecode, index); final int lo = readInt(bytecode, index + 4); return ((long)hi << 32) | lo; } private static String readUTF(final int index, final int utfLen, final byte[] bytecode) { final int endIndex = index + utfLen; final char buf[] = new char[utfLen * 2]; int strLen = 0; int c; int st = 0; char cc = 0; int i = index; while (i < endIndex) { c = bytecode[i++]; switch (st) { case 0: c &= 0xFF; if (c < 0x80) { // 0xxxxxxx buf[strLen++] = (char) c; } else if (c < 0xE0 && c > 0xBF) { // 110x xxxx 10xx xxxx cc = (char) (c & 0x1F); st = 1; } else { // 1110 xxxx 10xx xxxx 10xx xxxx cc = (char) (c & 0x0F); st = 2; } break; case 1: // byte 2 of 2-byte char or byte 3 of 3-byte char buf[strLen++] = (char) ((cc << 6) | (c & 0x3F)); st = 0; break; case 2: // byte 2 of 3-byte char cc = (char) ((cc << 6) | (c & 0x3F)); st = 1; break; default: break; } } return new String(buf, 0, strLen); } private String parse(final byte[] bytecode) { String thisClassName; int u = 0; final int magic = readInt(bytecode, u); u += 4; //magic assert magic == 0xcafebabe : Integer.toHexString(magic); readShort(bytecode, u); //minor u += 2; readShort(bytecode, u); //major u += 2; //minor final int cpc = readShort(bytecode, u); u += 2; final ArrayList<Constant> cp = new ArrayList<>(cpc); cp.add(null); for (int i = 1; i < cpc; i++) { //constant pool entries final int tag = readByte(bytecode, u); u += 1; switch (tag) { case 7: //class cp.add(new IndexInfo(cp, tag, readShort(bytecode, u))); u += 2; break; case 9: //fieldref case 10: //methodref case 11: //interfacemethodref cp.add(new IndexInfo2(cp, tag, readShort(bytecode, u), readShort(bytecode, u + 2))); u += 4; break; case 8: //string cp.add(new IndexInfo(cp, tag, readShort(bytecode, u))); //string index u += 2; break; case 3: //int cp.add(new DirectInfo<>(cp, tag, readInt(bytecode, u))); u += 4; break; case 4: //float cp.add(new DirectInfo<>(cp, tag, Float.intBitsToFloat(readInt(bytecode, u)))); u += 4; break; case 5: //long cp.add(new DirectInfo<>(cp, tag, readLong(bytecode, u))); cp.add(null); i++; u += 8; break; case 6: //double cp.add(new DirectInfo<>(cp, tag, Double.longBitsToDouble(readLong(bytecode, u)))); cp.add(null); i++; u += 8; break; case 12: //name and type cp.add(new IndexInfo2(cp, tag, readShort(bytecode, u), readShort(bytecode, u + 2))); u += 4; break; case 1: //utf8 final int len = readShort(bytecode, u); u += 2; cp.add(new DirectInfo<>(cp, tag, readUTF(u, len, bytecode))); u += len; break; case 16: //methodtype cp.add(new IndexInfo(cp, tag, readShort(bytecode, u))); u += 2; break; case 18: //indy cp.add(new IndexInfo2(cp, tag, readShort(bytecode, u), readShort(bytecode, u + 2)) { @Override public String toString() { return "#" + index + ' ' + cp.get(index2).toString(); } }); u += 4; break; case 15: //methodhandle final int kind = readByte(bytecode, u); assert kind >= 1 && kind <= 9 : kind; cp.add(new IndexInfo2(cp, tag, kind, readShort(bytecode, u + 1)) { @Override public String toString() { return "#" + index + ' ' + cp.get(index2).toString(); } }); u += 3; break; default: assert false : tag; break; } } readShort(bytecode, u); //access flags u += 2; //access final int cls = readShort(bytecode, u); u += 2; //this_class thisClassName = cp.get(cls).toString(); u += 2; //super final int ifc = readShort(bytecode, u); u += 2; u += ifc * 2; final int fc = readShort(bytecode, u); u += 2; //fields for (int i = 0 ; i < fc ; i++) { u += 2; //access readShort(bytecode, u); //fieldname u += 2; //name u += 2; //descriptor final int ac = readShort(bytecode, u); u += 2; //field attributes for (int j = 0; j < ac; j++) { u += 2; //attribute name final int len = readInt(bytecode, u); u += 4; u += len; } } final int mc = readShort(bytecode, u); u += 2; for (int i = 0 ; i < mc ; i++) { readShort(bytecode, u); u += 2; //access final int methodNameIndex = readShort(bytecode, u); u += 2; final String methodName = cp.get(methodNameIndex).toString(); final int methodDescIndex = readShort(bytecode, u); u += 2; final String methodDesc = cp.get(methodDescIndex).toString(); final int ac = readShort(bytecode, u); u += 2; //method attributes for (int j = 0; j < ac; j++) { final int nameIndex = readShort(bytecode, u); u += 2; final String attrName = cp.get(nameIndex).toString(); final int attrLen = readInt(bytecode, u); u += 4; if ("Code".equals(attrName)) { readShort(bytecode, u); u += 2; //max stack readShort(bytecode, u); u += 2; //max locals final int len = readInt(bytecode, u); u += 4; parseCode(bytecode, u, len, fullyQualifiedName(thisClassName, methodName, methodDesc)); u += len; final int elen = readShort(bytecode, u); //exception table length u += 2; u += elen * 8; //method attributes final int ac2 = readShort(bytecode, u); u += 2; for (int k = 0; k < ac2; k++) { u += 2; //name; final int aclen = readInt(bytecode, u); u += 4; //length u += aclen; //bytes; } } else { u += attrLen; } } } final int ac = readShort(bytecode, u); u += 2; //other attributes for (int i = 0 ; i < ac ; i++) { readShort(bytecode, u); //name index u += 2; final int len = readInt(bytecode, u); u += 4; u += len; //attribute } return thisClassName; } private static String fullyQualifiedName(final String className, final String methodName, final String methodDesc) { return className + '.' + methodName + methodDesc; } private void parseCode(final byte[] bytecode, final int index, final int len, final String desc) { final List<Label> labels = new ArrayList<>(); labelMap.put(desc, labels); boolean wide = false; for (int i = index; i < index + len;) { final int opcode = bytecode[i]; labels.add(new NashornLabel(opcode, i - index)); switch (opcode & 0xff) { case 0xc4: //wide wide = true; i += 1; break; case 0xa9: //ret i += wide ? 4 : 2; break; case 0xab: //lookupswitch i += 1; while (((i - index) & 3) != 0) { i++; } readInt(bytecode, i); i += 4; //defaultbyte final int npairs = readInt(bytecode, i); i += 4; i += 8 * npairs; break; case 0xaa: //tableswitch i += 1; while (((i - index) & 3) != 0) { i++; } readInt(bytecode, i); //default i += 4; final int lo = readInt(bytecode, i); i += 4; final int hi = readInt(bytecode, i); i += 4; i += 4 * (hi - lo + 1); break; case 0xc5: //multianewarray i += 4; break; case 0x19: //aload (wide) case 0x18: //dload case 0x17: //fload case 0x15: //iload case 0x16: //lload case 0x3a: //astore wide case 0x39: //dstore case 0x38: //fstore case 0x36: //istore case 0x37: //lstore i += wide ? 3 : 2; break; case 0x10: //bipush case 0x12: //ldc case 0xbc: //anewarrayu i += 2; break; case 0xb4: //getfield case 0xb2: //getstatic case 0xbd: //anewarray case 0xc0: //checkcast case 0xa5: //ifacmp_eq case 0xa6: //ifacmp_ne case 0x9f: //all ifs and ifcmps case 0xa0: case 0xa1: case 0xa2: case 0xa3: case 0xa4: case 0x99: case 0x9a: case 0x9b: case 0x9c: case 0x9d: case 0x9e: case 0xc7: case 0xc6: case 0xc1: //instanceof case 0xa7: //goto case 0xb7: //special case 0xb8: //static case 0xb6: //virtual case 0xa8: //jsr case 0x13: //ldc_w case 0x14: //ldc2_w case 0xbb: //new case 0xb5: //putfield case 0xb3: //putstatic case 0x11: //sipush i += 3; break; case 0x84: //iinc (wide) i += wide ? 5 : 3; break; case 0xba: //indy case 0xb9: //interface case 0xc8: case 0xc9: //jsr_w i += 5; //goto_w break; default: i++; break; } if (wide) { wide = false; } } } @Override public void accept(final ClassVisitor classVisitor, final Attribute[] attrs, final int flags) { super.accept(classVisitor, attrs, flags); } @Override protected Label readLabel(final int offset, final Label[] labels) { final Label label = super.readLabel(offset, labels); label.info = offset; return label; } private abstract static class Constant { protected ArrayList<Constant> cp; protected int tag; protected Constant(final ArrayList<Constant> cp, final int tag) { this.cp = cp; this.tag = tag; } @SuppressWarnings("unused") final String getType() { String str = TYPE[tag]; while (str.length() < 16) { str += " "; } return str; } } private static class IndexInfo extends Constant { protected final int index; IndexInfo(final ArrayList<Constant> cp, final int tag, final int index) { super(cp, tag); this.index = index; } @Override public String toString() { return cp.get(index).toString(); } } private static class IndexInfo2 extends IndexInfo { protected final int index2; IndexInfo2(final ArrayList<Constant> cp, final int tag, final int index, final int index2) { super(cp, tag, index); this.index2 = index2; } @Override public String toString() { return super.toString() + ' ' + cp.get(index2).toString(); } } private static class DirectInfo<T> extends Constant { protected final T info; DirectInfo(final ArrayList<Constant> cp, final int tag, final T info) { super(cp, tag); this.info = info; } @Override public String toString() { return info.toString();// + " [class=" + info.getClass().getSimpleName() + ']'; } } private static final String[] TYPE = { //0 "<error>", //1 "UTF8", //2 "<error>", //3 "Integer", //4 "Float", //5 "Long", //6 "Double", //7 "Class", //8 "String", //9 "Fieldref", //10 "Methodref", //11 "InterfaceMethodRef", //12 "NameAndType", //13 "<error>", //14 "<error>", //15 "MethodHandle", //16 "MethodType", //17 "<error>", //18 "Invokedynamic" }; }