    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 *  Unless required by applicable law or agreed to in writing, software
    012 *  distributed under the License is distributed on an "AS IS" BASIS,
    013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 *  See the License for the specific language governing permissions and
    015 *  limitations under the License.
    016 */
    017package org.apache.bcel.util;
    018
    019import java.util.ArrayList;
    020import java.util.Arrays;
    021import java.util.HashMap;
    022import java.util.Iterator;
    023import java.util.List;
    024import java.util.Locale;
    025import java.util.Map;
    026import java.util.regex.Matcher;
    027import java.util.regex.Pattern;
    028
    029import org.apache.bcel.Const;
    030import org.apache.bcel.generic.ClassGenException;
    031import org.apache.bcel.generic.InstructionHandle;
    032import org.apache.bcel.generic.InstructionList;
    033
    034/**
    035 * InstructionFinder is a tool to search for given instructions patterns, i.e., match sequences of instructions in an
    036 * instruction list via regular expressions. This can be used, e.g., in order to implement a peep hole optimizer that
    037 * looks for code patterns and replaces them with faster equivalents.
    038 *
    039 * <p>
    040 * This class internally uses the java.util.regex package to search for regular expressions.
    041 *
    042 * A typical application would look like this:
    043 *
    044 * <pre>
    045 *
    046 *
    047 *   InstructionFinder f   = new InstructionFinder(il);
    048 *   String            pat = &quot;IfInstruction ICONST_0 GOTO ICONST_1 NOP (IFEQ|IFNE)&quot;;
    049 *
    050 *   for (Iterator i = f.search(pat, constraint); i.hasNext(); ) {
    051 *   InstructionHandle[] match = (InstructionHandle[])i.next();
    052 *   ...
    053 *   il.delete(match[1], match[5]);
    054 *   ...
    055 *   }
    056 *
    057 *
    058 * </pre>
    059 *
    060 * @see org.apache.bcel.generic.Instruction
    061 * @see InstructionList
    062 */
    063public class InstructionFinder {
    064
    065    /**
    066     * Code patterns found may be checked using an additional user-defined constraint object whether they really match the
    067     * needed criterion. I.e., check constraints that can not expressed with regular expressions.
    068     */
    069    public interface CodeConstraint {
    070
    071        /**
    072         * @param match array of instructions matching the requested pattern
    073         * @return true if the matched area is really useful
    074         */
    075        boolean checkCode(InstructionHandle[] match);
    076    }
    077
    078    private static final int OFFSET = 32767; // char + OFFSET is outside of LATIN-1
    079    private static final int NO_OPCODES = 256; // Potential number, some are not used
    080    private static final Map<String, String> map = new HashMap<>();
    081
    082    // Initialize pattern map
    083    static {
    084        map.put("arithmeticinstruction",
    085            "(irem|lrem|iand|ior|ineg|isub|lneg|fneg|fmul|ldiv|fadd|lxor|frem|idiv|land|ixor|ishr|fsub|lshl|fdiv|iadd|lor|dmul|lsub|ishl|imul|lmul|lushr|dneg|iushr|lshr|ddiv|drem|dadd|ladd|dsub)");
    086        map.put("invokeinstruction", "(invokevirtual|invokeinterface|invokestatic|invokespecial|invokedynamic)");
    087        map.put("arrayinstruction",
    088            "(baload|aastore|saload|caload|fastore|lastore|iaload|castore|iastore|aaload|bastore|sastore|faload|laload|daload|dastore)");
    089        map.put("gotoinstruction", "(goto|goto_w)");
    090        map.put("conversioninstruction", "(d2l|l2d|i2s|d2i|l2i|i2b|l2f|d2f|f2i|i2d|i2l|f2d|i2c|f2l|i2f)");
    091        map.put("localvariableinstruction", "(fstore|iinc|lload|dstore|dload|iload|aload|astore|istore|fload|lstore)");
    092        map.put("loadinstruction", "(fload|dload|lload|iload|aload)");
    093        map.put("fieldinstruction", "(getfield|putstatic|getstatic|putfield)");
    094        map.put("cpinstruction",
    095            "(ldc2_w|invokeinterface|invokedynamic|multianewarray|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|ldc_w|invokestatic|invokevirtual|putfield|ldc|new|anewarray)");
    096        map.put("stackinstruction", "(dup2|swap|dup2_x2|pop|pop2|dup|dup2_x1|dup_x2|dup_x1)");
    097        map.put("branchinstruction",
    098            "(ifle|if_acmpne|if_icmpeq|if_acmpeq|ifnonnull|goto_w|iflt|ifnull|if_icmpne|tableswitch|if_icmple|ifeq|if_icmplt|jsr_w|if_icmpgt|ifgt|jsr|goto|ifne|ifge|lookupswitch|if_icmpge)");
    099        map.put("returninstruction", "(lreturn|ireturn|freturn|dreturn|areturn|return)");
    100        map.put("storeinstruction", "(istore|fstore|dstore|astore|lstore)");
    101        map.put("select", "(tableswitch|lookupswitch)");
    102        map.put("ifinstruction",
    103            "(ifeq|ifgt|if_icmpne|if_icmpeq|ifge|ifnull|ifne|if_icmple|if_icmpge|if_acmpeq|if_icmplt|if_acmpne|ifnonnull|iflt|if_icmpgt|ifle)");
    104        map.put("jsrinstruction", "(jsr|jsr_w)");
    105        map.put("variablelengthinstruction", "(tableswitch|jsr|goto|lookupswitch)");
    106        map.put("unconditionalbranch", "(goto|jsr|jsr_w|athrow|goto_w)");
    107        map.put("constantpushinstruction", "(dconst|bipush|sipush|fconst|iconst|lconst)");
    108        map.put("typedinstruction",
    109            "(imul|lsub|aload|fload|lor|new|aaload|fcmpg|iand|iaload|lrem|idiv|d2l|isub|dcmpg|dastore|ret|f2d|f2i|drem|iinc|i2c|checkcast|frem|lreturn|astore|lushr|daload|dneg|fastore|istore|lshl|ldiv|lstore|areturn|ishr|ldc_w|invokeinterface|invokedynamic|aastore|lxor|ishl|l2d|i2f|return|faload|sipush|iushr|caload|instanceof|invokespecial|putfield|fmul|ireturn|laload|d2f|lneg|ixor|i2l|fdiv|lastore|multianewarray|i2b|getstatic|i2d|putstatic|fcmpl|saload|ladd|irem|dload|jsr_w|dconst|dcmpl|fsub|freturn|ldc|aconst_null|castore|lmul|ldc2_w|dadd|iconst|f2l|ddiv|dstore|land|jsr|anewarray|dmul|bipush|dsub|sastore|d2i|i2s|lshr|iadd|l2i|lload|bastore|fstore|fneg|iload|fadd|baload|fconst|ior|ineg|dreturn|l2f|lconst|getfield|invokevirtual|invokestatic|iastore)");
    110        map.put("popinstruction", "(fstore|dstore|pop|pop2|astore|putstatic|istore|lstore)");
    111        map.put("allocationinstruction", "(multianewarray|new|anewarray|newarray)");
    112        map.put("indexedinstruction",
    113            "(lload|lstore|fload|ldc2_w|invokeinterface|invokedynamic|multianewarray|astore|dload|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|dstore|istore|iinc|ldc_w|ret|fstore|invokestatic|iload|putfield|invokevirtual|ldc|new|aload|anewarray)");
    114        map.put("pushinstruction", "(dup|lload|dup2|bipush|fload|ldc2_w|sipush|lconst|fconst|dload|getstatic|ldc_w|aconst_null|dconst|iload|ldc|iconst|aload)");
    115        map.put("stackproducer",
    116            "(imul|lsub|aload|fload|lor|new|aaload|fcmpg|iand|iaload|lrem|idiv|d2l|isub|dcmpg|dup|f2d|f2i|drem|i2c|checkcast|frem|lushr|daload|dneg|lshl|ldiv|ishr|ldc_w|invokeinterface|invokedynamic|lxor|ishl|l2d|i2f|faload|sipush|iushr|caload|instanceof|invokespecial|fmul|laload|d2f|lneg|ixor|i2l|fdiv|getstatic|i2b|swap|i2d|dup2|fcmpl|saload|ladd|irem|dload|jsr_w|dconst|dcmpl|fsub|ldc|arraylength|aconst_null|tableswitch|lmul|ldc2_w|iconst|dadd|f2l|ddiv|land|jsr|anewarray|dmul|bipush|dsub|d2i|newarray|i2s|lshr|iadd|lload|l2i|fneg|iload|fadd|baload|fconst|lookupswitch|ior|ineg|lconst|l2f|getfield|invokevirtual|invokestatic)");
    117        map.put("stackconsumer",
    118            "(imul|lsub|lor|iflt|fcmpg|if_icmpgt|iand|ifeq|if_icmplt|lrem|ifnonnull|idiv|d2l|isub|dcmpg|dastore|if_icmpeq|f2d|f2i|drem|i2c|checkcast|frem|lreturn|astore|lushr|pop2|monitorexit|dneg|fastore|istore|lshl|ldiv|lstore|areturn|if_icmpge|ishr|monitorenter|invokeinterface|invokedynamic|aastore|lxor|ishl|l2d|i2f|return|iushr|instanceof|invokespecial|fmul|ireturn|d2f|lneg|ixor|pop|i2l|ifnull|fdiv|lastore|i2b|if_acmpeq|ifge|swap|i2d|putstatic|fcmpl|ladd|irem|dcmpl|fsub|freturn|ifgt|castore|lmul|dadd|f2l|ddiv|dstore|land|if_icmpne|if_acmpne|dmul|dsub|sastore|ifle|d2i|i2s|lshr|iadd|l2i|bastore|fstore|fneg|fadd|ior|ineg|ifne|dreturn|l2f|if_icmple|getfield|invokevirtual|invokestatic|iastore)");
    119        map.put("exceptionthrower",
    120            "(irem|lrem|laload|putstatic|baload|dastore|areturn|getstatic|ldiv|anewarray|iastore|castore|idiv|saload|lastore|fastore|putfield|lreturn|caload|getfield|return|aastore|freturn|newarray|instanceof|multianewarray|athrow|faload|iaload|aaload|dreturn|monitorenter|checkcast|bastore|arraylength|new|invokevirtual|sastore|ldc_w|ireturn|invokespecial|monitorexit|invokeinterface|invokedynamic|ldc|invokestatic|daload)");
    121        map.put("loadclass",
    122            "(multianewarray|invokeinterface|invokedynamic|instanceof|invokespecial|putfield|checkcast|putstatic|invokevirtual|new|getstatic|invokestatic|getfield|anewarray)");
    123        map.put("instructiontargeter",
    124            "(ifle|if_acmpne|if_icmpeq|if_acmpeq|ifnonnull|goto_w|iflt|ifnull|if_icmpne|tableswitch|if_icmple|ifeq|if_icmplt|jsr_w|if_icmpgt|ifgt|jsr|goto|ifne|ifge|lookupswitch|if_icmpge)");
    125        // Some aliases
    126        map.put("if_icmp", "(if_icmpne|if_icmpeq|if_icmple|if_icmpge|if_icmplt|if_icmpgt)");
    127        map.put("if_acmp", "(if_acmpeq|if_acmpne)");
    128        map.put("if", "(ifeq|ifne|iflt|ifge|ifgt|ifle)");
    129        // Precompile some aliases first
    130        map.put("iconst", precompile(Const.ICONST_0, Const.ICONST_5, Const.ICONST_M1));
    131        map.put("lconst", new String(new char[] {'(', makeChar(Const.LCONST_0), '|', makeChar(Const.LCONST_1), ')'}));
    132        map.put("dconst", new String(new char[] {'(', makeChar(Const.DCONST_0), '|', makeChar(Const.DCONST_1), ')'}));
    133        map.put("fconst", new String(new char[] {'(', makeChar(Const.FCONST_0), '|', makeChar(Const.FCONST_1), '|', makeChar(Const.FCONST_2), ')'}));
    134        map.put("lload", precompile(Const.LLOAD_0, Const.LLOAD_3, Const.LLOAD));
    135        map.put("iload", precompile(Const.ILOAD_0, Const.ILOAD_3, Const.ILOAD));
    136        map.put("dload", precompile(Const.DLOAD_0, Const.DLOAD_3, Const.DLOAD));
    137        map.put("fload", precompile(Const.FLOAD_0, Const.FLOAD_3, Const.FLOAD));
    138        map.put("aload", precompile(Const.ALOAD_0, Const.ALOAD_3, Const.ALOAD));
    139        map.put("lstore", precompile(Const.LSTORE_0, Const.LSTORE_3, Const.LSTORE));
    140        map.put("istore", precompile(Const.ISTORE_0, Const.ISTORE_3, Const.ISTORE));
    141        map.put("dstore", precompile(Const.DSTORE_0, Const.DSTORE_3, Const.DSTORE));
    142        map.put("fstore", precompile(Const.FSTORE_0, Const.FSTORE_3, Const.FSTORE));
    143        map.put("astore", precompile(Const.ASTORE_0, Const.ASTORE_3, Const.ASTORE));
    144        // Compile strings
    145        map.forEach((key, value) -> {
    146            final char ch = value.charAt(1); // Omit already precompiled patterns
    147            if (ch < OFFSET) {
    148                map.put(key, compilePattern(value)); // precompile all patterns
    149            }
    150        });
    151        // Add instruction alias to match anything
    152        final StringBuilder buf = new StringBuilder("(");
    153        for (short i = 0; i < NO_OPCODES; i++) {
    154            if (Const.getNoOfOperands(i) != Const.UNDEFINED) { // Not an invalid opcode
    155                buf.append(makeChar(i));
    156                if (i < NO_OPCODES - 1) {
    157                    buf.append('|');
    158                }
    159            }
    160        }
    161        buf.append(')');
    162        map.put("instruction", buf.toString());
    163    }
    164
    165    /**
    166     * Replace symbolic names of instructions with the appropriate character and remove all white space from string. Meta
    167     * characters such as +, * are ignored.
    168     *
    169     * @param pattern The pattern to compile
    170     * @return translated regular expression string
    171     */
    172    private static String compilePattern(final String pattern) {
    173        // Bug: BCEL-77 - Instructions are assumed to be english, to avoid odd Locale issues
    174        final String lower = pattern.toLowerCase(Locale.ENGLISH);
    175        final StringBuilder buf = new StringBuilder();
    176        final int size = pattern.length();
    177        for (int i = 0; i < size; i++) {
    178            char ch = lower.charAt(i);
    179            if (Character.isLetterOrDigit(ch)) {
    180                final StringBuilder name = new StringBuilder();
    181                while ((Character.isLetterOrDigit(ch) || ch == '_') && i < size) {
    182                    name.append(ch);
    183                    if (++i >= size) {
    184                        break;
    185                    }
    186                    ch = lower.charAt(i);
    187                }
    188                i--;
    189                buf.append(mapName(name.toString()));
    190            } else if (!Character.isWhitespace(ch)) {
    191                buf.append(ch);
    192            }
    193        }
    194        return buf.toString();
    195    }
    196
    197    /**
    198     * Convert opcode number to char.
    199     */
    200    private static char makeChar(final short opcode) {
    201        return (char) (opcode + OFFSET);
    202    }
    203
    204    /**
    205     * Map symbolic instruction names like "getfield" to a single character.
    206     *
    207     * @param pattern instruction pattern in lower case
    208     * @return encoded string for a pattern such as "BranchInstruction".
    209     */
    210    private static String mapName(final String pattern) {
    211        final String result = map.get(pattern);
    212        if (result != null) {
    213            return result;
    214        }
    215        for (short i = 0; i < NO_OPCODES; i++) {
    216            if (pattern.equals(Const.getOpcodeName(i))) {
    217                return String.valueOf(makeChar(i));
    218            }
    219        }
    220        throw new IllegalArgumentException("Instruction unknown: " + pattern);
    221    }
    222
    223    private static String precompile(final short from, final short to, final short extra) {
    224        final StringBuilder buf = new StringBuilder("(");
    225        for (short i = from; i <= to; i++) {
    226            buf.append(makeChar(i));
    227            buf.append('|');
    228        }
    229        buf.append(makeChar(extra));
    230        buf.append(")");
    231        return buf.toString();
    232    }
    233
    234    private final InstructionList il;
    235
    236    private String ilString; // instruction list as string
    237
    238    private InstructionHandle[] handles; // map instruction
    239
    240    // list to array
    241    /**
    242     * @param il instruction list to search for given patterns
    243     */
    244    public InstructionFinder(final InstructionList il) {
    245        this.il = il;
    246        reread();
    247    }
    248
    249    /**
    250     * @return the inquired instruction list
    251     */
    252    public final InstructionList getInstructionList() {
    253        return il;
    254    }
    255
    256    /**
    257     * @return the matched piece of code as an array of instruction (handles)
    258     */
    259    private InstructionHandle[] getMatch(final int matchedFrom, final int matchLength) {
    260        return Arrays.copyOfRange(handles, matchedFrom, matchedFrom + matchLength);
    261    }
    262
    263    /**
    264     * Reread the instruction list, e.g., after you've altered the list upon a match.
    265     */
    266    public final void reread() {
    267        final int size = il.getLength();
    268        final char[] buf = new char[size]; // Create a string with length equal to il length
    269        handles = il.getInstructionHandles();
    270        // Map opcodes to characters
    271        for (int i = 0; i < size; i++) {
    272            buf[i] = makeChar(handles[i].getInstruction().getOpcode());
    273        }
    274        ilString = new String(buf);
    275    }
    276
    277    /**
    278     * Start search beginning from the start of the given instruction list.
    279     *
    280     * @param pattern the instruction pattern to search for, where case is ignored
    281     * @return iterator of matches where e.nextElement() returns an array of instruction handles describing the matched area
    282     */
    283    public final Iterator<InstructionHandle[]> search(final String pattern) {
    284        return search(pattern, il.getStart(), null);
    285    }
    286
    287    /**
    288     * Start search beginning from the start of the given instruction list. Check found matches with the constraint object.
    289     *
    290     * @param pattern the instruction pattern to search for, case is ignored
    291     * @param constraint constraints to be checked on matching code
    292     * @return instruction handle or 'null' if the match failed
    293     */
    294    public final Iterator<InstructionHandle[]> search(final String pattern, final CodeConstraint constraint) {
    295        return search(pattern, il.getStart(), constraint);
    296    }
    297
    298    /**
    299     * Start search beginning from 'from'.
    300     *
    301     * @param pattern the instruction pattern to search for, where case is ignored
    302     * @param from where to start the search in the instruction list
    303     * @return iterator of matches where e.nextElement() returns an array of instruction handles describing the matched area
    304     */
    305    public final Iterator<InstructionHandle[]> search(final String pattern, final InstructionHandle from) {
    306        return search(pattern, from, null);
    307    }
    308
    309    /**
    310     * Search for the given pattern in the instruction list. You can search for any valid opcode via its symbolic name, e.g.
    311     * "istore". You can also use a super class or an interface name to match a whole set of instructions, e.g.
    312     * "BranchInstruction" or "LoadInstruction". "istore" is also an alias for all "istore_x" instructions. Additional
    313     * aliases are "if" for "ifxx", "if_icmp" for "if_icmpxx", "if_acmp" for "if_acmpxx".
    314     *
    315     * Consecutive instruction names must be separated by white space which will be removed during the compilation of the
    316     * pattern.
    317     *
    318     * For the rest the usual pattern matching rules for regular expressions apply.
    319     * <P>
    320     * Example pattern:
    321     *
    322     * <pre>
    323     * search(&quot;BranchInstruction NOP ((IfInstruction|GOTO)+ ISTORE Instruction)*&quot;);
    324     * </pre>
    325     *
    326     * <p>
    327     * If you alter the instruction list upon a match such that other matching areas are affected, you should call reread()
    328     * to update the finder and call search() again, because the matches are cached.
    329     *
    330     * @param pattern the instruction pattern to search for, where case is ignored
    331     * @param from where to start the search in the instruction list
    332     * @param constraint optional CodeConstraint to check the found code pattern for user-defined constraints
    333     * @return iterator of matches where e.nextElement() returns an array of instruction handles describing the matched area
    334     */
    335    public final Iterator<InstructionHandle[]> search(final String pattern, final InstructionHandle from, final CodeConstraint constraint) {
    336        final String search = compilePattern(pattern);
    337        int start = -1;
    338        for (int i = 0; i < handles.length; i++) {
    339            if (handles[i] == from) {
    340                start = i; // Where to start search from (index)
    341                break;
    342            }
    343        }
    344        if (start == -1) {
    345            throw new ClassGenException("Instruction handle " + from + " not found in instruction list.");
    346        }
    347        final Pattern regex = Pattern.compile(search);
    348        final List<InstructionHandle[]> matches = new ArrayList<>();
    349        final Matcher matcher = regex.matcher(ilString);
    350        while (start < ilString.length() && matcher.find(start)) {
    351            final int startExpr = matcher.start();
    352            final int endExpr = matcher.end();
    353            final int lenExpr = endExpr - startExpr;
    354            final InstructionHandle[] match = getMatch(startExpr, lenExpr);
    355            if (constraint == null || constraint.checkCode(match)) {
    356                matches.add(match);
    357            }
    358            start = endExpr;
    359        }
    360        return matches.iterator();
    361    }
    362
    363    /*
    364     * Internal debugging routines.
    365     */
    366//    private static final String pattern2string( String pattern ) {
    367//        return pattern2string(pattern, true);
    368//    }
    369
    370//    private static final String pattern2string( String pattern, boolean make_string ) {
    371//        StringBuilder buf = new StringBuilder();
    372//        for (int i = 0; i < pattern.length(); i++) {
    373//            char ch = pattern.charAt(i);
    374//            if (ch >= OFFSET) {
    375//                if (make_string) {
    376//                    buf.append(Constants.getOpcodeName(ch - OFFSET));
    377//                } else {
    378//                    buf.append((ch - OFFSET));
    379//                }
    380//            } else {
    381//                buf.append(ch);
    382//            }
    383//        }
    384//        return buf.toString();
    385//    }
    386}