    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.bcel.util;
    020
    021import java.util.ArrayList;
    022import java.util.Arrays;
    023import java.util.HashMap;
    024import java.util.Iterator;
    025import java.util.List;
    026import java.util.Map;
    027import java.util.regex.Matcher;
    028import java.util.regex.Pattern;
    029
    030import org.apache.bcel.Const;
    031import org.apache.bcel.generic.ClassGenException;
    032import org.apache.bcel.generic.InstructionHandle;
    033import org.apache.bcel.generic.InstructionList;
    034import org.apache.commons.lang3.StringUtils;
    035
    036/**
    037 * InstructionFinder is a tool to search for given instructions patterns, i.e., match sequences of instructions in an
    038 * instruction list via regular expressions. This can be used, for example, in order to implement a peep hole optimizer that
    039 * looks for code patterns and replaces them with faster equivalents.
    040 *
    041 * <p>
    042 * This class internally uses the java.util.regex package to search for regular expressions.
    043 *
    044 * A typical application would look like this:
    045 *
    046 * <pre>
    047 *
    048 *
    049 *   InstructionFinder f   = new InstructionFinder(il);
    050 *   String            pat = &quot;IfInstruction ICONST_0 GOTO ICONST_1 NOP (IFEQ|IFNE)&quot;;
    051 *
    052 *   for (Iterator i = f.search(pat, constraint); i.hasNext(); ) {
    053 *   InstructionHandle[] match = (InstructionHandle[])i.next();
    054 *   ...
    055 *   il.delete(match[1], match[5]);
    056 *   ...
    057 *   }
    058 *
    059 *
    060 * </pre>
    061 *
    062 * @see org.apache.bcel.generic.Instruction
    063 * @see InstructionList
    064 */
    065public class InstructionFinder {
    066
    067    /**
    068     * Code patterns found may be checked using an additional user-defined constraint object whether they really match the
    069     * needed criterion. I.e., check constraints that cannot expressed with regular expressions.
    070     */
    071    public interface CodeConstraint {
    072
    073        /**
    074         * @param match array of instructions matching the requested pattern
    075         * @return true if the matched area is really useful
    076         */
    077        boolean checkCode(InstructionHandle[] match);
    078    }
    079
    080    private static final int OFFSET = 32767; // char + OFFSET is outside of LATIN-1
    081    private static final int NO_OPCODES = 256; // Potential number, some are not used
    082    private static final Map<String, String> map = new HashMap<>();
    083
    084    // Initialize pattern map
    085    static {
    086        map.put("arithmeticinstruction",
    087            "(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)");
    088        map.put("invokeinstruction", "(invokevirtual|invokeinterface|invokestatic|invokespecial|invokedynamic)");
    089        map.put("arrayinstruction",
    090            "(baload|aastore|saload|caload|fastore|lastore|iaload|castore|iastore|aaload|bastore|sastore|faload|laload|daload|dastore)");
    091        map.put("gotoinstruction", "(goto|goto_w)");
    092        map.put("conversioninstruction", "(d2l|l2d|i2s|d2i|l2i|i2b|l2f|d2f|f2i|i2d|i2l|f2d|i2c|f2l|i2f)");
    093        map.put("localvariableinstruction", "(fstore|iinc|lload|dstore|dload|iload|aload|astore|istore|fload|lstore)");
    094        map.put("loadinstruction", "(fload|dload|lload|iload|aload)");
    095        map.put("fieldinstruction", "(getfield|putstatic|getstatic|putfield)");
    096        map.put("cpinstruction",
    097            "(ldc2_w|invokeinterface|invokedynamic|multianewarray|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|ldc_w|invokestatic|invokevirtual|putfield|ldc|new|anewarray)");
    098        map.put("stackinstruction", "(dup2|swap|dup2_x2|pop|pop2|dup|dup2_x1|dup_x2|dup_x1)");
    099        map.put("branchinstruction",
    100            "(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)");
    101        map.put("returninstruction", "(lreturn|ireturn|freturn|dreturn|areturn|return)");
    102        map.put("storeinstruction", "(istore|fstore|dstore|astore|lstore)");
    103        map.put("select", "(tableswitch|lookupswitch)");
    104        map.put("ifinstruction",
    105            "(ifeq|ifgt|if_icmpne|if_icmpeq|ifge|ifnull|ifne|if_icmple|if_icmpge|if_acmpeq|if_icmplt|if_acmpne|ifnonnull|iflt|if_icmpgt|ifle)");
    106        map.put("jsrinstruction", "(jsr|jsr_w)");
    107        map.put("variablelengthinstruction", "(tableswitch|jsr|goto|lookupswitch)");
    108        map.put("unconditionalbranch", "(goto|jsr|jsr_w|athrow|goto_w)");
    109        map.put("constantpushinstruction", "(dconst|bipush|sipush|fconst|iconst|lconst)");
    110        map.put("typedinstruction",
    111            "(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)");
    112        map.put("popinstruction", "(fstore|dstore|pop|pop2|astore|putstatic|istore|lstore)");
    113        map.put("allocationinstruction", "(multianewarray|new|anewarray|newarray)");
    114        map.put("indexedinstruction",
    115            "(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)");
    116        map.put("pushinstruction", "(dup|lload|dup2|bipush|fload|ldc2_w|sipush|lconst|fconst|dload|getstatic|ldc_w|aconst_null|dconst|iload|ldc|iconst|aload)");
    117        map.put("stackproducer",
    118            "(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)");
    119        map.put("stackconsumer",
    120            "(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)");
    121        map.put("exceptionthrower",
    122            "(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)");
    123        map.put("loadclass",
    124            "(multianewarray|invokeinterface|invokedynamic|instanceof|invokespecial|putfield|checkcast|putstatic|invokevirtual|new|getstatic|invokestatic|getfield|anewarray)");
    125        map.put("instructiontargeter",
    126            "(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)");
    127        // Some aliases
    128        map.put("if_icmp", "(if_icmpne|if_icmpeq|if_icmple|if_icmpge|if_icmplt|if_icmpgt)");
    129        map.put("if_acmp", "(if_acmpeq|if_acmpne)");
    130        map.put("if", "(ifeq|ifne|iflt|ifge|ifgt|ifle)");
    131        // Precompile some aliases first
    132        map.put("iconst", precompile(Const.ICONST_0, Const.ICONST_5, Const.ICONST_M1));
    133        map.put("lconst", new String(new char[] {'(', makeChar(Const.LCONST_0), '|', makeChar(Const.LCONST_1), ')'}));
    134        map.put("dconst", new String(new char[] {'(', makeChar(Const.DCONST_0), '|', makeChar(Const.DCONST_1), ')'}));
    135        map.put("fconst", new String(new char[] {'(', makeChar(Const.FCONST_0), '|', makeChar(Const.FCONST_1), '|', makeChar(Const.FCONST_2), ')'}));
    136        map.put("lload", precompile(Const.LLOAD_0, Const.LLOAD_3, Const.LLOAD));
    137        map.put("iload", precompile(Const.ILOAD_0, Const.ILOAD_3, Const.ILOAD));
    138        map.put("dload", precompile(Const.DLOAD_0, Const.DLOAD_3, Const.DLOAD));
    139        map.put("fload", precompile(Const.FLOAD_0, Const.FLOAD_3, Const.FLOAD));
    140        map.put("aload", precompile(Const.ALOAD_0, Const.ALOAD_3, Const.ALOAD));
    141        map.put("lstore", precompile(Const.LSTORE_0, Const.LSTORE_3, Const.LSTORE));
    142        map.put("istore", precompile(Const.ISTORE_0, Const.ISTORE_3, Const.ISTORE));
    143        map.put("dstore", precompile(Const.DSTORE_0, Const.DSTORE_3, Const.DSTORE));
    144        map.put("fstore", precompile(Const.FSTORE_0, Const.FSTORE_3, Const.FSTORE));
    145        map.put("astore", precompile(Const.ASTORE_0, Const.ASTORE_3, Const.ASTORE));
    146        // Compile strings
    147        map.forEach((key, value) -> {
    148            final char ch = value.charAt(1); // Omit already precompiled patterns
    149            if (ch < OFFSET) {
    150                map.put(key, compilePattern(value)); // precompile all patterns
    151            }
    152        });
    153        // Add instruction alias to match anything
    154        final StringBuilder buf = new StringBuilder("(");
    155        for (short i = 0; i < NO_OPCODES; i++) {
    156            if (Const.getNoOfOperands(i) != Const.UNDEFINED) { // Not an invalid opcode
    157                buf.append(makeChar(i));
    158                if (i < NO_OPCODES - 1) {
    159                    buf.append('|');
    160                }
    161            }
    162        }
    163        buf.append(')');
    164        map.put("instruction", buf.toString());
    165    }
    166
    167    /**
    168     * Replace symbolic names of instructions with the appropriate character and remove all white space from string. Meta
    169     * characters such as +, * are ignored.
    170     *
    171     * @param pattern The pattern to compile
    172     * @return translated regular expression string
    173     */
    174    private static String compilePattern(final String pattern) {
    175        // Bug: BCEL-77 - Instructions are assumed to be english, to avoid odd Locale issues
    176        final String lower = StringUtils.toRootLowerCase(pattern);
    177        final StringBuilder buf = new StringBuilder();
    178        final int size = pattern.length();
    179        for (int i = 0; i < size; i++) {
    180            char ch = lower.charAt(i);
    181            if (Character.isLetterOrDigit(ch)) {
    182                final StringBuilder name = new StringBuilder();
    183                while ((Character.isLetterOrDigit(ch) || ch == '_') && i < size) {
    184                    name.append(ch);
    185                    if (++i >= size) {
    186                        break;
    187                    }
    188                    ch = lower.charAt(i);
    189                }
    190                i--;
    191                buf.append(mapName(name.toString()));
    192            } else if (!Character.isWhitespace(ch)) {
    193                buf.append(ch);
    194            }
    195        }
    196        return buf.toString();
    197    }
    198
    199    /**
    200     * Convert opcode number to char.
    201     */
    202    private static char makeChar(final short opcode) {
    203        return (char) (opcode + OFFSET);
    204    }
    205
    206    /**
    207     * Map symbolic instruction names like "getfield" to a single character.
    208     *
    209     * @param pattern instruction pattern in lower case
    210     * @return encoded string for a pattern such as "BranchInstruction".
    211     */
    212    private static String mapName(final String pattern) {
    213        final String result = map.get(pattern);
    214        if (result != null) {
    215            return result;
    216        }
    217        for (short i = 0; i < NO_OPCODES; i++) {
    218            if (pattern.equals(Const.getOpcodeName(i))) {
    219                return String.valueOf(makeChar(i));
    220            }
    221        }
    222        throw new IllegalArgumentException("Instruction unknown: " + pattern);
    223    }
    224
    225    private static String precompile(final short from, final short to, final short extra) {
    226        final StringBuilder buf = new StringBuilder("(");
    227        for (short i = from; i <= to; i++) {
    228            buf.append(makeChar(i));
    229            buf.append('|');
    230        }
    231        buf.append(makeChar(extra));
    232        buf.append(")");
    233        return buf.toString();
    234    }
    235
    236    private final InstructionList il;
    237
    238    private String ilString; // instruction list as string
    239
    240    private InstructionHandle[] handles; // map instruction
    241
    242    // list to array
    243    /**
    244     * @param il instruction list to search for given patterns
    245     */
    246    public InstructionFinder(final InstructionList il) {
    247        this.il = il;
    248        reread();
    249    }
    250
    251    /**
    252     * @return the inquired instruction list
    253     */
    254    public final InstructionList getInstructionList() {
    255        return il;
    256    }
    257
    258    /**
    259     * @return the matched piece of code as an array of instruction (handles)
    260     */
    261    private InstructionHandle[] getMatch(final int matchedFrom, final int matchLength) {
    262        return Arrays.copyOfRange(handles, matchedFrom, matchedFrom + matchLength);
    263    }
    264
    265    /**
    266     * Reread the instruction list, for example, after you've altered the list upon a match.
    267     */
    268    public final void reread() {
    269        final int size = il.getLength();
    270        final char[] buf = new char[size]; // Create a string with length equal to il length
    271        handles = il.getInstructionHandles();
    272        // Map opcodes to characters
    273        for (int i = 0; i < size; i++) {
    274            buf[i] = makeChar(handles[i].getInstruction().getOpcode());
    275        }
    276        ilString = new String(buf);
    277    }
    278
    279    /**
    280     * Start search beginning from the start of the given instruction list.
    281     *
    282     * @param pattern the instruction pattern to search for, where case is ignored
    283     * @return iterator of matches where e.nextElement() returns an array of instruction handles describing the matched area
    284     */
    285    public final Iterator<InstructionHandle[]> search(final String pattern) {
    286        return search(pattern, il.getStart(), null);
    287    }
    288
    289    /**
    290     * Start search beginning from the start of the given instruction list. Check found matches with the constraint object.
    291     *
    292     * @param pattern the instruction pattern to search for, case is ignored
    293     * @param constraint constraints to be checked on matching code
    294     * @return instruction handle or 'null' if the match failed
    295     */
    296    public final Iterator<InstructionHandle[]> search(final String pattern, final CodeConstraint constraint) {
    297        return search(pattern, il.getStart(), constraint);
    298    }
    299
    300    /**
    301     * Start search beginning from 'from'.
    302     *
    303     * @param pattern the instruction pattern to search for, where case is ignored
    304     * @param from where to start the search in the instruction list
    305     * @return iterator of matches where e.nextElement() returns an array of instruction handles describing the matched area
    306     */
    307    public final Iterator<InstructionHandle[]> search(final String pattern, final InstructionHandle from) {
    308        return search(pattern, from, null);
    309    }
    310
    311    /**
    312     * Search for the given pattern in the instruction list. You can search for any valid opcode via its symbolic name, for example
    313     * "istore". You can also use a super class or an interface name to match a whole set of instructions, for example
    314     * "BranchInstruction" or "LoadInstruction". "istore" is also an alias for all "istore_x" instructions. Additional
    315     * aliases are "if" for "ifxx", "if_icmp" for "if_icmpxx", "if_acmp" for "if_acmpxx".
    316     *
    317     * Consecutive instruction names must be separated by white space which will be removed during the compilation of the
    318     * pattern.
    319     *
    320     * For the rest the usual pattern matching rules for regular expressions apply.
    321     * <P>
    322     * Example pattern:
    323     *
    324     * <pre>
    325     * search(&quot;BranchInstruction NOP ((IfInstruction|GOTO)+ ISTORE Instruction)*&quot;);
    326     * </pre>
    327     *
    328     * <p>
    329     * If you alter the instruction list upon a match such that other matching areas are affected, you should call reread()
    330     * to update the finder and call search() again, because the matches are cached.
    331     *
    332     * @param pattern the instruction pattern to search for, where case is ignored
    333     * @param from where to start the search in the instruction list
    334     * @param constraint optional CodeConstraint to check the found code pattern for user-defined constraints
    335     * @return iterator of matches where e.nextElement() returns an array of instruction handles describing the matched area
    336     */
    337    public final Iterator<InstructionHandle[]> search(final String pattern, final InstructionHandle from, final CodeConstraint constraint) {
    338        final String search = compilePattern(pattern);
    339        int start = -1;
    340        for (int i = 0; i < handles.length; i++) {
    341            if (handles[i] == from) {
    342                start = i; // Where to start search from (index)
    343                break;
    344            }
    345        }
    346        if (start == -1) {
    347            throw new ClassGenException("Instruction handle " + from + " not found in instruction list.");
    348        }
    349        final Pattern regex = Pattern.compile(search);
    350        final List<InstructionHandle[]> matches = new ArrayList<>();
    351        final Matcher matcher = regex.matcher(ilString);
    352        while (start < ilString.length() && matcher.find(start)) {
    353            final int startExpr = matcher.start();
    354            final int endExpr = matcher.end();
    355            final int lenExpr = endExpr - startExpr;
    356            final InstructionHandle[] match = getMatch(startExpr, lenExpr);
    357            if (constraint == null || constraint.checkCode(match)) {
    358                matches.add(match);
    359            }
    360            start = endExpr;
    361        }
    362        return matches.iterator();
    363    }
    364
    365    /*
    366     * Internal debugging routines.
    367     */
    368//    private static final String pattern2string( String pattern ) {
    369//        return pattern2string(pattern, true);
    370//    }
    371
    372//    private static final String pattern2string( String pattern, boolean make_string ) {
    373//        StringBuilder buf = new StringBuilder();
    374//        for (int i = 0; i < pattern.length(); i++) {
    375//            char ch = pattern.charAt(i);
    376//            if (ch >= OFFSET) {
    377//                if (make_string) {
    378//                    buf.append(Constants.getOpcodeName(ch - OFFSET));
    379//                } else {
    380//                    buf.append((ch - OFFSET));
    381//                }
    382//            } else {
    383//                buf.append(ch);
    384//            }
    385//        }
    386//        return buf.toString();
    387//    }
    388}