    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 *
    017 */
    018package org.apache.bcel.util;
    019
    020import java.util.ArrayList;
    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.,
    036 * match sequences of instructions in an instruction list via regular
    037 * expressions. This can be used, e.g., in order to implement a peep hole
    038 * optimizer that looks for code patterns and replaces them with faster
    039 * equivalents.
    040 *
    041 * <p>
    042 * This class internally uses the java.util.regex
    043 * package to search for regular expressions.
    044 *
    045 * A typical application would look like this:
    046 *
    047 * <pre>
    048 *
    049 *
    050 *   InstructionFinder f   = new InstructionFinder(il);
    051 *   String            pat = &quot;IfInstruction ICONST_0 GOTO ICONST_1 NOP (IFEQ|IFNE)&quot;;
    052 *
    053 *   for (Iterator i = f.search(pat, constraint); i.hasNext(); ) {
    054 *   InstructionHandle[] match = (InstructionHandle[])i.next();
    055 *   ...
    056 *   il.delete(match[1], match[5]);
    057 *   ...
    058 *   }
    059 *
    060 *
    061 * </pre>
    062 *
    063 * @version $Id$
    064 * @see org.apache.bcel.generic.Instruction
    065 * @see InstructionList
    066 */
    067public class InstructionFinder {
    068
    069    private static final int OFFSET = 32767; // char + OFFSET is outside of LATIN-1
    070    private static final int NO_OPCODES = 256; // Potential number, some are not used
    071    private static final Map<String, String> map = new HashMap<>();
    072    private final InstructionList il;
    073    private String il_string; // instruction list as string
    074    private InstructionHandle[] handles; // map instruction
    075
    076
    077    // list to array
    078    /**
    079     * @param il
    080     *          instruction list to search for given patterns
    081     */
    082    public InstructionFinder(final InstructionList il) {
    083        this.il = il;
    084        reread();
    085    }
    086
    087
    088    /**
    089     * Reread the instruction list, e.g., after you've altered the list upon a
    090     * match.
    091     */
    092    public final void reread() {
    093        final int size = il.getLength();
    094        final char[] buf = new char[size]; // Create a string with length equal to il length
    095        handles = il.getInstructionHandles();
    096        // Map opcodes to characters
    097        for (int i = 0; i < size; i++) {
    098            buf[i] = makeChar(handles[i].getInstruction().getOpcode());
    099        }
    100        il_string = new String(buf);
    101    }
    102
    103
    104    /**
    105     * Map symbolic instruction names like "getfield" to a single character.
    106     *
    107     * @param pattern
    108     *          instruction pattern in lower case
    109     * @return encoded string for a pattern such as "BranchInstruction".
    110     */
    111    private static String mapName( final String pattern ) {
    112        final String result = map.get(pattern);
    113        if (result != null) {
    114            return result;
    115        }
    116        for (short i = 0; i < NO_OPCODES; i++) {
    117            if (pattern.equals(Const.getOpcodeName(i))) {
    118                return "" + makeChar(i);
    119            }
    120        }
    121        throw new RuntimeException("Instruction unknown: " + pattern);
    122    }
    123
    124
    125    /**
    126     * Replace symbolic names of instructions with the appropiate character and
    127     * remove all white space from string. Meta characters such as +, * are
    128     * ignored.
    129     *
    130     * @param pattern
    131     *          The pattern to compile
    132     * @return translated regular expression string
    133     */
    134    private static String compilePattern( final String pattern ) {
    135        //Bug: BCEL-77 - Instructions are assumed to be english, to avoid odd Locale issues
    136        final String lower = pattern.toLowerCase(Locale.ENGLISH);
    137        final StringBuilder buf = new StringBuilder();
    138        final int size = pattern.length();
    139        for (int i = 0; i < size; i++) {
    140            char ch = lower.charAt(i);
    141            if (Character.isLetterOrDigit(ch)) {
    142                final StringBuilder name = new StringBuilder();
    143                while ((Character.isLetterOrDigit(ch) || ch == '_') && i < size) {
    144                    name.append(ch);
    145                    if (++i < size) {
    146                        ch = lower.charAt(i);
    147                    } else {
    148                        break;
    149                    }
    150                }
    151                i--;
    152                buf.append(mapName(name.toString()));
    153            } else if (!Character.isWhitespace(ch)) {
    154                buf.append(ch);
    155            }
    156        }
    157        return buf.toString();
    158    }
    159
    160
    161    /**
    162     * @return the matched piece of code as an array of instruction (handles)
    163     */
    164    private InstructionHandle[] getMatch( final int matched_from, final int match_length ) {
    165        final InstructionHandle[] match = new InstructionHandle[match_length];
    166        System.arraycopy(handles, matched_from, match, 0, match_length);
    167        return match;
    168    }
    169
    170
    171    /**
    172     * Search for the given pattern in the instruction list. You can search for
    173     * any valid opcode via its symbolic name, e.g. "istore". You can also use a
    174     * super class or an interface name to match a whole set of instructions, e.g.
    175     * "BranchInstruction" or "LoadInstruction". "istore" is also an alias for all
    176     * "istore_x" instructions. Additional aliases are "if" for "ifxx", "if_icmp"
    177     * for "if_icmpxx", "if_acmp" for "if_acmpxx".
    178     *
    179     * Consecutive instruction names must be separated by white space which will
    180     * be removed during the compilation of the pattern.
    181     *
    182     * For the rest the usual pattern matching rules for regular expressions
    183     * apply.
    184     * <P>
    185     * Example pattern:
    186     *
    187     * <pre>
    188     * search(&quot;BranchInstruction NOP ((IfInstruction|GOTO)+ ISTORE Instruction)*&quot;);
    189     * </pre>
    190     *
    191     * <p>
    192     * If you alter the instruction list upon a match such that other matching
    193     * areas are affected, you should call reread() to update the finder and call
    194     * search() again, because the matches are cached.
    195     *
    196     * @param pattern
    197     *          the instruction pattern to search for, where case is ignored
    198     * @param from
    199     *          where to start the search in the instruction list
    200     * @param constraint
    201     *          optional CodeConstraint to check the found code pattern for
    202     *          user-defined constraints
    203     * @return iterator of matches where e.nextElement() returns an array of
    204     *         instruction handles describing the matched area
    205     */
    206    public final Iterator<InstructionHandle[]> search( final String pattern, final InstructionHandle from, final CodeConstraint constraint ) {
    207        final String search = compilePattern(pattern);
    208        int start = -1;
    209        for (int i = 0; i < handles.length; i++) {
    210            if (handles[i] == from) {
    211                start = i; // Where to start search from (index)
    212                break;
    213            }
    214        }
    215        if (start == -1) {
    216            throw new ClassGenException("Instruction handle " + from
    217                    + " not found in instruction list.");
    218        }
    219        final Pattern regex = Pattern.compile(search);
    220        final List<InstructionHandle[]> matches = new ArrayList<>();
    221        final Matcher matcher = regex.matcher(il_string);
    222        while (start < il_string.length() && matcher.find(start)) {
    223            final int startExpr = matcher.start();
    224            final int endExpr = matcher.end();
    225            final int lenExpr = endExpr - startExpr;
    226            final InstructionHandle[] match = getMatch(startExpr, lenExpr);
    227            if ((constraint == null) || constraint.checkCode(match)) {
    228                matches.add(match);
    229            }
    230            start = endExpr;
    231        }
    232        return matches.iterator();
    233    }
    234
    235
    236    /**
    237     * Start search beginning from the start of the given instruction list.
    238     *
    239     * @param pattern
    240     *          the instruction pattern to search for, where case is ignored
    241     * @return iterator of matches where e.nextElement() returns an array of
    242     *         instruction handles describing the matched area
    243     */
    244    public final Iterator<InstructionHandle[]> search( final String pattern ) {
    245        return search(pattern, il.getStart(), null);
    246    }
    247
    248
    249    /**
    250     * Start search beginning from `from'.
    251     *
    252     * @param pattern
    253     *          the instruction pattern to search for, where case is ignored
    254     * @param from
    255     *          where to start the search in the instruction list
    256     * @return iterator of matches where e.nextElement() returns an array of
    257     *         instruction handles describing the matched area
    258     */
    259    public final Iterator<InstructionHandle[]> search( final String pattern, final InstructionHandle from ) {
    260        return search(pattern, from, null);
    261    }
    262
    263
    264    /**
    265     * Start search beginning from the start of the given instruction list. Check
    266     * found matches with the constraint object.
    267     *
    268     * @param pattern
    269     *          the instruction pattern to search for, case is ignored
    270     * @param constraint
    271     *          constraints to be checked on matching code
    272     * @return instruction handle or `null' if the match failed
    273     */
    274    public final Iterator<InstructionHandle[]> search( final String pattern, final CodeConstraint constraint ) {
    275        return search(pattern, il.getStart(), constraint);
    276    }
    277
    278
    279    /**
    280     * Convert opcode number to char.
    281     */
    282    private static char makeChar( final short opcode ) {
    283        return (char) (opcode + OFFSET);
    284    }
    285
    286
    287    /**
    288     * @return the inquired instruction list
    289     */
    290    public final InstructionList getInstructionList() {
    291        return il;
    292    }
    293
    294    /**
    295     * Code patterns found may be checked using an additional user-defined
    296     * constraint object whether they really match the needed criterion. I.e.,
    297     * check constraints that can not expressed with regular expressions.
    298     *
    299     */
    300    public interface CodeConstraint {
    301
    302        /**
    303         * @param match
    304         *          array of instructions matching the requested pattern
    305         * @return true if the matched area is really useful
    306         */
    307        boolean checkCode( InstructionHandle[] match );
    308    }
    309
    310    // Initialize pattern map
    311    static {
    312        map.put("arithmeticinstruction","(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)");
    313        map.put("invokeinstruction", "(invokevirtual|invokeinterface|invokestatic|invokespecial|invokedynamic)");
    314        map.put("arrayinstruction", "(baload|aastore|saload|caload|fastore|lastore|iaload|castore|iastore|aaload|bastore|sastore|faload|laload|daload|dastore)");
    315        map.put("gotoinstruction", "(goto|goto_w)");
    316        map.put("conversioninstruction", "(d2l|l2d|i2s|d2i|l2i|i2b|l2f|d2f|f2i|i2d|i2l|f2d|i2c|f2l|i2f)");
    317        map.put("localvariableinstruction","(fstore|iinc|lload|dstore|dload|iload|aload|astore|istore|fload|lstore)");
    318        map.put("loadinstruction", "(fload|dload|lload|iload|aload)");
    319        map.put("fieldinstruction", "(getfield|putstatic|getstatic|putfield)");
    320        map.put("cpinstruction", "(ldc2_w|invokeinterface|invokedynamic|multianewarray|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|ldc_w|invokestatic|invokevirtual|putfield|ldc|new|anewarray)");
    321        map.put("stackinstruction", "(dup2|swap|dup2_x2|pop|pop2|dup|dup2_x1|dup_x2|dup_x1)");
    322        map.put("branchinstruction", "(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)");
    323        map.put("returninstruction", "(lreturn|ireturn|freturn|dreturn|areturn|return)");
    324        map.put("storeinstruction", "(istore|fstore|dstore|astore|lstore)");
    325        map.put("select", "(tableswitch|lookupswitch)");
    326        map.put("ifinstruction", "(ifeq|ifgt|if_icmpne|if_icmpeq|ifge|ifnull|ifne|if_icmple|if_icmpge|if_acmpeq|if_icmplt|if_acmpne|ifnonnull|iflt|if_icmpgt|ifle)");
    327        map.put("jsrinstruction", "(jsr|jsr_w)");
    328        map.put("variablelengthinstruction", "(tableswitch|jsr|goto|lookupswitch)");
    329        map.put("unconditionalbranch", "(goto|jsr|jsr_w|athrow|goto_w)");
    330        map.put("constantpushinstruction", "(dconst|bipush|sipush|fconst|iconst|lconst)");
    331        map.put("typedinstruction", "(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)");
    332        map.put("popinstruction", "(fstore|dstore|pop|pop2|astore|putstatic|istore|lstore)");
    333        map.put("allocationinstruction", "(multianewarray|new|anewarray|newarray)");
    334        map.put("indexedinstruction", "(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)");
    335        map.put("pushinstruction", "(dup|lload|dup2|bipush|fload|ldc2_w|sipush|lconst|fconst|dload|getstatic|ldc_w|aconst_null|dconst|iload|ldc|iconst|aload)");
    336        map.put("stackproducer", "(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)");
    337        map.put("stackconsumer", "(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)");
    338        map.put("exceptionthrower","(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)");
    339        map.put("loadclass", "(multianewarray|invokeinterface|invokedynamic|instanceof|invokespecial|putfield|checkcast|putstatic|invokevirtual|new|getstatic|invokestatic|getfield|anewarray)");
    340        map.put("instructiontargeter", "(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)");
    341        // Some aliases
    342        map.put("if_icmp", "(if_icmpne|if_icmpeq|if_icmple|if_icmpge|if_icmplt|if_icmpgt)");
    343        map.put("if_acmp", "(if_acmpeq|if_acmpne)");
    344        map.put("if", "(ifeq|ifne|iflt|ifge|ifgt|ifle)");
    345        // Precompile some aliases first
    346        map.put("iconst", precompile(Const.ICONST_0, Const.ICONST_5, Const.ICONST_M1));
    347        map.put("lconst", new String(new char[] { '(', makeChar(Const.LCONST_0), '|', makeChar(Const.LCONST_1), ')' }));
    348        map.put("dconst", new String(new char[] { '(', makeChar(Const.DCONST_0), '|', makeChar(Const.DCONST_1), ')' }));
    349        map.put("fconst", new String(new char[] { '(', makeChar(Const.FCONST_0), '|', makeChar(Const.FCONST_1), '|', makeChar(Const.FCONST_2), ')' }));
    350        map.put("lload", precompile(Const.LLOAD_0, Const.LLOAD_3, Const.LLOAD));
    351        map.put("iload", precompile(Const.ILOAD_0, Const.ILOAD_3, Const.ILOAD));
    352        map.put("dload", precompile(Const.DLOAD_0, Const.DLOAD_3, Const.DLOAD));
    353        map.put("fload", precompile(Const.FLOAD_0, Const.FLOAD_3, Const.FLOAD));
    354        map.put("aload", precompile(Const.ALOAD_0, Const.ALOAD_3, Const.ALOAD));
    355        map.put("lstore", precompile(Const.LSTORE_0, Const.LSTORE_3, Const.LSTORE));
    356        map.put("istore", precompile(Const.ISTORE_0, Const.ISTORE_3, Const.ISTORE));
    357        map.put("dstore", precompile(Const.DSTORE_0, Const.DSTORE_3, Const.DSTORE));
    358        map.put("fstore", precompile(Const.FSTORE_0, Const.FSTORE_3, Const.FSTORE));
    359        map.put("astore", precompile(Const.ASTORE_0, Const.ASTORE_3, Const.ASTORE));
    360        // Compile strings
    361        for (final Map.Entry<String, String> entry : map.entrySet()) {
    362            final String key = entry.getKey();
    363            final String value = entry.getValue();
    364            final char ch = value.charAt(1); // Omit already precompiled patterns
    365            if (ch < OFFSET) {
    366                map.put(key, compilePattern(value)); // precompile all patterns
    367            }
    368        }
    369        // Add instruction alias to match anything
    370        final StringBuilder buf = new StringBuilder("(");
    371        for (short i = 0; i < NO_OPCODES; i++) {
    372            if (Const.getNoOfOperands(i) != Const.UNDEFINED) { // Not an invalid opcode
    373                buf.append(makeChar(i));
    374                if (i < NO_OPCODES - 1) {
    375                    buf.append('|');
    376                }
    377            }
    378        }
    379        buf.append(')');
    380        map.put("instruction", buf.toString());
    381    }
    382
    383
    384    private static String precompile( final short from, final short to, final short extra ) {
    385        final StringBuilder buf = new StringBuilder("(");
    386        for (short i = from; i <= to; i++) {
    387            buf.append(makeChar(i));
    388            buf.append('|');
    389        }
    390        buf.append(makeChar(extra));
    391        buf.append(")");
    392        return buf.toString();
    393    }
    394
    395
    396    /*
    397     * Internal debugging routines.
    398     */
    399//    private static final String pattern2string( String pattern ) {
    400//        return pattern2string(pattern, true);
    401//    }
    402
    403
    404//    private static final String pattern2string( String pattern, boolean make_string ) {
    405//        StringBuffer buf = new StringBuffer();
    406//        for (int i = 0; i < pattern.length(); i++) {
    407//            char ch = pattern.charAt(i);
    408//            if (ch >= OFFSET) {
    409//                if (make_string) {
    410//                    buf.append(Constants.getOpcodeName(ch - OFFSET));
    411//                } else {
    412//                    buf.append((ch - OFFSET));
    413//                }
    414//            } else {
    415//                buf.append(ch);
    416//            }
    417//        }
    418//        return buf.toString();
    419//    }
    420}