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