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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.bcel.util;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.bcel.Constants;
import org.apache.bcel.generic.ClassGenException;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionList;
/**
* InstructionFinder is a tool to search for given instructions patterns, i.e.,
* match sequences of instructions in an instruction list via regular
* expressions. This can be used, e.g., in order to implement a peep hole
* optimizer that looks for code patterns and replaces them with faster
* equivalents.
*
* <p>
* This class internally uses the java.util.regex
* package to search for regular expressions.
*
* A typical application would look like this:
*
* <pre>
*
*
* InstructionFinder f = new InstructionFinder(il);
* String pat = "IfInstruction ICONST_0 GOTO ICONST_1 NOP (IFEQ|IFNE)";
*
* for(Iterator i = f.search(pat, constraint); i.hasNext(); ) {
* InstructionHandle[] match = (InstructionHandle[])i.next();
* ...
* il.delete(match[1], match[5]);
* ...
* }
*
*
* </pre>
*
* @version $Id$
* @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
* @see Instruction
* @see InstructionList
*/
public class InstructionFinder {
private static final int OFFSET = 32767; // char + OFFSET is
// outside of
// LATIN-1
private static final int NO_OPCODES = 256; // Potential number,
// some are not used
private static final Map<String, String> map = new HashMap<String, String>();
private InstructionList il;
private String il_string; // instruction list
// as string
private InstructionHandle[] handles; // map instruction
// list to array
/**
* @param il
* instruction list to search for given patterns
*/
public InstructionFinder(InstructionList il) {
this.il = il;
reread();
}
/**
* Reread the instruction list, e.g., after you've altered the list upon a
* match.
*/
public final void reread() {
int size = il.getLength();
char[] buf = new char[size]; // Create a string with length equal to il
// length
handles = il.getInstructionHandles();
// Map opcodes to characters
for (int i = 0; i < size; i++) {
buf[i] = makeChar(handles[i].getInstruction().getOpcode());
}
il_string = new String(buf);
}
/**
* Map symbolic instruction names like "getfield" to a single character.
*
* @param pattern
* instruction pattern in lower case
* @return encoded string for a pattern such as "BranchInstruction".
*/
private static String mapName( String pattern ) {
String result = map.get(pattern);
if (result != null) {
return result;
}
for (short i = 0; i < NO_OPCODES; i++) {
if (pattern.equals(Constants.OPCODE_NAMES[i])) {
return "" + makeChar(i);
}
}
throw new RuntimeException("Instruction unknown: " + pattern);
}
/**
* Replace symbolic names of instructions with the appropiate character and
* remove all white space from string. Meta characters such as +, * are
* ignored.
*
* @param pattern
* The pattern to compile
* @return translated regular expression string
*/
private static String compilePattern( String pattern ) {
//Bug: 38787 - Instructions are assumed to be english, to avoid odd Locale issues
String lower = pattern.toLowerCase(Locale.ENGLISH);
StringBuilder buf = new StringBuilder();
int size = pattern.length();
for (int i = 0; i < size; i++) {
char ch = lower.charAt(i);
if (Character.isLetterOrDigit(ch)) {
StringBuilder name = new StringBuilder();
while ((Character.isLetterOrDigit(ch) || ch == '_') && i < size) {
name.append(ch);
if (++i < size) {
ch = lower.charAt(i);
} else {
break;
}
}
i--;
buf.append(mapName(name.toString()));
} else if (!Character.isWhitespace(ch)) {
buf.append(ch);
}
}
return buf.toString();
}
/**
* @return the matched piece of code as an array of instruction (handles)
*/
private InstructionHandle[] getMatch( int matched_from, int match_length ) {
InstructionHandle[] match = new InstructionHandle[match_length];
System.arraycopy(handles, matched_from, match, 0, match_length);
return match;
}
/**
* Search for the given pattern in the instruction list. You can search for
* any valid opcode via its symbolic name, e.g. "istore". You can also use a
* super class or an interface name to match a whole set of instructions, e.g.
* "BranchInstruction" or "LoadInstruction". "istore" is also an alias for all
* "istore_x" instructions. Additional aliases are "if" for "ifxx", "if_icmp"
* for "if_icmpxx", "if_acmp" for "if_acmpxx".
*
* Consecutive instruction names must be separated by white space which will
* be removed during the compilation of the pattern.
*
* For the rest the usual pattern matching rules for regular expressions
* apply.
* <P>
* Example pattern:
*
* <pre>
* search("BranchInstruction NOP ((IfInstruction|GOTO)+ ISTORE Instruction)*");
* </pre>
*
* <p>
* If you alter the instruction list upon a match such that other matching
* areas are affected, you should call reread() to update the finder and call
* search() again, because the matches are cached.
*
* @param pattern
* the instruction pattern to search for, where case is ignored
* @param from
* where to start the search in the instruction list
* @param constraint
* optional CodeConstraint to check the found code pattern for
* user-defined constraints
* @return iterator of matches where e.nextElement() returns an array of
* instruction handles describing the matched area
*/
public final Iterator<InstructionHandle[]> search( String pattern, InstructionHandle from, CodeConstraint constraint ) {
String search = compilePattern(pattern);
int start = -1;
for (int i = 0; i < handles.length; i++) {
if (handles[i] == from) {
start = i; // Where to start search from (index)
break;
}
}
if (start == -1) {
throw new ClassGenException("Instruction handle " + from
+ " not found in instruction list.");
}
Pattern regex = Pattern.compile(search);
List<InstructionHandle[]> matches = new ArrayList<InstructionHandle[]>();
Matcher matcher = regex.matcher(il_string);
while (start < il_string.length() && matcher.find(start)) {
int startExpr = matcher.start();
int endExpr = matcher.end();
int lenExpr = (endExpr - startExpr);
InstructionHandle[] match = getMatch(startExpr, lenExpr);
if ((constraint == null) || constraint.checkCode(match)) {
matches.add(match);
}
start = endExpr;
}
return matches.iterator();
}
/**
* Start search beginning from the start of the given instruction list.
*
* @param pattern
* the instruction pattern to search for, where case is ignored
* @return iterator of matches where e.nextElement() returns an array of
* instruction handles describing the matched area
*/
public final Iterator<InstructionHandle[]> search( String pattern ) {
return search(pattern, il.getStart(), null);
}
/**
* Start search beginning from `from'.
*
* @param pattern
* the instruction pattern to search for, where case is ignored
* @param from
* where to start the search in the instruction list
* @return iterator of matches where e.nextElement() returns an array of
* instruction handles describing the matched area
*/
public final Iterator<InstructionHandle[]> search( String pattern, InstructionHandle from ) {
return search(pattern, from, null);
}
/**
* Start search beginning from the start of the given instruction list. Check
* found matches with the constraint object.
*
* @param pattern
* the instruction pattern to search for, case is ignored
* @param constraint
* constraints to be checked on matching code
* @return instruction handle or `null' if the match failed
*/
public final Iterator<InstructionHandle[]> search( String pattern, CodeConstraint constraint ) {
return search(pattern, il.getStart(), constraint);
}
/**
* Convert opcode number to char.
*/
private static char makeChar( short opcode ) {
return (char) (opcode + OFFSET);
}
/**
* @return the inquired instruction list
*/
public final InstructionList getInstructionList() {
return il;
}
/**
* Code patterns found may be checked using an additional user-defined
* constraint object whether they really match the needed criterion. I.e.,
* check constraints that can not expressed with regular expressions.
*
*/
public static interface CodeConstraint {
/**
* @param match
* array of instructions matching the requested pattern
* @return true if the matched area is really useful
*/
public boolean checkCode( InstructionHandle[] match );
}
// Initialize pattern map
static {
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)");
map.put("invokeinstruction", "(invokevirtual|invokeinterface|invokestatic|invokespecial)");
map.put("arrayinstruction", "(baload|aastore|saload|caload|fastore|lastore|iaload|castore|iastore|aaload|bastore|sastore|faload|laload|daload|dastore)");
map.put("gotoinstruction", "(goto|goto_w)");
map.put("conversioninstruction", "(d2l|l2d|i2s|d2i|l2i|i2b|l2f|d2f|f2i|i2d|i2l|f2d|i2c|f2l|i2f)");
map.put("localvariableinstruction","(fstore|iinc|lload|dstore|dload|iload|aload|astore|istore|fload|lstore)");
map.put("loadinstruction", "(fload|dload|lload|iload|aload)");
map.put("fieldinstruction", "(getfield|putstatic|getstatic|putfield)");
map.put("cpinstruction", "(ldc2_w|invokeinterface|multianewarray|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|ldc_w|invokestatic|invokevirtual|putfield|ldc|new|anewarray)");
map.put("stackinstruction", "(dup2|swap|dup2_x2|pop|pop2|dup|dup2_x1|dup_x2|dup_x1)");
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)");
map.put("returninstruction", "(lreturn|ireturn|freturn|dreturn|areturn|return)");
map.put("storeinstruction", "(istore|fstore|dstore|astore|lstore)");
map.put("select", "(tableswitch|lookupswitch)");
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)");
map.put("jsrinstruction", "(jsr|jsr_w)");
map.put("variablelengthinstruction", "(tableswitch|jsr|goto|lookupswitch)");
map.put("unconditionalbranch", "(goto|jsr|jsr_w|athrow|goto_w)");
map.put("constantpushinstruction", "(dconst|bipush|sipush|fconst|iconst|lconst)");
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|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)");
map.put("popinstruction", "(fstore|dstore|pop|pop2|astore|putstatic|istore|lstore)");
map.put("allocationinstruction", "(multianewarray|new|anewarray|newarray)");
map.put("indexedinstruction", "(lload|lstore|fload|ldc2_w|invokeinterface|multianewarray|astore|dload|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|dstore|istore|iinc|ldc_w|ret|fstore|invokestatic|iload|putfield|invokevirtual|ldc|new|aload|anewarray)");
map.put("pushinstruction", "(dup|lload|dup2|bipush|fload|ldc2_w|sipush|lconst|fconst|dload|getstatic|ldc_w|aconst_null|dconst|iload|ldc|iconst|aload)");
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|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)");
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|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)");
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|ldc|invokestatic|daload)");
map.put("loadclass", "(multianewarray|invokeinterface|instanceof|invokespecial|putfield|checkcast|putstatic|invokevirtual|new|getstatic|invokestatic|getfield|anewarray)");
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)");
// Some aliases
map.put("if_icmp", "(if_icmpne|if_icmpeq|if_icmple|if_icmpge|if_icmplt|if_icmpgt)");
map.put("if_acmp", "(if_acmpeq|if_acmpne)");
map.put("if", "(ifeq|ifne|iflt|ifge|ifgt|ifle)");
// Precompile some aliases first
map.put("iconst", precompile(Constants.ICONST_0, Constants.ICONST_5, Constants.ICONST_M1));
map.put("lconst", new String(new char[] { '(', makeChar(Constants.LCONST_0), '|', makeChar(Constants.LCONST_1), ')' }));
map.put("dconst", new String(new char[] { '(', makeChar(Constants.DCONST_0), '|', makeChar(Constants.DCONST_1), ')' }));
map.put("fconst", new String(new char[] { '(', makeChar(Constants.FCONST_0), '|', makeChar(Constants.FCONST_1), ')' }));
map.put("iload", precompile(Constants.ILOAD_0, Constants.ILOAD_3, Constants.ILOAD));
map.put("dload", precompile(Constants.DLOAD_0, Constants.DLOAD_3, Constants.DLOAD));
map.put("fload", precompile(Constants.FLOAD_0, Constants.FLOAD_3, Constants.FLOAD));
map.put("aload", precompile(Constants.ALOAD_0, Constants.ALOAD_3, Constants.ALOAD));
map.put("istore", precompile(Constants.ISTORE_0, Constants.ISTORE_3, Constants.ISTORE));
map.put("dstore", precompile(Constants.DSTORE_0, Constants.DSTORE_3, Constants.DSTORE));
map.put("fstore", precompile(Constants.FSTORE_0, Constants.FSTORE_3, Constants.FSTORE));
map.put("astore", precompile(Constants.ASTORE_0, Constants.ASTORE_3, Constants.ASTORE));
// Compile strings
for (String key : map.keySet()) {
String value = map.get(key);
char ch = value.charAt(1); // Omit already precompiled patterns
if (ch < OFFSET) {
map.put(key, compilePattern(value)); // precompile all
// patterns
}
}
// Add instruction alias to match anything
StringBuilder buf = new StringBuilder("(");
for (short i = 0; i < NO_OPCODES; i++) {
if (Constants.NO_OF_OPERANDS[i] != Constants.UNDEFINED) { // Not
// an
// invalid
// opcode
buf.append(makeChar(i));
if (i < NO_OPCODES - 1) {
buf.append('|');
}
}
}
buf.append(')');
map.put("instruction", buf.toString());
}
private static String precompile( short from, short to, short extra ) {
StringBuilder buf = new StringBuilder("(");
for (short i = from; i <= to; i++) {
buf.append(makeChar(i));
buf.append('|');
}
buf.append(makeChar(extra));
buf.append(")");
return buf.toString();
}
/*
* Internal debugging routines.
*/
// private static final String pattern2string( String pattern ) {
// return pattern2string(pattern, true);
// }
// private static final String pattern2string( String pattern, boolean make_string ) {
// StringBuffer buf = new StringBuffer();
// for (int i = 0; i < pattern.length(); i++) {
// char ch = pattern.charAt(i);
// if (ch >= OFFSET) {
// if (make_string) {
// buf.append(Constants.OPCODE_NAMES[ch - OFFSET]);
// } else {
// buf.append((ch - OFFSET));
// }
// } else {
// buf.append(ch);
// }
// }
// return buf.toString();
// }
}
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