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