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1 package org.apache.bcel.util; 2 3 /* ==================================================================== 4 * The Apache Software License, Version 1.1 5 * 6 * Copyright (c) 2001 The Apache Software Foundation. All rights 7 * reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 21 * 3. The end-user documentation included with the redistribution, 22 * if any, must include the following acknowledgment: 23 * "This product includes software developed by the 24 * Apache Software Foundation (http://www.apache.org/)." 25 * Alternately, this acknowledgment may appear in the software itself, 26 * if and wherever such third-party acknowledgments normally appear. 27 * 28 * 4. The names "Apache" and "Apache Software Foundation" and 29 * "Apache BCEL" must not be used to endorse or promote products 30 * derived from this software without prior written permission. For 31 * written permission, please contact apache@apache.org. 32 * 33 * 5. Products derived from this software may not be called "Apache", 34 * "Apache BCEL", nor may "Apache" appear in their name, without 35 * prior written permission of the Apache Software Foundation. 36 * 37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR 41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 * ==================================================================== 50 * 51 * This software consists of voluntary contributions made by many 52 * individuals on behalf of the Apache Software Foundation. For more 53 * information on the Apache Software Foundation, please see 54 * <http://www.apache.org/>;. 55 */ 56 57 import java.util.*; 58 import org.apache.bcel.Constants; 59 import org.apache.bcel.generic.*; 60 import org.apache.regexp.*; 61 62 /*** 63 * InstructionFinder is a tool to search for given instructions patterns, 64 * i.e., match sequences of instructions in an instruction list via 65 * regular expressions. This can be used, e.g., in order to implement 66 * a peep hole optimizer that looks for code patterns and replaces 67 * them with faster equivalents. 68 * 69 * <p>This class internally uses the <a href="http://jakarta.apache.org/regexp/"> 70 * Regexp</a> package to search for regular expressions. 71 * 72 * A typical application would look like this: 73 <pre> 74 InstructionFinder f = new InstructionFinder(il); 75 String pat = "IfInstruction ICONST_0 GOTO ICONST_1 NOP (IFEQ|IFNE)"; 76 77 for(Iterator i = f.search(pat, constraint); i.hasNext(); ) { 78 InstructionHandle[] match = (InstructionHandle[])i.next(); 79 ... 80 il.delete(match[1], match[5]); 81 ... 82 } 83 </pre> 84 * @version $Id: InstructionFinder.java,v 1.1.1.1 2001/10/29 20:00:30 jvanzyl Exp $ 85 * @author <A HREF="http://www.berlin.de/~markus.dahm/">M. Dahm</A> 86 * @see Instruction 87 * @see InstructionList 88 */ 89 public class InstructionFinder { 90 private static final int OFFSET = 32767; // char + OFFSET is outside of LATIN-1 91 private static final int NO_OPCODES = 256; // Potential number, some are not used 92 93 private static final HashMap map = new HashMap(); // Map<String,Pattern> 94 95 private InstructionList il; 96 private String il_string; // instruction list as string 97 private InstructionHandle[] handles; // map instruction list to array 98 99 /*** 100 * @param il instruction list to search for given patterns 101 */ 102 public InstructionFinder(InstructionList il) { 103 this.il = il; 104 reread(); 105 } 106 107 /*** 108 * Reread the instruction list, e.g., after you've altered the list upon a match. 109 */ 110 public final void reread() { 111 int size = il.getLength(); 112 char[] buf = new char[size]; // Create a string with length equal to il length 113 handles = il.getInstructionHandles(); 114 115 // Map opcodes to characters 116 for(int i=0; i < size; i++) 117 buf[i] = makeChar(handles[i].getInstruction().getOpcode()); 118 119 il_string = new String(buf); 120 } 121 122 /*** 123 * Map symbolic instruction names like "getfield" to a single character. 124 * 125 * @param pattern instruction pattern in lower case 126 * @return encoded string for a pattern such as "BranchInstruction". 127 */ 128 private static final String mapName(String pattern) { 129 String result = (String)map.get(pattern); 130 131 if(result != null) 132 return result; 133 134 for(short i=0; i < NO_OPCODES; i++) 135 if(pattern.equals(Constants.OPCODE_NAMES[i])) 136 return "" + makeChar(i); 137 138 throw new RuntimeException("Instruction unknown: " + pattern); 139 } 140 141 /*** 142 * Replace symbolic names of instructions with the appropiate character and remove 143 * all white space from string. Meta characters such as +, * are ignored. 144 * 145 * @param pattern The pattern to compile 146 * @return translated regular expression string 147 */ 148 private static final String compilePattern(String pattern) { 149 String lower = pattern.toLowerCase(); 150 StringBuffer buf = new StringBuffer(); 151 int size = pattern.length(); 152 153 for(int i=0; i < size; i++) { 154 char ch = lower.charAt(i); 155 156 if(Character.isLetterOrDigit(ch)) { 157 StringBuffer name = new StringBuffer(); 158 159 while((Character.isLetterOrDigit(ch) || ch == '_') && i < size) { 160 name.append(ch); 161 162 if(++i < size) 163 ch = lower.charAt(i); 164 else 165 break; 166 } 167 168 i--; 169 170 buf.append(mapName(name.toString())); 171 } else if(!Character.isWhitespace(ch)) 172 buf.append(ch); 173 } 174 175 return buf.toString(); 176 } 177 178 /*** 179 * @return the matched piece of code as an array of instruction (handles) 180 */ 181 private InstructionHandle[] getMatch(int matched_from, int match_length) { 182 InstructionHandle[] match = new InstructionHandle[match_length]; 183 System.arraycopy(handles, matched_from, match, 0, match_length); 184 185 return match; 186 } 187 188 /*** 189 * Search for the given pattern in the instruction list. You can search for any valid 190 * opcode via its symbolic name, e.g. "istore". You can also use a super class or 191 * an interface name to match a whole set of instructions, e.g. "BranchInstruction" or 192 * "LoadInstruction". "istore" is also an alias for all "istore_x" instructions. Additional 193 * aliases are "if" for "ifxx", "if_icmp" for "if_icmpxx", "if_acmp" for "if_acmpxx". 194 * 195 * Consecutive instruction names must be separated by white space which will be removed 196 * during the compilation of the pattern. 197 * 198 * For the rest the usual pattern matching rules for regular expressions apply.<P> 199 * Example pattern: 200 * <pre> 201 search("BranchInstruction NOP ((IfInstruction|GOTO)+ ISTORE Instruction)*"); 202 * </pre> 203 * 204 * <p>If you alter the instruction list upon a match such that other 205 * matching areas are affected, you should call reread() to update 206 * the finder and call search() again, because the matches are cached. 207 * 208 * @param pattern the instruction pattern to search for, where case is ignored 209 * @param from where to start the search in the instruction list 210 * @param constraint optional CodeConstraint to check the found code pattern for 211 * user-defined constraints 212 * @return iterator of matches where e.nextElement() returns an array of instruction handles 213 * describing the matched area 214 */ 215 public final Iterator search(String pattern, InstructionHandle from, 216 CodeConstraint constraint) 217 { 218 String search = compilePattern(pattern); 219 int start = -1; 220 221 for(int i=0; i < handles.length; i++) { 222 if(handles[i] == from) { 223 start = i; // Where to start search from (index) 224 break; 225 } 226 } 227 228 if(start == -1) 229 throw new ClassGenException("Instruction handle " + from + 230 " not found in instruction list."); 231 try { 232 RE regex = new RE(search); 233 ArrayList matches = new ArrayList(); 234 235 while(start < il_string.length() && regex.match(il_string, start)) { 236 int startExpr = regex.getParenStart(0); 237 int endExpr = regex.getParenEnd(0); 238 int lenExpr = regex.getParenLength(0); 239 240 InstructionHandle[] match = getMatch(startExpr, lenExpr); 241 242 if((constraint == null) || constraint.checkCode(match)) 243 matches.add(match); 244 start = endExpr; 245 } 246 247 return matches.iterator(); 248 } catch(RESyntaxException e) { 249 System.err.println(e); 250 } 251 252 return null; 253 } 254 255 /*** 256 * Start search beginning from the start of the given instruction list. 257 * 258 * @param pattern the instruction pattern to search for, where case is ignored 259 * @return iterator of matches where e.nextElement() 260 * returns an array of instruction handles describing the matched 261 * area 262 */ 263 public final Iterator search(String pattern) { 264 return search(pattern, il.getStart(), null); 265 } 266 267 /*** 268 * Start search beginning from `from'. 269 * 270 * @param pattern the instruction pattern to search for, where case is ignored 271 * @param from where to start the search in the instruction list 272 * @return iterator of matches where e.nextElement() returns an array of instruction handles 273 * describing the matched area 274 */ 275 public final Iterator search(String pattern, InstructionHandle from) { 276 return search(pattern, from, null); 277 } 278 279 /*** 280 * Start search beginning from the start of the given instruction list. 281 * Check found matches with the constraint object. 282 * 283 * @param pattern the instruction pattern to search for, case is ignored 284 * @param constraint constraints to be checked on matching code 285 * @return instruction handle or `null' if the match failed 286 */ 287 public final Iterator search(String pattern, CodeConstraint constraint) { 288 return search(pattern, il.getStart(), constraint); 289 } 290 291 /*** 292 * Convert opcode number to char. 293 */ 294 private static final char makeChar(short opcode) { 295 return (char)(opcode + OFFSET); 296 } 297 298 /*** 299 * @return the inquired instruction list 300 */ 301 public final InstructionList getInstructionList() { return il; } 302 303 /*** 304 * Code patterns found may be checked using an additional 305 * user-defined constraint object whether they really match the needed criterion. 306 * I.e., check constraints that can not expressed with regular expressions. 307 * 308 */ 309 public interface CodeConstraint { 310 /*** 311 * @param match array of instructions matching the requested pattern 312 * @return true if the matched area is really useful 313 */ 314 public boolean checkCode(InstructionHandle[] match); 315 } 316 317 // Initialize pattern map 318 319 static { 320 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)"); 321 map.put("invokeinstruction", "(invokevirtual|invokeinterface|invokestatic|invokespecial)"); 322 map.put("arrayinstruction", "(baload|aastore|saload|caload|fastore|lastore|iaload|castore|iastore|aaload|bastore|sastore|faload|laload|daload|dastore)"); 323 map.put("gotoinstruction", "(goto|goto_w)"); 324 map.put("conversioninstruction", "(d2l|l2d|i2s|d2i|l2i|i2b|l2f|d2f|f2i|i2d|i2l|f2d|i2c|f2l|i2f)"); 325 map.put("localvariableinstruction", "(fstore|iinc|lload|dstore|dload|iload|aload|astore|istore|fload|lstore)"); 326 map.put("loadinstruction", "(fload|dload|lload|iload|aload)"); 327 map.put("fieldinstruction", "(getfield|putstatic|getstatic|putfield)"); 328 map.put("cpinstruction", "(ldc2_w|invokeinterface|multianewarray|putstatic|instanceof|getstatic|checkcast|getfield|invokespecial|ldc_w|invokestatic|invokevirtual|putfield|ldc|new|anewarray)"); 329 map.put("stackinstruction", "(dup2|swap|dup2_x2|pop|pop2|dup|dup2_x1|dup_x2|dup_x1)"); 330 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)"); 331 map.put("returninstruction", "(lreturn|ireturn|freturn|dreturn|areturn|return)"); 332 map.put("storeinstruction", "(istore|fstore|dstore|astore|lstore)"); 333 map.put("select", "(tableswitch|lookupswitch)"); 334 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)"); 335 map.put("jsrinstruction", "(jsr|jsr_w)"); 336 map.put("variablelengthinstruction", "(tableswitch|jsr|goto|lookupswitch)"); 337 map.put("unconditionalbranch", "(goto|jsr|jsr_w|athrow|goto_w)"); 338 map.put("constantpushinstruction", "(dconst|bipush|sipush|fconst|iconst|lconst)"); 339 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)"); 340 map.put("popinstruction", "(fstore|dstore|pop|pop2|astore|putstatic|istore|lstore)"); 341 map.put("allocationinstruction", "(multianewarray|new|anewarray|newarray)"); 342 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)"); 343 map.put("pushinstruction", "(dup|lload|dup2|bipush|fload|ldc2_w|sipush|lconst|fconst|dload|getstatic|ldc_w|aconst_null|dconst|iload|ldc|iconst|aload)"); 344 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)"); 345 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)"); 346 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)"); 347 map.put("loadclass", "(multianewarray|invokeinterface|instanceof|invokespecial|putfield|checkcast|putstatic|invokevirtual|new|getstatic|invokestatic|getfield|anewarray)"); 348 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)"); 349 350 // Some aliases 351 map.put("if_icmp", "(if_icmpne|if_icmpeq|if_icmple|if_icmpge|if_icmplt|if_icmpgt)"); 352 map.put("if_acmp", "(if_acmpeq|if_acmpne)"); 353 map.put("if", "(ifeq|ifne|iflt|ifge|ifgt|ifle)"); 354 355 // Precompile some aliases first 356 map.put("iconst", precompile(Constants.ICONST_0, Constants.ICONST_5, Constants.ICONST_M1)); 357 map.put("lconst", new String(new char[] { '(', makeChar(Constants.LCONST_0), '|', 358 makeChar(Constants.LCONST_1), ')' })); 359 map.put("dconst", new String(new char[] { '(', makeChar(Constants.DCONST_0), '|', 360 makeChar(Constants.DCONST_1), ')' })); 361 map.put("fconst", new String(new char[] { '(', makeChar(Constants.FCONST_0), '|', 362 makeChar(Constants.FCONST_1), ')' })); 363 364 map.put("iload", precompile(Constants.ILOAD_0, Constants.ILOAD_3, Constants.ILOAD)); 365 map.put("dload", precompile(Constants.DLOAD_0, Constants.DLOAD_3, Constants.DLOAD)); 366 map.put("fload", precompile(Constants.FLOAD_0, Constants.FLOAD_3, Constants.FLOAD)); 367 map.put("aload", precompile(Constants.ALOAD_0, Constants.ALOAD_3, Constants.ALOAD)); 368 369 map.put("istore", precompile(Constants.ISTORE_0, Constants.ISTORE_3, Constants.ISTORE)); 370 map.put("dstore", precompile(Constants.DSTORE_0, Constants.DSTORE_3, Constants.DSTORE)); 371 map.put("fstore", precompile(Constants.FSTORE_0, Constants.FSTORE_3, Constants.FSTORE)); 372 map.put("astore", precompile(Constants.ASTORE_0, Constants.ASTORE_3, Constants.ASTORE)); 373 374 // Compile strings 375 376 for(Iterator i = map.keySet().iterator(); i.hasNext(); ) { 377 String key = (String)i.next(); 378 String value = (String)map.get(key); 379 380 char ch = value.charAt(1); // Omit already precompiled patterns 381 if(ch < OFFSET) { 382 map.put(key, compilePattern(value)); // precompile all patterns 383 } 384 } 385 386 // Add instruction alias to match anything 387 388 StringBuffer buf = new StringBuffer("("); 389 390 for(short i=0; i < NO_OPCODES; i++) { 391 if(Constants.NO_OF_OPERANDS[i] != Constants.UNDEFINED) { // Not an invalid opcode 392 buf.append(makeChar(i)); 393 394 if(i < NO_OPCODES - 1) 395 buf.append('|'); 396 } 397 } 398 buf.append(')'); 399 400 map.put("instruction", buf.toString()); 401 } 402 403 private static String precompile(short from, short to, short extra) { 404 StringBuffer buf = new StringBuffer("("); 405 406 for(short i=from; i <= to; i++) { 407 buf.append(makeChar(i)); 408 buf.append('|'); 409 } 410 411 buf.append(makeChar(extra)); 412 buf.append(")"); 413 return buf.toString(); 414 } 415 416 /* 417 * Internal debugging routines. 418 */ 419 private static final String pattern2string(String pattern) { 420 return pattern2string(pattern, true); 421 } 422 423 private static final String pattern2string(String pattern, boolean make_string) { 424 StringBuffer buf = new StringBuffer(); 425 426 for(int i=0; i < pattern.length(); i++) { 427 char ch = pattern.charAt(i); 428 429 if(ch >= OFFSET) { 430 if(make_string) 431 buf.append(Constants.OPCODE_NAMES[ch - OFFSET]); 432 else 433 buf.append((int)(ch - OFFSET)); 434 } else 435 buf.append(ch); 436 } 437 438 return buf.toString(); 439 } 440 }

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