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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