1 | /* |
2 | * Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved. |
3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 | * |
5 | * This code is free software; you can redistribute it and/or modify it |
6 | * under the terms of the GNU General Public License version 2 only, as |
7 | * published by the Free Software Foundation. Sun designates this |
8 | * particular file as subject to the "Classpath" exception as provided |
9 | * by Sun in the LICENSE file that accompanied this code. |
10 | * |
11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
14 | * version 2 for more details (a copy is included in the LICENSE file that |
15 | * accompanied this code). |
16 | * |
17 | * You should have received a copy of the GNU General Public License version |
18 | * 2 along with this work; if not, write to the Free Software Foundation, |
19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
20 | * |
21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
23 | * have any questions. |
24 | */ |
25 | |
26 | //todo: one might eliminate uninits.andSets when monotonic |
27 | |
28 | package com.sun.tools.javac.comp; |
29 | |
30 | import com.sun.tools.javac.code.*; |
31 | import com.sun.tools.javac.tree.*; |
32 | import com.sun.tools.javac.util.*; |
33 | import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition; |
34 | |
35 | import com.sun.tools.javac.code.Symbol.*; |
36 | import com.sun.tools.javac.tree.JCTree.*; |
37 | |
38 | import static com.sun.tools.javac.code.Flags.*; |
39 | import static com.sun.tools.javac.code.Kinds.*; |
40 | import static com.sun.tools.javac.code.TypeTags.*; |
41 | |
42 | /** This pass implements dataflow analysis for Java programs. |
43 | * Liveness analysis checks that every statement is reachable. |
44 | * Exception analysis ensures that every checked exception that is |
45 | * thrown is declared or caught. Definite assignment analysis |
46 | * ensures that each variable is assigned when used. Definite |
47 | * unassignment analysis ensures that no final variable is assigned |
48 | * more than once. |
49 | * |
50 | * <p>The second edition of the JLS has a number of problems in the |
51 | * specification of these flow analysis problems. This implementation |
52 | * attempts to address those issues. |
53 | * |
54 | * <p>First, there is no accommodation for a finally clause that cannot |
55 | * complete normally. For liveness analysis, an intervening finally |
56 | * clause can cause a break, continue, or return not to reach its |
57 | * target. For exception analysis, an intervening finally clause can |
58 | * cause any exception to be "caught". For DA/DU analysis, the finally |
59 | * clause can prevent a transfer of control from propagating DA/DU |
60 | * state to the target. In addition, code in the finally clause can |
61 | * affect the DA/DU status of variables. |
62 | * |
63 | * <p>For try statements, we introduce the idea of a variable being |
64 | * definitely unassigned "everywhere" in a block. A variable V is |
65 | * "unassigned everywhere" in a block iff it is unassigned at the |
66 | * beginning of the block and there is no reachable assignment to V |
67 | * in the block. An assignment V=e is reachable iff V is not DA |
68 | * after e. Then we can say that V is DU at the beginning of the |
69 | * catch block iff V is DU everywhere in the try block. Similarly, V |
70 | * is DU at the beginning of the finally block iff V is DU everywhere |
71 | * in the try block and in every catch block. Specifically, the |
72 | * following bullet is added to 16.2.2 |
73 | * <pre> |
74 | * V is <em>unassigned everywhere</em> in a block if it is |
75 | * unassigned before the block and there is no reachable |
76 | * assignment to V within the block. |
77 | * </pre> |
78 | * <p>In 16.2.15, the third bullet (and all of its sub-bullets) for all |
79 | * try blocks is changed to |
80 | * <pre> |
81 | * V is definitely unassigned before a catch block iff V is |
82 | * definitely unassigned everywhere in the try block. |
83 | * </pre> |
84 | * <p>The last bullet (and all of its sub-bullets) for try blocks that |
85 | * have a finally block is changed to |
86 | * <pre> |
87 | * V is definitely unassigned before the finally block iff |
88 | * V is definitely unassigned everywhere in the try block |
89 | * and everywhere in each catch block of the try statement. |
90 | * </pre> |
91 | * <p>In addition, |
92 | * <pre> |
93 | * V is definitely assigned at the end of a constructor iff |
94 | * V is definitely assigned after the block that is the body |
95 | * of the constructor and V is definitely assigned at every |
96 | * return that can return from the constructor. |
97 | * </pre> |
98 | * <p>In addition, each continue statement with the loop as its target |
99 | * is treated as a jump to the end of the loop body, and "intervening" |
100 | * finally clauses are treated as follows: V is DA "due to the |
101 | * continue" iff V is DA before the continue statement or V is DA at |
102 | * the end of any intervening finally block. V is DU "due to the |
103 | * continue" iff any intervening finally cannot complete normally or V |
104 | * is DU at the end of every intervening finally block. This "due to |
105 | * the continue" concept is then used in the spec for the loops. |
106 | * |
107 | * <p>Similarly, break statements must consider intervening finally |
108 | * blocks. For liveness analysis, a break statement for which any |
109 | * intervening finally cannot complete normally is not considered to |
110 | * cause the target statement to be able to complete normally. Then |
111 | * we say V is DA "due to the break" iff V is DA before the break or |
112 | * V is DA at the end of any intervening finally block. V is DU "due |
113 | * to the break" iff any intervening finally cannot complete normally |
114 | * or V is DU at the break and at the end of every intervening |
115 | * finally block. (I suspect this latter condition can be |
116 | * simplified.) This "due to the break" is then used in the spec for |
117 | * all statements that can be "broken". |
118 | * |
119 | * <p>The return statement is treated similarly. V is DA "due to a |
120 | * return statement" iff V is DA before the return statement or V is |
121 | * DA at the end of any intervening finally block. Note that we |
122 | * don't have to worry about the return expression because this |
123 | * concept is only used for construcrors. |
124 | * |
125 | * <p>There is no spec in JLS2 for when a variable is definitely |
126 | * assigned at the end of a constructor, which is needed for final |
127 | * fields (8.3.1.2). We implement the rule that V is DA at the end |
128 | * of the constructor iff it is DA and the end of the body of the |
129 | * constructor and V is DA "due to" every return of the constructor. |
130 | * |
131 | * <p>Intervening finally blocks similarly affect exception analysis. An |
132 | * intervening finally that cannot complete normally allows us to ignore |
133 | * an otherwise uncaught exception. |
134 | * |
135 | * <p>To implement the semantics of intervening finally clauses, all |
136 | * nonlocal transfers (break, continue, return, throw, method call that |
137 | * can throw a checked exception, and a constructor invocation that can |
138 | * thrown a checked exception) are recorded in a queue, and removed |
139 | * from the queue when we complete processing the target of the |
140 | * nonlocal transfer. This allows us to modify the queue in accordance |
141 | * with the above rules when we encounter a finally clause. The only |
142 | * exception to this [no pun intended] is that checked exceptions that |
143 | * are known to be caught or declared to be caught in the enclosing |
144 | * method are not recorded in the queue, but instead are recorded in a |
145 | * global variable "Set<Type> thrown" that records the type of all |
146 | * exceptions that can be thrown. |
147 | * |
148 | * <p>Other minor issues the treatment of members of other classes |
149 | * (always considered DA except that within an anonymous class |
150 | * constructor, where DA status from the enclosing scope is |
151 | * preserved), treatment of the case expression (V is DA before the |
152 | * case expression iff V is DA after the switch expression), |
153 | * treatment of variables declared in a switch block (the implied |
154 | * DA/DU status after the switch expression is DU and not DA for |
155 | * variables defined in a switch block), the treatment of boolean ?: |
156 | * expressions (The JLS rules only handle b and c non-boolean; the |
157 | * new rule is that if b and c are boolean valued, then V is |
158 | * (un)assigned after a?b:c when true/false iff V is (un)assigned |
159 | * after b when true/false and V is (un)assigned after c when |
160 | * true/false). |
161 | * |
162 | * <p>There is the remaining question of what syntactic forms constitute a |
163 | * reference to a variable. It is conventional to allow this.x on the |
164 | * left-hand-side to initialize a final instance field named x, yet |
165 | * this.x isn't considered a "use" when appearing on a right-hand-side |
166 | * in most implementations. Should parentheses affect what is |
167 | * considered a variable reference? The simplest rule would be to |
168 | * allow unqualified forms only, parentheses optional, and phase out |
169 | * support for assigning to a final field via this.x. |
170 | * |
171 | * <p><b>This is NOT part of any API supported by Sun Microsystems. If |
172 | * you write code that depends on this, you do so at your own risk. |
173 | * This code and its internal interfaces are subject to change or |
174 | * deletion without notice.</b> |
175 | */ |
176 | public class Flow extends TreeScanner { |
177 | protected static final Context.Key<Flow> flowKey = |
178 | new Context.Key<Flow>(); |
179 | |
180 | private final Name.Table names; |
181 | private final Log log; |
182 | private final Symtab syms; |
183 | private final Types types; |
184 | private final Check chk; |
185 | private TreeMaker make; |
186 | private Lint lint; |
187 | |
188 | public static Flow instance(Context context) { |
189 | Flow instance = context.get(flowKey); |
190 | if (instance == null) |
191 | instance = new Flow(context); |
192 | return instance; |
193 | } |
194 | |
195 | protected Flow(Context context) { |
196 | context.put(flowKey, this); |
197 | |
198 | names = Name.Table.instance(context); |
199 | log = Log.instance(context); |
200 | syms = Symtab.instance(context); |
201 | types = Types.instance(context); |
202 | chk = Check.instance(context); |
203 | lint = Lint.instance(context); |
204 | } |
205 | |
206 | /** A flag that indicates whether the last statement could |
207 | * complete normally. |
208 | */ |
209 | private boolean alive; |
210 | |
211 | /** The set of definitely assigned variables. |
212 | */ |
213 | Bits inits; |
214 | |
215 | /** The set of definitely unassigned variables. |
216 | */ |
217 | Bits uninits; |
218 | |
219 | /** The set of variables that are definitely unassigned everywhere |
220 | * in current try block. This variable is maintained lazily; it is |
221 | * updated only when something gets removed from uninits, |
222 | * typically by being assigned in reachable code. To obtain the |
223 | * correct set of variables which are definitely unassigned |
224 | * anywhere in current try block, intersect uninitsTry and |
225 | * uninits. |
226 | */ |
227 | Bits uninitsTry; |
228 | |
229 | /** When analyzing a condition, inits and uninits are null. |
230 | * Instead we have: |
231 | */ |
232 | Bits initsWhenTrue; |
233 | Bits initsWhenFalse; |
234 | Bits uninitsWhenTrue; |
235 | Bits uninitsWhenFalse; |
236 | |
237 | /** A mapping from addresses to variable symbols. |
238 | */ |
239 | VarSymbol[] vars; |
240 | |
241 | /** The current class being defined. |
242 | */ |
243 | JCClassDecl classDef; |
244 | |
245 | /** The first variable sequence number in this class definition. |
246 | */ |
247 | int firstadr; |
248 | |
249 | /** The next available variable sequence number. |
250 | */ |
251 | int nextadr; |
252 | |
253 | /** The list of possibly thrown declarable exceptions. |
254 | */ |
255 | List<Type> thrown; |
256 | |
257 | /** The list of exceptions that are either caught or declared to be |
258 | * thrown. |
259 | */ |
260 | List<Type> caught; |
261 | |
262 | /** Set when processing a loop body the second time for DU analysis. */ |
263 | boolean loopPassTwo = false; |
264 | |
265 | /*-------------------- Environments ----------------------*/ |
266 | |
267 | /** A pending exit. These are the statements return, break, and |
268 | * continue. In addition, exception-throwing expressions or |
269 | * statements are put here when not known to be caught. This |
270 | * will typically result in an error unless it is within a |
271 | * try-finally whose finally block cannot complete normally. |
272 | */ |
273 | static class PendingExit { |
274 | JCTree tree; |
275 | Bits inits; |
276 | Bits uninits; |
277 | Type thrown; |
278 | PendingExit(JCTree tree, Bits inits, Bits uninits) { |
279 | this.tree = tree; |
280 | this.inits = inits.dup(); |
281 | this.uninits = uninits.dup(); |
282 | } |
283 | PendingExit(JCTree tree, Type thrown) { |
284 | this.tree = tree; |
285 | this.thrown = thrown; |
286 | } |
287 | } |
288 | |
289 | /** The currently pending exits that go from current inner blocks |
290 | * to an enclosing block, in source order. |
291 | */ |
292 | ListBuffer<PendingExit> pendingExits; |
293 | |
294 | /*-------------------- Exceptions ----------------------*/ |
295 | |
296 | /** Complain that pending exceptions are not caught. |
297 | */ |
298 | void errorUncaught() { |
299 | for (PendingExit exit = pendingExits.next(); |
300 | exit != null; |
301 | exit = pendingExits.next()) { |
302 | boolean synthetic = classDef != null && |
303 | classDef.pos == exit.tree.pos; |
304 | log.error(exit.tree.pos(), |
305 | synthetic |
306 | ? "unreported.exception.default.constructor" |
307 | : "unreported.exception.need.to.catch.or.throw", |
308 | exit.thrown); |
309 | } |
310 | } |
311 | |
312 | /** Record that exception is potentially thrown and check that it |
313 | * is caught. |
314 | */ |
315 | void markThrown(JCTree tree, Type exc) { |
316 | if (!chk.isUnchecked(tree.pos(), exc)) { |
317 | if (!chk.isHandled(exc, caught)) |
318 | pendingExits.append(new PendingExit(tree, exc)); |
319 | thrown = chk.incl(exc, thrown); |
320 | } |
321 | } |
322 | |
323 | /*-------------- Processing variables ----------------------*/ |
324 | |
325 | /** Do we need to track init/uninit state of this symbol? |
326 | * I.e. is symbol either a local or a blank final variable? |
327 | */ |
328 | boolean trackable(VarSymbol sym) { |
329 | return |
330 | (sym.owner.kind == MTH || |
331 | ((sym.flags() & (FINAL | HASINIT | PARAMETER)) == FINAL && |
332 | classDef.sym.isEnclosedBy((ClassSymbol)sym.owner))); |
333 | } |
334 | |
335 | /** Initialize new trackable variable by setting its address field |
336 | * to the next available sequence number and entering it under that |
337 | * index into the vars array. |
338 | */ |
339 | void newVar(VarSymbol sym) { |
340 | if (nextadr == vars.length) { |
341 | VarSymbol[] newvars = new VarSymbol[nextadr * 2]; |
342 | System.arraycopy(vars, 0, newvars, 0, nextadr); |
343 | vars = newvars; |
344 | } |
345 | sym.adr = nextadr; |
346 | vars[nextadr] = sym; |
347 | inits.excl(nextadr); |
348 | uninits.incl(nextadr); |
349 | nextadr++; |
350 | } |
351 | |
352 | /** Record an initialization of a trackable variable. |
353 | */ |
354 | void letInit(DiagnosticPosition pos, VarSymbol sym) { |
355 | if (sym.adr >= firstadr && trackable(sym)) { |
356 | if ((sym.flags() & FINAL) != 0) { |
357 | if ((sym.flags() & PARAMETER) != 0) { |
358 | log.error(pos, "final.parameter.may.not.be.assigned", |
359 | sym); |
360 | } else if (!uninits.isMember(sym.adr)) { |
361 | log.error(pos, |
362 | loopPassTwo |
363 | ? "var.might.be.assigned.in.loop" |
364 | : "var.might.already.be.assigned", |
365 | sym); |
366 | } else if (!inits.isMember(sym.adr)) { |
367 | // reachable assignment |
368 | uninits.excl(sym.adr); |
369 | uninitsTry.excl(sym.adr); |
370 | } else { |
371 | //log.rawWarning(pos, "unreachable assignment");//DEBUG |
372 | uninits.excl(sym.adr); |
373 | } |
374 | } |
375 | inits.incl(sym.adr); |
376 | } else if ((sym.flags() & FINAL) != 0) { |
377 | log.error(pos, "var.might.already.be.assigned", sym); |
378 | } |
379 | } |
380 | |
381 | /** If tree is either a simple name or of the form this.name or |
382 | * C.this.name, and tree represents a trackable variable, |
383 | * record an initialization of the variable. |
384 | */ |
385 | void letInit(JCTree tree) { |
386 | tree = TreeInfo.skipParens(tree); |
387 | if (tree.getTag() == JCTree.IDENT || tree.getTag() == JCTree.SELECT) { |
388 | Symbol sym = TreeInfo.symbol(tree); |
389 | letInit(tree.pos(), (VarSymbol)sym); |
390 | } |
391 | } |
392 | |
393 | /** Check that trackable variable is initialized. |
394 | */ |
395 | void checkInit(DiagnosticPosition pos, VarSymbol sym) { |
396 | if ((sym.adr >= firstadr || sym.owner.kind != TYP) && |
397 | trackable(sym) && |
398 | !inits.isMember(sym.adr)) { |
399 | log.error(pos, "var.might.not.have.been.initialized", |
400 | sym); |
401 | inits.incl(sym.adr); |
402 | } |
403 | } |
404 | |
405 | /*-------------------- Handling jumps ----------------------*/ |
406 | |
407 | /** Record an outward transfer of control. */ |
408 | void recordExit(JCTree tree) { |
409 | pendingExits.append(new PendingExit(tree, inits, uninits)); |
410 | markDead(); |
411 | } |
412 | |
413 | /** Resolve all breaks of this statement. */ |
414 | boolean resolveBreaks(JCTree tree, |
415 | ListBuffer<PendingExit> oldPendingExits) { |
416 | boolean result = false; |
417 | List<PendingExit> exits = pendingExits.toList(); |
418 | pendingExits = oldPendingExits; |
419 | for (; exits.nonEmpty(); exits = exits.tail) { |
420 | PendingExit exit = exits.head; |
421 | if (exit.tree.getTag() == JCTree.BREAK && |
422 | ((JCBreak) exit.tree).target == tree) { |
423 | inits.andSet(exit.inits); |
424 | uninits.andSet(exit.uninits); |
425 | result = true; |
426 | } else { |
427 | pendingExits.append(exit); |
428 | } |
429 | } |
430 | return result; |
431 | } |
432 | |
433 | /** Resolve all continues of this statement. */ |
434 | boolean resolveContinues(JCTree tree) { |
435 | boolean result = false; |
436 | List<PendingExit> exits = pendingExits.toList(); |
437 | pendingExits = new ListBuffer<PendingExit>(); |
438 | for (; exits.nonEmpty(); exits = exits.tail) { |
439 | PendingExit exit = exits.head; |
440 | if (exit.tree.getTag() == JCTree.CONTINUE && |
441 | ((JCContinue) exit.tree).target == tree) { |
442 | inits.andSet(exit.inits); |
443 | uninits.andSet(exit.uninits); |
444 | result = true; |
445 | } else { |
446 | pendingExits.append(exit); |
447 | } |
448 | } |
449 | return result; |
450 | } |
451 | |
452 | /** Record that statement is unreachable. |
453 | */ |
454 | void markDead() { |
455 | inits.inclRange(firstadr, nextadr); |
456 | uninits.inclRange(firstadr, nextadr); |
457 | alive = false; |
458 | } |
459 | |
460 | /** Split (duplicate) inits/uninits into WhenTrue/WhenFalse sets |
461 | */ |
462 | void split() { |
463 | initsWhenFalse = inits.dup(); |
464 | uninitsWhenFalse = uninits.dup(); |
465 | initsWhenTrue = inits; |
466 | uninitsWhenTrue = uninits; |
467 | inits = uninits = null; |
468 | } |
469 | |
470 | /** Merge (intersect) inits/uninits from WhenTrue/WhenFalse sets. |
471 | */ |
472 | void merge() { |
473 | inits = initsWhenFalse.andSet(initsWhenTrue); |
474 | uninits = uninitsWhenFalse.andSet(uninitsWhenTrue); |
475 | } |
476 | |
477 | /* ************************************************************************ |
478 | * Visitor methods for statements and definitions |
479 | *************************************************************************/ |
480 | |
481 | /** Analyze a definition. |
482 | */ |
483 | void scanDef(JCTree tree) { |
484 | scanStat(tree); |
485 | if (tree != null && tree.getTag() == JCTree.BLOCK && !alive) { |
486 | log.error(tree.pos(), |
487 | "initializer.must.be.able.to.complete.normally"); |
488 | } |
489 | } |
490 | |
491 | /** Analyze a statement. Check that statement is reachable. |
492 | */ |
493 | void scanStat(JCTree tree) { |
494 | if (!alive && tree != null) { |
495 | log.error(tree.pos(), "unreachable.stmt"); |
496 | if (tree.getTag() != JCTree.SKIP) alive = true; |
497 | } |
498 | scan(tree); |
499 | } |
500 | |
501 | /** Analyze list of statements. |
502 | */ |
503 | void scanStats(List<? extends JCStatement> trees) { |
504 | if (trees != null) |
505 | for (List<? extends JCStatement> l = trees; l.nonEmpty(); l = l.tail) |
506 | scanStat(l.head); |
507 | } |
508 | |
509 | /** Analyze an expression. Make sure to set (un)inits rather than |
510 | * (un)initsWhenTrue(WhenFalse) on exit. |
511 | */ |
512 | void scanExpr(JCTree tree) { |
513 | if (tree != null) { |
514 | scan(tree); |
515 | if (inits == null) merge(); |
516 | } |
517 | } |
518 | |
519 | /** Analyze a list of expressions. |
520 | */ |
521 | void scanExprs(List<? extends JCExpression> trees) { |
522 | if (trees != null) |
523 | for (List<? extends JCExpression> l = trees; l.nonEmpty(); l = l.tail) |
524 | scanExpr(l.head); |
525 | } |
526 | |
527 | /** Analyze a condition. Make sure to set (un)initsWhenTrue(WhenFalse) |
528 | * rather than (un)inits on exit. |
529 | */ |
530 | void scanCond(JCTree tree) { |
531 | if (tree.type.isFalse()) { |
532 | if (inits == null) merge(); |
533 | initsWhenTrue = inits.dup(); |
534 | initsWhenTrue.inclRange(firstadr, nextadr); |
535 | uninitsWhenTrue = uninits.dup(); |
536 | uninitsWhenTrue.inclRange(firstadr, nextadr); |
537 | initsWhenFalse = inits; |
538 | uninitsWhenFalse = uninits; |
539 | } else if (tree.type.isTrue()) { |
540 | if (inits == null) merge(); |
541 | initsWhenFalse = inits.dup(); |
542 | initsWhenFalse.inclRange(firstadr, nextadr); |
543 | uninitsWhenFalse = uninits.dup(); |
544 | uninitsWhenFalse.inclRange(firstadr, nextadr); |
545 | initsWhenTrue = inits; |
546 | uninitsWhenTrue = uninits; |
547 | } else { |
548 | scan(tree); |
549 | if (inits != null) split(); |
550 | } |
551 | inits = uninits = null; |
552 | } |
553 | |
554 | /* ------------ Visitor methods for various sorts of trees -------------*/ |
555 | |
556 | public void visitClassDef(JCClassDecl tree) { |
557 | if (tree.sym == null) return; |
558 | |
559 | JCClassDecl classDefPrev = classDef; |
560 | List<Type> thrownPrev = thrown; |
561 | List<Type> caughtPrev = caught; |
562 | boolean alivePrev = alive; |
563 | int firstadrPrev = firstadr; |
564 | int nextadrPrev = nextadr; |
565 | ListBuffer<PendingExit> pendingExitsPrev = pendingExits; |
566 | Lint lintPrev = lint; |
567 | |
568 | pendingExits = new ListBuffer<PendingExit>(); |
569 | if (tree.name != names.empty) { |
570 | caught = List.nil(); |
571 | firstadr = nextadr; |
572 | } |
573 | classDef = tree; |
574 | thrown = List.nil(); |
575 | lint = lint.augment(tree.sym.attributes_field); |
576 | |
577 | try { |
578 | // define all the static fields |
579 | for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) { |
580 | if (l.head.getTag() == JCTree.VARDEF) { |
581 | JCVariableDecl def = (JCVariableDecl)l.head; |
582 | if ((def.mods.flags & STATIC) != 0) { |
583 | VarSymbol sym = def.sym; |
584 | if (trackable(sym)) |
585 | newVar(sym); |
586 | } |
587 | } |
588 | } |
589 | |
590 | // process all the static initializers |
591 | for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) { |
592 | if (l.head.getTag() != JCTree.METHODDEF && |
593 | (TreeInfo.flags(l.head) & STATIC) != 0) { |
594 | scanDef(l.head); |
595 | errorUncaught(); |
596 | } |
597 | } |
598 | |
599 | // add intersection of all thrown clauses of initial constructors |
600 | // to set of caught exceptions, unless class is anonymous. |
601 | if (tree.name != names.empty) { |
602 | boolean firstConstructor = true; |
603 | for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) { |
604 | if (TreeInfo.isInitialConstructor(l.head)) { |
605 | List<Type> mthrown = |
606 | ((JCMethodDecl) l.head).sym.type.getThrownTypes(); |
607 | if (firstConstructor) { |
608 | caught = mthrown; |
609 | firstConstructor = false; |
610 | } else { |
611 | caught = chk.intersect(mthrown, caught); |
612 | } |
613 | } |
614 | } |
615 | } |
616 | |
617 | // define all the instance fields |
618 | for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) { |
619 | if (l.head.getTag() == JCTree.VARDEF) { |
620 | JCVariableDecl def = (JCVariableDecl)l.head; |
621 | if ((def.mods.flags & STATIC) == 0) { |
622 | VarSymbol sym = def.sym; |
623 | if (trackable(sym)) |
624 | newVar(sym); |
625 | } |
626 | } |
627 | } |
628 | |
629 | // process all the instance initializers |
630 | for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) { |
631 | if (l.head.getTag() != JCTree.METHODDEF && |
632 | (TreeInfo.flags(l.head) & STATIC) == 0) { |
633 | scanDef(l.head); |
634 | errorUncaught(); |
635 | } |
636 | } |
637 | |
638 | // in an anonymous class, add the set of thrown exceptions to |
639 | // the throws clause of the synthetic constructor and propagate |
640 | // outwards. |
641 | if (tree.name == names.empty) { |
642 | for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) { |
643 | if (TreeInfo.isInitialConstructor(l.head)) { |
644 | JCMethodDecl mdef = (JCMethodDecl)l.head; |
645 | mdef.thrown = make.Types(thrown); |
646 | mdef.sym.type.setThrown(thrown); |
647 | } |
648 | } |
649 | thrownPrev = chk.union(thrown, thrownPrev); |
650 | } |
651 | |
652 | // process all the methods |
653 | for (List<JCTree> l = tree.defs; l.nonEmpty(); l = l.tail) { |
654 | if (l.head.getTag() == JCTree.METHODDEF) { |
655 | scan(l.head); |
656 | errorUncaught(); |
657 | } |
658 | } |
659 | |
660 | thrown = thrownPrev; |
661 | } finally { |
662 | pendingExits = pendingExitsPrev; |
663 | alive = alivePrev; |
664 | nextadr = nextadrPrev; |
665 | firstadr = firstadrPrev; |
666 | caught = caughtPrev; |
667 | classDef = classDefPrev; |
668 | lint = lintPrev; |
669 | } |
670 | } |
671 | |
672 | public void visitMethodDef(JCMethodDecl tree) { |
673 | if (tree.body == null) return; |
674 | |
675 | List<Type> caughtPrev = caught; |
676 | List<Type> mthrown = tree.sym.type.getThrownTypes(); |
677 | Bits initsPrev = inits.dup(); |
678 | Bits uninitsPrev = uninits.dup(); |
679 | int nextadrPrev = nextadr; |
680 | int firstadrPrev = firstadr; |
681 | Lint lintPrev = lint; |
682 | |
683 | lint = lint.augment(tree.sym.attributes_field); |
684 | |
685 | assert pendingExits.isEmpty(); |
686 | |
687 | try { |
688 | boolean isInitialConstructor = |
689 | TreeInfo.isInitialConstructor(tree); |
690 | |
691 | if (!isInitialConstructor) |
692 | firstadr = nextadr; |
693 | for (List<JCVariableDecl> l = tree.params; l.nonEmpty(); l = l.tail) { |
694 | JCVariableDecl def = l.head; |
695 | scan(def); |
696 | inits.incl(def.sym.adr); |
697 | uninits.excl(def.sym.adr); |
698 | } |
699 | if (isInitialConstructor) |
700 | caught = chk.union(caught, mthrown); |
701 | else if ((tree.sym.flags() & (BLOCK | STATIC)) != BLOCK) |
702 | caught = mthrown; |
703 | // else we are in an instance initializer block; |
704 | // leave caught unchanged. |
705 | |
706 | alive = true; |
707 | scanStat(tree.body); |
708 | |
709 | if (alive && tree.sym.type.getReturnType().tag != VOID) |
710 | log.error(TreeInfo.diagEndPos(tree.body), "missing.ret.stmt"); |
711 | |
712 | if (isInitialConstructor) { |
713 | for (int i = firstadr; i < nextadr; i++) |
714 | if (vars[i].owner == classDef.sym) |
715 | checkInit(TreeInfo.diagEndPos(tree.body), vars[i]); |
716 | } |
717 | List<PendingExit> exits = pendingExits.toList(); |
718 | pendingExits = new ListBuffer<PendingExit>(); |
719 | while (exits.nonEmpty()) { |
720 | PendingExit exit = exits.head; |
721 | exits = exits.tail; |
722 | if (exit.thrown == null) { |
723 | assert exit.tree.getTag() == JCTree.RETURN; |
724 | if (isInitialConstructor) { |
725 | inits = exit.inits; |
726 | for (int i = firstadr; i < nextadr; i++) |
727 | checkInit(exit.tree.pos(), vars[i]); |
728 | } |
729 | } else { |
730 | // uncaught throws will be reported later |
731 | pendingExits.append(exit); |
732 | } |
733 | } |
734 | } finally { |
735 | inits = initsPrev; |
736 | uninits = uninitsPrev; |
737 | nextadr = nextadrPrev; |
738 | firstadr = firstadrPrev; |
739 | caught = caughtPrev; |
740 | lint = lintPrev; |
741 | } |
742 | } |
743 | |
744 | public void visitVarDef(JCVariableDecl tree) { |
745 | boolean track = trackable(tree.sym); |
746 | if (track && tree.sym.owner.kind == MTH) newVar(tree.sym); |
747 | if (tree.init != null) { |
748 | Lint lintPrev = lint; |
749 | lint = lint.augment(tree.sym.attributes_field); |
750 | try{ |
751 | scanExpr(tree.init); |
752 | if (track) letInit(tree.pos(), tree.sym); |
753 | } finally { |
754 | lint = lintPrev; |
755 | } |
756 | } |
757 | } |
758 | |
759 | public void visitBlock(JCBlock tree) { |
760 | int nextadrPrev = nextadr; |
761 | scanStats(tree.stats); |
762 | nextadr = nextadrPrev; |
763 | } |
764 | |
765 | public void visitDoLoop(JCDoWhileLoop tree) { |
766 | ListBuffer<PendingExit> prevPendingExits = pendingExits; |
767 | boolean prevLoopPassTwo = loopPassTwo; |
768 | pendingExits = new ListBuffer<PendingExit>(); |
769 | do { |
770 | Bits uninitsEntry = uninits.dup(); |
771 | scanStat(tree.body); |
772 | alive |= resolveContinues(tree); |
773 | scanCond(tree.cond); |
774 | if (log.nerrors != 0 || |
775 | loopPassTwo || |
776 | uninitsEntry.diffSet(uninitsWhenTrue).nextBit(firstadr)==-1) |
777 | break; |
778 | inits = initsWhenTrue; |
779 | uninits = uninitsEntry.andSet(uninitsWhenTrue); |
780 | loopPassTwo = true; |
781 | alive = true; |
782 | } while (true); |
783 | loopPassTwo = prevLoopPassTwo; |
784 | inits = initsWhenFalse; |
785 | uninits = uninitsWhenFalse; |
786 | alive = alive && !tree.cond.type.isTrue(); |
787 | alive |= resolveBreaks(tree, prevPendingExits); |
788 | } |
789 | |
790 | public void visitWhileLoop(JCWhileLoop tree) { |
791 | ListBuffer<PendingExit> prevPendingExits = pendingExits; |
792 | boolean prevLoopPassTwo = loopPassTwo; |
793 | Bits initsCond; |
794 | Bits uninitsCond; |
795 | pendingExits = new ListBuffer<PendingExit>(); |
796 | do { |
797 | Bits uninitsEntry = uninits.dup(); |
798 | scanCond(tree.cond); |
799 | initsCond = initsWhenFalse; |
800 | uninitsCond = uninitsWhenFalse; |
801 | inits = initsWhenTrue; |
802 | uninits = uninitsWhenTrue; |
803 | alive = !tree.cond.type.isFalse(); |
804 | scanStat(tree.body); |
805 | alive |= resolveContinues(tree); |
806 | if (log.nerrors != 0 || |
807 | loopPassTwo || |
808 | uninitsEntry.diffSet(uninits).nextBit(firstadr) == -1) |
809 | break; |
810 | uninits = uninitsEntry.andSet(uninits); |
811 | loopPassTwo = true; |
812 | alive = true; |
813 | } while (true); |
814 | loopPassTwo = prevLoopPassTwo; |
815 | inits = initsCond; |
816 | uninits = uninitsCond; |
817 | alive = resolveBreaks(tree, prevPendingExits) || |
818 | !tree.cond.type.isTrue(); |
819 | } |
820 | |
821 | public void visitForLoop(JCForLoop tree) { |
822 | ListBuffer<PendingExit> prevPendingExits = pendingExits; |
823 | boolean prevLoopPassTwo = loopPassTwo; |
824 | int nextadrPrev = nextadr; |
825 | scanStats(tree.init); |
826 | Bits initsCond; |
827 | Bits uninitsCond; |
828 | pendingExits = new ListBuffer<PendingExit>(); |
829 | do { |
830 | Bits uninitsEntry = uninits.dup(); |
831 | if (tree.cond != null) { |
832 | scanCond(tree.cond); |
833 | initsCond = initsWhenFalse; |
834 | uninitsCond = uninitsWhenFalse; |
835 | inits = initsWhenTrue; |
836 | uninits = uninitsWhenTrue; |
837 | alive = !tree.cond.type.isFalse(); |
838 | } else { |
839 | initsCond = inits.dup(); |
840 | initsCond.inclRange(firstadr, nextadr); |
841 | uninitsCond = uninits.dup(); |
842 | uninitsCond.inclRange(firstadr, nextadr); |
843 | alive = true; |
844 | } |
845 | scanStat(tree.body); |
846 | alive |= resolveContinues(tree); |
847 | scan(tree.step); |
848 | if (log.nerrors != 0 || |
849 | loopPassTwo || |
850 | uninitsEntry.dup().diffSet(uninits).nextBit(firstadr) == -1) |
851 | break; |
852 | uninits = uninitsEntry.andSet(uninits); |
853 | loopPassTwo = true; |
854 | alive = true; |
855 | } while (true); |
856 | loopPassTwo = prevLoopPassTwo; |
857 | inits = initsCond; |
858 | uninits = uninitsCond; |
859 | alive = resolveBreaks(tree, prevPendingExits) || |
860 | tree.cond != null && !tree.cond.type.isTrue(); |
861 | nextadr = nextadrPrev; |
862 | } |
863 | |
864 | public void visitForeachLoop(JCEnhancedForLoop tree) { |
865 | visitVarDef(tree.var); |
866 | |
867 | ListBuffer<PendingExit> prevPendingExits = pendingExits; |
868 | boolean prevLoopPassTwo = loopPassTwo; |
869 | int nextadrPrev = nextadr; |
870 | scan(tree.expr); |
871 | Bits initsStart = inits.dup(); |
872 | Bits uninitsStart = uninits.dup(); |
873 | |
874 | letInit(tree.pos(), tree.var.sym); |
875 | pendingExits = new ListBuffer<PendingExit>(); |
876 | do { |
877 | Bits uninitsEntry = uninits.dup(); |
878 | scanStat(tree.body); |
879 | alive |= resolveContinues(tree); |
880 | if (log.nerrors != 0 || |
881 | loopPassTwo || |
882 | uninitsEntry.diffSet(uninits).nextBit(firstadr) == -1) |
883 | break; |
884 | uninits = uninitsEntry.andSet(uninits); |
885 | loopPassTwo = true; |
886 | alive = true; |
887 | } while (true); |
888 | loopPassTwo = prevLoopPassTwo; |
889 | inits = initsStart; |
890 | uninits = uninitsStart.andSet(uninits); |
891 | resolveBreaks(tree, prevPendingExits); |
892 | alive = true; |
893 | nextadr = nextadrPrev; |
894 | } |
895 | |
896 | public void visitLabelled(JCLabeledStatement tree) { |
897 | ListBuffer<PendingExit> prevPendingExits = pendingExits; |
898 | pendingExits = new ListBuffer<PendingExit>(); |
899 | scanStat(tree.body); |
900 | alive |= resolveBreaks(tree, prevPendingExits); |
901 | } |
902 | |
903 | public void visitSwitch(JCSwitch tree) { |
904 | ListBuffer<PendingExit> prevPendingExits = pendingExits; |
905 | pendingExits = new ListBuffer<PendingExit>(); |
906 | int nextadrPrev = nextadr; |
907 | scanExpr(tree.selector); |
908 | Bits initsSwitch = inits; |
909 | Bits uninitsSwitch = uninits.dup(); |
910 | boolean hasDefault = false; |
911 | for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) { |
912 | alive = true; |
913 | inits = initsSwitch.dup(); |
914 | uninits = uninits.andSet(uninitsSwitch); |
915 | JCCase c = l.head; |
916 | if (c.pat == null) |
917 | hasDefault = true; |
918 | else |
919 | scanExpr(c.pat); |
920 | scanStats(c.stats); |
921 | addVars(c.stats, initsSwitch, uninitsSwitch); |
922 | // Warn about fall-through if lint switch fallthrough enabled. |
923 | if (!loopPassTwo && |
924 | alive && |
925 | lint.isEnabled(Lint.LintCategory.FALLTHROUGH) && |
926 | c.stats.nonEmpty() && l.tail.nonEmpty()) |
927 | log.warning(l.tail.head.pos(), |
928 | "possible.fall-through.into.case"); |
929 | } |
930 | if (!hasDefault) { |
931 | inits.andSet(initsSwitch); |
932 | alive = true; |
933 | } |
934 | alive |= resolveBreaks(tree, prevPendingExits); |
935 | nextadr = nextadrPrev; |
936 | } |
937 | // where |
938 | /** Add any variables defined in stats to inits and uninits. */ |
939 | private static void addVars(List<JCStatement> stats, Bits inits, |
940 | Bits uninits) { |
941 | for (;stats.nonEmpty(); stats = stats.tail) { |
942 | JCTree stat = stats.head; |
943 | if (stat.getTag() == JCTree.VARDEF) { |
944 | int adr = ((JCVariableDecl) stat).sym.adr; |
945 | inits.excl(adr); |
946 | uninits.incl(adr); |
947 | } |
948 | } |
949 | } |
950 | |
951 | public void visitTry(JCTry tree) { |
952 | List<Type> caughtPrev = caught; |
953 | List<Type> thrownPrev = thrown; |
954 | thrown = List.nil(); |
955 | for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) |
956 | caught = chk.incl(l.head.param.type, caught); |
957 | Bits uninitsTryPrev = uninitsTry; |
958 | ListBuffer<PendingExit> prevPendingExits = pendingExits; |
959 | pendingExits = new ListBuffer<PendingExit>(); |
960 | Bits initsTry = inits.dup(); |
961 | uninitsTry = uninits.dup(); |
962 | scanStat(tree.body); |
963 | List<Type> thrownInTry = thrown; |
964 | thrown = thrownPrev; |
965 | caught = caughtPrev; |
966 | boolean aliveEnd = alive; |
967 | uninitsTry.andSet(uninits); |
968 | Bits initsEnd = inits; |
969 | Bits uninitsEnd = uninits; |
970 | int nextadrCatch = nextadr; |
971 | |
972 | List<Type> caughtInTry = List.nil(); |
973 | for (List<JCCatch> l = tree.catchers; l.nonEmpty(); l = l.tail) { |
974 | alive = true; |
975 | JCVariableDecl param = l.head.param; |
976 | Type exc = param.type; |
977 | if (chk.subset(exc, caughtInTry)) { |
978 | log.error(l.head.pos(), |
979 | "except.already.caught", exc); |
980 | } else if (!chk.isUnchecked(l.head.pos(), exc) && |
981 | exc.tsym != syms.throwableType.tsym && |
982 | exc.tsym != syms.exceptionType.tsym && |
983 | !chk.intersects(exc, thrownInTry)) { |
984 | log.error(l.head.pos(), |
985 | "except.never.thrown.in.try", exc); |
986 | } |
987 | caughtInTry = chk.incl(exc, caughtInTry); |
988 | inits = initsTry.dup(); |
989 | uninits = uninitsTry.dup(); |
990 | scan(param); |
991 | inits.incl(param.sym.adr); |
992 | uninits.excl(param.sym.adr); |
993 | scanStat(l.head.body); |
994 | initsEnd.andSet(inits); |
995 | uninitsEnd.andSet(uninits); |
996 | nextadr = nextadrCatch; |
997 | aliveEnd |= alive; |
998 | } |
999 | if (tree.finalizer != null) { |
1000 | List<Type> savedThrown = thrown; |
1001 | thrown = List.nil(); |
1002 | inits = initsTry.dup(); |
1003 | uninits = uninitsTry.dup(); |
1004 | ListBuffer<PendingExit> exits = pendingExits; |
1005 | pendingExits = prevPendingExits; |
1006 | alive = true; |
1007 | scanStat(tree.finalizer); |
1008 | if (!alive) { |
1009 | // discard exits and exceptions from try and finally |
1010 | thrown = chk.union(thrown, thrownPrev); |
1011 | if (!loopPassTwo && |
1012 | lint.isEnabled(Lint.LintCategory.FINALLY)) { |
1013 | log.warning(TreeInfo.diagEndPos(tree.finalizer), |
1014 | "finally.cannot.complete"); |
1015 | } |
1016 | } else { |
1017 | thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry)); |
1018 | thrown = chk.union(thrown, savedThrown); |
1019 | uninits.andSet(uninitsEnd); |
1020 | // FIX: this doesn't preserve source order of exits in catch |
1021 | // versus finally! |
1022 | while (exits.nonEmpty()) { |
1023 | PendingExit exit = exits.next(); |
1024 | if (exit.inits != null) { |
1025 | exit.inits.orSet(inits); |
1026 | exit.uninits.andSet(uninits); |
1027 | } |
1028 | pendingExits.append(exit); |
1029 | } |
1030 | inits.orSet(initsEnd); |
1031 | alive = aliveEnd; |
1032 | } |
1033 | } else { |
1034 | thrown = chk.union(thrown, chk.diff(thrownInTry, caughtInTry)); |
1035 | inits = initsEnd; |
1036 | uninits = uninitsEnd; |
1037 | alive = aliveEnd; |
1038 | ListBuffer<PendingExit> exits = pendingExits; |
1039 | pendingExits = prevPendingExits; |
1040 | while (exits.nonEmpty()) pendingExits.append(exits.next()); |
1041 | } |
1042 | uninitsTry.andSet(uninitsTryPrev).andSet(uninits); |
1043 | } |
1044 | |
1045 | public void visitConditional(JCConditional tree) { |
1046 | scanCond(tree.cond); |
1047 | Bits initsBeforeElse = initsWhenFalse; |
1048 | Bits uninitsBeforeElse = uninitsWhenFalse; |
1049 | inits = initsWhenTrue; |
1050 | uninits = uninitsWhenTrue; |
1051 | if (tree.truepart.type.tag == BOOLEAN && |
1052 | tree.falsepart.type.tag == BOOLEAN) { |
1053 | // if b and c are boolean valued, then |
1054 | // v is (un)assigned after a?b:c when true iff |
1055 | // v is (un)assigned after b when true and |
1056 | // v is (un)assigned after c when true |
1057 | scanCond(tree.truepart); |
1058 | Bits initsAfterThenWhenTrue = initsWhenTrue.dup(); |
1059 | Bits initsAfterThenWhenFalse = initsWhenFalse.dup(); |
1060 | Bits uninitsAfterThenWhenTrue = uninitsWhenTrue.dup(); |
1061 | Bits uninitsAfterThenWhenFalse = uninitsWhenFalse.dup(); |
1062 | inits = initsBeforeElse; |
1063 | uninits = uninitsBeforeElse; |
1064 | scanCond(tree.falsepart); |
1065 | initsWhenTrue.andSet(initsAfterThenWhenTrue); |
1066 | initsWhenFalse.andSet(initsAfterThenWhenFalse); |
1067 | uninitsWhenTrue.andSet(uninitsAfterThenWhenTrue); |
1068 | uninitsWhenFalse.andSet(uninitsAfterThenWhenFalse); |
1069 | } else { |
1070 | scanExpr(tree.truepart); |
1071 | Bits initsAfterThen = inits.dup(); |
1072 | Bits uninitsAfterThen = uninits.dup(); |
1073 | inits = initsBeforeElse; |
1074 | uninits = uninitsBeforeElse; |
1075 | scanExpr(tree.falsepart); |
1076 | inits.andSet(initsAfterThen); |
1077 | uninits.andSet(uninitsAfterThen); |
1078 | } |
1079 | } |
1080 | |
1081 | public void visitIf(JCIf tree) { |
1082 | scanCond(tree.cond); |
1083 | Bits initsBeforeElse = initsWhenFalse; |
1084 | Bits uninitsBeforeElse = uninitsWhenFalse; |
1085 | inits = initsWhenTrue; |
1086 | uninits = uninitsWhenTrue; |
1087 | scanStat(tree.thenpart); |
1088 | if (tree.elsepart != null) { |
1089 | boolean aliveAfterThen = alive; |
1090 | alive = true; |
1091 | Bits initsAfterThen = inits.dup(); |
1092 | Bits uninitsAfterThen = uninits.dup(); |
1093 | inits = initsBeforeElse; |
1094 | uninits = uninitsBeforeElse; |
1095 | scanStat(tree.elsepart); |
1096 | inits.andSet(initsAfterThen); |
1097 | uninits.andSet(uninitsAfterThen); |
1098 | alive = alive | aliveAfterThen; |
1099 | } else { |
1100 | inits.andSet(initsBeforeElse); |
1101 | uninits.andSet(uninitsBeforeElse); |
1102 | alive = true; |
1103 | } |
1104 | } |
1105 | |
1106 | |
1107 | |
1108 | public void visitBreak(JCBreak tree) { |
1109 | recordExit(tree); |
1110 | } |
1111 | |
1112 | public void visitContinue(JCContinue tree) { |
1113 | recordExit(tree); |
1114 | } |
1115 | |
1116 | public void visitReturn(JCReturn tree) { |
1117 | scanExpr(tree.expr); |
1118 | // if not initial constructor, should markDead instead of recordExit |
1119 | recordExit(tree); |
1120 | } |
1121 | |
1122 | public void visitThrow(JCThrow tree) { |
1123 | scanExpr(tree.expr); |
1124 | markThrown(tree, tree.expr.type); |
1125 | markDead(); |
1126 | } |
1127 | |
1128 | public void visitApply(JCMethodInvocation tree) { |
1129 | scanExpr(tree.meth); |
1130 | scanExprs(tree.args); |
1131 | for (List<Type> l = tree.meth.type.getThrownTypes(); l.nonEmpty(); l = l.tail) |
1132 | markThrown(tree, l.head); |
1133 | } |
1134 | |
1135 | public void visitNewClass(JCNewClass tree) { |
1136 | scanExpr(tree.encl); |
1137 | scanExprs(tree.args); |
1138 | // scan(tree.def); |
1139 | for (List<Type> l = tree.constructor.type.getThrownTypes(); |
1140 | l.nonEmpty(); |
1141 | l = l.tail) |
1142 | markThrown(tree, l.head); |
1143 | scan(tree.def); |
1144 | } |
1145 | |
1146 | public void visitNewArray(JCNewArray tree) { |
1147 | scanExprs(tree.dims); |
1148 | scanExprs(tree.elems); |
1149 | } |
1150 | |
1151 | public void visitAssert(JCAssert tree) { |
1152 | Bits initsExit = inits.dup(); |
1153 | Bits uninitsExit = uninits.dup(); |
1154 | scanCond(tree.cond); |
1155 | uninitsExit.andSet(uninitsWhenTrue); |
1156 | if (tree.detail != null) { |
1157 | inits = initsWhenFalse; |
1158 | uninits = uninitsWhenFalse; |
1159 | scanExpr(tree.detail); |
1160 | } |
1161 | inits = initsExit; |
1162 | uninits = uninitsExit; |
1163 | } |
1164 | |
1165 | public void visitAssign(JCAssign tree) { |
1166 | JCTree lhs = TreeInfo.skipParens(tree.lhs); |
1167 | if (!(lhs instanceof JCIdent)) scanExpr(lhs); |
1168 | scanExpr(tree.rhs); |
1169 | letInit(lhs); |
1170 | } |
1171 | |
1172 | public void visitAssignop(JCAssignOp tree) { |
1173 | scanExpr(tree.lhs); |
1174 | scanExpr(tree.rhs); |
1175 | letInit(tree.lhs); |
1176 | } |
1177 | |
1178 | public void visitUnary(JCUnary tree) { |
1179 | switch (tree.getTag()) { |
1180 | case JCTree.NOT: |
1181 | scanCond(tree.arg); |
1182 | Bits t = initsWhenFalse; |
1183 | initsWhenFalse = initsWhenTrue; |
1184 | initsWhenTrue = t; |
1185 | t = uninitsWhenFalse; |
1186 | uninitsWhenFalse = uninitsWhenTrue; |
1187 | uninitsWhenTrue = t; |
1188 | break; |
1189 | case JCTree.PREINC: case JCTree.POSTINC: |
1190 | case JCTree.PREDEC: case JCTree.POSTDEC: |
1191 | scanExpr(tree.arg); |
1192 | letInit(tree.arg); |
1193 | break; |
1194 | default: |
1195 | scanExpr(tree.arg); |
1196 | } |
1197 | } |
1198 | |
1199 | public void visitBinary(JCBinary tree) { |
1200 | switch (tree.getTag()) { |
1201 | case JCTree.AND: |
1202 | scanCond(tree.lhs); |
1203 | Bits initsWhenFalseLeft = initsWhenFalse; |
1204 | Bits uninitsWhenFalseLeft = uninitsWhenFalse; |
1205 | inits = initsWhenTrue; |
1206 | uninits = uninitsWhenTrue; |
1207 | scanCond(tree.rhs); |
1208 | initsWhenFalse.andSet(initsWhenFalseLeft); |
1209 | uninitsWhenFalse.andSet(uninitsWhenFalseLeft); |
1210 | break; |
1211 | case JCTree.OR: |
1212 | scanCond(tree.lhs); |
1213 | Bits initsWhenTrueLeft = initsWhenTrue; |
1214 | Bits uninitsWhenTrueLeft = uninitsWhenTrue; |
1215 | inits = initsWhenFalse; |
1216 | uninits = uninitsWhenFalse; |
1217 | scanCond(tree.rhs); |
1218 | initsWhenTrue.andSet(initsWhenTrueLeft); |
1219 | uninitsWhenTrue.andSet(uninitsWhenTrueLeft); |
1220 | break; |
1221 | default: |
1222 | scanExpr(tree.lhs); |
1223 | scanExpr(tree.rhs); |
1224 | } |
1225 | } |
1226 | |
1227 | public void visitIdent(JCIdent tree) { |
1228 | if (tree.sym.kind == VAR) |
1229 | checkInit(tree.pos(), (VarSymbol)tree.sym); |
1230 | } |
1231 | |
1232 | public void visitTypeCast(JCTypeCast tree) { |
1233 | super.visitTypeCast(tree); |
1234 | if (!tree.type.isErroneous() |
1235 | && lint.isEnabled(Lint.LintCategory.CAST) |
1236 | && types.isSameType(tree.expr.type, tree.clazz.type)) { |
1237 | log.warning(tree.pos(), "redundant.cast", tree.expr.type); |
1238 | } |
1239 | } |
1240 | |
1241 | public void visitTopLevel(JCCompilationUnit tree) { |
1242 | // Do nothing for TopLevel since each class is visited individually |
1243 | } |
1244 | |
1245 | /************************************************************************** |
1246 | * main method |
1247 | *************************************************************************/ |
1248 | |
1249 | /** Perform definite assignment/unassignment analysis on a tree. |
1250 | */ |
1251 | public void analyzeTree(JCTree tree, TreeMaker make) { |
1252 | try { |
1253 | this.make = make; |
1254 | inits = new Bits(); |
1255 | uninits = new Bits(); |
1256 | uninitsTry = new Bits(); |
1257 | initsWhenTrue = initsWhenFalse = |
1258 | uninitsWhenTrue = uninitsWhenFalse = null; |
1259 | if (vars == null) |
1260 | vars = new VarSymbol[32]; |
1261 | else |
1262 | for (int i=0; i<vars.length; i++) |
1263 | vars[i] = null; |
1264 | firstadr = 0; |
1265 | nextadr = 0; |
1266 | pendingExits = new ListBuffer<PendingExit>(); |
1267 | alive = true; |
1268 | this.thrown = this.caught = null; |
1269 | this.classDef = null; |
1270 | scan(tree); |
1271 | } finally { |
1272 | // note that recursive invocations of this method fail hard |
1273 | inits = uninits = uninitsTry = null; |
1274 | initsWhenTrue = initsWhenFalse = |
1275 | uninitsWhenTrue = uninitsWhenFalse = null; |
1276 | if (vars != null) for (int i=0; i<vars.length; i++) |
1277 | vars[i] = null; |
1278 | firstadr = 0; |
1279 | nextadr = 0; |
1280 | pendingExits = null; |
1281 | this.make = null; |
1282 | this.thrown = this.caught = null; |
1283 | this.classDef = null; |
1284 | } |
1285 | } |
1286 | } |