| 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 | } |