UninitializedValues.cpp revision e0e29332c89da22b6890929b97e6f568c917d85f
1//==- UninitializedValues.cpp - Find Uninitialized Values -------*- C++ --*-==// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements uninitialized values analysis for source-level CFGs. 11// 12//===----------------------------------------------------------------------===// 13 14#include <utility> 15#include "llvm/ADT/Optional.h" 16#include "llvm/ADT/SmallVector.h" 17#include "llvm/ADT/PackedVector.h" 18#include "llvm/ADT/DenseMap.h" 19#include "clang/AST/Decl.h" 20#include "clang/Analysis/CFG.h" 21#include "clang/Analysis/AnalysisContext.h" 22#include "clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h" 23#include "clang/Analysis/Analyses/UninitializedValues.h" 24#include "clang/Analysis/Support/SaveAndRestore.h" 25 26using namespace clang; 27 28static bool isTrackedVar(const VarDecl *vd, const DeclContext *dc) { 29 if (vd->isLocalVarDecl() && !vd->hasGlobalStorage() && 30 !vd->isExceptionVariable() && 31 vd->getDeclContext() == dc) { 32 QualType ty = vd->getType(); 33 return ty->isScalarType() || ty->isVectorType(); 34 } 35 return false; 36} 37 38//------------------------------------------------------------------------====// 39// DeclToIndex: a mapping from Decls we track to value indices. 40//====------------------------------------------------------------------------// 41 42namespace { 43class DeclToIndex { 44 llvm::DenseMap<const VarDecl *, unsigned> map; 45public: 46 DeclToIndex() {} 47 48 /// Compute the actual mapping from declarations to bits. 49 void computeMap(const DeclContext &dc); 50 51 /// Return the number of declarations in the map. 52 unsigned size() const { return map.size(); } 53 54 /// Returns the bit vector index for a given declaration. 55 llvm::Optional<unsigned> getValueIndex(const VarDecl *d) const; 56}; 57} 58 59void DeclToIndex::computeMap(const DeclContext &dc) { 60 unsigned count = 0; 61 DeclContext::specific_decl_iterator<VarDecl> I(dc.decls_begin()), 62 E(dc.decls_end()); 63 for ( ; I != E; ++I) { 64 const VarDecl *vd = *I; 65 if (isTrackedVar(vd, &dc)) 66 map[vd] = count++; 67 } 68} 69 70llvm::Optional<unsigned> DeclToIndex::getValueIndex(const VarDecl *d) const { 71 llvm::DenseMap<const VarDecl *, unsigned>::const_iterator I = map.find(d); 72 if (I == map.end()) 73 return llvm::Optional<unsigned>(); 74 return I->second; 75} 76 77//------------------------------------------------------------------------====// 78// CFGBlockValues: dataflow values for CFG blocks. 79//====------------------------------------------------------------------------// 80 81// These values are defined in such a way that a merge can be done using 82// a bitwise OR. 83enum Value { Unknown = 0x0, /* 00 */ 84 Initialized = 0x1, /* 01 */ 85 Uninitialized = 0x2, /* 10 */ 86 MayUninitialized = 0x3 /* 11 */ }; 87 88static bool isUninitialized(const Value v) { 89 return v >= Uninitialized; 90} 91static bool isAlwaysUninit(const Value v) { 92 return v == Uninitialized; 93} 94 95namespace { 96 97typedef llvm::PackedVector<Value, 2> ValueVector; 98typedef std::pair<ValueVector *, ValueVector *> BVPair; 99 100class CFGBlockValues { 101 const CFG &cfg; 102 BVPair *vals; 103 ValueVector scratch; 104 DeclToIndex declToIndex; 105 106 ValueVector &lazyCreate(ValueVector *&bv); 107public: 108 CFGBlockValues(const CFG &cfg); 109 ~CFGBlockValues(); 110 111 unsigned getNumEntries() const { return declToIndex.size(); } 112 113 void computeSetOfDeclarations(const DeclContext &dc); 114 ValueVector &getValueVector(const CFGBlock *block, 115 const CFGBlock *dstBlock); 116 117 BVPair &getValueVectors(const CFGBlock *block, bool shouldLazyCreate); 118 119 void mergeIntoScratch(ValueVector const &source, bool isFirst); 120 bool updateValueVectorWithScratch(const CFGBlock *block); 121 bool updateValueVectors(const CFGBlock *block, const BVPair &newVals); 122 123 bool hasNoDeclarations() const { 124 return declToIndex.size() == 0; 125 } 126 127 void resetScratch(); 128 ValueVector &getScratch() { return scratch; } 129 130 ValueVector::reference operator[](const VarDecl *vd); 131}; 132} // end anonymous namespace 133 134CFGBlockValues::CFGBlockValues(const CFG &c) : cfg(c), vals(0) { 135 unsigned n = cfg.getNumBlockIDs(); 136 if (!n) 137 return; 138 vals = new std::pair<ValueVector*, ValueVector*>[n]; 139 memset((void*)vals, 0, sizeof(*vals) * n); 140} 141 142CFGBlockValues::~CFGBlockValues() { 143 unsigned n = cfg.getNumBlockIDs(); 144 if (n == 0) 145 return; 146 for (unsigned i = 0; i < n; ++i) { 147 delete vals[i].first; 148 delete vals[i].second; 149 } 150 delete [] vals; 151} 152 153void CFGBlockValues::computeSetOfDeclarations(const DeclContext &dc) { 154 declToIndex.computeMap(dc); 155 scratch.resize(declToIndex.size()); 156} 157 158ValueVector &CFGBlockValues::lazyCreate(ValueVector *&bv) { 159 if (!bv) 160 bv = new ValueVector(declToIndex.size()); 161 return *bv; 162} 163 164/// This function pattern matches for a '&&' or '||' that appears at 165/// the beginning of a CFGBlock that also (1) has a terminator and 166/// (2) has no other elements. If such an expression is found, it is returned. 167static BinaryOperator *getLogicalOperatorInChain(const CFGBlock *block) { 168 if (block->empty()) 169 return 0; 170 171 const CFGStmt *cstmt = block->front().getAs<CFGStmt>(); 172 if (!cstmt) 173 return 0; 174 175 BinaryOperator *b = dyn_cast_or_null<BinaryOperator>(cstmt->getStmt()); 176 177 if (!b || !b->isLogicalOp()) 178 return 0; 179 180 if (block->pred_size() == 2) { 181 if (block->getTerminatorCondition() == b) { 182 if (block->succ_size() == 2) 183 return b; 184 } 185 else if (block->size() == 1) 186 return b; 187 } 188 189 return 0; 190} 191 192ValueVector &CFGBlockValues::getValueVector(const CFGBlock *block, 193 const CFGBlock *dstBlock) { 194 unsigned idx = block->getBlockID(); 195 if (dstBlock && getLogicalOperatorInChain(block)) { 196 if (*block->succ_begin() == dstBlock) 197 return lazyCreate(vals[idx].first); 198 assert(*(block->succ_begin()+1) == dstBlock); 199 return lazyCreate(vals[idx].second); 200 } 201 202 assert(vals[idx].second == 0); 203 return lazyCreate(vals[idx].first); 204} 205 206BVPair &CFGBlockValues::getValueVectors(const clang::CFGBlock *block, 207 bool shouldLazyCreate) { 208 unsigned idx = block->getBlockID(); 209 lazyCreate(vals[idx].first); 210 if (shouldLazyCreate) 211 lazyCreate(vals[idx].second); 212 return vals[idx]; 213} 214 215void CFGBlockValues::mergeIntoScratch(ValueVector const &source, 216 bool isFirst) { 217 if (isFirst) 218 scratch = source; 219 else 220 scratch |= source; 221} 222#if 0 223static void printVector(const CFGBlock *block, ValueVector &bv, 224 unsigned num) { 225 226 llvm::errs() << block->getBlockID() << " :"; 227 for (unsigned i = 0; i < bv.size(); ++i) { 228 llvm::errs() << ' ' << bv[i]; 229 } 230 llvm::errs() << " : " << num << '\n'; 231} 232#endif 233 234bool CFGBlockValues::updateValueVectorWithScratch(const CFGBlock *block) { 235 ValueVector &dst = getValueVector(block, 0); 236 bool changed = (dst != scratch); 237 if (changed) 238 dst = scratch; 239#if 0 240 printVector(block, scratch, 0); 241#endif 242 return changed; 243} 244 245bool CFGBlockValues::updateValueVectors(const CFGBlock *block, 246 const BVPair &newVals) { 247 BVPair &vals = getValueVectors(block, true); 248 bool changed = *newVals.first != *vals.first || 249 *newVals.second != *vals.second; 250 *vals.first = *newVals.first; 251 *vals.second = *newVals.second; 252#if 0 253 printVector(block, *vals.first, 1); 254 printVector(block, *vals.second, 2); 255#endif 256 return changed; 257} 258 259void CFGBlockValues::resetScratch() { 260 scratch.reset(); 261} 262 263ValueVector::reference CFGBlockValues::operator[](const VarDecl *vd) { 264 const llvm::Optional<unsigned> &idx = declToIndex.getValueIndex(vd); 265 assert(idx.hasValue()); 266 return scratch[idx.getValue()]; 267} 268 269//------------------------------------------------------------------------====// 270// Worklist: worklist for dataflow analysis. 271//====------------------------------------------------------------------------// 272 273namespace { 274class DataflowWorklist { 275 SmallVector<const CFGBlock *, 20> worklist; 276 llvm::BitVector enqueuedBlocks; 277public: 278 DataflowWorklist(const CFG &cfg) : enqueuedBlocks(cfg.getNumBlockIDs()) {} 279 280 void enqueueSuccessors(const CFGBlock *block); 281 const CFGBlock *dequeue(); 282}; 283} 284 285void DataflowWorklist::enqueueSuccessors(const clang::CFGBlock *block) { 286 unsigned OldWorklistSize = worklist.size(); 287 for (CFGBlock::const_succ_iterator I = block->succ_begin(), 288 E = block->succ_end(); I != E; ++I) { 289 const CFGBlock *Successor = *I; 290 if (!Successor || enqueuedBlocks[Successor->getBlockID()]) 291 continue; 292 worklist.push_back(Successor); 293 enqueuedBlocks[Successor->getBlockID()] = true; 294 } 295 if (OldWorklistSize == 0 || OldWorklistSize == worklist.size()) 296 return; 297 298 // Rotate the newly added blocks to the start of the worklist so that it forms 299 // a proper queue when we pop off the end of the worklist. 300 std::rotate(worklist.begin(), worklist.begin() + OldWorklistSize, 301 worklist.end()); 302} 303 304const CFGBlock *DataflowWorklist::dequeue() { 305 if (worklist.empty()) 306 return 0; 307 const CFGBlock *b = worklist.back(); 308 worklist.pop_back(); 309 enqueuedBlocks[b->getBlockID()] = false; 310 return b; 311} 312 313//------------------------------------------------------------------------====// 314// Transfer function for uninitialized values analysis. 315//====------------------------------------------------------------------------// 316 317namespace { 318class FindVarResult { 319 const VarDecl *vd; 320 const DeclRefExpr *dr; 321public: 322 FindVarResult(VarDecl *vd, DeclRefExpr *dr) : vd(vd), dr(dr) {} 323 324 const DeclRefExpr *getDeclRefExpr() const { return dr; } 325 const VarDecl *getDecl() const { return vd; } 326}; 327 328class TransferFunctions : public StmtVisitor<TransferFunctions> { 329 CFGBlockValues &vals; 330 const CFG &cfg; 331 AnalysisContext ∾ 332 UninitVariablesHandler *handler; 333 const bool flagBlockUses; 334 335 /// The last DeclRefExpr seen when analyzing a block. Used to 336 /// cheat when detecting cases when the address of a variable is taken. 337 DeclRefExpr *lastDR; 338 339 /// The last lvalue-to-rvalue conversion of a variable whose value 340 /// was uninitialized. Normally this results in a warning, but it is 341 /// possible to either silence the warning in some cases, or we 342 /// propagate the uninitialized value. 343 CastExpr *lastLoad; 344 345 /// For some expressions, we want to ignore any post-processing after 346 /// visitation. 347 bool skipProcessUses; 348 349public: 350 TransferFunctions(CFGBlockValues &vals, const CFG &cfg, 351 AnalysisContext &ac, 352 UninitVariablesHandler *handler, 353 bool flagBlockUses) 354 : vals(vals), cfg(cfg), ac(ac), handler(handler), 355 flagBlockUses(flagBlockUses), lastDR(0), lastLoad(0), 356 skipProcessUses(false) {} 357 358 void reportUninit(const DeclRefExpr *ex, const VarDecl *vd, 359 bool isAlwaysUninit); 360 361 void VisitBlockExpr(BlockExpr *be); 362 void VisitDeclStmt(DeclStmt *ds); 363 void VisitDeclRefExpr(DeclRefExpr *dr); 364 void VisitUnaryOperator(UnaryOperator *uo); 365 void VisitBinaryOperator(BinaryOperator *bo); 366 void VisitCastExpr(CastExpr *ce); 367 void VisitObjCForCollectionStmt(ObjCForCollectionStmt *fs); 368 void Visit(Stmt *s); 369 370 bool isTrackedVar(const VarDecl *vd) { 371 return ::isTrackedVar(vd, cast<DeclContext>(ac.getDecl())); 372 } 373 374 FindVarResult findBlockVarDecl(Expr *ex); 375 376 void ProcessUses(Stmt *s = 0); 377}; 378} 379 380static const Expr *stripCasts(ASTContext &C, const Expr *Ex) { 381 while (Ex) { 382 Ex = Ex->IgnoreParenNoopCasts(C); 383 if (const CastExpr *CE = dyn_cast<CastExpr>(Ex)) { 384 if (CE->getCastKind() == CK_LValueBitCast) { 385 Ex = CE->getSubExpr(); 386 continue; 387 } 388 } 389 break; 390 } 391 return Ex; 392} 393 394void TransferFunctions::reportUninit(const DeclRefExpr *ex, 395 const VarDecl *vd, bool isAlwaysUnit) { 396 if (handler) handler->handleUseOfUninitVariable(ex, vd, isAlwaysUnit); 397} 398 399FindVarResult TransferFunctions::findBlockVarDecl(Expr *ex) { 400 if (DeclRefExpr *dr = dyn_cast<DeclRefExpr>(ex->IgnoreParenCasts())) 401 if (VarDecl *vd = dyn_cast<VarDecl>(dr->getDecl())) 402 if (isTrackedVar(vd)) 403 return FindVarResult(vd, dr); 404 return FindVarResult(0, 0); 405} 406 407void TransferFunctions::VisitObjCForCollectionStmt(ObjCForCollectionStmt *fs) { 408 // This represents an initialization of the 'element' value. 409 Stmt *element = fs->getElement(); 410 const VarDecl *vd = 0; 411 412 if (DeclStmt *ds = dyn_cast<DeclStmt>(element)) { 413 vd = cast<VarDecl>(ds->getSingleDecl()); 414 if (!isTrackedVar(vd)) 415 vd = 0; 416 } else { 417 // Initialize the value of the reference variable. 418 const FindVarResult &res = findBlockVarDecl(cast<Expr>(element)); 419 vd = res.getDecl(); 420 } 421 422 if (vd) 423 vals[vd] = Initialized; 424} 425 426void TransferFunctions::VisitBlockExpr(BlockExpr *be) { 427 if (!flagBlockUses || !handler) 428 return; 429 const BlockDecl *bd = be->getBlockDecl(); 430 for (BlockDecl::capture_const_iterator i = bd->capture_begin(), 431 e = bd->capture_end() ; i != e; ++i) { 432 const VarDecl *vd = i->getVariable(); 433 if (!vd->hasLocalStorage()) 434 continue; 435 if (!isTrackedVar(vd)) 436 continue; 437 if (i->isByRef()) { 438 vals[vd] = Initialized; 439 continue; 440 } 441 Value v = vals[vd]; 442 if (isUninitialized(v)) 443 handler->handleUseOfUninitVariable(be, vd, isAlwaysUninit(v)); 444 } 445} 446 447void TransferFunctions::VisitDeclRefExpr(DeclRefExpr *dr) { 448 // Record the last DeclRefExpr seen. This is an lvalue computation. 449 // We use this value to later detect if a variable "escapes" the analysis. 450 if (const VarDecl *vd = dyn_cast<VarDecl>(dr->getDecl())) 451 if (isTrackedVar(vd)) { 452 ProcessUses(); 453 lastDR = dr; 454 } 455} 456 457void TransferFunctions::VisitDeclStmt(DeclStmt *ds) { 458 for (DeclStmt::decl_iterator DI = ds->decl_begin(), DE = ds->decl_end(); 459 DI != DE; ++DI) { 460 if (VarDecl *vd = dyn_cast<VarDecl>(*DI)) { 461 if (isTrackedVar(vd)) { 462 if (Expr *init = vd->getInit()) { 463 // If the initializer consists solely of a reference to itself, we 464 // explicitly mark the variable as uninitialized. This allows code 465 // like the following: 466 // 467 // int x = x; 468 // 469 // to deliberately leave a variable uninitialized. Different analysis 470 // clients can detect this pattern and adjust their reporting 471 // appropriately, but we need to continue to analyze subsequent uses 472 // of the variable. 473 if (init == lastLoad) { 474 const DeclRefExpr *DR 475 = cast<DeclRefExpr>(stripCasts(ac.getASTContext(), 476 lastLoad->getSubExpr())); 477 if (DR->getDecl() == vd) { 478 // int x = x; 479 // Propagate uninitialized value, but don't immediately report 480 // a problem. 481 vals[vd] = Uninitialized; 482 lastLoad = 0; 483 lastDR = 0; 484 return; 485 } 486 } 487 488 // All other cases: treat the new variable as initialized. 489 vals[vd] = Initialized; 490 } 491 } 492 } 493 } 494} 495 496void TransferFunctions::VisitBinaryOperator(clang::BinaryOperator *bo) { 497 if (bo->isAssignmentOp()) { 498 const FindVarResult &res = findBlockVarDecl(bo->getLHS()); 499 if (const VarDecl *vd = res.getDecl()) { 500 ValueVector::reference val = vals[vd]; 501 if (isUninitialized(val)) { 502 if (bo->getOpcode() != BO_Assign) 503 reportUninit(res.getDeclRefExpr(), vd, isAlwaysUninit(val)); 504 else 505 val = Initialized; 506 } 507 } 508 } 509} 510 511void TransferFunctions::VisitUnaryOperator(clang::UnaryOperator *uo) { 512 switch (uo->getOpcode()) { 513 case clang::UO_PostDec: 514 case clang::UO_PostInc: 515 case clang::UO_PreDec: 516 case clang::UO_PreInc: { 517 const FindVarResult &res = findBlockVarDecl(uo->getSubExpr()); 518 if (const VarDecl *vd = res.getDecl()) { 519 assert(res.getDeclRefExpr() == lastDR); 520 // We null out lastDR to indicate we have fully processed it 521 // and we don't want the auto-value setting in Visit(). 522 lastDR = 0; 523 524 ValueVector::reference val = vals[vd]; 525 if (isUninitialized(val)) 526 reportUninit(res.getDeclRefExpr(), vd, isAlwaysUninit(val)); 527 } 528 break; 529 } 530 default: 531 break; 532 } 533} 534 535void TransferFunctions::VisitCastExpr(clang::CastExpr *ce) { 536 if (ce->getCastKind() == CK_LValueToRValue) { 537 const FindVarResult &res = findBlockVarDecl(ce->getSubExpr()); 538 if (const VarDecl *vd = res.getDecl()) { 539 assert(res.getDeclRefExpr() == lastDR); 540 if (isUninitialized(vals[vd])) { 541 // Record this load of an uninitialized value. Normally this 542 // results in a warning, but we delay reporting the issue 543 // in case it is wrapped in a void cast, etc. 544 lastLoad = ce; 545 } 546 } 547 } 548 else if (ce->getCastKind() == CK_NoOp || 549 ce->getCastKind() == CK_LValueBitCast) { 550 skipProcessUses = true; 551 } 552 else if (CStyleCastExpr *cse = dyn_cast<CStyleCastExpr>(ce)) { 553 if (cse->getType()->isVoidType()) { 554 // e.g. (void) x; 555 if (lastLoad == cse->getSubExpr()) { 556 // Squelch any detected load of an uninitialized value if 557 // we cast it to void. 558 lastLoad = 0; 559 lastDR = 0; 560 } 561 } 562 } 563} 564 565void TransferFunctions::Visit(clang::Stmt *s) { 566 skipProcessUses = false; 567 StmtVisitor<TransferFunctions>::Visit(s); 568 if (!skipProcessUses) 569 ProcessUses(s); 570} 571 572void TransferFunctions::ProcessUses(Stmt *s) { 573 // This method is typically called after visiting a CFGElement statement 574 // in the CFG. We delay processing of reporting many loads of uninitialized 575 // values until here. 576 if (lastLoad) { 577 // If we just visited the lvalue-to-rvalue cast, there is nothing 578 // left to do. 579 if (lastLoad == s) 580 return; 581 582 // If we reach here, we have seen a load of an uninitialized value 583 // and it hasn't been casted to void or otherwise handled. In this 584 // situation, report the incident. 585 const DeclRefExpr *DR = 586 cast<DeclRefExpr>(stripCasts(ac.getASTContext(), 587 lastLoad->getSubExpr())); 588 const VarDecl *VD = cast<VarDecl>(DR->getDecl()); 589 reportUninit(DR, VD, isAlwaysUninit(vals[VD])); 590 lastLoad = 0; 591 592 if (DR == lastDR) { 593 lastDR = 0; 594 return; 595 } 596 } 597 598 // Any other uses of 'lastDR' involve taking an lvalue of variable. 599 // In this case, it "escapes" the analysis. 600 if (lastDR && lastDR != s) { 601 vals[cast<VarDecl>(lastDR->getDecl())] = Initialized; 602 lastDR = 0; 603 } 604} 605 606//------------------------------------------------------------------------====// 607// High-level "driver" logic for uninitialized values analysis. 608//====------------------------------------------------------------------------// 609 610static bool runOnBlock(const CFGBlock *block, const CFG &cfg, 611 AnalysisContext &ac, CFGBlockValues &vals, 612 llvm::BitVector &wasAnalyzed, 613 UninitVariablesHandler *handler = 0, 614 bool flagBlockUses = false) { 615 616 wasAnalyzed[block->getBlockID()] = true; 617 618 if (const BinaryOperator *b = getLogicalOperatorInChain(block)) { 619 CFGBlock::const_pred_iterator itr = block->pred_begin(); 620 BVPair vA = vals.getValueVectors(*itr, false); 621 ++itr; 622 BVPair vB = vals.getValueVectors(*itr, false); 623 624 BVPair valsAB; 625 626 if (b->getOpcode() == BO_LAnd) { 627 // Merge the 'F' bits from the first and second. 628 vals.mergeIntoScratch(*(vA.second ? vA.second : vA.first), true); 629 vals.mergeIntoScratch(*(vB.second ? vB.second : vB.first), false); 630 valsAB.first = vA.first; 631 valsAB.second = &vals.getScratch(); 632 } else { 633 // Merge the 'T' bits from the first and second. 634 assert(b->getOpcode() == BO_LOr); 635 vals.mergeIntoScratch(*vA.first, true); 636 vals.mergeIntoScratch(*vB.first, false); 637 valsAB.first = &vals.getScratch(); 638 valsAB.second = vA.second ? vA.second : vA.first; 639 } 640 return vals.updateValueVectors(block, valsAB); 641 } 642 643 // Default behavior: merge in values of predecessor blocks. 644 vals.resetScratch(); 645 bool isFirst = true; 646 for (CFGBlock::const_pred_iterator I = block->pred_begin(), 647 E = block->pred_end(); I != E; ++I) { 648 vals.mergeIntoScratch(vals.getValueVector(*I, block), isFirst); 649 isFirst = false; 650 } 651 // Apply the transfer function. 652 TransferFunctions tf(vals, cfg, ac, handler, flagBlockUses); 653 for (CFGBlock::const_iterator I = block->begin(), E = block->end(); 654 I != E; ++I) { 655 if (const CFGStmt *cs = dyn_cast<CFGStmt>(&*I)) { 656 tf.Visit(cs->getStmt()); 657 } 658 } 659 tf.ProcessUses(); 660 return vals.updateValueVectorWithScratch(block); 661} 662 663void clang::runUninitializedVariablesAnalysis( 664 const DeclContext &dc, 665 const CFG &cfg, 666 AnalysisContext &ac, 667 UninitVariablesHandler &handler, 668 UninitVariablesAnalysisStats &stats) { 669 CFGBlockValues vals(cfg); 670 vals.computeSetOfDeclarations(dc); 671 if (vals.hasNoDeclarations()) 672 return; 673 674 stats.NumVariablesAnalyzed = vals.getNumEntries(); 675 676 // Mark all variables uninitialized at the entry. 677 const CFGBlock &entry = cfg.getEntry(); 678 for (CFGBlock::const_succ_iterator i = entry.succ_begin(), 679 e = entry.succ_end(); i != e; ++i) { 680 if (const CFGBlock *succ = *i) { 681 ValueVector &vec = vals.getValueVector(&entry, succ); 682 const unsigned n = vals.getNumEntries(); 683 for (unsigned j = 0; j < n ; ++j) { 684 vec[j] = Uninitialized; 685 } 686 } 687 } 688 689 // Proceed with the workist. 690 DataflowWorklist worklist(cfg); 691 llvm::BitVector previouslyVisited(cfg.getNumBlockIDs()); 692 worklist.enqueueSuccessors(&cfg.getEntry()); 693 llvm::BitVector wasAnalyzed(cfg.getNumBlockIDs(), false); 694 695 while (const CFGBlock *block = worklist.dequeue()) { 696 // Did the block change? 697 bool changed = runOnBlock(block, cfg, ac, vals, wasAnalyzed); 698 ++stats.NumBlockVisits; 699 if (changed || !previouslyVisited[block->getBlockID()]) 700 worklist.enqueueSuccessors(block); 701 previouslyVisited[block->getBlockID()] = true; 702 } 703 704 // Run through the blocks one more time, and report uninitialized variabes. 705 for (CFG::const_iterator BI = cfg.begin(), BE = cfg.end(); BI != BE; ++BI) { 706 if (wasAnalyzed[(*BI)->getBlockID()]) { 707 runOnBlock(*BI, cfg, ac, vals, wasAnalyzed, &handler, 708 /* flagBlockUses */ true); 709 ++stats.NumBlockVisits; 710 } 711 } 712} 713 714UninitVariablesHandler::~UninitVariablesHandler() {} 715