ExprEngineC.cpp revision 3056439bb175db8c46b89fb4385de8b3a8e42d0d
1//=-- ExprEngineC.cpp - ExprEngine support for C expressions ----*- 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 defines ExprEngine's support for C expressions. 11// 12//===----------------------------------------------------------------------===// 13 14#include "clang/AST/ExprCXX.h" 15#include "clang/StaticAnalyzer/Core/CheckerManager.h" 16#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 17 18using namespace clang; 19using namespace ento; 20using llvm::APSInt; 21 22void ExprEngine::VisitBinaryOperator(const BinaryOperator* B, 23 ExplodedNode *Pred, 24 ExplodedNodeSet &Dst) { 25 26 Expr *LHS = B->getLHS()->IgnoreParens(); 27 Expr *RHS = B->getRHS()->IgnoreParens(); 28 29 // FIXME: Prechecks eventually go in ::Visit(). 30 ExplodedNodeSet CheckedSet; 31 ExplodedNodeSet Tmp2; 32 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this); 33 34 // With both the LHS and RHS evaluated, process the operation itself. 35 for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end(); 36 it != ei; ++it) { 37 38 ProgramStateRef state = (*it)->getState(); 39 const LocationContext *LCtx = (*it)->getLocationContext(); 40 SVal LeftV = state->getSVal(LHS, LCtx); 41 SVal RightV = state->getSVal(RHS, LCtx); 42 43 BinaryOperator::Opcode Op = B->getOpcode(); 44 45 if (Op == BO_Assign) { 46 // EXPERIMENTAL: "Conjured" symbols. 47 // FIXME: Handle structs. 48 if (RightV.isUnknown()) { 49 unsigned Count = currBldrCtx->blockCount(); 50 RightV = svalBuilder.conjureSymbolVal(0, B->getRHS(), LCtx, Count); 51 } 52 // Simulate the effects of a "store": bind the value of the RHS 53 // to the L-Value represented by the LHS. 54 SVal ExprVal = B->isGLValue() ? LeftV : RightV; 55 evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal), 56 LeftV, RightV); 57 continue; 58 } 59 60 if (!B->isAssignmentOp()) { 61 StmtNodeBuilder Bldr(*it, Tmp2, *currBldrCtx); 62 63 if (B->isAdditiveOp()) { 64 // If one of the operands is a location, conjure a symbol for the other 65 // one (offset) if it's unknown so that memory arithmetic always 66 // results in an ElementRegion. 67 // TODO: This can be removed after we enable history tracking with 68 // SymSymExpr. 69 unsigned Count = currBldrCtx->blockCount(); 70 if (LeftV.getAs<Loc>() && 71 RHS->getType()->isIntegralOrEnumerationType() && 72 RightV.isUnknown()) { 73 RightV = svalBuilder.conjureSymbolVal(RHS, LCtx, RHS->getType(), 74 Count); 75 } 76 if (RightV.getAs<Loc>() && 77 LHS->getType()->isIntegralOrEnumerationType() && 78 LeftV.isUnknown()) { 79 LeftV = svalBuilder.conjureSymbolVal(LHS, LCtx, LHS->getType(), 80 Count); 81 } 82 } 83 84 // Process non-assignments except commas or short-circuited 85 // logical expressions (LAnd and LOr). 86 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType()); 87 if (Result.isUnknown()) { 88 Bldr.generateNode(B, *it, state); 89 continue; 90 } 91 92 state = state->BindExpr(B, LCtx, Result); 93 Bldr.generateNode(B, *it, state); 94 continue; 95 } 96 97 assert (B->isCompoundAssignmentOp()); 98 99 switch (Op) { 100 default: 101 llvm_unreachable("Invalid opcode for compound assignment."); 102 case BO_MulAssign: Op = BO_Mul; break; 103 case BO_DivAssign: Op = BO_Div; break; 104 case BO_RemAssign: Op = BO_Rem; break; 105 case BO_AddAssign: Op = BO_Add; break; 106 case BO_SubAssign: Op = BO_Sub; break; 107 case BO_ShlAssign: Op = BO_Shl; break; 108 case BO_ShrAssign: Op = BO_Shr; break; 109 case BO_AndAssign: Op = BO_And; break; 110 case BO_XorAssign: Op = BO_Xor; break; 111 case BO_OrAssign: Op = BO_Or; break; 112 } 113 114 // Perform a load (the LHS). This performs the checks for 115 // null dereferences, and so on. 116 ExplodedNodeSet Tmp; 117 SVal location = LeftV; 118 evalLoad(Tmp, B, LHS, *it, state, location); 119 120 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; 121 ++I) { 122 123 state = (*I)->getState(); 124 const LocationContext *LCtx = (*I)->getLocationContext(); 125 SVal V = state->getSVal(LHS, LCtx); 126 127 // Get the computation type. 128 QualType CTy = 129 cast<CompoundAssignOperator>(B)->getComputationResultType(); 130 CTy = getContext().getCanonicalType(CTy); 131 132 QualType CLHSTy = 133 cast<CompoundAssignOperator>(B)->getComputationLHSType(); 134 CLHSTy = getContext().getCanonicalType(CLHSTy); 135 136 QualType LTy = getContext().getCanonicalType(LHS->getType()); 137 138 // Promote LHS. 139 V = svalBuilder.evalCast(V, CLHSTy, LTy); 140 141 // Compute the result of the operation. 142 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy), 143 B->getType(), CTy); 144 145 // EXPERIMENTAL: "Conjured" symbols. 146 // FIXME: Handle structs. 147 148 SVal LHSVal; 149 150 if (Result.isUnknown()) { 151 // The symbolic value is actually for the type of the left-hand side 152 // expression, not the computation type, as this is the value the 153 // LValue on the LHS will bind to. 154 LHSVal = svalBuilder.conjureSymbolVal(0, B->getRHS(), LCtx, LTy, 155 currBldrCtx->blockCount()); 156 // However, we need to convert the symbol to the computation type. 157 Result = svalBuilder.evalCast(LHSVal, CTy, LTy); 158 } 159 else { 160 // The left-hand side may bind to a different value then the 161 // computation type. 162 LHSVal = svalBuilder.evalCast(Result, LTy, CTy); 163 } 164 165 // In C++, assignment and compound assignment operators return an 166 // lvalue. 167 if (B->isGLValue()) 168 state = state->BindExpr(B, LCtx, location); 169 else 170 state = state->BindExpr(B, LCtx, Result); 171 172 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal); 173 } 174 } 175 176 // FIXME: postvisits eventually go in ::Visit() 177 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this); 178} 179 180void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred, 181 ExplodedNodeSet &Dst) { 182 183 CanQualType T = getContext().getCanonicalType(BE->getType()); 184 185 // Get the value of the block itself. 186 SVal V = svalBuilder.getBlockPointer(BE->getBlockDecl(), T, 187 Pred->getLocationContext()); 188 189 ProgramStateRef State = Pred->getState(); 190 191 // If we created a new MemRegion for the block, we should explicitly bind 192 // the captured variables. 193 if (const BlockDataRegion *BDR = 194 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) { 195 196 BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(), 197 E = BDR->referenced_vars_end(); 198 199 for (; I != E; ++I) { 200 const MemRegion *capturedR = I.getCapturedRegion(); 201 const MemRegion *originalR = I.getOriginalRegion(); 202 if (capturedR != originalR) { 203 SVal originalV = State->getSVal(loc::MemRegionVal(originalR)); 204 State = State->bindLoc(loc::MemRegionVal(capturedR), originalV); 205 } 206 } 207 } 208 209 ExplodedNodeSet Tmp; 210 StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx); 211 Bldr.generateNode(BE, Pred, 212 State->BindExpr(BE, Pred->getLocationContext(), V), 213 0, ProgramPoint::PostLValueKind); 214 215 // FIXME: Move all post/pre visits to ::Visit(). 216 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this); 217} 218 219void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, 220 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 221 222 ExplodedNodeSet dstPreStmt; 223 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this); 224 225 if (CastE->getCastKind() == CK_LValueToRValue) { 226 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 227 I!=E; ++I) { 228 ExplodedNode *subExprNode = *I; 229 ProgramStateRef state = subExprNode->getState(); 230 const LocationContext *LCtx = subExprNode->getLocationContext(); 231 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx)); 232 } 233 return; 234 } 235 236 // All other casts. 237 QualType T = CastE->getType(); 238 QualType ExTy = Ex->getType(); 239 240 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE)) 241 T = ExCast->getTypeAsWritten(); 242 243 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx); 244 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 245 I != E; ++I) { 246 247 Pred = *I; 248 ProgramStateRef state = Pred->getState(); 249 const LocationContext *LCtx = Pred->getLocationContext(); 250 251 switch (CastE->getCastKind()) { 252 case CK_LValueToRValue: 253 llvm_unreachable("LValueToRValue casts handled earlier."); 254 case CK_ToVoid: 255 continue; 256 // The analyzer doesn't do anything special with these casts, 257 // since it understands retain/release semantics already. 258 case CK_ARCProduceObject: 259 case CK_ARCConsumeObject: 260 case CK_ARCReclaimReturnedObject: 261 case CK_ARCExtendBlockObject: // Fall-through. 262 case CK_CopyAndAutoreleaseBlockObject: 263 // The analyser can ignore atomic casts for now, although some future 264 // checkers may want to make certain that you're not modifying the same 265 // value through atomic and nonatomic pointers. 266 case CK_AtomicToNonAtomic: 267 case CK_NonAtomicToAtomic: 268 // True no-ops. 269 case CK_NoOp: 270 case CK_ConstructorConversion: 271 case CK_UserDefinedConversion: 272 case CK_FunctionToPointerDecay: 273 case CK_BuiltinFnToFnPtr: { 274 // Copy the SVal of Ex to CastE. 275 ProgramStateRef state = Pred->getState(); 276 const LocationContext *LCtx = Pred->getLocationContext(); 277 SVal V = state->getSVal(Ex, LCtx); 278 state = state->BindExpr(CastE, LCtx, V); 279 Bldr.generateNode(CastE, Pred, state); 280 continue; 281 } 282 case CK_MemberPointerToBoolean: 283 // FIXME: For now, member pointers are represented by void *. 284 // FALLTHROUGH 285 case CK_Dependent: 286 case CK_ArrayToPointerDecay: 287 case CK_BitCast: 288 case CK_IntegralCast: 289 case CK_NullToPointer: 290 case CK_IntegralToPointer: 291 case CK_PointerToIntegral: 292 case CK_PointerToBoolean: 293 case CK_IntegralToBoolean: 294 case CK_IntegralToFloating: 295 case CK_FloatingToIntegral: 296 case CK_FloatingToBoolean: 297 case CK_FloatingCast: 298 case CK_FloatingRealToComplex: 299 case CK_FloatingComplexToReal: 300 case CK_FloatingComplexToBoolean: 301 case CK_FloatingComplexCast: 302 case CK_FloatingComplexToIntegralComplex: 303 case CK_IntegralRealToComplex: 304 case CK_IntegralComplexToReal: 305 case CK_IntegralComplexToBoolean: 306 case CK_IntegralComplexCast: 307 case CK_IntegralComplexToFloatingComplex: 308 case CK_CPointerToObjCPointerCast: 309 case CK_BlockPointerToObjCPointerCast: 310 case CK_AnyPointerToBlockPointerCast: 311 case CK_ObjCObjectLValueCast: 312 case CK_ZeroToOCLEvent: 313 case CK_LValueBitCast: { 314 // Delegate to SValBuilder to process. 315 SVal V = state->getSVal(Ex, LCtx); 316 V = svalBuilder.evalCast(V, T, ExTy); 317 state = state->BindExpr(CastE, LCtx, V); 318 Bldr.generateNode(CastE, Pred, state); 319 continue; 320 } 321 case CK_DerivedToBase: 322 case CK_UncheckedDerivedToBase: { 323 // For DerivedToBase cast, delegate to the store manager. 324 SVal val = state->getSVal(Ex, LCtx); 325 val = getStoreManager().evalDerivedToBase(val, CastE); 326 state = state->BindExpr(CastE, LCtx, val); 327 Bldr.generateNode(CastE, Pred, state); 328 continue; 329 } 330 // Handle C++ dyn_cast. 331 case CK_Dynamic: { 332 SVal val = state->getSVal(Ex, LCtx); 333 334 // Compute the type of the result. 335 QualType resultType = CastE->getType(); 336 if (CastE->isGLValue()) 337 resultType = getContext().getPointerType(resultType); 338 339 bool Failed = false; 340 341 // Check if the value being cast evaluates to 0. 342 if (val.isZeroConstant()) 343 Failed = true; 344 // Else, evaluate the cast. 345 else 346 val = getStoreManager().evalDynamicCast(val, T, Failed); 347 348 if (Failed) { 349 if (T->isReferenceType()) { 350 // A bad_cast exception is thrown if input value is a reference. 351 // Currently, we model this, by generating a sink. 352 Bldr.generateSink(CastE, Pred, state); 353 continue; 354 } else { 355 // If the cast fails on a pointer, bind to 0. 356 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 357 } 358 } else { 359 // If we don't know if the cast succeeded, conjure a new symbol. 360 if (val.isUnknown()) { 361 DefinedOrUnknownSVal NewSym = 362 svalBuilder.conjureSymbolVal(0, CastE, LCtx, resultType, 363 currBldrCtx->blockCount()); 364 state = state->BindExpr(CastE, LCtx, NewSym); 365 } else 366 // Else, bind to the derived region value. 367 state = state->BindExpr(CastE, LCtx, val); 368 } 369 Bldr.generateNode(CastE, Pred, state); 370 continue; 371 } 372 case CK_NullToMemberPointer: { 373 // FIXME: For now, member pointers are represented by void *. 374 SVal V = svalBuilder.makeIntValWithPtrWidth(0, true); 375 state = state->BindExpr(CastE, LCtx, V); 376 Bldr.generateNode(CastE, Pred, state); 377 continue; 378 } 379 // Various C++ casts that are not handled yet. 380 case CK_ToUnion: 381 case CK_BaseToDerived: 382 case CK_BaseToDerivedMemberPointer: 383 case CK_DerivedToBaseMemberPointer: 384 case CK_ReinterpretMemberPointer: 385 case CK_VectorSplat: { 386 // Recover some path-sensitivty by conjuring a new value. 387 QualType resultType = CastE->getType(); 388 if (CastE->isGLValue()) 389 resultType = getContext().getPointerType(resultType); 390 SVal result = svalBuilder.conjureSymbolVal(0, CastE, LCtx, 391 resultType, 392 currBldrCtx->blockCount()); 393 state = state->BindExpr(CastE, LCtx, result); 394 Bldr.generateNode(CastE, Pred, state); 395 continue; 396 } 397 } 398 } 399} 400 401void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 402 ExplodedNode *Pred, 403 ExplodedNodeSet &Dst) { 404 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 405 406 ProgramStateRef State = Pred->getState(); 407 const LocationContext *LCtx = Pred->getLocationContext(); 408 409 const Expr *Init = CL->getInitializer(); 410 SVal V = State->getSVal(CL->getInitializer(), LCtx); 411 412 if (isa<CXXConstructExpr>(Init)) { 413 // No work needed. Just pass the value up to this expression. 414 } else { 415 assert(isa<InitListExpr>(Init)); 416 Loc CLLoc = State->getLValue(CL, LCtx); 417 State = State->bindLoc(CLLoc, V); 418 419 // Compound literal expressions are a GNU extension in C++. 420 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, 421 // and like temporary objects created by the functional notation T() 422 // CLs are destroyed at the end of the containing full-expression. 423 // HOWEVER, an rvalue of array type is not something the analyzer can 424 // reason about, since we expect all regions to be wrapped in Locs. 425 // So we treat array CLs as lvalues as well, knowing that they will decay 426 // to pointers as soon as they are used. 427 if (CL->isGLValue() || CL->getType()->isArrayType()) 428 V = CLLoc; 429 } 430 431 B.generateNode(CL, Pred, State->BindExpr(CL, LCtx, V)); 432} 433 434void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 435 ExplodedNodeSet &Dst) { 436 // Assumption: The CFG has one DeclStmt per Decl. 437 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin()); 438 439 if (!VD) { 440 //TODO:AZ: remove explicit insertion after refactoring is done. 441 Dst.insert(Pred); 442 return; 443 } 444 445 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 446 ExplodedNodeSet dstPreVisit; 447 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 448 449 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 450 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 451 I!=E; ++I) { 452 ExplodedNode *N = *I; 453 ProgramStateRef state = N->getState(); 454 const LocationContext *LC = N->getLocationContext(); 455 456 // Decls without InitExpr are not initialized explicitly. 457 if (const Expr *InitEx = VD->getInit()) { 458 459 // Note in the state that the initialization has occurred. 460 ExplodedNode *UpdatedN = N; 461 SVal InitVal = state->getSVal(InitEx, LC); 462 463 if (isa<CXXConstructExpr>(InitEx->IgnoreImplicit())) { 464 // We constructed the object directly in the variable. 465 // No need to bind anything. 466 B.generateNode(DS, UpdatedN, state); 467 } else { 468 // We bound the temp obj region to the CXXConstructExpr. Now recover 469 // the lazy compound value when the variable is not a reference. 470 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 471 !VD->getType()->isReferenceType()) { 472 if (Optional<loc::MemRegionVal> M = 473 InitVal.getAs<loc::MemRegionVal>()) { 474 InitVal = state->getSVal(M->getRegion()); 475 assert(InitVal.getAs<nonloc::LazyCompoundVal>()); 476 } 477 } 478 479 // Recover some path-sensitivity if a scalar value evaluated to 480 // UnknownVal. 481 if (InitVal.isUnknown()) { 482 QualType Ty = InitEx->getType(); 483 if (InitEx->isGLValue()) { 484 Ty = getContext().getPointerType(Ty); 485 } 486 487 InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, 488 currBldrCtx->blockCount()); 489 } 490 491 492 B.takeNodes(UpdatedN); 493 ExplodedNodeSet Dst2; 494 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true); 495 B.addNodes(Dst2); 496 } 497 } 498 else { 499 B.generateNode(DS, N, state); 500 } 501 } 502} 503 504void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 505 ExplodedNodeSet &Dst) { 506 assert(B->getOpcode() == BO_LAnd || 507 B->getOpcode() == BO_LOr); 508 509 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 510 ProgramStateRef state = Pred->getState(); 511 512 ExplodedNode *N = Pred; 513 while (!N->getLocation().getAs<BlockEntrance>()) { 514 ProgramPoint P = N->getLocation(); 515 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>()); 516 (void) P; 517 assert(N->pred_size() == 1); 518 N = *N->pred_begin(); 519 } 520 assert(N->pred_size() == 1); 521 N = *N->pred_begin(); 522 BlockEdge BE = N->getLocation().castAs<BlockEdge>(); 523 SVal X; 524 525 // Determine the value of the expression by introspecting how we 526 // got this location in the CFG. This requires looking at the previous 527 // block we were in and what kind of control-flow transfer was involved. 528 const CFGBlock *SrcBlock = BE.getSrc(); 529 // The only terminator (if there is one) that makes sense is a logical op. 530 CFGTerminator T = SrcBlock->getTerminator(); 531 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { 532 (void) Term; 533 assert(Term->isLogicalOp()); 534 assert(SrcBlock->succ_size() == 2); 535 // Did we take the true or false branch? 536 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; 537 X = svalBuilder.makeIntVal(constant, B->getType()); 538 } 539 else { 540 // If there is no terminator, by construction the last statement 541 // in SrcBlock is the value of the enclosing expression. 542 // However, we still need to constrain that value to be 0 or 1. 543 assert(!SrcBlock->empty()); 544 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>(); 545 const Expr *RHS = cast<Expr>(Elem.getStmt()); 546 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); 547 548 if (RHSVal.isUndef()) { 549 X = RHSVal; 550 } else { 551 DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>(); 552 ProgramStateRef StTrue, StFalse; 553 llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); 554 if (StTrue) { 555 if (StFalse) { 556 // We can't constrain the value to 0 or 1. 557 // The best we can do is a cast. 558 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); 559 } else { 560 // The value is known to be true. 561 X = getSValBuilder().makeIntVal(1, B->getType()); 562 } 563 } else { 564 // The value is known to be false. 565 assert(StFalse && "Infeasible path!"); 566 X = getSValBuilder().makeIntVal(0, B->getType()); 567 } 568 } 569 } 570 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); 571} 572 573void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 574 ExplodedNode *Pred, 575 ExplodedNodeSet &Dst) { 576 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 577 578 ProgramStateRef state = Pred->getState(); 579 const LocationContext *LCtx = Pred->getLocationContext(); 580 QualType T = getContext().getCanonicalType(IE->getType()); 581 unsigned NumInitElements = IE->getNumInits(); 582 583 if (T->isArrayType() || T->isRecordType() || T->isVectorType() || 584 T->isAnyComplexType()) { 585 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 586 587 // Handle base case where the initializer has no elements. 588 // e.g: static int* myArray[] = {}; 589 if (NumInitElements == 0) { 590 SVal V = svalBuilder.makeCompoundVal(T, vals); 591 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 592 return; 593 } 594 595 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 596 ei = IE->rend(); it != ei; ++it) { 597 SVal V = state->getSVal(cast<Expr>(*it), LCtx); 598 if (dyn_cast_or_null<CXXTempObjectRegion>(V.getAsRegion())) 599 V = UnknownVal(); 600 vals = getBasicVals().consVals(V, vals); 601 } 602 603 B.generateNode(IE, Pred, 604 state->BindExpr(IE, LCtx, 605 svalBuilder.makeCompoundVal(T, vals))); 606 return; 607 } 608 609 // Handle scalars: int{5} and int{}. 610 assert(NumInitElements <= 1); 611 612 SVal V; 613 if (NumInitElements == 0) 614 V = getSValBuilder().makeZeroVal(T); 615 else 616 V = state->getSVal(IE->getInit(0), LCtx); 617 618 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 619} 620 621void ExprEngine::VisitGuardedExpr(const Expr *Ex, 622 const Expr *L, 623 const Expr *R, 624 ExplodedNode *Pred, 625 ExplodedNodeSet &Dst) { 626 assert(L && R); 627 628 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 629 ProgramStateRef state = Pred->getState(); 630 const LocationContext *LCtx = Pred->getLocationContext(); 631 const CFGBlock *SrcBlock = 0; 632 633 // Find the predecessor block. 634 ProgramStateRef SrcState = state; 635 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { 636 ProgramPoint PP = N->getLocation(); 637 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) { 638 assert(N->pred_size() == 1); 639 continue; 640 } 641 SrcBlock = PP.castAs<BlockEdge>().getSrc(); 642 SrcState = N->getState(); 643 break; 644 } 645 646 assert(SrcBlock && "missing function entry"); 647 648 // Find the last expression in the predecessor block. That is the 649 // expression that is used for the value of the ternary expression. 650 bool hasValue = false; 651 SVal V; 652 653 for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), 654 E = SrcBlock->rend(); I != E; ++I) { 655 CFGElement CE = *I; 656 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) { 657 const Expr *ValEx = cast<Expr>(CS->getStmt()); 658 ValEx = ValEx->IgnoreParens(); 659 660 // For GNU extension '?:' operator, the left hand side will be an 661 // OpaqueValueExpr, so get the underlying expression. 662 if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L)) 663 L = OpaqueEx->getSourceExpr(); 664 665 // If the last expression in the predecessor block matches true or false 666 // subexpression, get its the value. 667 if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) { 668 hasValue = true; 669 V = SrcState->getSVal(ValEx, LCtx); 670 } 671 break; 672 } 673 } 674 675 if (!hasValue) 676 V = svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 677 678 // Generate a new node with the binding from the appropriate path. 679 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); 680} 681 682void ExprEngine:: 683VisitOffsetOfExpr(const OffsetOfExpr *OOE, 684 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 685 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 686 APSInt IV; 687 if (OOE->EvaluateAsInt(IV, getContext())) { 688 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 689 assert(OOE->getType()->isBuiltinType()); 690 assert(OOE->getType()->getAs<BuiltinType>()->isInteger()); 691 assert(IV.isSigned() == OOE->getType()->isSignedIntegerType()); 692 SVal X = svalBuilder.makeIntVal(IV); 693 B.generateNode(OOE, Pred, 694 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 695 X)); 696 } 697 // FIXME: Handle the case where __builtin_offsetof is not a constant. 698} 699 700 701void ExprEngine:: 702VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 703 ExplodedNode *Pred, 704 ExplodedNodeSet &Dst) { 705 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 706 707 QualType T = Ex->getTypeOfArgument(); 708 709 if (Ex->getKind() == UETT_SizeOf) { 710 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 711 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 712 713 // FIXME: Add support for VLA type arguments and VLA expressions. 714 // When that happens, we should probably refactor VLASizeChecker's code. 715 return; 716 } 717 else if (T->getAs<ObjCObjectType>()) { 718 // Some code tries to take the sizeof an ObjCObjectType, relying that 719 // the compiler has laid out its representation. Just report Unknown 720 // for these. 721 return; 722 } 723 } 724 725 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 726 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 727 728 ProgramStateRef state = Pred->getState(); 729 state = state->BindExpr(Ex, Pred->getLocationContext(), 730 svalBuilder.makeIntVal(amt.getQuantity(), 731 Ex->getType())); 732 Bldr.generateNode(Ex, Pred, state); 733} 734 735void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 736 ExplodedNode *Pred, 737 ExplodedNodeSet &Dst) { 738 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 739 switch (U->getOpcode()) { 740 default: { 741 Bldr.takeNodes(Pred); 742 ExplodedNodeSet Tmp; 743 VisitIncrementDecrementOperator(U, Pred, Tmp); 744 Bldr.addNodes(Tmp); 745 } 746 break; 747 case UO_Real: { 748 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 749 750 // FIXME: We don't have complex SValues yet. 751 if (Ex->getType()->isAnyComplexType()) { 752 // Just report "Unknown." 753 break; 754 } 755 756 // For all other types, UO_Real is an identity operation. 757 assert (U->getType() == Ex->getType()); 758 ProgramStateRef state = Pred->getState(); 759 const LocationContext *LCtx = Pred->getLocationContext(); 760 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 761 state->getSVal(Ex, LCtx))); 762 break; 763 } 764 765 case UO_Imag: { 766 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 767 // FIXME: We don't have complex SValues yet. 768 if (Ex->getType()->isAnyComplexType()) { 769 // Just report "Unknown." 770 break; 771 } 772 // For all other types, UO_Imag returns 0. 773 ProgramStateRef state = Pred->getState(); 774 const LocationContext *LCtx = Pred->getLocationContext(); 775 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 776 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, X)); 777 break; 778 } 779 780 case UO_Plus: 781 assert(!U->isGLValue()); 782 // FALL-THROUGH. 783 case UO_Deref: 784 case UO_AddrOf: 785 case UO_Extension: { 786 // FIXME: We can probably just have some magic in Environment::getSVal() 787 // that propagates values, instead of creating a new node here. 788 // 789 // Unary "+" is a no-op, similar to a parentheses. We still have places 790 // where it may be a block-level expression, so we need to 791 // generate an extra node that just propagates the value of the 792 // subexpression. 793 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 794 ProgramStateRef state = Pred->getState(); 795 const LocationContext *LCtx = Pred->getLocationContext(); 796 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 797 state->getSVal(Ex, LCtx))); 798 break; 799 } 800 801 case UO_LNot: 802 case UO_Minus: 803 case UO_Not: { 804 assert (!U->isGLValue()); 805 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 806 ProgramStateRef state = Pred->getState(); 807 const LocationContext *LCtx = Pred->getLocationContext(); 808 809 // Get the value of the subexpression. 810 SVal V = state->getSVal(Ex, LCtx); 811 812 if (V.isUnknownOrUndef()) { 813 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, V)); 814 break; 815 } 816 817 switch (U->getOpcode()) { 818 default: 819 llvm_unreachable("Invalid Opcode."); 820 case UO_Not: 821 // FIXME: Do we need to handle promotions? 822 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>())); 823 break; 824 case UO_Minus: 825 // FIXME: Do we need to handle promotions? 826 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>())); 827 break; 828 case UO_LNot: 829 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 830 // 831 // Note: technically we do "E == 0", but this is the same in the 832 // transfer functions as "0 == E". 833 SVal Result; 834 if (Optional<Loc> LV = V.getAs<Loc>()) { 835 Loc X = svalBuilder.makeNull(); 836 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType()); 837 } 838 else if (Ex->getType()->isFloatingType()) { 839 // FIXME: handle floating point types. 840 Result = UnknownVal(); 841 } else { 842 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 843 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X, 844 U->getType()); 845 } 846 847 state = state->BindExpr(U, LCtx, Result); 848 break; 849 } 850 Bldr.generateNode(U, Pred, state); 851 break; 852 } 853 } 854 855} 856 857void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 858 ExplodedNode *Pred, 859 ExplodedNodeSet &Dst) { 860 // Handle ++ and -- (both pre- and post-increment). 861 assert (U->isIncrementDecrementOp()); 862 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 863 864 const LocationContext *LCtx = Pred->getLocationContext(); 865 ProgramStateRef state = Pred->getState(); 866 SVal loc = state->getSVal(Ex, LCtx); 867 868 // Perform a load. 869 ExplodedNodeSet Tmp; 870 evalLoad(Tmp, U, Ex, Pred, state, loc); 871 872 ExplodedNodeSet Dst2; 873 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx); 874 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 875 876 state = (*I)->getState(); 877 assert(LCtx == (*I)->getLocationContext()); 878 SVal V2_untested = state->getSVal(Ex, LCtx); 879 880 // Propagate unknown and undefined values. 881 if (V2_untested.isUnknownOrUndef()) { 882 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 883 continue; 884 } 885 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>(); 886 887 // Handle all other values. 888 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 889 890 // If the UnaryOperator has non-location type, use its type to create the 891 // constant value. If the UnaryOperator has location type, create the 892 // constant with int type and pointer width. 893 SVal RHS; 894 895 if (U->getType()->isAnyPointerType()) 896 RHS = svalBuilder.makeArrayIndex(1); 897 else if (U->getType()->isIntegralOrEnumerationType()) 898 RHS = svalBuilder.makeIntVal(1, U->getType()); 899 else 900 RHS = UnknownVal(); 901 902 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 903 904 // Conjure a new symbol if necessary to recover precision. 905 if (Result.isUnknown()){ 906 DefinedOrUnknownSVal SymVal = 907 svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 908 Result = SymVal; 909 910 // If the value is a location, ++/-- should always preserve 911 // non-nullness. Check if the original value was non-null, and if so 912 // propagate that constraint. 913 if (Loc::isLocType(U->getType())) { 914 DefinedOrUnknownSVal Constraint = 915 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 916 917 if (!state->assume(Constraint, true)) { 918 // It isn't feasible for the original value to be null. 919 // Propagate this constraint. 920 Constraint = svalBuilder.evalEQ(state, SymVal, 921 svalBuilder.makeZeroVal(U->getType())); 922 923 924 state = state->assume(Constraint, false); 925 assert(state); 926 } 927 } 928 } 929 930 // Since the lvalue-to-rvalue conversion is explicit in the AST, 931 // we bind an l-value if the operator is prefix and an lvalue (in C++). 932 if (U->isGLValue()) 933 state = state->BindExpr(U, LCtx, loc); 934 else 935 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 936 937 // Perform the store. 938 Bldr.takeNodes(*I); 939 ExplodedNodeSet Dst3; 940 evalStore(Dst3, U, U, *I, state, loc, Result); 941 Bldr.addNodes(Dst3); 942 } 943 Dst.insert(Dst2); 944} 945