ExprEngineC.cpp revision a5796f87229b4aeebca71fa6ee1790ae7a5a0382
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 // Delegate to SValBuilder to process. 314 SVal V = state->getSVal(Ex, LCtx); 315 V = svalBuilder.evalCast(V, T, ExTy); 316 state = state->BindExpr(CastE, LCtx, V); 317 Bldr.generateNode(CastE, Pred, state); 318 continue; 319 } 320 case CK_DerivedToBase: 321 case CK_UncheckedDerivedToBase: { 322 // For DerivedToBase cast, delegate to the store manager. 323 SVal val = state->getSVal(Ex, LCtx); 324 val = getStoreManager().evalDerivedToBase(val, CastE); 325 state = state->BindExpr(CastE, LCtx, val); 326 Bldr.generateNode(CastE, Pred, state); 327 continue; 328 } 329 // Handle C++ dyn_cast. 330 case CK_Dynamic: { 331 SVal val = state->getSVal(Ex, LCtx); 332 333 // Compute the type of the result. 334 QualType resultType = CastE->getType(); 335 if (CastE->isGLValue()) 336 resultType = getContext().getPointerType(resultType); 337 338 bool Failed = false; 339 340 // Check if the value being cast evaluates to 0. 341 if (val.isZeroConstant()) 342 Failed = true; 343 // Else, evaluate the cast. 344 else 345 val = getStoreManager().evalDynamicCast(val, T, Failed); 346 347 if (Failed) { 348 if (T->isReferenceType()) { 349 // A bad_cast exception is thrown if input value is a reference. 350 // Currently, we model this, by generating a sink. 351 Bldr.generateSink(CastE, Pred, state); 352 continue; 353 } else { 354 // If the cast fails on a pointer, bind to 0. 355 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 356 } 357 } else { 358 // If we don't know if the cast succeeded, conjure a new symbol. 359 if (val.isUnknown()) { 360 DefinedOrUnknownSVal NewSym = 361 svalBuilder.conjureSymbolVal(0, CastE, LCtx, resultType, 362 currBldrCtx->blockCount()); 363 state = state->BindExpr(CastE, LCtx, NewSym); 364 } else 365 // Else, bind to the derived region value. 366 state = state->BindExpr(CastE, LCtx, val); 367 } 368 Bldr.generateNode(CastE, Pred, state); 369 continue; 370 } 371 case CK_NullToMemberPointer: { 372 // FIXME: For now, member pointers are represented by void *. 373 SVal V = svalBuilder.makeIntValWithPtrWidth(0, true); 374 state = state->BindExpr(CastE, LCtx, V); 375 Bldr.generateNode(CastE, Pred, state); 376 continue; 377 } 378 // Various C++ casts that are not handled yet. 379 case CK_ToUnion: 380 case CK_BaseToDerived: 381 case CK_BaseToDerivedMemberPointer: 382 case CK_DerivedToBaseMemberPointer: 383 case CK_ReinterpretMemberPointer: 384 case CK_VectorSplat: 385 case CK_LValueBitCast: { 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 const InitListExpr *ILE 407 = cast<InitListExpr>(CL->getInitializer()->IgnoreParens()); 408 409 ProgramStateRef state = Pred->getState(); 410 SVal ILV = state->getSVal(ILE, Pred->getLocationContext()); 411 const LocationContext *LC = Pred->getLocationContext(); 412 state = state->bindCompoundLiteral(CL, LC, ILV); 413 414 // Compound literal expressions are a GNU extension in C++. 415 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, 416 // and like temporary objects created by the functional notation T() 417 // CLs are destroyed at the end of the containing full-expression. 418 // HOWEVER, an rvalue of array type is not something the analyzer can 419 // reason about, since we expect all regions to be wrapped in Locs. 420 // So we treat array CLs as lvalues as well, knowing that they will decay 421 // to pointers as soon as they are used. 422 if (CL->isGLValue() || CL->getType()->isArrayType()) 423 B.generateNode(CL, Pred, state->BindExpr(CL, LC, state->getLValue(CL, LC))); 424 else 425 B.generateNode(CL, Pred, state->BindExpr(CL, LC, ILV)); 426} 427 428void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 429 ExplodedNodeSet &Dst) { 430 // Assumption: The CFG has one DeclStmt per Decl. 431 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin()); 432 433 if (!VD) { 434 //TODO:AZ: remove explicit insertion after refactoring is done. 435 Dst.insert(Pred); 436 return; 437 } 438 439 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 440 ExplodedNodeSet dstPreVisit; 441 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 442 443 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 444 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 445 I!=E; ++I) { 446 ExplodedNode *N = *I; 447 ProgramStateRef state = N->getState(); 448 const LocationContext *LC = N->getLocationContext(); 449 450 // Decls without InitExpr are not initialized explicitly. 451 if (const Expr *InitEx = VD->getInit()) { 452 453 // Note in the state that the initialization has occurred. 454 ExplodedNode *UpdatedN = N; 455 SVal InitVal = state->getSVal(InitEx, LC); 456 457 if (isa<CXXConstructExpr>(InitEx->IgnoreImplicit())) { 458 // We constructed the object directly in the variable. 459 // No need to bind anything. 460 B.generateNode(DS, UpdatedN, state); 461 } else { 462 // We bound the temp obj region to the CXXConstructExpr. Now recover 463 // the lazy compound value when the variable is not a reference. 464 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 465 !VD->getType()->isReferenceType()) { 466 if (Optional<loc::MemRegionVal> M = 467 InitVal.getAs<loc::MemRegionVal>()) { 468 InitVal = state->getSVal(M->getRegion()); 469 assert(InitVal.getAs<nonloc::LazyCompoundVal>()); 470 } 471 } 472 473 // Recover some path-sensitivity if a scalar value evaluated to 474 // UnknownVal. 475 if (InitVal.isUnknown()) { 476 QualType Ty = InitEx->getType(); 477 if (InitEx->isGLValue()) { 478 Ty = getContext().getPointerType(Ty); 479 } 480 481 InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, 482 currBldrCtx->blockCount()); 483 } 484 485 486 B.takeNodes(UpdatedN); 487 ExplodedNodeSet Dst2; 488 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true); 489 B.addNodes(Dst2); 490 } 491 } 492 else { 493 B.generateNode(DS, N, state); 494 } 495 } 496} 497 498void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 499 ExplodedNodeSet &Dst) { 500 assert(B->getOpcode() == BO_LAnd || 501 B->getOpcode() == BO_LOr); 502 503 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 504 ProgramStateRef state = Pred->getState(); 505 506 ExplodedNode *N = Pred; 507 while (!N->getLocation().getAs<BlockEntrance>()) { 508 ProgramPoint P = N->getLocation(); 509 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>()); 510 (void) P; 511 assert(N->pred_size() == 1); 512 N = *N->pred_begin(); 513 } 514 assert(N->pred_size() == 1); 515 N = *N->pred_begin(); 516 BlockEdge BE = N->getLocation().castAs<BlockEdge>(); 517 SVal X; 518 519 // Determine the value of the expression by introspecting how we 520 // got this location in the CFG. This requires looking at the previous 521 // block we were in and what kind of control-flow transfer was involved. 522 const CFGBlock *SrcBlock = BE.getSrc(); 523 // The only terminator (if there is one) that makes sense is a logical op. 524 CFGTerminator T = SrcBlock->getTerminator(); 525 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { 526 (void) Term; 527 assert(Term->isLogicalOp()); 528 assert(SrcBlock->succ_size() == 2); 529 // Did we take the true or false branch? 530 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; 531 X = svalBuilder.makeIntVal(constant, B->getType()); 532 } 533 else { 534 // If there is no terminator, by construction the last statement 535 // in SrcBlock is the value of the enclosing expression. 536 // However, we still need to constrain that value to be 0 or 1. 537 assert(!SrcBlock->empty()); 538 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>(); 539 const Expr *RHS = cast<Expr>(Elem.getStmt()); 540 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); 541 542 if (RHSVal.isUndef()) { 543 X = RHSVal; 544 } else { 545 DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>(); 546 ProgramStateRef StTrue, StFalse; 547 llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); 548 if (StTrue) { 549 if (StFalse) { 550 // We can't constrain the value to 0 or 1. 551 // The best we can do is a cast. 552 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); 553 } else { 554 // The value is known to be true. 555 X = getSValBuilder().makeIntVal(1, B->getType()); 556 } 557 } else { 558 // The value is known to be false. 559 assert(StFalse && "Infeasible path!"); 560 X = getSValBuilder().makeIntVal(0, B->getType()); 561 } 562 } 563 } 564 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); 565} 566 567void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 568 ExplodedNode *Pred, 569 ExplodedNodeSet &Dst) { 570 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 571 572 ProgramStateRef state = Pred->getState(); 573 const LocationContext *LCtx = Pred->getLocationContext(); 574 QualType T = getContext().getCanonicalType(IE->getType()); 575 unsigned NumInitElements = IE->getNumInits(); 576 577 if (T->isArrayType() || T->isRecordType() || T->isVectorType() || 578 T->isAnyComplexType()) { 579 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 580 581 // Handle base case where the initializer has no elements. 582 // e.g: static int* myArray[] = {}; 583 if (NumInitElements == 0) { 584 SVal V = svalBuilder.makeCompoundVal(T, vals); 585 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 586 return; 587 } 588 589 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 590 ei = IE->rend(); it != ei; ++it) { 591 SVal V = state->getSVal(cast<Expr>(*it), LCtx); 592 if (dyn_cast_or_null<CXXTempObjectRegion>(V.getAsRegion())) 593 V = UnknownVal(); 594 vals = getBasicVals().consVals(V, vals); 595 } 596 597 B.generateNode(IE, Pred, 598 state->BindExpr(IE, LCtx, 599 svalBuilder.makeCompoundVal(T, vals))); 600 return; 601 } 602 603 // Handle scalars: int{5} and int{}. 604 assert(NumInitElements <= 1); 605 606 SVal V; 607 if (NumInitElements == 0) 608 V = getSValBuilder().makeZeroVal(T); 609 else 610 V = state->getSVal(IE->getInit(0), LCtx); 611 612 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 613} 614 615void ExprEngine::VisitGuardedExpr(const Expr *Ex, 616 const Expr *L, 617 const Expr *R, 618 ExplodedNode *Pred, 619 ExplodedNodeSet &Dst) { 620 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 621 ProgramStateRef state = Pred->getState(); 622 const LocationContext *LCtx = Pred->getLocationContext(); 623 const CFGBlock *SrcBlock = 0; 624 625 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { 626 ProgramPoint PP = N->getLocation(); 627 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) { 628 assert(N->pred_size() == 1); 629 continue; 630 } 631 SrcBlock = PP.castAs<BlockEdge>().getSrc(); 632 break; 633 } 634 635 assert(SrcBlock && "missing function entry"); 636 637 // Find the last expression in the predecessor block. That is the 638 // expression that is used for the value of the ternary expression. 639 bool hasValue = false; 640 SVal V; 641 642 for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), 643 E = SrcBlock->rend(); I != E; ++I) { 644 CFGElement CE = *I; 645 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) { 646 const Expr *ValEx = cast<Expr>(CS->getStmt()); 647 hasValue = true; 648 V = state->getSVal(ValEx, LCtx); 649 break; 650 } 651 } 652 653 assert(hasValue); 654 (void) hasValue; 655 656 // Generate a new node with the binding from the appropriate path. 657 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); 658} 659 660void ExprEngine:: 661VisitOffsetOfExpr(const OffsetOfExpr *OOE, 662 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 663 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 664 APSInt IV; 665 if (OOE->EvaluateAsInt(IV, getContext())) { 666 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 667 assert(OOE->getType()->isBuiltinType()); 668 assert(OOE->getType()->getAs<BuiltinType>()->isInteger()); 669 assert(IV.isSigned() == OOE->getType()->isSignedIntegerType()); 670 SVal X = svalBuilder.makeIntVal(IV); 671 B.generateNode(OOE, Pred, 672 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 673 X)); 674 } 675 // FIXME: Handle the case where __builtin_offsetof is not a constant. 676} 677 678 679void ExprEngine:: 680VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 681 ExplodedNode *Pred, 682 ExplodedNodeSet &Dst) { 683 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 684 685 QualType T = Ex->getTypeOfArgument(); 686 687 if (Ex->getKind() == UETT_SizeOf) { 688 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 689 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 690 691 // FIXME: Add support for VLA type arguments and VLA expressions. 692 // When that happens, we should probably refactor VLASizeChecker's code. 693 return; 694 } 695 else if (T->getAs<ObjCObjectType>()) { 696 // Some code tries to take the sizeof an ObjCObjectType, relying that 697 // the compiler has laid out its representation. Just report Unknown 698 // for these. 699 return; 700 } 701 } 702 703 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 704 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 705 706 ProgramStateRef state = Pred->getState(); 707 state = state->BindExpr(Ex, Pred->getLocationContext(), 708 svalBuilder.makeIntVal(amt.getQuantity(), 709 Ex->getType())); 710 Bldr.generateNode(Ex, Pred, state); 711} 712 713void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 714 ExplodedNode *Pred, 715 ExplodedNodeSet &Dst) { 716 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 717 switch (U->getOpcode()) { 718 default: { 719 Bldr.takeNodes(Pred); 720 ExplodedNodeSet Tmp; 721 VisitIncrementDecrementOperator(U, Pred, Tmp); 722 Bldr.addNodes(Tmp); 723 } 724 break; 725 case UO_Real: { 726 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 727 728 // FIXME: We don't have complex SValues yet. 729 if (Ex->getType()->isAnyComplexType()) { 730 // Just report "Unknown." 731 break; 732 } 733 734 // For all other types, UO_Real is an identity operation. 735 assert (U->getType() == Ex->getType()); 736 ProgramStateRef state = Pred->getState(); 737 const LocationContext *LCtx = Pred->getLocationContext(); 738 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 739 state->getSVal(Ex, LCtx))); 740 break; 741 } 742 743 case UO_Imag: { 744 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 745 // FIXME: We don't have complex SValues yet. 746 if (Ex->getType()->isAnyComplexType()) { 747 // Just report "Unknown." 748 break; 749 } 750 // For all other types, UO_Imag returns 0. 751 ProgramStateRef state = Pred->getState(); 752 const LocationContext *LCtx = Pred->getLocationContext(); 753 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 754 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, X)); 755 break; 756 } 757 758 case UO_Plus: 759 assert(!U->isGLValue()); 760 // FALL-THROUGH. 761 case UO_Deref: 762 case UO_AddrOf: 763 case UO_Extension: { 764 // FIXME: We can probably just have some magic in Environment::getSVal() 765 // that propagates values, instead of creating a new node here. 766 // 767 // Unary "+" is a no-op, similar to a parentheses. We still have places 768 // where it may be a block-level expression, so we need to 769 // generate an extra node that just propagates the value of the 770 // subexpression. 771 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 772 ProgramStateRef state = Pred->getState(); 773 const LocationContext *LCtx = Pred->getLocationContext(); 774 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 775 state->getSVal(Ex, LCtx))); 776 break; 777 } 778 779 case UO_LNot: 780 case UO_Minus: 781 case UO_Not: { 782 assert (!U->isGLValue()); 783 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 784 ProgramStateRef state = Pred->getState(); 785 const LocationContext *LCtx = Pred->getLocationContext(); 786 787 // Get the value of the subexpression. 788 SVal V = state->getSVal(Ex, LCtx); 789 790 if (V.isUnknownOrUndef()) { 791 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, V)); 792 break; 793 } 794 795 switch (U->getOpcode()) { 796 default: 797 llvm_unreachable("Invalid Opcode."); 798 case UO_Not: 799 // FIXME: Do we need to handle promotions? 800 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>())); 801 break; 802 case UO_Minus: 803 // FIXME: Do we need to handle promotions? 804 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>())); 805 break; 806 case UO_LNot: 807 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 808 // 809 // Note: technically we do "E == 0", but this is the same in the 810 // transfer functions as "0 == E". 811 SVal Result; 812 if (Optional<Loc> LV = V.getAs<Loc>()) { 813 Loc X = svalBuilder.makeNull(); 814 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType()); 815 } 816 else if (Ex->getType()->isFloatingType()) { 817 // FIXME: handle floating point types. 818 Result = UnknownVal(); 819 } else { 820 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 821 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X, 822 U->getType()); 823 } 824 825 state = state->BindExpr(U, LCtx, Result); 826 break; 827 } 828 Bldr.generateNode(U, Pred, state); 829 break; 830 } 831 } 832 833} 834 835void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 836 ExplodedNode *Pred, 837 ExplodedNodeSet &Dst) { 838 // Handle ++ and -- (both pre- and post-increment). 839 assert (U->isIncrementDecrementOp()); 840 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 841 842 const LocationContext *LCtx = Pred->getLocationContext(); 843 ProgramStateRef state = Pred->getState(); 844 SVal loc = state->getSVal(Ex, LCtx); 845 846 // Perform a load. 847 ExplodedNodeSet Tmp; 848 evalLoad(Tmp, U, Ex, Pred, state, loc); 849 850 ExplodedNodeSet Dst2; 851 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx); 852 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 853 854 state = (*I)->getState(); 855 assert(LCtx == (*I)->getLocationContext()); 856 SVal V2_untested = state->getSVal(Ex, LCtx); 857 858 // Propagate unknown and undefined values. 859 if (V2_untested.isUnknownOrUndef()) { 860 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 861 continue; 862 } 863 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>(); 864 865 // Handle all other values. 866 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 867 868 // If the UnaryOperator has non-location type, use its type to create the 869 // constant value. If the UnaryOperator has location type, create the 870 // constant with int type and pointer width. 871 SVal RHS; 872 873 if (U->getType()->isAnyPointerType()) 874 RHS = svalBuilder.makeArrayIndex(1); 875 else if (U->getType()->isIntegralOrEnumerationType()) 876 RHS = svalBuilder.makeIntVal(1, U->getType()); 877 else 878 RHS = UnknownVal(); 879 880 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 881 882 // Conjure a new symbol if necessary to recover precision. 883 if (Result.isUnknown()){ 884 DefinedOrUnknownSVal SymVal = 885 svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 886 Result = SymVal; 887 888 // If the value is a location, ++/-- should always preserve 889 // non-nullness. Check if the original value was non-null, and if so 890 // propagate that constraint. 891 if (Loc::isLocType(U->getType())) { 892 DefinedOrUnknownSVal Constraint = 893 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 894 895 if (!state->assume(Constraint, true)) { 896 // It isn't feasible for the original value to be null. 897 // Propagate this constraint. 898 Constraint = svalBuilder.evalEQ(state, SymVal, 899 svalBuilder.makeZeroVal(U->getType())); 900 901 902 state = state->assume(Constraint, false); 903 assert(state); 904 } 905 } 906 } 907 908 // Since the lvalue-to-rvalue conversion is explicit in the AST, 909 // we bind an l-value if the operator is prefix and an lvalue (in C++). 910 if (U->isGLValue()) 911 state = state->BindExpr(U, LCtx, loc); 912 else 913 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 914 915 // Perform the store. 916 Bldr.takeNodes(*I); 917 ExplodedNodeSet Dst3; 918 evalStore(Dst3, U, U, *I, state, loc, Result); 919 Bldr.addNodes(Dst3); 920 } 921 Dst.insert(Dst2); 922} 923