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 currBldrCtx->blockCount()); 189 190 ProgramStateRef State = Pred->getState(); 191 192 // If we created a new MemRegion for the block, we should explicitly bind 193 // the captured variables. 194 if (const BlockDataRegion *BDR = 195 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) { 196 197 BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(), 198 E = BDR->referenced_vars_end(); 199 200 for (; I != E; ++I) { 201 const MemRegion *capturedR = I.getCapturedRegion(); 202 const MemRegion *originalR = I.getOriginalRegion(); 203 if (capturedR != originalR) { 204 SVal originalV = State->getSVal(loc::MemRegionVal(originalR)); 205 State = State->bindLoc(loc::MemRegionVal(capturedR), originalV); 206 } 207 } 208 } 209 210 ExplodedNodeSet Tmp; 211 StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx); 212 Bldr.generateNode(BE, Pred, 213 State->BindExpr(BE, Pred->getLocationContext(), V), 214 0, ProgramPoint::PostLValueKind); 215 216 // FIXME: Move all post/pre visits to ::Visit(). 217 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this); 218} 219 220void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, 221 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 222 223 ExplodedNodeSet dstPreStmt; 224 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this); 225 226 if (CastE->getCastKind() == CK_LValueToRValue) { 227 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 228 I!=E; ++I) { 229 ExplodedNode *subExprNode = *I; 230 ProgramStateRef state = subExprNode->getState(); 231 const LocationContext *LCtx = subExprNode->getLocationContext(); 232 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx)); 233 } 234 return; 235 } 236 237 // All other casts. 238 QualType T = CastE->getType(); 239 QualType ExTy = Ex->getType(); 240 241 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE)) 242 T = ExCast->getTypeAsWritten(); 243 244 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx); 245 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 246 I != E; ++I) { 247 248 Pred = *I; 249 ProgramStateRef state = Pred->getState(); 250 const LocationContext *LCtx = Pred->getLocationContext(); 251 252 switch (CastE->getCastKind()) { 253 case CK_LValueToRValue: 254 llvm_unreachable("LValueToRValue casts handled earlier."); 255 case CK_ToVoid: 256 continue; 257 // The analyzer doesn't do anything special with these casts, 258 // since it understands retain/release semantics already. 259 case CK_ARCProduceObject: 260 case CK_ARCConsumeObject: 261 case CK_ARCReclaimReturnedObject: 262 case CK_ARCExtendBlockObject: // Fall-through. 263 case CK_CopyAndAutoreleaseBlockObject: 264 // The analyser can ignore atomic casts for now, although some future 265 // checkers may want to make certain that you're not modifying the same 266 // value through atomic and nonatomic pointers. 267 case CK_AtomicToNonAtomic: 268 case CK_NonAtomicToAtomic: 269 // True no-ops. 270 case CK_NoOp: 271 case CK_ConstructorConversion: 272 case CK_UserDefinedConversion: 273 case CK_FunctionToPointerDecay: 274 case CK_BuiltinFnToFnPtr: { 275 // Copy the SVal of Ex to CastE. 276 ProgramStateRef state = Pred->getState(); 277 const LocationContext *LCtx = Pred->getLocationContext(); 278 SVal V = state->getSVal(Ex, LCtx); 279 state = state->BindExpr(CastE, LCtx, V); 280 Bldr.generateNode(CastE, Pred, state); 281 continue; 282 } 283 case CK_MemberPointerToBoolean: 284 // FIXME: For now, member pointers are represented by void *. 285 // FALLTHROUGH 286 case CK_Dependent: 287 case CK_ArrayToPointerDecay: 288 case CK_BitCast: 289 case CK_IntegralCast: 290 case CK_NullToPointer: 291 case CK_IntegralToPointer: 292 case CK_PointerToIntegral: 293 case CK_PointerToBoolean: 294 case CK_IntegralToBoolean: 295 case CK_IntegralToFloating: 296 case CK_FloatingToIntegral: 297 case CK_FloatingToBoolean: 298 case CK_FloatingCast: 299 case CK_FloatingRealToComplex: 300 case CK_FloatingComplexToReal: 301 case CK_FloatingComplexToBoolean: 302 case CK_FloatingComplexCast: 303 case CK_FloatingComplexToIntegralComplex: 304 case CK_IntegralRealToComplex: 305 case CK_IntegralComplexToReal: 306 case CK_IntegralComplexToBoolean: 307 case CK_IntegralComplexCast: 308 case CK_IntegralComplexToFloatingComplex: 309 case CK_CPointerToObjCPointerCast: 310 case CK_BlockPointerToObjCPointerCast: 311 case CK_AnyPointerToBlockPointerCast: 312 case CK_ObjCObjectLValueCast: 313 case CK_ZeroToOCLEvent: 314 case CK_LValueBitCast: { 315 // Delegate to SValBuilder to process. 316 SVal V = state->getSVal(Ex, LCtx); 317 V = svalBuilder.evalCast(V, T, ExTy); 318 state = state->BindExpr(CastE, LCtx, V); 319 Bldr.generateNode(CastE, Pred, state); 320 continue; 321 } 322 case CK_DerivedToBase: 323 case CK_UncheckedDerivedToBase: { 324 // For DerivedToBase cast, delegate to the store manager. 325 SVal val = state->getSVal(Ex, LCtx); 326 val = getStoreManager().evalDerivedToBase(val, CastE); 327 state = state->BindExpr(CastE, LCtx, val); 328 Bldr.generateNode(CastE, Pred, state); 329 continue; 330 } 331 // Handle C++ dyn_cast. 332 case CK_Dynamic: { 333 SVal val = state->getSVal(Ex, LCtx); 334 335 // Compute the type of the result. 336 QualType resultType = CastE->getType(); 337 if (CastE->isGLValue()) 338 resultType = getContext().getPointerType(resultType); 339 340 bool Failed = false; 341 342 // Check if the value being cast evaluates to 0. 343 if (val.isZeroConstant()) 344 Failed = true; 345 // Else, evaluate the cast. 346 else 347 val = getStoreManager().evalDynamicCast(val, T, Failed); 348 349 if (Failed) { 350 if (T->isReferenceType()) { 351 // A bad_cast exception is thrown if input value is a reference. 352 // Currently, we model this, by generating a sink. 353 Bldr.generateSink(CastE, Pred, state); 354 continue; 355 } else { 356 // If the cast fails on a pointer, bind to 0. 357 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 358 } 359 } else { 360 // If we don't know if the cast succeeded, conjure a new symbol. 361 if (val.isUnknown()) { 362 DefinedOrUnknownSVal NewSym = 363 svalBuilder.conjureSymbolVal(0, CastE, LCtx, resultType, 364 currBldrCtx->blockCount()); 365 state = state->BindExpr(CastE, LCtx, NewSym); 366 } else 367 // Else, bind to the derived region value. 368 state = state->BindExpr(CastE, LCtx, val); 369 } 370 Bldr.generateNode(CastE, Pred, state); 371 continue; 372 } 373 case CK_NullToMemberPointer: { 374 // FIXME: For now, member pointers are represented by void *. 375 SVal V = svalBuilder.makeNull(); 376 state = state->BindExpr(CastE, LCtx, V); 377 Bldr.generateNode(CastE, Pred, state); 378 continue; 379 } 380 // Various C++ casts that are not handled yet. 381 case CK_ToUnion: 382 case CK_BaseToDerived: 383 case CK_BaseToDerivedMemberPointer: 384 case CK_DerivedToBaseMemberPointer: 385 case CK_ReinterpretMemberPointer: 386 case CK_VectorSplat: { 387 // Recover some path-sensitivty by conjuring a new value. 388 QualType resultType = CastE->getType(); 389 if (CastE->isGLValue()) 390 resultType = getContext().getPointerType(resultType); 391 SVal result = svalBuilder.conjureSymbolVal(0, CastE, LCtx, 392 resultType, 393 currBldrCtx->blockCount()); 394 state = state->BindExpr(CastE, LCtx, result); 395 Bldr.generateNode(CastE, Pred, state); 396 continue; 397 } 398 } 399 } 400} 401 402void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 403 ExplodedNode *Pred, 404 ExplodedNodeSet &Dst) { 405 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 406 407 ProgramStateRef State = Pred->getState(); 408 const LocationContext *LCtx = Pred->getLocationContext(); 409 410 const Expr *Init = CL->getInitializer(); 411 SVal V = State->getSVal(CL->getInitializer(), LCtx); 412 413 if (isa<CXXConstructExpr>(Init)) { 414 // No work needed. Just pass the value up to this expression. 415 } else { 416 assert(isa<InitListExpr>(Init)); 417 Loc CLLoc = State->getLValue(CL, LCtx); 418 State = State->bindLoc(CLLoc, V); 419 420 // Compound literal expressions are a GNU extension in C++. 421 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, 422 // and like temporary objects created by the functional notation T() 423 // CLs are destroyed at the end of the containing full-expression. 424 // HOWEVER, an rvalue of array type is not something the analyzer can 425 // reason about, since we expect all regions to be wrapped in Locs. 426 // So we treat array CLs as lvalues as well, knowing that they will decay 427 // to pointers as soon as they are used. 428 if (CL->isGLValue() || CL->getType()->isArrayType()) 429 V = CLLoc; 430 } 431 432 B.generateNode(CL, Pred, State->BindExpr(CL, LCtx, V)); 433} 434 435void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 436 ExplodedNodeSet &Dst) { 437 // Assumption: The CFG has one DeclStmt per Decl. 438 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin()); 439 440 if (!VD) { 441 //TODO:AZ: remove explicit insertion after refactoring is done. 442 Dst.insert(Pred); 443 return; 444 } 445 446 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 447 ExplodedNodeSet dstPreVisit; 448 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 449 450 ExplodedNodeSet dstEvaluated; 451 StmtNodeBuilder B(dstPreVisit, dstEvaluated, *currBldrCtx); 452 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 453 I!=E; ++I) { 454 ExplodedNode *N = *I; 455 ProgramStateRef state = N->getState(); 456 const LocationContext *LC = N->getLocationContext(); 457 458 // Decls without InitExpr are not initialized explicitly. 459 if (const Expr *InitEx = VD->getInit()) { 460 461 // Note in the state that the initialization has occurred. 462 ExplodedNode *UpdatedN = N; 463 SVal InitVal = state->getSVal(InitEx, LC); 464 465 if (isa<CXXConstructExpr>(InitEx->IgnoreImplicit())) { 466 // We constructed the object directly in the variable. 467 // No need to bind anything. 468 B.generateNode(DS, UpdatedN, state); 469 } else { 470 // We bound the temp obj region to the CXXConstructExpr. Now recover 471 // the lazy compound value when the variable is not a reference. 472 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 473 !VD->getType()->isReferenceType()) { 474 if (Optional<loc::MemRegionVal> M = 475 InitVal.getAs<loc::MemRegionVal>()) { 476 InitVal = state->getSVal(M->getRegion()); 477 assert(InitVal.getAs<nonloc::LazyCompoundVal>()); 478 } 479 } 480 481 // Recover some path-sensitivity if a scalar value evaluated to 482 // UnknownVal. 483 if (InitVal.isUnknown()) { 484 QualType Ty = InitEx->getType(); 485 if (InitEx->isGLValue()) { 486 Ty = getContext().getPointerType(Ty); 487 } 488 489 InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, 490 currBldrCtx->blockCount()); 491 } 492 493 494 B.takeNodes(UpdatedN); 495 ExplodedNodeSet Dst2; 496 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true); 497 B.addNodes(Dst2); 498 } 499 } 500 else { 501 B.generateNode(DS, N, state); 502 } 503 } 504 505 getCheckerManager().runCheckersForPostStmt(Dst, B.getResults(), DS, *this); 506} 507 508void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 509 ExplodedNodeSet &Dst) { 510 assert(B->getOpcode() == BO_LAnd || 511 B->getOpcode() == BO_LOr); 512 513 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 514 ProgramStateRef state = Pred->getState(); 515 516 ExplodedNode *N = Pred; 517 while (!N->getLocation().getAs<BlockEntrance>()) { 518 ProgramPoint P = N->getLocation(); 519 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>()); 520 (void) P; 521 assert(N->pred_size() == 1); 522 N = *N->pred_begin(); 523 } 524 assert(N->pred_size() == 1); 525 N = *N->pred_begin(); 526 BlockEdge BE = N->getLocation().castAs<BlockEdge>(); 527 SVal X; 528 529 // Determine the value of the expression by introspecting how we 530 // got this location in the CFG. This requires looking at the previous 531 // block we were in and what kind of control-flow transfer was involved. 532 const CFGBlock *SrcBlock = BE.getSrc(); 533 // The only terminator (if there is one) that makes sense is a logical op. 534 CFGTerminator T = SrcBlock->getTerminator(); 535 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { 536 (void) Term; 537 assert(Term->isLogicalOp()); 538 assert(SrcBlock->succ_size() == 2); 539 // Did we take the true or false branch? 540 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; 541 X = svalBuilder.makeIntVal(constant, B->getType()); 542 } 543 else { 544 // If there is no terminator, by construction the last statement 545 // in SrcBlock is the value of the enclosing expression. 546 // However, we still need to constrain that value to be 0 or 1. 547 assert(!SrcBlock->empty()); 548 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>(); 549 const Expr *RHS = cast<Expr>(Elem.getStmt()); 550 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); 551 552 if (RHSVal.isUndef()) { 553 X = RHSVal; 554 } else { 555 DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>(); 556 ProgramStateRef StTrue, StFalse; 557 llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); 558 if (StTrue) { 559 if (StFalse) { 560 // We can't constrain the value to 0 or 1. 561 // The best we can do is a cast. 562 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); 563 } else { 564 // The value is known to be true. 565 X = getSValBuilder().makeIntVal(1, B->getType()); 566 } 567 } else { 568 // The value is known to be false. 569 assert(StFalse && "Infeasible path!"); 570 X = getSValBuilder().makeIntVal(0, B->getType()); 571 } 572 } 573 } 574 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); 575} 576 577void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 578 ExplodedNode *Pred, 579 ExplodedNodeSet &Dst) { 580 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 581 582 ProgramStateRef state = Pred->getState(); 583 const LocationContext *LCtx = Pred->getLocationContext(); 584 QualType T = getContext().getCanonicalType(IE->getType()); 585 unsigned NumInitElements = IE->getNumInits(); 586 587 if (!IE->isGLValue() && 588 (T->isArrayType() || T->isRecordType() || T->isVectorType() || 589 T->isAnyComplexType())) { 590 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 591 592 // Handle base case where the initializer has no elements. 593 // e.g: static int* myArray[] = {}; 594 if (NumInitElements == 0) { 595 SVal V = svalBuilder.makeCompoundVal(T, vals); 596 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 597 return; 598 } 599 600 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 601 ei = IE->rend(); it != ei; ++it) { 602 SVal V = state->getSVal(cast<Expr>(*it), LCtx); 603 vals = getBasicVals().consVals(V, vals); 604 } 605 606 B.generateNode(IE, Pred, 607 state->BindExpr(IE, LCtx, 608 svalBuilder.makeCompoundVal(T, vals))); 609 return; 610 } 611 612 // Handle scalars: int{5} and int{} and GLvalues. 613 // Note, if the InitListExpr is a GLvalue, it means that there is an address 614 // representing it, so it must have a single init element. 615 assert(NumInitElements <= 1); 616 617 SVal V; 618 if (NumInitElements == 0) 619 V = getSValBuilder().makeZeroVal(T); 620 else 621 V = state->getSVal(IE->getInit(0), LCtx); 622 623 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 624} 625 626void ExprEngine::VisitGuardedExpr(const Expr *Ex, 627 const Expr *L, 628 const Expr *R, 629 ExplodedNode *Pred, 630 ExplodedNodeSet &Dst) { 631 assert(L && R); 632 633 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 634 ProgramStateRef state = Pred->getState(); 635 const LocationContext *LCtx = Pred->getLocationContext(); 636 const CFGBlock *SrcBlock = 0; 637 638 // Find the predecessor block. 639 ProgramStateRef SrcState = state; 640 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { 641 ProgramPoint PP = N->getLocation(); 642 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) { 643 assert(N->pred_size() == 1); 644 continue; 645 } 646 SrcBlock = PP.castAs<BlockEdge>().getSrc(); 647 SrcState = N->getState(); 648 break; 649 } 650 651 assert(SrcBlock && "missing function entry"); 652 653 // Find the last expression in the predecessor block. That is the 654 // expression that is used for the value of the ternary expression. 655 bool hasValue = false; 656 SVal V; 657 658 for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), 659 E = SrcBlock->rend(); I != E; ++I) { 660 CFGElement CE = *I; 661 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) { 662 const Expr *ValEx = cast<Expr>(CS->getStmt()); 663 ValEx = ValEx->IgnoreParens(); 664 665 // For GNU extension '?:' operator, the left hand side will be an 666 // OpaqueValueExpr, so get the underlying expression. 667 if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L)) 668 L = OpaqueEx->getSourceExpr(); 669 670 // If the last expression in the predecessor block matches true or false 671 // subexpression, get its the value. 672 if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) { 673 hasValue = true; 674 V = SrcState->getSVal(ValEx, LCtx); 675 } 676 break; 677 } 678 } 679 680 if (!hasValue) 681 V = svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 682 683 // Generate a new node with the binding from the appropriate path. 684 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); 685} 686 687void ExprEngine:: 688VisitOffsetOfExpr(const OffsetOfExpr *OOE, 689 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 690 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 691 APSInt IV; 692 if (OOE->EvaluateAsInt(IV, getContext())) { 693 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 694 assert(OOE->getType()->isBuiltinType()); 695 assert(OOE->getType()->getAs<BuiltinType>()->isInteger()); 696 assert(IV.isSigned() == OOE->getType()->isSignedIntegerType()); 697 SVal X = svalBuilder.makeIntVal(IV); 698 B.generateNode(OOE, Pred, 699 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 700 X)); 701 } 702 // FIXME: Handle the case where __builtin_offsetof is not a constant. 703} 704 705 706void ExprEngine:: 707VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 708 ExplodedNode *Pred, 709 ExplodedNodeSet &Dst) { 710 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 711 712 QualType T = Ex->getTypeOfArgument(); 713 714 if (Ex->getKind() == UETT_SizeOf) { 715 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 716 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 717 718 // FIXME: Add support for VLA type arguments and VLA expressions. 719 // When that happens, we should probably refactor VLASizeChecker's code. 720 return; 721 } 722 else if (T->getAs<ObjCObjectType>()) { 723 // Some code tries to take the sizeof an ObjCObjectType, relying that 724 // the compiler has laid out its representation. Just report Unknown 725 // for these. 726 return; 727 } 728 } 729 730 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 731 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 732 733 ProgramStateRef state = Pred->getState(); 734 state = state->BindExpr(Ex, Pred->getLocationContext(), 735 svalBuilder.makeIntVal(amt.getQuantity(), 736 Ex->getType())); 737 Bldr.generateNode(Ex, Pred, state); 738} 739 740void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 741 ExplodedNode *Pred, 742 ExplodedNodeSet &Dst) { 743 // FIXME: Prechecks eventually go in ::Visit(). 744 ExplodedNodeSet CheckedSet; 745 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, U, *this); 746 747 ExplodedNodeSet EvalSet; 748 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx); 749 750 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end(); 751 I != E; ++I) { 752 switch (U->getOpcode()) { 753 default: { 754 Bldr.takeNodes(*I); 755 ExplodedNodeSet Tmp; 756 VisitIncrementDecrementOperator(U, *I, Tmp); 757 Bldr.addNodes(Tmp); 758 break; 759 } 760 case UO_Real: { 761 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 762 763 // FIXME: We don't have complex SValues yet. 764 if (Ex->getType()->isAnyComplexType()) { 765 // Just report "Unknown." 766 break; 767 } 768 769 // For all other types, UO_Real is an identity operation. 770 assert (U->getType() == Ex->getType()); 771 ProgramStateRef state = (*I)->getState(); 772 const LocationContext *LCtx = (*I)->getLocationContext(); 773 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, 774 state->getSVal(Ex, LCtx))); 775 break; 776 } 777 778 case UO_Imag: { 779 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 780 // FIXME: We don't have complex SValues yet. 781 if (Ex->getType()->isAnyComplexType()) { 782 // Just report "Unknown." 783 break; 784 } 785 // For all other types, UO_Imag returns 0. 786 ProgramStateRef state = (*I)->getState(); 787 const LocationContext *LCtx = (*I)->getLocationContext(); 788 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 789 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, X)); 790 break; 791 } 792 793 case UO_Plus: 794 assert(!U->isGLValue()); 795 // FALL-THROUGH. 796 case UO_Deref: 797 case UO_AddrOf: 798 case UO_Extension: { 799 // FIXME: We can probably just have some magic in Environment::getSVal() 800 // that propagates values, instead of creating a new node here. 801 // 802 // Unary "+" is a no-op, similar to a parentheses. We still have places 803 // where it may be a block-level expression, so we need to 804 // generate an extra node that just propagates the value of the 805 // subexpression. 806 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 807 ProgramStateRef state = (*I)->getState(); 808 const LocationContext *LCtx = (*I)->getLocationContext(); 809 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, 810 state->getSVal(Ex, LCtx))); 811 break; 812 } 813 814 case UO_LNot: 815 case UO_Minus: 816 case UO_Not: { 817 assert (!U->isGLValue()); 818 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 819 ProgramStateRef state = (*I)->getState(); 820 const LocationContext *LCtx = (*I)->getLocationContext(); 821 822 // Get the value of the subexpression. 823 SVal V = state->getSVal(Ex, LCtx); 824 825 if (V.isUnknownOrUndef()) { 826 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V)); 827 break; 828 } 829 830 switch (U->getOpcode()) { 831 default: 832 llvm_unreachable("Invalid Opcode."); 833 case UO_Not: 834 // FIXME: Do we need to handle promotions? 835 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>())); 836 break; 837 case UO_Minus: 838 // FIXME: Do we need to handle promotions? 839 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>())); 840 break; 841 case UO_LNot: 842 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 843 // 844 // Note: technically we do "E == 0", but this is the same in the 845 // transfer functions as "0 == E". 846 SVal Result; 847 if (Optional<Loc> LV = V.getAs<Loc>()) { 848 Loc X = svalBuilder.makeNull(); 849 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType()); 850 } 851 else if (Ex->getType()->isFloatingType()) { 852 // FIXME: handle floating point types. 853 Result = UnknownVal(); 854 } else { 855 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 856 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X, 857 U->getType()); 858 } 859 860 state = state->BindExpr(U, LCtx, Result); 861 break; 862 } 863 Bldr.generateNode(U, *I, state); 864 break; 865 } 866 } 867 } 868 869 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, U, *this); 870} 871 872void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 873 ExplodedNode *Pred, 874 ExplodedNodeSet &Dst) { 875 // Handle ++ and -- (both pre- and post-increment). 876 assert (U->isIncrementDecrementOp()); 877 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 878 879 const LocationContext *LCtx = Pred->getLocationContext(); 880 ProgramStateRef state = Pred->getState(); 881 SVal loc = state->getSVal(Ex, LCtx); 882 883 // Perform a load. 884 ExplodedNodeSet Tmp; 885 evalLoad(Tmp, U, Ex, Pred, state, loc); 886 887 ExplodedNodeSet Dst2; 888 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx); 889 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 890 891 state = (*I)->getState(); 892 assert(LCtx == (*I)->getLocationContext()); 893 SVal V2_untested = state->getSVal(Ex, LCtx); 894 895 // Propagate unknown and undefined values. 896 if (V2_untested.isUnknownOrUndef()) { 897 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 898 continue; 899 } 900 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>(); 901 902 // Handle all other values. 903 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 904 905 // If the UnaryOperator has non-location type, use its type to create the 906 // constant value. If the UnaryOperator has location type, create the 907 // constant with int type and pointer width. 908 SVal RHS; 909 910 if (U->getType()->isAnyPointerType()) 911 RHS = svalBuilder.makeArrayIndex(1); 912 else if (U->getType()->isIntegralOrEnumerationType()) 913 RHS = svalBuilder.makeIntVal(1, U->getType()); 914 else 915 RHS = UnknownVal(); 916 917 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 918 919 // Conjure a new symbol if necessary to recover precision. 920 if (Result.isUnknown()){ 921 DefinedOrUnknownSVal SymVal = 922 svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 923 Result = SymVal; 924 925 // If the value is a location, ++/-- should always preserve 926 // non-nullness. Check if the original value was non-null, and if so 927 // propagate that constraint. 928 if (Loc::isLocType(U->getType())) { 929 DefinedOrUnknownSVal Constraint = 930 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 931 932 if (!state->assume(Constraint, true)) { 933 // It isn't feasible for the original value to be null. 934 // Propagate this constraint. 935 Constraint = svalBuilder.evalEQ(state, SymVal, 936 svalBuilder.makeZeroVal(U->getType())); 937 938 939 state = state->assume(Constraint, false); 940 assert(state); 941 } 942 } 943 } 944 945 // Since the lvalue-to-rvalue conversion is explicit in the AST, 946 // we bind an l-value if the operator is prefix and an lvalue (in C++). 947 if (U->isGLValue()) 948 state = state->BindExpr(U, LCtx, loc); 949 else 950 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 951 952 // Perform the store. 953 Bldr.takeNodes(*I); 954 ExplodedNodeSet Dst3; 955 evalStore(Dst3, U, U, *I, state, loc, Result); 956 Bldr.addNodes(Dst3); 957 } 958 Dst.insert(Dst2); 959} 960