ExprEngineC.cpp revision 249423
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()->isIntegerType() && RightV.isUnknown()) { 72 RightV = svalBuilder.conjureSymbolVal(RHS, LCtx, RHS->getType(), 73 Count); 74 } 75 if (RightV.getAs<Loc>() && 76 LHS->getType()->isIntegerType() && LeftV.isUnknown()) { 77 LeftV = svalBuilder.conjureSymbolVal(LHS, LCtx, LHS->getType(), 78 Count); 79 } 80 } 81 82 // Process non-assignments except commas or short-circuited 83 // logical expressions (LAnd and LOr). 84 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType()); 85 if (Result.isUnknown()) { 86 Bldr.generateNode(B, *it, state); 87 continue; 88 } 89 90 state = state->BindExpr(B, LCtx, Result); 91 Bldr.generateNode(B, *it, state); 92 continue; 93 } 94 95 assert (B->isCompoundAssignmentOp()); 96 97 switch (Op) { 98 default: 99 llvm_unreachable("Invalid opcode for compound assignment."); 100 case BO_MulAssign: Op = BO_Mul; break; 101 case BO_DivAssign: Op = BO_Div; break; 102 case BO_RemAssign: Op = BO_Rem; break; 103 case BO_AddAssign: Op = BO_Add; break; 104 case BO_SubAssign: Op = BO_Sub; break; 105 case BO_ShlAssign: Op = BO_Shl; break; 106 case BO_ShrAssign: Op = BO_Shr; break; 107 case BO_AndAssign: Op = BO_And; break; 108 case BO_XorAssign: Op = BO_Xor; break; 109 case BO_OrAssign: Op = BO_Or; break; 110 } 111 112 // Perform a load (the LHS). This performs the checks for 113 // null dereferences, and so on. 114 ExplodedNodeSet Tmp; 115 SVal location = LeftV; 116 evalLoad(Tmp, B, LHS, *it, state, location); 117 118 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; 119 ++I) { 120 121 state = (*I)->getState(); 122 const LocationContext *LCtx = (*I)->getLocationContext(); 123 SVal V = state->getSVal(LHS, LCtx); 124 125 // Get the computation type. 126 QualType CTy = 127 cast<CompoundAssignOperator>(B)->getComputationResultType(); 128 CTy = getContext().getCanonicalType(CTy); 129 130 QualType CLHSTy = 131 cast<CompoundAssignOperator>(B)->getComputationLHSType(); 132 CLHSTy = getContext().getCanonicalType(CLHSTy); 133 134 QualType LTy = getContext().getCanonicalType(LHS->getType()); 135 136 // Promote LHS. 137 V = svalBuilder.evalCast(V, CLHSTy, LTy); 138 139 // Compute the result of the operation. 140 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy), 141 B->getType(), CTy); 142 143 // EXPERIMENTAL: "Conjured" symbols. 144 // FIXME: Handle structs. 145 146 SVal LHSVal; 147 148 if (Result.isUnknown()) { 149 // The symbolic value is actually for the type of the left-hand side 150 // expression, not the computation type, as this is the value the 151 // LValue on the LHS will bind to. 152 LHSVal = svalBuilder.conjureSymbolVal(0, B->getRHS(), LCtx, LTy, 153 currBldrCtx->blockCount()); 154 // However, we need to convert the symbol to the computation type. 155 Result = svalBuilder.evalCast(LHSVal, CTy, LTy); 156 } 157 else { 158 // The left-hand side may bind to a different value then the 159 // computation type. 160 LHSVal = svalBuilder.evalCast(Result, LTy, CTy); 161 } 162 163 // In C++, assignment and compound assignment operators return an 164 // lvalue. 165 if (B->isGLValue()) 166 state = state->BindExpr(B, LCtx, location); 167 else 168 state = state->BindExpr(B, LCtx, Result); 169 170 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal); 171 } 172 } 173 174 // FIXME: postvisits eventually go in ::Visit() 175 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this); 176} 177 178void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred, 179 ExplodedNodeSet &Dst) { 180 181 CanQualType T = getContext().getCanonicalType(BE->getType()); 182 183 // Get the value of the block itself. 184 SVal V = svalBuilder.getBlockPointer(BE->getBlockDecl(), T, 185 Pred->getLocationContext()); 186 187 ProgramStateRef State = Pred->getState(); 188 189 // If we created a new MemRegion for the block, we should explicitly bind 190 // the captured variables. 191 if (const BlockDataRegion *BDR = 192 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) { 193 194 BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(), 195 E = BDR->referenced_vars_end(); 196 197 for (; I != E; ++I) { 198 const MemRegion *capturedR = I.getCapturedRegion(); 199 const MemRegion *originalR = I.getOriginalRegion(); 200 if (capturedR != originalR) { 201 SVal originalV = State->getSVal(loc::MemRegionVal(originalR)); 202 State = State->bindLoc(loc::MemRegionVal(capturedR), originalV); 203 } 204 } 205 } 206 207 ExplodedNodeSet Tmp; 208 StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx); 209 Bldr.generateNode(BE, Pred, 210 State->BindExpr(BE, Pred->getLocationContext(), V), 211 0, ProgramPoint::PostLValueKind); 212 213 // FIXME: Move all post/pre visits to ::Visit(). 214 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this); 215} 216 217void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, 218 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 219 220 ExplodedNodeSet dstPreStmt; 221 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this); 222 223 if (CastE->getCastKind() == CK_LValueToRValue) { 224 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 225 I!=E; ++I) { 226 ExplodedNode *subExprNode = *I; 227 ProgramStateRef state = subExprNode->getState(); 228 const LocationContext *LCtx = subExprNode->getLocationContext(); 229 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx)); 230 } 231 return; 232 } 233 234 // All other casts. 235 QualType T = CastE->getType(); 236 QualType ExTy = Ex->getType(); 237 238 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE)) 239 T = ExCast->getTypeAsWritten(); 240 241 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx); 242 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 243 I != E; ++I) { 244 245 Pred = *I; 246 ProgramStateRef state = Pred->getState(); 247 const LocationContext *LCtx = Pred->getLocationContext(); 248 249 switch (CastE->getCastKind()) { 250 case CK_LValueToRValue: 251 llvm_unreachable("LValueToRValue casts handled earlier."); 252 case CK_ToVoid: 253 continue; 254 // The analyzer doesn't do anything special with these casts, 255 // since it understands retain/release semantics already. 256 case CK_ARCProduceObject: 257 case CK_ARCConsumeObject: 258 case CK_ARCReclaimReturnedObject: 259 case CK_ARCExtendBlockObject: // Fall-through. 260 case CK_CopyAndAutoreleaseBlockObject: 261 // The analyser can ignore atomic casts for now, although some future 262 // checkers may want to make certain that you're not modifying the same 263 // value through atomic and nonatomic pointers. 264 case CK_AtomicToNonAtomic: 265 case CK_NonAtomicToAtomic: 266 // True no-ops. 267 case CK_NoOp: 268 case CK_ConstructorConversion: 269 case CK_UserDefinedConversion: 270 case CK_FunctionToPointerDecay: 271 case CK_BuiltinFnToFnPtr: { 272 // Copy the SVal of Ex to CastE. 273 ProgramStateRef state = Pred->getState(); 274 const LocationContext *LCtx = Pred->getLocationContext(); 275 SVal V = state->getSVal(Ex, LCtx); 276 state = state->BindExpr(CastE, LCtx, V); 277 Bldr.generateNode(CastE, Pred, state); 278 continue; 279 } 280 case CK_MemberPointerToBoolean: 281 // FIXME: For now, member pointers are represented by void *. 282 // FALLTHROUGH 283 case CK_Dependent: 284 case CK_ArrayToPointerDecay: 285 case CK_BitCast: 286 case CK_IntegralCast: 287 case CK_NullToPointer: 288 case CK_IntegralToPointer: 289 case CK_PointerToIntegral: 290 case CK_PointerToBoolean: 291 case CK_IntegralToBoolean: 292 case CK_IntegralToFloating: 293 case CK_FloatingToIntegral: 294 case CK_FloatingToBoolean: 295 case CK_FloatingCast: 296 case CK_FloatingRealToComplex: 297 case CK_FloatingComplexToReal: 298 case CK_FloatingComplexToBoolean: 299 case CK_FloatingComplexCast: 300 case CK_FloatingComplexToIntegralComplex: 301 case CK_IntegralRealToComplex: 302 case CK_IntegralComplexToReal: 303 case CK_IntegralComplexToBoolean: 304 case CK_IntegralComplexCast: 305 case CK_IntegralComplexToFloatingComplex: 306 case CK_CPointerToObjCPointerCast: 307 case CK_BlockPointerToObjCPointerCast: 308 case CK_AnyPointerToBlockPointerCast: 309 case CK_ObjCObjectLValueCast: 310 case CK_ZeroToOCLEvent: { 311 // Delegate to SValBuilder to process. 312 SVal V = state->getSVal(Ex, LCtx); 313 V = svalBuilder.evalCast(V, T, ExTy); 314 state = state->BindExpr(CastE, LCtx, V); 315 Bldr.generateNode(CastE, Pred, state); 316 continue; 317 } 318 case CK_DerivedToBase: 319 case CK_UncheckedDerivedToBase: { 320 // For DerivedToBase cast, delegate to the store manager. 321 SVal val = state->getSVal(Ex, LCtx); 322 val = getStoreManager().evalDerivedToBase(val, CastE); 323 state = state->BindExpr(CastE, LCtx, val); 324 Bldr.generateNode(CastE, Pred, state); 325 continue; 326 } 327 // Handle C++ dyn_cast. 328 case CK_Dynamic: { 329 SVal val = state->getSVal(Ex, LCtx); 330 331 // Compute the type of the result. 332 QualType resultType = CastE->getType(); 333 if (CastE->isGLValue()) 334 resultType = getContext().getPointerType(resultType); 335 336 bool Failed = false; 337 338 // Check if the value being cast evaluates to 0. 339 if (val.isZeroConstant()) 340 Failed = true; 341 // Else, evaluate the cast. 342 else 343 val = getStoreManager().evalDynamicCast(val, T, Failed); 344 345 if (Failed) { 346 if (T->isReferenceType()) { 347 // A bad_cast exception is thrown if input value is a reference. 348 // Currently, we model this, by generating a sink. 349 Bldr.generateSink(CastE, Pred, state); 350 continue; 351 } else { 352 // If the cast fails on a pointer, bind to 0. 353 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 354 } 355 } else { 356 // If we don't know if the cast succeeded, conjure a new symbol. 357 if (val.isUnknown()) { 358 DefinedOrUnknownSVal NewSym = 359 svalBuilder.conjureSymbolVal(0, CastE, LCtx, resultType, 360 currBldrCtx->blockCount()); 361 state = state->BindExpr(CastE, LCtx, NewSym); 362 } else 363 // Else, bind to the derived region value. 364 state = state->BindExpr(CastE, LCtx, val); 365 } 366 Bldr.generateNode(CastE, Pred, state); 367 continue; 368 } 369 case CK_NullToMemberPointer: { 370 // FIXME: For now, member pointers are represented by void *. 371 SVal V = svalBuilder.makeIntValWithPtrWidth(0, true); 372 state = state->BindExpr(CastE, LCtx, V); 373 Bldr.generateNode(CastE, Pred, state); 374 continue; 375 } 376 // Various C++ casts that are not handled yet. 377 case CK_ToUnion: 378 case CK_BaseToDerived: 379 case CK_BaseToDerivedMemberPointer: 380 case CK_DerivedToBaseMemberPointer: 381 case CK_ReinterpretMemberPointer: 382 case CK_VectorSplat: 383 case CK_LValueBitCast: { 384 // Recover some path-sensitivty by conjuring a new value. 385 QualType resultType = CastE->getType(); 386 if (CastE->isGLValue()) 387 resultType = getContext().getPointerType(resultType); 388 SVal result = svalBuilder.conjureSymbolVal(0, CastE, LCtx, 389 resultType, 390 currBldrCtx->blockCount()); 391 state = state->BindExpr(CastE, LCtx, result); 392 Bldr.generateNode(CastE, Pred, state); 393 continue; 394 } 395 } 396 } 397} 398 399void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 400 ExplodedNode *Pred, 401 ExplodedNodeSet &Dst) { 402 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 403 404 const InitListExpr *ILE 405 = cast<InitListExpr>(CL->getInitializer()->IgnoreParens()); 406 407 ProgramStateRef state = Pred->getState(); 408 SVal ILV = state->getSVal(ILE, Pred->getLocationContext()); 409 const LocationContext *LC = Pred->getLocationContext(); 410 state = state->bindCompoundLiteral(CL, LC, ILV); 411 412 // Compound literal expressions are a GNU extension in C++. 413 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, 414 // and like temporary objects created by the functional notation T() 415 // CLs are destroyed at the end of the containing full-expression. 416 // HOWEVER, an rvalue of array type is not something the analyzer can 417 // reason about, since we expect all regions to be wrapped in Locs. 418 // So we treat array CLs as lvalues as well, knowing that they will decay 419 // to pointers as soon as they are used. 420 if (CL->isGLValue() || CL->getType()->isArrayType()) 421 B.generateNode(CL, Pred, state->BindExpr(CL, LC, state->getLValue(CL, LC))); 422 else 423 B.generateNode(CL, Pred, state->BindExpr(CL, LC, ILV)); 424} 425 426void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 427 ExplodedNodeSet &Dst) { 428 // Assumption: The CFG has one DeclStmt per Decl. 429 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin()); 430 431 if (!VD) { 432 //TODO:AZ: remove explicit insertion after refactoring is done. 433 Dst.insert(Pred); 434 return; 435 } 436 437 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 438 ExplodedNodeSet dstPreVisit; 439 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 440 441 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 442 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 443 I!=E; ++I) { 444 ExplodedNode *N = *I; 445 ProgramStateRef state = N->getState(); 446 const LocationContext *LC = N->getLocationContext(); 447 448 // Decls without InitExpr are not initialized explicitly. 449 if (const Expr *InitEx = VD->getInit()) { 450 451 // Note in the state that the initialization has occurred. 452 ExplodedNode *UpdatedN = N; 453 SVal InitVal = state->getSVal(InitEx, LC); 454 455 if (isa<CXXConstructExpr>(InitEx->IgnoreImplicit())) { 456 // We constructed the object directly in the variable. 457 // No need to bind anything. 458 B.generateNode(DS, UpdatedN, state); 459 } else { 460 // We bound the temp obj region to the CXXConstructExpr. Now recover 461 // the lazy compound value when the variable is not a reference. 462 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 463 !VD->getType()->isReferenceType()) { 464 if (Optional<loc::MemRegionVal> M = 465 InitVal.getAs<loc::MemRegionVal>()) { 466 InitVal = state->getSVal(M->getRegion()); 467 assert(InitVal.getAs<nonloc::LazyCompoundVal>()); 468 } 469 } 470 471 // Recover some path-sensitivity if a scalar value evaluated to 472 // UnknownVal. 473 if (InitVal.isUnknown()) { 474 QualType Ty = InitEx->getType(); 475 if (InitEx->isGLValue()) { 476 Ty = getContext().getPointerType(Ty); 477 } 478 479 InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, 480 currBldrCtx->blockCount()); 481 } 482 483 484 B.takeNodes(UpdatedN); 485 ExplodedNodeSet Dst2; 486 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true); 487 B.addNodes(Dst2); 488 } 489 } 490 else { 491 B.generateNode(DS, N, state); 492 } 493 } 494} 495 496void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 497 ExplodedNodeSet &Dst) { 498 assert(B->getOpcode() == BO_LAnd || 499 B->getOpcode() == BO_LOr); 500 501 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 502 ProgramStateRef state = Pred->getState(); 503 504 ExplodedNode *N = Pred; 505 while (!N->getLocation().getAs<BlockEntrance>()) { 506 ProgramPoint P = N->getLocation(); 507 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>()); 508 (void) P; 509 assert(N->pred_size() == 1); 510 N = *N->pred_begin(); 511 } 512 assert(N->pred_size() == 1); 513 N = *N->pred_begin(); 514 BlockEdge BE = N->getLocation().castAs<BlockEdge>(); 515 SVal X; 516 517 // Determine the value of the expression by introspecting how we 518 // got this location in the CFG. This requires looking at the previous 519 // block we were in and what kind of control-flow transfer was involved. 520 const CFGBlock *SrcBlock = BE.getSrc(); 521 // The only terminator (if there is one) that makes sense is a logical op. 522 CFGTerminator T = SrcBlock->getTerminator(); 523 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { 524 (void) Term; 525 assert(Term->isLogicalOp()); 526 assert(SrcBlock->succ_size() == 2); 527 // Did we take the true or false branch? 528 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; 529 X = svalBuilder.makeIntVal(constant, B->getType()); 530 } 531 else { 532 // If there is no terminator, by construction the last statement 533 // in SrcBlock is the value of the enclosing expression. 534 // However, we still need to constrain that value to be 0 or 1. 535 assert(!SrcBlock->empty()); 536 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>(); 537 const Expr *RHS = cast<Expr>(Elem.getStmt()); 538 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); 539 540 if (RHSVal.isUndef()) { 541 X = RHSVal; 542 } else { 543 DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>(); 544 ProgramStateRef StTrue, StFalse; 545 llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); 546 if (StTrue) { 547 if (StFalse) { 548 // We can't constrain the value to 0 or 1. 549 // The best we can do is a cast. 550 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); 551 } else { 552 // The value is known to be true. 553 X = getSValBuilder().makeIntVal(1, B->getType()); 554 } 555 } else { 556 // The value is known to be false. 557 assert(StFalse && "Infeasible path!"); 558 X = getSValBuilder().makeIntVal(0, B->getType()); 559 } 560 } 561 } 562 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); 563} 564 565void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 566 ExplodedNode *Pred, 567 ExplodedNodeSet &Dst) { 568 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 569 570 ProgramStateRef state = Pred->getState(); 571 const LocationContext *LCtx = Pred->getLocationContext(); 572 QualType T = getContext().getCanonicalType(IE->getType()); 573 unsigned NumInitElements = IE->getNumInits(); 574 575 if (T->isArrayType() || T->isRecordType() || T->isVectorType() || 576 T->isAnyComplexType()) { 577 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 578 579 // Handle base case where the initializer has no elements. 580 // e.g: static int* myArray[] = {}; 581 if (NumInitElements == 0) { 582 SVal V = svalBuilder.makeCompoundVal(T, vals); 583 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 584 return; 585 } 586 587 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 588 ei = IE->rend(); it != ei; ++it) { 589 SVal V = state->getSVal(cast<Expr>(*it), LCtx); 590 if (dyn_cast_or_null<CXXTempObjectRegion>(V.getAsRegion())) 591 V = UnknownVal(); 592 vals = getBasicVals().consVals(V, vals); 593 } 594 595 B.generateNode(IE, Pred, 596 state->BindExpr(IE, LCtx, 597 svalBuilder.makeCompoundVal(T, vals))); 598 return; 599 } 600 601 // Handle scalars: int{5} and int{}. 602 assert(NumInitElements <= 1); 603 604 SVal V; 605 if (NumInitElements == 0) 606 V = getSValBuilder().makeZeroVal(T); 607 else 608 V = state->getSVal(IE->getInit(0), LCtx); 609 610 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 611} 612 613void ExprEngine::VisitGuardedExpr(const Expr *Ex, 614 const Expr *L, 615 const Expr *R, 616 ExplodedNode *Pred, 617 ExplodedNodeSet &Dst) { 618 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 619 ProgramStateRef state = Pred->getState(); 620 const LocationContext *LCtx = Pred->getLocationContext(); 621 const CFGBlock *SrcBlock = 0; 622 623 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { 624 ProgramPoint PP = N->getLocation(); 625 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) { 626 assert(N->pred_size() == 1); 627 continue; 628 } 629 SrcBlock = PP.castAs<BlockEdge>().getSrc(); 630 break; 631 } 632 633 assert(SrcBlock && "missing function entry"); 634 635 // Find the last expression in the predecessor block. That is the 636 // expression that is used for the value of the ternary expression. 637 bool hasValue = false; 638 SVal V; 639 640 for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), 641 E = SrcBlock->rend(); I != E; ++I) { 642 CFGElement CE = *I; 643 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) { 644 const Expr *ValEx = cast<Expr>(CS->getStmt()); 645 hasValue = true; 646 V = state->getSVal(ValEx, LCtx); 647 break; 648 } 649 } 650 651 assert(hasValue); 652 (void) hasValue; 653 654 // Generate a new node with the binding from the appropriate path. 655 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); 656} 657 658void ExprEngine:: 659VisitOffsetOfExpr(const OffsetOfExpr *OOE, 660 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 661 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 662 APSInt IV; 663 if (OOE->EvaluateAsInt(IV, getContext())) { 664 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 665 assert(OOE->getType()->isIntegerType()); 666 assert(IV.isSigned() == OOE->getType()->isSignedIntegerOrEnumerationType()); 667 SVal X = svalBuilder.makeIntVal(IV); 668 B.generateNode(OOE, Pred, 669 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 670 X)); 671 } 672 // FIXME: Handle the case where __builtin_offsetof is not a constant. 673} 674 675 676void ExprEngine:: 677VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 678 ExplodedNode *Pred, 679 ExplodedNodeSet &Dst) { 680 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 681 682 QualType T = Ex->getTypeOfArgument(); 683 684 if (Ex->getKind() == UETT_SizeOf) { 685 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 686 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 687 688 // FIXME: Add support for VLA type arguments and VLA expressions. 689 // When that happens, we should probably refactor VLASizeChecker's code. 690 return; 691 } 692 else if (T->getAs<ObjCObjectType>()) { 693 // Some code tries to take the sizeof an ObjCObjectType, relying that 694 // the compiler has laid out its representation. Just report Unknown 695 // for these. 696 return; 697 } 698 } 699 700 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 701 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 702 703 ProgramStateRef state = Pred->getState(); 704 state = state->BindExpr(Ex, Pred->getLocationContext(), 705 svalBuilder.makeIntVal(amt.getQuantity(), 706 Ex->getType())); 707 Bldr.generateNode(Ex, Pred, state); 708} 709 710void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 711 ExplodedNode *Pred, 712 ExplodedNodeSet &Dst) { 713 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 714 switch (U->getOpcode()) { 715 default: { 716 Bldr.takeNodes(Pred); 717 ExplodedNodeSet Tmp; 718 VisitIncrementDecrementOperator(U, Pred, Tmp); 719 Bldr.addNodes(Tmp); 720 } 721 break; 722 case UO_Real: { 723 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 724 725 // FIXME: We don't have complex SValues yet. 726 if (Ex->getType()->isAnyComplexType()) { 727 // Just report "Unknown." 728 break; 729 } 730 731 // For all other types, UO_Real is an identity operation. 732 assert (U->getType() == Ex->getType()); 733 ProgramStateRef state = Pred->getState(); 734 const LocationContext *LCtx = Pred->getLocationContext(); 735 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 736 state->getSVal(Ex, LCtx))); 737 break; 738 } 739 740 case UO_Imag: { 741 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 742 // FIXME: We don't have complex SValues yet. 743 if (Ex->getType()->isAnyComplexType()) { 744 // Just report "Unknown." 745 break; 746 } 747 // For all other types, UO_Imag returns 0. 748 ProgramStateRef state = Pred->getState(); 749 const LocationContext *LCtx = Pred->getLocationContext(); 750 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 751 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, X)); 752 break; 753 } 754 755 case UO_Plus: 756 assert(!U->isGLValue()); 757 // FALL-THROUGH. 758 case UO_Deref: 759 case UO_AddrOf: 760 case UO_Extension: { 761 // FIXME: We can probably just have some magic in Environment::getSVal() 762 // that propagates values, instead of creating a new node here. 763 // 764 // Unary "+" is a no-op, similar to a parentheses. We still have places 765 // where it may be a block-level expression, so we need to 766 // generate an extra node that just propagates the value of the 767 // subexpression. 768 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 769 ProgramStateRef state = Pred->getState(); 770 const LocationContext *LCtx = Pred->getLocationContext(); 771 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 772 state->getSVal(Ex, LCtx))); 773 break; 774 } 775 776 case UO_LNot: 777 case UO_Minus: 778 case UO_Not: { 779 assert (!U->isGLValue()); 780 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 781 ProgramStateRef state = Pred->getState(); 782 const LocationContext *LCtx = Pred->getLocationContext(); 783 784 // Get the value of the subexpression. 785 SVal V = state->getSVal(Ex, LCtx); 786 787 if (V.isUnknownOrUndef()) { 788 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, V)); 789 break; 790 } 791 792 switch (U->getOpcode()) { 793 default: 794 llvm_unreachable("Invalid Opcode."); 795 case UO_Not: 796 // FIXME: Do we need to handle promotions? 797 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>())); 798 break; 799 case UO_Minus: 800 // FIXME: Do we need to handle promotions? 801 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>())); 802 break; 803 case UO_LNot: 804 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 805 // 806 // Note: technically we do "E == 0", but this is the same in the 807 // transfer functions as "0 == E". 808 SVal Result; 809 if (Optional<Loc> LV = V.getAs<Loc>()) { 810 Loc X = svalBuilder.makeNull(); 811 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType()); 812 } 813 else if (Ex->getType()->isFloatingType()) { 814 // FIXME: handle floating point types. 815 Result = UnknownVal(); 816 } else { 817 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 818 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X, 819 U->getType()); 820 } 821 822 state = state->BindExpr(U, LCtx, Result); 823 break; 824 } 825 Bldr.generateNode(U, Pred, state); 826 break; 827 } 828 } 829 830} 831 832void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 833 ExplodedNode *Pred, 834 ExplodedNodeSet &Dst) { 835 // Handle ++ and -- (both pre- and post-increment). 836 assert (U->isIncrementDecrementOp()); 837 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 838 839 const LocationContext *LCtx = Pred->getLocationContext(); 840 ProgramStateRef state = Pred->getState(); 841 SVal loc = state->getSVal(Ex, LCtx); 842 843 // Perform a load. 844 ExplodedNodeSet Tmp; 845 evalLoad(Tmp, U, Ex, Pred, state, loc); 846 847 ExplodedNodeSet Dst2; 848 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx); 849 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 850 851 state = (*I)->getState(); 852 assert(LCtx == (*I)->getLocationContext()); 853 SVal V2_untested = state->getSVal(Ex, LCtx); 854 855 // Propagate unknown and undefined values. 856 if (V2_untested.isUnknownOrUndef()) { 857 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 858 continue; 859 } 860 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>(); 861 862 // Handle all other values. 863 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 864 865 // If the UnaryOperator has non-location type, use its type to create the 866 // constant value. If the UnaryOperator has location type, create the 867 // constant with int type and pointer width. 868 SVal RHS; 869 870 if (U->getType()->isAnyPointerType()) 871 RHS = svalBuilder.makeArrayIndex(1); 872 else if (U->getType()->isIntegralOrEnumerationType()) 873 RHS = svalBuilder.makeIntVal(1, U->getType()); 874 else 875 RHS = UnknownVal(); 876 877 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 878 879 // Conjure a new symbol if necessary to recover precision. 880 if (Result.isUnknown()){ 881 DefinedOrUnknownSVal SymVal = 882 svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 883 Result = SymVal; 884 885 // If the value is a location, ++/-- should always preserve 886 // non-nullness. Check if the original value was non-null, and if so 887 // propagate that constraint. 888 if (Loc::isLocType(U->getType())) { 889 DefinedOrUnknownSVal Constraint = 890 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 891 892 if (!state->assume(Constraint, true)) { 893 // It isn't feasible for the original value to be null. 894 // Propagate this constraint. 895 Constraint = svalBuilder.evalEQ(state, SymVal, 896 svalBuilder.makeZeroVal(U->getType())); 897 898 899 state = state->assume(Constraint, false); 900 assert(state); 901 } 902 } 903 } 904 905 // Since the lvalue-to-rvalue conversion is explicit in the AST, 906 // we bind an l-value if the operator is prefix and an lvalue (in C++). 907 if (U->isGLValue()) 908 state = state->BindExpr(U, LCtx, loc); 909 else 910 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 911 912 // Perform the store. 913 Bldr.takeNodes(*I); 914 ExplodedNodeSet Dst3; 915 evalStore(Dst3, U, U, *I, state, loc, Result); 916 Bldr.addNodes(Dst3); 917 } 918 Dst.insert(Dst2); 919} 920