ExprEngineC.cpp revision 651f13cea278ec967336033dd032faef0e9fc2ec
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_AddressSpaceConversion: 290 case CK_IntegralCast: 291 case CK_NullToPointer: 292 case CK_IntegralToPointer: 293 case CK_PointerToIntegral: 294 case CK_PointerToBoolean: 295 case CK_IntegralToBoolean: 296 case CK_IntegralToFloating: 297 case CK_FloatingToIntegral: 298 case CK_FloatingToBoolean: 299 case CK_FloatingCast: 300 case CK_FloatingRealToComplex: 301 case CK_FloatingComplexToReal: 302 case CK_FloatingComplexToBoolean: 303 case CK_FloatingComplexCast: 304 case CK_FloatingComplexToIntegralComplex: 305 case CK_IntegralRealToComplex: 306 case CK_IntegralComplexToReal: 307 case CK_IntegralComplexToBoolean: 308 case CK_IntegralComplexCast: 309 case CK_IntegralComplexToFloatingComplex: 310 case CK_CPointerToObjCPointerCast: 311 case CK_BlockPointerToObjCPointerCast: 312 case CK_AnyPointerToBlockPointerCast: 313 case CK_ObjCObjectLValueCast: 314 case CK_ZeroToOCLEvent: 315 case CK_LValueBitCast: { 316 // Delegate to SValBuilder to process. 317 SVal V = state->getSVal(Ex, LCtx); 318 V = svalBuilder.evalCast(V, T, ExTy); 319 state = state->BindExpr(CastE, LCtx, V); 320 Bldr.generateNode(CastE, Pred, state); 321 continue; 322 } 323 case CK_DerivedToBase: 324 case CK_UncheckedDerivedToBase: { 325 // For DerivedToBase cast, delegate to the store manager. 326 SVal val = state->getSVal(Ex, LCtx); 327 val = getStoreManager().evalDerivedToBase(val, CastE); 328 state = state->BindExpr(CastE, LCtx, val); 329 Bldr.generateNode(CastE, Pred, state); 330 continue; 331 } 332 // Handle C++ dyn_cast. 333 case CK_Dynamic: { 334 SVal val = state->getSVal(Ex, LCtx); 335 336 // Compute the type of the result. 337 QualType resultType = CastE->getType(); 338 if (CastE->isGLValue()) 339 resultType = getContext().getPointerType(resultType); 340 341 bool Failed = false; 342 343 // Check if the value being cast evaluates to 0. 344 if (val.isZeroConstant()) 345 Failed = true; 346 // Else, evaluate the cast. 347 else 348 val = getStoreManager().evalDynamicCast(val, T, Failed); 349 350 if (Failed) { 351 if (T->isReferenceType()) { 352 // A bad_cast exception is thrown if input value is a reference. 353 // Currently, we model this, by generating a sink. 354 Bldr.generateSink(CastE, Pred, state); 355 continue; 356 } else { 357 // If the cast fails on a pointer, bind to 0. 358 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 359 } 360 } else { 361 // If we don't know if the cast succeeded, conjure a new symbol. 362 if (val.isUnknown()) { 363 DefinedOrUnknownSVal NewSym = 364 svalBuilder.conjureSymbolVal(0, CastE, LCtx, resultType, 365 currBldrCtx->blockCount()); 366 state = state->BindExpr(CastE, LCtx, NewSym); 367 } else 368 // Else, bind to the derived region value. 369 state = state->BindExpr(CastE, LCtx, val); 370 } 371 Bldr.generateNode(CastE, Pred, state); 372 continue; 373 } 374 case CK_NullToMemberPointer: { 375 // FIXME: For now, member pointers are represented by void *. 376 SVal V = svalBuilder.makeNull(); 377 state = state->BindExpr(CastE, LCtx, V); 378 Bldr.generateNode(CastE, Pred, state); 379 continue; 380 } 381 // Various C++ casts that are not handled yet. 382 case CK_ToUnion: 383 case CK_BaseToDerived: 384 case CK_BaseToDerivedMemberPointer: 385 case CK_DerivedToBaseMemberPointer: 386 case CK_ReinterpretMemberPointer: 387 case CK_VectorSplat: { 388 // Recover some path-sensitivty by conjuring a new value. 389 QualType resultType = CastE->getType(); 390 if (CastE->isGLValue()) 391 resultType = getContext().getPointerType(resultType); 392 SVal result = svalBuilder.conjureSymbolVal(0, CastE, LCtx, 393 resultType, 394 currBldrCtx->blockCount()); 395 state = state->BindExpr(CastE, LCtx, result); 396 Bldr.generateNode(CastE, Pred, state); 397 continue; 398 } 399 } 400 } 401} 402 403void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 404 ExplodedNode *Pred, 405 ExplodedNodeSet &Dst) { 406 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 407 408 ProgramStateRef State = Pred->getState(); 409 const LocationContext *LCtx = Pred->getLocationContext(); 410 411 const Expr *Init = CL->getInitializer(); 412 SVal V = State->getSVal(CL->getInitializer(), LCtx); 413 414 if (isa<CXXConstructExpr>(Init)) { 415 // No work needed. Just pass the value up to this expression. 416 } else { 417 assert(isa<InitListExpr>(Init)); 418 Loc CLLoc = State->getLValue(CL, LCtx); 419 State = State->bindLoc(CLLoc, V); 420 421 // Compound literal expressions are a GNU extension in C++. 422 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, 423 // and like temporary objects created by the functional notation T() 424 // CLs are destroyed at the end of the containing full-expression. 425 // HOWEVER, an rvalue of array type is not something the analyzer can 426 // reason about, since we expect all regions to be wrapped in Locs. 427 // So we treat array CLs as lvalues as well, knowing that they will decay 428 // to pointers as soon as they are used. 429 if (CL->isGLValue() || CL->getType()->isArrayType()) 430 V = CLLoc; 431 } 432 433 B.generateNode(CL, Pred, State->BindExpr(CL, LCtx, V)); 434} 435 436void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 437 ExplodedNodeSet &Dst) { 438 // Assumption: The CFG has one DeclStmt per Decl. 439 const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin()); 440 441 if (!VD) { 442 //TODO:AZ: remove explicit insertion after refactoring is done. 443 Dst.insert(Pred); 444 return; 445 } 446 447 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 448 ExplodedNodeSet dstPreVisit; 449 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 450 451 ExplodedNodeSet dstEvaluated; 452 StmtNodeBuilder B(dstPreVisit, dstEvaluated, *currBldrCtx); 453 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 454 I!=E; ++I) { 455 ExplodedNode *N = *I; 456 ProgramStateRef state = N->getState(); 457 const LocationContext *LC = N->getLocationContext(); 458 459 // Decls without InitExpr are not initialized explicitly. 460 if (const Expr *InitEx = VD->getInit()) { 461 462 // Note in the state that the initialization has occurred. 463 ExplodedNode *UpdatedN = N; 464 SVal InitVal = state->getSVal(InitEx, LC); 465 466 if (isa<CXXConstructExpr>(InitEx->IgnoreImplicit())) { 467 // We constructed the object directly in the variable. 468 // No need to bind anything. 469 B.generateNode(DS, UpdatedN, state); 470 } else { 471 // We bound the temp obj region to the CXXConstructExpr. Now recover 472 // the lazy compound value when the variable is not a reference. 473 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 474 !VD->getType()->isReferenceType()) { 475 if (Optional<loc::MemRegionVal> M = 476 InitVal.getAs<loc::MemRegionVal>()) { 477 InitVal = state->getSVal(M->getRegion()); 478 assert(InitVal.getAs<nonloc::LazyCompoundVal>()); 479 } 480 } 481 482 // Recover some path-sensitivity if a scalar value evaluated to 483 // UnknownVal. 484 if (InitVal.isUnknown()) { 485 QualType Ty = InitEx->getType(); 486 if (InitEx->isGLValue()) { 487 Ty = getContext().getPointerType(Ty); 488 } 489 490 InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, 491 currBldrCtx->blockCount()); 492 } 493 494 495 B.takeNodes(UpdatedN); 496 ExplodedNodeSet Dst2; 497 evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true); 498 B.addNodes(Dst2); 499 } 500 } 501 else { 502 B.generateNode(DS, N, state); 503 } 504 } 505 506 getCheckerManager().runCheckersForPostStmt(Dst, B.getResults(), DS, *this); 507} 508 509void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 510 ExplodedNodeSet &Dst) { 511 assert(B->getOpcode() == BO_LAnd || 512 B->getOpcode() == BO_LOr); 513 514 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 515 ProgramStateRef state = Pred->getState(); 516 517 ExplodedNode *N = Pred; 518 while (!N->getLocation().getAs<BlockEntrance>()) { 519 ProgramPoint P = N->getLocation(); 520 assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>()); 521 (void) P; 522 assert(N->pred_size() == 1); 523 N = *N->pred_begin(); 524 } 525 assert(N->pred_size() == 1); 526 N = *N->pred_begin(); 527 BlockEdge BE = N->getLocation().castAs<BlockEdge>(); 528 SVal X; 529 530 // Determine the value of the expression by introspecting how we 531 // got this location in the CFG. This requires looking at the previous 532 // block we were in and what kind of control-flow transfer was involved. 533 const CFGBlock *SrcBlock = BE.getSrc(); 534 // The only terminator (if there is one) that makes sense is a logical op. 535 CFGTerminator T = SrcBlock->getTerminator(); 536 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { 537 (void) Term; 538 assert(Term->isLogicalOp()); 539 assert(SrcBlock->succ_size() == 2); 540 // Did we take the true or false branch? 541 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; 542 X = svalBuilder.makeIntVal(constant, B->getType()); 543 } 544 else { 545 // If there is no terminator, by construction the last statement 546 // in SrcBlock is the value of the enclosing expression. 547 // However, we still need to constrain that value to be 0 or 1. 548 assert(!SrcBlock->empty()); 549 CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>(); 550 const Expr *RHS = cast<Expr>(Elem.getStmt()); 551 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); 552 553 if (RHSVal.isUndef()) { 554 X = RHSVal; 555 } else { 556 DefinedOrUnknownSVal DefinedRHS = RHSVal.castAs<DefinedOrUnknownSVal>(); 557 ProgramStateRef StTrue, StFalse; 558 std::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); 559 if (StTrue) { 560 if (StFalse) { 561 // We can't constrain the value to 0 or 1. 562 // The best we can do is a cast. 563 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); 564 } else { 565 // The value is known to be true. 566 X = getSValBuilder().makeIntVal(1, B->getType()); 567 } 568 } else { 569 // The value is known to be false. 570 assert(StFalse && "Infeasible path!"); 571 X = getSValBuilder().makeIntVal(0, B->getType()); 572 } 573 } 574 } 575 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); 576} 577 578void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 579 ExplodedNode *Pred, 580 ExplodedNodeSet &Dst) { 581 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 582 583 ProgramStateRef state = Pred->getState(); 584 const LocationContext *LCtx = Pred->getLocationContext(); 585 QualType T = getContext().getCanonicalType(IE->getType()); 586 unsigned NumInitElements = IE->getNumInits(); 587 588 if (!IE->isGLValue() && 589 (T->isArrayType() || T->isRecordType() || T->isVectorType() || 590 T->isAnyComplexType())) { 591 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 592 593 // Handle base case where the initializer has no elements. 594 // e.g: static int* myArray[] = {}; 595 if (NumInitElements == 0) { 596 SVal V = svalBuilder.makeCompoundVal(T, vals); 597 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 598 return; 599 } 600 601 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 602 ei = IE->rend(); it != ei; ++it) { 603 SVal V = state->getSVal(cast<Expr>(*it), LCtx); 604 vals = getBasicVals().consVals(V, vals); 605 } 606 607 B.generateNode(IE, Pred, 608 state->BindExpr(IE, LCtx, 609 svalBuilder.makeCompoundVal(T, vals))); 610 return; 611 } 612 613 // Handle scalars: int{5} and int{} and GLvalues. 614 // Note, if the InitListExpr is a GLvalue, it means that there is an address 615 // representing it, so it must have a single init element. 616 assert(NumInitElements <= 1); 617 618 SVal V; 619 if (NumInitElements == 0) 620 V = getSValBuilder().makeZeroVal(T); 621 else 622 V = state->getSVal(IE->getInit(0), LCtx); 623 624 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 625} 626 627void ExprEngine::VisitGuardedExpr(const Expr *Ex, 628 const Expr *L, 629 const Expr *R, 630 ExplodedNode *Pred, 631 ExplodedNodeSet &Dst) { 632 assert(L && R); 633 634 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 635 ProgramStateRef state = Pred->getState(); 636 const LocationContext *LCtx = Pred->getLocationContext(); 637 const CFGBlock *SrcBlock = 0; 638 639 // Find the predecessor block. 640 ProgramStateRef SrcState = state; 641 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { 642 ProgramPoint PP = N->getLocation(); 643 if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) { 644 assert(N->pred_size() == 1); 645 continue; 646 } 647 SrcBlock = PP.castAs<BlockEdge>().getSrc(); 648 SrcState = N->getState(); 649 break; 650 } 651 652 assert(SrcBlock && "missing function entry"); 653 654 // Find the last expression in the predecessor block. That is the 655 // expression that is used for the value of the ternary expression. 656 bool hasValue = false; 657 SVal V; 658 659 for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), 660 E = SrcBlock->rend(); I != E; ++I) { 661 CFGElement CE = *I; 662 if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) { 663 const Expr *ValEx = cast<Expr>(CS->getStmt()); 664 ValEx = ValEx->IgnoreParens(); 665 666 // For GNU extension '?:' operator, the left hand side will be an 667 // OpaqueValueExpr, so get the underlying expression. 668 if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L)) 669 L = OpaqueEx->getSourceExpr(); 670 671 // If the last expression in the predecessor block matches true or false 672 // subexpression, get its the value. 673 if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) { 674 hasValue = true; 675 V = SrcState->getSVal(ValEx, LCtx); 676 } 677 break; 678 } 679 } 680 681 if (!hasValue) 682 V = svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 683 684 // Generate a new node with the binding from the appropriate path. 685 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); 686} 687 688void ExprEngine:: 689VisitOffsetOfExpr(const OffsetOfExpr *OOE, 690 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 691 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 692 APSInt IV; 693 if (OOE->EvaluateAsInt(IV, getContext())) { 694 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 695 assert(OOE->getType()->isBuiltinType()); 696 assert(OOE->getType()->getAs<BuiltinType>()->isInteger()); 697 assert(IV.isSigned() == OOE->getType()->isSignedIntegerType()); 698 SVal X = svalBuilder.makeIntVal(IV); 699 B.generateNode(OOE, Pred, 700 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 701 X)); 702 } 703 // FIXME: Handle the case where __builtin_offsetof is not a constant. 704} 705 706 707void ExprEngine:: 708VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 709 ExplodedNode *Pred, 710 ExplodedNodeSet &Dst) { 711 // FIXME: Prechecks eventually go in ::Visit(). 712 ExplodedNodeSet CheckedSet; 713 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, Ex, *this); 714 715 ExplodedNodeSet EvalSet; 716 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx); 717 718 QualType T = Ex->getTypeOfArgument(); 719 720 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end(); 721 I != E; ++I) { 722 if (Ex->getKind() == UETT_SizeOf) { 723 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 724 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 725 726 // FIXME: Add support for VLA type arguments and VLA expressions. 727 // When that happens, we should probably refactor VLASizeChecker's code. 728 continue; 729 } else if (T->getAs<ObjCObjectType>()) { 730 // Some code tries to take the sizeof an ObjCObjectType, relying that 731 // the compiler has laid out its representation. Just report Unknown 732 // for these. 733 continue; 734 } 735 } 736 737 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 738 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 739 740 ProgramStateRef state = (*I)->getState(); 741 state = state->BindExpr(Ex, (*I)->getLocationContext(), 742 svalBuilder.makeIntVal(amt.getQuantity(), 743 Ex->getType())); 744 Bldr.generateNode(Ex, *I, state); 745 } 746 747 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, Ex, *this); 748} 749 750void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 751 ExplodedNode *Pred, 752 ExplodedNodeSet &Dst) { 753 // FIXME: Prechecks eventually go in ::Visit(). 754 ExplodedNodeSet CheckedSet; 755 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, U, *this); 756 757 ExplodedNodeSet EvalSet; 758 StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx); 759 760 for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end(); 761 I != E; ++I) { 762 switch (U->getOpcode()) { 763 default: { 764 Bldr.takeNodes(*I); 765 ExplodedNodeSet Tmp; 766 VisitIncrementDecrementOperator(U, *I, Tmp); 767 Bldr.addNodes(Tmp); 768 break; 769 } 770 case UO_Real: { 771 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 772 773 // FIXME: We don't have complex SValues yet. 774 if (Ex->getType()->isAnyComplexType()) { 775 // Just report "Unknown." 776 break; 777 } 778 779 // For all other types, UO_Real is an identity operation. 780 assert (U->getType() == Ex->getType()); 781 ProgramStateRef state = (*I)->getState(); 782 const LocationContext *LCtx = (*I)->getLocationContext(); 783 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, 784 state->getSVal(Ex, LCtx))); 785 break; 786 } 787 788 case UO_Imag: { 789 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 790 // FIXME: We don't have complex SValues yet. 791 if (Ex->getType()->isAnyComplexType()) { 792 // Just report "Unknown." 793 break; 794 } 795 // For all other types, UO_Imag returns 0. 796 ProgramStateRef state = (*I)->getState(); 797 const LocationContext *LCtx = (*I)->getLocationContext(); 798 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 799 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, X)); 800 break; 801 } 802 803 case UO_Plus: 804 assert(!U->isGLValue()); 805 // FALL-THROUGH. 806 case UO_Deref: 807 case UO_AddrOf: 808 case UO_Extension: { 809 // FIXME: We can probably just have some magic in Environment::getSVal() 810 // that propagates values, instead of creating a new node here. 811 // 812 // Unary "+" is a no-op, similar to a parentheses. We still have places 813 // where it may be a block-level expression, so we need to 814 // generate an extra node that just propagates the value of the 815 // subexpression. 816 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 817 ProgramStateRef state = (*I)->getState(); 818 const LocationContext *LCtx = (*I)->getLocationContext(); 819 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, 820 state->getSVal(Ex, LCtx))); 821 break; 822 } 823 824 case UO_LNot: 825 case UO_Minus: 826 case UO_Not: { 827 assert (!U->isGLValue()); 828 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 829 ProgramStateRef state = (*I)->getState(); 830 const LocationContext *LCtx = (*I)->getLocationContext(); 831 832 // Get the value of the subexpression. 833 SVal V = state->getSVal(Ex, LCtx); 834 835 if (V.isUnknownOrUndef()) { 836 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V)); 837 break; 838 } 839 840 switch (U->getOpcode()) { 841 default: 842 llvm_unreachable("Invalid Opcode."); 843 case UO_Not: 844 // FIXME: Do we need to handle promotions? 845 state = state->BindExpr(U, LCtx, evalComplement(V.castAs<NonLoc>())); 846 break; 847 case UO_Minus: 848 // FIXME: Do we need to handle promotions? 849 state = state->BindExpr(U, LCtx, evalMinus(V.castAs<NonLoc>())); 850 break; 851 case UO_LNot: 852 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 853 // 854 // Note: technically we do "E == 0", but this is the same in the 855 // transfer functions as "0 == E". 856 SVal Result; 857 if (Optional<Loc> LV = V.getAs<Loc>()) { 858 Loc X = svalBuilder.makeNull(); 859 Result = evalBinOp(state, BO_EQ, *LV, X, U->getType()); 860 } 861 else if (Ex->getType()->isFloatingType()) { 862 // FIXME: handle floating point types. 863 Result = UnknownVal(); 864 } else { 865 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 866 Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X, 867 U->getType()); 868 } 869 870 state = state->BindExpr(U, LCtx, Result); 871 break; 872 } 873 Bldr.generateNode(U, *I, state); 874 break; 875 } 876 } 877 } 878 879 getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, U, *this); 880} 881 882void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 883 ExplodedNode *Pred, 884 ExplodedNodeSet &Dst) { 885 // Handle ++ and -- (both pre- and post-increment). 886 assert (U->isIncrementDecrementOp()); 887 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 888 889 const LocationContext *LCtx = Pred->getLocationContext(); 890 ProgramStateRef state = Pred->getState(); 891 SVal loc = state->getSVal(Ex, LCtx); 892 893 // Perform a load. 894 ExplodedNodeSet Tmp; 895 evalLoad(Tmp, U, Ex, Pred, state, loc); 896 897 ExplodedNodeSet Dst2; 898 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx); 899 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 900 901 state = (*I)->getState(); 902 assert(LCtx == (*I)->getLocationContext()); 903 SVal V2_untested = state->getSVal(Ex, LCtx); 904 905 // Propagate unknown and undefined values. 906 if (V2_untested.isUnknownOrUndef()) { 907 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 908 continue; 909 } 910 DefinedSVal V2 = V2_untested.castAs<DefinedSVal>(); 911 912 // Handle all other values. 913 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 914 915 // If the UnaryOperator has non-location type, use its type to create the 916 // constant value. If the UnaryOperator has location type, create the 917 // constant with int type and pointer width. 918 SVal RHS; 919 920 if (U->getType()->isAnyPointerType()) 921 RHS = svalBuilder.makeArrayIndex(1); 922 else if (U->getType()->isIntegralOrEnumerationType()) 923 RHS = svalBuilder.makeIntVal(1, U->getType()); 924 else 925 RHS = UnknownVal(); 926 927 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 928 929 // Conjure a new symbol if necessary to recover precision. 930 if (Result.isUnknown()){ 931 DefinedOrUnknownSVal SymVal = 932 svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 933 Result = SymVal; 934 935 // If the value is a location, ++/-- should always preserve 936 // non-nullness. Check if the original value was non-null, and if so 937 // propagate that constraint. 938 if (Loc::isLocType(U->getType())) { 939 DefinedOrUnknownSVal Constraint = 940 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 941 942 if (!state->assume(Constraint, true)) { 943 // It isn't feasible for the original value to be null. 944 // Propagate this constraint. 945 Constraint = svalBuilder.evalEQ(state, SymVal, 946 svalBuilder.makeZeroVal(U->getType())); 947 948 949 state = state->assume(Constraint, false); 950 assert(state); 951 } 952 } 953 } 954 955 // Since the lvalue-to-rvalue conversion is explicit in the AST, 956 // we bind an l-value if the operator is prefix and an lvalue (in C++). 957 if (U->isGLValue()) 958 state = state->BindExpr(U, LCtx, loc); 959 else 960 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 961 962 // Perform the store. 963 Bldr.takeNodes(*I); 964 ExplodedNodeSet Dst3; 965 evalStore(Dst3, U, U, *I, state, loc, Result); 966 Bldr.addNodes(Dst3); 967 } 968 Dst.insert(Dst2); 969} 970