ExprEngineC.cpp revision 66c486f275531df6362b3511fc3af6563561801b
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/StaticAnalyzer/Core/CheckerManager.h" 15#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 16 17using namespace clang; 18using namespace ento; 19using llvm::APSInt; 20 21void ExprEngine::VisitBinaryOperator(const BinaryOperator* B, 22 ExplodedNode *Pred, 23 ExplodedNodeSet &Dst) { 24 25 Expr *LHS = B->getLHS()->IgnoreParens(); 26 Expr *RHS = B->getRHS()->IgnoreParens(); 27 28 // FIXME: Prechecks eventually go in ::Visit(). 29 ExplodedNodeSet CheckedSet; 30 ExplodedNodeSet Tmp2; 31 getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this); 32 33 // With both the LHS and RHS evaluated, process the operation itself. 34 for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end(); 35 it != ei; ++it) { 36 37 ProgramStateRef state = (*it)->getState(); 38 const LocationContext *LCtx = (*it)->getLocationContext(); 39 SVal LeftV = state->getSVal(LHS, LCtx); 40 SVal RightV = state->getSVal(RHS, LCtx); 41 42 BinaryOperator::Opcode Op = B->getOpcode(); 43 44 if (Op == BO_Assign) { 45 // EXPERIMENTAL: "Conjured" symbols. 46 // FIXME: Handle structs. 47 if (RightV.isUnknown()) { 48 unsigned Count = currBldrCtx->blockCount(); 49 RightV = svalBuilder.conjureSymbolVal(0, B->getRHS(), LCtx, Count); 50 } 51 // Simulate the effects of a "store": bind the value of the RHS 52 // to the L-Value represented by the LHS. 53 SVal ExprVal = B->isGLValue() ? LeftV : RightV; 54 evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal), 55 LeftV, RightV); 56 continue; 57 } 58 59 if (!B->isAssignmentOp()) { 60 StmtNodeBuilder Bldr(*it, Tmp2, *currBldrCtx); 61 62 if (B->isAdditiveOp()) { 63 // If one of the operands is a location, conjure a symbol for the other 64 // one (offset) if it's unknown so that memory arithmetic always 65 // results in an ElementRegion. 66 // TODO: This can be removed after we enable history tracking with 67 // SymSymExpr. 68 unsigned Count = currBldrCtx->blockCount(); 69 if (isa<Loc>(LeftV) && 70 RHS->getType()->isIntegerType() && RightV.isUnknown()) { 71 RightV = svalBuilder.conjureSymbolVal(RHS, LCtx, RHS->getType(), 72 Count); 73 } 74 if (isa<Loc>(RightV) && 75 LHS->getType()->isIntegerType() && LeftV.isUnknown()) { 76 LeftV = svalBuilder.conjureSymbolVal(LHS, LCtx, LHS->getType(), 77 Count); 78 } 79 } 80 81 // Process non-assignments except commas or short-circuited 82 // logical expressions (LAnd and LOr). 83 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType()); 84 if (Result.isUnknown()) { 85 Bldr.generateNode(B, *it, state); 86 continue; 87 } 88 89 state = state->BindExpr(B, LCtx, Result); 90 Bldr.generateNode(B, *it, state); 91 continue; 92 } 93 94 assert (B->isCompoundAssignmentOp()); 95 96 switch (Op) { 97 default: 98 llvm_unreachable("Invalid opcode for compound assignment."); 99 case BO_MulAssign: Op = BO_Mul; break; 100 case BO_DivAssign: Op = BO_Div; break; 101 case BO_RemAssign: Op = BO_Rem; break; 102 case BO_AddAssign: Op = BO_Add; break; 103 case BO_SubAssign: Op = BO_Sub; break; 104 case BO_ShlAssign: Op = BO_Shl; break; 105 case BO_ShrAssign: Op = BO_Shr; break; 106 case BO_AndAssign: Op = BO_And; break; 107 case BO_XorAssign: Op = BO_Xor; break; 108 case BO_OrAssign: Op = BO_Or; break; 109 } 110 111 // Perform a load (the LHS). This performs the checks for 112 // null dereferences, and so on. 113 ExplodedNodeSet Tmp; 114 SVal location = LeftV; 115 evalLoad(Tmp, B, LHS, *it, state, location); 116 117 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; 118 ++I) { 119 120 state = (*I)->getState(); 121 const LocationContext *LCtx = (*I)->getLocationContext(); 122 SVal V = state->getSVal(LHS, LCtx); 123 124 // Get the computation type. 125 QualType CTy = 126 cast<CompoundAssignOperator>(B)->getComputationResultType(); 127 CTy = getContext().getCanonicalType(CTy); 128 129 QualType CLHSTy = 130 cast<CompoundAssignOperator>(B)->getComputationLHSType(); 131 CLHSTy = getContext().getCanonicalType(CLHSTy); 132 133 QualType LTy = getContext().getCanonicalType(LHS->getType()); 134 135 // Promote LHS. 136 V = svalBuilder.evalCast(V, CLHSTy, LTy); 137 138 // Compute the result of the operation. 139 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy), 140 B->getType(), CTy); 141 142 // EXPERIMENTAL: "Conjured" symbols. 143 // FIXME: Handle structs. 144 145 SVal LHSVal; 146 147 if (Result.isUnknown()) { 148 // The symbolic value is actually for the type of the left-hand side 149 // expression, not the computation type, as this is the value the 150 // LValue on the LHS will bind to. 151 LHSVal = svalBuilder.conjureSymbolVal(0, B->getRHS(), LCtx, LTy, 152 currBldrCtx->blockCount()); 153 // However, we need to convert the symbol to the computation type. 154 Result = svalBuilder.evalCast(LHSVal, CTy, LTy); 155 } 156 else { 157 // The left-hand side may bind to a different value then the 158 // computation type. 159 LHSVal = svalBuilder.evalCast(Result, LTy, CTy); 160 } 161 162 // In C++, assignment and compound assignment operators return an 163 // lvalue. 164 if (B->isGLValue()) 165 state = state->BindExpr(B, LCtx, location); 166 else 167 state = state->BindExpr(B, LCtx, Result); 168 169 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal); 170 } 171 } 172 173 // FIXME: postvisits eventually go in ::Visit() 174 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this); 175} 176 177void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred, 178 ExplodedNodeSet &Dst) { 179 180 CanQualType T = getContext().getCanonicalType(BE->getType()); 181 182 // Get the value of the block itself. 183 SVal V = svalBuilder.getBlockPointer(BE->getBlockDecl(), T, 184 Pred->getLocationContext()); 185 186 ProgramStateRef State = Pred->getState(); 187 188 // If we created a new MemRegion for the block, we should explicitly bind 189 // the captured variables. 190 if (const BlockDataRegion *BDR = 191 dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) { 192 193 BlockDataRegion::referenced_vars_iterator I = BDR->referenced_vars_begin(), 194 E = BDR->referenced_vars_end(); 195 196 for (; I != E; ++I) { 197 const MemRegion *capturedR = I.getCapturedRegion(); 198 const MemRegion *originalR = I.getOriginalRegion(); 199 if (capturedR != originalR) { 200 SVal originalV = State->getSVal(loc::MemRegionVal(originalR)); 201 State = State->bindLoc(loc::MemRegionVal(capturedR), originalV); 202 } 203 } 204 } 205 206 ExplodedNodeSet Tmp; 207 StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx); 208 Bldr.generateNode(BE, Pred, 209 State->BindExpr(BE, Pred->getLocationContext(), V), 210 0, ProgramPoint::PostLValueKind); 211 212 // FIXME: Move all post/pre visits to ::Visit(). 213 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this); 214} 215 216void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, 217 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 218 219 ExplodedNodeSet dstPreStmt; 220 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this); 221 222 if (CastE->getCastKind() == CK_LValueToRValue) { 223 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 224 I!=E; ++I) { 225 ExplodedNode *subExprNode = *I; 226 ProgramStateRef state = subExprNode->getState(); 227 const LocationContext *LCtx = subExprNode->getLocationContext(); 228 evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx)); 229 } 230 return; 231 } 232 233 // All other casts. 234 QualType T = CastE->getType(); 235 QualType ExTy = Ex->getType(); 236 237 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE)) 238 T = ExCast->getTypeAsWritten(); 239 240 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx); 241 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 242 I != E; ++I) { 243 244 Pred = *I; 245 246 switch (CastE->getCastKind()) { 247 case CK_LValueToRValue: 248 llvm_unreachable("LValueToRValue casts handled earlier."); 249 case CK_ToVoid: 250 continue; 251 // The analyzer doesn't do anything special with these casts, 252 // since it understands retain/release semantics already. 253 case CK_ARCProduceObject: 254 case CK_ARCConsumeObject: 255 case CK_ARCReclaimReturnedObject: 256 case CK_ARCExtendBlockObject: // Fall-through. 257 case CK_CopyAndAutoreleaseBlockObject: 258 // The analyser can ignore atomic casts for now, although some future 259 // checkers may want to make certain that you're not modifying the same 260 // value through atomic and nonatomic pointers. 261 case CK_AtomicToNonAtomic: 262 case CK_NonAtomicToAtomic: 263 // True no-ops. 264 case CK_NoOp: 265 case CK_FunctionToPointerDecay: { 266 // Copy the SVal of Ex to CastE. 267 ProgramStateRef state = Pred->getState(); 268 const LocationContext *LCtx = Pred->getLocationContext(); 269 SVal V = state->getSVal(Ex, LCtx); 270 state = state->BindExpr(CastE, LCtx, V); 271 Bldr.generateNode(CastE, Pred, state); 272 continue; 273 } 274 case CK_Dependent: 275 case CK_ArrayToPointerDecay: 276 case CK_BitCast: 277 case CK_IntegralCast: 278 case CK_NullToPointer: 279 case CK_IntegralToPointer: 280 case CK_PointerToIntegral: 281 case CK_PointerToBoolean: 282 case CK_IntegralToBoolean: 283 case CK_IntegralToFloating: 284 case CK_FloatingToIntegral: 285 case CK_FloatingToBoolean: 286 case CK_FloatingCast: 287 case CK_FloatingRealToComplex: 288 case CK_FloatingComplexToReal: 289 case CK_FloatingComplexToBoolean: 290 case CK_FloatingComplexCast: 291 case CK_FloatingComplexToIntegralComplex: 292 case CK_IntegralRealToComplex: 293 case CK_IntegralComplexToReal: 294 case CK_IntegralComplexToBoolean: 295 case CK_IntegralComplexCast: 296 case CK_IntegralComplexToFloatingComplex: 297 case CK_CPointerToObjCPointerCast: 298 case CK_BlockPointerToObjCPointerCast: 299 case CK_AnyPointerToBlockPointerCast: 300 case CK_ObjCObjectLValueCast: { 301 // Delegate to SValBuilder to process. 302 ProgramStateRef state = Pred->getState(); 303 const LocationContext *LCtx = Pred->getLocationContext(); 304 SVal V = state->getSVal(Ex, LCtx); 305 V = svalBuilder.evalCast(V, T, ExTy); 306 state = state->BindExpr(CastE, LCtx, V); 307 Bldr.generateNode(CastE, Pred, state); 308 continue; 309 } 310 case CK_DerivedToBase: 311 case CK_UncheckedDerivedToBase: { 312 // For DerivedToBase cast, delegate to the store manager. 313 ProgramStateRef state = Pred->getState(); 314 const LocationContext *LCtx = Pred->getLocationContext(); 315 SVal val = state->getSVal(Ex, LCtx); 316 val = getStoreManager().evalDerivedToBase(val, CastE); 317 state = state->BindExpr(CastE, LCtx, val); 318 Bldr.generateNode(CastE, Pred, state); 319 continue; 320 } 321 // Handle C++ dyn_cast. 322 case CK_Dynamic: { 323 ProgramStateRef state = Pred->getState(); 324 const LocationContext *LCtx = Pred->getLocationContext(); 325 SVal val = state->getSVal(Ex, LCtx); 326 327 // Compute the type of the result. 328 QualType resultType = CastE->getType(); 329 if (CastE->isGLValue()) 330 resultType = getContext().getPointerType(resultType); 331 332 bool Failed = false; 333 334 // Check if the value being cast evaluates to 0. 335 if (val.isZeroConstant()) 336 Failed = true; 337 // Else, evaluate the cast. 338 else 339 val = getStoreManager().evalDynamicCast(val, T, Failed); 340 341 if (Failed) { 342 if (T->isReferenceType()) { 343 // A bad_cast exception is thrown if input value is a reference. 344 // Currently, we model this, by generating a sink. 345 Bldr.generateSink(CastE, Pred, state); 346 continue; 347 } else { 348 // If the cast fails on a pointer, bind to 0. 349 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 350 } 351 } else { 352 // If we don't know if the cast succeeded, conjure a new symbol. 353 if (val.isUnknown()) { 354 DefinedOrUnknownSVal NewSym = 355 svalBuilder.conjureSymbolVal(0, CastE, LCtx, resultType, 356 currBldrCtx->blockCount()); 357 state = state->BindExpr(CastE, LCtx, NewSym); 358 } else 359 // Else, bind to the derived region value. 360 state = state->BindExpr(CastE, LCtx, val); 361 } 362 Bldr.generateNode(CastE, Pred, state); 363 continue; 364 } 365 // Various C++ casts that are not handled yet. 366 case CK_ToUnion: 367 case CK_BaseToDerived: 368 case CK_NullToMemberPointer: 369 case CK_BaseToDerivedMemberPointer: 370 case CK_DerivedToBaseMemberPointer: 371 case CK_ReinterpretMemberPointer: 372 case CK_UserDefinedConversion: 373 case CK_ConstructorConversion: 374 case CK_VectorSplat: 375 case CK_MemberPointerToBoolean: 376 case CK_LValueBitCast: { 377 // Recover some path-sensitivty by conjuring a new value. 378 QualType resultType = CastE->getType(); 379 if (CastE->isGLValue()) 380 resultType = getContext().getPointerType(resultType); 381 const LocationContext *LCtx = Pred->getLocationContext(); 382 SVal result = svalBuilder.conjureSymbolVal(0, CastE, LCtx, 383 resultType, 384 currBldrCtx->blockCount()); 385 ProgramStateRef state = Pred->getState()->BindExpr(CastE, LCtx, 386 result); 387 Bldr.generateNode(CastE, Pred, state); 388 continue; 389 } 390 } 391 } 392} 393 394void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 395 ExplodedNode *Pred, 396 ExplodedNodeSet &Dst) { 397 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 398 399 const InitListExpr *ILE 400 = cast<InitListExpr>(CL->getInitializer()->IgnoreParens()); 401 402 ProgramStateRef state = Pred->getState(); 403 SVal ILV = state->getSVal(ILE, Pred->getLocationContext()); 404 const LocationContext *LC = Pred->getLocationContext(); 405 state = state->bindCompoundLiteral(CL, LC, ILV); 406 407 // Compound literal expressions are a GNU extension in C++. 408 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, 409 // and like temporary objects created by the functional notation T() 410 // CLs are destroyed at the end of the containing full-expression. 411 // HOWEVER, an rvalue of array type is not something the analyzer can 412 // reason about, since we expect all regions to be wrapped in Locs. 413 // So we treat array CLs as lvalues as well, knowing that they will decay 414 // to pointers as soon as they are used. 415 if (CL->isGLValue() || CL->getType()->isArrayType()) 416 B.generateNode(CL, Pred, state->BindExpr(CL, LC, state->getLValue(CL, LC))); 417 else 418 B.generateNode(CL, Pred, state->BindExpr(CL, LC, ILV)); 419} 420 421void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 422 ExplodedNodeSet &Dst) { 423 424 // FIXME: static variables may have an initializer, but the second 425 // time a function is called those values may not be current. 426 // This may need to be reflected in the CFG. 427 428 // Assumption: The CFG has one DeclStmt per Decl. 429 const Decl *D = *DS->decl_begin(); 430 431 if (!D || !isa<VarDecl>(D)) { 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 const VarDecl *VD = dyn_cast<VarDecl>(D); 443 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 444 I!=E; ++I) { 445 ExplodedNode *N = *I; 446 ProgramStateRef state = N->getState(); 447 448 // Decls without InitExpr are not initialized explicitly. 449 const LocationContext *LC = N->getLocationContext(); 450 451 if (const Expr *InitEx = VD->getInit()) { 452 SVal InitVal = state->getSVal(InitEx, LC); 453 454 if (InitVal == state->getLValue(VD, LC) || 455 (VD->getType()->isArrayType() && 456 isa<CXXConstructExpr>(InitEx->IgnoreImplicit()))) { 457 // We constructed the object directly in the variable. 458 // No need to bind anything. 459 B.generateNode(DS, N, state); 460 } else { 461 // We bound the temp obj region to the CXXConstructExpr. Now recover 462 // the lazy compound value when the variable is not a reference. 463 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 464 !VD->getType()->isReferenceType() && isa<loc::MemRegionVal>(InitVal)){ 465 InitVal = state->getSVal(cast<loc::MemRegionVal>(InitVal).getRegion()); 466 assert(isa<nonloc::LazyCompoundVal>(InitVal)); 467 } 468 469 // Recover some path-sensitivity if a scalar value evaluated to 470 // UnknownVal. 471 if (InitVal.isUnknown()) { 472 QualType Ty = InitEx->getType(); 473 if (InitEx->isGLValue()) { 474 Ty = getContext().getPointerType(Ty); 475 } 476 477 InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, 478 currBldrCtx->blockCount()); 479 } 480 B.takeNodes(N); 481 ExplodedNodeSet Dst2; 482 evalBind(Dst2, DS, N, state->getLValue(VD, LC), InitVal, true); 483 B.addNodes(Dst2); 484 } 485 } 486 else { 487 B.generateNode(DS, N, state); 488 } 489 } 490} 491 492void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 493 ExplodedNodeSet &Dst) { 494 assert(B->getOpcode() == BO_LAnd || 495 B->getOpcode() == BO_LOr); 496 497 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 498 ProgramStateRef state = Pred->getState(); 499 500 ExplodedNode *N = Pred; 501 while (!isa<BlockEntrance>(N->getLocation())) { 502 ProgramPoint P = N->getLocation(); 503 assert(isa<PreStmt>(P)|| isa<PreStmtPurgeDeadSymbols>(P)); 504 (void) P; 505 assert(N->pred_size() == 1); 506 N = *N->pred_begin(); 507 } 508 assert(N->pred_size() == 1); 509 N = *N->pred_begin(); 510 BlockEdge BE = cast<BlockEdge>(N->getLocation()); 511 SVal X; 512 513 // Determine the value of the expression by introspecting how we 514 // got this location in the CFG. This requires looking at the previous 515 // block we were in and what kind of control-flow transfer was involved. 516 const CFGBlock *SrcBlock = BE.getSrc(); 517 // The only terminator (if there is one) that makes sense is a logical op. 518 CFGTerminator T = SrcBlock->getTerminator(); 519 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { 520 (void) Term; 521 assert(Term->isLogicalOp()); 522 assert(SrcBlock->succ_size() == 2); 523 // Did we take the true or false branch? 524 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; 525 X = svalBuilder.makeIntVal(constant, B->getType()); 526 } 527 else { 528 // If there is no terminator, by construction the last statement 529 // in SrcBlock is the value of the enclosing expression. 530 // However, we still need to constrain that value to be 0 or 1. 531 assert(!SrcBlock->empty()); 532 CFGStmt Elem = cast<CFGStmt>(*SrcBlock->rbegin()); 533 const Expr *RHS = cast<Expr>(Elem.getStmt()); 534 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); 535 536 DefinedOrUnknownSVal DefinedRHS = cast<DefinedOrUnknownSVal>(RHSVal); 537 ProgramStateRef StTrue, StFalse; 538 llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); 539 if (StTrue) { 540 if (StFalse) { 541 // We can't constrain the value to 0 or 1; the best we can do is a cast. 542 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); 543 } else { 544 // The value is known to be true. 545 X = getSValBuilder().makeIntVal(1, B->getType()); 546 } 547 } else { 548 // The value is known to be false. 549 assert(StFalse && "Infeasible path!"); 550 X = getSValBuilder().makeIntVal(0, B->getType()); 551 } 552 } 553 554 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); 555} 556 557void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 558 ExplodedNode *Pred, 559 ExplodedNodeSet &Dst) { 560 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 561 562 ProgramStateRef state = Pred->getState(); 563 const LocationContext *LCtx = Pred->getLocationContext(); 564 QualType T = getContext().getCanonicalType(IE->getType()); 565 unsigned NumInitElements = IE->getNumInits(); 566 567 if (T->isArrayType() || T->isRecordType() || T->isVectorType()) { 568 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 569 570 // Handle base case where the initializer has no elements. 571 // e.g: static int* myArray[] = {}; 572 if (NumInitElements == 0) { 573 SVal V = svalBuilder.makeCompoundVal(T, vals); 574 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 575 return; 576 } 577 578 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 579 ei = IE->rend(); it != ei; ++it) { 580 vals = getBasicVals().consVals(state->getSVal(cast<Expr>(*it), LCtx), 581 vals); 582 } 583 584 B.generateNode(IE, Pred, 585 state->BindExpr(IE, LCtx, 586 svalBuilder.makeCompoundVal(T, vals))); 587 return; 588 } 589 590 // Handle scalars: int{5} and int{}. 591 assert(NumInitElements <= 1); 592 593 SVal V; 594 if (NumInitElements == 0) 595 V = getSValBuilder().makeZeroVal(T); 596 else 597 V = state->getSVal(IE->getInit(0), LCtx); 598 599 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 600} 601 602void ExprEngine::VisitGuardedExpr(const Expr *Ex, 603 const Expr *L, 604 const Expr *R, 605 ExplodedNode *Pred, 606 ExplodedNodeSet &Dst) { 607 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 608 ProgramStateRef state = Pred->getState(); 609 const LocationContext *LCtx = Pred->getLocationContext(); 610 const CFGBlock *SrcBlock = 0; 611 612 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { 613 ProgramPoint PP = N->getLocation(); 614 if (isa<PreStmtPurgeDeadSymbols>(PP) || isa<BlockEntrance>(PP)) { 615 assert(N->pred_size() == 1); 616 continue; 617 } 618 SrcBlock = cast<BlockEdge>(&PP)->getSrc(); 619 break; 620 } 621 622 // Find the last expression in the predecessor block. That is the 623 // expression that is used for the value of the ternary expression. 624 bool hasValue = false; 625 SVal V; 626 627 for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), 628 E = SrcBlock->rend(); I != E; ++I) { 629 CFGElement CE = *I; 630 if (CFGStmt *CS = dyn_cast<CFGStmt>(&CE)) { 631 const Expr *ValEx = cast<Expr>(CS->getStmt()); 632 hasValue = true; 633 V = state->getSVal(ValEx, LCtx); 634 break; 635 } 636 } 637 638 assert(hasValue); 639 (void) hasValue; 640 641 // Generate a new node with the binding from the appropriate path. 642 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); 643} 644 645void ExprEngine:: 646VisitOffsetOfExpr(const OffsetOfExpr *OOE, 647 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 648 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 649 APSInt IV; 650 if (OOE->EvaluateAsInt(IV, getContext())) { 651 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 652 assert(OOE->getType()->isIntegerType()); 653 assert(IV.isSigned() == OOE->getType()->isSignedIntegerOrEnumerationType()); 654 SVal X = svalBuilder.makeIntVal(IV); 655 B.generateNode(OOE, Pred, 656 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 657 X)); 658 } 659 // FIXME: Handle the case where __builtin_offsetof is not a constant. 660} 661 662 663void ExprEngine:: 664VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 665 ExplodedNode *Pred, 666 ExplodedNodeSet &Dst) { 667 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 668 669 QualType T = Ex->getTypeOfArgument(); 670 671 if (Ex->getKind() == UETT_SizeOf) { 672 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 673 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 674 675 // FIXME: Add support for VLA type arguments and VLA expressions. 676 // When that happens, we should probably refactor VLASizeChecker's code. 677 return; 678 } 679 else if (T->getAs<ObjCObjectType>()) { 680 // Some code tries to take the sizeof an ObjCObjectType, relying that 681 // the compiler has laid out its representation. Just report Unknown 682 // for these. 683 return; 684 } 685 } 686 687 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 688 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 689 690 ProgramStateRef state = Pred->getState(); 691 state = state->BindExpr(Ex, Pred->getLocationContext(), 692 svalBuilder.makeIntVal(amt.getQuantity(), 693 Ex->getType())); 694 Bldr.generateNode(Ex, Pred, state); 695} 696 697void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 698 ExplodedNode *Pred, 699 ExplodedNodeSet &Dst) { 700 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 701 switch (U->getOpcode()) { 702 default: { 703 Bldr.takeNodes(Pred); 704 ExplodedNodeSet Tmp; 705 VisitIncrementDecrementOperator(U, Pred, Tmp); 706 Bldr.addNodes(Tmp); 707 } 708 break; 709 case UO_Real: { 710 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 711 712 // FIXME: We don't have complex SValues yet. 713 if (Ex->getType()->isAnyComplexType()) { 714 // Just report "Unknown." 715 break; 716 } 717 718 // For all other types, UO_Real is an identity operation. 719 assert (U->getType() == Ex->getType()); 720 ProgramStateRef state = Pred->getState(); 721 const LocationContext *LCtx = Pred->getLocationContext(); 722 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 723 state->getSVal(Ex, LCtx))); 724 break; 725 } 726 727 case UO_Imag: { 728 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 729 // FIXME: We don't have complex SValues yet. 730 if (Ex->getType()->isAnyComplexType()) { 731 // Just report "Unknown." 732 break; 733 } 734 // For all other types, UO_Imag returns 0. 735 ProgramStateRef state = Pred->getState(); 736 const LocationContext *LCtx = Pred->getLocationContext(); 737 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 738 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, X)); 739 break; 740 } 741 742 case UO_Plus: 743 assert(!U->isGLValue()); 744 // FALL-THROUGH. 745 case UO_Deref: 746 case UO_AddrOf: 747 case UO_Extension: { 748 // FIXME: We can probably just have some magic in Environment::getSVal() 749 // that propagates values, instead of creating a new node here. 750 // 751 // Unary "+" is a no-op, similar to a parentheses. We still have places 752 // where it may be a block-level expression, so we need to 753 // generate an extra node that just propagates the value of the 754 // subexpression. 755 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 756 ProgramStateRef state = Pred->getState(); 757 const LocationContext *LCtx = Pred->getLocationContext(); 758 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 759 state->getSVal(Ex, LCtx))); 760 break; 761 } 762 763 case UO_LNot: 764 case UO_Minus: 765 case UO_Not: { 766 assert (!U->isGLValue()); 767 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 768 ProgramStateRef state = Pred->getState(); 769 const LocationContext *LCtx = Pred->getLocationContext(); 770 771 // Get the value of the subexpression. 772 SVal V = state->getSVal(Ex, LCtx); 773 774 if (V.isUnknownOrUndef()) { 775 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, V)); 776 break; 777 } 778 779 switch (U->getOpcode()) { 780 default: 781 llvm_unreachable("Invalid Opcode."); 782 case UO_Not: 783 // FIXME: Do we need to handle promotions? 784 state = state->BindExpr(U, LCtx, evalComplement(cast<NonLoc>(V))); 785 break; 786 case UO_Minus: 787 // FIXME: Do we need to handle promotions? 788 state = state->BindExpr(U, LCtx, evalMinus(cast<NonLoc>(V))); 789 break; 790 case UO_LNot: 791 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 792 // 793 // Note: technically we do "E == 0", but this is the same in the 794 // transfer functions as "0 == E". 795 SVal Result; 796 if (isa<Loc>(V)) { 797 Loc X = svalBuilder.makeNull(); 798 Result = evalBinOp(state, BO_EQ, cast<Loc>(V), X, 799 U->getType()); 800 } 801 else { 802 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 803 Result = evalBinOp(state, BO_EQ, cast<NonLoc>(V), X, 804 U->getType()); 805 } 806 807 state = state->BindExpr(U, LCtx, Result); 808 break; 809 } 810 Bldr.generateNode(U, Pred, state); 811 break; 812 } 813 } 814 815} 816 817void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 818 ExplodedNode *Pred, 819 ExplodedNodeSet &Dst) { 820 // Handle ++ and -- (both pre- and post-increment). 821 assert (U->isIncrementDecrementOp()); 822 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 823 824 const LocationContext *LCtx = Pred->getLocationContext(); 825 ProgramStateRef state = Pred->getState(); 826 SVal loc = state->getSVal(Ex, LCtx); 827 828 // Perform a load. 829 ExplodedNodeSet Tmp; 830 evalLoad(Tmp, U, Ex, Pred, state, loc); 831 832 ExplodedNodeSet Dst2; 833 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx); 834 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 835 836 state = (*I)->getState(); 837 assert(LCtx == (*I)->getLocationContext()); 838 SVal V2_untested = state->getSVal(Ex, LCtx); 839 840 // Propagate unknown and undefined values. 841 if (V2_untested.isUnknownOrUndef()) { 842 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 843 continue; 844 } 845 DefinedSVal V2 = cast<DefinedSVal>(V2_untested); 846 847 // Handle all other values. 848 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 849 850 // If the UnaryOperator has non-location type, use its type to create the 851 // constant value. If the UnaryOperator has location type, create the 852 // constant with int type and pointer width. 853 SVal RHS; 854 855 if (U->getType()->isAnyPointerType()) 856 RHS = svalBuilder.makeArrayIndex(1); 857 else 858 RHS = svalBuilder.makeIntVal(1, U->getType()); 859 860 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 861 862 // Conjure a new symbol if necessary to recover precision. 863 if (Result.isUnknown()){ 864 DefinedOrUnknownSVal SymVal = 865 svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 866 Result = SymVal; 867 868 // If the value is a location, ++/-- should always preserve 869 // non-nullness. Check if the original value was non-null, and if so 870 // propagate that constraint. 871 if (Loc::isLocType(U->getType())) { 872 DefinedOrUnknownSVal Constraint = 873 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 874 875 if (!state->assume(Constraint, true)) { 876 // It isn't feasible for the original value to be null. 877 // Propagate this constraint. 878 Constraint = svalBuilder.evalEQ(state, SymVal, 879 svalBuilder.makeZeroVal(U->getType())); 880 881 882 state = state->assume(Constraint, false); 883 assert(state); 884 } 885 } 886 } 887 888 // Since the lvalue-to-rvalue conversion is explicit in the AST, 889 // we bind an l-value if the operator is prefix and an lvalue (in C++). 890 if (U->isGLValue()) 891 state = state->BindExpr(U, LCtx, loc); 892 else 893 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 894 895 // Perform the store. 896 Bldr.takeNodes(*I); 897 ExplodedNodeSet Dst3; 898 evalStore(Dst3, U, U, *I, state, loc, Result); 899 Bldr.addNodes(Dst3); 900 } 901 Dst.insert(Dst2); 902} 903