ExprEngineC.cpp revision 243830
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 ProgramStateRef state = Pred->getState(); 246 const LocationContext *LCtx = Pred->getLocationContext(); 247 248 switch (CastE->getCastKind()) { 249 case CK_LValueToRValue: 250 llvm_unreachable("LValueToRValue casts handled earlier."); 251 case CK_ToVoid: 252 continue; 253 // The analyzer doesn't do anything special with these casts, 254 // since it understands retain/release semantics already. 255 case CK_ARCProduceObject: 256 case CK_ARCConsumeObject: 257 case CK_ARCReclaimReturnedObject: 258 case CK_ARCExtendBlockObject: // Fall-through. 259 case CK_CopyAndAutoreleaseBlockObject: 260 // The analyser can ignore atomic casts for now, although some future 261 // checkers may want to make certain that you're not modifying the same 262 // value through atomic and nonatomic pointers. 263 case CK_AtomicToNonAtomic: 264 case CK_NonAtomicToAtomic: 265 // True no-ops. 266 case CK_NoOp: 267 case CK_ConstructorConversion: 268 case CK_UserDefinedConversion: 269 case CK_FunctionToPointerDecay: 270 case CK_BuiltinFnToFnPtr: { 271 // Copy the SVal of Ex to CastE. 272 ProgramStateRef state = Pred->getState(); 273 const LocationContext *LCtx = Pred->getLocationContext(); 274 SVal V = state->getSVal(Ex, LCtx); 275 state = state->BindExpr(CastE, LCtx, V); 276 Bldr.generateNode(CastE, Pred, state); 277 continue; 278 } 279 case CK_MemberPointerToBoolean: 280 // FIXME: For now, member pointers are represented by void *. 281 // FALLTHROUGH 282 case CK_Dependent: 283 case CK_ArrayToPointerDecay: 284 case CK_BitCast: 285 case CK_IntegralCast: 286 case CK_NullToPointer: 287 case CK_IntegralToPointer: 288 case CK_PointerToIntegral: 289 case CK_PointerToBoolean: 290 case CK_IntegralToBoolean: 291 case CK_IntegralToFloating: 292 case CK_FloatingToIntegral: 293 case CK_FloatingToBoolean: 294 case CK_FloatingCast: 295 case CK_FloatingRealToComplex: 296 case CK_FloatingComplexToReal: 297 case CK_FloatingComplexToBoolean: 298 case CK_FloatingComplexCast: 299 case CK_FloatingComplexToIntegralComplex: 300 case CK_IntegralRealToComplex: 301 case CK_IntegralComplexToReal: 302 case CK_IntegralComplexToBoolean: 303 case CK_IntegralComplexCast: 304 case CK_IntegralComplexToFloatingComplex: 305 case CK_CPointerToObjCPointerCast: 306 case CK_BlockPointerToObjCPointerCast: 307 case CK_AnyPointerToBlockPointerCast: 308 case CK_ObjCObjectLValueCast: { 309 // Delegate to SValBuilder to process. 310 SVal V = state->getSVal(Ex, LCtx); 311 V = svalBuilder.evalCast(V, T, ExTy); 312 state = state->BindExpr(CastE, LCtx, V); 313 Bldr.generateNode(CastE, Pred, state); 314 continue; 315 } 316 case CK_DerivedToBase: 317 case CK_UncheckedDerivedToBase: { 318 // For DerivedToBase cast, delegate to the store manager. 319 SVal val = state->getSVal(Ex, LCtx); 320 val = getStoreManager().evalDerivedToBase(val, CastE); 321 state = state->BindExpr(CastE, LCtx, val); 322 Bldr.generateNode(CastE, Pred, state); 323 continue; 324 } 325 // Handle C++ dyn_cast. 326 case CK_Dynamic: { 327 SVal val = state->getSVal(Ex, LCtx); 328 329 // Compute the type of the result. 330 QualType resultType = CastE->getType(); 331 if (CastE->isGLValue()) 332 resultType = getContext().getPointerType(resultType); 333 334 bool Failed = false; 335 336 // Check if the value being cast evaluates to 0. 337 if (val.isZeroConstant()) 338 Failed = true; 339 // Else, evaluate the cast. 340 else 341 val = getStoreManager().evalDynamicCast(val, T, Failed); 342 343 if (Failed) { 344 if (T->isReferenceType()) { 345 // A bad_cast exception is thrown if input value is a reference. 346 // Currently, we model this, by generating a sink. 347 Bldr.generateSink(CastE, Pred, state); 348 continue; 349 } else { 350 // If the cast fails on a pointer, bind to 0. 351 state = state->BindExpr(CastE, LCtx, svalBuilder.makeNull()); 352 } 353 } else { 354 // If we don't know if the cast succeeded, conjure a new symbol. 355 if (val.isUnknown()) { 356 DefinedOrUnknownSVal NewSym = 357 svalBuilder.conjureSymbolVal(0, CastE, LCtx, resultType, 358 currBldrCtx->blockCount()); 359 state = state->BindExpr(CastE, LCtx, NewSym); 360 } else 361 // Else, bind to the derived region value. 362 state = state->BindExpr(CastE, LCtx, val); 363 } 364 Bldr.generateNode(CastE, Pred, state); 365 continue; 366 } 367 case CK_NullToMemberPointer: { 368 // FIXME: For now, member pointers are represented by void *. 369 SVal V = svalBuilder.makeIntValWithPtrWidth(0, true); 370 state = state->BindExpr(CastE, LCtx, V); 371 Bldr.generateNode(CastE, Pred, state); 372 continue; 373 } 374 // Various C++ casts that are not handled yet. 375 case CK_ToUnion: 376 case CK_BaseToDerived: 377 case CK_BaseToDerivedMemberPointer: 378 case CK_DerivedToBaseMemberPointer: 379 case CK_ReinterpretMemberPointer: 380 case CK_VectorSplat: 381 case CK_LValueBitCast: { 382 // Recover some path-sensitivty by conjuring a new value. 383 QualType resultType = CastE->getType(); 384 if (CastE->isGLValue()) 385 resultType = getContext().getPointerType(resultType); 386 SVal result = svalBuilder.conjureSymbolVal(0, CastE, LCtx, 387 resultType, 388 currBldrCtx->blockCount()); 389 state = state->BindExpr(CastE, LCtx, result); 390 Bldr.generateNode(CastE, Pred, state); 391 continue; 392 } 393 } 394 } 395} 396 397void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 398 ExplodedNode *Pred, 399 ExplodedNodeSet &Dst) { 400 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 401 402 const InitListExpr *ILE 403 = cast<InitListExpr>(CL->getInitializer()->IgnoreParens()); 404 405 ProgramStateRef state = Pred->getState(); 406 SVal ILV = state->getSVal(ILE, Pred->getLocationContext()); 407 const LocationContext *LC = Pred->getLocationContext(); 408 state = state->bindCompoundLiteral(CL, LC, ILV); 409 410 // Compound literal expressions are a GNU extension in C++. 411 // Unlike in C, where CLs are lvalues, in C++ CLs are prvalues, 412 // and like temporary objects created by the functional notation T() 413 // CLs are destroyed at the end of the containing full-expression. 414 // HOWEVER, an rvalue of array type is not something the analyzer can 415 // reason about, since we expect all regions to be wrapped in Locs. 416 // So we treat array CLs as lvalues as well, knowing that they will decay 417 // to pointers as soon as they are used. 418 if (CL->isGLValue() || CL->getType()->isArrayType()) 419 B.generateNode(CL, Pred, state->BindExpr(CL, LC, state->getLValue(CL, LC))); 420 else 421 B.generateNode(CL, Pred, state->BindExpr(CL, LC, ILV)); 422} 423 424void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 425 ExplodedNodeSet &Dst) { 426 427 // FIXME: static variables may have an initializer, but the second 428 // time a function is called those values may not be current. 429 // This may need to be reflected in the CFG. 430 431 // Assumption: The CFG has one DeclStmt per Decl. 432 const Decl *D = *DS->decl_begin(); 433 434 if (!D || !isa<VarDecl>(D)) { 435 //TODO:AZ: remove explicit insertion after refactoring is done. 436 Dst.insert(Pred); 437 return; 438 } 439 440 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 441 ExplodedNodeSet dstPreVisit; 442 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 443 444 StmtNodeBuilder B(dstPreVisit, Dst, *currBldrCtx); 445 const VarDecl *VD = dyn_cast<VarDecl>(D); 446 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 447 I!=E; ++I) { 448 ExplodedNode *N = *I; 449 ProgramStateRef state = N->getState(); 450 451 // Decls without InitExpr are not initialized explicitly. 452 const LocationContext *LC = N->getLocationContext(); 453 454 if (const Expr *InitEx = VD->getInit()) { 455 SVal InitVal = state->getSVal(InitEx, LC); 456 457 if (InitVal == state->getLValue(VD, LC) || 458 (VD->getType()->isArrayType() && 459 isa<CXXConstructExpr>(InitEx->IgnoreImplicit()))) { 460 // We constructed the object directly in the variable. 461 // No need to bind anything. 462 B.generateNode(DS, N, state); 463 } else { 464 // We bound the temp obj region to the CXXConstructExpr. Now recover 465 // the lazy compound value when the variable is not a reference. 466 if (AMgr.getLangOpts().CPlusPlus && VD->getType()->isRecordType() && 467 !VD->getType()->isReferenceType() && isa<loc::MemRegionVal>(InitVal)){ 468 InitVal = state->getSVal(cast<loc::MemRegionVal>(InitVal).getRegion()); 469 assert(isa<nonloc::LazyCompoundVal>(InitVal)); 470 } 471 472 // Recover some path-sensitivity if a scalar value evaluated to 473 // UnknownVal. 474 if (InitVal.isUnknown()) { 475 QualType Ty = InitEx->getType(); 476 if (InitEx->isGLValue()) { 477 Ty = getContext().getPointerType(Ty); 478 } 479 480 InitVal = svalBuilder.conjureSymbolVal(0, InitEx, LC, Ty, 481 currBldrCtx->blockCount()); 482 } 483 B.takeNodes(N); 484 ExplodedNodeSet Dst2; 485 evalBind(Dst2, DS, N, state->getLValue(VD, LC), InitVal, true); 486 B.addNodes(Dst2); 487 } 488 } 489 else { 490 B.generateNode(DS, N, state); 491 } 492 } 493} 494 495void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 496 ExplodedNodeSet &Dst) { 497 assert(B->getOpcode() == BO_LAnd || 498 B->getOpcode() == BO_LOr); 499 500 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 501 ProgramStateRef state = Pred->getState(); 502 503 ExplodedNode *N = Pred; 504 while (!isa<BlockEntrance>(N->getLocation())) { 505 ProgramPoint P = N->getLocation(); 506 assert(isa<PreStmt>(P)|| isa<PreStmtPurgeDeadSymbols>(P)); 507 (void) P; 508 assert(N->pred_size() == 1); 509 N = *N->pred_begin(); 510 } 511 assert(N->pred_size() == 1); 512 N = *N->pred_begin(); 513 BlockEdge BE = cast<BlockEdge>(N->getLocation()); 514 SVal X; 515 516 // Determine the value of the expression by introspecting how we 517 // got this location in the CFG. This requires looking at the previous 518 // block we were in and what kind of control-flow transfer was involved. 519 const CFGBlock *SrcBlock = BE.getSrc(); 520 // The only terminator (if there is one) that makes sense is a logical op. 521 CFGTerminator T = SrcBlock->getTerminator(); 522 if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) { 523 (void) Term; 524 assert(Term->isLogicalOp()); 525 assert(SrcBlock->succ_size() == 2); 526 // Did we take the true or false branch? 527 unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0; 528 X = svalBuilder.makeIntVal(constant, B->getType()); 529 } 530 else { 531 // If there is no terminator, by construction the last statement 532 // in SrcBlock is the value of the enclosing expression. 533 // However, we still need to constrain that value to be 0 or 1. 534 assert(!SrcBlock->empty()); 535 CFGStmt Elem = cast<CFGStmt>(*SrcBlock->rbegin()); 536 const Expr *RHS = cast<Expr>(Elem.getStmt()); 537 SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext()); 538 539 DefinedOrUnknownSVal DefinedRHS = cast<DefinedOrUnknownSVal>(RHSVal); 540 ProgramStateRef StTrue, StFalse; 541 llvm::tie(StTrue, StFalse) = N->getState()->assume(DefinedRHS); 542 if (StTrue) { 543 if (StFalse) { 544 // We can't constrain the value to 0 or 1; the best we can do is a cast. 545 X = getSValBuilder().evalCast(RHSVal, B->getType(), RHS->getType()); 546 } else { 547 // The value is known to be true. 548 X = getSValBuilder().makeIntVal(1, B->getType()); 549 } 550 } else { 551 // The value is known to be false. 552 assert(StFalse && "Infeasible path!"); 553 X = getSValBuilder().makeIntVal(0, B->getType()); 554 } 555 } 556 557 Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X)); 558} 559 560void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 561 ExplodedNode *Pred, 562 ExplodedNodeSet &Dst) { 563 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 564 565 ProgramStateRef state = Pred->getState(); 566 const LocationContext *LCtx = Pred->getLocationContext(); 567 QualType T = getContext().getCanonicalType(IE->getType()); 568 unsigned NumInitElements = IE->getNumInits(); 569 570 if (T->isArrayType() || T->isRecordType() || T->isVectorType() || 571 T->isAnyComplexType()) { 572 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 573 574 // Handle base case where the initializer has no elements. 575 // e.g: static int* myArray[] = {}; 576 if (NumInitElements == 0) { 577 SVal V = svalBuilder.makeCompoundVal(T, vals); 578 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 579 return; 580 } 581 582 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 583 ei = IE->rend(); it != ei; ++it) { 584 vals = getBasicVals().consVals(state->getSVal(cast<Expr>(*it), LCtx), 585 vals); 586 } 587 588 B.generateNode(IE, Pred, 589 state->BindExpr(IE, LCtx, 590 svalBuilder.makeCompoundVal(T, vals))); 591 return; 592 } 593 594 // Handle scalars: int{5} and int{}. 595 assert(NumInitElements <= 1); 596 597 SVal V; 598 if (NumInitElements == 0) 599 V = getSValBuilder().makeZeroVal(T); 600 else 601 V = state->getSVal(IE->getInit(0), LCtx); 602 603 B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V)); 604} 605 606void ExprEngine::VisitGuardedExpr(const Expr *Ex, 607 const Expr *L, 608 const Expr *R, 609 ExplodedNode *Pred, 610 ExplodedNodeSet &Dst) { 611 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 612 ProgramStateRef state = Pred->getState(); 613 const LocationContext *LCtx = Pred->getLocationContext(); 614 const CFGBlock *SrcBlock = 0; 615 616 for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) { 617 ProgramPoint PP = N->getLocation(); 618 if (isa<PreStmtPurgeDeadSymbols>(PP) || isa<BlockEntrance>(PP)) { 619 assert(N->pred_size() == 1); 620 continue; 621 } 622 SrcBlock = cast<BlockEdge>(&PP)->getSrc(); 623 break; 624 } 625 626 // Find the last expression in the predecessor block. That is the 627 // expression that is used for the value of the ternary expression. 628 bool hasValue = false; 629 SVal V; 630 631 for (CFGBlock::const_reverse_iterator I = SrcBlock->rbegin(), 632 E = SrcBlock->rend(); I != E; ++I) { 633 CFGElement CE = *I; 634 if (CFGStmt *CS = dyn_cast<CFGStmt>(&CE)) { 635 const Expr *ValEx = cast<Expr>(CS->getStmt()); 636 hasValue = true; 637 V = state->getSVal(ValEx, LCtx); 638 break; 639 } 640 } 641 642 assert(hasValue); 643 (void) hasValue; 644 645 // Generate a new node with the binding from the appropriate path. 646 B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true)); 647} 648 649void ExprEngine:: 650VisitOffsetOfExpr(const OffsetOfExpr *OOE, 651 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 652 StmtNodeBuilder B(Pred, Dst, *currBldrCtx); 653 APSInt IV; 654 if (OOE->EvaluateAsInt(IV, getContext())) { 655 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 656 assert(OOE->getType()->isIntegerType()); 657 assert(IV.isSigned() == OOE->getType()->isSignedIntegerOrEnumerationType()); 658 SVal X = svalBuilder.makeIntVal(IV); 659 B.generateNode(OOE, Pred, 660 Pred->getState()->BindExpr(OOE, Pred->getLocationContext(), 661 X)); 662 } 663 // FIXME: Handle the case where __builtin_offsetof is not a constant. 664} 665 666 667void ExprEngine:: 668VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 669 ExplodedNode *Pred, 670 ExplodedNodeSet &Dst) { 671 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 672 673 QualType T = Ex->getTypeOfArgument(); 674 675 if (Ex->getKind() == UETT_SizeOf) { 676 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 677 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 678 679 // FIXME: Add support for VLA type arguments and VLA expressions. 680 // When that happens, we should probably refactor VLASizeChecker's code. 681 return; 682 } 683 else if (T->getAs<ObjCObjectType>()) { 684 // Some code tries to take the sizeof an ObjCObjectType, relying that 685 // the compiler has laid out its representation. Just report Unknown 686 // for these. 687 return; 688 } 689 } 690 691 APSInt Value = Ex->EvaluateKnownConstInt(getContext()); 692 CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue()); 693 694 ProgramStateRef state = Pred->getState(); 695 state = state->BindExpr(Ex, Pred->getLocationContext(), 696 svalBuilder.makeIntVal(amt.getQuantity(), 697 Ex->getType())); 698 Bldr.generateNode(Ex, Pred, state); 699} 700 701void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 702 ExplodedNode *Pred, 703 ExplodedNodeSet &Dst) { 704 StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx); 705 switch (U->getOpcode()) { 706 default: { 707 Bldr.takeNodes(Pred); 708 ExplodedNodeSet Tmp; 709 VisitIncrementDecrementOperator(U, Pred, Tmp); 710 Bldr.addNodes(Tmp); 711 } 712 break; 713 case UO_Real: { 714 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 715 716 // FIXME: We don't have complex SValues yet. 717 if (Ex->getType()->isAnyComplexType()) { 718 // Just report "Unknown." 719 break; 720 } 721 722 // For all other types, UO_Real is an identity operation. 723 assert (U->getType() == Ex->getType()); 724 ProgramStateRef state = Pred->getState(); 725 const LocationContext *LCtx = Pred->getLocationContext(); 726 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 727 state->getSVal(Ex, LCtx))); 728 break; 729 } 730 731 case UO_Imag: { 732 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 733 // FIXME: We don't have complex SValues yet. 734 if (Ex->getType()->isAnyComplexType()) { 735 // Just report "Unknown." 736 break; 737 } 738 // For all other types, UO_Imag returns 0. 739 ProgramStateRef state = Pred->getState(); 740 const LocationContext *LCtx = Pred->getLocationContext(); 741 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 742 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, X)); 743 break; 744 } 745 746 case UO_Plus: 747 assert(!U->isGLValue()); 748 // FALL-THROUGH. 749 case UO_Deref: 750 case UO_AddrOf: 751 case UO_Extension: { 752 // FIXME: We can probably just have some magic in Environment::getSVal() 753 // that propagates values, instead of creating a new node here. 754 // 755 // Unary "+" is a no-op, similar to a parentheses. We still have places 756 // where it may be a block-level expression, so we need to 757 // generate an extra node that just propagates the value of the 758 // subexpression. 759 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 760 ProgramStateRef state = Pred->getState(); 761 const LocationContext *LCtx = Pred->getLocationContext(); 762 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, 763 state->getSVal(Ex, LCtx))); 764 break; 765 } 766 767 case UO_LNot: 768 case UO_Minus: 769 case UO_Not: { 770 assert (!U->isGLValue()); 771 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 772 ProgramStateRef state = Pred->getState(); 773 const LocationContext *LCtx = Pred->getLocationContext(); 774 775 // Get the value of the subexpression. 776 SVal V = state->getSVal(Ex, LCtx); 777 778 if (V.isUnknownOrUndef()) { 779 Bldr.generateNode(U, Pred, state->BindExpr(U, LCtx, V)); 780 break; 781 } 782 783 switch (U->getOpcode()) { 784 default: 785 llvm_unreachable("Invalid Opcode."); 786 case UO_Not: 787 // FIXME: Do we need to handle promotions? 788 state = state->BindExpr(U, LCtx, evalComplement(cast<NonLoc>(V))); 789 break; 790 case UO_Minus: 791 // FIXME: Do we need to handle promotions? 792 state = state->BindExpr(U, LCtx, evalMinus(cast<NonLoc>(V))); 793 break; 794 case UO_LNot: 795 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 796 // 797 // Note: technically we do "E == 0", but this is the same in the 798 // transfer functions as "0 == E". 799 SVal Result; 800 if (isa<Loc>(V)) { 801 Loc X = svalBuilder.makeNull(); 802 Result = evalBinOp(state, BO_EQ, cast<Loc>(V), X, 803 U->getType()); 804 } 805 else { 806 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 807 Result = evalBinOp(state, BO_EQ, cast<NonLoc>(V), X, 808 U->getType()); 809 } 810 811 state = state->BindExpr(U, LCtx, Result); 812 break; 813 } 814 Bldr.generateNode(U, Pred, state); 815 break; 816 } 817 } 818 819} 820 821void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 822 ExplodedNode *Pred, 823 ExplodedNodeSet &Dst) { 824 // Handle ++ and -- (both pre- and post-increment). 825 assert (U->isIncrementDecrementOp()); 826 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 827 828 const LocationContext *LCtx = Pred->getLocationContext(); 829 ProgramStateRef state = Pred->getState(); 830 SVal loc = state->getSVal(Ex, LCtx); 831 832 // Perform a load. 833 ExplodedNodeSet Tmp; 834 evalLoad(Tmp, U, Ex, Pred, state, loc); 835 836 ExplodedNodeSet Dst2; 837 StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx); 838 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end();I!=E;++I) { 839 840 state = (*I)->getState(); 841 assert(LCtx == (*I)->getLocationContext()); 842 SVal V2_untested = state->getSVal(Ex, LCtx); 843 844 // Propagate unknown and undefined values. 845 if (V2_untested.isUnknownOrUndef()) { 846 Bldr.generateNode(U, *I, state->BindExpr(U, LCtx, V2_untested)); 847 continue; 848 } 849 DefinedSVal V2 = cast<DefinedSVal>(V2_untested); 850 851 // Handle all other values. 852 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub; 853 854 // If the UnaryOperator has non-location type, use its type to create the 855 // constant value. If the UnaryOperator has location type, create the 856 // constant with int type and pointer width. 857 SVal RHS; 858 859 if (U->getType()->isAnyPointerType()) 860 RHS = svalBuilder.makeArrayIndex(1); 861 else if (U->getType()->isIntegralOrEnumerationType()) 862 RHS = svalBuilder.makeIntVal(1, U->getType()); 863 else 864 RHS = UnknownVal(); 865 866 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 867 868 // Conjure a new symbol if necessary to recover precision. 869 if (Result.isUnknown()){ 870 DefinedOrUnknownSVal SymVal = 871 svalBuilder.conjureSymbolVal(0, Ex, LCtx, currBldrCtx->blockCount()); 872 Result = SymVal; 873 874 // If the value is a location, ++/-- should always preserve 875 // non-nullness. Check if the original value was non-null, and if so 876 // propagate that constraint. 877 if (Loc::isLocType(U->getType())) { 878 DefinedOrUnknownSVal Constraint = 879 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 880 881 if (!state->assume(Constraint, true)) { 882 // It isn't feasible for the original value to be null. 883 // Propagate this constraint. 884 Constraint = svalBuilder.evalEQ(state, SymVal, 885 svalBuilder.makeZeroVal(U->getType())); 886 887 888 state = state->assume(Constraint, false); 889 assert(state); 890 } 891 } 892 } 893 894 // Since the lvalue-to-rvalue conversion is explicit in the AST, 895 // we bind an l-value if the operator is prefix and an lvalue (in C++). 896 if (U->isGLValue()) 897 state = state->BindExpr(U, LCtx, loc); 898 else 899 state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result); 900 901 // Perform the store. 902 Bldr.takeNodes(*I); 903 ExplodedNodeSet Dst3; 904 evalStore(Dst3, U, U, *I, state, loc, Result); 905 Bldr.addNodes(Dst3); 906 } 907 Dst.insert(Dst2); 908} 909