ExprEngineC.cpp revision aa0aeb1cbe117db68d35700cb3a34aace0f99b99
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#include "clang/Analysis/Support/SaveAndRestore.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 const ProgramState *state = (*it)->getState(); 39 SVal LeftV = state->getSVal(LHS); 40 SVal RightV = state->getSVal(RHS); 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 !getConstraintManager().canReasonAbout(RightV)) { 49 unsigned Count = currentBuilderContext->getCurrentBlockCount(); 50 RightV = svalBuilder.getConjuredSymbolVal(NULL, B->getRHS(), 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->isLValue() ? LeftV : RightV; 55 evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, ExprVal), LeftV, RightV); 56 continue; 57 } 58 59 if (!B->isAssignmentOp()) { 60 StmtNodeBuilder Bldr(*it, Tmp2, *currentBuilderContext); 61 // Process non-assignments except commas or short-circuited 62 // logical expressions (LAnd and LOr). 63 SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType()); 64 if (Result.isUnknown()) { 65 Bldr.generateNode(B, *it, state); 66 continue; 67 } 68 69 state = state->BindExpr(B, Result); 70 Bldr.generateNode(B, *it, state); 71 continue; 72 } 73 74 assert (B->isCompoundAssignmentOp()); 75 76 switch (Op) { 77 default: 78 llvm_unreachable("Invalid opcode for compound assignment."); 79 case BO_MulAssign: Op = BO_Mul; break; 80 case BO_DivAssign: Op = BO_Div; break; 81 case BO_RemAssign: Op = BO_Rem; break; 82 case BO_AddAssign: Op = BO_Add; break; 83 case BO_SubAssign: Op = BO_Sub; break; 84 case BO_ShlAssign: Op = BO_Shl; break; 85 case BO_ShrAssign: Op = BO_Shr; break; 86 case BO_AndAssign: Op = BO_And; break; 87 case BO_XorAssign: Op = BO_Xor; break; 88 case BO_OrAssign: Op = BO_Or; break; 89 } 90 91 // Perform a load (the LHS). This performs the checks for 92 // null dereferences, and so on. 93 ExplodedNodeSet Tmp; 94 SVal location = LeftV; 95 evalLoad(Tmp, LHS, *it, state, location); 96 97 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; 98 ++I) { 99 100 state = (*I)->getState(); 101 SVal V = state->getSVal(LHS); 102 103 // Get the computation type. 104 QualType CTy = 105 cast<CompoundAssignOperator>(B)->getComputationResultType(); 106 CTy = getContext().getCanonicalType(CTy); 107 108 QualType CLHSTy = 109 cast<CompoundAssignOperator>(B)->getComputationLHSType(); 110 CLHSTy = getContext().getCanonicalType(CLHSTy); 111 112 QualType LTy = getContext().getCanonicalType(LHS->getType()); 113 114 // Promote LHS. 115 V = svalBuilder.evalCast(V, CLHSTy, LTy); 116 117 // Compute the result of the operation. 118 SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy), 119 B->getType(), CTy); 120 121 // EXPERIMENTAL: "Conjured" symbols. 122 // FIXME: Handle structs. 123 124 SVal LHSVal; 125 126 if (Result.isUnknown() || 127 !getConstraintManager().canReasonAbout(Result)) { 128 129 unsigned Count = currentBuilderContext->getCurrentBlockCount(); 130 131 // The symbolic value is actually for the type of the left-hand side 132 // expression, not the computation type, as this is the value the 133 // LValue on the LHS will bind to. 134 LHSVal = svalBuilder.getConjuredSymbolVal(NULL, B->getRHS(), LTy, 135 Count); 136 137 // However, we need to convert the symbol to the computation type. 138 Result = svalBuilder.evalCast(LHSVal, CTy, LTy); 139 } 140 else { 141 // The left-hand side may bind to a different value then the 142 // computation type. 143 LHSVal = svalBuilder.evalCast(Result, LTy, CTy); 144 } 145 146 // In C++, assignment and compound assignment operators return an 147 // lvalue. 148 if (B->isLValue()) 149 state = state->BindExpr(B, location); 150 else 151 state = state->BindExpr(B, Result); 152 153 evalStore(Tmp2, B, LHS, *I, state, location, LHSVal); 154 } 155 } 156 157 // FIXME: postvisits eventually go in ::Visit() 158 getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this); 159} 160 161void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred, 162 ExplodedNodeSet &Dst) { 163 164 CanQualType T = getContext().getCanonicalType(BE->getType()); 165 SVal V = svalBuilder.getBlockPointer(BE->getBlockDecl(), T, 166 Pred->getLocationContext()); 167 168 ExplodedNodeSet Tmp; 169 StmtNodeBuilder Bldr(Pred, Tmp, *currentBuilderContext); 170 Bldr.generateNode(BE, Pred, Pred->getState()->BindExpr(BE, V), false, 0, 171 ProgramPoint::PostLValueKind); 172 173 // FIXME: Move all post/pre visits to ::Visit(). 174 getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this); 175} 176 177void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, 178 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 179 180 ExplodedNodeSet dstPreStmt; 181 getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this); 182 183 if (CastE->getCastKind() == CK_LValueToRValue || 184 CastE->getCastKind() == CK_GetObjCProperty) { 185 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 186 I!=E; ++I) { 187 ExplodedNode *subExprNode = *I; 188 const ProgramState *state = subExprNode->getState(); 189 evalLoad(Dst, CastE, subExprNode, state, state->getSVal(Ex)); 190 } 191 return; 192 } 193 194 // All other casts. 195 QualType T = CastE->getType(); 196 QualType ExTy = Ex->getType(); 197 198 if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE)) 199 T = ExCast->getTypeAsWritten(); 200 201 StmtNodeBuilder Bldr(dstPreStmt, Dst, *currentBuilderContext); 202 for (ExplodedNodeSet::iterator I = dstPreStmt.begin(), E = dstPreStmt.end(); 203 I != E; ++I) { 204 205 Pred = *I; 206 207 switch (CastE->getCastKind()) { 208 case CK_LValueToRValue: 209 llvm_unreachable("LValueToRValue casts handled earlier."); 210 case CK_GetObjCProperty: 211 llvm_unreachable("GetObjCProperty casts handled earlier."); 212 case CK_ToVoid: 213 continue; 214 // The analyzer doesn't do anything special with these casts, 215 // since it understands retain/release semantics already. 216 case CK_ARCProduceObject: 217 case CK_ARCConsumeObject: 218 case CK_ARCReclaimReturnedObject: 219 case CK_ARCExtendBlockObject: // Fall-through. 220 // True no-ops. 221 case CK_NoOp: 222 case CK_FunctionToPointerDecay: { 223 // Copy the SVal of Ex to CastE. 224 const ProgramState *state = Pred->getState(); 225 SVal V = state->getSVal(Ex); 226 state = state->BindExpr(CastE, V); 227 Bldr.generateNode(CastE, Pred, state); 228 continue; 229 } 230 case CK_Dependent: 231 case CK_ArrayToPointerDecay: 232 case CK_BitCast: 233 case CK_LValueBitCast: 234 case CK_IntegralCast: 235 case CK_NullToPointer: 236 case CK_IntegralToPointer: 237 case CK_PointerToIntegral: 238 case CK_PointerToBoolean: 239 case CK_IntegralToBoolean: 240 case CK_IntegralToFloating: 241 case CK_FloatingToIntegral: 242 case CK_FloatingToBoolean: 243 case CK_FloatingCast: 244 case CK_FloatingRealToComplex: 245 case CK_FloatingComplexToReal: 246 case CK_FloatingComplexToBoolean: 247 case CK_FloatingComplexCast: 248 case CK_FloatingComplexToIntegralComplex: 249 case CK_IntegralRealToComplex: 250 case CK_IntegralComplexToReal: 251 case CK_IntegralComplexToBoolean: 252 case CK_IntegralComplexCast: 253 case CK_IntegralComplexToFloatingComplex: 254 case CK_CPointerToObjCPointerCast: 255 case CK_BlockPointerToObjCPointerCast: 256 case CK_AnyPointerToBlockPointerCast: 257 case CK_ObjCObjectLValueCast: { 258 // Delegate to SValBuilder to process. 259 const ProgramState *state = Pred->getState(); 260 SVal V = state->getSVal(Ex); 261 V = svalBuilder.evalCast(V, T, ExTy); 262 state = state->BindExpr(CastE, V); 263 Bldr.generateNode(CastE, Pred, state); 264 continue; 265 } 266 case CK_DerivedToBase: 267 case CK_UncheckedDerivedToBase: { 268 // For DerivedToBase cast, delegate to the store manager. 269 const ProgramState *state = Pred->getState(); 270 SVal val = state->getSVal(Ex); 271 val = getStoreManager().evalDerivedToBase(val, T); 272 state = state->BindExpr(CastE, val); 273 Bldr.generateNode(CastE, Pred, state); 274 continue; 275 } 276 // Various C++ casts that are not handled yet. 277 case CK_Dynamic: 278 case CK_ToUnion: 279 case CK_BaseToDerived: 280 case CK_NullToMemberPointer: 281 case CK_BaseToDerivedMemberPointer: 282 case CK_DerivedToBaseMemberPointer: 283 case CK_UserDefinedConversion: 284 case CK_ConstructorConversion: 285 case CK_VectorSplat: 286 case CK_MemberPointerToBoolean: { 287 // Recover some path-sensitivty by conjuring a new value. 288 QualType resultType = CastE->getType(); 289 if (CastE->isLValue()) 290 resultType = getContext().getPointerType(resultType); 291 292 SVal result = 293 svalBuilder.getConjuredSymbolVal(NULL, CastE, resultType, 294 currentBuilderContext->getCurrentBlockCount()); 295 296 const ProgramState *state = Pred->getState()->BindExpr(CastE, result); 297 Bldr.generateNode(CastE, Pred, state); 298 continue; 299 } 300 } 301 } 302} 303 304void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL, 305 ExplodedNode *Pred, 306 ExplodedNodeSet &Dst) { 307 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 308 309 const InitListExpr *ILE 310 = cast<InitListExpr>(CL->getInitializer()->IgnoreParens()); 311 312 const ProgramState *state = Pred->getState(); 313 SVal ILV = state->getSVal(ILE); 314 const LocationContext *LC = Pred->getLocationContext(); 315 state = state->bindCompoundLiteral(CL, LC, ILV); 316 317 if (CL->isLValue()) 318 B.generateNode(CL, Pred, state->BindExpr(CL, state->getLValue(CL, LC))); 319 else 320 B.generateNode(CL, Pred, state->BindExpr(CL, ILV)); 321} 322 323void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred, 324 ExplodedNodeSet &Dst) { 325 326 // FIXME: static variables may have an initializer, but the second 327 // time a function is called those values may not be current. 328 // This may need to be reflected in the CFG. 329 330 // Assumption: The CFG has one DeclStmt per Decl. 331 const Decl *D = *DS->decl_begin(); 332 333 if (!D || !isa<VarDecl>(D)) { 334 //TODO:AZ: remove explicit insertion after refactoring is done. 335 Dst.insert(Pred); 336 return; 337 } 338 339 // FIXME: all pre/post visits should eventually be handled by ::Visit(). 340 ExplodedNodeSet dstPreVisit; 341 getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this); 342 343 StmtNodeBuilder B(dstPreVisit, Dst, *currentBuilderContext); 344 const VarDecl *VD = dyn_cast<VarDecl>(D); 345 for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end(); 346 I!=E; ++I) { 347 ExplodedNode *N = *I; 348 const ProgramState *state = N->getState(); 349 350 // Decls without InitExpr are not initialized explicitly. 351 const LocationContext *LC = N->getLocationContext(); 352 353 if (const Expr *InitEx = VD->getInit()) { 354 SVal InitVal = state->getSVal(InitEx); 355 356 // We bound the temp obj region to the CXXConstructExpr. Now recover 357 // the lazy compound value when the variable is not a reference. 358 if (AMgr.getLangOptions().CPlusPlus && VD->getType()->isRecordType() && 359 !VD->getType()->isReferenceType() && isa<loc::MemRegionVal>(InitVal)){ 360 InitVal = state->getSVal(cast<loc::MemRegionVal>(InitVal).getRegion()); 361 assert(isa<nonloc::LazyCompoundVal>(InitVal)); 362 } 363 364 // Recover some path-sensitivity if a scalar value evaluated to 365 // UnknownVal. 366 if ((InitVal.isUnknown() || 367 !getConstraintManager().canReasonAbout(InitVal)) && 368 !VD->getType()->isReferenceType()) { 369 InitVal = svalBuilder.getConjuredSymbolVal(NULL, InitEx, 370 currentBuilderContext->getCurrentBlockCount()); 371 } 372 B.takeNodes(N); 373 evalBind(Dst, DS, N, state->getLValue(VD, LC), InitVal, true); 374 B.addNodes(Dst); 375 } 376 else { 377 B.generateNode(DS, N,state->bindDeclWithNoInit(state->getRegion(VD, LC))); 378 } 379 } 380} 381 382void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred, 383 ExplodedNodeSet &Dst) { 384 assert(B->getOpcode() == BO_LAnd || 385 B->getOpcode() == BO_LOr); 386 387 StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); 388 const ProgramState *state = Pred->getState(); 389 SVal X = state->getSVal(B); 390 assert(X.isUndef()); 391 392 const Expr *Ex = (const Expr*) cast<UndefinedVal>(X).getData(); 393 assert(Ex); 394 395 if (Ex == B->getRHS()) { 396 X = state->getSVal(Ex); 397 398 // Handle undefined values. 399 if (X.isUndef()) { 400 Bldr.generateNode(B, Pred, state->BindExpr(B, X)); 401 return; 402 } 403 404 DefinedOrUnknownSVal XD = cast<DefinedOrUnknownSVal>(X); 405 406 // We took the RHS. Because the value of the '&&' or '||' expression must 407 // evaluate to 0 or 1, we must assume the value of the RHS evaluates to 0 408 // or 1. Alternatively, we could take a lazy approach, and calculate this 409 // value later when necessary. We don't have the machinery in place for 410 // this right now, and since most logical expressions are used for branches, 411 // the payoff is not likely to be large. Instead, we do eager evaluation. 412 if (const ProgramState *newState = state->assume(XD, true)) 413 Bldr.generateNode(B, Pred, 414 newState->BindExpr(B, svalBuilder.makeIntVal(1U, B->getType()))); 415 416 if (const ProgramState *newState = state->assume(XD, false)) 417 Bldr.generateNode(B, Pred, 418 newState->BindExpr(B, svalBuilder.makeIntVal(0U, B->getType()))); 419 } 420 else { 421 // We took the LHS expression. Depending on whether we are '&&' or 422 // '||' we know what the value of the expression is via properties of 423 // the short-circuiting. 424 X = svalBuilder.makeIntVal(B->getOpcode() == BO_LAnd ? 0U : 1U, 425 B->getType()); 426 Bldr.generateNode(B, Pred, state->BindExpr(B, X)); 427 } 428} 429 430void ExprEngine::VisitInitListExpr(const InitListExpr *IE, 431 ExplodedNode *Pred, 432 ExplodedNodeSet &Dst) { 433 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 434 435 const ProgramState *state = Pred->getState(); 436 QualType T = getContext().getCanonicalType(IE->getType()); 437 unsigned NumInitElements = IE->getNumInits(); 438 439 if (T->isArrayType() || T->isRecordType() || T->isVectorType()) { 440 llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList(); 441 442 // Handle base case where the initializer has no elements. 443 // e.g: static int* myArray[] = {}; 444 if (NumInitElements == 0) { 445 SVal V = svalBuilder.makeCompoundVal(T, vals); 446 B.generateNode(IE, Pred, state->BindExpr(IE, V)); 447 return; 448 } 449 450 for (InitListExpr::const_reverse_iterator it = IE->rbegin(), 451 ei = IE->rend(); it != ei; ++it) { 452 vals = getBasicVals().consVals(state->getSVal(cast<Expr>(*it)), vals); 453 } 454 455 B.generateNode(IE, Pred, 456 state->BindExpr(IE, svalBuilder.makeCompoundVal(T, vals))); 457 return; 458 } 459 460 if (Loc::isLocType(T) || T->isIntegerType()) { 461 assert(IE->getNumInits() == 1); 462 const Expr *initEx = IE->getInit(0); 463 B.generateNode(IE, Pred, state->BindExpr(IE, state->getSVal(initEx))); 464 return; 465 } 466 467 llvm_unreachable("unprocessed InitListExpr type"); 468} 469 470void ExprEngine::VisitGuardedExpr(const Expr *Ex, 471 const Expr *L, 472 const Expr *R, 473 ExplodedNode *Pred, 474 ExplodedNodeSet &Dst) { 475 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 476 477 const ProgramState *state = Pred->getState(); 478 SVal X = state->getSVal(Ex); 479 assert (X.isUndef()); 480 const Expr *SE = (Expr*) cast<UndefinedVal>(X).getData(); 481 assert(SE); 482 X = state->getSVal(SE); 483 484 // Make sure that we invalidate the previous binding. 485 B.generateNode(Ex, Pred, state->BindExpr(Ex, X, true)); 486} 487 488void ExprEngine:: 489VisitOffsetOfExpr(const OffsetOfExpr *OOE, 490 ExplodedNode *Pred, ExplodedNodeSet &Dst) { 491 StmtNodeBuilder B(Pred, Dst, *currentBuilderContext); 492 Expr::EvalResult Res; 493 if (OOE->Evaluate(Res, getContext()) && Res.Val.isInt()) { 494 const APSInt &IV = Res.Val.getInt(); 495 assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType())); 496 assert(OOE->getType()->isIntegerType()); 497 assert(IV.isSigned() == OOE->getType()->isSignedIntegerOrEnumerationType()); 498 SVal X = svalBuilder.makeIntVal(IV); 499 B.generateNode(OOE, Pred, Pred->getState()->BindExpr(OOE, X)); 500 } 501 // FIXME: Handle the case where __builtin_offsetof is not a constant. 502} 503 504 505void ExprEngine:: 506VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex, 507 ExplodedNode *Pred, 508 ExplodedNodeSet &Dst) { 509 StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); 510 511 QualType T = Ex->getTypeOfArgument(); 512 513 if (Ex->getKind() == UETT_SizeOf) { 514 if (!T->isIncompleteType() && !T->isConstantSizeType()) { 515 assert(T->isVariableArrayType() && "Unknown non-constant-sized type."); 516 517 // FIXME: Add support for VLA type arguments and VLA expressions. 518 // When that happens, we should probably refactor VLASizeChecker's code. 519 return; 520 } 521 else if (T->getAs<ObjCObjectType>()) { 522 // Some code tries to take the sizeof an ObjCObjectType, relying that 523 // the compiler has laid out its representation. Just report Unknown 524 // for these. 525 return; 526 } 527 } 528 529 Expr::EvalResult Result; 530 Ex->Evaluate(Result, getContext()); 531 CharUnits amt = CharUnits::fromQuantity(Result.Val.getInt().getZExtValue()); 532 533 const ProgramState *state = Pred->getState(); 534 state = state->BindExpr(Ex, svalBuilder.makeIntVal(amt.getQuantity(), 535 Ex->getType())); 536 Bldr.generateNode(Ex, Pred, state); 537} 538 539void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, 540 ExplodedNode *Pred, 541 ExplodedNodeSet &Dst) { 542 StmtNodeBuilder Bldr(Pred, Dst, *currentBuilderContext); 543 bool IncDec = false; 544 switch (U->getOpcode()) { 545 default: { 546 Bldr.takeNodes(Pred); 547 IncDec = true; 548 ExplodedNodeSet Tmp; 549 VisitIncrementDecrementOperator(U, Pred, Tmp); 550 Bldr.addNodes(Tmp); 551 } 552 break; 553 case UO_Real: { 554 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 555 ExplodedNodeSet Tmp; 556 Visit(Ex, Pred, Tmp); 557 558 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) { 559 560 // FIXME: We don't have complex SValues yet. 561 if (Ex->getType()->isAnyComplexType()) { 562 // Just report "Unknown." 563 continue; 564 } 565 566 // For all other types, UO_Real is an identity operation. 567 assert (U->getType() == Ex->getType()); 568 const ProgramState *state = (*I)->getState(); 569 Bldr.generateNode(U, *I, state->BindExpr(U, state->getSVal(Ex))); 570 } 571 572 break; 573 } 574 575 case UO_Imag: { 576 577 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 578 ExplodedNodeSet Tmp; 579 Visit(Ex, Pred, Tmp); 580 581 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) { 582 // FIXME: We don't have complex SValues yet. 583 if (Ex->getType()->isAnyComplexType()) { 584 // Just report "Unknown." 585 continue; 586 } 587 588 // For all other types, UO_Imag returns 0. 589 const ProgramState *state = (*I)->getState(); 590 SVal X = svalBuilder.makeZeroVal(Ex->getType()); 591 Bldr.generateNode(U, *I, state->BindExpr(U, X)); 592 } 593 594 break; 595 } 596 597 case UO_Plus: 598 assert(!U->isLValue()); 599 // FALL-THROUGH. 600 case UO_Deref: 601 case UO_AddrOf: 602 case UO_Extension: { 603 604 // Unary "+" is a no-op, similar to a parentheses. We still have places 605 // where it may be a block-level expression, so we need to 606 // generate an extra node that just propagates the value of the 607 // subexpression. 608 609 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 610 ExplodedNodeSet Tmp; 611 Visit(Ex, Pred, Tmp); 612 613 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) { 614 const ProgramState *state = (*I)->getState(); 615 Bldr.generateNode(U, *I, state->BindExpr(U, state->getSVal(Ex))); 616 } 617 618 break; 619 } 620 621 case UO_LNot: 622 case UO_Minus: 623 case UO_Not: { 624 assert (!U->isLValue()); 625 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 626 ExplodedNodeSet Tmp; 627 Visit(Ex, Pred, Tmp); 628 629 for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) { 630 const ProgramState *state = (*I)->getState(); 631 632 // Get the value of the subexpression. 633 SVal V = state->getSVal(Ex); 634 635 if (V.isUnknownOrUndef()) { 636 Bldr.generateNode(U, *I, state->BindExpr(U, V)); 637 continue; 638 } 639 640 switch (U->getOpcode()) { 641 default: 642 llvm_unreachable("Invalid Opcode."); 643 644 case UO_Not: 645 // FIXME: Do we need to handle promotions? 646 state = state->BindExpr(U, evalComplement(cast<NonLoc>(V))); 647 break; 648 649 case UO_Minus: 650 // FIXME: Do we need to handle promotions? 651 state = state->BindExpr(U, evalMinus(cast<NonLoc>(V))); 652 break; 653 654 case UO_LNot: 655 656 // C99 6.5.3.3: "The expression !E is equivalent to (0==E)." 657 // 658 // Note: technically we do "E == 0", but this is the same in the 659 // transfer functions as "0 == E". 660 SVal Result; 661 662 if (isa<Loc>(V)) { 663 Loc X = svalBuilder.makeNull(); 664 Result = evalBinOp(state, BO_EQ, cast<Loc>(V), X, 665 U->getType()); 666 } 667 else { 668 nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType())); 669 Result = evalBinOp(state, BO_EQ, cast<NonLoc>(V), X, 670 U->getType()); 671 } 672 673 state = state->BindExpr(U, Result); 674 675 break; 676 } 677 Bldr.generateNode(U, *I, state); 678 } 679 break; 680 } 681 } 682 683} 684 685void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U, 686 ExplodedNode *Pred, 687 ExplodedNodeSet &Dst) { 688 // Handle ++ and -- (both pre- and post-increment). 689 assert (U->isIncrementDecrementOp()); 690 ExplodedNodeSet Tmp; 691 const Expr *Ex = U->getSubExpr()->IgnoreParens(); 692 Visit(Ex, Pred, Tmp); 693 694 for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I!=E; ++I) { 695 696 const ProgramState *state = (*I)->getState(); 697 SVal loc = state->getSVal(Ex); 698 699 // Perform a load. 700 ExplodedNodeSet Tmp2; 701 evalLoad(Tmp2, Ex, *I, state, loc); 702 703 ExplodedNodeSet Dst2; 704 StmtNodeBuilder Bldr(Tmp2, Dst2, *currentBuilderContext); 705 for (ExplodedNodeSet::iterator I2=Tmp2.begin(), E2=Tmp2.end();I2!=E2;++I2) { 706 707 state = (*I2)->getState(); 708 SVal V2_untested = state->getSVal(Ex); 709 710 // Propagate unknown and undefined values. 711 if (V2_untested.isUnknownOrUndef()) { 712 Bldr.generateNode(U, *I2, state->BindExpr(U, V2_untested)); 713 continue; 714 } 715 DefinedSVal V2 = cast<DefinedSVal>(V2_untested); 716 717 // Handle all other values. 718 BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add 719 : BO_Sub; 720 721 // If the UnaryOperator has non-location type, use its type to create the 722 // constant value. If the UnaryOperator has location type, create the 723 // constant with int type and pointer width. 724 SVal RHS; 725 726 if (U->getType()->isAnyPointerType()) 727 RHS = svalBuilder.makeArrayIndex(1); 728 else 729 RHS = svalBuilder.makeIntVal(1, U->getType()); 730 731 SVal Result = evalBinOp(state, Op, V2, RHS, U->getType()); 732 733 // Conjure a new symbol if necessary to recover precision. 734 if (Result.isUnknown() || !getConstraintManager().canReasonAbout(Result)){ 735 DefinedOrUnknownSVal SymVal = 736 svalBuilder.getConjuredSymbolVal(NULL, Ex, 737 currentBuilderContext->getCurrentBlockCount()); 738 Result = SymVal; 739 740 // If the value is a location, ++/-- should always preserve 741 // non-nullness. Check if the original value was non-null, and if so 742 // propagate that constraint. 743 if (Loc::isLocType(U->getType())) { 744 DefinedOrUnknownSVal Constraint = 745 svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType())); 746 747 if (!state->assume(Constraint, true)) { 748 // It isn't feasible for the original value to be null. 749 // Propagate this constraint. 750 Constraint = svalBuilder.evalEQ(state, SymVal, 751 svalBuilder.makeZeroVal(U->getType())); 752 753 754 state = state->assume(Constraint, false); 755 assert(state); 756 } 757 } 758 } 759 760 // Since the lvalue-to-rvalue conversion is explicit in the AST, 761 // we bind an l-value if the operator is prefix and an lvalue (in C++). 762 if (U->isLValue()) 763 state = state->BindExpr(U, loc); 764 else 765 state = state->BindExpr(U, U->isPostfix() ? V2 : Result); 766 767 // Perform the store. 768 Bldr.takeNodes(*I2); 769 ExplodedNodeSet Dst4; 770 evalStore(Dst4, NULL, U, *I2, state, loc, Result); 771 Bldr.addNodes(Dst4); 772 } 773 Dst.insert(Dst2); 774 } 775} 776