clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp

   1 //=-- ExprEngineC.cpp - ExprEngine support for C expressions ----*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 //  This file defines ExprEngine's support for C expressions.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/AST/DeclCXX.h"
  14 #include "clang/AST/ExprCXX.h"
  15 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
  16 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
  17 #include <optional>
  18
  19 using namespace clang;
  20 using namespace ento;
  21 using llvm::APSInt;
  22
  23 /// Optionally conjure and return a symbol for offset when processing
  24 /// an expression \p Expression.
  25 /// If \p Other is a location, conjure a symbol for \p Symbol
  26 /// (offset) if it is unknown so that memory arithmetic always
  27 /// results in an ElementRegion.
  28 /// \p Count The number of times the current basic block was visited.
  29 static SVal conjureOffsetSymbolOnLocation(
  30     SVal Symbol, SVal Other, Expr* Expression, SValBuilder &svalBuilder,
  31     unsigned Count, const LocationContext *LCtx) {
  32   QualType Ty = Expression->getType();
  33   if (isa<Loc>(Other) && Ty->isIntegralOrEnumerationType() &&
  34       Symbol.isUnknown()) {
  35     return svalBuilder.conjureSymbolVal(Expression, LCtx, Ty, Count);
  36   }
  37   return Symbol;
  38 }
  39
  40 void ExprEngine::VisitBinaryOperator(const BinaryOperator* B,
  41                                      ExplodedNode *Pred,
  42                                      ExplodedNodeSet &Dst) {
  43
  44   Expr *LHS = B->getLHS()->IgnoreParens();
  45   Expr *RHS = B->getRHS()->IgnoreParens();
  46
  47   // FIXME: Prechecks eventually go in ::Visit().
  48   ExplodedNodeSet CheckedSet;
  49   ExplodedNodeSet Tmp2;
  50   getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, B, *this);
  51
  52   // With both the LHS and RHS evaluated, process the operation itself.
  53   for (ExplodedNodeSet::iterator it=CheckedSet.begin(), ei=CheckedSet.end();
  54          it != ei; ++it) {
  55
  56     ProgramStateRef state = (*it)->getState();
  57     const LocationContext *LCtx = (*it)->getLocationContext();
  58     SVal LeftV = state->getSVal(LHS, LCtx);
  59     SVal RightV = state->getSVal(RHS, LCtx);
  60
  61     BinaryOperator::Opcode Op = B->getOpcode();
  62
  63     if (Op == BO_Assign) {
  64       // EXPERIMENTAL: "Conjured" symbols.
  65       // FIXME: Handle structs.
  66       if (RightV.isUnknown()) {
  67         unsigned Count = currBldrCtx->blockCount();
  68         RightV = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx,
  69                                               Count);
  70       }
  71       // Simulate the effects of a "store":  bind the value of the RHS
  72       // to the L-Value represented by the LHS.
  73       SVal ExprVal = B->isGLValue() ? LeftV : RightV;
  74       evalStore(Tmp2, B, LHS, *it, state->BindExpr(B, LCtx, ExprVal),
  75                 LeftV, RightV);
  76       continue;
  77     }
  78
  79     if (!B->isAssignmentOp()) {
  80       StmtNodeBuilder Bldr(*it, Tmp2, *currBldrCtx);
  81
  82       if (B->isAdditiveOp()) {
  83         // TODO: This can be removed after we enable history tracking with
  84         // SymSymExpr.
  85         unsigned Count = currBldrCtx->blockCount();
  86         RightV = conjureOffsetSymbolOnLocation(
  87             RightV, LeftV, RHS, svalBuilder, Count, LCtx);
  88         LeftV = conjureOffsetSymbolOnLocation(
  89             LeftV, RightV, LHS, svalBuilder, Count, LCtx);
  90       }
  91
  92       // Although we don't yet model pointers-to-members, we do need to make
  93       // sure that the members of temporaries have a valid 'this' pointer for
  94       // other checks.
  95       if (B->getOpcode() == BO_PtrMemD)
  96         state = createTemporaryRegionIfNeeded(state, LCtx, LHS);
  97
  98       // Process non-assignments except commas or short-circuited
  99       // logical expressions (LAnd and LOr).
 100       SVal Result = evalBinOp(state, Op, LeftV, RightV, B->getType());
 101       if (!Result.isUnknown()) {
 102         state = state->BindExpr(B, LCtx, Result);
 103       } else {
 104         // If we cannot evaluate the operation escape the operands.
 105         state = escapeValues(state, LeftV, PSK_EscapeOther);
 106         state = escapeValues(state, RightV, PSK_EscapeOther);
 107       }
 108
 109       Bldr.generateNode(B, *it, state);
 110       continue;
 111     }
 112
 113     assert (B->isCompoundAssignmentOp());
 114
 115     switch (Op) {
 116       default:
 117         llvm_unreachable("Invalid opcode for compound assignment.");
 118       case BO_MulAssign: Op = BO_Mul; break;
 119       case BO_DivAssign: Op = BO_Div; break;
 120       case BO_RemAssign: Op = BO_Rem; break;
 121       case BO_AddAssign: Op = BO_Add; break;
 122       case BO_SubAssign: Op = BO_Sub; break;
 123       case BO_ShlAssign: Op = BO_Shl; break;
 124       case BO_ShrAssign: Op = BO_Shr; break;
 125       case BO_AndAssign: Op = BO_And; break;
 126       case BO_XorAssign: Op = BO_Xor; break;
 127       case BO_OrAssign:  Op = BO_Or;  break;
 128     }
 129
 130     // Perform a load (the LHS).  This performs the checks for
 131     // null dereferences, and so on.
 132     ExplodedNodeSet Tmp;
 133     SVal location = LeftV;
 134     evalLoad(Tmp, B, LHS, *it, state, location);
 135
 136     for (ExplodedNode *N : Tmp) {
 137       state = N->getState();
 138       const LocationContext *LCtx = N->getLocationContext();
 139       SVal V = state->getSVal(LHS, LCtx);
 140
 141       // Get the computation type.
 142       QualType CTy =
 143         cast<CompoundAssignOperator>(B)->getComputationResultType();
 144       CTy = getContext().getCanonicalType(CTy);
 145
 146       QualType CLHSTy =
 147         cast<CompoundAssignOperator>(B)->getComputationLHSType();
 148       CLHSTy = getContext().getCanonicalType(CLHSTy);
 149
 150       QualType LTy = getContext().getCanonicalType(LHS->getType());
 151
 152       // Promote LHS.
 153       V = svalBuilder.evalCast(V, CLHSTy, LTy);
 154
 155       // Compute the result of the operation.
 156       SVal Result = svalBuilder.evalCast(evalBinOp(state, Op, V, RightV, CTy),
 157                                          B->getType(), CTy);
 158
 159       // EXPERIMENTAL: "Conjured" symbols.
 160       // FIXME: Handle structs.
 161
 162       SVal LHSVal;
 163
 164       if (Result.isUnknown()) {
 165         // The symbolic value is actually for the type of the left-hand side
 166         // expression, not the computation type, as this is the value the
 167         // LValue on the LHS will bind to.
 168         LHSVal = svalBuilder.conjureSymbolVal(nullptr, B->getRHS(), LCtx, LTy,
 169                                               currBldrCtx->blockCount());
 170         // However, we need to convert the symbol to the computation type.
 171         Result = svalBuilder.evalCast(LHSVal, CTy, LTy);
 172       } else {
 173         // The left-hand side may bind to a different value then the
 174         // computation type.
 175         LHSVal = svalBuilder.evalCast(Result, LTy, CTy);
 176       }
 177
 178       // In C++, assignment and compound assignment operators return an
 179       // lvalue.
 180       if (B->isGLValue())
 181         state = state->BindExpr(B, LCtx, location);
 182       else
 183         state = state->BindExpr(B, LCtx, Result);
 184
 185       evalStore(Tmp2, B, LHS, N, state, location, LHSVal);
 186     }
 187   }
 188
 189   // FIXME: postvisits eventually go in ::Visit()
 190   getCheckerManager().runCheckersForPostStmt(Dst, Tmp2, B, *this);
 191 }
 192
 193 void ExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred,
 194                                 ExplodedNodeSet &Dst) {
 195
 196   CanQualType T = getContext().getCanonicalType(BE->getType());
 197
 198   const BlockDecl *BD = BE->getBlockDecl();
 199   // Get the value of the block itself.
 200   SVal V = svalBuilder.getBlockPointer(BD, T,
 201                                        Pred->getLocationContext(),
 202                                        currBldrCtx->blockCount());
 203
 204   ProgramStateRef State = Pred->getState();
 205
 206   // If we created a new MemRegion for the block, we should explicitly bind
 207   // the captured variables.
 208   if (const BlockDataRegion *BDR =
 209       dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) {
 210
 211     auto ReferencedVars = BDR->referenced_vars();
 212     auto CI = BD->capture_begin();
 213     auto CE = BD->capture_end();
 214     for (auto Var : ReferencedVars) {
 215       const VarRegion *capturedR = Var.getCapturedRegion();
 216       const TypedValueRegion *originalR = Var.getOriginalRegion();
 217
 218       // If the capture had a copy expression, use the result of evaluating
 219       // that expression, otherwise use the original value.
 220       // We rely on the invariant that the block declaration's capture variables
 221       // are a prefix of the BlockDataRegion's referenced vars (which may include
 222       // referenced globals, etc.) to enable fast lookup of the capture for a
 223       // given referenced var.
 224       const Expr *copyExpr = nullptr;
 225       if (CI != CE) {
 226         assert(CI->getVariable() == capturedR->getDecl());
 227         copyExpr = CI->getCopyExpr();
 228         CI++;
 229       }
 230
 231       if (capturedR != originalR) {
 232         SVal originalV;
 233         const LocationContext *LCtx = Pred->getLocationContext();
 234         if (copyExpr) {
 235           originalV = State->getSVal(copyExpr, LCtx);
 236         } else {
 237           originalV = State->getSVal(loc::MemRegionVal(originalR));
 238         }
 239         State = State->bindLoc(loc::MemRegionVal(capturedR), originalV, LCtx);
 240       }
 241     }
 242   }
 243
 244   ExplodedNodeSet Tmp;
 245   StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
 246   Bldr.generateNode(BE, Pred,
 247                     State->BindExpr(BE, Pred->getLocationContext(), V),
 248                     nullptr, ProgramPoint::PostLValueKind);
 249
 250   // FIXME: Move all post/pre visits to ::Visit().
 251   getCheckerManager().runCheckersForPostStmt(Dst, Tmp, BE, *this);
 252 }
 253
 254 ProgramStateRef ExprEngine::handleLValueBitCast(
 255     ProgramStateRef state, const Expr* Ex, const LocationContext* LCtx,
 256     QualType T, QualType ExTy, const CastExpr* CastE, StmtNodeBuilder& Bldr,
 257     ExplodedNode* Pred) {
 258   if (T->isLValueReferenceType()) {
 259     assert(!CastE->getType()->isLValueReferenceType());
 260     ExTy = getContext().getLValueReferenceType(ExTy);
 261   } else if (T->isRValueReferenceType()) {
 262     assert(!CastE->getType()->isRValueReferenceType());
 263     ExTy = getContext().getRValueReferenceType(ExTy);
 264   }
 265   // Delegate to SValBuilder to process.
 266   SVal OrigV = state->getSVal(Ex, LCtx);
 267   SVal SimplifiedOrigV = svalBuilder.simplifySVal(state, OrigV);
 268   SVal V = svalBuilder.evalCast(SimplifiedOrigV, T, ExTy);
 269   // Negate the result if we're treating the boolean as a signed i1
 270   if (CastE->getCastKind() == CK_BooleanToSignedIntegral && V.isValid())
 271     V = svalBuilder.evalMinus(V.castAs<NonLoc>());
 272
 273   state = state->BindExpr(CastE, LCtx, V);
 274   if (V.isUnknown() && !OrigV.isUnknown()) {
 275     state = escapeValues(state, OrigV, PSK_EscapeOther);
 276   }
 277   Bldr.generateNode(CastE, Pred, state);
 278
 279   return state;
 280 }
 281
 282 void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
 283                            ExplodedNode *Pred, ExplodedNodeSet &Dst) {
 284
 285   ExplodedNodeSet dstPreStmt;
 286   getCheckerManager().runCheckersForPreStmt(dstPreStmt, Pred, CastE, *this);
 287
 288   if (CastE->getCastKind() == CK_LValueToRValue ||
 289       CastE->getCastKind() == CK_LValueToRValueBitCast) {
 290     for (ExplodedNode *subExprNode : dstPreStmt) {
 291       ProgramStateRef state = subExprNode->getState();
 292       const LocationContext *LCtx = subExprNode->getLocationContext();
 293       evalLoad(Dst, CastE, CastE, subExprNode, state, state->getSVal(Ex, LCtx));
 294     }
 295     return;
 296   }
 297
 298   // All other casts.
 299   QualType T = CastE->getType();
 300   QualType ExTy = Ex->getType();
 301
 302   if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE))
 303     T = ExCast->getTypeAsWritten();
 304
 305   StmtNodeBuilder Bldr(dstPreStmt, Dst, *currBldrCtx);
 306   for (ExplodedNode *Pred : dstPreStmt) {
 307     ProgramStateRef state = Pred->getState();
 308     const LocationContext *LCtx = Pred->getLocationContext();
 309
 310     switch (CastE->getCastKind()) {
 311       case CK_LValueToRValue:
 312       case CK_LValueToRValueBitCast:
 313         llvm_unreachable("LValueToRValue casts handled earlier.");
 314       case CK_ToVoid:
 315         continue;
 316         // The analyzer doesn't do anything special with these casts,
 317         // since it understands retain/release semantics already.
 318       case CK_ARCProduceObject:
 319       case CK_ARCConsumeObject:
 320       case CK_ARCReclaimReturnedObject:
 321       case CK_ARCExtendBlockObject: // Fall-through.
 322       case CK_CopyAndAutoreleaseBlockObject:
 323         // The analyser can ignore atomic casts for now, although some future
 324         // checkers may want to make certain that you're not modifying the same
 325         // value through atomic and nonatomic pointers.
 326       case CK_AtomicToNonAtomic:
 327       case CK_NonAtomicToAtomic:
 328         // True no-ops.
 329       case CK_NoOp:
 330       case CK_ConstructorConversion:
 331       case CK_UserDefinedConversion:
 332       case CK_FunctionToPointerDecay:
 333       case CK_BuiltinFnToFnPtr:
 334       case CK_HLSLArrayRValue: {
 335         // Copy the SVal of Ex to CastE.
 336         ProgramStateRef state = Pred->getState();
 337         const LocationContext *LCtx = Pred->getLocationContext();
 338         SVal V = state->getSVal(Ex, LCtx);
 339         state = state->BindExpr(CastE, LCtx, V);
 340         Bldr.generateNode(CastE, Pred, state);
 341         continue;
 342       }
 343       case CK_MemberPointerToBoolean:
 344       case CK_PointerToBoolean: {
 345         SVal V = state->getSVal(Ex, LCtx);
 346         auto PTMSV = V.getAs<nonloc::PointerToMember>();
 347         if (PTMSV)
 348           V = svalBuilder.makeTruthVal(!PTMSV->isNullMemberPointer(), ExTy);
 349         if (V.isUndef() || PTMSV) {
 350           state = state->BindExpr(CastE, LCtx, V);
 351           Bldr.generateNode(CastE, Pred, state);
 352           continue;
 353         }
 354         // Explicitly proceed with default handler for this case cascade.
 355         state =
 356             handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
 357         continue;
 358       }
 359       case CK_Dependent:
 360       case CK_ArrayToPointerDecay:
 361       case CK_BitCast:
 362       case CK_AddressSpaceConversion:
 363       case CK_BooleanToSignedIntegral:
 364       case CK_IntegralToPointer:
 365       case CK_PointerToIntegral: {
 366         SVal V = state->getSVal(Ex, LCtx);
 367         if (isa<nonloc::PointerToMember>(V)) {
 368           state = state->BindExpr(CastE, LCtx, UnknownVal());
 369           Bldr.generateNode(CastE, Pred, state);
 370           continue;
 371         }
 372         // Explicitly proceed with default handler for this case cascade.
 373         state =
 374             handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
 375         continue;
 376       }
 377       case CK_IntegralToBoolean:
 378       case CK_IntegralToFloating:
 379       case CK_FloatingToIntegral:
 380       case CK_FloatingToBoolean:
 381       case CK_FloatingCast:
 382       case CK_FloatingRealToComplex:
 383       case CK_FloatingComplexToReal:
 384       case CK_FloatingComplexToBoolean:
 385       case CK_FloatingComplexCast:
 386       case CK_FloatingComplexToIntegralComplex:
 387       case CK_IntegralRealToComplex:
 388       case CK_IntegralComplexToReal:
 389       case CK_IntegralComplexToBoolean:
 390       case CK_IntegralComplexCast:
 391       case CK_IntegralComplexToFloatingComplex:
 392       case CK_CPointerToObjCPointerCast:
 393       case CK_BlockPointerToObjCPointerCast:
 394       case CK_AnyPointerToBlockPointerCast:
 395       case CK_ObjCObjectLValueCast:
 396       case CK_ZeroToOCLOpaqueType:
 397       case CK_IntToOCLSampler:
 398       case CK_LValueBitCast:
 399       case CK_FloatingToFixedPoint:
 400       case CK_FixedPointToFloating:
 401       case CK_FixedPointCast:
 402       case CK_FixedPointToBoolean:
 403       case CK_FixedPointToIntegral:
 404       case CK_IntegralToFixedPoint: {
 405         state =
 406             handleLValueBitCast(state, Ex, LCtx, T, ExTy, CastE, Bldr, Pred);
 407         continue;
 408       }
 409       case CK_IntegralCast: {
 410         // Delegate to SValBuilder to process.
 411         SVal V = state->getSVal(Ex, LCtx);
 412         if (AMgr.options.ShouldSupportSymbolicIntegerCasts)
 413           V = svalBuilder.evalCast(V, T, ExTy);
 414         else
 415           V = svalBuilder.evalIntegralCast(state, V, T, ExTy);
 416         state = state->BindExpr(CastE, LCtx, V);
 417         Bldr.generateNode(CastE, Pred, state);
 418         continue;
 419       }
 420       case CK_DerivedToBase:
 421       case CK_UncheckedDerivedToBase: {
 422         // For DerivedToBase cast, delegate to the store manager.
 423         SVal val = state->getSVal(Ex, LCtx);
 424         val = getStoreManager().evalDerivedToBase(val, CastE);
 425         state = state->BindExpr(CastE, LCtx, val);
 426         Bldr.generateNode(CastE, Pred, state);
 427         continue;
 428       }
 429       // Handle C++ dyn_cast.
 430       case CK_Dynamic: {
 431         SVal val = state->getSVal(Ex, LCtx);
 432
 433         // Compute the type of the result.
 434         QualType resultType = CastE->getType();
 435         if (CastE->isGLValue())
 436           resultType = getContext().getPointerType(resultType);
 437
 438         bool Failed = true;
 439
 440         // Check if the value being cast does not evaluates to 0.
 441         if (!val.isZeroConstant())
 442           if (std::optional<SVal> V =
 443                   StateMgr.getStoreManager().evalBaseToDerived(val, T)) {
 444           val = *V;
 445           Failed = false;
 446           }
 447
 448         if (Failed) {
 449           if (T->isReferenceType()) {
 450             // A bad_cast exception is thrown if input value is a reference.
 451             // Currently, we model this, by generating a sink.
 452             Bldr.generateSink(CastE, Pred, state);
 453             continue;
 454           } else {
 455             // If the cast fails on a pointer, bind to 0.
 456             state = state->BindExpr(CastE, LCtx,
 457                                     svalBuilder.makeNullWithType(resultType));
 458           }
 459         } else {
 460           // If we don't know if the cast succeeded, conjure a new symbol.
 461           if (val.isUnknown()) {
 462             DefinedOrUnknownSVal NewSym =
 463               svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx, resultType,
 464                                            currBldrCtx->blockCount());
 465             state = state->BindExpr(CastE, LCtx, NewSym);
 466           } else
 467             // Else, bind to the derived region value.
 468             state = state->BindExpr(CastE, LCtx, val);
 469         }
 470         Bldr.generateNode(CastE, Pred, state);
 471         continue;
 472       }
 473       case CK_BaseToDerived: {
 474         SVal val = state->getSVal(Ex, LCtx);
 475         QualType resultType = CastE->getType();
 476         if (CastE->isGLValue())
 477           resultType = getContext().getPointerType(resultType);
 478
 479         if (!val.isConstant()) {
 480           std::optional<SVal> V = getStoreManager().evalBaseToDerived(val, T);
 481           val = V ? *V : UnknownVal();
 482         }
 483
 484         // Failed to cast or the result is unknown, fall back to conservative.
 485         if (val.isUnknown()) {
 486           val =
 487             svalBuilder.conjureSymbolVal(nullptr, CastE, LCtx, resultType,
 488                                          currBldrCtx->blockCount());
 489         }
 490         state = state->BindExpr(CastE, LCtx, val);
 491         Bldr.generateNode(CastE, Pred, state);
 492         continue;
 493       }
 494       case CK_NullToPointer: {
 495         SVal V = svalBuilder.makeNullWithType(CastE->getType());
 496         state = state->BindExpr(CastE, LCtx, V);
 497         Bldr.generateNode(CastE, Pred, state);
 498         continue;
 499       }
 500       case CK_NullToMemberPointer: {
 501         SVal V = svalBuilder.getMemberPointer(nullptr);
 502         state = state->BindExpr(CastE, LCtx, V);
 503         Bldr.generateNode(CastE, Pred, state);
 504         continue;
 505       }
 506       case CK_DerivedToBaseMemberPointer:
 507       case CK_BaseToDerivedMemberPointer:
 508       case CK_ReinterpretMemberPointer: {
 509         SVal V = state->getSVal(Ex, LCtx);
 510         if (auto PTMSV = V.getAs<nonloc::PointerToMember>()) {
 511           SVal CastedPTMSV =
 512               svalBuilder.makePointerToMember(getBasicVals().accumCXXBase(
 513                   CastE->path(), *PTMSV, CastE->getCastKind()));
 514           state = state->BindExpr(CastE, LCtx, CastedPTMSV);
 515           Bldr.generateNode(CastE, Pred, state);
 516           continue;
 517         }
 518         // Explicitly proceed with default handler for this case cascade.
 519       }
 520         [[fallthrough]];
 521       // Various C++ casts that are not handled yet.
 522       case CK_ToUnion:
 523       case CK_MatrixCast:
 524       case CK_VectorSplat:
 525       case CK_HLSLVectorTruncation: {
 526         QualType resultType = CastE->getType();
 527         if (CastE->isGLValue())
 528           resultType = getContext().getPointerType(resultType);
 529         SVal result = svalBuilder.conjureSymbolVal(
 530             /*symbolTag=*/nullptr, CastE, LCtx, resultType,
 531             currBldrCtx->blockCount());
 532         state = state->BindExpr(CastE, LCtx, result);
 533         Bldr.generateNode(CastE, Pred, state);
 534         continue;
 535       }
 536     }
 537   }
 538 }
 539
 540 void ExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr *CL,
 541                                           ExplodedNode *Pred,
 542                                           ExplodedNodeSet &Dst) {
 543   StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
 544
 545   ProgramStateRef State = Pred->getState();
 546   const LocationContext *LCtx = Pred->getLocationContext();
 547
 548   const Expr *Init = CL->getInitializer();
 549   SVal V = State->getSVal(CL->getInitializer(), LCtx);
 550
 551   if (isa<CXXConstructExpr, CXXStdInitializerListExpr>(Init)) {
 552     // No work needed. Just pass the value up to this expression.
 553   } else {
 554     assert(isa<InitListExpr>(Init));
 555     Loc CLLoc = State->getLValue(CL, LCtx);
 556     State = State->bindLoc(CLLoc, V, LCtx);
 557
 558     if (CL->isGLValue())
 559       V = CLLoc;
 560   }
 561
 562   B.generateNode(CL, Pred, State->BindExpr(CL, LCtx, V));
 563 }
 564
 565 void ExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred,
 566                                ExplodedNodeSet &Dst) {
 567   if (isa<TypedefNameDecl>(*DS->decl_begin())) {
 568     // C99 6.7.7 "Any array size expressions associated with variable length
 569     // array declarators are evaluated each time the declaration of the typedef
 570     // name is reached in the order of execution."
 571     // The checkers should know about typedef to be able to handle VLA size
 572     // expressions.
 573     ExplodedNodeSet DstPre;
 574     getCheckerManager().runCheckersForPreStmt(DstPre, Pred, DS, *this);
 575     getCheckerManager().runCheckersForPostStmt(Dst, DstPre, DS, *this);
 576     return;
 577   }
 578
 579   // Assumption: The CFG has one DeclStmt per Decl.
 580   const VarDecl *VD = dyn_cast_or_null<VarDecl>(*DS->decl_begin());
 581
 582   if (!VD) {
 583     //TODO:AZ: remove explicit insertion after refactoring is done.
 584     Dst.insert(Pred);
 585     return;
 586   }
 587
 588   // FIXME: all pre/post visits should eventually be handled by ::Visit().
 589   ExplodedNodeSet dstPreVisit;
 590   getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, DS, *this);
 591
 592   ExplodedNodeSet dstEvaluated;
 593   StmtNodeBuilder B(dstPreVisit, dstEvaluated, *currBldrCtx);
 594   for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end();
 595        I!=E; ++I) {
 596     ExplodedNode *N = *I;
 597     ProgramStateRef state = N->getState();
 598     const LocationContext *LC = N->getLocationContext();
 599
 600     // Decls without InitExpr are not initialized explicitly.
 601     if (const Expr *InitEx = VD->getInit()) {
 602
 603       // Note in the state that the initialization has occurred.
 604       ExplodedNode *UpdatedN = N;
 605       SVal InitVal = state->getSVal(InitEx, LC);
 606
 607       assert(DS->isSingleDecl());
 608       if (getObjectUnderConstruction(state, DS, LC)) {
 609         state = finishObjectConstruction(state, DS, LC);
 610         // We constructed the object directly in the variable.
 611         // No need to bind anything.
 612         B.generateNode(DS, UpdatedN, state);
 613       } else {
 614         // Recover some path-sensitivity if a scalar value evaluated to
 615         // UnknownVal.
 616         if (InitVal.isUnknown()) {
 617           QualType Ty = InitEx->getType();
 618           if (InitEx->isGLValue()) {
 619             Ty = getContext().getPointerType(Ty);
 620           }
 621
 622           InitVal = svalBuilder.conjureSymbolVal(nullptr, InitEx, LC, Ty,
 623                                                  currBldrCtx->blockCount());
 624         }
 625
 626
 627         B.takeNodes(UpdatedN);
 628         ExplodedNodeSet Dst2;
 629         evalBind(Dst2, DS, UpdatedN, state->getLValue(VD, LC), InitVal, true);
 630         B.addNodes(Dst2);
 631       }
 632     }
 633     else {
 634       B.generateNode(DS, N, state);
 635     }
 636   }
 637
 638   getCheckerManager().runCheckersForPostStmt(Dst, B.getResults(), DS, *this);
 639 }
 640
 641 void ExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode *Pred,
 642                                   ExplodedNodeSet &Dst) {
 643   // This method acts upon CFG elements for logical operators && and ||
 644   // and attaches the value (true or false) to them as expressions.
 645   // It doesn't produce any state splits.
 646   // If we made it that far, we're past the point when we modeled the short
 647   // circuit. It means that we should have precise knowledge about whether
 648   // we've short-circuited. If we did, we already know the value we need to
 649   // bind. If we didn't, the value of the RHS (casted to the boolean type)
 650   // is the answer.
 651   // Currently this method tries to figure out whether we've short-circuited
 652   // by looking at the ExplodedGraph. This method is imperfect because there
 653   // could inevitably have been merges that would have resulted in multiple
 654   // potential path traversal histories. We bail out when we fail.
 655   // Due to this ambiguity, a more reliable solution would have been to
 656   // track the short circuit operation history path-sensitively until
 657   // we evaluate the respective logical operator.
 658   assert(B->getOpcode() == BO_LAnd ||
 659          B->getOpcode() == BO_LOr);
 660
 661   StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);
 662   ProgramStateRef state = Pred->getState();
 663
 664   if (B->getType()->isVectorType()) {
 665     // FIXME: We do not model vector arithmetic yet. When adding support for
 666     // that, note that the CFG-based reasoning below does not apply, because
 667     // logical operators on vectors are not short-circuit. Currently they are
 668     // modeled as short-circuit in Clang CFG but this is incorrect.
 669     // Do not set the value for the expression. It'd be UnknownVal by default.
 670     Bldr.generateNode(B, Pred, state);
 671     return;
 672   }
 673
 674   ExplodedNode *N = Pred;
 675   while (!N->getLocation().getAs<BlockEntrance>()) {
 676     ProgramPoint P = N->getLocation();
 677     assert(P.getAs<PreStmt>()|| P.getAs<PreStmtPurgeDeadSymbols>());
 678     (void) P;
 679     if (N->pred_size() != 1) {
 680       // We failed to track back where we came from.
 681       Bldr.generateNode(B, Pred, state);
 682       return;
 683     }
 684     N = *N->pred_begin();
 685   }
 686
 687   if (N->pred_size() != 1) {
 688     // We failed to track back where we came from.
 689     Bldr.generateNode(B, Pred, state);
 690     return;
 691   }
 692
 693   N = *N->pred_begin();
 694   BlockEdge BE = N->getLocation().castAs<BlockEdge>();
 695   SVal X;
 696
 697   // Determine the value of the expression by introspecting how we
 698   // got this location in the CFG.  This requires looking at the previous
 699   // block we were in and what kind of control-flow transfer was involved.
 700   const CFGBlock *SrcBlock = BE.getSrc();
 701   // The only terminator (if there is one) that makes sense is a logical op.
 702   CFGTerminator T = SrcBlock->getTerminator();
 703   if (const BinaryOperator *Term = cast_or_null<BinaryOperator>(T.getStmt())) {
 704     (void) Term;
 705     assert(Term->isLogicalOp());
 706     assert(SrcBlock->succ_size() == 2);
 707     // Did we take the true or false branch?
 708     unsigned constant = (*SrcBlock->succ_begin() == BE.getDst()) ? 1 : 0;
 709     X = svalBuilder.makeIntVal(constant, B->getType());
 710   }
 711   else {
 712     // If there is no terminator, by construction the last statement
 713     // in SrcBlock is the value of the enclosing expression.
 714     // However, we still need to constrain that value to be 0 or 1.
 715     assert(!SrcBlock->empty());
 716     CFGStmt Elem = SrcBlock->rbegin()->castAs<CFGStmt>();
 717     const Expr *RHS = cast<Expr>(Elem.getStmt());
 718     SVal RHSVal = N->getState()->getSVal(RHS, Pred->getLocationContext());
 719
 720     if (RHSVal.isUndef()) {
 721       X = RHSVal;
 722     } else {
 723       // We evaluate "RHSVal != 0" expression which result in 0 if the value is
 724       // known to be false, 1 if the value is known to be true and a new symbol
 725       // when the assumption is unknown.
 726       nonloc::ConcreteInt Zero(getBasicVals().getValue(0, B->getType()));
 727       X = evalBinOp(N->getState(), BO_NE,
 728                     svalBuilder.evalCast(RHSVal, B->getType(), RHS->getType()),
 729                     Zero, B->getType());
 730     }
 731   }
 732   Bldr.generateNode(B, Pred, state->BindExpr(B, Pred->getLocationContext(), X));
 733 }
 734
 735 void ExprEngine::VisitInitListExpr(const InitListExpr *IE,
 736                                    ExplodedNode *Pred,
 737                                    ExplodedNodeSet &Dst) {
 738   StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
 739
 740   ProgramStateRef state = Pred->getState();
 741   const LocationContext *LCtx = Pred->getLocationContext();
 742   QualType T = getContext().getCanonicalType(IE->getType());
 743   unsigned NumInitElements = IE->getNumInits();
 744
 745   if (!IE->isGLValue() && !IE->isTransparent() &&
 746       (T->isArrayType() || T->isRecordType() || T->isVectorType() ||
 747        T->isAnyComplexType())) {
 748     llvm::ImmutableList<SVal> vals = getBasicVals().getEmptySValList();
 749
 750     // Handle base case where the initializer has no elements.
 751     // e.g: static int* myArray[] = {};
 752     if (NumInitElements == 0) {
 753       SVal V = svalBuilder.makeCompoundVal(T, vals);
 754       B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
 755       return;
 756     }
 757
 758     for (const Stmt *S : llvm::reverse(*IE)) {
 759       SVal V = state->getSVal(cast<Expr>(S), LCtx);
 760       vals = getBasicVals().prependSVal(V, vals);
 761     }
 762
 763     B.generateNode(IE, Pred,
 764                    state->BindExpr(IE, LCtx,
 765                                    svalBuilder.makeCompoundVal(T, vals)));
 766     return;
 767   }
 768
 769   // Handle scalars: int{5} and int{} and GLvalues.
 770   // Note, if the InitListExpr is a GLvalue, it means that there is an address
 771   // representing it, so it must have a single init element.
 772   assert(NumInitElements <= 1);
 773
 774   SVal V;
 775   if (NumInitElements == 0)
 776     V = getSValBuilder().makeZeroVal(T);
 777   else
 778     V = state->getSVal(IE->getInit(0), LCtx);
 779
 780   B.generateNode(IE, Pred, state->BindExpr(IE, LCtx, V));
 781 }
 782
 783 void ExprEngine::VisitGuardedExpr(const Expr *Ex,
 784                                   const Expr *L,
 785                                   const Expr *R,
 786                                   ExplodedNode *Pred,
 787                                   ExplodedNodeSet &Dst) {
 788   assert(L && R);
 789
 790   StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
 791   ProgramStateRef state = Pred->getState();
 792   const LocationContext *LCtx = Pred->getLocationContext();
 793   const CFGBlock *SrcBlock = nullptr;
 794
 795   // Find the predecessor block.
 796   ProgramStateRef SrcState = state;
 797   for (const ExplodedNode *N = Pred ; N ; N = *N->pred_begin()) {
 798     ProgramPoint PP = N->getLocation();
 799     if (PP.getAs<PreStmtPurgeDeadSymbols>() || PP.getAs<BlockEntrance>()) {
 800       // If the state N has multiple predecessors P, it means that successors
 801       // of P are all equivalent.
 802       // In turn, that means that all nodes at P are equivalent in terms
 803       // of observable behavior at N, and we can follow any of them.
 804       // FIXME: a more robust solution which does not walk up the tree.
 805       continue;
 806     }
 807     SrcBlock = PP.castAs<BlockEdge>().getSrc();
 808     SrcState = N->getState();
 809     break;
 810   }
 811
 812   assert(SrcBlock && "missing function entry");
 813
 814   // Find the last expression in the predecessor block.  That is the
 815   // expression that is used for the value of the ternary expression.
 816   bool hasValue = false;
 817   SVal V;
 818
 819   for (CFGElement CE : llvm::reverse(*SrcBlock)) {
 820     if (std::optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
 821       const Expr *ValEx = cast<Expr>(CS->getStmt());
 822       ValEx = ValEx->IgnoreParens();
 823
 824       // For GNU extension '?:' operator, the left hand side will be an
 825       // OpaqueValueExpr, so get the underlying expression.
 826       if (const OpaqueValueExpr *OpaqueEx = dyn_cast<OpaqueValueExpr>(L))
 827         L = OpaqueEx->getSourceExpr();
 828
 829       // If the last expression in the predecessor block matches true or false
 830       // subexpression, get its the value.
 831       if (ValEx == L->IgnoreParens() || ValEx == R->IgnoreParens()) {
 832         hasValue = true;
 833         V = SrcState->getSVal(ValEx, LCtx);
 834       }
 835       break;
 836     }
 837   }
 838
 839   if (!hasValue)
 840     V = svalBuilder.conjureSymbolVal(nullptr, Ex, LCtx,
 841                                      currBldrCtx->blockCount());
 842
 843   // Generate a new node with the binding from the appropriate path.
 844   B.generateNode(Ex, Pred, state->BindExpr(Ex, LCtx, V, true));
 845 }
 846
 847 void ExprEngine::
 848 VisitOffsetOfExpr(const OffsetOfExpr *OOE,
 849                   ExplodedNode *Pred, ExplodedNodeSet &Dst) {
 850   StmtNodeBuilder B(Pred, Dst, *currBldrCtx);
 851   Expr::EvalResult Result;
 852   if (OOE->EvaluateAsInt(Result, getContext())) {
 853     APSInt IV = Result.Val.getInt();
 854     assert(IV.getBitWidth() == getContext().getTypeSize(OOE->getType()));
 855     assert(OOE->getType()->castAs<BuiltinType>()->isInteger());
 856     assert(IV.isSigned() == OOE->getType()->isSignedIntegerType());
 857     SVal X = svalBuilder.makeIntVal(IV);
 858     B.generateNode(OOE, Pred,
 859                    Pred->getState()->BindExpr(OOE, Pred->getLocationContext(),
 860                                               X));
 861   }
 862   // FIXME: Handle the case where __builtin_offsetof is not a constant.
 863 }
 864
 865
 866 void ExprEngine::
 867 VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex,
 868                               ExplodedNode *Pred,
 869                               ExplodedNodeSet &Dst) {
 870   // FIXME: Prechecks eventually go in ::Visit().
 871   ExplodedNodeSet CheckedSet;
 872   getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, Ex, *this);
 873
 874   ExplodedNodeSet EvalSet;
 875   StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
 876
 877   QualType T = Ex->getTypeOfArgument();
 878
 879   for (ExplodedNode *N : CheckedSet) {
 880     if (Ex->getKind() == UETT_SizeOf) {
 881       if (!T->isIncompleteType() && !T->isConstantSizeType()) {
 882         assert(T->isVariableArrayType() && "Unknown non-constant-sized type.");
 883
 884         // FIXME: Add support for VLA type arguments and VLA expressions.
 885         // When that happens, we should probably refactor VLASizeChecker's code.
 886         continue;
 887       } else if (T->getAs<ObjCObjectType>()) {
 888         // Some code tries to take the sizeof an ObjCObjectType, relying that
 889         // the compiler has laid out its representation.  Just report Unknown
 890         // for these.
 891         continue;
 892       }
 893     }
 894
 895     APSInt Value = Ex->EvaluateKnownConstInt(getContext());
 896     CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue());
 897
 898     ProgramStateRef state = N->getState();
 899     state = state->BindExpr(
 900         Ex, N->getLocationContext(),
 901         svalBuilder.makeIntVal(amt.getQuantity(), Ex->getType()));
 902     Bldr.generateNode(Ex, N, state);
 903   }
 904
 905   getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, Ex, *this);
 906 }
 907
 908 void ExprEngine::handleUOExtension(ExplodedNode *N, const UnaryOperator *U,
 909                                    StmtNodeBuilder &Bldr) {
 910   // FIXME: We can probably just have some magic in Environment::getSVal()
 911   // that propagates values, instead of creating a new node here.
 912   //
 913   // Unary "+" is a no-op, similar to a parentheses.  We still have places
 914   // where it may be a block-level expression, so we need to
 915   // generate an extra node that just propagates the value of the
 916   // subexpression.
 917   const Expr *Ex = U->getSubExpr()->IgnoreParens();
 918   ProgramStateRef state = N->getState();
 919   const LocationContext *LCtx = N->getLocationContext();
 920   Bldr.generateNode(U, N, state->BindExpr(U, LCtx, state->getSVal(Ex, LCtx)));
 921 }
 922
 923 void ExprEngine::VisitUnaryOperator(const UnaryOperator* U, ExplodedNode *Pred,
 924                                     ExplodedNodeSet &Dst) {
 925   // FIXME: Prechecks eventually go in ::Visit().
 926   ExplodedNodeSet CheckedSet;
 927   getCheckerManager().runCheckersForPreStmt(CheckedSet, Pred, U, *this);
 928
 929   ExplodedNodeSet EvalSet;
 930   StmtNodeBuilder Bldr(CheckedSet, EvalSet, *currBldrCtx);
 931
 932   for (ExplodedNode *N : CheckedSet) {
 933     switch (U->getOpcode()) {
 934     default: {
 935       Bldr.takeNodes(N);
 936       ExplodedNodeSet Tmp;
 937       VisitIncrementDecrementOperator(U, N, Tmp);
 938       Bldr.addNodes(Tmp);
 939       break;
 940     }
 941     case UO_Real: {
 942       const Expr *Ex = U->getSubExpr()->IgnoreParens();
 943
 944       // FIXME: We don't have complex SValues yet.
 945       if (Ex->getType()->isAnyComplexType()) {
 946         // Just report "Unknown."
 947         break;
 948       }
 949
 950       // For all other types, UO_Real is an identity operation.
 951       assert (U->getType() == Ex->getType());
 952       ProgramStateRef state = N->getState();
 953       const LocationContext *LCtx = N->getLocationContext();
 954       Bldr.generateNode(U, N,
 955                         state->BindExpr(U, LCtx, state->getSVal(Ex, LCtx)));
 956       break;
 957     }
 958
 959     case UO_Imag: {
 960       const Expr *Ex = U->getSubExpr()->IgnoreParens();
 961       // FIXME: We don't have complex SValues yet.
 962       if (Ex->getType()->isAnyComplexType()) {
 963         // Just report "Unknown."
 964         break;
 965       }
 966       // For all other types, UO_Imag returns 0.
 967       ProgramStateRef state = N->getState();
 968       const LocationContext *LCtx = N->getLocationContext();
 969       SVal X = svalBuilder.makeZeroVal(Ex->getType());
 970       Bldr.generateNode(U, N, state->BindExpr(U, LCtx, X));
 971       break;
 972     }
 973
 974     case UO_AddrOf: {
 975       // Process pointer-to-member address operation.
 976       const Expr *Ex = U->getSubExpr()->IgnoreParens();
 977       if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Ex)) {
 978         const ValueDecl *VD = DRE->getDecl();
 979
 980         if (isa<CXXMethodDecl, FieldDecl, IndirectFieldDecl>(VD)) {
 981           ProgramStateRef State = N->getState();
 982           const LocationContext *LCtx = N->getLocationContext();
 983           SVal SV = svalBuilder.getMemberPointer(cast<NamedDecl>(VD));
 984           Bldr.generateNode(U, N, State->BindExpr(U, LCtx, SV));
 985           break;
 986         }
 987       }
 988       // Explicitly proceed with default handler for this case cascade.
 989       handleUOExtension(N, U, Bldr);
 990       break;
 991     }
 992     case UO_Plus:
 993       assert(!U->isGLValue());
 994       [[fallthrough]];
 995     case UO_Deref:
 996     case UO_Extension: {
 997       handleUOExtension(N, U, Bldr);
 998       break;
 999     }
1000
1001     case UO_LNot:
1002     case UO_Minus:
1003     case UO_Not: {
1004       assert (!U->isGLValue());
1005       const Expr *Ex = U->getSubExpr()->IgnoreParens();
1006       ProgramStateRef state = N->getState();
1007       const LocationContext *LCtx = N->getLocationContext();
1008
1009       // Get the value of the subexpression.
1010       SVal V = state->getSVal(Ex, LCtx);
1011
1012       if (V.isUnknownOrUndef()) {
1013         Bldr.generateNode(U, N, state->BindExpr(U, LCtx, V));
1014         break;
1015       }
1016
1017       switch (U->getOpcode()) {
1018         default:
1019           llvm_unreachable("Invalid Opcode.");
1020         case UO_Not:
1021           // FIXME: Do we need to handle promotions?
1022           state = state->BindExpr(
1023               U, LCtx, svalBuilder.evalComplement(V.castAs<NonLoc>()));
1024           break;
1025         case UO_Minus:
1026           // FIXME: Do we need to handle promotions?
1027           state = state->BindExpr(U, LCtx,
1028                                   svalBuilder.evalMinus(V.castAs<NonLoc>()));
1029           break;
1030         case UO_LNot:
1031           // C99 6.5.3.3: "The expression !E is equivalent to (0==E)."
1032           //
1033           //  Note: technically we do "E == 0", but this is the same in the
1034           //    transfer functions as "0 == E".
1035           SVal Result;
1036           if (std::optional<Loc> LV = V.getAs<Loc>()) {
1037           Loc X = svalBuilder.makeNullWithType(Ex->getType());
1038           Result = evalBinOp(state, BO_EQ, *LV, X, U->getType());
1039           } else if (Ex->getType()->isFloatingType()) {
1040           // FIXME: handle floating point types.
1041           Result = UnknownVal();
1042           } else {
1043           nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType()));
1044           Result = evalBinOp(state, BO_EQ, V.castAs<NonLoc>(), X, U->getType());
1045           }
1046
1047           state = state->BindExpr(U, LCtx, Result);
1048           break;
1049       }
1050       Bldr.generateNode(U, N, state);
1051       break;
1052     }
1053     }
1054   }
1055
1056   getCheckerManager().runCheckersForPostStmt(Dst, EvalSet, U, *this);
1057 }
1058
1059 void ExprEngine::VisitIncrementDecrementOperator(const UnaryOperator* U,
1060                                                  ExplodedNode *Pred,
1061                                                  ExplodedNodeSet &Dst) {
1062   // Handle ++ and -- (both pre- and post-increment).
1063   assert (U->isIncrementDecrementOp());
1064   const Expr *Ex = U->getSubExpr()->IgnoreParens();
1065
1066   const LocationContext *LCtx = Pred->getLocationContext();
1067   ProgramStateRef state = Pred->getState();
1068   SVal loc = state->getSVal(Ex, LCtx);
1069
1070   // Perform a load.
1071   ExplodedNodeSet Tmp;
1072   evalLoad(Tmp, U, Ex, Pred, state, loc);
1073
1074   ExplodedNodeSet Dst2;
1075   StmtNodeBuilder Bldr(Tmp, Dst2, *currBldrCtx);
1076   for (ExplodedNode *N : Tmp) {
1077     state = N->getState();
1078     assert(LCtx == N->getLocationContext());
1079     SVal V2_untested = state->getSVal(Ex, LCtx);
1080
1081     // Propagate unknown and undefined values.
1082     if (V2_untested.isUnknownOrUndef()) {
1083       state = state->BindExpr(U, LCtx, V2_untested);
1084
1085       // Perform the store, so that the uninitialized value detection happens.
1086       Bldr.takeNodes(N);
1087       ExplodedNodeSet Dst3;
1088       evalStore(Dst3, U, Ex, N, state, loc, V2_untested);
1089       Bldr.addNodes(Dst3);
1090
1091       continue;
1092     }
1093     DefinedSVal V2 = V2_untested.castAs<DefinedSVal>();
1094
1095     // Handle all other values.
1096     BinaryOperator::Opcode Op = U->isIncrementOp() ? BO_Add : BO_Sub;
1097
1098     // If the UnaryOperator has non-location type, use its type to create the
1099     // constant value. If the UnaryOperator has location type, create the
1100     // constant with int type and pointer width.
1101     SVal RHS;
1102     SVal Result;
1103
1104     if (U->getType()->isAnyPointerType())
1105       RHS = svalBuilder.makeArrayIndex(1);
1106     else if (U->getType()->isIntegralOrEnumerationType())
1107       RHS = svalBuilder.makeIntVal(1, U->getType());
1108     else
1109       RHS = UnknownVal();
1110
1111     // The use of an operand of type bool with the ++ operators is deprecated
1112     // but valid until C++17. And if the operand of the ++ operator is of type
1113     // bool, it is set to true until C++17. Note that for '_Bool', it is also
1114     // set to true when it encounters ++ operator.
1115     if (U->getType()->isBooleanType() && U->isIncrementOp())
1116       Result = svalBuilder.makeTruthVal(true, U->getType());
1117     else
1118       Result = evalBinOp(state, Op, V2, RHS, U->getType());
1119
1120     // Conjure a new symbol if necessary to recover precision.
1121     if (Result.isUnknown()){
1122       DefinedOrUnknownSVal SymVal =
1123         svalBuilder.conjureSymbolVal(nullptr, U, LCtx,
1124                                      currBldrCtx->blockCount());
1125       Result = SymVal;
1126
1127       // If the value is a location, ++/-- should always preserve
1128       // non-nullness.  Check if the original value was non-null, and if so
1129       // propagate that constraint.
1130       if (Loc::isLocType(U->getType())) {
1131         DefinedOrUnknownSVal Constraint =
1132         svalBuilder.evalEQ(state, V2,svalBuilder.makeZeroVal(U->getType()));
1133
1134         if (!state->assume(Constraint, true)) {
1135           // It isn't feasible for the original value to be null.
1136           // Propagate this constraint.
1137           Constraint = svalBuilder.evalEQ(state, SymVal,
1138                                        svalBuilder.makeZeroVal(U->getType()));
1139
1140           state = state->assume(Constraint, false);
1141           assert(state);
1142         }
1143       }
1144     }
1145
1146     // Since the lvalue-to-rvalue conversion is explicit in the AST,
1147     // we bind an l-value if the operator is prefix and an lvalue (in C++).
1148     if (U->isGLValue())
1149       state = state->BindExpr(U, LCtx, loc);
1150     else
1151       state = state->BindExpr(U, LCtx, U->isPostfix() ? V2 : Result);
1152
1153     // Perform the store.
1154     Bldr.takeNodes(N);
1155     ExplodedNodeSet Dst3;
1156     evalStore(Dst3, U, Ex, N, state, loc, Result);
1157     Bldr.addNodes(Dst3);
1158   }
1159   Dst.insert(Dst2);
1160 }