//=-- ExprEngineCallAndReturn.cpp - Support for call/return -----*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

//  This file defines ExprEngine's support for calls and returns.

//

//===----------------------------------------------------------------------===//

#include "PrettyStackTraceLocationContext.h"

#include "clang/AST/CXXInheritance.h"

#include "clang/AST/Decl.h"

#include "clang/AST/DeclCXX.h"

#include "clang/Analysis/Analyses/LiveVariables.h"

#include "clang/Analysis/ConstructionContext.h"

#include "clang/StaticAnalyzer/Core/CheckerManager.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"

#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"

#include "llvm/ADT/SmallSet.h"

#include "llvm/ADT/Statistic.h"

#include "llvm/Support/Casting.h"

#include "llvm/Support/Compiler.h"

#include "llvm/Support/SaveAndRestore.h"

using namespace clang;

using namespace ento;

#define DEBUG_TYPE "ExprEngine"

STATISTIC(NumOfDynamicDispatchPathSplits,

  "The # of times we split the path due to imprecise dynamic dispatch info");

STATISTIC(NumInlinedCalls,

  "The # of times we inlined a call");

STATISTIC(NumReachedInlineCountMax,

  "The # of times we reached inline count maximum");

void ExprEngine::processCallEnter(NodeBuilderContext& BC, CallEnter CE,

                                  ExplodedNode *Pred) {

  // Get the entry block in the CFG of the callee.

  const StackFrameContext *calleeCtx = CE.getCalleeContext();

  PrettyStackTraceLocationContext CrashInfo(calleeCtx);

  const CFGBlock *Entry = CE.getEntry();

  // Validate the CFG.

  assert(Entry->empty());

  assert(Entry->succ_size() == 1);

  // Get the solitary successor.

  const CFGBlock *Succ = *(Entry->succ_begin());

  // Construct an edge representing the starting location in the callee.

  BlockEdge Loc(Entry, Succ, calleeCtx);

  ProgramStateRef state = Pred->getState();

  // Construct a new node, notify checkers that analysis of the function has

  // begun, and add the resultant nodes to the worklist.

  bool isNew;

  ExplodedNode *Node = G.getNode(Loc, state, false, &isNew);

  Node->addPredecessor(Pred, G);

  if (isNew) {

    ExplodedNodeSet DstBegin;

    processBeginOfFunction(BC, Node, DstBegin, Loc);

    Engine.enqueue(DstBegin);

  }

}

// Find the last statement on the path to the exploded node and the

// corresponding Block.

static std::pair<const Stmt*,

                 const CFGBlock*> getLastStmt(const ExplodedNode *Node) {

  const Stmt *S = nullptr;

  const CFGBlock *Blk = nullptr;

  const StackFrameContext *SF = Node->getStackFrame();

  // Back up through the ExplodedGraph until we reach a statement node in this

  // stack frame.

  while (Node) {

    const ProgramPoint &PP = Node->getLocation();

    if (PP.getStackFrame() == SF) {

      if (Optional<StmtPoint> SP = PP.getAs<StmtPoint>()) {

        S = SP->getStmt();

        break;

      } else if (Optional<CallExitEnd> CEE = PP.getAs<CallExitEnd>()) {

        S = CEE->getCalleeContext()->getCallSite();

        if (S)

          break;

        // If there is no statement, this is an implicitly-generated call.

        // We'll walk backwards over it and then continue the loop to find

        // an actual statement.

        Optional<CallEnter> CE;

        do {

          Node = Node->getFirstPred();

          CE = Node->getLocationAs<CallEnter>();

        } while (!CE || 
CE->getCalleeContext() != CEE->getCalleeContext()534
);

        // Continue searching the graph.

      } else if (Optional<BlockEdge> BE = PP.getAs<BlockEdge>()) {

        Blk = BE->getSrc();

      }

    } else if (Optional<CallEnter> CE = PP.getAs<CallEnter>()) {

      // If we reached the CallEnter for this function, it has no statements.

      if (CE->getCalleeContext() == SF)

        break;

    }

    if (Node->pred_empty())

      return std::make_pair(nullptr, nullptr);

    Node = *Node->pred_begin();

  }

  return std::make_pair(S, Blk);

}

/// Adjusts a return value when the called function's return type does not

/// match the caller's expression type. This can happen when a dynamic call

/// is devirtualized, and the overriding method has a covariant (more specific)

/// return type than the parent's method. For C++ objects, this means we need

/// to add base casts.

static SVal adjustReturnValue(SVal V, QualType ExpectedTy, QualType ActualTy,

                              StoreManager &StoreMgr) {

  // For now, the only adjustments we handle apply only to locations.

  if (!V.getAs<Loc>())

    return V;

  // If the types already match, don't do any unnecessary work.

  ExpectedTy = ExpectedTy.getCanonicalType();

  ActualTy = ActualTy.getCanonicalType();

  if (ExpectedTy == ActualTy)

    return V;

  // No adjustment is needed between Objective-C pointer types.

  if (ExpectedTy->isObjCObjectPointerType() &&

      ActualTy->isObjCObjectPointerType())

    return V;

  // C++ object pointers may need "derived-to-base" casts.

  const CXXRecordDecl *ExpectedClass = ExpectedTy->getPointeeCXXRecordDecl();

  const CXXRecordDecl *ActualClass = ActualTy->getPointeeCXXRecordDecl();

  if (ExpectedClass && 
ActualClass1
) {

    CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,

                       /*DetectVirtual=*/false);

    if (ActualClass->isDerivedFrom(ExpectedClass, Paths) &&

        !Paths.isAmbiguous(ActualTy->getCanonicalTypeUnqualified())) {

      return StoreMgr.evalDerivedToBase(V, Paths.front());

    }

  }

  // Unfortunately, Objective-C does not enforce that overridden methods have

  // covariant return types, so we can't assert that that never happens.

  // Be safe and return UnknownVal().

  return UnknownVal();

}

void ExprEngine::removeDeadOnEndOfFunction(NodeBuilderContext& BC,

                                           ExplodedNode *Pred,

                                           ExplodedNodeSet &Dst) {

  // Find the last statement in the function and the corresponding basic block.

  const Stmt *LastSt = nullptr;

  const CFGBlock *Blk = nullptr;

  std::tie(LastSt, Blk) = getLastStmt(Pred);

  if (!Blk || 
!LastSt21.2k
) {

    Dst.Add(Pred);

    return;

  }

  // Here, we destroy the current location context. We use the current

  // function's entire body as a diagnostic statement, with which the program

  // point will be associated. However, we only want to use LastStmt as a

  // reference for what to clean up if it's a ReturnStmt; otherwise, everything

  // is dead.

  SaveAndRestore<const NodeBuilderContext *> NodeContextRAII(currBldrCtx, &BC);

  const LocationContext *LCtx = Pred->getLocationContext();

  removeDead(Pred, Dst, dyn_cast<ReturnStmt>(LastSt), LCtx,

             LCtx->getAnalysisDeclContext()->getBody(),

             ProgramPoint::PostStmtPurgeDeadSymbolsKind);

}

static bool wasDifferentDeclUsedForInlining(CallEventRef<> Call,

    const StackFrameContext *calleeCtx) {

  const Decl *RuntimeCallee = calleeCtx->getDecl();

  const Decl *StaticDecl = Call->getDecl();

  assert(RuntimeCallee);

  if (!StaticDecl)

    return true;

  return RuntimeCallee->getCanonicalDecl() != StaticDecl->getCanonicalDecl();

}

/// The call exit is simulated with a sequence of nodes, which occur between

/// CallExitBegin and CallExitEnd. The following operations occur between the

/// two program points:

/// 1. CallExitBegin (triggers the start of call exit sequence)

/// 2. Bind the return value

/// 3. Run Remove dead bindings to clean up the dead symbols from the callee.

/// 4. CallExitEnd (switch to the caller context)

/// 5. PostStmt<CallExpr>

void ExprEngine::processCallExit(ExplodedNode *CEBNode) {

  // Step 1 CEBNode was generated before the call.

  PrettyStackTraceLocationContext CrashInfo(CEBNode->getLocationContext());

  const StackFrameContext *calleeCtx = CEBNode->getStackFrame();

  // The parent context might not be a stack frame, so make sure we

  // look up the first enclosing stack frame.

  const StackFrameContext *callerCtx =

    calleeCtx->getParent()->getStackFrame();

  const Stmt *CE = calleeCtx->getCallSite();

  ProgramStateRef state = CEBNode->getState();

  // Find the last statement in the function and the corresponding basic block.

  const Stmt *LastSt = nullptr;

  const CFGBlock *Blk = nullptr;

  std::tie(LastSt, Blk) = getLastStmt(CEBNode);

  // Generate a CallEvent /before/ cleaning the state, so that we can get the

  // correct value for 'this' (if necessary).

  CallEventManager &CEMgr = getStateManager().getCallEventManager();

  CallEventRef<> Call = CEMgr.getCaller(calleeCtx, state);

  // Step 2: generate node with bound return value: CEBNode -> BindedRetNode.

  // If the callee returns an expression, bind its value to CallExpr.

  if (CE) {

    if (const ReturnStmt *RS = dyn_cast_or_null<ReturnStmt>(LastSt)) {

      const LocationContext *LCtx = CEBNode->getLocationContext();

      SVal V = state->getSVal(RS, LCtx);

      // Ensure that the return type matches the type of the returned Expr.

      if (wasDifferentDeclUsedForInlining(Call, calleeCtx)) {

        QualType ReturnedTy =

          CallEvent::getDeclaredResultType(calleeCtx->getDecl());

        if (!ReturnedTy.isNull()) {

          if (const Expr *Ex = dyn_cast<Expr>(CE)) {

            V = adjustReturnValue(V, Ex->getType(), ReturnedTy,

                                  getStoreManager());

          }

        }

      }

      state = state->BindExpr(CE, callerCtx, V);

    }

    // Bind the constructed object value to CXXConstructExpr.

    if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(CE)) {

      loc::MemRegionVal This =

        svalBuilder.getCXXThis(CCE->getConstructor()->getParent(), calleeCtx);

      SVal ThisV = state->getSVal(This);

      ThisV = state->getSVal(ThisV.castAs<Loc>());

      state = state->BindExpr(CCE, callerCtx, ThisV);

    }

    if (const auto *CNE = dyn_cast<CXXNewExpr>(CE)) {

      // We are currently evaluating a CXXNewAllocator CFGElement. It takes a

      // while to reach the actual CXXNewExpr element from here, so keep the

      // region for later use.

      // Additionally cast the return value of the inlined operator new

      // (which is of type 'void *') to the correct object type.

      SVal AllocV = state->getSVal(CNE, callerCtx);

      AllocV = svalBuilder.evalCast(

          AllocV, CNE->getType(),

          getContext().getPointerType(getContext().VoidTy));

      state = addObjectUnderConstruction(state, CNE, calleeCtx->getParent(),

                                         AllocV);

    }

  }

  // Step 3: BindedRetNode -> CleanedNodes

  // If we can find a statement and a block in the inlined function, run remove

  // dead bindings before returning from the call. This is important to ensure

  // that we report the issues such as leaks in the stack contexts in which

  // they occurred.

  ExplodedNodeSet CleanedNodes;

  if (LastSt && 
Blk37.8k
 && 
AMgr.options.AnalysisPurgeOpt != PurgeNone37.8k
) {

    static SimpleProgramPointTag retValBind("ExprEngine", "Bind Return Value");

    PostStmt Loc(LastSt, calleeCtx, &retValBind);

    bool isNew;

    ExplodedNode *BindedRetNode = G.getNode(Loc, state, false, &isNew);

    BindedRetNode->addPredecessor(CEBNode, G);

    if (!isNew)

      return;

    NodeBuilderContext Ctx(getCoreEngine(), Blk, BindedRetNode);

    currBldrCtx = &Ctx;

    // Here, we call the Symbol Reaper with 0 statement and callee location

    // context, telling it to clean up everything in the callee's context

    // (and its children). We use the callee's function body as a diagnostic

    // statement, with which the program point will be associated.

    removeDead(BindedRetNode, CleanedNodes, nullptr, calleeCtx,

               calleeCtx->getAnalysisDeclContext()->getBody(),

               ProgramPoint::PostStmtPurgeDeadSymbolsKind);

    currBldrCtx = nullptr;

  } else {

    CleanedNodes.Add(CEBNode);

  }

  for (ExplodedNodeSet::iterator I = CleanedNodes.begin(),

                                 E = CleanedNodes.end(); I != E; 
++I39.4k
) {

    // Step 4: Generate the CallExit and leave the callee's context.

    // CleanedNodes -> CEENode

    CallExitEnd Loc(calleeCtx, callerCtx);

    bool isNew;

    ProgramStateRef CEEState = (*I == CEBNode) ? 
state3.39k
 : 
(*I)->getState()36.0k
;

    ExplodedNode *CEENode = G.getNode(Loc, CEEState, false, &isNew);

    CEENode->addPredecessor(*I, G);

    if (!isNew)

      return;

    // Step 5: Perform the post-condition check of the CallExpr and enqueue the

    // result onto the work list.

    // CEENode -> Dst -> WorkList

    NodeBuilderContext Ctx(Engine, calleeCtx->getCallSiteBlock(), CEENode);

    SaveAndRestore<const NodeBuilderContext*> NBCSave(currBldrCtx,

        &Ctx);

    SaveAndRestore<unsigned> CBISave(currStmtIdx, calleeCtx->getIndex());

    CallEventRef<> UpdatedCall = Call.cloneWithState(CEEState);

    ExplodedNodeSet DstPostCall;

    if (llvm::isa_and_nonnull<CXXNewExpr>(CE)) {

      ExplodedNodeSet DstPostPostCallCallback;

      getCheckerManager().runCheckersForPostCall(DstPostPostCallCallback,

                                                 CEENode, *UpdatedCall, *this,

                                                 /*wasInlined=*/true);

      for (ExplodedNode *I : DstPostPostCallCallback) {

        getCheckerManager().runCheckersForNewAllocator(

            cast<CXXAllocatorCall>(*UpdatedCall), DstPostCall, I, *this,

            /*wasInlined=*/true);

      }

    } else {

      getCheckerManager().runCheckersForPostCall(DstPostCall, CEENode,

                                                 *UpdatedCall, *this,

                                                 /*wasInlined=*/true);

    }

    ExplodedNodeSet Dst;

    if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) {

      getCheckerManager().runCheckersForPostObjCMessage(Dst, DstPostCall, *Msg,

                                                        *this,

                                                        /*wasInlined=*/true);

    } else if (CE &&

               !(isa<CXXNewExpr>(CE) && // Called when visiting CXXNewExpr.

                 
AMgr.getAnalyzerOptions().MayInlineCXXAllocator366
)) {

      getCheckerManager().runCheckersForPostStmt(Dst, DstPostCall, CE,

                                                 *this, /*wasInlined=*/true);

    } else {

      Dst.insert(DstPostCall);

    }

    // Enqueue the next element in the block.

    for (ExplodedNodeSet::iterator PSI = Dst.begin(), PSE = Dst.end();

                                   PSI != PSE; 
++PSI39.4k
) {

      Engine.getWorkList()->enqueue(*PSI, calleeCtx->getCallSiteBlock(),

                                    calleeCtx->getIndex()+1);

    }

  }

}

bool ExprEngine::isSmall(AnalysisDeclContext *ADC) const {

  // When there are no branches in the function, it means that there's no

  // exponential complexity introduced by inlining such function.

  // Such functions also don't trigger various fundamental problems

  // with our inlining mechanism, such as the problem of

  // inlined defensive checks. Hence isLinear().

  const CFG *Cfg = ADC->getCFG();

  return Cfg->isLinear() || 
Cfg->size() <= AMgr.options.AlwaysInlineSize18.5k
;

}

bool ExprEngine::isLarge(AnalysisDeclContext *ADC) const {

  const CFG *Cfg = ADC->getCFG();

  return Cfg->size() >= AMgr.options.MinCFGSizeTreatFunctionsAsLarge;

}

bool ExprEngine::isHuge(AnalysisDeclContext *ADC) const {

  const CFG *Cfg = ADC->getCFG();

  return Cfg->getNumBlockIDs() > AMgr.options.MaxInlinableSize;

}

void ExprEngine::examineStackFrames(const Decl *D, const LocationContext *LCtx,

                               bool &IsRecursive, unsigned &StackDepth) {

  IsRecursive = false;

  StackDepth = 0;

  while (LCtx) {

    if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LCtx)) {

      const Decl *DI = SFC->getDecl();

      // Mark recursive (and mutually recursive) functions and always count

      // them when measuring the stack depth.

      if (DI == D) {

        IsRecursive = true;

        ++StackDepth;

        LCtx = LCtx->getParent();

        continue;

      }

      // Do not count the small functions when determining the stack depth.

      AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(DI);

      if (!isSmall(CalleeADC))

        ++StackDepth;

    }

    LCtx = LCtx->getParent();

  }

}

// The GDM component containing the dynamic dispatch bifurcation info. When

// the exact type of the receiver is not known, we want to explore both paths -

// one on which we do inline it and the other one on which we don't. This is

// done to ensure we do not drop coverage.

// This is the map from the receiver region to a bool, specifying either we

// consider this region's information precise or not along the given path.

namespace {

  enum DynamicDispatchMode {

    DynamicDispatchModeInlined = 1,

    DynamicDispatchModeConservative

  };

} // end anonymous namespace

REGISTER_MAP_WITH_PROGRAMSTATE(DynamicDispatchBifurcationMap,

                               const MemRegion *, unsigned)

bool ExprEngine::inlineCall(const CallEvent &Call, const Decl *D,

                            NodeBuilder &Bldr, ExplodedNode *Pred,

                            ProgramStateRef State) {

  assert(D);

  const LocationContext *CurLC = Pred->getLocationContext();

  const StackFrameContext *CallerSFC = CurLC->getStackFrame();

  const LocationContext *ParentOfCallee = CallerSFC;

  if (Call.getKind() == CE_Block &&

      !cast<BlockCall>(Call).isConversionFromLambda()) {

    const BlockDataRegion *BR = cast<BlockCall>(Call).getBlockRegion();

    assert(BR && "If we have the block definition we should have its region");

    AnalysisDeclContext *BlockCtx = AMgr.getAnalysisDeclContext(D);

    ParentOfCallee = BlockCtx->getBlockInvocationContext(CallerSFC,

                                                         cast<BlockDecl>(D),

                                                         BR);

  }

  // This may be NULL, but that's fine.

  const Expr *CallE = Call.getOriginExpr();

  // Construct a new stack frame for the callee.

  AnalysisDeclContext *CalleeADC = AMgr.getAnalysisDeclContext(D);

  const StackFrameContext *CalleeSFC =

      CalleeADC->getStackFrame(ParentOfCallee, CallE, currBldrCtx->getBlock(),

                               currBldrCtx->blockCount(), currStmtIdx);

  CallEnter Loc(CallE, CalleeSFC, CurLC);

  // Construct a new state which contains the mapping from actual to

  // formal arguments.

  State = State->enterStackFrame(Call, CalleeSFC);

  bool isNew;

  if (ExplodedNode *N = G.getNode(Loc, State, false, &isNew)) {

    N->addPredecessor(Pred, G);

    if (isNew)

      Engine.getWorkList()->enqueue(N);

  }

  // If we decided to inline the call, the successor has been manually

  // added onto the work list so remove it from the node builder.

  Bldr.takeNodes(Pred);

  NumInlinedCalls++;

  Engine.FunctionSummaries->bumpNumTimesInlined(D);

  // Mark the decl as visited.

  if (VisitedCallees)

    VisitedCallees->insert(D);

  return true;

}

static ProgramStateRef getInlineFailedState(ProgramStateRef State,

                                            const Stmt *CallE) {

  const void *ReplayState = State->get<ReplayWithoutInlining>();

  if (!ReplayState)

    return nullptr;

  assert(ReplayState == CallE && "Backtracked to the wrong call.");

  (void)CallE;

  return State->remove<ReplayWithoutInlining>();

}

void ExprEngine::VisitCallExpr(const CallExpr *CE, ExplodedNode *Pred,

                               ExplodedNodeSet &dst) {

  // Perform the previsit of the CallExpr.

  ExplodedNodeSet dstPreVisit;

  getCheckerManager().runCheckersForPreStmt(dstPreVisit, Pred, CE, *this);

  // Get the call in its initial state. We use this as a template to perform

  // all the checks.

  CallEventManager &CEMgr = getStateManager().getCallEventManager();

  CallEventRef<> CallTemplate

    = CEMgr.getSimpleCall(CE, Pred->getState(), Pred->getLocationContext());

  // Evaluate the function call.  We try each of the checkers

  // to see if the can evaluate the function call.

  ExplodedNodeSet dstCallEvaluated;

  for (ExplodedNodeSet::iterator I = dstPreVisit.begin(), E = dstPreVisit.end();

       I != E; 
++I69.1k
) {

    evalCall(dstCallEvaluated, *I, *CallTemplate);

  }

  // Finally, perform the post-condition check of the CallExpr and store

  // the created nodes in 'Dst'.

  // Note that if the call was inlined, dstCallEvaluated will be empty.

  // The post-CallExpr check will occur in processCallExit.

  getCheckerManager().runCheckersForPostStmt(dst, dstCallEvaluated, CE,

                                             *this);

}

ProgramStateRef ExprEngine::finishArgumentConstruction(ProgramStateRef State,

                                                       const CallEvent &Call) {

  const Expr *E = Call.getOriginExpr();

  // FIXME: Constructors to placement arguments of operator new

  // are not supported yet.

  if (!E || 
isa<CXXNewExpr>(E)102k
)

    return State;

  const LocationContext *LC = Call.getLocationContext();

  for (unsigned CallI = 0, CallN = Call.getNumArgs(); CallI != CallN; 
++CallI88.9k
) {

    unsigned I = Call.getASTArgumentIndex(CallI);

    if (Optional<SVal> V =

            getObjectUnderConstruction(State, {E, I}, LC)) {

      SVal VV = *V;

      (void)VV;

      assert(cast<VarRegion>(VV.castAs<loc::MemRegionVal>().getRegion())

                 ->getStackFrame()->getParent()

                 ->getStackFrame() == LC->getStackFrame());

      State = finishObjectConstruction(State, {E, I}, LC);

    }

  }

  return State;

}

void ExprEngine::finishArgumentConstruction(ExplodedNodeSet &Dst,

                                            ExplodedNode *Pred,

                                            const CallEvent &Call) {

  ProgramStateRef State = Pred->getState();

  ProgramStateRef CleanedState = finishArgumentConstruction(State, Call);

  if (CleanedState == State) {

    Dst.insert(Pred);

    return;

  }

  const Expr *E = Call.getOriginExpr();

  const LocationContext *LC = Call.getLocationContext();

  NodeBuilder B(Pred, Dst, *currBldrCtx);

  static SimpleProgramPointTag Tag("ExprEngine",

                                   "Finish argument construction");

  PreStmt PP(E, LC, &Tag);

  B.generateNode(PP, CleanedState, Pred);

}

void ExprEngine::evalCall(ExplodedNodeSet &Dst, ExplodedNode *Pred,

                          const CallEvent &Call) {

  // WARNING: At this time, the state attached to 'Call' may be older than the

  // state in 'Pred'. This is a minor optimization since CheckerManager will

  // use an updated CallEvent instance when calling checkers, but if 'Call' is

  // ever used directly in this function all callers should be updated to pass

  // the most recent state. (It is probably not worth doing the work here since

  // for some callers this will not be necessary.)

  // Run any pre-call checks using the generic call interface.

  ExplodedNodeSet dstPreVisit;

  getCheckerManager().runCheckersForPreCall(dstPreVisit, Pred,

                                            Call, *this);

  // Actually evaluate the function call.  We try each of the checkers

  // to see if the can evaluate the function call, and get a callback at

  // defaultEvalCall if all of them fail.

  ExplodedNodeSet dstCallEvaluated;

  getCheckerManager().runCheckersForEvalCall(dstCallEvaluated, dstPreVisit,

                                             Call, *this, EvalCallOptions());

  // If there were other constructors called for object-type arguments

  // of this call, clean them up.

  ExplodedNodeSet dstArgumentCleanup;

  for (ExplodedNode *I : dstCallEvaluated)

    finishArgumentConstruction(dstArgumentCleanup, I, Call);

  ExplodedNodeSet dstPostCall;

  getCheckerManager().runCheckersForPostCall(dstPostCall, dstArgumentCleanup,

                                             Call, *this);

  // Escaping symbols conjured during invalidating the regions above.

  // Note that, for inlined calls the nodes were put back into the worklist,

  // so we can assume that every node belongs to a conservative call at this

  // point.

  // Run pointerEscape callback with the newly conjured symbols.

  SmallVector<std::pair<SVal, SVal>, 8> Escaped;

  for (ExplodedNode *I : dstPostCall) {

    NodeBuilder B(I, Dst, *currBldrCtx);

    ProgramStateRef State = I->getState();

    Escaped.clear();

    {

      unsigned Arg = -1;

      for (const ParmVarDecl *PVD : Call.parameters()) {

        ++Arg;

        QualType ParamTy = PVD->getType();

        if (ParamTy.isNull() ||

            (!ParamTy->isPointerType() && 
!ParamTy->isReferenceType()32.7k
))

          continue;

        QualType Pointee = ParamTy->getPointeeType();

        if (Pointee.isConstQualified() || 
Pointee->isVoidType()5.76k
)

          continue;

        if (const MemRegion *MR = Call.getArgSVal(Arg).getAsRegion())

          Escaped.emplace_back(loc::MemRegionVal(MR), State->getSVal(MR, Pointee));

      }

    }

    State = processPointerEscapedOnBind(State, Escaped, I->getLocationContext(),

                                        PSK_EscapeOutParameters, &Call);

    if (State == I->getState())

      Dst.insert(I);

    else

      B.generateNode(I->getLocation(), State, I);

  }

}

ProgramStateRef ExprEngine::bindReturnValue(const CallEvent &Call,

                                            const LocationContext *LCtx,

                                            ProgramStateRef State) {

  const Expr *E = Call.getOriginExpr();

  if (!E)

    return State;

  // Some method families have known return values.

  if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(&Call)) {

    switch (Msg->getMethodFamily()) {

    default:

      break;

    case OMF_autorelease:

    case OMF_retain:

    case OMF_self: {

      // These methods return their receivers.

      return State->BindExpr(E, LCtx, Msg->getReceiverSVal());

    }

    }

  } else if (const CXXConstructorCall *C = dyn_cast<CXXConstructorCall>(&Call)){

    SVal ThisV = C->getCXXThisVal();

    ThisV = State->getSVal(ThisV.castAs<Loc>());

    return State->BindExpr(E, LCtx, ThisV);

  }

  SVal R;

  QualType ResultTy = Call.getResultType();

  unsigned Count = currBldrCtx->blockCount();

  if (auto RTC = getCurrentCFGElement().getAs<CFGCXXRecordTypedCall>()) {

    // Conjure a temporary if the function returns an object by value.

    SVal Target;

    assert(RTC->getStmt() == Call.getOriginExpr());

    EvalCallOptions CallOpts; // FIXME: We won't really need those.

    std::tie(State, Target) =

        handleConstructionContext(Call.getOriginExpr(), State, LCtx,

                                  RTC->getConstructionContext(), CallOpts);

    const MemRegion *TargetR = Target.getAsRegion();

    assert(TargetR);

    // Invalidate the region so that it didn't look uninitialized. If this is

    // a field or element constructor, we do not want to invalidate

    // the whole structure. Pointer escape is meaningless because

    // the structure is a product of conservative evaluation

    // and therefore contains nothing interesting at this point.

    RegionAndSymbolInvalidationTraits ITraits;

    ITraits.setTrait(TargetR,

        RegionAndSymbolInvalidationTraits::TK_DoNotInvalidateSuperRegion);

    State = State->invalidateRegions(TargetR, E, Count, LCtx,

                                     /* CausesPointerEscape=*/false, nullptr,

                                     &Call, &ITraits);

    R = State->getSVal(Target.castAs<Loc>(), E->getType());

  } else {

    // Conjure a symbol if the return value is unknown.

    // See if we need to conjure a heap pointer instead of

    // a regular unknown pointer.

    bool IsHeapPointer = false;

    if (const auto *CNE = dyn_cast<CXXNewExpr>(E))

      if (CNE->getOperatorNew()->isReplaceableGlobalAllocationFunction()) {

        // FIXME: Delegate this to evalCall in MallocChecker?

        IsHeapPointer = true;

      }

    R = IsHeapPointer ? 
svalBuilder.getConjuredHeapSymbolVal(E, LCtx, Count)604

                      : svalBuilder.conjureSymbolVal(nullptr, E, LCtx, ResultTy,

                                                     Count);

  }

  return State->BindExpr(E, LCtx, R);

}

// Conservatively evaluate call by invalidating regions and binding

// a conjured return value.

void ExprEngine::conservativeEvalCall(const CallEvent &Call, NodeBuilder &Bldr,

                                      ExplodedNode *Pred, ProgramStateRef State) {

  State = Call.invalidateRegions(currBldrCtx->blockCount(), State);

  State = bindReturnValue(Call, Pred->getLocationContext(), State);

  // And make the result node.

  Bldr.generateNode(Call.getProgramPoint(), State, Pred);

}

ExprEngine::CallInlinePolicy

ExprEngine::mayInlineCallKind(const CallEvent &Call, const ExplodedNode *Pred,

                              AnalyzerOptions &Opts,

                              const EvalCallOptions &CallOpts) {

  const LocationContext *CurLC = Pred->getLocationContext();

  const StackFrameContext *CallerSFC = CurLC->getStackFrame();

  switch (Call.getKind()) {

  case CE_Function:

  case CE_Block:

    break;

  case CE_CXXMember:

  case CE_CXXMemberOperator:

    if (!Opts.mayInlineCXXMemberFunction(CIMK_MemberFunctions))

      return CIP_DisallowedAlways;

    break;

  case CE_CXXConstructor: {

    if (!Opts.mayInlineCXXMemberFunction(CIMK_Constructors))

      return CIP_DisallowedAlways;

    const CXXConstructorCall &Ctor = cast<CXXConstructorCall>(Call);

    const CXXConstructExpr *CtorExpr = Ctor.getOriginExpr();

    auto CCE = getCurrentCFGElement().getAs<CFGConstructor>();

    const ConstructionContext *CC = CCE ? 
CCE->getConstructionContext()8.77k

                                        : nullptr;

    if (llvm::isa_and_nonnull<NewAllocatedObjectConstructionContext>(CC) &&

        !Opts.MayInlineCXXAllocator)

      return CIP_DisallowedOnce;

    // FIXME: We don't handle constructors or destructors for arrays properly.

    // Even once we do, we still need to be careful about implicitly-generated

    // initializers for array fields in default move/copy constructors.

    // We still allow construction into ElementRegion targets when they don't

    // represent array elements.

    if (CallOpts.IsArrayCtorOrDtor)

      return CIP_DisallowedOnce;

    // Inlining constructors requires including initializers in the CFG.

    const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext();

    assert(ADC->getCFGBuildOptions().AddInitializers && "No CFG initializers");

    (void)ADC;

    // If the destructor is trivial, it's always safe to inline the constructor.

    if (Ctor.getDecl()->getParent()->hasTrivialDestructor())

      break;

    // For other types, only inline constructors if destructor inlining is

    // also enabled.

    if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors))

      return CIP_DisallowedAlways;

    if (CtorExpr->getConstructionKind() == CXXConstructExpr::CK_Complete) {

      // If we don't handle temporary destructors, we shouldn't inline

      // their constructors.

      if (CallOpts.IsTemporaryCtorOrDtor &&

          !Opts.ShouldIncludeTemporaryDtorsInCFG)

        return CIP_DisallowedOnce;

      // If we did not find the correct this-region, it would be pointless

      // to inline the constructor. Instead we will simply invalidate

      // the fake temporary target.

      if (CallOpts.IsCtorOrDtorWithImproperlyModeledTargetRegion)

        return CIP_DisallowedOnce;

      // If the temporary is lifetime-extended by binding it to a reference-type

      // field within an aggregate, automatic destructors don't work properly.

      if (CallOpts.IsTemporaryLifetimeExtendedViaAggregate)

        return CIP_DisallowedOnce;

    }

    break;

  }

  case CE_CXXInheritedConstructor: {

    // This doesn't really increase the cost of inlining ever, because

    // the stack frame of the inherited constructor is trivial.

    return CIP_Allowed;

  }

  case CE_CXXDestructor: {

    if (!Opts.mayInlineCXXMemberFunction(CIMK_Destructors))

      return CIP_DisallowedAlways;

    // Inlining destructors requires building the CFG correctly.

    const AnalysisDeclContext *ADC = CallerSFC->getAnalysisDeclContext();

    assert(ADC->getCFGBuildOptions().AddImplicitDtors && "No CFG destructors");

    (void)ADC;

    // FIXME: We don't handle constructors or destructors for arrays properly.

    if (CallOpts.IsArrayCtorOrDtor)

      return CIP_DisallowedOnce;

    // Allow disabling temporary destructor inlining with a separate option.

    if (CallOpts.IsTemporaryCtorOrDtor &&

        !Opts.MayInlineCXXTemporaryDtors)

      return CIP_DisallowedOnce;

    // If we did not find the correct this-region, it would be pointless

    // to inline the destructor. Instead we will simply invalidate

    // the fake temporary target.

    if (CallOpts.IsCtorOrDtorWithImproperlyModeledTargetRegion)

      return CIP_DisallowedOnce;

    break;

  }

  case CE_CXXDeallocator:

    LLVM_FALLTHROUGH;

  case CE_CXXAllocator:

    if (Opts.MayInlineCXXAllocator)

      break;

    // Do not inline allocators until we model deallocators.

    // This is unfortunate, but basically necessary for smart pointers and such.

    return CIP_DisallowedAlways;

  case CE_ObjCMessage:

    if (!Opts.MayInlineObjCMethod)

      return CIP_DisallowedAlways;

    if (!(Opts.getIPAMode() == IPAK_DynamicDispatch ||

          Opts.getIPAMode() == IPAK_DynamicDispatchBifurcate))

      return CIP_DisallowedAlways;

    break;

  }

  return CIP_Allowed;

}

/// Returns true if the given C++ class contains a member with the given name.

static bool hasMember(const ASTContext &Ctx, const CXXRecordDecl *RD,

                      StringRef Name) {

  const IdentifierInfo &II = Ctx.Idents.get(Name);

  return RD->hasMemberName(Ctx.DeclarationNames.getIdentifier(&II));

}

/// Returns true if the given C++ class is a container or iterator.

///

/// Our heuristic for this is whether it contains a method named 'begin()' or a

/// nested type named 'iterator' or 'iterator_category'.

static bool isContainerClass(const ASTContext &Ctx, const CXXRecordDecl *RD) {

  return hasMember(Ctx, RD, "begin") ||

         hasMember(Ctx, RD, "iterator") ||

         hasMember(Ctx, RD, "iterator_category");

}

/// Returns true if the given function refers to a method of a C++ container

/// or iterator.

///

/// We generally do a poor job modeling most containers right now, and might

/// prefer not to inline their methods.

static bool isContainerMethod(const ASTContext &Ctx,

                              const FunctionDecl *FD) {

  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))

    return isContainerClass(Ctx, MD->getParent());

  return false;

}

/// Returns true if the given function is the destructor of a class named

/// "shared_ptr".

static bool isCXXSharedPtrDtor(const FunctionDecl *FD) {

  const CXXDestructorDecl *Dtor = dyn_cast<CXXDestructorDecl>(FD);

  if (!Dtor)

    return false;

  const CXXRecordDecl *RD = Dtor->getParent();

  if (const IdentifierInfo *II = RD->getDeclName().getAsIdentifierInfo())

    if (II->isStr("shared_ptr"))

        return true;

  return false;

}

/// Returns true if the function in \p CalleeADC may be inlined in general.

///

/// This checks static properties of the function, such as its signature and

/// CFG, to determine whether the analyzer should ever consider inlining it,

/// in any context.

bool ExprEngine::mayInlineDecl(AnalysisDeclContext *CalleeADC) const {

  AnalyzerOptions &Opts = AMgr.getAnalyzerOptions();

  // FIXME: Do not inline variadic calls.

  if (CallEvent::isVariadic(CalleeADC->getDecl()))

    return false;

  // Check certain C++-related inlining policies.

  ASTContext &Ctx = CalleeADC->getASTContext();

  if (Ctx.getLangOpts().CPlusPlus) {

    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CalleeADC->getDecl())) {

      // Conditionally control the inlining of template functions.

      if (!Opts.MayInlineTemplateFunctions)

        if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate)

          return false;

      // Conditionally control the inlining of C++ standard library functions.

      if (!Opts.MayInlineCXXStandardLibrary)

        if (Ctx.getSourceManager().isInSystemHeader(FD->getLocation()))

          if (AnalysisDeclContext::isInStdNamespace(FD))

            return false;

      // Conditionally control the inlining of methods on objects that look

      // like C++ containers.

      if (!Opts.MayInlineCXXContainerMethods)

        if (!AMgr.isInCodeFile(FD->getLocation()))

          if (isContainerMethod(Ctx, FD))

            return false;

      // Conditionally control the inlining of the destructor of C++ shared_ptr.

      // We don't currently do a good job modeling shared_ptr because we can't

      // see the reference count, so treating as opaque is probably the best

      // idea.

      if (!Opts.MayInlineCXXSharedPtrDtor)

        if (isCXXSharedPtrDtor(FD))

          return false;

    }

  }

  // It is possible that the CFG cannot be constructed.

  // Be safe, and check if the CalleeCFG is valid.

  const CFG *CalleeCFG = CalleeADC->getCFG();

  if (!CalleeCFG)

    return false;

  // Do not inline large functions.

  if (isHuge(CalleeADC))

    return false;

  // It is possible that the live variables analysis cannot be

  // run.  If so, bail out.

  if (!CalleeADC->getAnalysis<RelaxedLiveVariables>())

    return false;

  return true;

}

bool ExprEngine::shouldInlineCall(const CallEvent &Call, const Decl *D,

                                  const ExplodedNode *Pred,

                                  const EvalCallOptions &CallOpts) {

  if (!D)

    return false;

  AnalysisManager &AMgr = getAnalysisManager();

  AnalyzerOptions &Opts = AMgr.options;

  AnalysisDeclContextManager &ADCMgr = AMgr.getAnalysisDeclContextManager();

  AnalysisDeclContext *CalleeADC = ADCMgr.getContext(D);

  // The auto-synthesized bodies are essential to inline as they are

  // usually small and commonly used. Note: we should do this check early on to

  // ensure we always inline these calls.

  if (CalleeADC->isBodyAutosynthesized())

    return true;

  if (!AMgr.shouldInlineCall())

    return false;

  // Check if this function has been marked as non-inlinable.

  Optional<bool> MayInline = Engine.FunctionSummaries->mayInline(D);

  if (MayInline.hasValue()) {

    if (!MayInline.getValue())

      return false;

  } else {

    // We haven't actually checked the static properties of this function yet.

    // Do that now, and record our decision in the function summaries.

    if (mayInlineDecl(CalleeADC)) {

      Engine.FunctionSummaries->markMayInline(D);

    } else {

      Engine.FunctionSummaries->markShouldNotInline(D);

      return false;

    }

  }

  // Check if we should inline a call based on its kind.

  // FIXME: this checks both static and dynamic properties of the call, which

  // means we're redoing a bit of work that could be cached in the function

  // summary.

  CallInlinePolicy CIP = mayInlineCallKind(Call, Pred, Opts, CallOpts);

  if (CIP != CIP_Allowed) {

    if (CIP == CIP_DisallowedAlways) {

      assert(!MayInline.hasValue() || MayInline.getValue());

      Engine.FunctionSummaries->markShouldNotInline(D);

    }

    return false;

  }

  // Do not inline if recursive or we've reached max stack frame count.

  bool IsRecursive = false;

  unsigned StackDepth = 0;

  examineStackFrames(D, Pred->getLocationContext(), IsRecursive, StackDepth);

  if ((StackDepth >= Opts.InlineMaxStackDepth) &&

      (!isSmall(CalleeADC) || 
IsRecursive275
))

    return false;

  // Do not inline large functions too many times.

  if ((Engine.FunctionSummaries->getNumTimesInlined(D) >

       Opts.MaxTimesInlineLarge) &&

      isLarge(CalleeADC)) {

    NumReachedInlineCountMax++;

    return false;

  }

  if (HowToInline == Inline_Minimal && 
(25
!isSmall(CalleeADC)25
 || 
IsRecursive24
))

    return false;

  return true;

}

static bool isTrivialObjectAssignment(const CallEvent &Call) {

  const CXXInstanceCall *ICall = dyn_cast<CXXInstanceCall>(&Call);

  if (!ICall)

    return false;

  const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(ICall->getDecl());

  if (!MD)

    return false;

  if (!(MD->isCopyAssignmentOperator() || 
MD->isMoveAssignmentOperator()12.8k
))

    return false;

  return MD->isTrivial();

}

void ExprEngine::defaultEvalCall(NodeBuilder &Bldr, ExplodedNode *Pred,

                                 const CallEvent &CallTemplate,

                                 const EvalCallOptions &CallOpts) {

  // Make sure we have the most recent state attached to the call.

  ProgramStateRef State = Pred->getState();

  CallEventRef<> Call = CallTemplate.cloneWithState(State);

  // Special-case trivial assignment operators.

  if (isTrivialObjectAssignment(*Call)) {

    performTrivialCopy(Bldr, Pred, *Call);

    return;

  }