C++ ExprEngine::getContext方法代码示例

bool OSAtomicChecker::evalOSAtomicCompareAndSwap(const CallExpr *CE,
                                                 ExprEngine &Eng,
                                                 ExplodedNode *Pred,
                                                 ExplodedNodeSet &Dst) const {
  // Not enough arguments to match OSAtomicCompareAndSwap?
  if (CE->getNumArgs() != 3)
    return false;

  ASTContext &Ctx = Eng.getContext();
  const Expr *oldValueExpr = CE->getArg(0);
  QualType oldValueType = Ctx.getCanonicalType(oldValueExpr->getType());

  const Expr *newValueExpr = CE->getArg(1);
  QualType newValueType = Ctx.getCanonicalType(newValueExpr->getType());

  // Do the types of 'oldValue' and 'newValue' match?
  if (oldValueType != newValueType)
    return false;

  const Expr *theValueExpr = CE->getArg(2);
  const PointerType *theValueType=theValueExpr->getType()->getAs<PointerType>();

  // theValueType not a pointer?
  if (!theValueType)
    return false;

  QualType theValueTypePointee =
    Ctx.getCanonicalType(theValueType->getPointeeType()).getUnqualifiedType();

  // The pointee must match newValueType and oldValueType.
  if (theValueTypePointee != newValueType)
    return false;

  static SimpleProgramPointTag OSAtomicLoadTag("OSAtomicChecker : Load");
  static SimpleProgramPointTag OSAtomicStoreTag("OSAtomicChecker : Store");
  
  // Load 'theValue'.
  ProgramStateRef state = Pred->getState();
  const LocationContext *LCtx = Pred->getLocationContext();
  ExplodedNodeSet Tmp;
  SVal location = state->getSVal(theValueExpr, LCtx);
  // Here we should use the value type of the region as the load type, because
  // we are simulating the semantics of the function, not the semantics of 
  // passing argument. So the type of theValue expr is not we are loading.
  // But usually the type of the varregion is not the type we want either,
  // we still need to do a CastRetrievedVal in store manager. So actually this
  // LoadTy specifying can be omitted. But we put it here to emphasize the 
  // semantics.
  QualType LoadTy;
  if (const TypedValueRegion *TR =
      dyn_cast_or_null<TypedValueRegion>(location.getAsRegion())) {
    LoadTy = TR->getValueType();
  }
  Eng.evalLoad(Tmp, CE, theValueExpr, Pred,
               state, location, &OSAtomicLoadTag, LoadTy);

  if (Tmp.empty()) {
    // If no nodes were generated, other checkers must have generated sinks. 
    // We return an empty Dst.
    return true;
  }
 
  for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end();
       I != E; ++I) {

    ExplodedNode *N = *I;
    ProgramStateRef stateLoad = N->getState();

    // Use direct bindings from the environment since we are forcing a load
    // from a location that the Environment would typically not be used
    // to bind a value.
    SVal theValueVal_untested = stateLoad->getSVal(theValueExpr, LCtx, true);

    SVal oldValueVal_untested = stateLoad->getSVal(oldValueExpr, LCtx);

    // FIXME: Issue an error.
    if (theValueVal_untested.isUndef() || oldValueVal_untested.isUndef()) {
      return false;
    }
    
    DefinedOrUnknownSVal theValueVal =
      cast<DefinedOrUnknownSVal>(theValueVal_untested);
    DefinedOrUnknownSVal oldValueVal =
      cast<DefinedOrUnknownSVal>(oldValueVal_untested);

    SValBuilder &svalBuilder = Eng.getSValBuilder();

    // Perform the comparison.
    DefinedOrUnknownSVal Cmp =
      svalBuilder.evalEQ(stateLoad,theValueVal,oldValueVal);

    ProgramStateRef stateEqual = stateLoad->assume(Cmp, true);

    // Were they equal?
    if (stateEqual) {
      // Perform the store.
      ExplodedNodeSet TmpStore;
      SVal val = stateEqual->getSVal(newValueExpr, LCtx);

      // Handle implicit value casts.
//.........这里部分代码省略.........

void UnreachableCodeChecker::checkEndAnalysis(ExplodedGraph &G,
                                              BugReporter &B,
                                              ExprEngine &Eng) const {
  CFGBlocksSet reachable, visited;

  if (Eng.hasWorkRemaining())
    return;

  const Decl *D = nullptr;
  CFG *C = nullptr;
  ParentMap *PM = nullptr;
  const LocationContext *LC = nullptr;
  // Iterate over ExplodedGraph
  for (ExplodedGraph::node_iterator I = G.nodes_begin(), E = G.nodes_end();
      I != E; ++I) {
    const ProgramPoint &P = I->getLocation();
    LC = P.getLocationContext();
    if (!LC->inTopFrame())
      continue;

    if (!D)
      D = LC->getAnalysisDeclContext()->getDecl();

    // Save the CFG if we don't have it already
    if (!C)
      C = LC->getAnalysisDeclContext()->getUnoptimizedCFG();
    if (!PM)
      PM = &LC->getParentMap();

    if (Optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
      const CFGBlock *CB = BE->getBlock();
      reachable.insert(CB->getBlockID());
    }
  }

  // Bail out if we didn't get the CFG or the ParentMap.
  if (!D || !C || !PM)
    return;

  // Don't do anything for template instantiations.  Proving that code
  // in a template instantiation is unreachable means proving that it is
  // unreachable in all instantiations.
  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
    if (FD->isTemplateInstantiation())
      return;

  // Find CFGBlocks that were not covered by any node
  for (CFG::const_iterator I = C->begin(), E = C->end(); I != E; ++I) {
    const CFGBlock *CB = *I;
    // Check if the block is unreachable
    if (reachable.count(CB->getBlockID()))
      continue;

    // Check if the block is empty (an artificial block)
    if (isEmptyCFGBlock(CB))
      continue;

    // Find the entry points for this block
    if (!visited.count(CB->getBlockID()))
      FindUnreachableEntryPoints(CB, reachable, visited);

    // This block may have been pruned; check if we still want to report it
    if (reachable.count(CB->getBlockID()))
      continue;

    // Check for false positives
    if (isInvalidPath(CB, *PM))
      continue;

    // It is good practice to always have a "default" label in a "switch", even
    // if we should never get there. It can be used to detect errors, for
    // instance. Unreachable code directly under a "default" label is therefore
    // likely to be a false positive.
    if (const Stmt *label = CB->getLabel())
      if (label->getStmtClass() == Stmt::DefaultStmtClass)
        continue;

    // Special case for __builtin_unreachable.
    // FIXME: This should be extended to include other unreachable markers,
    // such as llvm_unreachable.
    if (!CB->empty()) {
      bool foundUnreachable = false;
      for (CFGBlock::const_iterator ci = CB->begin(), ce = CB->end();
           ci != ce; ++ci) {
        if (Optional<CFGStmt> S = (*ci).getAs<CFGStmt>())
          if (const CallExpr *CE = dyn_cast<CallExpr>(S->getStmt())) {
            if (CE->getBuiltinCallee() == Builtin::BI__builtin_unreachable ||
                CE->isBuiltinAssumeFalse(Eng.getContext())) {
              foundUnreachable = true;
              break;
            }
          }
      }
      if (foundUnreachable)
        continue;
    }

    // We found a block that wasn't covered - find the statement to report
    SourceRange SR;
    PathDiagnosticLocation DL;
//.........这里部分代码省略.........

void ento::RegisterObjCAtSyncChecker(ExprEngine &Eng) {
  // @synchronized is an Objective-C 2 feature.
  if (Eng.getContext().getLangOptions().ObjC2)
    Eng.registerCheck(new ObjCAtSyncChecker());
}