[analyzer] [NFC] Factor out generating path diagnostics for a statement into a function

[george.karpenkov]

Summary

Phabricator diff fails to detect the move, so probably easier to look at two files side-by-side.

[NoQ]

Is the new function usable for other diagnostic generators? Or should we call it generateMinimalDiagnosticsForStmt()?

[george.karpenkov]

@NoQ a good point, extended refactoring across all diagnostics types.

[NoQ]

Yeah, that's a lot less loops to worry about.

cfe/trunk/lib/StaticAnalyzer/Core/BugReporter.cpp

if (ep->hasCallStackHint())
         if  (!CP->hasCallStackMessage())
           CP->setCallStackMessage(stackMsg);
       }
   }
 }
 
 static void CompactPathDiagnostic(PathPieces &path, const SourceManager& SM);
 
-static bool GenerateMinimalPathDiagnostic(
-    PathDiagnostic &PD, PathDiagnosticBuilder &PDB, const ExplodedNode *N,
-    LocationContextMap &LCM,
-    ArrayRef<std::unique_ptr<BugReporterVisitor>> visitors) {
-
-  SourceManager& SMgr = PDB.getSourceManager();
-  const LocationContext *LC = PDB.LC;
-  const ExplodedNode *NextNode = N->pred_empty()
-                                        ? nullptr : *(N->pred_begin());
-
-  StackDiagVector CallStack;
-
-  while (NextNode) {
-    N = NextNode;
-    PDB.LC = N->getLocationContext();
-    NextNode = N->getFirstPred();
-
-    ProgramPoint P = N->getLocation();
-
-    do {
-      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
-        auto C = PathDiagnosticCallPiece::construct(N, *CE, SMgr);
-        // Record the mapping from call piece to LocationContext.
-        LCM[&C->path] = CE->getCalleeContext();
-        auto *P = C.get();
-        PD.getActivePath().push_front(std::move(C));
-        PD.pushActivePath(&P->path);
-        CallStack.push_back(StackDiagPair(P, N));
-        break;
-      }
-
-      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
-        // Flush all locations, and pop the active path.
-        bool VisitedEntireCall = PD.isWithinCall();
-        PD.popActivePath();
 
-        // Either we just added a bunch of stuff to the top-level path, or
-        // we have a previous CallExitEnd.  If the former, it means that the
-        // path terminated within a function call.  We must then take the
-        // current contents of the active path and place it within
-        // a new PathDiagnosticCallPiece.
-        PathDiagnosticCallPiece *C;
-        if (VisitedEntireCall) {
-          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front().get());
-        } else {
-          const Decl *Caller = CE->getLocationContext()->getDecl();
-          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
-          // Record the mapping from call piece to LocationContext.
-          LCM[&C->path] = CE->getCalleeContext();
-        }
+/// Add path diagnostic for statement associated with node \p N
+/// to diagnostics \p PD.
+/// Precondition: location associated with \p N is a \c BlockEdge.
+static void generateMinimalDiagnosticsForBlockEdge(const ExplodedNode *N,
+                                       PathDiagnosticBuilder &PDB,
+                                       PathDiagnostic &PD) {
 
-        C->setCallee(*CE, SMgr);
-        if (!CallStack.empty()) {
-          assert(CallStack.back().first == C);
-          CallStack.pop_back();
-        }
-        break;
-      }
-
-      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
-        const CFGBlock *Src = BE->getSrc();
-        const CFGBlock *Dst = BE->getDst();
-        const Stmt *T = Src->getTerminator();
-
-        if (!T)
-          break;
-
-        PathDiagnosticLocation Start =
-            PathDiagnosticLocation::createBegin(T, SMgr,
-                N->getLocationContext());
+  const LocationContext *LC = N->getLocationContext();
+  SourceManager& SMgr = PDB.getSourceManager();
+  BlockEdge BE = N->getLocation().castAs<BlockEdge>();
+  const CFGBlock *Src = BE.getSrc();
+  const CFGBlock *Dst = BE.getDst();
+    return;
 
-        switch (T->getStmtClass()) {
-        default:
-          break;
+  auto Start = PathDiagnosticLocation::createBegin(T, SMgr, LC);
 
-        case Stmt::GotoStmtClass:
-        case Stmt::IndirectGotoStmtClass: {
-          const Stmt *S = PathDiagnosticLocation::getNextStmt(N);
 
-          if (!S)
-            break;
 
-          std::string sbuf;
-          llvm::raw_string_ostream os(sbuf);
-          const PathDiagnosticLocation &End = PDB.getEnclosingStmtLocation(S);
 
-          os << "Control jumps to line "
-              << End.asLocation().getExpansionLineNumber();
-          PD.getActivePath().push_front(
-              std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                               os.str()));
-          break;
-        }
+    os << "Control jumps to line " << End.asLocation().getExpansionLineNumber();
+        std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, os.str()));
 
-        case Stmt::SwitchStmtClass: {
-          // Figure out what case arm we took.
-          std::string sbuf;
-          llvm::raw_string_ostream os(sbuf);
 
-          if (const Stmt *S = Dst->getLabel()) {
-            PathDiagnosticLocation End(S, SMgr, LC);
 
-            switch (S->getStmtClass()) {
-            default:
-              os << "No cases match in the switch statement. "
               "Control jumps to line "
-              << End.asLocation().getExpansionLineNumber();
-              break;
-            case Stmt::DefaultStmtClass:
-              os << "Control jumps to the 'default' case at line "
-              << End.asLocation().getExpansionLineNumber();
-              break;
 
-            case Stmt::CaseStmtClass: {
-              os << "Control jumps to 'case ";
-              const CaseStmt *Case = cast<CaseStmt>(S);
-              const Expr *LHS = Case->getLHS()->IgnoreParenCasts();
 
-              // Determine if it is an enum.
-              bool GetRawInt = true;
 
-              if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(LHS)) {
-                // FIXME: Maybe this should be an assertion.  Are there cases
-                // were it is not an EnumConstantDecl?
-                const EnumConstantDecl *D =
-                    dyn_cast<EnumConstantDecl>(DR->getDecl());
+          const EnumConstantDecl *D = dyn_cast<EnumConstantDecl>(DR->getDecl());
 
-                if (D) {
-                  GetRawInt = false;
-                  os << *D;
-                }
-              }
 
-              if (GetRawInt)
-                os << LHS->EvaluateKnownConstInt(PDB.getASTContext());
 
-              os << ":'  at line "
-                  << End.asLocation().getExpansionLineNumber();
-              break;
-            }
-            }
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                 os.str()));
-          }
-          else {
-            os << "'Default' branch taken. ";
-            const PathDiagnosticLocation &End = PDB.ExecutionContinues(os, N);
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                 os.str()));
-          }
+        os << ":'  at line " << End.asLocation().getExpansionLineNumber();
+    } else {
 
-          break;
-        }
 
-        case Stmt::BreakStmtClass:
-        case Stmt::ContinueStmtClass: {
-          std::string sbuf;
-          llvm::raw_string_ostream os(sbuf);
-          PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
-          PD.getActivePath().push_front(
-              std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                               os.str()));
-          break;
-        }
+        std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, os.str()));
 
-        // Determine control-flow for ternary '?'.
-        case Stmt::BinaryConditionalOperatorClass:
-        case Stmt::ConditionalOperatorClass: {
-          std::string sbuf;
-          llvm::raw_string_ostream os(sbuf);
-          os << "'?' condition is ";
 
-          if (*(Src->succ_begin()+1) == Dst)
-            os << "false";
-          else
-            os << "true";
+    if (*(Src->succ_begin() + 1) == Dst)
 
-          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
 
-          if (const Stmt *S = End.asStmt())
-            End = PDB.getEnclosingStmtLocation(S);
 
-          PD.getActivePath().push_front(
-              std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                               os.str()));
-          break;
-        }
+        std::make_shared<PathDiagnosticControlFlowPiece>(Start, End, os.str()));
 
-        // Determine control-flow for short-circuited '&&' and '||'.
-        case Stmt::BinaryOperatorClass: {
-          if (!PDB.supportsLogicalOpControlFlow())
-            break;
 
-          const BinaryOperator *B = cast<BinaryOperator>(T);
-          std::string sbuf;
-          llvm::raw_string_ostream os(sbuf);
-          os << "Left side of '";
 
-          if (B->getOpcode() == BO_LAnd) {
-            os << "&&" << "' is ";
+      os << "&&"
+         << "' is ";
 
-            if (*(Src->succ_begin()+1) == Dst) {
-              os << "false";
-              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
-              PathDiagnosticLocation Start =
-                  PathDiagnosticLocation::createOperatorLoc(B, SMgr);
-              PD.getActivePath().push_front(
-                  std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                   os.str()));
-            }
-            else {
-              os << "true";
-              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
-              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
-              PD.getActivePath().push_front(
-                  std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                   os.str()));
-            }
-          }
-          else {
-            assert(B->getOpcode() == BO_LOr);
-            os << "||" << "' is ";
+      if (*(Src->succ_begin() + 1) == Dst) {
+      } else {
+    } else {
+      os << "||"
+         << "' is ";
 
-            if (*(Src->succ_begin()+1) == Dst) {
-              os << "false";
-              PathDiagnosticLocation Start(B->getLHS(), SMgr, LC);
-              PathDiagnosticLocation End = PDB.ExecutionContinues(N);
-              PD.getActivePath().push_front(
-                  std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                   os.str()));
-            }
-            else {
-              os << "true";
-              PathDiagnosticLocation End(B->getLHS(), SMgr, LC);
-              PathDiagnosticLocation Start =
-                  PathDiagnosticLocation::createOperatorLoc(B, SMgr);
-              PD.getActivePath().push_front(
-                  std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                   os.str()));
-            }
-          }
+      if (*(Src->succ_begin() + 1) == Dst) {
+      } else {
 
-          break;
-        }
 
-        case Stmt::DoStmtClass:  {
-          if (*(Src->succ_begin()) == Dst) {
-            std::string sbuf;
-            llvm::raw_string_ostream os(sbuf);
+  case Stmt::DoStmtClass: {
 
-            os << "Loop condition is true. ";
-            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
 
-            if (const Stmt *S = End.asStmt())
-              End = PDB.getEnclosingStmtLocation(S);
 
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                 os.str()));
-          }
-          else {
-            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
+    } else {
 
-            if (const Stmt *S = End.asStmt())
-              End = PDB.getEnclosingStmtLocation(S);
 
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(
-                    Start, End, "Loop condition is false.  Exiting loop"));
-          }
 
-          break;
-        }
 
-        case Stmt::WhileStmtClass:
-        case Stmt::ForStmtClass: {
-          if (*(Src->succ_begin()+1) == Dst) {
-            std::string sbuf;
-            llvm::raw_string_ostream os(sbuf);
+    if (*(Src->succ_begin() + 1) == Dst) {
 
-            os << "Loop condition is false. ";
-            PathDiagnosticLocation End = PDB.ExecutionContinues(os, N);
-            if (const Stmt *S = End.asStmt())
-              End = PDB.getEnclosingStmtLocation(S);
 
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(Start, End,
-                                                                 os.str()));
-          }
-          else {
-            PathDiagnosticLocation End = PDB.ExecutionContinues(N);
-            if (const Stmt *S = End.asStmt())
-              End = PDB.getEnclosingStmtLocation(S);
+    } else {
 
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(
-                    Start, End, "Loop condition is true.  Entering loop body"));
-          }
 
-          break;
-        }
 
-        case Stmt::IfStmtClass: {
-          PathDiagnosticLocation End = PDB.ExecutionContinues(N);
 
-          if (const Stmt *S = End.asStmt())
-            End = PDB.getEnclosingStmtLocation(S);
 
-          if (*(Src->succ_begin()+1) == Dst)
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(
-                    Start, End, "Taking false branch"));
-          else
-            PD.getActivePath().push_front(
-                std::make_shared<PathDiagnosticControlFlowPiece>(
-                    Start, End, "Taking true branch"));
+    if (*(Src->succ_begin() + 1) == Dst)
 
-          break;
-        }
-        }
-      }
-    } while(0);
+
+/// Generate minimal diagnostics for node \p N, and write it into path
+/// diagnostics \p PD.
+void generateMinimalDiagnosticsForNode(const ExplodedNode *N,
+    PathDiagnosticBuilder &PDB,
+    PathDiagnostic &PD,
+    LocationContextMap &LCM,
+    StackDiagVector &CallStack) {
+
+  SourceManager &SMgr = PDB.getSourceManager();
+  ProgramPoint P = N->getLocation();
+
+  if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
+    auto C = PathDiagnosticCallPiece::construct(N, *CE, SMgr);
+    // Record the mapping from call piece to LocationContext.
+    LCM[&C->path] = CE->getCalleeContext();
+    auto *P = C.get();
+    PD.getActivePath().push_front(std::move(C));
+    PD.pushActivePath(&P->path);
+    CallStack.push_back(StackDiagPair(P, N));
+  } else if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
+    // Flush all locations, and pop the active path.
+    bool VisitedEntireCall = PD.isWithinCall();
+    PD.popActivePath();
+
+    // Either we just added a bunch of stuff to the top-level path, or
+    // we have a previous CallExitEnd.  If the former, it means that the
+    // path terminated within a function call.  We must then take the
+    // current contents of the active path and place it within
+    // a new PathDiagnosticCallPiece.
+    PathDiagnosticCallPiece *C;
+    if (VisitedEntireCall) {
+      C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front().get());
+    } else {
+      const Decl *Caller = CE->getLocationContext()->getDecl();
+      C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
+      // Record the mapping from call piece to LocationContext.
+      LCM[&C->path] = CE->getCalleeContext();
+    }
+
+    C->setCallee(*CE, SMgr);
+    if (!CallStack.empty()) {
+      assert(CallStack.back().first == C);
+      CallStack.pop_back();
+    }
+  } else if (P.getKind() == ProgramPoint::BlockEdgeKind) {
+    generateMinimalDiagnosticsForBlockEdge(N, PDB, PD);
+  }
+}
+
+static bool GenerateMinimalPathDiagnostic(
+    PathDiagnostic &PD, PathDiagnosticBuilder &PDB, const ExplodedNode *N,
+    LocationContextMap &LCM,
+    ArrayRef<std::unique_ptr<BugReporterVisitor>> visitors) {
+  const ExplodedNode *NextNode = N->pred_empty()
+                                        ? nullptr : *(N->pred_begin());
+  StackDiagVector CallStack;
+
+  while (NextNode) {
+    N = NextNode;
+    PDB.LC = N->getLocationContext();
+    NextNode = N->getFirstPred();
+
+    generateMinimalDiagnosticsForNode(N, PDB, PD, LCM, CallStack);
 
     if (NextNode) {
       // Add diagnostic pieces from custom visitors.
       BugReport *R = PDB.getBugReport();
       llvm::FoldingSet<PathDiagnosticPiece> DeduplicationSet;
       for (auto &V : visitors) {
         if (auto p = V->VisitNode(N, NextNode, PDB, *R)) {
           if (DeduplicationSet.GetOrInsertNode(p.get()) != p.get())
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CalleeCtx->getDecl())) {
               IE.insert(ArgE);
           }
         }
       }
     }
   }
 }
 
+
+
 //===----------------------------------------------------------------------===//
 // Functions for determining if a loop was executed 0 times.
 //===----------------------------------------------------------------------===//
 
 static bool isLoop(const Stmt *Term) {
   switch (Term->getStmtClass()) {
     case Stmt::ForStmtClass:
     case Stmt::WhileStmtClass:
case Stmt::WhileStmtClass:
       LoopBody = cast<WhileStmt>(Term)->getBody();
       break;
     default:
       return false;
   }
   return isContainedByStmt(PM, LoopBody, S);
 }
 
-//===----------------------------------------------------------------------===//
-// Top-level logic for generating extensive path diagnostics.
-//===----------------------------------------------------------------------===//
-
-static bool GenerateExtensivePathDiagnostic(
-    PathDiagnostic &PD, PathDiagnosticBuilder &PDB, const ExplodedNode *N,
+/// Generate extensive diagnostics for statement associated with node \p N,
+/// and write it into \p PD.
+static void generateExtensiveDiagnosticsForNode(
+        const ExplodedNode *N,
+        PathDiagnosticBuilder &PDB,
         LocationContextMap &LCM,
-    ArrayRef<std::unique_ptr<BugReporterVisitor>> visitors) {
-  EdgeBuilder EB(PD, PDB);
-  const SourceManager& SM = PDB.getSourceManager();
-  StackDiagVector CallStack;
-  InterestingExprs IE;
+        EdgeBuilder &EB,
+        StackDiagVector &CallStack,
+        PathDiagnostic &PD,
+        InterestingExprs &IE) {
 
-  const ExplodedNode *NextNode = N->pred_empty() ? nullptr : *(N->pred_begin());
-  while (NextNode) {
-    N = NextNode;
-    NextNode = N->getFirstPred();
-    ProgramPoint P = N->getLocation();
+  const ExplodedNode *NextNode = N->getFirstPred();
+  const SourceManager& SM = PDB.getSourceManager();
 
-    do {
-      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
-        if (const Expr *Ex = PS->getStmtAs<Expr>())
-          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
-                                              N->getState().get(), Ex,
-                                              N->getLocationContext());
-      }
-
-      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
-        const Stmt *S = CE->getCalleeContext()->getCallSite();
-        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
-            reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
-                                                N->getState().get(), Ex,
-                                                N->getLocationContext());
-        }
+    return;
+  } else if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
 
-        auto C = PathDiagnosticCallPiece::construct(N, *CE, SM);
-        LCM[&C->path] = CE->getCalleeContext();
 
-        EB.addEdge(C->callReturn, /*AlwaysAdd=*/true, /*IsPostJump=*/true);
-        EB.flushLocations();
 
-        auto *P = C.get();
-        PD.getActivePath().push_front(std::move(C));
-        PD.pushActivePath(&P->path);
-        CallStack.push_back(StackDiagPair(P, N));
-        break;
-      }
+    return;
+  } else if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
 
-      // Pop the call hierarchy if we are done walking the contents
-      // of a function call.
-      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
-        // Add an edge to the start of the function.
-        const Decl *D = CE->getCalleeContext()->getDecl();
-        PathDiagnosticLocation pos =
-          PathDiagnosticLocation::createBegin(D, SM);
-        EB.addEdge(pos);
+
 
-        // Flush all locations, and pop the active path.
-        bool VisitedEntireCall = PD.isWithinCall();
-        EB.flushLocations();
-        PD.popActivePath();
-        PDB.LC = N->getLocationContext();
 
-        // Either we just added a bunch of stuff to the top-level path, or
-        // we have a previous CallExitEnd.  If the former, it means that the
-        // path terminated within a function call.  We must then take the
-        // current contents of the active path and place it within
-        // a new PathDiagnosticCallPiece.
-        PathDiagnosticCallPiece *C;
-        if (VisitedEntireCall) {
-          C = cast<PathDiagnosticCallPiece>(PD.getActivePath().front().get());
-        } else {
-          const Decl *Caller = CE->getLocationContext()->getDecl();
-          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
-          LCM[&C->path] = CE->getCalleeContext();
-        }
 
-        C->setCallee(*CE, SM);
-        EB.addContext(C->getLocation());
 
-        if (!CallStack.empty()) {
-          assert(CallStack.back().first == C);
-          CallStack.pop_back();
-        }
-        break;
-      }
+    return;
 
-      // Note that is important that we update the LocationContext
-      // after looking at CallExits.  CallExit basically adds an
-      // edge in the *caller*, so we don't want to update the LocationContext
-      // too soon.
-      PDB.LC = N->getLocationContext();
 
-      // Block edges.
-      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
-        // Does this represent entering a call?  If so, look at propagating
-        // interesting symbols across call boundaries.
-        if (NextNode) {
-          const LocationContext *CallerCtx = NextNode->getLocationContext();
-          const LocationContext *CalleeCtx = PDB.LC;
-          if (CallerCtx != CalleeCtx) {
-            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
-                                               N->getState().get(),
-                                               CalleeCtx, CallerCtx);
-          }
-        }
 
-        // Are we jumping to the head of a loop?  Add a special diagnostic.
-        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
-          PathDiagnosticLocation L(Loop, SM, PDB.LC);
-          const CompoundStmt *CS = nullptr;
 
-          if (const ForStmt *FS = dyn_cast<ForStmt>(Loop))
-            CS = dyn_cast<CompoundStmt>(FS->getBody());
-          else if (const WhileStmt *WS = dyn_cast<WhileStmt>(Loop))
-            CS = dyn_cast<CompoundStmt>(WS->getBody());
 
-          auto p = std::make_shared<PathDiagnosticEventPiece>(
-              L, "Looping back to the head of the loop");
-          p->setPrunable(true);
 
-          EB.addEdge(p->getLocation(), true);
-          PD.getActivePath().push_front(std::move(p));
 
-          if (CS) {
-            PathDiagnosticLocation BL =
-              PathDiagnosticLocation::createEndBrace(CS, SM);
-            EB.addEdge(BL);
-          }
-        }
 
-        const CFGBlock *BSrc = BE->getSrc();
-        ParentMap &PM = PDB.getParentMap();
 
-        if (const Stmt *Term = BSrc->getTerminator()) {
-          // Are we jumping past the loop body without ever executing the
-          // loop (because the condition was false)?
-          if (isLoopJumpPastBody(Term, &*BE) &&
-              !isInLoopBody(PM,
-                            getStmtBeforeCond(PM,
-                                              BSrc->getTerminatorCondition(),
-                                              N),
-                            Term)) {
-            PathDiagnosticLocation L(Term, SM, PDB.LC);
-            auto PE = std::make_shared<PathDiagnosticEventPiece>(
-                L, "Loop body executed 0 times");
-            PE->setPrunable(true);
 
-            EB.addEdge(PE->getLocation(), true);
-            PD.getActivePath().push_front(std::move(PE));
-          }
 
-          // In any case, add the terminator as the current statement
-          // context for control edges.
-          EB.addContext(Term);
-        }
-
-        break;
-      }
-
-      if (Optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
-        Optional<CFGElement> First = BE->getFirstElement();
-        if (Optional<CFGStmt> S = First ? First->getAs<CFGStmt>() : None) {
-          const Stmt *stmt = S->getStmt();
-          if (IsControlFlowExpr(stmt)) {
-            // Add the proper context for '&&', '||', and '?'.
-            EB.addContext(stmt);
-          }
-          else
-            EB.addExtendedContext(PDB.getEnclosingStmtLocation(stmt).asStmt());
-        }
-
-        break;
-      }
+  } else if (Optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
+}
+
+//===----------------------------------------------------------------------===//
+// Top-level logic for generating extensive path diagnostics.
+//===----------------------------------------------------------------------===//
+
+static bool GenerateExtensivePathDiagnostic(
+    PathDiagnostic &PD, PathDiagnosticBuilder &PDB, const ExplodedNode *N,
+    LocationContextMap &LCM,
+    ArrayRef<std::unique_ptr<BugReporterVisitor>> visitors) {
+  EdgeBuilder EB(PD, PDB);
+  StackDiagVector CallStack;
 
+  InterestingExprs IE;
+  const ExplodedNode *NextNode = N->pred_empty() ? nullptr : *(N->pred_begin());
+  while (NextNode) {
+    N = NextNode;
+    NextNode = N->getFirstPred();
 
-    } while (0);
+    generateExtensiveDiagnosticsForNode(N, PDB, LCM, EB, CallStack, PD, IE);
 
     if (!NextNode)
       continue;
 
     // Add pieces from custom visitors.
     BugReport *R = PDB.getBugReport();
     llvm::FoldingSet<PathDiagnosticPiece> DeduplicationSet;
     for (auto &V : visitors) {

 
 static const char StrEnteringLoop[] = "Entering loop body";
 static const char StrLoopBodyZero[] = "Loop body executed 0 times";
 static const char StrLoopRangeEmpty[] =
   "Loop body skipped when range is empty";
 static const char StrLoopCollectionEmpty[] =
   "Loop body skipped when collection is empty";
 
-static bool GenerateAlternateExtensivePathDiagnostic(
-    PathDiagnostic &PD, PathDiagnosticBuilder &PDB, const ExplodedNode *N,
+/// Generate alternate-extensive diagnostics for the node \p N,
+/// and write it into \p PD.
+static void generateAlternateExtensiveDiagnosticsForNode(const ExplodedNode *N,
+      PathDiagnostic &PD,
+      PathDiagnosticLocation &PrevLoc,
+      PathDiagnosticBuilder &PDB,
       LocationContextMap &LCM,
-    ArrayRef<std::unique_ptr<BugReporterVisitor>> visitors) {
-
-  BugReport *report = PDB.getBugReport();
-  const SourceManager& SM = PDB.getSourceManager();
-  StackDiagVector CallStack;
-  InterestingExprs IE;
-
-  PathDiagnosticLocation PrevLoc = PD.getLocation();
-
+      StackDiagVector &CallStack,
+      InterestingExprs &IE) {
   const ExplodedNode *NextNode = N->getFirstPred();
-  while (NextNode) {
-    N = NextNode;
-    NextNode = N->getFirstPred();
-    ProgramPoint P = N->getLocation();
+  const SourceManager& SM = PDB.getSourceManager();
 
-    do {
-      // Have we encountered an entrance to a call?  It may be
-      // the case that we have not encountered a matching
-      // call exit before this point.  This means that the path
-      // terminated within the call itself.
-      if (Optional<CallEnter> CE = P.getAs<CallEnter>()) {
-        // Add an edge to the start of the function.
-        const StackFrameContext *CalleeLC = CE->getCalleeContext();
-        const Decl *D = CalleeLC->getDecl();
-        // Add the edge only when the callee has body. We jump to the beginning
-        // of the *declaration*, however we expect it to be followed by the
-        // body. This isn't the case for autosynthesized property accessors in
-        // Objective-C. No need for a similar extra check for CallExit points
-        // because the exit edge comes from a statement (i.e. return),
-        // not from declaration.
-        if (D->hasBody())
-          addEdgeToPath(PD.getActivePath(), PrevLoc,
-                        PathDiagnosticLocation::createBegin(D, SM), CalleeLC);
 
-        // Did we visit an entire call?
-        bool VisitedEntireCall = PD.isWithinCall();
-        PD.popActivePath();
 
-        PathDiagnosticCallPiece *C;
-        if (VisitedEntireCall) {
-          PathDiagnosticPiece *P = PD.getActivePath().front().get();
-          C = cast<PathDiagnosticCallPiece>(P);
-        } else {
-          const Decl *Caller = CE->getLocationContext()->getDecl();
-          C = PathDiagnosticCallPiece::construct(PD.getActivePath(), Caller);
 
-          // Since we just transferred the path over to the call piece,
-          // reset the mapping from active to location context.
-          assert(PD.getActivePath().size() == 1 &&
-                 PD.getActivePath().front().get() == C);
-          LCM[&PD.getActivePath()] = nullptr;
 
-          // Record the location context mapping for the path within
-          // the call.
-          assert(LCM[&C->path] == nullptr ||
-                 LCM[&C->path] == CE->getCalleeContext());
-          LCM[&C->path] = CE->getCalleeContext();
 
-          // If this is the first item in the active path, record
-          // the new mapping from active path to location context.
-          const LocationContext *&NewLC = LCM[&PD.getActivePath()];
-          if (!NewLC)
-            NewLC = N->getLocationContext();
 
-          PDB.LC = NewLC;
-        }
-        C->setCallee(*CE, SM);
 
-        // Update the previous location in the active path.
-        PrevLoc = C->getLocation();
 
-        if (!CallStack.empty()) {
-          assert(CallStack.back().first == C);
-          CallStack.pop_back();
-        }
-        break;
-      }
+    return;
 
-      // Query the location context here and the previous location
-      // as processing CallEnter may change the active path.
-      PDB.LC = N->getLocationContext();
 
-      // Record the mapping from the active path to the location
-      // context.
-      assert(!LCM[&PD.getActivePath()] ||
-             LCM[&PD.getActivePath()] == PDB.LC);
-      LCM[&PD.getActivePath()] = PDB.LC;
 
-      // Have we encountered an exit from a function call?
-      if (Optional<CallExitEnd> CE = P.getAs<CallExitEnd>()) {
-        const Stmt *S = CE->getCalleeContext()->getCallSite();
-        // Propagate the interesting symbols accordingly.
-        if (const Expr *Ex = dyn_cast_or_null<Expr>(S)) {
-          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
-                                              N->getState().get(), Ex,
-                                              N->getLocationContext());
-        }
 
-        // We are descending into a call (backwards).  Construct
-        // a new call piece to contain the path pieces for that call.
-        auto C = PathDiagnosticCallPiece::construct(N, *CE, SM);
 
-        // Record the location context for this call piece.
-        LCM[&C->path] = CE->getCalleeContext();
 
-        // Add the edge to the return site.
-        addEdgeToPath(PD.getActivePath(), PrevLoc, C->callReturn, PDB.LC);
-        auto *P = C.get();
-        PD.getActivePath().push_front(std::move(C));
-        PrevLoc.invalidate();
 
-        // Make the contents of the call the active path for now.
-        PD.pushActivePath(&P->path);
-        CallStack.push_back(StackDiagPair(P, N));
-        break;
-      }
-
-      if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
-        // For expressions, make sure we propagate the
-        // interesting symbols correctly.
-        if (const Expr *Ex = PS->getStmtAs<Expr>())
-          reversePropagateIntererstingSymbols(*PDB.getBugReport(), IE,
-                                              N->getState().get(), Ex,
-                                              N->getLocationContext());
+  } else if (Optional<PostStmt> PS = P.getAs<PostStmt>()) {
 
-        // Add an edge.  If this is an ObjCForCollectionStmt do
-        // not add an edge here as it appears in the CFG both
-        // as a terminator and as a terminator condition.
-        if (!isa<ObjCForCollectionStmt>(PS->getStmt())) {
-          PathDiagnosticLocation L =
-            PathDiagnosticLocation(PS->getStmt(), SM, PDB.LC);
-          addEdgeToPath(PD.getActivePath(), PrevLoc, L, PDB.LC);
-        }
-        break;
-      }
-
-      // Block edges.
-      if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
-        // Does this represent entering a call?  If so, look at propagating
-        // interesting symbols across call boundaries.
-        if (NextNode) {
-          const LocationContext *CallerCtx = NextNode->getLocationContext();
-          const LocationContext *CalleeCtx = PDB.LC;
-          if (CallerCtx != CalleeCtx) {
-            reversePropagateInterestingSymbols(*PDB.getBugReport(), IE,
-                                               N->getState().get(),
-                                               CalleeCtx, CallerCtx);
-          }
-        }
+  } else if (Optional<BlockEdge> BE = P.getAs<BlockEdge>()) {
 
-        // Are we jumping to the head of a loop?  Add a special diagnostic.
-        if (const Stmt *Loop = BE->getSrc()->getLoopTarget()) {
-          PathDiagnosticLocation L(Loop, SM, PDB.LC);
-          const Stmt *Body = nullptr;
 
-          if (const ForStmt *FS = dyn_cast<ForStmt>(Loop))
-            Body = FS->getBody();
-          else if (const WhileStmt *WS = dyn_cast<WhileStmt>(Loop))
-            Body = WS->getBody();
-          else if (const ObjCForCollectionStmt *OFS =
-                     dyn_cast<ObjCForCollectionStmt>(Loop)) {
-            Body = OFS->getBody();
-          } else if (const CXXForRangeStmt *FRS =
-                       dyn_cast<CXXForRangeStmt>(Loop)) {
-            Body = FRS->getBody();
-          }
-          // do-while statements are explicitly excluded here
 
-          auto p = std::make_shared<PathDiagnosticEventPiece>(
-              L, "Looping back to the head "
-                 "of the loop");
-          p->setPrunable(true);
 
-          addEdgeToPath(PD.getActivePath(), PrevLoc, p->getLocation(), PDB.LC);
-          PD.getActivePath().push_front(std::move(p));
 
-          if (const CompoundStmt *CS = dyn_cast_or_null<CompoundStmt>(Body)) {
-            addEdgeToPath(PD.getActivePath(), PrevLoc,
-                          PathDiagnosticLocation::createEndBrace(CS, SM),
-                          PDB.LC);
-          }
-        }
 
-        const CFGBlock *BSrc = BE->getSrc();
-        ParentMap &PM = PDB.getParentMap();
 
-        if (const Stmt *Term = BSrc->getTerminator()) {
-          // Are we jumping past the loop body without ever executing the
-          // loop (because the condition was false)?
-          if (isLoop(Term)) {
-            const Stmt *TermCond = getTerminatorCondition(BSrc);
-            bool IsInLoopBody =
-              isInLoopBody(PM, getStmtBeforeCond(PM, TermCond, N), Term);
 
-            const char *str = nullptr;
 
-            if (isJumpToFalseBranch(&*BE)) {
-              if (!IsInLoopBody) {
-                if (isa<ObjCForCollectionStmt>(Term)) {
-                  str = StrLoopCollectionEmpty;
-                } else if (isa<CXXForRangeStmt>(Term)) {
-                  str = StrLoopRangeEmpty;
-                } else {
-                  str = StrLoopBodyZero;
-                }
-              }
-            } else {
-              str = StrEnteringLoop;
-            }
 
-            if (str) {
-              PathDiagnosticLocation L(TermCond ? TermCond : Term, SM, PDB.LC);
-              auto PE = std::make_shared<PathDiagnosticEventPiece>(L, str);
-              PE->setPrunable(true);
-              addEdgeToPath(PD.getActivePath(), PrevLoc,
-                            PE->getLocation(), PDB.LC);
-              PD.getActivePath().push_front(std::move(PE));
-            }
-          } else if (isa<BreakStmt>(Term) || isa<ContinueStmt>(Term) ||
-                     isa<GotoStmt>(Term)) {
-            PathDiagnosticLocation L(Term, SM, PDB.LC);
-            addEdgeToPath(PD.getActivePath(), PrevLoc, L, PDB.LC);
-          }
-        }
-        break;
-      }
-    } while (0);
+}
+
+static bool GenerateAlternateExtensivePathDiagnostic(
+    PathDiagnostic &PD, PathDiagnosticBuilder &PDB, const ExplodedNode *N,
+    LocationContextMap &LCM,
+    ArrayRef<std::unique_ptr<BugReporterVisitor>> visitors) {
+
+  BugReport *report = PDB.getBugReport();
+  const SourceManager& SM = PDB.getSourceManager();
+  StackDiagVector CallStack;
+  InterestingExprs IE;
+
+  PathDiagnosticLocation PrevLoc = PD.getLocation();
+
+  const ExplodedNode *NextNode = N->getFirstPred();
+  while (NextNode) {
+    N = NextNode;
+    NextNode = N->getFirstPred();
+
+    generateAlternateExtensiveDiagnosticsForNode(
+        N, PD, PrevLoc, PDB, LCM, CallStack, IE);
 
     if (!NextNode)
       continue;
 
     // Add pieces from custom visitors.
     llvm::FoldingSet<PathDiagnosticPiece> DeduplicationSet;
     for (auto &V : visitors) {
       if (auto p = V->VisitNode(N, NextNode, PDB, *report)) {