[analyzer] Terminate analysis on OpenMP code instead of crashing

[a.sidorin]

Summary

ExprEngine assumes that OpenMP statements should never appear in CFG. However, current CFG doesn't know anything about OpenMP and passes such statements as CFG nodes causing "UNREACHABLE executed!" crashes. Since I have no ideas on OpenMP implementation in ExprEngine or CFG, I'm changing the behaviour to stop the analysis on OpenMP statements to avoid crashes.

[a.sidorin]

git blame shows that OMP* statements were added to the switch block by different authors while OpenMP support in clang was implemented. Looks like they were put to "Should not appear" section instead of "Unsupported" by mistake.

[dcoughlin]

Thanks for fixing this! It looks like this is tracked by PR31835. https://bugs.llvm.org//show_bug.cgi?id=31835

[a.sidorin]

Thank you Devin. Should we submit this to 4.0? I guess there are not many users of both CSA and OpenMP but PR you pointed is already the second report about this issue I see.

[dcoughlin]

@zaks.anna: What do you think? Should we try to get this into clang 4.0?

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

PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
                                 S->getLocStart(),
                                 "Error evaluating statement");
   ExplodedNodeSet Dst;
   StmtNodeBuilder Bldr(Pred, DstTop, *currBldrCtx);
 
   assert(!isa<Expr>(S) || S == cast<Expr>(S)->IgnoreParens());
 
   switch (S->getStmtClass()) {
-    // C++ and ARC stuff we don't support yet.
+    // C++, OpenMP and ARC stuff we don't support yet.
     case Expr::ObjCIndirectCopyRestoreExprClass:
     case Stmt::CXXDependentScopeMemberExprClass:
     case Stmt::CXXInheritedCtorInitExprClass:
     case Stmt::CXXTryStmtClass:
     case Stmt::CXXTypeidExprClass:
     case Stmt::CXXUuidofExprClass:
     case Stmt::CXXFoldExprClass:
     case Stmt::MSPropertyRefExprClass:
switch (S->getStmtClass()) {
     case Stmt::FunctionParmPackExprClass:
     case Stmt::CoroutineBodyStmtClass:
     case Stmt::CoawaitExprClass:
     case Stmt::CoreturnStmtClass:
     case Stmt::CoyieldExprClass:
     case Stmt::SEHTryStmtClass:
     case Stmt::SEHExceptStmtClass:
     case Stmt::SEHLeaveStmtClass:
-    case Stmt::SEHFinallyStmtClass: {
-      const ExplodedNode *node = Bldr.generateSink(S, Pred, Pred->getState());
-      Engine.addAbortedBlock(node, currBldrCtx->getBlock());
-      break;
-    }
-
-    case Stmt::ParenExprClass:
-      llvm_unreachable("ParenExprs already handled.");
-    case Stmt::GenericSelectionExprClass:
-      llvm_unreachable("GenericSelectionExprs already handled.");
-    // Cases that should never be evaluated simply because they shouldn't
-    // appear in the CFG.
-    case Stmt::BreakStmtClass:
-    case Stmt::CaseStmtClass:
-    case Stmt::CompoundStmtClass:
-    case Stmt::ContinueStmtClass:
-    case Stmt::CXXForRangeStmtClass:
-    case Stmt::DefaultStmtClass:
-    case Stmt::DoStmtClass:
-    case Stmt::ForStmtClass:
-    case Stmt::GotoStmtClass:
-    case Stmt::IfStmtClass:
-    case Stmt::IndirectGotoStmtClass:
-    case Stmt::LabelStmtClass:
-    case Stmt::NoStmtClass:
-    case Stmt::NullStmtClass:
-    case Stmt::SwitchStmtClass:
-    case Stmt::WhileStmtClass:
-    case Expr::MSDependentExistsStmtClass:
-    case Stmt::CapturedStmtClass:
+    case Stmt::SEHFinallyStmtClass:
     case Stmt::OMPParallelDirectiveClass:
     case Stmt::OMPSimdDirectiveClass:
     case Stmt::OMPForDirectiveClass:
     case Stmt::OMPForSimdDirectiveClass:
     case Stmt::OMPSectionsDirectiveClass:
     case Stmt::OMPSectionDirectiveClass:
     case Stmt::OMPSingleDirectiveClass:
     case Stmt::OMPMasterDirectiveClass:
switch (S->getStmtClass()) {
     case Stmt::OMPTeamsDistributeSimdDirectiveClass:
     case Stmt::OMPTeamsDistributeParallelForSimdDirectiveClass:
     case Stmt::OMPTeamsDistributeParallelForDirectiveClass:
     case Stmt::OMPTargetTeamsDirectiveClass:
     case Stmt::OMPTargetTeamsDistributeDirectiveClass:
     case Stmt::OMPTargetTeamsDistributeParallelForDirectiveClass:
     case Stmt::OMPTargetTeamsDistributeParallelForSimdDirectiveClass:
     case Stmt::OMPTargetTeamsDistributeSimdDirectiveClass:
+    case Stmt::CapturedStmtClass:
+    {
+      const ExplodedNode *node = Bldr.generateSink(S, Pred, Pred->getState());
+      Engine.addAbortedBlock(node, currBldrCtx->getBlock());
+      break;
+    }
+
+    case Stmt::ParenExprClass:
+      llvm_unreachable("ParenExprs already handled.");
+    case Stmt::GenericSelectionExprClass:
+      llvm_unreachable("GenericSelectionExprs already handled.");
+    // Cases that should never be evaluated simply because they shouldn't
+    // appear in the CFG.
+    case Stmt::BreakStmtClass:
+    case Stmt::CaseStmtClass:
+    case Stmt::CompoundStmtClass:
+    case Stmt::ContinueStmtClass:
+    case Stmt::CXXForRangeStmtClass:
+    case Stmt::DefaultStmtClass:
+    case Stmt::DoStmtClass:
+    case Stmt::ForStmtClass:
+    case Stmt::GotoStmtClass:
+    case Stmt::IfStmtClass:
+    case Stmt::IndirectGotoStmtClass:
+    case Stmt::LabelStmtClass:
+    case Stmt::NoStmtClass:
+    case Stmt::NullStmtClass:
+    case Stmt::SwitchStmtClass:
+    case Stmt::WhileStmtClass:
+    case Expr::MSDependentExistsStmtClass:
       llvm_unreachable("Stmt should not be in analyzer evaluation loop");
 
     case Stmt::ObjCSubscriptRefExprClass:
     case Stmt::ObjCPropertyRefExprClass:
       llvm_unreachable("These are handled by PseudoObjectExpr");
 
     case Stmt::GNUNullExprClass: {
       // GNU __null is a pointer-width integer, not an actual pointer.

cfe/trunk/test/Analysis/openmp-unsupported.c

+// RUN: %clang_cc1 -triple i386-apple-darwin10 -analyze -analyzer-checker=core.builtin -fopenmp -verify %s
+// expected-no-diagnostics
+
+void openmp_parallel_crash_test() {
+#pragma omp parallel
+  ;
+}