[OpenMP] Fix mapping of scalars for combined directives

Combined directives like 'target parallel' have two captured statements.
Sema has to check the right one from the right direction.

Previously, Sema::IsOpenMPCapturedByRef would return false for mapped
scalars on combined directives. This results in a wrong signature of
the outlined function which triggers an assertion:
void llvm::CallInst::init(llvm::FunctionType *, llvm::Value *, ArrayRef<llvm::Value *>, ArrayRef<OperandBundleDef>, const llvm::Twine &): Assertion `(i >= FTy->getNumParams() || FTy->getParamType(i) == Args[i]->getType()) && "Calling a function with a bad signature!"' failed.

Fixes PR30975 (and PR31985). New function was taken from clang-ykt.

Differential Revision: https://reviews.llvm.org/D34888

llvm-svn: 306956
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 2b7733d..49da0e4 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -412,6 +412,30 @@
     return false;
   }
 
+  /// Do the check specified in \a Check to all component lists at a given level
+  /// and return true if any issue is found.
+  bool checkMappableExprComponentListsForDeclAtLevel(
+      ValueDecl *VD, unsigned Level,
+      const llvm::function_ref<
+          bool(OMPClauseMappableExprCommon::MappableExprComponentListRef,
+               OpenMPClauseKind)> &Check) {
+    if (isStackEmpty())
+      return false;
+
+    auto StartI = Stack.back().first.begin();
+    auto EndI = Stack.back().first.end();
+    if (std::distance(StartI, EndI) <= (int)Level)
+      return false;
+    std::advance(StartI, Level);
+
+    auto MI = StartI->MappedExprComponents.find(VD);
+    if (MI != StartI->MappedExprComponents.end())
+      for (auto &L : MI->second.Components)
+        if (Check(L, MI->second.Kind))
+          return true;
+    return false;
+  }
+
   /// Create a new mappable expression component list associated with a given
   /// declaration and initialize it with the provided list of components.
   void addMappableExpressionComponents(
@@ -994,9 +1018,8 @@
     bool IsVariableUsedInMapClause = false;
     bool IsVariableAssociatedWithSection = false;
 
-    DSAStack->checkMappableExprComponentListsForDecl(
-        D, /*CurrentRegionOnly=*/true,
-        [&](OMPClauseMappableExprCommon::MappableExprComponentListRef
+    DSAStack->checkMappableExprComponentListsForDeclAtLevel(
+        D, Level, [&](OMPClauseMappableExprCommon::MappableExprComponentListRef
                 MapExprComponents,
             OpenMPClauseKind WhereFoundClauseKind) {
           // Only the map clause information influences how a variable is