[analyzer] Ensure BugReporterTracking works on regions with pointer arithmetic

Introduce a new helper function, which computes the first symbolic region in
the base region chain. The corresponding symbol has been used for assuming that
a pointer is null. Now, it will also be used for checking if it is null.

This ensures that we are tracking a null pointer correctly in the BugReporter.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179916 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/StaticAnalyzer/Core/MemRegion.cpp b/lib/StaticAnalyzer/Core/MemRegion.cpp
index cad42044b9..42073d4841 100644
--- a/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -1080,6 +1080,17 @@ const MemRegion *MemRegion::StripCasts(bool StripBaseCasts) const {
   }
 }
 
+const SymbolicRegion *MemRegion::getSymbolicBase() const {
+  const SubRegion *SubR = dyn_cast<SubRegion>(this);
+
+  while (SubR) {
+    if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SubR))
+      return SymR;
+    SubR = dyn_cast<SubRegion>(SubR->getSuperRegion());
+  }
+  return 0;
+}
+
 // FIXME: Merge with the implementation of the same method in Store.cpp
 static bool IsCompleteType(ASTContext &Ctx, QualType Ty) {
   if (const RecordType *RT = Ty->getAs<RecordType>()) {