[analyzer] Propagate taint through NonLoc to NonLoc casts.

 - Created a new SymExpr type - SymbolCast.
 - SymbolCast is created when we don't know how to simplify a NonLoc to
NonLoc casts.
 - A bit of code refactoring: introduced dispatchCast to have better
code reuse, remove a goto.
 - Updated the test case to showcase the new taint flow.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145985 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/StaticAnalyzer/Core/SVals.cpp b/lib/StaticAnalyzer/Core/SVals.cpp
index 4bdea1d9e1..97e5a1be4c 100644
--- a/lib/StaticAnalyzer/Core/SVals.cpp
+++ b/lib/StaticAnalyzer/Core/SVals.cpp
@@ -91,6 +91,7 @@ SymbolRef SVal::getLocSymbolInBase() const {
   return 0;
 }
 
+// TODO: The next 3 functions have to be simplified.
 /// getAsSymbol - If this Sval wraps a symbol return that SymbolRef.
 ///  Otherwise return 0.
 // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
@@ -168,6 +169,10 @@ void SVal::symbol_iterator::expand() {
   const SymExpr *SE = itr.back();
   itr.pop_back();
 
+  if (const SymbolCast *SC = dyn_cast<SymbolCast>(SE)) {
+    itr.push_back(SC->getOperand());
+    return;
+  }
   if (const SymIntExpr *SIE = dyn_cast<SymIntExpr>(SE)) {
     itr.push_back(SIE->getLHS());
     return;