[analyzer] Implement a methond to discover origin region of a symbol.

This encourages checkers to make logical decisions depending on
value of which region was the symbol under consideration
introduced to denote.

A similar technique is already used in a couple of checkers;
they were modified to call the new method.

Differential Revision: http://reviews.llvm.org/D22242

llvm-svn: 275290

1 files changed, 1 insertions, 9 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
index 50915f399a1..9e863e79e41 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
@@ -315,15 +315,7 @@ void ObjCDeallocChecker::checkBeginFunction(
 /// Returns nullptr if the instance symbol cannot be found.
 const ObjCIvarRegion *
 ObjCDeallocChecker::getIvarRegionForIvarSymbol(SymbolRef IvarSym) const {
-  const MemRegion *RegionLoadedFrom = nullptr;
-  if (auto *DerivedSym = dyn_cast<SymbolDerived>(IvarSym))
-    RegionLoadedFrom = DerivedSym->getRegion();
-  else if (auto *RegionSym = dyn_cast<SymbolRegionValue>(IvarSym))
-    RegionLoadedFrom = RegionSym->getRegion();
-  else
-    return nullptr;
-
-  return dyn_cast<ObjCIvarRegion>(RegionLoadedFrom);
+  return dyn_cast_or_null<ObjCIvarRegion>(IvarSym->getOriginRegion());
 }
 
 /// Given a symbol for an ivar, return a symbol for the instance containing