Add 'MemRegion::getBaseRegion()', a utility method to strip ElementRegions with

index 0.  This will be used for refinements to InvalidateRegion and CastRegion.

llvm-svn: 77481

clang/include/clang/Analysis/PathSensitive/MemRegion.h

@@ -70,6 +70,8 @@ public:
   std::string getString() const;
   
   const MemSpaceRegion *getMemorySpace() const;
+  
+  const MemRegion *getBaseRegion() const;
     
   bool hasStackStorage() const;
   

clang/include/clang/Analysis/PathSensitive/SVals.h

@@ -371,6 +371,8 @@ public:
     return static_cast<MemRegion*>(Data);
   }
   
+  const MemRegion* getBaseRegion() const;
+  
   template <typename REGION>
   const REGION* getRegionAs() const {
     return llvm::dyn_cast<REGION>(getRegion());

clang/lib/Analysis/MemRegion.cpp

@@ -398,3 +398,23 @@ const MemRegion *TypedViewRegion::removeViews() const {
   }
   return R;
 }
+
+const MemRegion *MemRegion::getBaseRegion() const {
+  const MemRegion *R = this;
+  while (true) {
+    if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) {      
+      // FIXME: generalize.  Essentially we want to strip away ElementRegions
+      // that were layered on a symbolic region because of casts.  We only
+      // want to strip away ElementRegions, however, where the index is 0.
+      SVal index = ER->getIndex();
+      if (nonloc::ConcreteInt *CI = dyn_cast<nonloc::ConcreteInt>(&index)) {
+        if (CI->getValue().getZExtValue() == 0) {
+          R = ER->getSuperRegion();
+          continue;
+        }
+      }
+    }
+    break;
+  }
+  return R;
+}

clang/lib/Analysis/SVals.cpp

@@ -72,7 +72,7 @@ const FunctionDecl* SVal::getAsFunctionDecl() const {
 // FIXME: should we consider SymbolRef wrapped in CodeTextRegion?
 SymbolRef SVal::getAsLocSymbol() const {
   if (const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(this)) {
-    const MemRegion *R = X->getRegion();
+    const MemRegion *R = X->getBaseRegion();
     
     while (R) {
       // Blast through region views.
@@ -80,7 +80,6 @@ SymbolRef SVal::getAsLocSymbol() const {
         R = View->getSuperRegion();
         continue;
       }
-      
       if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(R))
         return SymR->getSymbol();
       
@@ -121,6 +120,11 @@ const MemRegion *SVal::getAsRegion() const {
   return 0;
 }
 
+const MemRegion *loc::MemRegionVal::getBaseRegion() const {
+  const MemRegion *R = getRegion();
+  return R ?  R->getBaseRegion() : NULL;
+}
+
 bool SVal::symbol_iterator::operator==(const symbol_iterator &X) const {
   return itr == X.itr;
 }