From 0e3ec3ff2477e60f0ceda922cc2e3a25a59d81f2 Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Wed, 29 Jul 2009 18:14:27 +0000
Subject: [PATCH] Add 'MemRegion::getBaseRegion()', a utility method to strip
 ElementRegions with index 0.  This will be used for refinements to
 InvalidateRegion and CastRegion.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77481 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../clang/Analysis/PathSensitive/MemRegion.h  |  2 ++
 include/clang/Analysis/PathSensitive/SVals.h  |  2 ++
 lib/Analysis/MemRegion.cpp                    | 20 +++++++++++++++++++
 lib/Analysis/SVals.cpp                        |  8 ++++++--
 4 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/include/clang/Analysis/PathSensitive/MemRegion.h b/include/clang/Analysis/PathSensitive/MemRegion.h
index bcd195e75e..a65c71b5ec 100644
--- a/include/clang/Analysis/PathSensitive/MemRegion.h
+++ b/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;
   
diff --git a/include/clang/Analysis/PathSensitive/SVals.h b/include/clang/Analysis/PathSensitive/SVals.h
index 2ba370e532..63110c6fac 100644
--- a/include/clang/Analysis/PathSensitive/SVals.h
+++ b/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());
diff --git a/lib/Analysis/MemRegion.cpp b/lib/Analysis/MemRegion.cpp
index 9b8f7c81e1..a708bd3068 100644
--- a/lib/Analysis/MemRegion.cpp
+++ b/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;
+}
diff --git a/lib/Analysis/SVals.cpp b/lib/Analysis/SVals.cpp
index a5ba199398..6f480e8d46 100644
--- a/lib/Analysis/SVals.cpp
+++ b/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;
 }
-- 
2.40.0