Disallow the use of UnknownVal as the index for ElementRegions. UnknownVals can be used as

the index when the value evaluation isn't powerful enough.  By creating ElementRegions with
UnknownVals as the index, this gives the false impression that they are the same element, when
they really aren't.  This becomes really problematic when deriving symbols from these regions
(e.g., those representing the initial value of the index), since two different indices will
get the same symbol for their binding.

This fixes an issue with the idempotent operations checker that would cause two indices that
are clearly not the same to make it appear as if they always had the same value.

Fixes <rdar://problem/8431728>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@113920 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 6 deletions

diff --git a/lib/Checker/Store.cpp b/lib/Checker/Store.cpp
index 1cb5cd70ca..aaa518edc8 100644
--- a/lib/Checker/Store.cpp
+++ b/lib/Checker/Store.cpp
@@ -28,7 +28,7 @@ Store StoreManager::EnterStackFrame(const GRState *state,
 
 const MemRegion *StoreManager::MakeElementRegion(const MemRegion *Base,
                                               QualType EleTy, uint64_t index) {
-  SVal idx = ValMgr.makeArrayIndex(index);
+  NonLoc idx = ValMgr.makeArrayIndex(index);
   return MRMgr.getElementRegion(EleTy, idx, Base, ValMgr.getContext());
 }
 
@@ -45,7 +45,7 @@ static bool IsCompleteType(ASTContext &Ctx, QualType Ty) {
 
 const ElementRegion *StoreManager::GetElementZeroRegion(const MemRegion *R, 
                                                         QualType T) {
-  SVal idx = ValMgr.makeZeroArrayIndex();
+  NonLoc idx = ValMgr.makeZeroArrayIndex();
   assert(!T.isNull());
   return MRMgr.getElementRegion(T, idx, R, Ctx);
 }
@@ -267,7 +267,7 @@ SVal StoreManager::getLValueFieldOrIvar(const Decl* D, SVal Base) {
   return loc::MemRegionVal(MRMgr.getFieldRegion(cast<FieldDecl>(D), BaseR));
 }
 
-SVal StoreManager::getLValueElement(QualType elementType, SVal Offset, 
+SVal StoreManager::getLValueElement(QualType elementType, NonLoc Offset, 
                                     SVal Base) {
 
   // If the base is an unknown or undefined value, just return it back.
@@ -283,7 +283,7 @@ SVal StoreManager::getLValueElement(QualType elementType, SVal Offset,
   const ElementRegion *ElemR = dyn_cast<ElementRegion>(BaseRegion);
 
   // Convert the offset to the appropriate size and signedness.
-  Offset = ValMgr.convertToArrayIndex(Offset);
+  Offset = cast<NonLoc>(ValMgr.convertToArrayIndex(Offset));
 
   if (!ElemR) {
     //
@@ -322,8 +322,8 @@ SVal StoreManager::getLValueElement(QualType elementType, SVal Offset,
   assert(BaseIdxI.isSigned());
 
   // Compute the new index.
-  SVal NewIdx = nonloc::ConcreteInt(
-                      ValMgr.getBasicValueFactory().getValue(BaseIdxI + OffI));
+  nonloc::ConcreteInt NewIdx(ValMgr.getBasicValueFactory().getValue(BaseIdxI +
+                                                                    OffI));
 
   // Construct the new ElementRegion.
   const MemRegion *ArrayR = ElemR->getSuperRegion();