StoreManager::CastRegion:

- Don't layer TypedViewRegions on top of any region except
  SymbolicRegions and AllocaRegions.  This follows from my offline
  discussion within Zhongxing about how TypedViewRegions really only
  represent memory getting re-appropriated for a new purpose.

Fallout	from this change:
- Move test case from xfail_rdar_6440393.m to misc-ps-64.m
  (it now passes).

- test/Analysis/fields.c now fails for region store (crash).
  Marking XFAIL.

- test/Analysis/rdar-6441136-region.c now fails (only runs with region store).
  Marking XFAIL.

  Diagnosis: The analyzer now correctly identifies an early out-of-bounds memory
   access then the one flagged:

  rdar-6541136-region.c:17:3: warning: Load or store into an out-of-bound memory position.
    *p = 1;
    ^~

  Changing the line:
   char *p = (void*) &wonky[1];
  to
   char *p = (void*) &wonky[0];

  (which should delay the buffer overrun) causes region store to crash, probably
  because it expects a TypedViewRegion.

- test/Analysis/casts.c (region store) now fails (crash).
  Marking XFAIL.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70565 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 4 deletions

diff --git a/lib/Analysis/Store.cpp b/lib/Analysis/Store.cpp
index 6464c57df0..65e90dec33 100644
--- a/lib/Analysis/Store.cpp
+++ b/lib/Analysis/Store.cpp
@@ -59,9 +59,15 @@ StoreManager::CastRegion(const GRState* state, const MemRegion* R,
       return CastResult(state, R);
     }
 
-  // FIXME: We don't want to layer region views.  Need to handle
-  // arbitrary downcasts.
+  // FIXME: Need to handle arbitrary downcasts.
+  // FIXME: Handle the case where a TypedViewRegion (layering a SymbolicRegion
+  //         or an AllocaRegion is cast to another view, thus causing the memory
+  //         to be re-used for a different purpose.
 
-  const MemRegion* ViewR = MRMgr.getTypedViewRegion(CastToTy, R);  
-  return CastResult(AddRegionView(state, ViewR, R), ViewR);
+  if (isa<SymbolicRegion>(R) || isa<AllocaRegion>(R)) {
+    const MemRegion* ViewR = MRMgr.getTypedViewRegion(CastToTy, R);  
+    return CastResult(AddRegionView(state, ViewR, R), ViewR);
+  }
+  
+  return CastResult(state, R);
 }