[analyzer] Be less pessimistic about invalidation of global variables

as a result of a call.

Problem:
Global variables, which come in from system libraries should not be
invalidated by all calls. Also, non-system globals should not be
invalidated by system calls.

Solution:
The following solution to invalidation of globals seems flexible enough
for taint (does not invalidate stdin) and should not lead to too
many false positives. We split globals into 3 classes:

* immutable - values are preserved by calls (unless the specific
global is passed in as a parameter):
     A :  Most system globals and const scalars

* invalidated by functions defined in system headers:
     B: errno

* invalidated by all other functions (note, these functions may in
turn contain system calls):
     B: errno
     C: all other globals (which are not in A nor B)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147569 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/StaticAnalyzer/Core/Store.cpp b/lib/StaticAnalyzer/Core/Store.cpp
index 825510e00b..543f87879d 100644
--- a/lib/StaticAnalyzer/Core/Store.cpp
+++ b/lib/StaticAnalyzer/Core/Store.cpp
@@ -101,8 +101,10 @@ const MemRegion *StoreManager::castRegion(const MemRegion *R, QualType CastToTy)
     case MemRegion::StackArgumentsSpaceRegionKind:
     case MemRegion::HeapSpaceRegionKind:
     case MemRegion::UnknownSpaceRegionKind:
-    case MemRegion::NonStaticGlobalSpaceRegionKind:
-    case MemRegion::StaticGlobalSpaceRegionKind: {
+    case MemRegion::StaticGlobalSpaceRegionKind:
+    case MemRegion::GlobalInternalSpaceRegionKind:
+    case MemRegion::GlobalSystemSpaceRegionKind:
+    case MemRegion::GlobalImmutableSpaceRegionKind: {
       llvm_unreachable("Invalid region cast");
     }