[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, 0 insertions, 22 deletions

diff --git a/lib/StaticAnalyzer/Core/ExprEngine.cpp b/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 9b0e66fffb..f7022c6482 100644
--- a/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -24,7 +24,6 @@
 #include "clang/AST/DeclCXX.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/SourceManager.h"
-#include "clang/Basic/SourceManager.h"
 #include "clang/Basic/PrettyStackTrace.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/ImmutableList.h"
@@ -158,27 +157,6 @@ const ProgramState *ExprEngine::getInitialState(const LocationContext *InitLoc)
   return state;
 }
 
-bool
-ExprEngine::doesInvalidateGlobals(const CallOrObjCMessage &callOrMessage) const
-{
-  if (callOrMessage.isFunctionCall() && !callOrMessage.isCXXCall()) {
-    SVal calleeV = callOrMessage.getFunctionCallee();
-    if (const FunctionTextRegion *codeR =
-          dyn_cast_or_null<FunctionTextRegion>(calleeV.getAsRegion())) {
-      
-      const FunctionDecl *fd = codeR->getDecl();
-      if (const IdentifierInfo *ii = fd->getIdentifier()) {
-        StringRef fname = ii->getName();
-        if (fname == "strlen")
-          return false;
-      }
-    }
-  }
-  
-  // The conservative answer: invalidates globals.
-  return true;
-}
-
 //===----------------------------------------------------------------------===//
 // Top-level transfer function logic (Dispatcher).
 //===----------------------------------------------------------------------===//