[analyzer] Revert the functional part of r155944.

The change resulted in multiple issues on the buildbot, so it's not
ready for prime time. Only enable history tracking for tainted
data(which is experimental) for now.

llvm-svn: 156049

clang/lib/StaticAnalyzer/Core/SValBuilder.cpp

@@ -199,6 +199,9 @@ SVal SValBuilder::makeSymExprValNN(ProgramStateRef State,
                                    BinaryOperator::Opcode Op,
                                    NonLoc LHS, NonLoc RHS,
                                    QualType ResultTy) {
+  if (!State->isTainted(RHS) && !State->isTainted(LHS))
+    return UnknownVal();
+    
   const SymExpr *symLHS = LHS.getAsSymExpr();
   const SymExpr *symRHS = RHS.getAsSymExpr();
 

clang/test/Analysis/malloc.c

@@ -776,13 +776,6 @@ int rdar11269741(struct rdar11269741_b_t o)
   return p->n.m; // expected-warning {{leak}}
 }
 
-// Pointer arithmetic, returning an ElementRegion.
-void *radar11329382(unsigned bl) {
-  void *ptr = malloc (16);
-  ptr = ptr + (2 - bl);
-  return ptr; // no warning
-}
-
 void __assert_rtn(const char *, const char *, int, const char *) __attribute__((__noreturn__));
 int strcmp(const char *, const char *);
 char *a (void);