Rework ExprEngine::evalLoad and clients (e.g. VisitBinaryOperator) so that when we generate a new ExplodedNode
we use the same Expr* as the one being currently visited.  This is preparation for transitioning to having
ProgramPoints refer to CFGStmts.

This required a bit of trickery.  We wish to keep the old Expr* bindings in the Environment intact,
as plenty of logic relies on it and there is no reason to change it, but we sometimes want the Stmt* for
the ProgramPoint to be different than the Expr* being used for bindings.  This requires adding an extra
argument for some functions (e.g., evalLocation).  This looks a bit strange for some clients, but
it will look a lot cleaner when were start using CFGStmt* in the appropriate places.

As some fallout, the diagnostics arrows are a bit difference, since some of the node locations have changed.
I have audited these, and they look reasonable.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154214 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/OSAtomicChecker.cpp b/lib/StaticAnalyzer/Checkers/OSAtomicChecker.cpp
index dc806c5..7b724d2 100644
--- a/lib/StaticAnalyzer/Checkers/OSAtomicChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/OSAtomicChecker.cpp
@@ -120,8 +120,8 @@
       dyn_cast_or_null<TypedValueRegion>(location.getAsRegion())) {
     LoadTy = TR->getValueType();
   }
-  Eng.evalLoad(Tmp, theValueExpr, Pred,
-                  state, location, &OSAtomicLoadTag, LoadTy);
+  Eng.evalLoad(Tmp, CE, theValueExpr, Pred,
+               state, location, &OSAtomicLoadTag, LoadTy);
 
   if (Tmp.empty()) {
     // If no nodes were generated, other checkers must have generated sinks. 
@@ -172,8 +172,8 @@
         val = svalBuilder.evalCast(val,R->getValueType(), newValueExpr->getType());
       }
 
-      Eng.evalStore(TmpStore, NULL, theValueExpr, N,
-                       stateEqual, location, val, &OSAtomicStoreTag);
+      Eng.evalStore(TmpStore, CE, theValueExpr, N,
+                    stateEqual, location, val, &OSAtomicStoreTag);
 
       if (TmpStore.empty()) {
         // If no nodes were generated, other checkers must have generated sinks.