[analyzer] tracking stores/constraints now works for ObjC ivars or struct fields.

This required more changes than I originally expected:

- ObjCIvarRegion implements "canPrintPretty" et al
- DereferenceChecker indicates the null pointer source is an ivar
- bugreporter::trackNullOrUndefValue() uses an alternate algorithm
  to compute the location region to track by scouring the ExplodedGraph.
  This allows us to get the actual MemRegion for variables, ivars,
  fields, etc.  We only hand construct a VarRegion for C++ references.
- ExplodedGraph no longer drops nodes for expressions that are marked
  'lvalue'.  This is to facilitate the logic in the previous bullet.
  This may lead to a slight increase in size in the ExplodedGraph,
  which I have not measured, but it is likely not to be a big deal.

I have validated each of the changed plist output.

Fixes <rdar://problem/12114812>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175988 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp b/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
index 3aa8aaac0d..72d46c50e1 100644
--- a/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
@@ -76,6 +76,14 @@ DereferenceChecker::AddDerefSource(raw_ostream &os,
       Ranges.push_back(SourceRange(L, L));
       break;
     }
+    case Stmt::ObjCIvarRefExprClass: {
+      const ObjCIvarRefExpr *IV = cast<ObjCIvarRefExpr>(Ex);
+      os << " (" << (loadedFrom ? "loaded from" : "via")
+         << " ivar '" << IV->getDecl()->getName() << "')";
+      SourceLocation L = IV->getLocation();
+      Ranges.push_back(SourceRange(L, L));
+      break;
+    }    
   }
 }