[analyzer] Use the CallEnter node to get a value for tracked null arguments.

Additionally, don't collect PostStore nodes -- they are often used in
path diagnostics.

Previously, we tried to track null arguments in the same way as any other
null values, but in many cases the necessary nodes had already been
collected (a memory optimization in ExplodedGraph). Now, we fall back to
using the value of the argument at the time of the call, which may not
always match the actual contents of the region, but often will.

This is a precursor to improving our suppression heuristic.
<rdar://problem/12350829>

llvm-svn: 166940

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
index 9b70d6861cc..c284bd7dfad 100644
--- a/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
@@ -61,7 +61,7 @@ bool ExplodedGraph::shouldCollect(const ExplodedNode *node) {
   //
   // (1) 1 predecessor (that has one successor)
   // (2) 1 successor (that has one predecessor)
-  // (3) The ProgramPoint is for a PostStmt.
+  // (3) The ProgramPoint is for a PostStmt, but not a PostStore.
   // (4) There is no 'tag' for the ProgramPoint.
   // (5) The 'store' is the same as the predecessor.
   // (6) The 'GDM' is the same as the predecessor.
@@ -85,7 +85,7 @@ bool ExplodedGraph::shouldCollect(const ExplodedNode *node) {
 
   // Condition 3.
   ProgramPoint progPoint = node->getLocation();
-  if (!isa<PostStmt>(progPoint))
+  if (!isa<PostStmt>(progPoint) || isa<PostStore>(progPoint))
     return false;
 
   // Condition 4.