[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>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@166940 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 1 deletions

diff --git a/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitor.h b/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitor.h
index b4592c0fc9..a3784739d1 100644
--- a/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitor.h
+++ b/include/clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitor.h
@@ -258,7 +258,18 @@ public:
 
 namespace bugreporter {
 
-void trackNullOrUndefValue(const ExplodedNode *N, const Stmt *S, BugReport &R);
+/// Attempts to add visitors to trace a null or undefined value back to its
+/// point of origin, whether it is a symbol constrained to null or an explicit
+/// assignment.
+///
+/// \param N A node "downstream" from the evaluation of the statement.
+/// \param S The statement whose value is null or undefined.
+/// \param R The bug report to which visitors should be attached.
+/// \param IsArg Whether the statement is an argument to an inlined function.
+///              If this is the case, \p N \em must be the CallEnter node for
+///              the function.
+void trackNullOrUndefValue(const ExplodedNode *N, const Stmt *S, BugReport &R,
+                           bool IsArg = false);
 
 const Stmt *GetDerefExpr(const ExplodedNode *N);
 const Stmt *GetDenomExpr(const ExplodedNode *N);