[analyzer] Add an option to re-analyze a dead-end path without inlining.

The analyzer gives up path exploration under certain conditions. For
example, when the same basic block has been visited more than 4 times.
With inlining turned on, this could lead to decrease in code coverage.
Specifically, if we give up inside the inlined function, the rest of
parent's basic blocks will not get analyzed.

This commit introduces an option to enable re-run along the failed path,
in which we do not inline the last inlined call site. This is done by
enqueueing the node before the processing of the inlined call site
with a special policy encoded in the state. The policy tells us not to
inline the call site along the path.

This lead to ~10% increase in the number of paths analyzed. Even though
we expected a much greater coverage improvement. 

The option is turned off by default for now.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@153534 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 1 deletions

diff --git a/include/clang/Analysis/ProgramPoint.h b/include/clang/Analysis/ProgramPoint.h
index 413b3cf4ea..e7bcf19bde 100644
--- a/include/clang/Analysis/ProgramPoint.h
+++ b/include/clang/Analysis/ProgramPoint.h
@@ -51,7 +51,8 @@ public:
               CallEnterKind,
               CallExitKind,
               MinPostStmtKind = PostStmtKind,
-              MaxPostStmtKind = CallExitKind };
+              MaxPostStmtKind = CallExitKind,
+              EpsilonKind};
 
 private:
   std::pair<const void *, const void *> Data;
@@ -380,6 +381,21 @@ public:
   }
 };
 
+/// This is a meta program point, which should be skipped by all the diagnostic
+/// reasoning etc.
+class EpsilonPoint : public ProgramPoint {
+public:
+  EpsilonPoint(const LocationContext *L, const void *Data1,
+               const void *Data2 = 0, const ProgramPointTag *tag = 0)
+    : ProgramPoint(Data1, Data2, EpsilonKind, L, tag) {}
+
+  const void *getData() const { return getData1(); }
+
+  static bool classof(const ProgramPoint* Location) {
+    return Location->getKind() == EpsilonKind;
+  }
+};
+
 /// ProgramPoints can be "tagged" as representing points specific to a given
 /// analysis entity.  Tags are abstract annotations, with an associated
 /// description and potentially other information.