new: persistent ptree (-write-ptree) and klee-ptree

Introduce three different kinds of process trees:
1. Noop: does nothing (e.g. no allocations for DFS)
2. InMemory: same behaviour as before (e.g. RandomPathSearcher)
3. Persistent: similar to InMemory but writes nodes to ptree.db
     and tracks information such as branch type, termination
     type or source location (asm) in nodes. Enabled with
     -write-ptree

ptree.db files can be analysed/plotted with the new "klee-ptree"
tool.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/Core/Searcher.h b/lib/Core/Searcher.h
index e399c616..ddd49264 100644
--- a/lib/Core/Searcher.h
+++ b/lib/Core/Searcher.h
@@ -172,7 +172,7 @@ namespace klee {
   ///
   /// The ownership bits are maintained in the update method.
   class RandomPathSearcher final : public Searcher {
-    PTree &processTree;
+    InMemoryPTree *processTree;
     RNG &theRNG;
 
     // Unique bitmask of this searcher
@@ -181,7 +181,7 @@ namespace klee {
   public:
     /// \param processTree The process tree.
     /// \param RNG A random number generator.
-    RandomPathSearcher(PTree &processTree, RNG &rng);
+    RandomPathSearcher(InMemoryPTree *processTree, RNG &rng);
     ~RandomPathSearcher() override = default;
 
     ExecutionState &selectState() override;