Substantial Changes:

-ITE Simplification
-- Moved the utilities in src/theory/ite_simplifier.{h,cpp} to ite_utilities.
-- Separated simpWithCare from simpITE.
-- Disabled ite simplification on repeat simplification by default. Currently, ite simplification cannot help unless we internally make new constant leaf ites equal to constants.
-- simplifyWithCare() is now only run on QF_AUFBV by default. Speeds up nec benchmarks dramatically.
-- Added a new compress ites pass that is only run on QF_LIA by default.  This targets the perverse structure of ites generated during ite simplification on nec benchmarks.
-- After ite simplification, if the ite simplifier was used many times and the NodeManager's node pool is large enough, this garbage collects: zombies from the NodeManager repeatedly, the ite simplification caches, and the theory rewrite caches.

- TheoryEngine
-- Added TheoryEngine::donePPSimpITE() which orchestrates a number of ite simplifications above.
-- Switched UnconstrainedSimplifier to a pointer.

- RemoveITEs
-- Added a heuristic for checking whether or not a node contains term ites and if not, not bothering to invoke the rest of RemoveITE::run(). This safely changes the type of the cache used on misses of run. This cache can be cleared in the future. Currently disabled pending additional testing.

- TypeChecker
-- added a neverIsConst() rule to the typechecker. Operators that cannot be used in constructing constant expressions by computeIsConst() can now avoid caching on Node::isConst() calls.

- Theory Bool Rewriter
-- Added additional simplifications for boolean ites.

Minor Changes:

- TheoryModel
-- Removed vestigial copy of the ITESimplifier.
- AttributeManager
-- Fixed a garbage collection bug when deleting the node table caused the NodeManager to reclaimZombies() which caused memory corruption by deleting from the attributeManager.

- TypeChecker
-- added a neverIsConst() rule to the typechecker. Operators that cannot be used in constructing constant expressions by computeIsConst() can now avoid caching on Node::isConst() calls.

-NodeManager
-- Added additional functions for reclaiming zombies.
-- Exposed the size of the node pool for heuristics that worry about memory consumption.

- NaryBuilder
-- Added convenience classes for constructing associative and commutative n-ary operators.
-- Added a pass that turns associative and commutative n-ary operators into binary operators. (Mostly for printing expressions for strict parsers.)

1 files changed, 15 insertions, 3 deletions

diff --git a/src/expr/node_manager.h b/src/expr/node_manager.h
index 32c492003..af771bd89 100644
--- a/src/expr/node_manager.h
+++ b/src/expr/node_manager.h
@@ -229,8 +229,7 @@ class NodeManager {
     }
     d_zombies.insert(nv);// FIXME multithreading
 
-    if(!d_inReclaimZombies) {// FIXME multithreading
-      // for now, collect eagerly.  can add heuristic here later..
+    if(safeToReclaimZombies()) {
       if(d_zombies.size() > 5000) {
         reclaimZombies();
       }
@@ -243,6 +242,11 @@ class NodeManager {
   void reclaimZombies();
 
   /**
+   * It is safe to collect zombies.
+   */
+  bool safeToReclaimZombies() const;
+
+  /**
    * This template gives a mechanism to stack-allocate a NodeValue
    * with enough space for N children (where N is a compile-time
    * constant).  You use it like this:
@@ -860,6 +864,15 @@ public:
    */
   static inline TypeNode fromType(Type t);
 
+  /** Reclaim zombies while there are more than k nodes in the pool (if possible).*/
+  void reclaimZombiesUntil(uint32_t k);
+
+  /** Reclaims all zombies (if possible).*/
+  void reclaimAllZombies();
+
+  /** Size of the node pool. */
+  size_t poolSize() const;
+
   /** Deletes a list of attributes from the NM's AttributeManager.*/
   void deleteAttributes(const std::vector< const expr::attr::AttributeUniqueId* >& ids);
 
@@ -871,7 +884,6 @@ public:
    * any published code!
    */
   void debugHook(int debugFlag);
-
 };/* class NodeManager */
 
 /**