From dd31916953ecc29514499e5c1cb96e3ae33ff3b8 Mon Sep 17 00:00:00 2001
From: Andrew Reynolds <andrew.j.reynolds@gmail.com>
Date: Wed, 29 Nov 2017 16:11:09 -0600
Subject: Improve caching in term formula removal (#1398)

---
 src/smt/term_formula_removal.h | 47 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 6 deletions(-)

(limited to 'src/smt/term_formula_removal.h')

diff --git a/src/smt/term_formula_removal.h b/src/smt/term_formula_removal.h
index 371ca1f58..63a74a332 100644
--- a/src/smt/term_formula_removal.h
+++ b/src/smt/term_formula_removal.h
@@ -37,11 +37,49 @@ namespace theory {
 typedef std::unordered_map<Node, unsigned, NodeHashFunction> IteSkolemMap;
 
 class RemoveTermFormulas {
-  typedef context::CDInsertHashMap< std::pair<Node, int>, Node, PairHashFunction<Node, int, NodeHashFunction, BoolHashFunction> > ITECache;
-  ITECache d_iteCache;
+  typedef context::
+      CDInsertHashMap<std::pair<Node, int>,
+                      Node,
+                      PairHashFunction<Node, int, NodeHashFunction> >
+          TermFormulaCache;
+  /** term formula removal cache
+   *
+   * This stores the results of term formula removal for inputs to the run(...)
+   * function below, where the integer in the pair we hash on is the
+   * result of cacheVal below.
+   */
+  TermFormulaCache d_tfCache;
 
+  /** return the integer cache value for the input flags to run(...) */
   static inline int cacheVal( bool inQuant, bool inTerm ) { return (inQuant ? 1 : 0) + 2*(inTerm ? 1 : 0); }
-  
+
+  /** skolem cache
+   *
+   * This is a cache that maps terms to the skolem we use to replace them.
+   *
+   * Notice that this cache is necessary in addition to d_tfCache, since
+   * we should use the same skolem to replace terms, regardless of the input
+   * arguments to run(...). For example:
+   *
+   * ite( G, a, b ) = c ^ forall x. P( ite( G, a, b ), x )
+   *
+   * should be processed to:
+   *
+   * k = c ^ forall x. P( k, x ) ^ ite( G, k=a, k=b )
+   *
+   * where notice
+   *   d_skolem_cache[ite( G, a, b )] = k, and
+   *   d_tfCache[<ite( G, a, b ),0>] = d_tfCache[<ite( G, a, b ),1>] = k.
+   */
+  context::CDInsertHashMap<Node, Node, NodeHashFunction> d_skolem_cache;
+
+  /** gets the skolem for node
+   *
+   * This returns the d_skolem_cache value for node, if it exists as a key
+   * in the above map, or the null node otherwise.
+   */
+  inline Node getSkolemForNode(Node node) const;
+
   static bool hasNestedTermChildren( TNode node );
 public:
 
@@ -111,9 +149,6 @@ public:
   /** Returns true if e contains a term ite. */
   bool containsTermITE(TNode e) const;
 
-  /** Returns the collected size of the caches. */
-  size_t collectedCacheSizes() const;
-
   /** Garbage collects non-context dependent data-structures. */
   void garbageCollect();
 
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