Cadical with preprocessor and local search

This adds the option to enable Cadical's preprocessor and local search.  The
default remains unchanged.

The choice of preprocessor=1 and localsearch=0 for
satcheck_cadical_preprocessingt is motivated by the following data on the
HWMCC 2008 benchmarks:

0, 0: ./hwmcc08.sh  114.78s
1, 0: ./hwmcc08.sh  107.44s
2, 0: ./hwmcc08.sh  117.63s
5, 0: ./hwmcc08.sh  129.10s
1, 1: ./hwmcc08.sh  113.50s
5, 5: ./hwmcc08.sh  154.71s

Author: kroening

src/solvers/sat/satcheck.h

@@ -137,8 +137,8 @@ typedef satcheck_glucose_no_simplifiert satcheck_no_simplifiert;
 
 #elif defined SATCHECK_CADICAL
 
-typedef satcheck_cadicalt satcheckt;
-typedef satcheck_cadicalt satcheck_no_simplifiert;
+typedef satcheck_cadical_no_preprocessingt satcheckt;
+typedef satcheck_cadical_no_preprocessingt satcheck_no_simplifiert;
 
 #endif
 

src/solvers/sat/satcheck_cadical.cpp

@@ -108,6 +108,12 @@ propt::resultt satcheck_cadicalt::do_prop_solve(const bvt &assumptions)
     if(!a.is_true())
       solver->assume(a.dimacs());
 
+  // set preprocessing and inprocessing limits
+  auto limit1_ret = solver->limit("preprocessing", preprocessing_limit);
+  CHECK_RETURN(limit1_ret);
+  auto limit2_ret = solver->limit("localsearch", localsearch_limit);
+  CHECK_RETURN(limit2_ret);
+
   switch(solver->solve())
   {
   case 10:
@@ -134,8 +140,14 @@ void satcheck_cadicalt::set_assignment(literalt a, bool value)
   INVARIANT(false, "method not supported");
 }
 
-satcheck_cadicalt::satcheck_cadicalt(message_handlert &message_handler)
-  : cnf_solvert(message_handler), solver(new CaDiCaL::Solver())
+satcheck_cadicalt::satcheck_cadicalt(
+  int _preprocessing_limit,
+  int _localsearch_limit,
+  message_handlert &message_handler)
+  : cnf_solvert(message_handler),
+    solver(new CaDiCaL::Solver()),
+    preprocessing_limit(_preprocessing_limit),
+    localsearch_limit(_localsearch_limit)
 {
   solver->set("quiet", 1);
 }

src/solvers/sat/satcheck_cadical.h

@@ -19,10 +19,13 @@ namespace CaDiCaL // NOLINT(readability/namespace)
   class Solver; // NOLINT(readability/identifiers)
 }
 
-class satcheck_cadicalt : public cnf_solvert, public hardness_collectort
+class satcheck_cadical_baset : public cnf_solvert, public hardness_collectort
 {
 public:
-  explicit satcheck_cadicalt(message_handlert &message_handler);
+  satcheck_cadicalt(
+    int preprocessing_limit,
+    int localsearch_limit,
+    message_handlert &);
   virtual ~satcheck_cadicalt();
 
   std::string solver_text() const override;
@@ -46,6 +49,25 @@ class satcheck_cadicalt : public cnf_solvert, public hardness_collectort
 
   // NOLINTNEXTLINE(readability/identifiers)
   CaDiCaL::Solver *solver;
+  int preprocessing_limit = 0, localsearch_limit = 0;
+};
+
+class satcheck_cadical_no_preprocessingt : public satcheck_cadical_baset
+{
+public:
+  explicit satcheck_cadicalt(message_handlert &message_handler)
+    : satcheck_cadical_baset(0, 0, message_handler)
+  {
+  }
+};
+
+class satcheck_cadical_preprocessingt : public satcheck_cadical_baset
+{
+public:
+  explicit satcheck_cadicalt(message_handlert &message_handler)
+    : satcheck_cadical_baset(1, 0, message_handler)
+  {
+  }
 };
 
 #endif // CPROVER_SOLVERS_SAT_SATCHECK_CADICAL_H