add hook to turn on xor solver

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/sat/sat_params.pyg

@@ -62,6 +62,7 @@ def_module_params('sat',
                           ('pb.resolve', SYMBOL, 'cardinality', 'resolution strategy for boolean algebra solver: cardinality, rounding'),
                           ('pb.lemma_format', SYMBOL, 'cardinality', 'generate either cardinality or pb lemmas'),
                           ('euf', BOOL, False, 'enable euf solver (this feature is preliminary and not ready for general consumption)'),
+			  ('enable_xor', BOOL, False, 'enable xor solver plugin in combination with pure SAT solving'),
                           ('ddfw_search', BOOL, False, 'use ddfw local search instead of CDCL'),
                           ('ddfw.init_clause_weight', UINT, 8, 'initial clause weight for DDFW local search'),
                           ('ddfw.use_reward_pct', UINT, 15, 'percentage to pick highest reward variable when it has reward 0'),

src/sat/smt/CMakeLists.txt

@@ -44,6 +44,7 @@ z3_add_component(sat_smt
     sat_th.cpp
     tseitin_theory_checker.cpp
     user_solver.cpp
+    xor_solver.cpp
   COMPONENT_DEPENDENCIES
     sat
     ast

src/sat/smt/xor_solver.cpp

@@ -19,9 +19,16 @@ Abstract:
 
 namespace xr {
 
+
     solver::solver(euf::solver& ctx):
-        th_solver(ctx.get_manager(), symbol("xor-solver"), ctx.get_manager().get_family_id("xor-solver"))
+        solver(ctx.get_manager(), ctx.get_si(), ctx.get_manager().get_family_id("xor")) {
-    {}
+        m_ctx = &ctx;
+    }
+
+    solver::solver(ast_manager& m, sat::sat_internalizer& si, euf::theory_id id)
+        : euf::th_solver(m, symbol("xor"), id),
+          si(si) {
+    }
 
     euf::th_solver* solver::clone(euf::solver& ctx) {
         // and relevant copy internal state

src/sat/smt/xor_solver.h

@@ -18,9 +18,11 @@ Abstract:
 
 namespace xr {
     class solver : public euf::th_solver {
+        euf::solver* m_ctx = nullptr;
+        sat::sat_internalizer& si;
     public:
         solver(euf::solver& ctx);
-        
+        solver(ast_manager& m, sat::sat_internalizer& si, euf::theory_id id);
         th_solver* clone(euf::solver& ctx) override;
 
         sat::literal internalize(expr* e, bool sign, bool root)  override { UNREACHABLE(); return sat::null_literal; }

src/sat/tactic/goal2sat.cpp

@@ -42,6 +42,7 @@ Notes:
 #include "sat/sat_drat.h"
 #include "sat/tactic/goal2sat.h"
 #include "sat/smt/pb_solver.h"
+#include "sat/smt/xor_solver.h"
 #include "sat/smt/euf_solver.h"
 #include "sat/smt/sat_th.h"
 #include "sat/sat_params.hpp"
@@ -75,6 +76,7 @@ struct goal2sat::imp : public sat::sat_internalizer {
     func_decl_ref_vector        m_unhandled_funs;
     bool                        m_default_external;
     bool                        m_euf = false;
+    bool                        m_xor = false;
     bool                        m_top_level = false;
     sat::literal_vector         aig_lits;
     
@@ -100,6 +102,7 @@ struct goal2sat::imp : public sat::sat_internalizer {
         m_ite_extra  = p.get_bool("ite_extra", true);
         m_max_memory = megabytes_to_bytes(p.get_uint("max_memory", UINT_MAX));
         m_euf = sp.euf();
+        m_xor = sp.enable_xor();
     }
 
     void throw_op_not_handled(std::string const& s) {
@@ -658,6 +661,14 @@ struct goal2sat::imp : public sat::sat_internalizer {
         return m_unhandled_funs;
     }
 
+    void ensure_xor() {
+        sat::extension* ext = m_solver.get_extension();
+        if (ext)
+            return;
+        auto* x = alloc(xr::solver, m, *this, m.get_family_id("xor"));
+        m_solver.set_extension(x);        
+    }
+
     euf::solver* ensure_euf() {
         SASSERT(m_euf);
         sat::extension* ext = m_solver.get_extension();
@@ -950,6 +961,8 @@ struct goal2sat::imp : public sat::sat_internalizer {
         expr_ref_vector  fmls(m);
         if (m_euf)
             ensure_euf();
+        else if (m_xor)
+            ensure_xor();
         for (unsigned idx = 0; idx < size; idx++) {
             f = g.form(idx);
             // Add assumptions.