Spacer engine for HORN logic

The algorithms implemented in the engine are described in the following papers

Anvesh Komuravelli, Nikolaj Bjørner, Arie Gurfinkel, Kenneth L. McMillan:
Compositional Verification of Procedural Programs using Horn Clauses over Integers and Arrays. FMCAD 2015: 89-96

Nikolaj Bjørner, Arie Gurfinkel:
Property Directed Polyhedral Abstraction. VMCAI 2015: 263-281

Anvesh Komuravelli, Arie Gurfinkel, Sagar Chaki:
SMT-Based Model Checking for Recursive Programs. CAV 2014: 17-34

src/muz/spacer/spacer_itp_solver.h

@@ -0,0 +1,177 @@
+/**
+Copyright (c) 2017 Arie Gurfinkel
+
+Module Name:
+
+    spacer_itp_solver.h
+
+Abstract:
+
+   A solver that produces interpolated unsat cores
+
+Author:
+
+    Arie Gurfinkel
+
+Notes:
+
+--*/
+#ifndef SPACER_ITP_SOLVER_H_
+#define SPACER_ITP_SOLVER_H_
+
+#include "solver.h"
+#include "expr_substitution.h"
+#include"stopwatch.h"
+namespace spacer {
+class itp_solver : public solver {
+private:
+    struct def_manager {
+        itp_solver &m_parent;
+        obj_map<expr, app*> m_expr2proxy;
+        obj_map<app, app*> m_proxy2def;
+
+        expr_ref_vector m_defs;
+
+        def_manager(itp_solver &parent) :
+            m_parent(parent), m_defs(m_parent.m)
+        {}
+
+        bool is_proxy(app *k, app_ref &v);
+        app* mk_proxy(expr *v);
+        void reset();
+        bool is_proxy_def(expr *v);
+
+    };
+
+    friend struct def_manager;
+    ast_manager &m;
+    solver &m_solver;
+    app_ref_vector m_proxies;
+    unsigned m_num_proxies;
+    vector<def_manager> m_defs;
+    def_manager m_base_defs;
+    expr_ref_vector m_assumptions;
+    unsigned m_first_assumption;
+    bool m_is_proxied;
+
+    stopwatch m_itp_watch;
+
+    expr_substitution m_elim_proxies_sub;
+    bool m_split_literals;
+    bool m_new_unsat_core;
+    bool m_minimize_unsat_core;
+    bool m_farkas_optimized;
+    bool m_farkas_a_const;
+
+    bool is_proxy(expr *e, app_ref &def);
+    void undo_proxies_in_core(ptr_vector<expr> &v);
+    app* mk_proxy(expr *v);
+    app* fresh_proxy();
+    void elim_proxies(expr_ref_vector &v);
+public:
+    itp_solver(solver &solver, bool new_unsat_core, bool minimize_unsat_core, bool farkas_optimized, bool farkas_a_const, bool split_literals = false) :
+        m(solver.get_manager()),
+        m_solver(solver),
+        m_proxies(m),
+        m_num_proxies(0),
+        m_base_defs(*this),
+        m_assumptions(m),
+        m_first_assumption(0),
+        m_is_proxied(false),
+        m_elim_proxies_sub(m, false, true),
+        m_split_literals(split_literals),
+        m_new_unsat_core(new_unsat_core),
+        m_minimize_unsat_core(minimize_unsat_core),
+        m_farkas_optimized(farkas_optimized),
+        m_farkas_a_const(farkas_a_const)
+    {}
+
+    virtual ~itp_solver() {}
+
+    /* itp solver specific */
+    virtual void get_unsat_core(expr_ref_vector &core);
+    virtual void get_itp_core(expr_ref_vector &core);
+    void set_split_literals(bool v) {m_split_literals = v;}
+    bool mk_proxies(expr_ref_vector &v, unsigned from = 0);
+    void undo_proxies(expr_ref_vector &v);
+
+    void push_bg(expr *e);
+    void pop_bg(unsigned n);
+    unsigned get_num_bg();
+
+    void get_full_unsat_core(ptr_vector<expr> &core)
+    {m_solver.get_unsat_core(core);}
+
+    /* solver interface */
+
+    virtual solver* translate(ast_manager &m, params_ref const &p)
+    {return m_solver.translate(m, p);}
+    virtual void updt_params(params_ref const &p)
+    {m_solver.updt_params(p);}
+    virtual void collect_param_descrs(param_descrs &r)
+    {m_solver.collect_param_descrs(r);}
+    virtual void set_produce_models(bool f)
+    {m_solver.set_produce_models(f);}
+    virtual void assert_expr(expr *t)
+    {m_solver.assert_expr(t);}
+
+    virtual void assert_expr(expr *t, expr *a)
+    {NOT_IMPLEMENTED_YET();}
+
+    virtual void push();
+    virtual void pop(unsigned n);
+    virtual unsigned get_scope_level() const
+    {return m_solver.get_scope_level();}
+
+    virtual lbool check_sat(unsigned num_assumptions, expr * const *assumptions);
+    virtual void set_progress_callback(progress_callback *callback)
+    {m_solver.set_progress_callback(callback);}
+    virtual unsigned get_num_assertions() const
+    {return m_solver.get_num_assertions();}
+    virtual expr * get_assertion(unsigned idx) const
+    {return m_solver.get_assertion(idx);}
+    virtual unsigned get_num_assumptions() const
+    {return m_solver.get_num_assumptions();}
+    virtual expr * get_assumption(unsigned idx) const
+    {return m_solver.get_assumption(idx);}
+    virtual std::ostream &display(std::ostream &out) const
+    {m_solver.display(out); return out;}
+
+    /* check_sat_result interface */
+
+    virtual void collect_statistics(statistics &st) const ;
+    virtual void reset_statistics();
+    virtual void get_unsat_core(ptr_vector<expr> &r);
+    virtual void get_model(model_ref &m) {m_solver.get_model(m);}
+    virtual proof *get_proof() {return m_solver.get_proof();}
+    virtual std::string reason_unknown() const
+    {return m_solver.reason_unknown();}
+    virtual void set_reason_unknown(char const* msg)
+    {m_solver.set_reason_unknown(msg);}
+    virtual void get_labels(svector<symbol> &r)
+    {m_solver.get_labels(r);}
+    virtual ast_manager &get_manager() const {return m;}
+
+    virtual void refresh();
+
+    class scoped_mk_proxy {
+        itp_solver &m_s;
+        expr_ref_vector &m_v;
+    public:
+        scoped_mk_proxy(itp_solver &s, expr_ref_vector &v) : m_s(s), m_v(v)
+        {m_s.mk_proxies(m_v);}
+        ~scoped_mk_proxy()
+        {m_s.undo_proxies(m_v);}
+    };
+
+    class scoped_bg {
+        itp_solver &m_s;
+        unsigned m_bg_sz;
+    public:
+        scoped_bg(itp_solver &s) : m_s(s), m_bg_sz(m_s.get_num_bg()) {}
+        ~scoped_bg()
+        {if(m_s.get_num_bg() > m_bg_sz) { m_s.pop_bg(m_s.get_num_bg() - m_bg_sz); }}
+    };
+};
+}
+#endif