Z3 sources

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

lib/elim_term_ite_tactic.cpp

@@ -0,0 +1,198 @@
+/*++
+Copyright (c) 2011 Microsoft Corporation
+
+Module Name:
+
+    elim_term_ite_tactic.cpp
+
+Abstract:
+
+    Eliminate term if-then-else by adding 
+    new fresh auxiliary variables.
+
+Author:
+
+    Leonardo (leonardo) 2011-12-29
+
+Notes:
+
+--*/
+#include"tactical.h"
+#include"defined_names.h"
+#include"rewriter_def.h"
+#include"filter_model_converter.h"
+#include"cooperate.h"
+
+class elim_term_ite_tactic : public tactic {
+
+    struct rw_cfg : public default_rewriter_cfg {
+        ast_manager &               m;
+        defined_names               m_defined_names;
+        ref<filter_model_converter> m_mc;
+        goal *                      m_goal;
+        unsigned long long          m_max_memory; // in bytes
+        bool                        m_produce_models;
+        unsigned                    m_num_fresh;
+
+        bool max_steps_exceeded(unsigned num_steps) const { 
+            cooperate("elim term ite");
+            if (memory::get_allocation_size() > m_max_memory)
+                throw tactic_exception(TACTIC_MAX_MEMORY_MSG);
+            return false;
+        }
+
+        br_status reduce_app(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
+            if (!m.is_term_ite(f))
+                return BR_FAILED;
+            expr_ref new_ite(m);
+            new_ite = m.mk_app(f, num, args);
+            
+            expr_ref new_def(m);
+            proof_ref new_def_pr(m);
+            app_ref _result(m);
+            if (m_defined_names.mk_name(new_ite, new_def, new_def_pr, _result, result_pr)) {
+                m_goal->assert_expr(new_def, new_def_pr, 0);
+                m_num_fresh++;
+                if (m_produce_models) {
+                    if (!m_mc)
+                        m_mc = alloc(filter_model_converter, m);
+                    m_mc->insert(_result->get_decl());
+                }
+            }
+            result = _result.get();
+            return BR_DONE;
+        }
+        
+        rw_cfg(ast_manager & _m, params_ref const & p):
+            m(_m),
+            m_defined_names(m, 0 /* don't use prefix */) {
+            updt_params(p);
+            m_goal      = 0;
+            m_num_fresh = 0;
+        }
+
+        void updt_params(params_ref const & p) {
+            m_max_memory     = megabytes_to_bytes(p.get_uint(":max-memory", UINT_MAX));
+        }
+    };
+    
+    struct rw : public rewriter_tpl<rw_cfg> {
+        rw_cfg m_cfg;
+        
+        rw(ast_manager & m, params_ref const & p):
+            rewriter_tpl<rw_cfg>(m, m.proofs_enabled(), m_cfg),
+            m_cfg(m, p) {
+        }
+    };
+
+    struct imp {
+        ast_manager & m;
+        rw            m_rw;
+        
+        imp(ast_manager & _m, params_ref const & p):
+            m(_m),
+            m_rw(m, p) {
+        }
+        
+        void set_cancel(bool f) {
+            m_rw.set_cancel(f);
+        }
+        
+        void updt_params(params_ref const & p) {
+            m_rw.cfg().updt_params(p);
+        }
+        
+        void operator()(goal_ref const & g, 
+                        goal_ref_buffer & result, 
+                        model_converter_ref & mc, 
+                        proof_converter_ref & pc,
+                        expr_dependency_ref & core) {
+            SASSERT(g->is_well_sorted());
+            mc = 0; pc = 0; core = 0;
+            tactic_report report("elim-term-ite", *g);
+            bool produce_proofs = g->proofs_enabled();
+            m_rw.cfg().m_produce_models = g->models_enabled();
+
+            m_rw.m_cfg.m_num_fresh = 0;
+            m_rw.m_cfg.m_goal = g.get();
+            expr_ref   new_curr(m);
+            proof_ref  new_pr(m);
+            unsigned   size = g->size();
+            for (unsigned idx = 0; idx < size; idx++) {
+                expr * curr = g->form(idx);
+                m_rw(curr, new_curr, new_pr);
+                if (produce_proofs) {
+                    proof * pr = g->pr(idx);
+                    new_pr     = m.mk_modus_ponens(pr, new_pr);
+                }
+                g->update(idx, new_curr, new_pr, g->dep(idx));
+            }
+            mc = m_rw.m_cfg.m_mc.get();
+            report_tactic_progress(":elim-term-ite-consts", m_rw.m_cfg.m_num_fresh);
+            g->inc_depth();
+            result.push_back(g.get());
+            TRACE("elim_term_ite", g->display(tout););
+            SASSERT(g->is_well_sorted());
+        }
+    };
+    
+    imp *      m_imp;
+    params_ref m_params;
+public:
+    elim_term_ite_tactic(ast_manager & m, params_ref const & p):
+        m_params(p) {
+        m_imp = alloc(imp, m, p);
+    }
+
+    virtual tactic * translate(ast_manager & m) {
+        return alloc(elim_term_ite_tactic, m, m_params);
+    }
+        
+    virtual ~elim_term_ite_tactic() {
+        dealloc(m_imp);
+    }
+
+    virtual void updt_params(params_ref const & p) {
+        m_params = p;
+        m_imp->m_rw.cfg().updt_params(p);
+    }
+
+    virtual void collect_param_descrs(param_descrs & r) {
+        insert_max_memory(r);
+        insert_max_steps(r);
+        r.insert(":max-args", CPK_UINT, 
+                 "(default: 128) maximum number of arguments (per application) that will be considered by the greedy (quadratic) heuristic.");
+    }
+    
+    virtual void operator()(goal_ref const & in, 
+                            goal_ref_buffer & result, 
+                            model_converter_ref & mc, 
+                            proof_converter_ref & pc,
+                            expr_dependency_ref & core) {
+        (*m_imp)(in, result, mc, pc, core);
+    }
+    
+    virtual void cleanup() {
+        ast_manager & m = m_imp->m;
+        imp * d = m_imp;
+        #pragma omp critical (tactic_cancel)
+        {
+            m_imp = 0;
+        }
+        dealloc(d);
+        d = alloc(imp, m, m_params);
+        #pragma omp critical (tactic_cancel)
+        {
+            m_imp = d;
+        }
+    }
+
+    virtual void set_cancel(bool f) {
+        if (m_imp)
+            m_imp->set_cancel(f);
+    }
+};
+
+tactic * mk_elim_term_ite_tactic(ast_manager & m, params_ref const & p) {
+    return clean(alloc(elim_term_ite_tactic, m, p));
+}