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https://github.com/Z3Prover/z3
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3433b14dfa
- range and fixed restrictions on terms are based on constraints and can be violated temporarily. - bv_eval currently does not allow updating over fixed bits which leads to non-termination. TODO - lookahead only considers tabu when setting values of variables.
138 lines
3.9 KiB
C++
138 lines
3.9 KiB
C++
/*++
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Copyright (c) 2024 Microsoft Corporation
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Module Name:
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sls_bv_lookahead.h
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Abstract:
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Lookahead solver for BV, modeled after sls_engine/sls_tracker/sls_evaluator.
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Author:
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Nikolaj Bjorner (nbjorner) 2024-12-26
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--*/
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#pragma once
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#include "ast/bv_decl_plugin.h"
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#include "ast/sls/sls_context.h"
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#include "ast/sls/sls_bv_valuation.h"
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namespace sls {
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class bv_eval;
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class bv_lookahead {
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struct config {
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double cb = 2.85;
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unsigned paws_init = 40;
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unsigned paws_sp = 52;
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bool paws = true;
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bool walksat = true;
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bool walksat_repick = false;
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unsigned wp = 100;
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unsigned restart_base = 1000;
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unsigned restart_next = 1000;
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unsigned restart_init = 1000;
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bool early_prune = true;
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unsigned max_moves = 0;
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unsigned max_moves_base = 800;
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unsigned propagation_base = 10000;
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bool ucb = true;
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double ucb_constant = 1.0;
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double ucb_forget = 0.1;
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bool ucb_init = false;
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double ucb_noise = 0.1;
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};
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struct stats {
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unsigned m_num_lookahead = 0;
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unsigned m_num_updates = 0;
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unsigned m_moves = 0;
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unsigned m_restarts = 0;
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unsigned m_num_propagations = 0;
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};
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struct bool_info {
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unsigned weight = 40;
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double score = 0;
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unsigned touched = 1;
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};
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bv_util bv;
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bv_eval& m_ev;
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context& ctx;
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ast_manager& m;
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config m_config;
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stats m_stats;
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bvect m_v_saved, m_v_updated;
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ptr_vector<expr> m_restore;
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vector<ptr_vector<app>> m_update_stack;
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expr_mark m_on_restore, m_in_update_stack;
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double m_best_score = 0, m_top_score = 0;
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bvect m_best_value;
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expr* m_best_expr = nullptr;
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ptr_vector<expr> m_empty_vars;
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obj_map<expr, bool_info> m_bool_info;
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expr_mark m_is_root;
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unsigned m_touched = 1;
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std::ostream& display_weights(std::ostream& out);
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bv_valuation& wval(expr* e) const;
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void insert_update_stack(expr* e);
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void insert_update(expr* e);
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void restore_lookahead();
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bool_info& get_bool_info(expr* e);
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double lookahead_update(expr* u, bvect const& new_value);
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double old_score(app* c) { return get_bool_info(c).score; }
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void set_score(app* c, double d) { get_bool_info(c).score = d; }
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double new_score(app* c);
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void rescore();
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unsigned get_weight(expr* e) { return get_bool_info(e).weight; }
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void inc_weight(expr* e) { ++get_bool_info(e).weight; }
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void dec_weight(expr* e);
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void recalibrate_weights();
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bool is_root(expr* e) { return m_is_root.is_marked(e); }
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void ucb_forget();
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unsigned get_touched(app* e) { return get_bool_info(e).touched; }
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void set_touched(app* e, unsigned t) { get_bool_info(e).touched = t; }
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void inc_touched(app* e) { ++get_bool_info(e).touched; }
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void try_set(expr* u, bvect const& new_value);
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void add_updates(expr* u);
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bool apply_update(expr* e, bvect const& new_value, char const* reason);
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bool apply_random_move(ptr_vector<expr> const& vars);
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bool apply_guided_move(ptr_vector<expr> const& vars);
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bool apply_random_update(ptr_vector<expr> const& vars);
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ptr_vector<expr> const& get_candidate_uninterp();
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void check_restart();
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void reset_uninterp_in_false_literals();
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bool is_bv_literal(sat::literal lit);
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bool is_false_bv_literal(sat::literal lit);
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void search();
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public:
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bv_lookahead(bv_eval& ev);
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void updt_params(params_ref const& p);
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void start_propagation();
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bool on_restore(expr* e) const;
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void collect_statistics(statistics& st) const;
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};
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} |