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https://github.com/Z3Prover/z3
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119 lines
3.2 KiB
C++
119 lines
3.2 KiB
C++
/*++
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Copyright (c) 2022 Microsoft Corporation
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Module Name:
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propagate_values.h
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Abstract:
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relatively cheap value propagation
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Author:
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Nikolaj Bjorner (nbjorner) 2022-11-24
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Notes:
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Incremental version of propagate_values_tactic
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--*/
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#include "params/tactic_params.hpp"
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#include "ast/ast_pp.h"
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#include "ast/ast_util.h"
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#include "ast/simplifiers/propagate_values.h"
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propagate_values::propagate_values(ast_manager& m, params_ref const& p, dependent_expr_state& fmls):
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dependent_expr_simplifier(m, fmls),
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m_rewriter(m),
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m_shared(m, true),
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m_subst(m, true, false) {
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m_rewriter.set_flat_and_or(false);
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updt_params(p);
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}
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void propagate_values::process_fml(unsigned i) {
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if (!m_subst.empty()) {
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auto [f, p, dep] = m_fmls[i]();
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expr_ref fml(m);
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proof_ref pr(m);
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m_rewriter(f, fml, pr);
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if (fml != f) {
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dep = m.mk_join(dep, m_rewriter.get_used_dependencies());
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m_fmls.update(i, dependent_expr(m, fml, mp(p, pr), dep));
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++m_stats.m_num_rewrites;
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}
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m_rewriter.reset_used_dependencies();
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}
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add_sub(m_fmls[i]);
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}
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void propagate_values::add_sub(dependent_expr const& de) {
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expr* x, * y;
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auto const& [f, p, dep] = de();
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if (m.is_not(f, x) && m_shared.is_shared(x))
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m_subst.insert(x, m.mk_false(), dep);
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if (m_shared.is_shared(f))
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m_subst.insert(f, m.mk_true(), dep);
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if (m.is_eq(f, x, y)) {
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if (m.is_value(x) && m_shared.is_shared(y))
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m_subst.insert(y, x, dep);
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else if (m.is_value(y) && m_shared.is_shared(x))
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m_subst.insert(x, y, dep);
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}
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};
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void propagate_values::reduce() {
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m_shared.reset();
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m_subst.reset();
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auto add_shared = [&]() {
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shared_occs_mark visited;
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m_shared.reset();
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for (unsigned i = 0; i < qtail(); ++i)
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m_shared(m_fmls[i].fml(), visited);
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};
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auto init_sub = [&]() {
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add_shared();
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m_subst.reset();
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m_rewriter.reset();
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m_rewriter.set_substitution(&m_subst);
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for (unsigned i = 0; i < qhead(); ++i)
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add_sub(m_fmls[i]);
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};
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unsigned rw = m_stats.m_num_rewrites + 1;
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for (unsigned r = 0; r < m_max_rounds && m.inc() && rw != m_stats.m_num_rewrites; ++r) {
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rw = m_stats.m_num_rewrites;
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init_sub();
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for (unsigned i : indices())
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process_fml(i);
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init_sub();
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for (unsigned i = qtail(); i-- > qhead() && m.inc() && !m_fmls.inconsistent();)
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process_fml(i);
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if (m_subst.empty())
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break;
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}
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m_rewriter.set_substitution(nullptr);
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m_rewriter.reset();
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m_subst.reset();
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m_shared.reset();
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}
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void propagate_values::collect_statistics(statistics& st) const {
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st.update("propagate-values-rewrites", m_stats.m_num_rewrites);
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}
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void propagate_values::updt_params(params_ref const& p) {
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tactic_params tp(p);
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m_max_rounds = p.get_uint("max_rounds", tp.propagate_values_max_rounds());
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m_rewriter.updt_params(p);
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}
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void propagate_values::collect_param_descrs(param_descrs& r) {
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th_rewriter::get_param_descrs(r);
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r.insert("max_rounds", CPK_UINT, "maximum number of rounds.", "4");
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}
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