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Z3 sources
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
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Leonardo de Moura
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211
lib/var_subst.cpp
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211
lib/var_subst.cpp
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/*++
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Copyright (c) 2007 Microsoft Corporation
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Module Name:
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var_subst.cpp
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Abstract:
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Variable substitution.
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Author:
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Leonardo (leonardo) 2008-01-10
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Notes:
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--*/
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#include"var_subst.h"
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#include"used_vars.h"
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#include"ast_ll_pp.h"
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#include"ast_pp.h"
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#include"ast_smt2_pp.h"
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#include"well_sorted.h"
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#include"for_each_expr.h"
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void var_subst::operator()(expr * n, unsigned num_args, expr * const * args, expr_ref & result) {
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SASSERT(is_well_sorted(result.m(), n));
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m_reducer.reset();
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if (m_std_order)
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m_reducer.set_inv_bindings(num_args, args);
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else
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m_reducer.set_bindings(num_args, args);
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m_reducer(n, result);
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SASSERT(is_well_sorted(m_reducer.m(), result));
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TRACE("var_subst_bug",
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tout << "m_std_order: " << m_std_order << "\n" << mk_ismt2_pp(n, m_reducer.m()) << "\nusing\n";
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for (unsigned i = 0; i < num_args; i++) tout << mk_ismt2_pp(args[i], m_reducer.m()) << "\n";
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tout << "\n------>\n";
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tout << mk_ismt2_pp(result, m_reducer.m()) << "\n";);
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}
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void elim_unused_vars(ast_manager & m, quantifier * q, expr_ref & result) {
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SASSERT(is_well_sorted(m, q));
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if (is_ground(q->get_expr())) {
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// ignore patterns if the body is a ground formula.
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result = q->get_expr();
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return;
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}
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if (!q->may_have_unused_vars()) {
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result = q;
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return;
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}
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used_vars used;
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used.process(q->get_expr());
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unsigned num_patterns = q->get_num_patterns();
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for (unsigned i = 0; i < num_patterns; i++)
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used.process(q->get_pattern(i));
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unsigned num_no_patterns = q->get_num_no_patterns();
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for (unsigned i = 0; i < num_no_patterns; i++)
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used.process(q->get_no_pattern(i));
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unsigned num_decls = q->get_num_decls();
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if (used.uses_all_vars(num_decls)) {
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q->set_no_unused_vars();
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result = q;
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return;
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}
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ptr_buffer<sort> used_decl_sorts;
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buffer<symbol> used_decl_names;
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for (unsigned i = 0; i < num_decls; ++i) {
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if (used.contains(num_decls - i - 1)) {
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used_decl_sorts.push_back(q->get_decl_sort(i));
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used_decl_names.push_back(q->get_decl_name(i));
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}
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}
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unsigned num_removed = 0;
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expr_ref_buffer var_mapping(m);
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int next_idx = 0;
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unsigned sz = used.get_max_found_var_idx_plus_1();
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for (unsigned i = 0; i < num_decls; ++i) {
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sort * s = used.contains(i);
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if (s) {
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var_mapping.push_back(m.mk_var(next_idx, s));
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next_idx++;
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}
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else {
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num_removed++;
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var_mapping.push_back(0);
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}
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}
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// (VAR 0) is in the first position of var_mapping.
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for (unsigned i = num_decls; i < sz; i++) {
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sort * s = used.contains(i);
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if (s)
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var_mapping.push_back(m.mk_var(i - num_removed, s));
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else
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var_mapping.push_back(0);
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}
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// Remark:
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// (VAR 0) should be in the last position of var_mapping.
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// ...
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// (VAR (var_mapping.size() - 1)) should be in the first position.
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std::reverse(var_mapping.c_ptr(), var_mapping.c_ptr() + var_mapping.size());
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expr_ref new_expr(m);
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var_subst subst(m);
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subst(q->get_expr(), var_mapping.size(), var_mapping.c_ptr(), new_expr);
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if (num_removed == num_decls) {
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result = new_expr;
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return;
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}
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expr_ref tmp(m);
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expr_ref_buffer new_patterns(m);
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expr_ref_buffer new_no_patterns(m);
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for (unsigned i = 0; i < num_patterns; i++) {
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subst(q->get_pattern(i), var_mapping.size(), var_mapping.c_ptr(), tmp);
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new_patterns.push_back(tmp);
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}
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for (unsigned i = 0; i < num_no_patterns; i++) {
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subst(q->get_no_pattern(i), var_mapping.size(), var_mapping.c_ptr(), tmp);
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new_no_patterns.push_back(tmp);
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}
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result = m.mk_quantifier(q->is_forall(),
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used_decl_sorts.size(),
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used_decl_sorts.c_ptr(),
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used_decl_names.c_ptr(),
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new_expr,
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q->get_weight(),
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q->get_qid(),
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q->get_skid(),
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num_patterns,
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new_patterns.c_ptr(),
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num_no_patterns,
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new_no_patterns.c_ptr());
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to_quantifier(result)->set_no_unused_vars();
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SASSERT(is_well_sorted(m, result));
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}
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void instantiate(ast_manager & m, quantifier * q, expr * const * exprs, expr_ref & result) {
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var_subst subst(m);
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expr_ref new_expr(m);
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subst(q->get_expr(), q->get_num_decls(), exprs, new_expr);
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TRACE("var_subst", tout << mk_pp(q, m) << "\n" << mk_pp(new_expr, m) << "\n";);
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inv_var_shifter shift(m);
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shift(new_expr, q->get_num_decls(), result);
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SASSERT(is_well_sorted(m, result));
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TRACE("instantiate_bug", tout << mk_ismt2_pp(q, m) << "\nusing\n";
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for (unsigned i = 0; i < q->get_num_decls(); i++) tout << mk_ismt2_pp(exprs[i], m) << "\n";
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tout << "\n----->\n" << mk_ismt2_pp(result, m) << "\n";);
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}
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static void get_free_vars_offset(expr* e, unsigned offset, ptr_vector<sort>& sorts) {
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ast_mark mark;
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ptr_vector<expr> todo;
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todo.push_back(e);
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while (!todo.empty()) {
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e = todo.back();
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todo.pop_back();
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if (mark.is_marked(e)) {
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continue;
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}
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mark.mark(e, true);
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switch(e->get_kind()) {
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case AST_QUANTIFIER: {
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quantifier* q = to_quantifier(e);
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get_free_vars_offset(q->get_expr(), offset+q->get_num_decls(), sorts);
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break;
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}
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case AST_VAR: {
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var* v = to_var(e);
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if (v->get_idx() >= offset) {
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unsigned idx = v->get_idx()-offset;
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if (sorts.size() <= idx) {
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sorts.resize(idx+1);
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}
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if (!sorts[idx]) {
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sorts[idx] = v->get_sort();
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}
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SASSERT(sorts[idx] == v->get_sort());
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}
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break;
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}
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case AST_APP: {
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app* a = to_app(e);
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for (unsigned i = 0; i < a->get_num_args(); ++i) {
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todo.push_back(a->get_arg(i));
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}
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break;
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}
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default:
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UNREACHABLE();
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}
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}
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}
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void get_free_vars(expr* e, ptr_vector<sort>& sorts) {
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get_free_vars_offset(e, 0, sorts);
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}
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