z3-z3-4.13.0.src.ast.rewriter.var_subst.cpp Maven / Gradle / Ivy
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/*++
Copyright (c) 2007 Microsoft Corporation
Module Name:
var_subst.cpp
Abstract:
Variable substitution.
Author:
Leonardo (leonardo) 2008-01-10
Notes:
--*/
#include "ast/rewriter/var_subst.h"
#include "ast/rewriter/expr_safe_replace.h"
#include "ast/ast_ll_pp.h"
#include "ast/ast_pp.h"
#include "ast/ast_smt2_pp.h"
#include "ast/well_sorted.h"
#include "ast/for_each_expr.h"
expr_ref var_subst::operator()(expr * n, unsigned num_args, expr * const * args) {
ast_manager& m = m_reducer.m();
expr_ref result(m);
if (is_ground(n) || num_args == 0) {
result = n;
//application does not have free variables or nested quantifiers.
//There is no need to print the bindings here?
SCTRACE("bindings", is_trace_enabled("coming_from_quant"),
tout << "(ground)\n";
for (unsigned i = 0; i < num_args; i++) {
if (args[i]) {
tout << i << ": " << mk_ismt2_pp(args[i], result.m()) << ";\n";
}
}
tout.flush(););
return result;
}
if (has_quantifiers(n)) {
expr_safe_replace rep(m);
for (unsigned k = 0; k < num_args; ++k) {
expr* arg = args[k];
if (arg)
rep.insert(m.mk_var(m_std_order ? num_args - k - 1 : k, arg->get_sort()), arg);
}
rep(n, result);
return result;
}
SASSERT(is_well_sorted(result.m(), n));
m_reducer.reset();
if (m_std_order)
m_reducer.set_inv_bindings(num_args, args);
else
m_reducer.set_bindings(num_args, args);
m_reducer(n, result);
SASSERT(is_well_sorted(m, result));
TRACE("var_subst_bug",
tout << "m_std_order: " << m_std_order << "\n" << mk_ismt2_pp(n, m) << "\nusing\n";
for (unsigned i = 0; i < num_args; i++) tout << mk_ismt2_pp(args[i], m) << "\n";
tout << "\n------>\n";
tout << result << "\n";);
return result;
}
unused_vars_eliminator::unused_vars_eliminator(ast_manager & m, params_ref const & params) :
m(m), m_subst(m), m_params(params)
{
m_ignore_patterns_on_ground_qbody = m_params.get_bool("ignore_patterns_on_ground_qbody", true);
}
expr_ref unused_vars_eliminator::operator()(quantifier* q) {
expr_ref result(m);
SASSERT(is_well_sorted(m, q));
TRACE("elim_unused_vars", tout << expr_ref(q, m) << "\n";);
if (is_lambda(q)) {
result = q;
return result;
}
if (m_ignore_patterns_on_ground_qbody && is_ground(q->get_expr())) {
// Ignore patterns if the body is a ground formula.
result = q->get_expr();
return result;
}
if (!q->may_have_unused_vars()) {
result = q;
return result;
}
unsigned num_decls = q->get_num_decls();
m_used.reset();
m_used.set_num_decls(num_decls);
m_used.process(q->get_expr());
unsigned num_patterns = q->get_num_patterns();
for (unsigned i = 0; i < num_patterns; i++)
m_used.process(q->get_pattern(i));
unsigned num_no_patterns = q->get_num_no_patterns();
for (unsigned i = 0; i < num_no_patterns; i++)
m_used.process(q->get_no_pattern(i));
if (m_used.uses_all_vars(num_decls)) {
q->set_no_unused_vars();
result = q;
return result;
}
ptr_buffer used_decl_sorts;
buffer used_decl_names;
for (unsigned i = 0; i < num_decls; ++i) {
if (m_used.contains(num_decls - i - 1)) {
used_decl_sorts.push_back(q->get_decl_sort(i));
used_decl_names.push_back(q->get_decl_name(i));
}
}
unsigned num_removed = 0;
expr_ref_buffer var_mapping(m);
int next_idx = 0;
unsigned sz = m_used.get_max_found_var_idx_plus_1();
for (unsigned i = 0; i < num_decls; ++i) {
sort * s = m_used.contains(i);
if (s) {
var_mapping.push_back(m.mk_var(next_idx, s));
next_idx++;
}
else {
num_removed++;
var_mapping.push_back(nullptr);
}
}
// (VAR 0) is in the first position of var_mapping.
for (unsigned i = num_decls; i < sz; i++) {
sort * s = m_used.contains(i);
if (s)
var_mapping.push_back(m.mk_var(i - num_removed, s));
else
var_mapping.push_back(nullptr);
}
// Remark:
// (VAR 0) should be in the last position of var_mapping.
// ...
// (VAR (var_mapping.size() - 1)) should be in the first position.
std::reverse(var_mapping.data(), var_mapping.data() + var_mapping.size());
expr_ref new_expr(m);
new_expr = m_subst(q->get_expr(), var_mapping.size(), var_mapping.data());
if (num_removed == num_decls) {
result = new_expr;
return result;
}
expr_ref_buffer new_patterns(m);
expr_ref_buffer new_no_patterns(m);
for (unsigned i = 0; i < num_patterns; i++) {
new_patterns.push_back(m_subst(q->get_pattern(i), var_mapping.size(), var_mapping.data()));
}
for (unsigned i = 0; i < num_no_patterns; i++) {
new_no_patterns.push_back(m_subst(q->get_no_pattern(i), var_mapping.size(), var_mapping.data()));
}
result = m.mk_quantifier(q->get_kind(),
used_decl_sorts.size(),
used_decl_sorts.data(),
used_decl_names.data(),
new_expr,
q->get_weight(),
q->get_qid(),
q->get_skid(),
num_patterns,
new_patterns.data(),
num_no_patterns,
new_no_patterns.data());
to_quantifier(result)->set_no_unused_vars();
SASSERT(is_well_sorted(m, result));
return result;
}
expr_ref elim_unused_vars(ast_manager & m, quantifier * q, params_ref const & params) {
unused_vars_eliminator el(m, params);
expr_ref result = el(q);
TRACE("elim_unused_vars", tout << expr_ref(q, m) << " -> " << result << "\n";);
return result;
}
expr_ref instantiate(ast_manager & m, quantifier * q, expr * const * exprs) {
var_subst subst(m);
expr_ref new_expr(m), result(m);
new_expr = subst(q->get_expr(), q->get_num_decls(), exprs);
TRACE("var_subst", tout << mk_pp(q, m) << "\n" << new_expr << "\n";);
inv_var_shifter shift(m);
shift(new_expr, q->get_num_decls(), result);
SASSERT(is_well_sorted(m, result));
TRACE("instantiate_bug", tout << mk_ismt2_pp(q, m) << "\nusing\n";
for (unsigned i = 0; i < q->get_num_decls(); i++) tout << mk_ismt2_pp(exprs[i], m) << "\n";
tout << "\n----->\n" << mk_ismt2_pp(result, m) << "\n";);
return result;
}
static void get_free_vars_offset(expr_sparse_mark& mark, ptr_vector& todo, unsigned offset, expr* e, ptr_vector& sorts) {
todo.push_back(e);
while (!todo.empty()) {
e = todo.back();
todo.pop_back();
if (mark.is_marked(e)) {
continue;
}
mark.mark(e, true);
switch(e->get_kind()) {
case AST_QUANTIFIER: {
quantifier* q = to_quantifier(e);
expr_sparse_mark mark1;
ptr_vector todo1;
get_free_vars_offset(mark1, todo1, offset+q->get_num_decls(), q->get_expr(), sorts);
break;
}
case AST_VAR: {
var* v = to_var(e);
if (v->get_idx() >= offset) {
unsigned idx = v->get_idx()-offset;
if (sorts.size() <= idx) {
sorts.resize(idx+1);
}
if (!sorts[idx]) {
sorts[idx] = v->get_sort();
}
SASSERT(sorts[idx] == v->get_sort());
}
break;
}
case AST_APP: {
for (expr* arg : *to_app(e))
todo.push_back(arg);
break;
}
default:
UNREACHABLE();
}
}
}
void get_free_vars(expr* e, ptr_vector& sorts) {
expr_sparse_mark mark;
ptr_vector todo;
get_free_vars_offset(mark, todo, 0, e, sorts);
}
void get_free_vars(expr_sparse_mark& mark, ptr_vector& todo, expr* e, ptr_vector& sorts) {
get_free_vars_offset(mark, todo, 0, e, sorts);
}
void expr_free_vars::reset() {
m_mark.reset();
m_sorts.reset();
SASSERT(m_todo.empty());
}
void expr_free_vars::set_default_sort(sort *s) {
for (unsigned i = 0; i < m_sorts.size(); ++i) {
if (!m_sorts[i]) m_sorts[i] = s;
}
}
void expr_free_vars::operator()(expr* e) {
reset();
get_free_vars_offset(m_mark, m_todo, 0, e, m_sorts);
}
void expr_free_vars::accumulate(expr* e) {
SASSERT(m_todo.empty());
get_free_vars_offset(m_mark, m_todo, 0, e, m_sorts);
}