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Improve factor equalities

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This commit is contained in:
Arie Gurfinkel 2017-11-22 18:29:08 -05:00
parent 5a37518e58
commit 6818eb3340
2 changed files with 52 additions and 10 deletions
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55
src/ast/factor_equivs.cpp
View file

@ -27,7 +27,9 @@ Revision History:
#include "ast/factor_equivs.h"
#include "ast/arith_decl_plugin.h"
#include "ast/for_each_expr.h"
#include "ast/ast_pp.h"
#include "ast/rewriter/expr_safe_replace.h"
/**
Factors input vector v into equivalence classes and the rest
*/
@ -59,8 +61,8 @@ void factor_eqs(expr_ref_vector &v, expr_equiv_class &equiv) {
equiv.merge(e1, e2);
}
else {
if (j < i) {
v[j] = v.get(i);
if (j < i) {
v[j] = v.get(i);
}
j++;
}
@ -68,19 +70,52 @@ void factor_eqs(expr_ref_vector &v, expr_equiv_class &equiv) {
v.shrink(j);
}
/**
* Chooses a representative of an equivalence class
*/
expr *choose_rep(expr_equiv_class::eq_class &clazz, ast_manager &m) {
expr *rep = nullptr;
unsigned rep_sz, elem_sz;
for (expr *elem : clazz) {
if (!m.is_value(elem)) {
elem_sz = get_num_exprs(elem);
if (!rep || (rep && rep_sz > elem_sz)) {
rep = elem;
rep_sz = elem_sz;
}
}
}
TRACE("equiv",
tout << "Rep: " << mk_pp(rep, m) << "\n";
for (expr *el : clazz)
tout << mk_pp(el, m) << "\n";
tout << "RepEnd\n";);
return rep;
}
void rewrite_eqs (expr_ref_vector &v, expr_equiv_class &equiv) {
ast_manager &m = v.m();
expr_safe_replace sub(m);
for (auto eq_class : equiv) {
expr *rep = choose_rep(eq_class, m);
for (expr *el : eq_class) {
if (el != rep) {
sub.insert (el, rep);
}
}
}
sub(v);
}
/**
* converts equivalence classes to equalities
*/
void equiv_to_expr(expr_equiv_class &equiv, expr_ref_vector &out) {
ast_manager &m = out.get_manager();
for (auto eq_class : equiv) {
expr *rep = nullptr;
for (expr *elem : eq_class) {
if (!m.is_value(elem)) {
rep = elem;
break;
}
}
expr *rep = choose_rep(eq_class, m);
SASSERT(rep);
for (expr *elem : eq_class) {
if (rep != elem) {

7
src/ast/factor_equivs.h
View file

@ -60,6 +60,8 @@ public:
obj_equiv_class(Manager& m) : m_to_obj(m) {}
Manager &m() const {return m_to_obj.m();}
void add_elem(OBJ*o) {
SASSERT(!m_to_int.find(o));
add_elem_impl(o);
@ -169,6 +171,11 @@ typedef obj_equiv_class<expr, ast_manager> expr_equiv_class;
* Factors input vector v into equivalence classes and the rest
*/
void factor_eqs(expr_ref_vector &v, expr_equiv_class &equiv);
/**
* Rewrite expressions in v by choosing a representative from the
* equivalence class.
*/
void rewrite_eqs(expr_ref_vector &v, expr_equiv_class &equiv);
/**
* converts equivalence classes to equalities
*/