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resolve

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-12-26 02:30:12 -08:00
parent d13f1310a7
commit 2c6e6b1fdb
4 changed files with 75 additions and 9 deletions
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24
src/math/dd/dd_pdd.cpp
View file

@ -461,6 +461,30 @@ namespace dd {
return is_binary(p.root);
}
/*
\brief determine if v occurs as a leaf variable.
*/
bool pdd_manager::var_is_leaf(PDD p, unsigned v) {
init_mark();
m_todo.push_back(p);
while (!m_todo.empty()) {
PDD r = m_todo.back();
m_todo.pop_back();
if (is_val(r) || is_marked(r)) continue;
set_mark(r);
if (var(r) == v) {
if (!is_val(lo(r)) || !is_val(hi(r))) {
m_todo.reset();
return false;
}
continue;
}
if (!is_marked(lo(r))) m_todo.push_back(lo(r));
if (!is_marked(hi(r))) m_todo.push_back(hi(r));
}
return true;
}
void pdd_manager::push(PDD b) {
m_pdd_stack.push_back(b);
}

8
src/math/dd/dd_pdd.h
View file

@ -203,6 +203,8 @@ namespace dd {
unsigned dag_size(pdd const& p);
unsigned degree(pdd const& p);
bool var_is_leaf(PDD p, unsigned v);
bool is_reachable(PDD p);
void compute_reachable(svector<bool>& reachable);
void try_gc();
@ -291,9 +293,9 @@ namespace dd {
bool is_zero() const { return m.is_zero(root); }
bool is_linear() const { return m.is_linear(root); }
bool is_binary() const { return m.is_binary(root); }
bool var_is_leaf(unsigned v) const { return m.var_is_leaf(root, v); }
pdd minus() const { return m.minus(*this); }
pdd operator-() const { return m.minus(*this); }
pdd operator+(pdd const& other) const { return m.add(*this, other); }
pdd operator-(pdd const& other) const { return m.sub(*this, other); }
pdd operator*(pdd const& other) const { return m.mul(*this, other); }
@ -317,11 +319,11 @@ namespace dd {
inline pdd operator*(int x, pdd const& b) { return b * rational(x); }
inline pdd operator*(pdd const& b, int x) { return b * rational(x); }
inline pdd operator+(rational const& r, const pdd& b) { return b + r; }
inline pdd operator+(rational const& r, pdd const& b) { return b + r; }
inline pdd operator+(int x, pdd const& b) { return b + rational(x); }
inline pdd operator+(pdd const& b, int x) { return b + rational(x); }
inline pdd operator-(rational const& r, pdd const& b) { return r + (-b); }
inline pdd operator-(rational const& r, pdd const& b) { return r + b.minus(); }
inline pdd operator-(int x, pdd const& b) { return rational(x) - b; }
inline pdd operator-(pdd const& b, int x) { return b + (-rational(x)); }

51
src/math/grobner/pdd_grobner.cpp
View file

@ -189,7 +189,8 @@ namespace dd {
while (simplify_linear_step(true) ||
simplify_elim_pure_step() ||
simplify_linear_step(false) ||
simplify_cc_step() ||
simplify_cc_step() ||
simplify_leaf_step() ||
/*simplify_elim_dual_step() ||*/
false) {
DEBUG_CODE(invariant(););
@ -304,6 +305,43 @@ namespace dd {
return reduced;
}
/**
\brief remove ax+b from p if x occurs as a leaf in p and a is a constant.
*/
bool grobner::simplify_leaf_step() {
use_list_t use_list = get_use_list();
bool reduced = false;
equation_vector leaves;
for (unsigned i = 0; i < m_to_simplify.size(); ++i) {
equation* e = m_to_simplify[i];
pdd p = e->poly();
if (!p.hi().is_val()) {
continue;
}
leaves.reset();
for (equation* e2 : use_list[p.var()]) {
if (e != e2 && e2->poly().var_is_leaf(p.var())) {
leaves.push_back(e2);
}
}
for (equation* e2 : leaves) {
bool changed_leading_term;
remove_from_use(e2, use_list);
simplify_using(*e2, *e, changed_leading_term);
add_to_use(e2, use_list);
if (check_conflict(*e2)) {
return false;
}
else if (changed_leading_term) {
pop_equation(e2);
push_equation(to_simplify, e2);
}
reduced = true;
}
}
return reduced;
}
/**
\brief treat equations as processed if top variable occurs only once.
*/
@ -334,12 +372,13 @@ namespace dd {
bool grobner::simplify_elim_dual_step() {
use_list_t use_list = get_use_list();
unsigned j = 0;
bool reduced = false;
for (unsigned i = 0; i < m_to_simplify.size(); ++i) {
equation* e = m_to_simplify[i];
pdd p = e->poly();
// check that e is linear in top variable.
if (e->state() != to_simplify) {
// this was moved before this pass
reduced = true;
}
else if (!done() && !is_trivial(*e) && p.hi().is_val() && use_list[p.var()].size() == 2) {
for (equation* e2 : use_list[p.var()]) {
@ -351,9 +390,8 @@ namespace dd {
if (check_conflict(*e2)) {
break;
}
if (is_trivial(*e2)) {
break;
}
// when e2 is trivial, leading term is changed
SASSERT(!is_trivial(*e2) || changed_leading_term);
if (changed_leading_term) {
pop_equation(e2);
push_equation(to_simplify, e2);
@ -361,6 +399,7 @@ namespace dd {
add_to_use(e2, use_list);
break;
}
reduced = true;
push_equation(solved, e);
}
else {
@ -368,7 +407,7 @@ namespace dd {
e->set_index(j++);
}
}
if (j != m_to_simplify.size()) {
if (reduced) {
// clean up elements in m_to_simplify
// they may have moved.
m_to_simplify.shrink(j);

1
src/math/grobner/pdd_grobner.h
View file

@ -170,6 +170,7 @@ private:
bool simplify_cc_step();
bool simplify_elim_pure_step();
bool simplify_elim_dual_step();
bool simplify_leaf_step();
void invariant() const;
struct scoped_process {