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linear solver

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-05-14 17:10:01 -07:00
parent 17fcf79c04
commit 683ce27c8f
8 changed files with 264 additions and 42 deletions
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34
src/math/polysat/solver.cpp
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@ -153,13 +153,14 @@ namespace polysat {
m_free_vars.del_var_eh(v);
}
void solver::new_constraint(constraint* c) {
bool_var solver::new_constraint(constraint* c) {
SASSERT(c);
LOG("New constraint: " << *c);
m_linear_solver.new_constraint(*c);
m_constraints.push_back(c);
SASSERT(!get_bv2c(c->bvar()));
insert_bv2c(c->bvar(), c);
return c->bvar();
}
bool_var solver::new_eq(pdd const& p, unsigned dep) {
@ -184,35 +185,17 @@ namespace polysat {
auto non_zero = sz2bits(sz).non_zero();
p_dependency_ref d(mk_dep(dep), m_dm);
constraint* c = constraint::viable(m_level, m_next_bvar++, pos_t, slack, non_zero, d);
new_constraint(c);
return c->bvar();
return new_constraint(c);
}
bool_var solver::new_ule(pdd const& p, pdd const& q, unsigned dep, csign_t sign) {
p_dependency_ref d(mk_dep(dep), m_dm);
constraint* c = constraint::ule(m_level, m_next_bvar++, sign, p, q, d);
new_constraint(c);
return c->bvar();
return new_constraint(constraint::ule(m_level, m_next_bvar++, sign, p, q, d));
}
bool_var solver::new_sle(pdd const& p, pdd const& q, unsigned dep, csign_t sign) {
// To do signed comparison of bitvectors, flip the msb and do unsigned comparison:
//
// x <=s y <=> x + 2^(w-1) <=u y + 2^(w-1)
//
// Example for bit width 3:
// 111 -1
// 110 -2
// 101 -3
// 100 -4
// 011 3
// 010 2
// 001 1
// 000 0
//
// Argument: flipping the msb swaps the negative and non-negative blocks
auto shift = rational::power_of_two(p.power_of_2() - 1);
return new_ule(p + shift, q + shift, dep, sign);
p_dependency_ref d(mk_dep(dep), m_dm);
return new_constraint(constraint::sle(m_level, m_next_bvar++, sign, p, q, d));
}
bool_var solver::new_ult(pdd const& p, pdd const& q, unsigned dep) {
@ -257,6 +240,11 @@ namespace polysat {
push_qhead();
while (can_propagate())
propagate(m_search[m_qhead++].first);
linear_propagate();
}
void solver::linear_propagate() {
switch (m_linear_solver.check()) {
case l_false:
// TODO extract conflict