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working on #5614

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there are some different sources for the performance regression illustrated by the example. The mitigations will be enabled separately:
- m_bv_to_propagate is too expensive
- lp_bound_propagator misses equalities in two different ways:
   - it resets row checks after backtracking even though they could still propagate
   - it misses equalities for fixed rows when the fixed constant value does not correspond to a fixed variable.

FYI @levnach
This commit is contained in:
Nikolaj Bjorner 2021-11-02 14:55:28 -07:00
parent a94e2e62af
commit 87d4ce2659
13 changed files with 422 additions and 385 deletions
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23
src/math/lp/lar_solver.h
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@ -76,13 +76,13 @@ class lar_solver : public column_namer {
//////////////////// fields //////////////////////////
lp_settings m_settings;
lp_status m_status;
lp_status m_status = lp_status::UNKNOWN;
stacked_value<simplex_strategy_enum> m_simplex_strategy;
// such can be found at the initialization step: u < l
stacked_value<int> m_crossed_bounds_column;
lar_core_solver m_mpq_lar_core_solver;
int_solver * m_int_solver;
bool m_need_register_terms;
int_solver * m_int_solver = nullptr;
bool m_need_register_terms = false;
var_register m_var_register;
var_register m_term_register;
stacked_vector<ul_pair> m_columns_to_ul_pairs;
@ -90,6 +90,8 @@ class lar_solver : public column_namer {
// the set of column indices j such that bounds have changed for j
u_set m_columns_with_changed_bounds;
u_set m_rows_with_changed_bounds;
unsigned_vector m_row_bounds_to_replay;
u_set m_basic_columns_with_changed_cost;
// these are basic columns with the value changed, so the the corresponding row in the tableau
// does not sum to zero anymore
@ -164,7 +166,6 @@ class lar_solver : public column_namer {
void adjust_initial_state_for_lu();
void adjust_initial_state_for_tableau_rows();
void fill_last_row_of_A_d(static_matrix<double, double> & A, const lar_term* ls);
void clear();
bool use_lu() const;
bool sizes_are_correct() const;
bool implied_bound_is_correctly_explained(implied_bound const & be, const vector<std::pair<mpq, unsigned>> & explanation) const;
@ -219,6 +220,7 @@ class lar_solver : public column_namer {
void change_basic_columns_dependend_on_a_given_nb_column(unsigned j, const numeric_pair<mpq> & delta);
void update_x_and_inf_costs_for_column_with_changed_bounds(unsigned j);
unsigned num_changed_bounds() const { return m_rows_with_changed_bounds.size(); }
void insert_row_with_changed_bounds(unsigned rid);
void detect_rows_with_changed_bounds_for_column(unsigned j);
void detect_rows_with_changed_bounds();
void set_value_for_nbasic_column(unsigned j, const impq & new_val);
@ -368,20 +370,19 @@ public:
// these two loops should be run sequentially
// since the first loop might change column bounds
// and add fixed columns this way
if (settings().cheap_eqs()) {
if (settings().propagate_eqs()) {
bp.clear_for_eq();
for (unsigned i : m_rows_with_changed_bounds) {
calculate_cheap_eqs_for_row(i, bp);
unsigned offset_eqs = stats().m_offset_eqs;
bp.cheap_eq_tree(i);
if (settings().get_cancel_flag())
return;
if (stats().m_offset_eqs > offset_eqs)
m_row_bounds_to_replay.push_back(i);
}
}
m_rows_with_changed_bounds.clear();
}
template <typename T>
void calculate_cheap_eqs_for_row(unsigned i, lp_bound_propagator<T> & bp) {
bp.cheap_eq_tree(i);
}
bool is_fixed(column_index const& j) const { return column_is_fixed(j); }
inline column_index to_column_index(unsigned v) const { return column_index(external_to_column_index(v)); }
@ -515,6 +516,8 @@ public:
unsigned column_to_reported_index(unsigned j) const;
lp_settings & settings();
lp_settings const & settings() const;
statistics& stats();
void updt_params(params_ref const& p);
column_type get_column_type(unsigned j) const { return m_mpq_lar_core_solver.m_column_types()[j]; }
const impq & get_lower_bound(unsigned j) const { return m_mpq_lar_core_solver.m_r_lower_bounds()[j]; }