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slicing: track disequalities

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This commit is contained in:
Jakob Rath 2023-07-19 12:04:45 +02:00
parent 970e68c70e
commit af73f26941
4 changed files with 157 additions and 17 deletions
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9
src/math/polysat/slicing.h
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@ -63,10 +63,11 @@ namespace polysat {
static constexpr unsigned null_cut = std::numeric_limits<unsigned>::max();
// Kinds of slices:
// - proper (from variables)
// We use the following kinds of enodes:
// - proper slices (of variables)
// - values
// - virtual concat(...) expressions
// - equalities between enodes (to track disequalities; currently not represented in slice_info)
struct slice_info {
unsigned width = 0; // number of bits in the slice
// Cut point: if not null_cut, the slice s has been subdivided into s[|s|-1:cut+1] and s[cut:0].
@ -95,6 +96,7 @@ namespace polysat {
slice_info_vector m_info; // indexed by enode::get_id()
enode_vector m_var2slice; // pvar -> slice
tracked_uint_set m_needs_congruence; // set of pvars that need updated concat(...) expressions
enode* m_disequality_conflict = nullptr;
// Add an equation v = concat(s1, ..., sn)
// for each variable v with base slices s1, ..., sn
@ -113,6 +115,7 @@ namespace polysat {
enode* alloc_enode(expr* e, unsigned num_args, enode* const* args, unsigned width, pvar var);
enode* find_or_alloc_enode(expr* e, unsigned num_args, enode* const* args, unsigned width, pvar var);
enode* alloc_slice(unsigned width, pvar var = null_var);
enode* find_or_alloc_disequality(enode* x, enode* y, sat::literal lit);
enode* var2slice(pvar v) const { return m_var2slice[v]; }
pvar slice2var(enode* s) const { return info(s).var; }
@ -245,7 +248,7 @@ namespace polysat {
// update congruences, egraph
void propagate();
bool is_conflict() const { return m_egraph.inconsistent(); }
bool is_conflict() const { return m_disequality_conflict || m_egraph.inconsistent(); }
/** Extract reason for conflict */
void explain(sat::literal_vector& out_lits, unsigned_vector& out_vars);