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Update sgraph and seq_plugin: egraph ref, hash matrix, subst cache, sgraph pointer

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Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>
This commit is contained in:
copilot-swe-agent[bot] 2026-03-02 21:14:34 +00:00
parent 1885753690
commit cfea2db8bf
8 changed files with 174 additions and 42 deletions
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88
src/ast/euf/euf_sgraph.cpp
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@ -23,15 +23,35 @@ Author:
namespace euf {
sgraph::sgraph(ast_manager& m):
// substitution cache stored on snode for ZIPT-style optimization
struct snode_subst_cache {
struct entry {
unsigned var_id;
unsigned repl_id;
snode* result;
};
svector<entry> m_entries;
snode* find(unsigned var_id, unsigned repl_id) const {
for (auto const& e : m_entries)
if (e.var_id == var_id && e.repl_id == repl_id)
return e.result;
return nullptr;
}
void insert(unsigned var_id, unsigned repl_id, snode* result) {
m_entries.push_back({var_id, repl_id, result});
}
};
sgraph::sgraph(ast_manager& m, egraph& eg, bool add_plugin):
m(m),
m_seq(m),
m_rewriter(m),
m_egraph(m),
m_exprs(m),
m_str_sort(m_seq.str.mk_string_sort(), m) {
m_egraph(eg),
m_str_sort(m_seq.str.mk_string_sort(), m),
m_add_plugin(add_plugin) {
// create seq_plugin and register it with the egraph
m_egraph.add_plugin(alloc(seq_plugin, m_egraph));
if (add_plugin)
m_egraph.add_plugin(alloc(seq_plugin, m_egraph, this));
// register on_make callback so sgraph creates snodes for new enodes
std::function<void(enode*)> on_make = [this](enode* n) {
expr* e = n->get_expr();
@ -42,6 +62,8 @@ namespace euf {
}
sgraph::~sgraph() {
for (auto* c : m_subst_caches)
dealloc(c);
}
snode_kind sgraph::classify(expr* e) const {
@ -265,16 +287,49 @@ namespace euf {
}
}
static const unsigned HASH_BASE = 31;
void sgraph::compute_hash_matrix(snode* n) {
if (n->is_empty()) {
// identity matrix: concat with empty is identity
n->m_hash_matrix[0][0] = 1;
n->m_hash_matrix[0][1] = 0;
n->m_hash_matrix[1][0] = 0;
n->m_hash_matrix[1][1] = 1;
}
else if (n->is_concat()) {
snode* l = n->arg(0);
snode* r = n->arg(1);
if (l->has_cached_hash() && r->has_cached_hash()) {
// 2x2 matrix multiplication: M(L) * M(R)
n->m_hash_matrix[0][0] = l->m_hash_matrix[0][0] * r->m_hash_matrix[0][0] + l->m_hash_matrix[0][1] * r->m_hash_matrix[1][0];
n->m_hash_matrix[0][1] = l->m_hash_matrix[0][0] * r->m_hash_matrix[0][1] + l->m_hash_matrix[0][1] * r->m_hash_matrix[1][1];
n->m_hash_matrix[1][0] = l->m_hash_matrix[1][0] * r->m_hash_matrix[0][0] + l->m_hash_matrix[1][1] * r->m_hash_matrix[1][0];
n->m_hash_matrix[1][1] = l->m_hash_matrix[1][0] * r->m_hash_matrix[0][1] + l->m_hash_matrix[1][1] * r->m_hash_matrix[1][1];
}
}
else {
// leaf/token: [[HASH_BASE, value], [0, 1]]
unsigned v = n->get_expr() ? n->get_expr()->get_id() + 1 : n->id() + 1;
n->m_hash_matrix[0][0] = HASH_BASE;
n->m_hash_matrix[0][1] = v;
n->m_hash_matrix[1][0] = 0;
n->m_hash_matrix[1][1] = 1;
}
}
snode* sgraph::mk_snode(expr* e, snode_kind k, unsigned num_args, snode* const* args) {
unsigned id = m_nodes.size();
snode* n = snode::mk(m_region, e, k, id, num_args, args);
compute_metadata(n);
compute_hash_matrix(n);
m_nodes.push_back(n);
m_exprs.push_back(e);
if (e) {
unsigned eid = e->get_id();
m_expr2snode.reserve(eid + 1, nullptr);
m_expr2snode[eid] = n;
// pin expression via egraph (the egraph has an expr trail)
mk_enode(e);
}
++m_stats.m_num_nodes;
return n;
@ -350,7 +405,6 @@ namespace euf {
}
}
m_nodes.shrink(old_sz);
m_exprs.shrink(old_sz);
m_scopes.shrink(new_lvl);
m_num_scopes = new_lvl;
m_egraph.pop(num_scopes);
@ -418,9 +472,23 @@ namespace euf {
return replacement;
if (n->is_empty() || n->is_char())
return n;
if (n->is_concat())
return mk_concat(subst(n->arg(0), var, replacement),
subst(n->arg(1), var, replacement));
if (n->is_concat()) {
// check substitution cache (ZIPT-style optimization)
if (n->m_subst_cache) {
snode* cached = n->m_subst_cache->find(var->id(), replacement->id());
if (cached)
return cached;
}
snode* result = mk_concat(subst(n->arg(0), var, replacement),
subst(n->arg(1), var, replacement));
// cache the result
if (!n->m_subst_cache) {
n->m_subst_cache = alloc(snode_subst_cache);
m_subst_caches.push_back(n->m_subst_cache);
}
n->m_subst_cache->insert(var->id(), replacement->id(), result);
return result;
}
// for non-concat compound nodes (power, star, etc.), no substitution into children
return n;
}