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Different slices of the same variable have the same hash

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This commit is contained in:
CEisenhofer 2026-06-28 14:36:35 +02:00
parent 79cdc91a75
commit cc42304f60
4 changed files with 56 additions and 17 deletions
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19
src/ast/euf/euf_sgraph.cpp
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@ -28,6 +28,8 @@ namespace euf {
m(m),
m_seq(m),
m_rewriter(m),
m_th_rewriter(m),
m_sk(m, m_th_rewriter),
m_egraph(eg),
m_str_sort(m_seq.str.mk_string_sort(), m),
m_pin(m) {
@ -305,7 +307,7 @@ namespace euf {
}
}
static const unsigned HASH_BASE = 31;
static constexpr unsigned HASH_BASE = 31;
// Compute a 2x2 polynomial hash matrix for associativity-respecting hashing.
// Unsigned overflow is intentional and well-defined (mod 2^32).
@ -333,7 +335,20 @@ namespace euf {
else {
// leaf/token: [[HASH_BASE, value], [0, 1]]
// +1 avoids zero hash values; wraps safely on unsigned overflow
unsigned v = n->get_expr() ? n->get_expr()->get_id() + 1 : n->id() + 1;
// for slices it is the same as its parent
expr* e = n->get_expr();
SASSERT(e);
unsigned v;
if (m_sk.is_slice(e)) {
do {
// get root variable
e = to_app(e)->get_arg(0);
} while (m_sk.is_slice(e));
v = e->get_id();
}
else
v = e->get_id() + 1;
n->m_hash_matrix[0][0] = HASH_BASE;
n->m_hash_matrix[0][1] = v;
n->m_hash_matrix[1][0] = 0;