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more rewrites based on example in #5457

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This commit is contained in:
Nikolaj Bjorner 2021-08-05 11:54:13 -07:00
parent e10850e66a
commit dcfd7b76c9
1 changed files with 32 additions and 0 deletions
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32
src/tactic/core/reduce_invertible_tactic.cpp
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@ -414,6 +414,38 @@ private:
return true;
}
}
//
// v <= u
// => u + 1 == 0 or delta
// v := delta ? u : u + 1
//
if (m_bv.is_bv_ule(p, e1, e2) && e1 == v && mc) {
ensure_mc(mc);
unsigned sz = m_bv.get_bv_size(e2);
expr_ref delta(m.mk_fresh_const("ule", m.mk_bool_sort()), m);
expr_ref succ_e2(m_bv.mk_bv_add(e2, m_bv.mk_numeral(1, sz)), m);
new_v = m.mk_or(delta, m.mk_eq(succ_e2, m_bv.mk_numeral(0, sz)));
(*mc)->hide(delta);
(*mc)->add(v, m.mk_ite(delta, e2, succ_e2));
return true;
}
//
// u <= v
// => u == 0 or delta
// v := delta ? u : u - 1
//
if (m_bv.is_bv_ule(p, e1, e2) && e2 == v && mc) {
ensure_mc(mc);
unsigned sz = m_bv.get_bv_size(e1);
expr_ref delta(m.mk_fresh_const("ule", m.mk_bool_sort()), m);
expr_ref pred_e1(m_bv.mk_bv_sub(e1, m_bv.mk_numeral(1, sz)), m);
new_v = m.mk_or(delta, m.mk_eq(e1, m_bv.mk_numeral(0, sz)));
(*mc)->hide(delta);
(*mc)->add(v, m.mk_ite(delta, e1, pred_e1));
return true;
}
return false;
}