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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2020-09-03 09:34:09 -07:00
parent 7fbaf71d4a
commit f370d8d9b4
2 changed files with 68 additions and 7 deletions
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69
src/sat/smt/bv_internalize.cpp
View file

@ -267,6 +267,10 @@ namespace bv {
}
}
void solver::add_unit(sat::literal lit) {
s().add_clause(1, &lit, status());
}
void solver::init_bits(euf::enode * n, expr_ref_vector const & bits) {
SASSERT(get_bv_size(n) == bits.size());
SASSERT(euf::null_theory_var != n->get_th_var(get_id()));
@ -316,11 +320,12 @@ namespace bv {
assert_bv2int_axiom(n);
}
/**
* create the axiom:
* n = bv2int(k) = ite(bit2bool(k[sz-1],2^{sz-1},0) + ... + ite(bit2bool(k[0],1,0))
*/
void solver::assert_bv2int_axiom(app * n) {
//
// create the axiom:
// n = bv2int(k) = ite(bit2bool(k[sz-1],2^{sz-1},0) + ... + ite(bit2bool(k[0],1,0))
//
expr* k = nullptr;
sort * int_sort = m.get_sort(n);
SASSERT(bv.is_bv2int(n, k));
@ -340,7 +345,60 @@ namespace bv {
expr_ref sum(m_autil.mk_add(sz, args.c_ptr()), m);
expr_ref eq(m.mk_eq(n, sum), m);
sat::literal lit = ctx.internalize(eq, false, false, m_is_redundant);
s().add_clause(1, &lit, sat::status::th(m_is_redundant, get_id()));
add_unit(lit);
}
void solver::internalize_int2bv(app* n) {
SASSERT(bv.is_int2bv(n));
euf::enode* e = mk_enode(n, m_args);
theory_var v = e->get_th_var(get_id());
mk_bits(v);
assert_int2bv_axiom(n);
}
/**
* create the axiom:
* bv2int(n) = e mod 2^bit_width
* where n = int2bv(e)
*
* Create the axioms:
* bit2bool(i,n) == ((e div 2^i) mod 2 != 0)
* for i = 0,.., sz-1
*/
void solver::assert_int2bv_axiom(app* n) {
SASSERT(bv.is_int2bv(n));
expr* e = n->get_arg(0);
euf::enode* n_enode = mk_enode(n, m_args);
parameter param(m_autil.mk_int());
expr* n_expr = n;
expr_ref lhs(m), rhs(m);
lhs = m.mk_app(get_id(), OP_BV2INT, 1, &param, 1, &n_expr);
unsigned sz = bv.get_bv_size(n);
numeral mod = power(numeral(2), sz);
rhs = m_autil.mk_mod(e, m_autil.mk_numeral(mod, true));
expr_ref eq(m.mk_eq(lhs, rhs), m);
literal l = ctx.internalize(eq, false, false, m_is_redundant);
add_unit(l);
TRACE("bv", tout << eq << "\n";);
expr_ref_vector n_bits(m);
get_bits(n_enode, n_bits);
for (unsigned i = 0; i < sz; ++i) {
numeral div = power(numeral(2), i);
mod = numeral(2);
rhs = m_autil.mk_idiv(e, m_autil.mk_numeral(div, true));
rhs = m_autil.mk_mod(rhs, m_autil.mk_numeral(mod, true));
rhs = m.mk_eq(rhs, m_autil.mk_numeral(rational(1), true));
lhs = n_bits.get(i);
expr_ref eq(m.mk_eq(lhs, rhs), m);
TRACE("bv", tout << eq << "\n";);
l = ctx.internalize(eq, false, false, m_is_redundant);
add_unit(l);
}
}
@ -373,7 +431,6 @@ namespace bv {
void solver::internalize_comp(app* n) {}
void solver::internalize_rotate_left(app* n) {}
void solver::internalize_rotate_right(app* n) {}
void solver::internalize_int2bv(app* n) {}
void solver::internalize_umul_no_overflow(app* n) {}
void solver::internalize_smul_no_overflow(app* n) {}
void solver::internalize_smul_no_underflow(app* n) {}

6
src/sat/smt/bv_solver.h
View file

@ -121,7 +121,7 @@ namespace bv {
sat::literal true_literal;
bool visit(expr* e) override;
bool visited(expr* e) override;
bool post_visit(expr* e, bool sign, bool root) override;
bool post_visit(expr* e, bool sign, bool root) override { return true; }
unsigned get_bv_size(euf::enode* n);
unsigned get_bv_size(theory_var v);
theory_var get_var(euf::enode* n);
@ -133,6 +133,9 @@ namespace bv {
void get_arg_bits(app* n, unsigned idx, expr_ref_vector& r);
euf::enode* mk_enode(expr* n, ptr_vector<euf::enode> const& args);
void fixed_var_eh(theory_var v);
sat::status status() const { return sat::status::th(m_is_redundant, get_id()); }
void add_unit(sat::literal lit);
void register_true_false_bit(theory_var v, unsigned i);
void add_bit(theory_var v, sat::literal lit);
void init_bits(euf::enode * n, expr_ref_vector const & bits);
@ -176,6 +179,7 @@ namespace bv {
void internalize_smul_no_underflow(app *n);
void assert_bv2int_axiom(app * n);
void assert_int2bv_axiom(app* n);
// solving
void find_wpos(theory_var v);