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slicing: change how values are tracked

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Do not eagerly merge equivalence classes with the same constant value.

Reason:
- when we split a value slice, the subslice might already exist in the
  egraph and already have subslices itself, which breaks assumptions in
  split/split_core.
- introduces unnecessary splits

Now:
- wrap constants into fresh function symbol before creating the enode
- check value compatibility in on_merge callback instead
- track pointer to value_node for each enode, and update it in on_merge
This commit is contained in:
Jakob Rath 2023-08-17 17:05:59 +02:00
parent 08928d041a
commit c95ff56d2d
3 changed files with 304 additions and 109 deletions
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114
src/test/slicing.cpp
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@ -29,7 +29,9 @@ namespace polysat {
class scoped_solver_slicing : public solver_scope_slicing, public solver {
public:
scoped_solver_slicing(): solver(lim, pars) {}
scoped_solver_slicing(): solver(lim, pars) {
set_log_enabled(false);
}
slicing& sl() { return m_slicing; }
};
@ -75,12 +77,14 @@ namespace polysat {
VERIFY(sl.merge(y_5_0, sl.var2slice(b), sat::literal(2)));
std::cout << sl << "\n";
/*
slicing::enode_vector x_base;
sl.get_root_base(sl.var2slice(x), x_base);
slicing::enode_vector y_base;
sl.get_root_base(sl.var2slice(y), y_base);
VERIFY(sl.merge(x_base, y_base, sat::literal(3)));
std::cout << sl << "\n";
*/
sl.display_tree(std::cout);
VERIFY(sl.invariant());
@ -212,6 +216,11 @@ namespace polysat {
// x[3:0] = z
// y = 0b1001
// z = 0b0111
//
// x: xxxxxx
// y: 1001
// z: 0111
// (no conflict)
static void test5() {
std::cout << __func__ << "\n";
scoped_solver_slicing s;
@ -232,6 +241,43 @@ namespace polysat {
VERIFY(sl.merge(sl.var2slice(z), seven, sat::literal(107)));
std::cout << "v" << z << " = 7\n" << sl << "\n";
VERIFY(!sl.is_conflict());
sl.display_tree(std::cout);
VERIFY(sl.invariant());
}
// x[5:2] = y
// x[3:0] = z
// y = 0b1001
// z = 0b1011
//
// x: xxxxxx
// y: 1001
// z: 1011
// (conflict)
static void test5b() {
std::cout << __func__ << "\n";
scoped_solver_slicing s;
slicing& sl = s.sl();
pvar x = s.add_var(6);
std::cout << sl << "\n";
pvar y = sl.mk_extract(x, 5, 2);
std::cout << "v" << y << " := v" << x << "[5:2]\n" << sl << "\n";
pvar z = sl.mk_extract(x, 3, 0);
std::cout << "v" << z << " := v" << x << "[3:0]\n" << sl << "\n";
slicing::enode* nine = sl.mk_value_slice(rational(9), 4);
VERIFY(sl.merge(sl.var2slice(y), nine, sat::literal(109)));
std::cout << "v" << y << " = 9\n" << sl << "\n";
slicing::enode* eleven = sl.mk_value_slice(rational(11), 4);
VERIFY(!sl.merge(sl.var2slice(z), eleven, sat::literal(107)));
std::cout << "v" << z << " = 11\n" << sl << "\n";
VERIFY(sl.is_conflict());
sl.display_tree(std::cout);
VERIFY(sl.invariant());
}
@ -264,7 +310,6 @@ namespace polysat {
// in various permutations
static void test7() {
std::cout << __func__ << "\n";
scoped_set_log_enabled _logging(false);
scoped_solver_slicing s;
slicing& sl = s.sl();
pdd x = s.var(s.add_var(8));
@ -374,6 +419,68 @@ namespace polysat {
VERIFY(sl.invariant());
}
// x == 7
// y == 7
static void test11() {
std::cout << __func__ << "\n";
scoped_solver_slicing s;
slicing& sl = s.sl();
pvar x = s.add_var(8);
sl.add_constraint(s.eq(s.var(x), 7));
pvar a = sl.mk_extract(x, 7, 6);
pvar b = sl.mk_extract(x, 3, 0);
sl.display_tree(std::cout);
pvar y = s.add_var(8);
pvar c = sl.mk_extract(y, 7, 6);
pvar d = sl.mk_extract(y, 1, 0);
sl.display_tree(std::cout);
sl.add_constraint(s.eq(s.var(y), 7));
sl.display_tree(std::cout);
}
// x == 0
// x != y
// y <= 1
// y[0:0] = z
// z == w
// w == 0
static void test12() {
std::cout << __func__ << "\n";
// TODO
scoped_solver_slicing s;
slicing& sl = s.sl();
}
// mk_extract y := x[63:32]
// a * x = 123
// b * y = 456
// a = 1, propagates x = 123 (by constraint)
// b = 1, propagates y = 456 (by constraint), propagates x = 0 (by slicing)
// Conflict in slicing.
static void test13() {
std::cout << __func__ << "\n";
scoped_solver_slicing s;
slicing& sl = s.sl();
pvar x = s.add_var(64);
pvar y = sl.mk_extract(x, 63, 32);
pvar a = s.add_var(64);
pvar b = s.add_var(32);
sl.add_constraint(s.eq(s.var(a)*s.var(x), 123)); // NOTE: this does nothing inside slicing atm.
sl.add_constraint(s.eq(s.var(b)*s.var(y), 456));
sl.add_value(a, 1);
sl.add_value(x, 123);
sl.add_value(b, 1);
sl.add_value(y, 456);
VERIFY(sl.is_conflict());
sl.display_tree(std::cout);
VERIFY(sl.invariant());
}
}; // test_slicing
} // namespace polysat
@ -386,10 +493,13 @@ void tst_slicing() {
test_slicing::test3();
test_slicing::test4();
test_slicing::test5();
test_slicing::test5b();
test_slicing::test6();
test_slicing::test7();
test_slicing::test8();
test_slicing::test9();
test_slicing::test10();
test_slicing::test11();
test_slicing::test13();
std::cout << "ok\n";
}