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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
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@NikolajBjorner
NikolajBjorner committed Mar 5, 2024
1 parent 531bda3 commit d6f522e
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Showing 5 changed files with 83 additions and 27 deletions.
7 changes: 4 additions & 3 deletions src/ast/sls/bv_sls.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,7 @@ namespace bv {
void sls::reinit_eval() {
std::function<bool(expr*, unsigned)> eval = [&](expr* e, unsigned i) {
auto should_keep = [&]() {
return m_rand() % 100 >= 98;
return m_rand() % 100 <= 92;
};
if (m.is_bool(e)) {
if (m_eval.is_fixed0(e) || should_keep())
Expand Down Expand Up @@ -127,11 +127,12 @@ namespace bv {
if (!e)
return l_true;

++m_stats.m_moves;

trace_repair(down, e);

if (down)
++m_stats.m_moves;

if (down)
try_repair_down(e);
else
try_repair_up(e);
Expand Down
64 changes: 44 additions & 20 deletions src/ast/sls/bv_sls_eval.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ namespace bv {
continue;
app* a = to_app(e);
if (bv.is_bv(e))
add_bit_vector(e);
add_bit_vector(a);
if (a->get_family_id() == basic_family_id)
init_eval_basic(a);
else if (a->get_family_id() == bv.get_family_id())
Expand All @@ -40,7 +40,7 @@ namespace bv {
auto& v = wval(e);
for (unsigned i = 0; i < v.bw; ++i)
m_tmp.set(i, eval(e, i));
v.set(m_tmp);
v.set_repair(random_bool(), m_tmp);
}
else if (m.is_bool(e))
m_eval.setx(e->get_id(), eval(e, 0), false);
Expand Down Expand Up @@ -78,16 +78,21 @@ namespace bv {
return m_todo;
}

bool sls_eval::add_bit_vector(expr* e) {
auto bw = bv.get_bv_size(e);
bool sls_eval::add_bit_vector(app* e) {
m_values.reserve(e->get_id() + 1);
if (m_values.get(e->get_id()))
return false;
m_values.set(e->get_id(), alloc_valuation(bw));
auto v = alloc_valuation(e);
m_values.set(e->get_id(), v);
if (bv.is_sign_ext(e)) {
unsigned p = e->get_parameter(0).get_int();
v->set_signed(p);
}
return true;
}

sls_valuation* sls_eval::alloc_valuation(unsigned bit_width) {
sls_valuation* sls_eval::alloc_valuation(app* e) {
auto bit_width = bv.get_bv_size(e);
auto* r = alloc(sls_valuation, bit_width);
while (m_tmp.size() < 2 * r->nw) {
m_tmp.push_back(0);
Expand Down Expand Up @@ -905,8 +910,14 @@ namespace bv {
}

bool sls_eval::try_repair_eq(bool is_true, bvval& a, bvval const& b) {
if (is_true)
return a.try_set(b.bits());
if (is_true) {
if (m_rand() % 20 != 0)
if (a.try_set(b.bits()))
return true;

a.get_variant(m_tmp, m_rand);
return a.set_repair(random_bool(), m_tmp);
}
else {
bool try_above = m_rand() % 2 == 0;
if (try_above) {
Expand Down Expand Up @@ -1004,22 +1015,26 @@ namespace bv {
// If this fails, set a to a random value
//
bool sls_eval::try_repair_add(bvect const& e, bvval& a, bvval const& b) {
a.set_sub(m_tmp, e, b.bits());
if (a.try_set(m_tmp))
return true;
if (m_rand() % 20 != 0) {
a.set_sub(m_tmp, e, b.bits());
if (a.try_set(m_tmp))
return true;
}
a.get_variant(m_tmp, m_rand);
return a.set_repair(random_bool(), m_tmp);
}

bool sls_eval::try_repair_sub(bvect const& e, bvval& a, bvval & b, unsigned i) {
if (i == 0)
// e = a - b -> a := e + b
a.set_add(m_tmp, e, b.bits());
else
// b := a - e
b.set_sub(m_tmp, a.bits(), e);
if (a.try_set(m_tmp))
return true;
if (m_rand() % 20 != 0) {
if (i == 0)
// e = a - b -> a := e + b
a.set_add(m_tmp, e, b.bits());
else
// b := a - e
b.set_sub(m_tmp, a.bits(), e);
if (a.try_set(m_tmp))
return true;
}
// fall back to a random value
a.get_variant(m_tmp, m_rand);
return a.set_repair(random_bool(), m_tmp);
Expand All @@ -1045,6 +1060,11 @@ namespace bv {
return a.set_repair(random_bool(), m_tmp);
}

if (m_rand() % 20 == 0) {
a.get_variant(m_tmp, m_rand);
return a.set_repair(random_bool(), m_tmp);
}

#if 0
verbose_stream() << "solve for " << e << "\n";

Expand Down Expand Up @@ -1125,7 +1145,11 @@ namespace bv {
if (parity_e > 0 && parity_b > 0)
b.shift_right(m_tmp2, std::min(parity_b, parity_e));
a.set_mul(m_tmp, tb, m_tmp2);
return a.set_repair(random_bool(), m_tmp);
if (a.set_repair(random_bool(), m_tmp))
return true;

a.get_variant(m_tmp, m_rand);
return a.set_repair(random_bool(), m_tmp);
}

bool sls_eval::try_repair_bnot(bvect const& e, bvval& a) {
Expand Down
6 changes: 3 additions & 3 deletions src/ast/sls/bv_sls_eval.h
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Original file line number Diff line number Diff line change
Expand Up @@ -59,8 +59,8 @@ namespace bv {
* Register e as a bit-vector.
* Return true if not already registered, false if already registered.
*/
bool add_bit_vector(expr* e);
sls_valuation* alloc_valuation(unsigned bit_width);
bool add_bit_vector(app* e);
sls_valuation* alloc_valuation(app* e);

bool bval1_basic(app* e) const;
bool bval1_bv(app* e) const;
Expand Down Expand Up @@ -143,7 +143,7 @@ namespace bv {

sls_valuation& wval(expr* e) const;

bool is_fixed0(expr* e) const { return m_fixed[e->get_id()]; }
bool is_fixed0(expr* e) const { return m_fixed.get(e->get_id(), false); }

/**
* Retrieve evaluation based on immediate children.
Expand Down
29 changes: 28 additions & 1 deletion src/ast/sls/sls_valuation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -307,18 +307,21 @@ namespace bv {
void sls_valuation::round_down(bvect& dst, std::function<bool(bvect const&)> const& is_feasible) {
for (unsigned i = bw; !is_feasible(dst) && i-- > 0; )
if (!fixed.get(i) && dst.get(i))
dst.set(i, false);
dst.set(i, false);
repair_sign_bits(dst);
}

void sls_valuation::round_up(bvect& dst, std::function<bool(bvect const&)> const& is_feasible) {
for (unsigned i = 0; !is_feasible(dst) && i < bw; ++i)
if (!fixed.get(i) && !dst.get(i))
dst.set(i, true);
repair_sign_bits(dst);
}

void sls_valuation::set_random_above(bvect& dst, random_gen& r) {
for (unsigned i = 0; i < nw; ++i)
dst[i] = dst[i] | (random_bits(r) & ~fixed[i]);
repair_sign_bits(dst);
}

void sls_valuation::set_random_below(bvect& dst, random_gen& r) {
Expand All @@ -335,12 +338,14 @@ namespace bv {
for (unsigned i = 0; i < idx; ++i)
if (!fixed.get(i))
dst.set(i, r() % 2 == 0);
repair_sign_bits(dst);
}

bool sls_valuation::set_repair(bool try_down, bvect& dst) {
for (unsigned i = 0; i < nw; ++i)
dst[i] = (~fixed[i] & dst[i]) | (fixed[i] & m_bits[i]);

repair_sign_bits(dst);
if (in_range(dst)) {
set(eval, dst);
return true;
Expand All @@ -363,6 +368,7 @@ namespace bv {
if (!fixed.get(i) && dst.get(i))
dst.set(i, false);
}
repair_sign_bits(dst);
if (in_range(dst)) {
set(eval, dst);
repaired = true;
Expand All @@ -378,6 +384,7 @@ namespace bv {
for (unsigned i = 0; i < nw; ++i)
out[i] = fixed[i] & m_bits[i];
}
repair_sign_bits(out);
SASSERT(!has_overflow(out));
}

Expand All @@ -390,6 +397,7 @@ namespace bv {
for (unsigned i = 0; i < nw; ++i)
out[i] = ~fixed[i] | m_bits[i];
}
repair_sign_bits(out);
SASSERT(!has_overflow(out));
}

Expand Down Expand Up @@ -421,9 +429,28 @@ namespace bv {
void sls_valuation::get_variant(bvect& dst, random_gen& r) const {
for (unsigned i = 0; i < nw; ++i)
dst[i] = (random_bits(r) & ~fixed[i]) | (fixed[i] & m_bits[i]);
repair_sign_bits(dst);
clear_overflow_bits(dst);
}

void sls_valuation::repair_sign_bits(bvect& dst) const {
if (m_signed_prefix == 0)
return;
bool sign = dst.get(bw - 1);
for (unsigned i = bw; i-- >= bw - m_signed_prefix; ) {
if (dst.get(i) != sign) {
if (fixed.get(i)) {
for (unsigned i = bw; i-- >= bw - m_signed_prefix; )
if (!fixed.get(i))
dst.set(i, !sign);
return;
}
else
dst.set(i, sign);
}
}
}

//
// new_bits != bits => ~fixed
// 0 = (new_bits ^ bits) & fixed
Expand Down
4 changes: 4 additions & 0 deletions src/ast/sls/sls_valuation.h
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Original file line number Diff line number Diff line change
Expand Up @@ -96,11 +96,14 @@ namespace bv {
protected:
bvect m_bits;
bvect m_lo, m_hi; // range assignment to bit-vector, as wrap-around interval
unsigned m_signed_prefix = 0;

unsigned mask;
bool round_up(bvect& dst) const;
bool round_down(bvect& dst) const;

void repair_sign_bits(bvect& dst) const;


public:
unsigned bw; // bit-width
Expand All @@ -111,6 +114,7 @@ namespace bv {
sls_valuation(unsigned bw);

void set_bw(unsigned bw);
void set_signed(unsigned prefix) { m_signed_prefix = prefix; }

unsigned num_bytes() const { return (bw + 7) / 8; }

Expand Down

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