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debug iterative deepening some more and add first attempt at PQ (untested)

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Ilana Shapiro 2025-08-29 15:41:05 -07:00
parent a42d21fe80
commit 651b86000f
3 changed files with 108 additions and 16 deletions
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1
src/params/smt_parallel_params.pyg
View file

@ -16,4 +16,5 @@ def_module_params('smt_parallel',
('depth_splitting_only', BOOL, False, 'only apply frugal cube strategy, and only on deepest (biggest) cubes from the batch manager'),
('backbone_detection', BOOL, False, 'apply backbone literal heuristic'),
('iterative_deepening', BOOL, False, 'deepen cubes based on iterative hardness cutoff heuristic'),
('beam_search', BOOL, False, 'use beam search with PQ to rank cubes given to threads'),
))

90
src/smt/smt_parallel.cpp
View file

@ -110,7 +110,7 @@ namespace smt {
const double avg_hardness = b.update_avg_cube_hardness(cube_hardness);
const double factor = 1; // can tune for multiple of avg hardness later
bool should_split = cube_hardness >= avg_hardness * factor;
LOG_WORKER(1, " cube hardness: " << cube_hardness << " avg: " << avg_hardness << " should-split: " << should_split << "\n");
LOG_WORKER(1, " cube hardness: " << cube_hardness << " avg: " << avg_hardness << " avg*factor: " << avg_hardness * factor << " should-split: " << should_split << "\n");
// we still need to call return_cubes, even if we don't split, since we need to re-enqueue the current unsolved cube to the batch manager!
// should_split tells return_cubes whether to further split the unsolved cube.
b.return_cubes(m_l2g, returned_cubes, split_atoms, should_split);
@ -329,9 +329,9 @@ namespace smt {
void parallel::batch_manager::get_cubes(ast_translation& g2l, vector<expr_ref_vector>& cubes) {
std::scoped_lock lock(mux);
if (m_config.m_beam_search) {
} else if (m_cubes.size() == 1 && m_cubes[0].empty()) {
if (m_cubes.size() == 1 && m_cubes[0].empty()
|| m_config.m_beam_search && m_cubes_pq.empty()
|| m_config.m_depth_splitting_only && m_cubes_depth_sets.empty()) {
// special initialization: the first cube is emtpy, have the worker work on an empty cube.
cubes.push_back(expr_ref_vector(g2l.to()));
return;
@ -353,6 +353,19 @@ namespace smt {
deepest_cubes.erase(deepest_cubes.begin() + idx); // remove the cube from the set
if (deepest_cubes.empty())
m_cubes_depth_sets.erase(m_cubes_depth_sets.size() - 1);
} else if (m_config.m_beam_search) {
// get the highest ranked cube
SASSERT(!m_cubes_pq.empty());
ScoredCube const& scored_cube = m_cubes_pq.top();
auto& cube = scored_cube.cube;
expr_ref_vector l_cube(g2l.to());
for (auto& e : cube) {
l_cube.push_back(g2l(e));
}
cubes.push_back(l_cube);
m_cubes_pq.pop();
} else {
auto& cube = m_cubes.back();
expr_ref_vector l_cube(g2l.to());
@ -417,7 +430,7 @@ namespace smt {
return l_undef; // the main context was cancelled, so we return undef.
switch (m_state) {
case state::is_running: // batch manager is still running, but all threads have processed their cubes, which means all cubes were unsat
if (!m_cubes.empty() || (m_config.m_depth_splitting_only && !m_cubes_depth_sets.empty()))
if (!m_cubes.empty() || (m_config.m_depth_splitting_only && !m_cubes_depth_sets.empty()) || (m_config.m_beam_search && !m_cubes_pq.empty()))
throw default_exception("inconsistent end state");
if (!p.m_assumptions_used.empty()) {
// collect unsat core from assumptions used, if any --> case when all cubes were unsat, but depend on nonempty asms, so we need to add these asms to final unsat core
@ -516,11 +529,13 @@ namespace smt {
// apply the frugal strategy to ALL incoming worker cubes, but save in the deepest cube data structure
auto add_split_atom_deepest_cubes = [&](expr* atom) {
for (auto& c : C_worker) {
if (c.size() >= m_config.m_max_cube_depth || !should_split) {
IF_VERBOSE(1, verbose_stream() << " Skipping split of cube at max depth " << m_config.m_max_cube_depth << "\n";);
continue;
}
expr_ref_vector g_cube(l2g.to());
for (auto& atom : c)
g_cube.push_back(l2g(atom));
if (g_cube.size() >= m_config.m_max_cube_depth) // we already added this before!! we just need to add the splits now
continue;
// add depth set d+1 if it doesn't exist yet
unsigned d = g_cube.size();
@ -540,6 +555,36 @@ namespace smt {
}
};
// apply the frugal strategy to ALL incoming worker cubes, but save in the PQ data structure for beam search
auto add_split_atom_pq = [&](expr* atom) {
for (auto& c : C_worker) {
if (c.size() >= m_config.m_max_cube_depth || !should_split) {
IF_VERBOSE(1, verbose_stream() << " Skipping split of cube at max depth " << m_config.m_max_cube_depth << "\n";);
continue;
}
expr_ref_vector g_cube(l2g.to());
for (auto& atom : c)
g_cube.push_back(l2g(atom));
// i need to split on the positive and negative atom, and add both to the PQ. the score is the depth of the cube (same for both)
unsigned d = g_cube.size();
// Positive atom branch
expr_ref_vector cube_pos = g_cube;
cube_pos.push_back(atom);
m_cubes_pq.push(ScoredCube(d, cube_pos));
// Negative atom branch
expr_ref_vector cube_neg = g_cube;
cube_neg.push_back(m.mk_not(atom));
m_cubes_pq.push(ScoredCube(d, cube_neg));
m_stats.m_num_cubes += 2;
m_stats.m_max_cube_depth = std::max(m_stats.m_max_cube_depth, d + 1);
}
};
std::scoped_lock lock(mux);
unsigned max_greedy_cubes = 1000;
bool greedy_mode = (m_cubes.size() <= max_greedy_cubes) && !m_config.m_frugal_cube_only && !m_config.m_iterative_deepening; // for iterative deepening, our hardness metric is cube-specific, so it only makes sense for frugal approach for now
@ -557,6 +602,8 @@ namespace smt {
if (m_config.m_depth_splitting_only) {
add_split_atom_deepest_cubes(g_atom); // split all *existing* cubes in the depth sets data structure
} else if (m_config.m_beam_search) {
add_split_atom_pq(g_atom); // split all *existing* cubes in the priority queue data structure
} else {
add_split_atom(g_atom, 0); // split all *existing* cubes
}
@ -576,17 +623,26 @@ namespace smt {
for (auto& atom : c)
g_cube.push_back(l2g(atom));
if (m_config.m_depth_splitting_only || m_config.m_iterative_deepening) {
// the cube does NOT get overwritten by its split later.
// however, we do want to re-enqueue the cube if we don't split (in the iterative deepening case)
// currently, there limitation is that should_split is only correct when C_worker has size 1
// should-split is only false sometimes in the iterative deepening experiment (it's always true otherwise)
if ((c.size() >= m_config.m_max_cube_depth || !should_split)
&& (m_config.m_depth_splitting_only || m_config.m_iterative_deepening || m_config.m_beam_search)) {
if (m_config.m_beam_search) {
m_cubes_pq.push(ScoredCube(g_cube.size(), g_cube)); // re-enqueue the cube as is
} else {
// need to add the depth set if it doesn't exist yet
if (m_cubes_depth_sets.find(g_cube.size()) == m_cubes_depth_sets.end()) {
m_cubes_depth_sets[g_cube.size()] = vector<expr_ref_vector>();
}
m_cubes_depth_sets[g_cube.size()].push_back(g_cube);
m_stats.m_num_cubes += 1;
m_stats.m_max_cube_depth = std::max(m_stats.m_max_cube_depth, g_cube.size());
} else {
m_cubes.push_back(g_cube);
return; // don't split this cube further
}
} else {
m_cubes.push_back(g_cube); // the cube gets overwritten by its split later
}
// in the non-iterative-deepening PQ approach, we add the subcubes directly, otherwise we're re-enquing a cube that's already been worked on when we dont want to
if (greedy_mode) {
// Split new cube on all existing m_split_atoms not in it
@ -594,6 +650,8 @@ namespace smt {
if (!atom_in_cube(g_cube, g_atom)) {
if (m_config.m_depth_splitting_only) {
add_split_atom_deepest_cubes(g_atom); // split all *existing* cubes in the depth sets data structure
} else if (m_config.m_beam_search) {
add_split_atom_pq(g_atom);
} else {
add_split_atom(g_atom, 0); // split all *existing* cubes
}
@ -615,6 +673,8 @@ namespace smt {
if (should_split && (m_config.m_depth_splitting_only || m_config.m_iterative_deepening)) {
IF_VERBOSE(1, verbose_stream() << " splitting worker cubes on new atom " << mk_bounded_pp(g_atom, m, 3) << "\n");
add_split_atom_deepest_cubes(g_atom);
} else if (m_config.m_beam_search) {
add_split_atom_pq(g_atom);
} else {
add_split_atom(g_atom, initial_m_cubes_size);
}
@ -787,9 +847,12 @@ namespace smt {
m_cubes.reset();
m_cubes.push_back(expr_ref_vector(m)); // push empty cube
if (m_config.m_depth_splitting_only) {
if (m_config.m_depth_splitting_only || m_config.m_iterative_deepening) {
m_cubes_depth_sets.clear();
}
if (m_config.m_beam_search) {
m_cubes_pq = CubePQ();
}
m_split_atoms.reset();
smt_parallel_params sp(p.ctx.m_params);
@ -798,6 +861,7 @@ namespace smt {
m_config.m_never_cube = sp.never_cube();
m_config.m_depth_splitting_only = sp.depth_splitting_only();
m_config.m_iterative_deepening = sp.iterative_deepening();
m_config.m_beam_search = sp.beam_search();
}
void parallel::batch_manager::collect_statistics(::statistics& st) const {

27
src/smt/smt_parallel.h
View file

@ -21,6 +21,8 @@ Revision History:
#include "smt/smt_context.h"
#include <thread>
#include <map>
#include <queue>
#include <vector>
namespace smt {
@ -52,6 +54,7 @@ namespace smt {
bool m_never_cube = false;
bool m_depth_splitting_only = false;
bool m_iterative_deepening = false;
bool m_beam_search = false;
};
struct stats {
unsigned m_max_cube_depth = 0;
@ -66,6 +69,29 @@ namespace smt {
stats m_stats;
expr_ref_vector m_split_atoms; // atoms to split on
vector<expr_ref_vector> m_cubes;
struct ScoredCube {
double score;
expr_ref_vector cube;
ScoredCube(unsigned s, expr_ref_vector const& c) : score(s), cube(c) {}
};
// higher score = higher priority
struct ScoredCubeCompare {
bool operator()(ScoredCube const& a, ScoredCube const& b) const {
return a.score < b.score;
}
};
using CubePQ = std::priority_queue<
ScoredCube,
std::vector<ScoredCube>,
ScoredCubeCompare
>;
CubePQ m_cubes_pq;
std::map<unsigned, vector<expr_ref_vector>> m_cubes_depth_sets; // map<vec<cube>> contains sets of cubes, key is depth/size of cubes in the set
unsigned m_max_batch_size = 10;
unsigned m_exception_code = 0;
@ -113,6 +139,7 @@ namespace smt {
expr_ref_vector return_shared_clauses(ast_translation& g2l, unsigned& worker_limit, unsigned worker_id);
double update_avg_cube_hardness(double hardness) {
IF_VERBOSE(1, verbose_stream() << "Cube hardness: " << hardness << ", previous avg: " << m_avg_cube_hardness << ", solved cubes: " << m_solved_cube_count << "\n";);
m_avg_cube_hardness = (m_avg_cube_hardness * m_solved_cube_count + hardness) / (m_solved_cube_count + 1);
m_solved_cube_count++;
return m_avg_cube_hardness;