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add blast method for ite terms

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2013-11-04 13:33:02 -08:00
parent 53d365bc44
commit 89989627d0
10 changed files with 369 additions and 103 deletions
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2
scripts/mk_project.py
View file

@ -58,7 +58,7 @@ def init_project_def():
add_lib('muz', ['smt', 'sat', 'smt2parser', 'aig_tactic', 'qe'], 'muz/base')
add_lib('transforms', ['muz', 'hilbert'], 'muz/transforms')
add_lib('rel', ['muz', 'transforms'], 'muz/rel')
add_lib('pdr', ['muz', 'transforms', 'arith_tactics', 'smt_tactic'], 'muz/pdr')
add_lib('pdr', ['muz', 'transforms', 'arith_tactics', 'core_tactics', 'smt_tactic'], 'muz/pdr')
add_lib('clp', ['muz', 'transforms'], 'muz/clp')
add_lib('tab', ['muz', 'transforms'], 'muz/tab')
add_lib('bmc', ['muz', 'transforms'], 'muz/bmc')

3
src/muz/pdr/pdr_context.cpp
View file

@ -47,6 +47,7 @@ Notes:
#include "dl_boogie_proof.h"
#include "qe_util.h"
#include "scoped_proof.h"
#include "blast_term_ite_tactic.h"
namespace pdr {
@ -601,7 +602,7 @@ namespace pdr {
th_rewriter rw(m);
rw(fml);
if (ctx.is_dl() || ctx.is_utvpi()) {
hoist_non_bool_if(fml);
blast_term_ite(fml);
}
TRACE("pdr", tout << mk_pp(fml, m) << "\n";);
SASSERT(is_ground(fml));

63
src/muz/pdr/pdr_util.cpp
View file

@ -1030,68 +1030,6 @@ namespace pdr {
fml = m.mk_and(conjs.size(), conjs.c_ptr());
}
//
// (f (if c1 (if c2 e1 e2) e3) b c) ->
// (if c1 (if c2 (f e1 b c)
class ite_hoister {
ast_manager& m;
public:
ite_hoister(ast_manager& m): m(m) {}
br_status mk_app_core(func_decl* f, unsigned num_args, expr* const* args, expr_ref& result) {
if (m.is_ite(f)) {
return BR_FAILED;
}
for (unsigned i = 0; i < num_args; ++i) {
expr* c, *t, *e;
if (!m.is_bool(args[i]) && m.is_ite(args[i], c, t, e)) {
expr_ref e1(m), e2(m);
ptr_vector<expr> args1(num_args, args);
args1[i] = t;
e1 = m.mk_app(f, num_args, args1.c_ptr());
if (t == e) {
result = e1;
return BR_REWRITE1;
}
args1[i] = e;
e2 = m.mk_app(f, num_args, args1.c_ptr());
result = m.mk_app(f, num_args, args);
result = m.mk_ite(c, e1, e2);
return BR_REWRITE3;
}
}
return BR_FAILED;
}
};
struct ite_hoister_cfg: public default_rewriter_cfg {
ite_hoister m_r;
bool rewrite_patterns() const { return false; }
br_status reduce_app(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
return m_r.mk_app_core(f, num, args, result);
}
ite_hoister_cfg(ast_manager & m, params_ref const & p):m_r(m) {}
};
class ite_hoister_star : public rewriter_tpl<ite_hoister_cfg> {
ite_hoister_cfg m_cfg;
public:
ite_hoister_star(ast_manager & m, params_ref const & p):
rewriter_tpl<ite_hoister_cfg>(m, false, m_cfg),
m_cfg(m, p) {}
};
void hoist_non_bool_if(expr_ref& fml) {
ast_manager& m = fml.get_manager();
scoped_no_proof _sp(m);
params_ref p;
ite_hoister_star ite_rw(m, p);
expr_ref tmp(m);
ite_rw(fml, tmp);
fml = tmp;
}
class test_diff_logic {
ast_manager& m;
arith_util a;
@ -1441,7 +1379,6 @@ namespace pdr {
}
template class rewriter_tpl<pdr::ite_hoister_cfg>;
template class rewriter_tpl<pdr::arith_normalizer_cfg>;

6
src/muz/pdr/pdr_util.h
View file

@ -143,12 +143,6 @@ namespace pdr {
*/
void reduce_disequalities(model& model, unsigned threshold, expr_ref& fml);
/**
\brief hoist non-boolean if expressions.
*/
void hoist_non_bool_if(expr_ref& fml);
/**
\brief normalize coefficients in polynomials so that least coefficient is 1.
*/

44
src/opt/fu_malik.cpp
View file

@ -71,14 +71,15 @@ namespace opt {
* add at-most-one constraint with blocking
*/
bool step() {
lbool step() {
IF_VERBOSE(1, verbose_stream() << "(opt.max_sat step)\n";);
expr_ref_vector assumptions(m), block_vars(m);
for (unsigned i = 0; i < m_soft.size(); ++i) {
assumptions.push_back(m.mk_not(m_aux[i].get()));
}
lbool is_sat = s.check_sat(assumptions.size(), assumptions.c_ptr());
if (is_sat != l_false) {
return true;
return is_sat;
}
ptr_vector<expr> core;
@ -102,7 +103,7 @@ namespace opt {
s.assert_expr(m.mk_or(m_soft[i].get(), m_aux[i].get()));
}
assert_at_most_one(block_vars);
return false;
return l_false;
}
private:
@ -139,23 +140,28 @@ namespace opt {
s.push();
fu_malik fm(m, s, soft_constraints);
while (!fm.step());
// Get a list of satisfying soft_constraints
model_ref model;
s.get_model(model);
expr_ref_vector result(m);
for (unsigned i = 0; i < soft_constraints.size(); ++i) {
expr_ref val(m);
VERIFY(model->eval(soft_constraints[i].get(), val));
if (!m.is_false(val)) {
result.push_back(soft_constraints[i].get());
}
}
soft_constraints.reset();
soft_constraints.append(result);
lbool is_sat = l_true;
do {
is_sat = fm.step();
}
while (is_sat == l_false);
if (is_sat == l_true) {
// Get a list of satisfying soft_constraints
model_ref model;
s.get_model(model);
expr_ref_vector result(m);
for (unsigned i = 0; i < soft_constraints.size(); ++i) {
expr_ref val(m);
VERIFY(model->eval(soft_constraints[i].get(), val));
if (!m.is_false(val)) {
result.push_back(soft_constraints[i].get());
}
}
soft_constraints.reset();
soft_constraints.append(result);
}
s.pop(1);
}
// We are done and soft_constraints has

10
src/smt/diff_logic.h
View file

@ -935,13 +935,13 @@ public:
// Return true if there is an edge source --> target (also counting disabled edges).
// If there is such edge, return its edge_id in parameter id.
bool get_edge_id(dl_var source, dl_var target, edge_id & id) {
edge_id_vector & edges = m_out_edges[source];
typename edge_id_vector::iterator it = edges.begin();
typename edge_id_vector::iterator end = edges.end();
bool get_edge_id(dl_var source, dl_var target, edge_id & id) const {
edge_id_vector const & edges = m_out_edges[source];
typename edge_id_vector::const_iterator it = edges.begin();
typename edge_id_vector::const_iterator end = edges.end();
for (; it != end; ++it) {
id = *it;
edge & e = m_edges[id];
edge const & e = m_edges[id];
if (e.get_target() == target) {
return true;
}

5
src/smt/network_flow.h
View file

@ -93,7 +93,7 @@ namespace smt {
// Initialize the network with a feasible spanning tree
void initialize();
edge_id get_edge_id(dl_var source, dl_var target);
edge_id get_edge_id(dl_var source, dl_var target) const;
void update_potentials();
@ -112,6 +112,9 @@ namespace smt {
std::string display_spanning_tree();
bool edge_in_tree(edge_id id) const;
bool edge_in_tree(node src, node dst) const;
bool check_well_formed();
public:

80
src/smt/network_flow_def.h
View file

@ -137,7 +137,7 @@ namespace smt {
}
template<typename Ext>
edge_id network_flow<Ext>::get_edge_id(dl_var source, dl_var target) {
edge_id network_flow<Ext>::get_edge_id(dl_var source, dl_var target) const {
// m_upwards[source] decides which node is the real source
edge_id id;
VERIFY(m_upwards[source] ? m_graph.get_edge_id(source, target, id) : m_graph.get_edge_id(target, source, id));
@ -234,6 +234,7 @@ namespace smt {
m_delta = m_flows[e_id];
src = u;
tgt = m_pred[u];
SASSERT(edge_in_tree(src,tgt));
m_in_edge_dir = true;
}
}
@ -245,6 +246,7 @@ namespace smt {
m_delta = m_flows[e_id];
src = u;
tgt = m_pred[u];
SASSERT(edge_in_tree(src,tgt));
m_in_edge_dir = false;
}
}
@ -267,10 +269,12 @@ namespace smt {
node q = m_graph.get_target(m_entering_edge);
node u = m_graph.get_source(m_leaving_edge);
node v = m_graph.get_target(m_leaving_edge);
// v is parent of u so T_u does not contain root node
if (m_pred[u] == v) {
std::swap(u, v);
}
SASSERT(m_pred[v] == u);
for (node n = p; n != -1; n = m_pred[n]) {
// q should be in T_v so swap p and q
@ -285,13 +289,10 @@ namespace smt {
tout << u << ", " << v << ") leaves\n";
});
node x = m_final[p];
node y = m_thread[x];
node z = m_final[q];
// Update m_pred (for nodes in the stem from q to v)
node n = q;
node last = m_pred[v];
node last = m_pred[v]; // review: m_pred[v] == u holds, so why not 'u'?
node prev = p;
while (n != last && n != -1) {
node next = m_pred[n];
@ -303,6 +304,11 @@ namespace smt {
TRACE("network_flow", tout << pp_vector("Predecessors", m_pred, true) << pp_vector("Upwards", m_upwards););
node x = m_final[p];
node y = m_thread[x];
node z = m_final[q];
// Do this before updating data structures
node gamma_p = m_pred[m_thread[m_final[p]]];
node gamma_v = m_pred[m_thread[m_final[v]]];
@ -430,6 +436,8 @@ namespace smt {
if (!bounded) return false;
update_flows();
if (m_entering_edge != m_leaving_edge) {
SASSERT(edge_in_tree(m_leaving_edge));
SASSERT(!edge_in_tree(m_entering_edge));
m_states[m_entering_edge] = BASIS;
m_states[m_leaving_edge] = (m_flows[m_leaving_edge].is_zero()) ? LOWER : UPPER;
update_spanning_tree();
@ -494,6 +502,7 @@ namespace smt {
}
static int get_final(int root, svector<int> const & thread, svector<int> const & depth) {
// really final or should one take into account connected tree?
int n = root;
while (depth[thread[n]] > depth[root]) {
n = thread[n];
@ -501,19 +510,76 @@ namespace smt {
return n;
}
template<typename Ext>
bool network_flow<Ext>::edge_in_tree(edge_id id) const {
return m_states[id] == BASIS;
}
template<typename Ext>
bool network_flow<Ext>::edge_in_tree(node src, node dst) const {
return edge_in_tree(get_edge_id(src,dst));
}
/**
\brief Check invariants of main data-structures.
Spanning tree of m_graph + root is represented using:
svector<edge_state> m_states; edge_id |-> edge_state
svector<bool> m_upwards; node |-> bool
svector<node> m_pred; node |-> node
svector<int> m_depth; node |-> int
svector<node> m_thread; node |-> node
svector<node> m_rev_thread; node |-> node
svector<node> m_final; node |-> node
m_thread[m_rev_thread[n]] == n for each node n
Tree is determined by m_pred:
- m_pred[root] == -1
- m_pred[n] = m != n for each node n, acyclic until reaching root.
- m_depth[m_pred[n]] + 1 == m_depth[n] for each n != root
m_thread is a linked list traversing all nodes.
Furthermore, the nodes linked in m_thread follows a
depth-first traversal order.
m_final[n] is deepest most node in a sub-tree rooted at n.
*/
template<typename Ext>
bool network_flow<Ext>::check_well_formed() {
node root = m_pred.size()-1;
// Check that m_thread traverses each node.
// This gets checked using union-find as well.
svector<bool> found(m_thread.size(), false);
found[root] = true;
for (node x = m_thread[root]; x != root; x = m_thread[x]) {
found[x] = true;
}
for (unsigned i = 0; i < found.size(); ++i) {
SASSERT(found[i]);
}
// m_pred is acyclic, and points to root.
SASSERT(m_pred[root] == -1);
SASSERT(m_depth[root] == 0);
for (node i = 0; i < root; ++i) {
SASSERT(m_depth[m_pred[i]] < m_depth[i]);
}
// m_upwards show correct direction
for (unsigned i = 0; i < m_upwards.size(); ++i) {
node p = m_pred[i];
edge_id id;
SASSERT(m_upwards[i] == m_graph.get_edge_id(i, p, id));
SASSERT(!m_upwards[i] || m_graph.get_edge_id(i, p, id));
}
// m_depth[x] denotes distance from x to the root node
for (node x = m_thread[root]; x != root; x = m_thread[x]) {
SASSERT(m_depth[x] > 0);
SASSERT(m_depth[x] == m_depth[m_pred[x]] + 1);
}
@ -540,7 +606,7 @@ namespace smt {
// All nodes belong to the same spanning tree
for (unsigned i = 0; i < roots.size(); ++i) {
SASSERT(i == 0 ? roots[i] + roots.size() == 0 : roots[i] == 0);
SASSERT(roots[i] + roots.size() == 0 || roots[i] >= 0);
}
// m_flows are zero on non-basic edges

221
src/tactic/core/blast_term_ite_tactic.cpp Normal file
View file

@ -0,0 +1,221 @@
/*++
Copyright (c) 2013 Microsoft Corporation
Module Name:
blast_term_ite_tactic.cpp
Abstract:
Blast term if-then-else by hoisting them up.
Author:
Nikolaj Bjorner (nbjorner) 2013-11-4
Notes:
--*/
#include"tactical.h"
#include"defined_names.h"
#include"rewriter_def.h"
#include"filter_model_converter.h"
#include"cooperate.h"
#include"scoped_proof.h"
//
// (f (if c1 (if c2 e1 e2) e3) b c) ->
// (if c1 (if c2 (f e1 b c)
//
class blast_term_ite_tactic : public tactic {
struct rw_cfg : public default_rewriter_cfg {
ast_manager& m;
unsigned long long m_max_memory; // in bytes
unsigned m_num_fresh; // number of expansions
rw_cfg(ast_manager & _m, params_ref const & p):
m(_m),
m_num_fresh(0) {
updt_params(p);
}
void updt_params(params_ref const & p) {
m_max_memory = megabytes_to_bytes(p.get_uint("max_memory", UINT_MAX));
}
bool max_steps_exceeded(unsigned num_steps) const {
cooperate("blast term ite");
if (memory::get_allocation_size() > m_max_memory)
throw tactic_exception(TACTIC_MAX_MEMORY_MSG);
return false;
}
br_status mk_app_core(func_decl* f, unsigned num_args, expr* const* args, expr_ref& result) {
if (m.is_ite(f)) {
return BR_FAILED;
}
for (unsigned i = 0; i < num_args; ++i) {
expr* c, *t, *e;
if (!m.is_bool(args[i]) && m.is_ite(args[i], c, t, e)) {
expr_ref e1(m), e2(m);
ptr_vector<expr> args1(num_args, args);
args1[i] = t;
++m_num_fresh;
e1 = m.mk_app(f, num_args, args1.c_ptr());
if (t == e) {
result = e1;
return BR_REWRITE1;
}
args1[i] = e;
e2 = m.mk_app(f, num_args, args1.c_ptr());
result = m.mk_app(f, num_args, args);
result = m.mk_ite(c, e1, e2);
return BR_REWRITE3;
}
}
return BR_FAILED;
}
bool rewrite_patterns() const { return false; }
br_status reduce_app(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
return mk_app_core(f, num, args, result);
}
};
struct rw : public rewriter_tpl<rw_cfg> {
rw_cfg m_cfg;
rw(ast_manager & m, params_ref const & p):
rewriter_tpl<rw_cfg>(m, m.proofs_enabled(), m_cfg),
m_cfg(m, p) {
}
};
struct imp {
ast_manager & m;
rw m_rw;
imp(ast_manager & _m, params_ref const & p):
m(_m),
m_rw(m, p) {
}
void set_cancel(bool f) {
m_rw.set_cancel(f);
}
void updt_params(params_ref const & p) {
m_rw.cfg().updt_params(p);
}
void operator()(goal_ref const & g,
goal_ref_buffer & result,
model_converter_ref & mc,
proof_converter_ref & pc,
expr_dependency_ref & core) {
SASSERT(g->is_well_sorted());
mc = 0; pc = 0; core = 0;
tactic_report report("blast-term-ite", *g);
bool produce_proofs = g->proofs_enabled();
expr_ref new_curr(m);
proof_ref new_pr(m);
unsigned size = g->size();
for (unsigned idx = 0; idx < size; idx++) {
expr * curr = g->form(idx);
m_rw(curr, new_curr, new_pr);
if (produce_proofs) {
proof * pr = g->pr(idx);
new_pr = m.mk_modus_ponens(pr, new_pr);
}
g->update(idx, new_curr, new_pr, g->dep(idx));
}
report_tactic_progress(":blast-term-ite-consts", m_rw.m_cfg.m_num_fresh);
g->inc_depth();
result.push_back(g.get());
TRACE("blast_term_ite", g->display(tout););
SASSERT(g->is_well_sorted());
}
};
imp * m_imp;
params_ref m_params;
public:
blast_term_ite_tactic(ast_manager & m, params_ref const & p):
m_params(p) {
m_imp = alloc(imp, m, p);
}
virtual tactic * translate(ast_manager & m) {
return alloc(blast_term_ite_tactic, m, m_params);
}
virtual ~blast_term_ite_tactic() {
dealloc(m_imp);
}
virtual void updt_params(params_ref const & p) {
m_params = p;
m_imp->m_rw.cfg().updt_params(p);
}
virtual void collect_param_descrs(param_descrs & r) {
insert_max_memory(r);
insert_max_steps(r);
r.insert("max_args", CPK_UINT,
"(default: 128) maximum number of arguments (per application) that will be considered by the greedy (quadratic) heuristic.");
}
virtual void operator()(goal_ref const & in,
goal_ref_buffer & result,
model_converter_ref & mc,
proof_converter_ref & pc,
expr_dependency_ref & core) {
(*m_imp)(in, result, mc, pc, core);
}
virtual void cleanup() {
ast_manager & m = m_imp->m;
imp * d = m_imp;
#pragma omp critical (tactic_cancel)
{
m_imp = 0;
}
dealloc(d);
d = alloc(imp, m, m_params);
#pragma omp critical (tactic_cancel)
{
m_imp = d;
}
}
virtual void set_cancel(bool f) {
if (m_imp)
m_imp->set_cancel(f);
}
static void blast_term_ite(expr_ref& fml) {
ast_manager& m = fml.get_manager();
scoped_no_proof _sp(m);
params_ref p;
rw ite_rw(m, p);
expr_ref tmp(m);
ite_rw(fml, tmp);
fml = tmp;
}
};
tactic * mk_blast_term_ite_tactic(ast_manager & m, params_ref const & p) {
return clean(alloc(blast_term_ite_tactic, m, p));
}
void blast_term_ite(expr_ref& fml) {
blast_term_ite_tactic::blast_term_ite(fml);
}

38
src/tactic/core/blast_term_ite_tactic.h Normal file
View file

@ -0,0 +1,38 @@
/*++
Copyright (c) 2013 Microsoft Corporation
Module Name:
blast_term_ite_tactic.h
Abstract:
Blast term if-then-else by hoisting them up.
This is expensive but useful in some cases, such as
for enforcing constraints being in difference logic.
Use elim-term-ite elsewhere when possible.
Author:
Nikolaj Bjorner (nbjorner) 2013-11-4
Notes:
--*/
#ifndef _BLAST_TERM_ITE_TACTIC_H_
#define _BLAST_TERM_ITE_TACTIC_H_
#include"params.h"
class ast_manager;
class tactic;
tactic * mk_blast_term_ite_tactic(ast_manager & m, params_ref const & p = params_ref());
/*
ADD_TACTIC("blast-term-ite", "blast term if-then-else by hoisting them.", "mk_blast_term_ite_tactic(m, p)")
*/
void blast_term_ite(expr_ref& fml);
#endif