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hoist macro-replacer as shared utility, update eliminate-predicates and model reconstruction

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This commit is contained in:
Nikolaj Bjorner 2022-11-24 19:45:51 +07:00
parent 5fe2ff84e9
commit caf204ab95
6 changed files with 367 additions and 131 deletions
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1
src/ast/rewriter/CMakeLists.txt
View file

@ -25,6 +25,7 @@ z3_add_component(rewriter
hoist_rewriter.cpp
inj_axiom.cpp
label_rewriter.cpp
macro_replacer.cpp
maximize_ac_sharing.cpp
mk_simplified_app.cpp
pb_rewriter.cpp

142
src/ast/rewriter/macro_replacer.cpp Normal file
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@ -0,0 +1,142 @@
/*++
Copyright (c) 2022 Microsoft Corporation
Module Name:
macro_replacer.cpp
Abstract:
Abstract (functor) for applying macro replacement.
Author:
Nikolaj Bjorner (nbjorner) 2022-11-24
Notes:
--*/
#include "ast/rewriter/macro_replacer.h"
#include "ast/rewriter/rewriter_def.h"
#include "ast/rewriter/var_subst.h"
/**
* Rewriting formulas using macro definitions.
*/
struct macro_replacer::macro_replacer_cfg : public default_rewriter_cfg {
ast_manager& m;
macro_replacer& ep;
expr_dependency_ref& m_used_macro_dependencies;
expr_ref_vector m_trail;
macro_replacer_cfg(ast_manager& m, macro_replacer& ep, expr_dependency_ref& deps) :
m(m),
ep(ep),
m_used_macro_dependencies(deps),
m_trail(m)
{}
bool rewrite_patterns() const { return false; }
bool flat_assoc(func_decl* f) const { return false; }
br_status reduce_app(func_decl* f, unsigned num, expr* const* args, expr_ref& result, proof_ref& result_pr) {
result_pr = nullptr;
return BR_FAILED;
}
/**
* adapted from macro_manager.cpp
* Perhaps hoist and combine?
*/
bool reduce_quantifier(quantifier* old_q,
expr* new_body,
expr* const* new_patterns,
expr* const* new_no_patterns,
expr_ref& result,
proof_ref& result_pr) {
bool erase_patterns = false;
for (unsigned i = 0; !erase_patterns && i < old_q->get_num_patterns(); i++)
if (old_q->get_pattern(i) != new_patterns[i])
erase_patterns = true;
for (unsigned i = 0; !erase_patterns && i < old_q->get_num_no_patterns(); i++)
if (old_q->get_no_pattern(i) != new_no_patterns[i])
erase_patterns = true;
if (erase_patterns)
result = m.update_quantifier(old_q, 0, nullptr, 0, nullptr, new_body);
if (erase_patterns && m.proofs_enabled())
result_pr = m.mk_rewrite(old_q, result);
return erase_patterns;
}
bool get_subst(expr* _n, expr*& r, proof*& p) {
if (!is_app(_n))
return false;
p = nullptr;
app* n = to_app(_n);
quantifier* q = nullptr;
func_decl* d = n->get_decl(), * d2 = nullptr;
app_ref head(m);
expr_ref def(m);
expr_dependency_ref dep(m);
if (ep.has_macro(d, head, def, dep)) {
unsigned num = head->get_num_args();
ptr_buffer<expr> subst_args;
subst_args.resize(num, 0);
for (unsigned i = 0; i < num; i++) {
var* v = to_var(head->get_arg(i));
VERIFY(v->get_idx() < num);
unsigned nidx = num - v->get_idx() - 1;
SASSERT(!subst_args[nidx]);
subst_args[nidx] = n->get_arg(i);
}
var_subst s(m);
expr_ref rr = s(def, num, subst_args.data());
r = rr;
m_trail.push_back(rr);
m_used_macro_dependencies = m.mk_join(m_used_macro_dependencies, dep);
// skip proof terms for simplifiers
return true;
}
return false;
}
};
struct macro_replacer::macro_replacer_rw : public rewriter_tpl<macro_replacer::macro_replacer_cfg> {
macro_replacer::macro_replacer_cfg m_cfg;
macro_replacer_rw(ast_manager& m, macro_replacer& ep, expr_dependency_ref& deps) :
rewriter_tpl<macro_replacer::macro_replacer_cfg>(m, false, m_cfg),
m_cfg(m, ep, deps)
{}
};
void macro_replacer::insert(app* head, expr* def, expr_dependency* dep) {
func_decl* f = head->get_decl();
m_trail.push_back(head);
m_trail.push_back(def);
m_deps.push_back(dep);
m_map.insert(f, std::tuple(head, def, dep));
}
void macro_replacer::operator()(expr* t, expr_ref& result, expr_dependency_ref& dep) {
macro_replacer_rw exp(m, *this, dep);
exp(t, result);
}
bool macro_replacer::has_macro(func_decl* f, app_ref& head, expr_ref& def, expr_dependency_ref& dep) {
std::tuple<app*,expr*,expr_dependency*> v;
if (!m_map.find(f, v))
return false;
auto const& [h, d, dp] = v;
head = h;
def = d;
dep = dp;
return true;
}

44
src/ast/rewriter/macro_replacer.h Normal file
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@ -0,0 +1,44 @@
/*++
Copyright (c) 2022 Microsoft Corporation
Module Name:
macro_replacer.h
Abstract:
Abstract (functor) for applying macro replacement.
Author:
Nikolaj Bjorner (nbjorner) 2022-11-24
Notes:
--*/
#pragma once
#include "ast/ast.h"
#include "util/obj_hashtable.h"
class macro_replacer {
ast_manager& m;
ast_ref_vector m_trail;
expr_dependency_ref_vector m_deps;
obj_map<func_decl, std::tuple<app*, expr*, expr_dependency*>> m_map;
struct macro_replacer_cfg;
struct macro_replacer_rw;
public:
macro_replacer(ast_manager& m): m(m), m_trail(m), m_deps(m) {}
void insert(app* head, expr* def, expr_dependency* dep);
void operator()(expr* t, expr_ref& result, expr_dependency_ref& dep);
void operator()(expr* t, expr_ref & result) { expr_dependency_ref dep(m); (*this)(t, result, dep); }
void operator()(expr_ref & t) { expr_ref s(t, m); (*this)(s, t); }
bool has_macro(func_decl* f, app_ref& head, expr_ref& def, expr_dependency_ref& d);
};

268
src/ast/simplifiers/eliminate_predicates.cpp
View file

@ -58,105 +58,7 @@ forbidden from macros vs forbidden from elimination
#include "ast/rewriter/rewriter_def.h"
#include "ast/simplifiers/eliminate_predicates.h"
#include "ast/rewriter/th_rewriter.h"
/**
* Rewriting formulas using macro definitions.
*/
struct eliminate_predicates::macro_expander_cfg : public default_rewriter_cfg {
ast_manager& m;
eliminate_predicates& ep;
expr_dependency_ref& m_used_macro_dependencies;
expr_ref_vector m_trail;
macro_expander_cfg(ast_manager& m, eliminate_predicates& ep, expr_dependency_ref& deps) :
m(m),
ep(ep),
m_used_macro_dependencies(deps),
m_trail(m)
{}
bool rewrite_patterns() const { return false; }
bool flat_assoc(func_decl* f) const { return false; }
br_status reduce_app(func_decl* f, unsigned num, expr* const* args, expr_ref& result, proof_ref& result_pr) {
result_pr = nullptr;
return BR_FAILED;
}
/**
* adapted from macro_manager.cpp
* Perhaps hoist and combine?
*/
bool reduce_quantifier(quantifier* old_q,
expr* new_body,
expr* const* new_patterns,
expr* const* new_no_patterns,
expr_ref& result,
proof_ref& result_pr) {
bool erase_patterns = false;
for (unsigned i = 0; !erase_patterns && i < old_q->get_num_patterns(); i++)
if (old_q->get_pattern(i) != new_patterns[i])
erase_patterns = true;
for (unsigned i = 0; !erase_patterns && i < old_q->get_num_no_patterns(); i++)
if (old_q->get_no_pattern(i) != new_no_patterns[i])
erase_patterns = true;
if (erase_patterns)
result = m.update_quantifier(old_q, 0, nullptr, 0, nullptr, new_body);
if (erase_patterns && m.proofs_enabled())
result_pr = m.mk_rewrite(old_q, result);
return erase_patterns;
}
bool get_subst(expr* _n, expr*& r, proof*& p) {
if (!is_app(_n))
return false;
p = nullptr;
app* n = to_app(_n);
quantifier* q = nullptr;
func_decl* d = n->get_decl(), * d2 = nullptr;
app_ref head(m);
expr_ref def(m);
expr_dependency_ref dep(m);
if (ep.has_macro(d, head, def, dep)) {
unsigned num = head->get_num_args();
ptr_buffer<expr> subst_args;
subst_args.resize(num, 0);
// TODO: we can exploit that variables occur in "non-standard" order
// that is in order (:var 0) (:var 1) (:var 2)
// then substitution just takes n->get_args() instead of this renaming.
for (unsigned i = 0; i < num; i++) {
var* v = to_var(head->get_arg(i));
VERIFY(v->get_idx() < num);
unsigned nidx = num - v->get_idx() - 1;
SASSERT(subst_args[nidx] == 0);
subst_args[nidx] = n->get_arg(i);
}
var_subst s(m);
expr_ref rr = s(def, num, subst_args.data());
r = rr;
m_trail.push_back(rr);
m_used_macro_dependencies = m.mk_join(m_used_macro_dependencies, dep);
// skip proof terms for simplifiers
return true;
}
return false;
}
};
struct eliminate_predicates::macro_expander_rw : public rewriter_tpl<eliminate_predicates::macro_expander_cfg> {
eliminate_predicates::macro_expander_cfg m_cfg;
macro_expander_rw(ast_manager& m, eliminate_predicates& ep, expr_dependency_ref& deps) :
rewriter_tpl<eliminate_predicates::macro_expander_cfg>(m, false, m_cfg),
m_cfg(m, ep, deps)
{}
};
#include "ast/rewriter/macro_replacer.h"
std::ostream& eliminate_predicates::clause::display(std::ostream& out) const {
@ -200,10 +102,18 @@ void eliminate_predicates::add_use_list(clause& cl) {
* Check that all arguments are distinct variables that are bound.
*/
bool eliminate_predicates::can_be_macro_head(app* head, unsigned num_bound) {
uint_set indices;
if (head->get_decl()->is_associative())
bool eliminate_predicates::can_be_macro_head(expr* _head, unsigned num_bound) {
if (!is_app(_head))
return false;
app* head = to_app(_head);
func_decl* f = head->get_decl();
if (m_disable_macro.is_marked(f))
return false;
if (m_is_macro.is_marked(f))
return false;
if (f->is_associative())
return false;
uint_set indices;
for (expr* arg : *head) {
if (!is_var(arg))
return false;
@ -315,7 +225,7 @@ bool eliminate_predicates::is_macro_safe(expr* e) {
return true;
}
void eliminate_predicates::insert_macro(app_ref& head, expr_ref& def, expr_dependency_ref& dep) {
void eliminate_predicates::insert_macro(app* head, expr* def, expr_dependency* dep) {
unsigned num = head->get_num_args();
ptr_buffer<expr> vars, subst_args;
subst_args.resize(num, nullptr);
@ -330,13 +240,17 @@ void eliminate_predicates::insert_macro(app_ref& head, expr_ref& def, expr_depen
vars[i] = w;
}
var_subst sub(m, false);
def = sub(def, subst_args.size(), subst_args.data());
head = m.mk_app(head->get_decl(), vars);
auto* info = alloc(macro_def, head, def, dep);
app_ref _head(m);
expr_ref _def(m);
expr_dependency_ref _dep(dep, m);
_def = sub(def, subst_args.size(), subst_args.data());
_head = m.mk_app(head->get_decl(), vars);
auto* info = alloc(macro_def, _head, _def, _dep);
m_macros.insert(head->get_decl(), info);
m_fmls.model_trail().push(head->get_decl(), def, {});
m_fmls.model_trail().push(head->get_decl(), _def, _dep, {}); // augment with definition for head
m_is_macro.mark(head->get_decl(), true);
TRACE("elim_predicates", tout << "insert " << head << " " << def << "\n");
TRACE("elim_predicates", tout << "insert " << _head << " " << _def << "\n");
++m_stats.m_num_macros;
}
@ -348,20 +262,124 @@ void eliminate_predicates::try_resolve_definition(func_decl* p) {
insert_macro(head, def, dep);
}
bool eliminate_predicates::has_macro(func_decl* p, app_ref& head, expr_ref& def, expr_dependency_ref& dep) {
macro_def* md = nullptr;
if (m_macros.find(p, md)) {
head = md->m_head;
def = md->m_def;
dep = md->m_dep;
return true;
/**
* Port of macros handled by macro_finder/macro_util
*/
void eliminate_predicates::try_find_macro(clause& cl) {
if (!cl.m_alive)
return;
expr* x, * y;
auto can_be_def = [&](expr* _x, expr* y) {
if (!is_app(_x))
return false;
app* x = to_app(_x);
return
can_be_macro_head(x, cl.m_bound.size()) &&
is_macro_safe(y) &&
x->get_num_args() == cl.m_bound.size() &&
!occurs(x->get_decl(), y);
};
// (= (f x) t)
if (cl.is_unit() && !cl.sign(0) && m.is_eq(cl.atom(0), x, y)) {
if (can_be_def(x, y)) {
insert_macro(to_app(x), y, cl.m_dep);
cl.m_alive = false;
return;
}
if (can_be_def(y, x)) {
insert_macro(to_app(y), x, cl.m_dep);
cl.m_alive = false;
return;
}
}
return false;
// not (= (p x) t) -> (p x) = (not t)
if (cl.is_unit() && cl.sign(0) && m.is_iff(cl.atom(0), x, y)) {
if (can_be_def(x, y)) {
insert_macro(to_app(x), m.mk_not(y), cl.m_dep);
cl.m_alive = false;
return;
}
if (can_be_def(y, x)) {
insert_macro(to_app(y), m.mk_not(x), cl.m_dep);
cl.m_alive = false;
return;
}
}
// pseudo-macros:
// (iff (= (f x) t) cond)
// rewrites to (f x) = (if cond t else (k x))
// add clause (not (= (k x) t))
//
// we will call them _conditioned_ macros
auto can_be_conditioned = [&](expr* f, expr* t, expr* cond) {
return
can_be_def(f, t) &&
!occurs(to_app(f)->get_decl(), cond) &&
is_macro_safe(cond);
};
auto make_conditioned = [&](app* f, expr* t, expr* cond) {
func_decl* df = f->get_decl();
app_ref def(m), k(m), fml(m);
func_decl_ref fn(m);
fn = m.mk_fresh_func_decl(df->get_arity(), df->get_domain(), df->get_range());
m_fmls.model_trail().push(fn); // hide definition of fn
k = m.mk_app(fn, f->get_num_args(), f->get_args());
def = m.mk_ite(cond, t, k);
insert_macro(f, def, cl.m_dep);
cl.m_alive = false;
fml = m.mk_not(m.mk_eq(k, t));
init_clause(fml, cl.m_dep, UINT_MAX);
};
if (cl.is_unit() && !cl.sign(0) && m.is_iff(cl.atom(0), x, y)) {
expr* z, * u;
if (m.is_eq(x, z, u) && can_be_conditioned(z, u, y)) {
make_conditioned(to_app(z), u, y);
return;
}
if (m.is_eq(x, u, z) && can_be_conditioned(z, u, y)) {
make_conditioned(to_app(z), u, y);
return;
}
if (m.is_eq(y, z, u) && can_be_conditioned(z, u, x)) {
make_conditioned(to_app(z), u, x);
return;
}
if (m.is_eq(y, u, z) && can_be_conditioned(z, u, x)) {
make_conditioned(to_app(z), u, x);
return;
}
}
//
// other macros handled by macro_finder:
//
// arithmetic/bit-vectors
// (= (+ (f x) s) t)
// becomes (= (f x) (- t s))
//
// macro_finder also has:
// (>= (+ (f x) s) t)
// becomes (= (f x) (- t s (k x))
// add (>= (k x) 0)
// why is this a real improvement?
//
// To review: quasi-macros
// (= (f x y (+ x y)) s), where x y are all bound variables.
// then ...?
}
void eliminate_predicates::find_definitions() {
for (auto* p : m_predicates)
try_resolve_definition(p);
for (auto* cl : m_clauses)
try_find_macro(*cl);
}
void eliminate_predicates::rewrite(expr_ref& t) {
@ -374,13 +392,16 @@ void eliminate_predicates::reduce_definitions() {
if (m_macros.empty())
return;
macro_replacer macro_expander(m);
for (auto const& [k, v] : m_macros)
macro_expander.insert(v->m_head, v->m_def, v->m_dep);
for (unsigned i = m_qhead; i < m_fmls.size(); ++i) {
auto [f, d] = m_fmls[i]();
expr_ref fml(f, m), new_fml(m);
expr_dependency_ref dep(m);
while (true) {
macro_expander_rw macro_expander(m, *this, dep);
macro_expander(fml, new_fml);
macro_expander(fml, new_fml, dep);
if (new_fml == fml)
break;
rewrite(new_fml);
@ -464,6 +485,7 @@ void eliminate_predicates::try_resolve(func_decl* p) {
void eliminate_predicates::update_model(func_decl* p) {
expr_ref_vector fmls(m);
expr_ref def(m);
expr_dependency_ref dep(m);
unsigned numpos = 0, numneg = 0;
vector<dependent_expr> deleted;
for (auto* pos : m_use_list.get(p, false))
@ -475,19 +497,23 @@ void eliminate_predicates::update_model(func_decl* p) {
if (numpos < numneg) {
for (auto* pos : m_use_list.get(p, false))
if (pos->m_alive)
if (pos->m_alive) {
fmls.push_back(create_residue_formula(p, *pos));
dep = m.mk_join(dep, pos->m_dep);
}
def = mk_or(fmls);
}
else {
for (auto* neg : m_use_list.get(p, true))
if (neg->m_alive)
if (neg->m_alive) {
fmls.push_back(mk_not(m, create_residue_formula(p, *neg)));
dep = m.mk_join(dep, neg->m_dep);
}
def = mk_and(fmls);
}
rewrite(def);
m_fmls.model_trail().push(p, def, deleted);
m_fmls.model_trail().push(p, def, dep, deleted);
}
/**

30
src/ast/simplifiers/model_reconstruction_trail.cpp
View file

@ -13,6 +13,7 @@ Author:
#include "ast/for_each_expr.h"
#include "ast/rewriter/macro_replacer.h"
#include "ast/simplifiers/model_reconstruction_trail.h"
#include "ast/converters/generic_model_converter.h"
@ -32,11 +33,10 @@ void model_reconstruction_trail::replay(dependent_expr const& d, vector<dependen
if (t->is_hide())
continue;
// updates that have no intersections with current variables are skipped
if (!t->intersects(free_vars))
continue;
continue;
// loose entries that intersect with free vars are deleted from the trail
// and their removed formulas are added to the resulting constraints.
@ -49,8 +49,29 @@ void model_reconstruction_trail::replay(dependent_expr const& d, vector<dependen
continue;
}
if (t->is_def())
NOT_IMPLEMENTED_YET();
if (t->is_def()) {
macro_replacer mrp(m);
app_ref head(m);
func_decl* d = t->m_decl;
ptr_buffer<expr> args;
for (unsigned i = 0; i < d->get_arity(); ++i)
args.push_back(m.mk_var(i, d->get_domain(i)));
head = m.mk_app(d, args);
mrp.insert(head, t->m_def, t->m_dep);
dependent_expr de(m, t->m_def, t->m_dep);
add_vars(de, free_vars);
for (auto& d : added) {
auto [f, dep1] = d();
expr_ref g(m);
expr_dependency_ref dep2(m);
mrp(f, g, dep2);
d = dependent_expr(m, g, m.mk_join(dep1, dep2));
}
continue;
}
rp->set_substitution(t->m_subst.get());
// rigid entries:
@ -59,6 +80,7 @@ void model_reconstruction_trail::replay(dependent_expr const& d, vector<dependen
auto [f, dep1] = d();
auto [g, dep2] = rp->replace_with_dep(f);
d = dependent_expr(m, g, m.mk_join(dep1, dep2));
add_vars(d, free_vars);
}
}
}

13
src/ast/simplifiers/model_reconstruction_trail.h
View file

@ -37,16 +37,17 @@ class model_reconstruction_trail {
vector<dependent_expr> m_removed;
func_decl_ref m_decl;
expr_ref m_def;
expr_dependency_ref m_dep;
bool m_active = true;
entry(ast_manager& m, expr_substitution* s, vector<dependent_expr> const& rem) :
m_subst(s), m_removed(rem), m_decl(m), m_def(m) {}
m_subst(s), m_removed(rem), m_decl(m), m_def(m), m_dep(m) {}
entry(ast_manager& m, func_decl* h) : m_decl(h, m), m_def(m) {}
entry(ast_manager& m, func_decl* h) : m_decl(h, m), m_def(m), m_dep(m) {}
entry(ast_manager& m, func_decl* f, expr* def, vector<dependent_expr> const& rem) :
m_decl(f, m), m_def(def, m), m_removed(rem) {}
entry(ast_manager& m, func_decl* f, expr* def, expr_dependency* dep, vector<dependent_expr> const& rem) :
m_decl(f, m), m_def(def, m), m_removed(rem), m_dep(dep, m) {}
bool is_loose() const { return !m_removed.empty(); }
@ -109,8 +110,8 @@ public:
/**
* add definition
*/
void push(func_decl* f, expr* def, vector<dependent_expr> const& removed) {
m_trail.push_back(alloc(entry, m, f, def, removed));
void push(func_decl* f, expr* def, expr_dependency* dep, vector<dependent_expr> const& removed) {
m_trail.push_back(alloc(entry, m, f, def, dep, removed));
m_trail_stack.push(push_back_vector(m_trail));
}