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Cache results of the normalizer. Add example that demonstrates the exponential performance improvement.

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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
This commit is contained in:
Leonardo de Moura 2013-08-14 23:18:50 -07:00
parent 984c4149fa
commit 2d74ff5fe0
4 changed files with 90 additions and 28 deletions
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93
src/kernel/normalize.cpp
View file

@ -9,6 +9,7 @@ Author: Leonardo de Moura
#include "expr.h"
#include "context.h"
#include "environment.h"
#include "scoped_map.h"
#include "builtin.h"
#include "free_vars.h"
#include "list.h"
@ -28,6 +29,7 @@ class svalue {
expr m_expr;
value_stack m_ctx;
public:
svalue() {}
explicit svalue(expr const & e): m_kind(svalue_kind::Expr), m_expr(e) {}
explicit svalue(unsigned k): m_kind(svalue_kind::BoundedVar), m_bvar(k) {}
svalue(expr const & e, value_stack const & c):m_kind(svalue_kind::Closure), m_expr(e), m_ctx(c) { lean_assert(is_lambda(e)); }
@ -52,8 +54,11 @@ value_stack extend(value_stack const & s, svalue const & v) { return cons(v, s);
/** \brief Expression normalizer. */
class normalize_fn {
typedef scoped_map<expr, svalue, expr_hash, expr_eqp> cache;
environment const & m_env;
context const & m_ctx;
cache m_cache;
svalue lookup(value_stack const & s, unsigned i, unsigned k) {
unsigned j = i;
@ -127,20 +132,33 @@ class normalize_fn {
/** \brief Normalize the expression \c a in a context composed of stack \c s and \c k binders. */
svalue normalize(expr const & a, value_stack const & s, unsigned k) {
lean_trace("normalize", tout << "Normalize, k: " << k << "\n" << a << "\n";);
bool shared = false;
if (is_shared(a)) {
shared = true;
auto it = m_cache.find(a);
if (it != m_cache.end())
return it->second;
}
svalue r;
switch (a.kind()) {
case expr_kind::Var:
return lookup(s, var_idx(a), k);
r = lookup(s, var_idx(a), k);
break;
case expr_kind::Constant: {
named_object const & obj = m_env.get_object(const_name(a));
if (obj.is_definition() && !obj.is_opaque()) {
return normalize(obj.get_value(), value_stack(), 0);
r = normalize(obj.get_value(), value_stack(), 0);
}
else {
return svalue(a);
r = svalue(a);
}
break;
}
case expr_kind::Type: case expr_kind::Value:
return svalue(a);
r = svalue(a);
break;
case expr_kind::App: {
svalue f = normalize(arg(a, 0), s, k);
unsigned i = 1;
@ -150,10 +168,15 @@ class normalize_fn {
// beta reduction
expr const & fv = to_expr(f);
lean_trace("normalize", tout << "beta reduction...\n" << fv << "\n";);
value_stack new_s = extend(stack_of(f), normalize(arg(a, i), s, k));
f = normalize(abst_body(fv), new_s, k);
if (i == n - 1)
return f;
{
cache::mk_scope sc(m_cache);
value_stack new_s = extend(stack_of(f), normalize(arg(a, i), s, k));
f = normalize(abst_body(fv), new_s, k);
}
if (i == n - 1) {
r = f;
break;
}
i++;
} else {
buffer<expr> new_args;
@ -162,37 +185,55 @@ class normalize_fn {
for (; i < n; i++)
new_args.push_back(reify(normalize(arg(a, i), s, k), k));
if (is_value(new_f)) {
expr r;
if (to_value(new_f).normalize(new_args.size(), new_args.data(), r))
return svalue(r);
expr m;
if (to_value(new_f).normalize(new_args.size(), new_args.data(), m)) {
r = svalue(m);
break;
}
}
return svalue(mk_app(new_args.size(), new_args.data()));
r = svalue(mk_app(new_args.size(), new_args.data()));
break;
}
}
break;
}
case expr_kind::Eq: {
expr new_l = reify(normalize(eq_lhs(a), s, k), k);
expr new_r = reify(normalize(eq_rhs(a), s, k), k);
if (new_l == new_r) {
return svalue(mk_bool_value(true));
} else if (is_value(new_l) && is_value(new_r)) {
return svalue(mk_bool_value(false));
expr new_lhs = reify(normalize(eq_lhs(a), s, k), k);
expr new_rhs = reify(normalize(eq_rhs(a), s, k), k);
if (new_lhs == new_rhs) {
r = svalue(mk_bool_value(true));
} else if (is_value(new_lhs) && is_value(new_rhs)) {
r = svalue(mk_bool_value(false));
} else {
return svalue(mk_eq(new_l, new_r));
r = svalue(mk_eq(new_lhs, new_rhs));
}
break;
}
case expr_kind::Lambda:
return svalue(a, s);
r = svalue(a, s);
break;
case expr_kind::Pi: {
expr new_t = reify(normalize(abst_domain(a), s, k), k);
expr new_b = reify(normalize(abst_body(a), extend(s, svalue(k)), k+1), k+1);
return svalue(mk_pi(abst_name(a), new_t, new_b));
expr new_b;
{
cache::mk_scope sc(m_cache);
new_b = reify(normalize(abst_body(a), extend(s, svalue(k)), k+1), k+1);
}
r = svalue(mk_pi(abst_name(a), new_t, new_b));
break;
}
case expr_kind::Let:
return normalize(let_body(a), extend(s, normalize(let_value(a), s, k)), k+1);
case expr_kind::Let: {
svalue v = normalize(let_value(a), s, k);
{
cache::mk_scope sc(m_cache);
r = normalize(let_body(a), extend(s, v), k+1);
}
break;
}}
if (shared) {
m_cache.insert(a, r);
}
lean_unreachable();
return svalue(a);
return r;
}
public:

2
src/kernel/type_check.cpp
View file

@ -125,7 +125,7 @@ struct infer_type_fn {
lean_trace("type_check", tout << "infer type\n" << e << "\n" << ctx << "\n";);
bool shared = false;
if (true && is_shared(e)) {
if (is_shared(e)) {
shared = true;
auto it = m_cache.find(e);
if (it != m_cache.end())

22
src/tests/kernel/type_check.cpp
View file

@ -184,6 +184,27 @@ static void tst10() {
std::cout << env.get_object("simp_eq").pp(env) << "\n";
}
static void tst11() {
environment env = mk_toplevel();
env.add_var("f", Int >> (Int >> Int));
env.add_var("a", Int);
unsigned n = 1000;
expr f = Const("f");
expr a = Const("a");
expr t1 = f(a,a);
expr b = Const("a");
expr t2 = f(a,a);
expr t3 = f(b,b);
for (unsigned i = 0; i < n; i++) {
t1 = f(t1,t1);
t2 = mk_let("x", t2, f(Var(0), Var(0)));
t3 = f(t3,t3);
}
lean_assert(t1 != t2);
env.add_theorem("eqs1", Eq(t1,t2), Refl(Int, t1));
env.add_theorem("eqs2", Eq(t1,t3), Refl(Int, t1));
}
int main() {
tst1();
tst2();
@ -195,5 +216,6 @@ int main() {
tst8();
tst9();
tst10();
tst11();
return has_violations() ? 1 : 0;
}

1
src/util/scoped_map.h
View file

@ -98,7 +98,6 @@ public:
m_actions.push_back(std::make_pair(action_kind::Replace, *it));
it->second = v;
}
lean_assert(m_map.find(k)->second == v);
}
void insert(value_type const & p) {