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fix(library/type_context): failure cache

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The new regression test exposes the problem being fixed.
This commit is contained in:
Leonardo de Moura 2016-12-13 07:48:52 -08:00
parent fc7410633f
commit b2c1ea6fdb
2 changed files with 20 additions and 5 deletions
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12
src/library/type_context.cpp
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@ -212,7 +212,8 @@ void type_context::cache_failure(expr const & t, expr const & s) {
}
bool type_context::is_cached_failure(expr const & t, expr const & s) {
type_context_cache::failure_cache fcache = get_failure_cache();
if (has_expr_metavar(t) || has_expr_metavar(s)) return false;
type_context_cache::failure_cache const & fcache = get_failure_cache();
if (t.hash() < s.hash()) {
return fcache.find(mk_pair(t, s)) != fcache.end();
} else if (t.hash() > s.hash()) {
@ -2319,7 +2320,8 @@ lbool type_context::is_def_eq_lazy_delta(expr & t, expr & s) {
if (is_eqp(*d_t, *d_s)) {
/* Same constant */
if (is_app(t) && is_app(s)) {
{
bool has_postponed = !m_postponed.empty();
if (!is_cached_failure(t, s)) {
/* Heuristic: try so solve (f a =?= f b), by solving (a =?= b) */
scope S(*this);
if (is_def_eq_args(t, s) &&
@ -2327,6 +2329,8 @@ lbool type_context::is_def_eq_lazy_delta(expr & t, expr & s) {
process_postponed(S)) {
S.commit();
return l_true;
} else if (!has_postponed && !has_expr_metavar(t) && !has_expr_metavar(s)) {
cache_failure(t, s);
}
}
/* Heuristic failed, then unfold both of them */
@ -2652,15 +2656,13 @@ bool type_context::is_def_eq_core_core(expr const & t, expr const & s) {
if (is_local(t_n) && is_local(s_n) && mlocal_name(t_n) == mlocal_name(s_n))
return true;
if (is_app(t_n) && is_app(s_n) && !is_cached_failure(t_n, s_n)) {
if (is_app(t_n) && is_app(s_n)) {
scope s(*this);
if (is_def_eq_core(get_app_fn(t_n), get_app_fn(s_n)) &&
is_def_eq_args(t_n, s_n) &&
process_postponed(s)) {
s.commit();
return true;
} else if (!has_expr_metavar(t_n) && !has_expr_metavar(s_n)) {
cache_failure(t_n, s_n);
}
}

13
tests/lean/run/exact_perf.lean Normal file
View file

@ -0,0 +1,13 @@
open nat
def f (a : nat) : nat := a
def g (a : nat) : nat := a
constant p : nat → Prop
example (a b : nat) (h1 : false) (h2 : p (g (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f a))))))))))))))))))))))))))))))) :
p (g (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f (f b)))))))))))))))))))))))))))))))
:=
begin
try {exact h2},
contradiction
end