refactor(kernel/default_converter): separate lazy_delta_reduction procedure
This commit is contained in:
Leonardo de Moura
parent
1c70514231
commit
a518a45239
2 changed files with 78 additions and 46 deletions
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@ -466,6 +466,77 @@ void default_converter::cache_failure(expr const & t, expr const & s) {
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m_failure_cache.insert(mk_pair(s, t));
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m_failure_cache.insert(mk_pair(s, t));
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}
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}
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/**
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\brief Perform one lazy delta-reduction step.
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Return
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- l_true if t_n and s_n are definitionally equal.
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- l_false if they are not definitionally equal.
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- l_undef it the step did not manage to establish whether they are definitionally equal or not.
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\remark t_n, s_n and cs are updated.
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*/
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auto default_converter::lazy_delta_reduction_step(expr & t_n, expr & s_n, constraint_seq & cs) -> lazy_delta_result {
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auto d_t = is_delta(t_n);
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auto d_s = is_delta(s_n);
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if (!d_t && !d_s) {
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return lazy_delta_result::DefUnknown;
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} else if (d_t && !d_s) {
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t_n = whnf_core(unfold_names(t_n, 0));
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} else if (!d_t && d_s) {
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s_n = whnf_core(unfold_names(s_n, 0));
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} else if (d_t->get_weight() > d_s->get_weight()) {
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t_n = whnf_core(unfold_names(t_n, d_s->get_weight() + 1));
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} else if (d_t->get_weight() < d_s->get_weight()) {
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s_n = whnf_core(unfold_names(s_n, d_t->get_weight() + 1));
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} else {
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lean_assert(d_t && d_s && d_t->get_weight() == d_s->get_weight());
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if (is_app(t_n) && is_app(s_n) && is_eqp(*d_t, *d_s)) {
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// If t_n and s_n are both applications of the same (non-opaque) definition,
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if (has_expr_metavar(t_n) || has_expr_metavar(s_n)) {
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// We let the unifier deal with cases such as
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// (f ...) =?= (f ...)
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// when t_n or s_n contains metavariables
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return lazy_delta_result::DefUnknown;
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} else {
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// Optimization:
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// We try to check if their arguments are definitionally equal.
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// If they are, then t_n and s_n must be definitionally equal, and we can
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// skip the delta-reduction step.
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// If the flag use_conv_opt() is not true, then we skip this optimization
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constraint_seq tmp_cs;
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if (!is_opaque(*d_t) && d_t->use_conv_opt() && !failed_before(t_n, s_n)) {
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if (is_def_eq(const_levels(get_app_fn(t_n)), const_levels(get_app_fn(s_n)), tmp_cs) &&
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is_def_eq_args(t_n, s_n, tmp_cs)) {
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cs += tmp_cs;
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return lazy_delta_result::DefEqual;
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} else {
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cache_failure(t_n, s_n);
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}
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}
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}
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}
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t_n = whnf_core(unfold_names(t_n, d_t->get_weight() - 1));
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s_n = whnf_core(unfold_names(s_n, d_s->get_weight() - 1));
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}
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switch (quick_is_def_eq(t_n, s_n, cs)) {
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case l_true: return lazy_delta_result::DefEqual;
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case l_false: return lazy_delta_result::DefDiff;
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case l_undef: return lazy_delta_result::Continue;
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}
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lean_unreachable();
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}
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lbool default_converter::lazy_delta_reduction(expr & t_n, expr & s_n, constraint_seq & cs) {
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while (true) {
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switch (lazy_delta_reduction_step(t_n, s_n, cs)) {
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case lazy_delta_result::Continue: break;
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case lazy_delta_result::DefUnknown: return l_undef;
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case lazy_delta_result::DefEqual: return l_true;
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case lazy_delta_result::DefDiff: return l_false;
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}
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}
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}
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pair<bool, constraint_seq> default_converter::is_def_eq_core(expr const & t, expr const & s) {
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pair<bool, constraint_seq> default_converter::is_def_eq_core(expr const & t, expr const & s) {
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check_system("is_definitionally_equal");
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check_system("is_definitionally_equal");
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constraint_seq cs;
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constraint_seq cs;
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@ -485,52 +556,9 @@ pair<bool, constraint_seq> default_converter::is_def_eq_core(expr const & t, exp
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// lazy delta-reduction and then normalizer extensions
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// lazy delta-reduction and then normalizer extensions
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while (true) {
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while (true) {
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// first, keep applying lazy delta-reduction while applicable
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// first, keep applying lazy delta-reduction while applicable
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while (true) {
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r = lazy_delta_reduction(t_n, s_n, cs);
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auto d_t = is_delta(t_n);
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if (r != l_undef) return to_bcs(r == l_true, cs);
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auto d_s = is_delta(s_n);
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if (!d_t && !d_s) {
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break;
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} else if (d_t && !d_s) {
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t_n = whnf_core(unfold_names(t_n, 0));
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} else if (!d_t && d_s) {
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s_n = whnf_core(unfold_names(s_n, 0));
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} else if (d_t->get_weight() > d_s->get_weight()) {
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t_n = whnf_core(unfold_names(t_n, d_s->get_weight() + 1));
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} else if (d_t->get_weight() < d_s->get_weight()) {
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s_n = whnf_core(unfold_names(s_n, d_t->get_weight() + 1));
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} else {
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lean_assert(d_t && d_s && d_t->get_weight() == d_s->get_weight());
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if (is_app(t_n) && is_app(s_n) && is_eqp(*d_t, *d_s)) {
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// If t_n and s_n are both applications of the same (non-opaque) definition,
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if (has_expr_metavar(t_n) || has_expr_metavar(s_n)) {
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// We let the unifier deal with cases such as
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// (f ...) =?= (f ...)
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// when t_n or s_n contains metavariables
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break;
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} else {
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// Optimization:
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// We try to check if their arguments are definitionally equal.
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// If they are, then t_n and s_n must be definitionally equal, and we can
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// skip the delta-reduction step.
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// If the flag use_conv_opt() is not true, then we skip this optimization
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constraint_seq tmp_cs;
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if (!is_opaque(*d_t) && d_t->use_conv_opt() && !failed_before(t_n, s_n)) {
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if (is_def_eq(const_levels(get_app_fn(t_n)), const_levels(get_app_fn(s_n)), tmp_cs) &&
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is_def_eq_args(t_n, s_n, tmp_cs)) {
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cs += tmp_cs;
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return to_bcs(true, cs);
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} else {
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cache_failure(t_n, s_n);
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}
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}
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}
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}
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t_n = whnf_core(unfold_names(t_n, d_t->get_weight() - 1));
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s_n = whnf_core(unfold_names(s_n, d_s->get_weight() - 1));
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}
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r = quick_is_def_eq(t_n, s_n, cs);
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if (r != l_undef) return to_bcs(r == l_true, cs);
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}
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// try normalizer extensions
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// try normalizer extensions
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auto new_t_n = d_norm_ext(t_n, cs);
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auto new_t_n = d_norm_ext(t_n, cs);
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auto new_s_n = d_norm_ext(s_n, cs);
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auto new_s_n = d_norm_ext(s_n, cs);
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@ -78,6 +78,10 @@ protected:
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pair<bool, constraint_seq> is_def_eq_core(expr const & t, expr const & s);
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pair<bool, constraint_seq> is_def_eq_core(expr const & t, expr const & s);
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pair<bool, constraint_seq> is_def_eq(expr const & t, expr const & s);
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pair<bool, constraint_seq> is_def_eq(expr const & t, expr const & s);
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enum class lazy_delta_result { Continue, DefUnknown, DefEqual, DefDiff };
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lazy_delta_result lazy_delta_reduction_step(expr & t_n, expr & s_n, constraint_seq & cs);
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lbool lazy_delta_reduction(expr & t_n, expr & s_n, constraint_seq & cs);
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public:
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public:
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default_converter(environment const & env, bool memoize = true);
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default_converter(environment const & env, bool memoize = true);
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