erl_bifs: Remove pure BIFs serving no useful purpose

Functions that can are known be pure can be evaluated at
compile-time if the arguments are literals and if the result is
expressible as a literal.

list_to_ref/1 and list_to_port/1 returns terms that cannot be
expressed as literals, so the optimization is not possible.
The argument for port_to_list/1 is never a literal, so there is
no way to evaluate it at compile-time. Therefore, marking those
functions as pure serves no useful purpose.

Note: list_to_pid/1 *is* marked as pure, but only so that we can test
the code in sys_core_fold that rejects pure functions that evaluate to
at term that is not possible to express as a literal. It is sufficient
to have one pure function of that kind.

1 files changed, 0 insertions, 3 deletions

diff --git a/lib/compiler/src/erl_bifs.erl b/lib/compiler/src/erl_bifs.erl
index 043fe227a9..bafa9d75b7 100644
--- a/lib/compiler/src/erl_bifs.erl
+++ b/lib/compiler/src/erl_bifs.erl
@@ -107,14 +107,11 @@ is_pure(erlang, list_to_binary, 1) -> true;
 is_pure(erlang, list_to_float, 1) -> true;
 is_pure(erlang, list_to_integer, 1) -> true;
 is_pure(erlang, list_to_pid, 1) -> true;
-is_pure(erlang, list_to_port, 1) -> true;
-is_pure(erlang, list_to_ref, 1) -> true;
 is_pure(erlang, list_to_tuple, 1) -> true;
 is_pure(erlang, max, 2) -> true;
 is_pure(erlang, min, 2) -> true;
 is_pure(erlang, phash, 2) -> false;
 is_pure(erlang, pid_to_list, 1) -> true;
-is_pure(erlang, port_to_list, 1) -> true;
 is_pure(erlang, round, 1) -> true;
 is_pure(erlang, setelement, 3) -> true;
 is_pure(erlang, size, 1) -> true;