Implement magic references

Magic references are *intentionally* indistinguishable from ordinary
references for the Erlang software. Magic references do not change
the language, and are intended as a pure runtime internal optimization.

An ordinary reference is typically used as a key in some table. A
magic reference has a direct pointer to a reference counted magic
binary. This makes it possible to implement various things without
having to do lookups in a table, but instead access the data directly.
Besides very fast lookups this can also improve scalability by
removing a potentially contended table. A couple of examples of
planned future usage of magic references are ETS table identifiers,
and BIF timer identifiers.

Besides future optimizations using magic references it should also
be possible to replace the exposed magic binary cludge with magic
references. That is, magic binaries that are exposed as empty
binaries to the Erlang software.

1 files changed, 4 insertions, 0 deletions

diff --git a/erts/emulator/beam/erl_alloc.types b/erts/emulator/beam/erl_alloc.types
index 70eca5b49c..c253ea82c8 100644
--- a/erts/emulator/beam/erl_alloc.types
+++ b/erts/emulator/beam/erl_alloc.types
@@ -280,6 +280,10 @@ type    TRACE_MSG_QUEUE SHORT_LIVED     SYSTEM          trace_message_queue
 type    SCHED_ASYNC_JOB SHORT_LIVED     SYSTEM          async_calls
 type    DIRTY_START     STANDARD	PROCESSES       dirty_start
 type    DIRTY_SL	SHORT_LIVED	SYSTEM		dirty_short_lived
+type    MREF_NSCHED_ENT	FIXED_SIZE	SYSTEM		nsched_magic_ref_entry
+type    MREF_ENT	STANDARD	SYSTEM		magic_ref_entry
+type	MREF_TAB_BKTS	STANDARD	SYSTEM		magic_ref_table_buckets
+type	MREF_TAB	LONG_LIVED	SYSTEM		magic_ref_table
 
 +if threads_no_smp
 # Need thread safe allocs, but std_alloc and fix_alloc are not;