Get rid of frozen shapes.

Instead `shape_id_t` higher bits contain flags, and the first one
tells whether the shape is frozen.

This has multiple benefits:
  - Can check if a shape is frozen with a single bit check instead of
    dereferencing a pointer.
  - Guarantees it is always possible to transition to frozen.
  - This allow reclaiming `FL_FREEZE` (not done yet).

The downside is you have to be careful to preserve these flags
when transitioning.

1 files changed, 2 insertions, 14 deletions

diff --git a/object.c b/object.c
index 9bd1d96e9f..e6ad182651 100644
--- a/object.c
+++ b/object.c
@@ -496,12 +496,7 @@ rb_obj_clone_setup(VALUE obj, VALUE clone, VALUE kwfreeze)
 
         if (RB_OBJ_FROZEN(obj)) {
             shape_id_t next_shape_id = rb_shape_transition_frozen(clone);
-            if (!rb_shape_obj_too_complex_p(clone) && rb_shape_too_complex_p(next_shape_id)) {
-                rb_evict_ivars_to_hash(clone);
-            }
-            else {
-                rb_obj_set_shape_id(clone, next_shape_id);
-            }
+            rb_obj_set_shape_id(clone, next_shape_id);
         }
         break;
       case Qtrue: {
@@ -518,14 +513,7 @@ rb_obj_clone_setup(VALUE obj, VALUE clone, VALUE kwfreeze)
         rb_funcallv_kw(clone, id_init_clone, 2, argv, RB_PASS_KEYWORDS);
         RBASIC(clone)->flags |= FL_FREEZE;
         shape_id_t next_shape_id = rb_shape_transition_frozen(clone);
-        // If we're out of shapes, but we want to freeze, then we need to
-        // evacuate this clone to a hash
-        if (!rb_shape_obj_too_complex_p(clone) && rb_shape_too_complex_p(next_shape_id)) {
-            rb_evict_ivars_to_hash(clone);
-        }
-        else {
-            rb_obj_set_shape_id(clone, next_shape_id);
-        }
+        rb_obj_set_shape_id(clone, next_shape_id);
         break;
       }
       case Qfalse: {