Make classes embedded on 32 bit

Classes are now exactly 80 bytes when embedded, which perfectly fits the
3rd size pool on 32 bit systems.

class.c

@@ -193,22 +193,14 @@ rb_class_detach_module_subclasses(VALUE klass)
 static VALUE
 class_alloc(VALUE flags, VALUE klass)
 {
-    size_t alloc_size = sizeof(struct RClass);
-
-#if RCLASS_EXT_EMBEDDED
-    alloc_size += sizeof(rb_classext_t);
-#endif
+    size_t alloc_size = sizeof(struct RClass) + sizeof(rb_classext_t);
 
     flags &= T_MASK;
     flags |= FL_PROMOTED1 /* start from age == 2 */;
     if (RGENGC_WB_PROTECTED_CLASS) flags |= FL_WB_PROTECTED;
     NEWOBJ_OF(obj, struct RClass, klass, flags, alloc_size, 0);
 
-#if RCLASS_EXT_EMBEDDED
     memset(RCLASS_EXT(obj), 0, sizeof(rb_classext_t));
-#else
-    obj->ptr = ZALLOC(rb_classext_t);
-#endif
 
     /* ZALLOC
       RCLASS_CONST_TBL(obj) = 0;

gc.c

@@ -3513,11 +3513,6 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
             xfree(RCLASS_SUPERCLASSES(obj));
         }
 
-#if !RCLASS_EXT_EMBEDDED
-        if (RCLASS_EXT(obj))
-            xfree(RCLASS_EXT(obj));
-#endif
-
         (void)RB_DEBUG_COUNTER_INC_IF(obj_module_ptr, BUILTIN_TYPE(obj) == T_MODULE);
         (void)RB_DEBUG_COUNTER_INC_IF(obj_class_ptr, BUILTIN_TYPE(obj) == T_CLASS);
         break;
@@ -3644,9 +3639,6 @@ obj_free(rb_objspace_t *objspace, VALUE obj)
         cc_table_free(objspace, obj, FALSE);
         rb_class_remove_from_module_subclasses(obj);
         rb_class_remove_from_super_subclasses(obj);
-#if !RCLASS_EXT_EMBEDDED
-        xfree(RCLASS_EXT(obj));
-#endif
 
         RB_DEBUG_COUNTER_INC(obj_iclass_ptr);
         break;
@@ -4905,9 +4897,6 @@ obj_memsize_of(VALUE obj, int use_all_types)
             if (FL_TEST_RAW(obj, RCLASS_SUPERCLASSES_INCLUDE_SELF)) {
                 size += (RCLASS_SUPERCLASS_DEPTH(obj) + 1) * sizeof(VALUE);
             }
-#if !RCLASS_EXT_EMBEDDED
-            size += sizeof(rb_classext_t);
-#endif
         }
         break;
       case T_ICLASS:

internal/class.h

@@ -76,21 +76,12 @@ struct RClass {
     struct RBasic basic;
     VALUE super;
     struct rb_id_table *m_tbl;
-#if !RCLASS_EXT_EMBEDDED
-    struct rb_classext_struct *ptr;
-#endif
 };
 
-#if RCLASS_EXT_EMBEDDED
 // Assert that classes can be embedded in size_pools[2] (which has 160B slot size)
 STATIC_ASSERT(sizeof_rb_classext_t, sizeof(struct RClass) + sizeof(rb_classext_t) <= 4 * RVALUE_SIZE);
-#endif
 
-#if RCLASS_EXT_EMBEDDED
-#  define RCLASS_EXT(c) ((rb_classext_t *)((char *)(c) + sizeof(struct RClass)))
-#else
-#  define RCLASS_EXT(c) (RCLASS(c)->ptr)
-#endif
+#define RCLASS_EXT(c) ((rb_classext_t *)((char *)(c) + sizeof(struct RClass)))
 #define RCLASS_CONST_TBL(c) (RCLASS_EXT(c)->const_tbl)
 #define RCLASS_M_TBL(c) (RCLASS(c)->m_tbl)
 #define RCLASS_IVPTR(c) (RCLASS_EXT(c)->iv_ptr)

internal/gc.h

@@ -189,9 +189,6 @@ struct rb_objspace; /* in vm_core.h */
 # define SIZE_POOL_COUNT 5
 #endif
 
-// TODO: Make rb_classext_t small enough to fit in 80 bytes on 32 bit
-#define RCLASS_EXT_EMBEDDED (SIZEOF_UINT64_T == SIZEOF_VALUE)
-
 typedef struct ractor_newobj_size_pool_cache {
     struct RVALUE *freelist;
     struct heap_page *using_page;