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authorJemma Issroff <jemmaissroff@gmail.com>2022-09-23 13:54:42 -0400
committerAaron Patterson <aaron.patterson@gmail.com>2022-09-26 09:21:30 -0700
commit9ddfd2ca004d1952be79cf1b84c52c79a55978f4 (patch)
treefe5fa943d9a2dc7438db920a09173ab06f869993 /internal/class.h
parent2e88bca24ff4cafeb6afe5b062ff7181bc4b3a9b (diff)
This commit implements the Object Shapes technique in CRuby.
Object Shapes is used for accessing instance variables and representing the "frozenness" of objects. Object instances have a "shape" and the shape represents some attributes of the object (currently which instance variables are set and the "frozenness"). Shapes form a tree data structure, and when a new instance variable is set on an object, that object "transitions" to a new shape in the shape tree. Each shape has an ID that is used for caching. The shape structure is independent of class, so objects of different types can have the same shape. For example: ```ruby class Foo def initialize # Starts with shape id 0 @a = 1 # transitions to shape id 1 @b = 1 # transitions to shape id 2 end end class Bar def initialize # Starts with shape id 0 @a = 1 # transitions to shape id 1 @b = 1 # transitions to shape id 2 end end foo = Foo.new # `foo` has shape id 2 bar = Bar.new # `bar` has shape id 2 ``` Both `foo` and `bar` instances have the same shape because they both set instance variables of the same name in the same order. This technique can help to improve inline cache hits as well as generate more efficient machine code in JIT compilers. This commit also adds some methods for debugging shapes on objects. See `RubyVM::Shape` for more details. For more context on Object Shapes, see [Feature: #18776] Co-Authored-By: Aaron Patterson <tenderlove@ruby-lang.org> Co-Authored-By: Eileen M. Uchitelle <eileencodes@gmail.com> Co-Authored-By: John Hawthorn <john@hawthorn.email>
Notes
Notes: Merged: https://github.com/ruby/ruby/pull/6386
Diffstat (limited to 'internal/class.h')
-rw-r--r--internal/class.h11
1 files changed, 6 insertions, 5 deletions
diff --git a/internal/class.h b/internal/class.h
index ae680564a6..36635d6eaa 100644
--- a/internal/class.h
+++ b/internal/class.h
@@ -14,6 +14,7 @@
#include "ruby/internal/stdbool.h" /* for bool */
#include "ruby/intern.h" /* for rb_alloc_func_t */
#include "ruby/ruby.h" /* for struct RBasic */
+#include "shape.h"
#ifdef RCLASS_SUPER
# undef RCLASS_SUPER
@@ -26,9 +27,9 @@ struct rb_subclass_entry {
};
struct rb_iv_index_tbl_entry {
- uint32_t index;
- rb_serial_t class_serial;
- VALUE class_value;
+ uint32_t idx;
+ shape_id_t source_shape_id;
+ shape_id_t dest_shape_id;
};
struct rb_cvar_class_tbl_entry {
@@ -38,7 +39,6 @@ struct rb_cvar_class_tbl_entry {
};
struct rb_classext_struct {
- struct st_table *iv_index_tbl; // ID -> struct rb_iv_index_tbl_entry
struct st_table *iv_tbl;
#if SIZEOF_SERIAL_T == SIZEOF_VALUE /* otherwise m_tbl is in struct RClass */
struct rb_id_table *m_tbl;
@@ -64,6 +64,8 @@ struct rb_classext_struct {
const VALUE refined_class;
rb_alloc_func_t allocator;
const VALUE includer;
+ uint32_t max_iv_count;
+ uint16_t shape_id;
};
struct RClass {
@@ -102,7 +104,6 @@ typedef struct rb_classext_struct rb_classext_t;
#define RCLASS_CALLABLE_M_TBL(c) (RCLASS_EXT(c)->callable_m_tbl)
#define RCLASS_CC_TBL(c) (RCLASS_EXT(c)->cc_tbl)
#define RCLASS_CVC_TBL(c) (RCLASS_EXT(c)->cvc_tbl)
-#define RCLASS_IV_INDEX_TBL(c) (RCLASS_EXT(c)->iv_index_tbl)
#define RCLASS_ORIGIN(c) (RCLASS_EXT(c)->origin_)
#define RCLASS_REFINED_CLASS(c) (RCLASS_EXT(c)->refined_class)
#if SIZEOF_SERIAL_T == SIZEOF_VALUE