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ruby--ruby/internal/variable.h
Jemma Issroff 9ddfd2ca00 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>
2022-09-26 09:21:30 -07:00

88 lines
2.8 KiB
C

#ifndef INTERNAL_VARIABLE_H /*-*-C-*-vi:se ft=c:*/
#define INTERNAL_VARIABLE_H
/**
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
* @brief Internal header for variables.
*/
#include "ruby/internal/config.h"
#include <stddef.h> /* for size_t */
#include "constant.h" /* for rb_const_entry_t */
#include "ruby/internal/stdbool.h" /* for bool */
#include "ruby/ruby.h" /* for VALUE */
/* global variable */
#define ROBJECT_TRANSIENT_FLAG FL_USER2
/* variable.c */
void rb_gc_mark_global_tbl(void);
void rb_gc_update_global_tbl(void);
size_t rb_generic_ivar_memsize(VALUE);
VALUE rb_search_class_path(VALUE);
VALUE rb_attr_delete(VALUE, ID);
VALUE rb_ivar_lookup(VALUE obj, ID id, VALUE undef);
void rb_autoload_str(VALUE mod, ID id, VALUE file);
VALUE rb_autoload_at_p(VALUE, ID, int);
NORETURN(VALUE rb_mod_const_missing(VALUE,VALUE));
rb_gvar_getter_t *rb_gvar_getter_function_of(ID);
rb_gvar_setter_t *rb_gvar_setter_function_of(ID);
void rb_gvar_readonly_setter(VALUE v, ID id, VALUE *_);
void rb_gvar_ractor_local(const char *name);
static inline bool ROBJ_TRANSIENT_P(VALUE obj);
static inline void ROBJ_TRANSIENT_SET(VALUE obj);
static inline void ROBJ_TRANSIENT_UNSET(VALUE obj);
uint32_t rb_obj_ensure_iv_index_mapping(VALUE obj, ID id);
struct gen_ivtbl;
int rb_gen_ivtbl_get(VALUE obj, ID id, struct gen_ivtbl **ivtbl);
RUBY_SYMBOL_EXPORT_BEGIN
/* variable.c (export) */
void rb_mark_generic_ivar(VALUE);
void rb_mv_generic_ivar(VALUE src, VALUE dst);
VALUE rb_const_missing(VALUE klass, VALUE name);
int rb_class_ivar_set(VALUE klass, ID vid, VALUE value);
void rb_iv_tbl_copy(VALUE dst, VALUE src);
RUBY_SYMBOL_EXPORT_END
MJIT_SYMBOL_EXPORT_BEGIN
VALUE rb_gvar_get(ID);
VALUE rb_gvar_set(ID, VALUE);
VALUE rb_gvar_defined(ID);
void rb_const_warn_if_deprecated(const rb_const_entry_t *, VALUE, ID);
void rb_init_iv_list(VALUE obj);
void rb_ensure_iv_list_size(VALUE obj, uint32_t len, uint32_t newsize);
struct gen_ivtbl * rb_ensure_generic_iv_list_size(VALUE obj, uint32_t newsize);
MJIT_SYMBOL_EXPORT_END
static inline bool
ROBJ_TRANSIENT_P(VALUE obj)
{
#if USE_TRANSIENT_HEAP
return FL_TEST_RAW(obj, ROBJECT_TRANSIENT_FLAG);
#else
return false;
#endif
}
static inline void
ROBJ_TRANSIENT_SET(VALUE obj)
{
#if USE_TRANSIENT_HEAP
FL_SET_RAW(obj, ROBJECT_TRANSIENT_FLAG);
#endif
}
static inline void
ROBJ_TRANSIENT_UNSET(VALUE obj)
{
#if USE_TRANSIENT_HEAP
FL_UNSET_RAW(obj, ROBJECT_TRANSIENT_FLAG);
#endif
}
#endif /* INTERNAL_VARIABLE_H */