Commit graph

61 commits

Author SHA1 Message Date
Jemma Issroff
7ee1cacb84 Extract rb_shape_get_parent helper
Extract an `rb_shape_get_parent` method instead of continually calling
`rb_shape_get_shape_by_id(shape->parent_id)`
2022-11-10 13:02:50 -05:00
Jemma Issroff
5246f4027e Transition shape when object's capacity changes
This commit adds a `capacity` field to shapes, and adds shape
transitions whenever an object's capacity changes. Objects which are
allocated out of a bigger size pool will also make a transition from the
root shape to the shape with the correct capacity for their size pool
when they are allocated.

This commit will allow us to remove numiv from objects completely, and
will also mean we can guarantee that if two objects share shapes, their
IVs are in the same positions (an embedded and extended object cannot
share shapes). This will enable us to implement ivar sets in YJIT using
object shapes.

Co-Authored-By: Aaron Patterson <tenderlove@ruby-lang.org>
2022-11-10 10:11:34 -05:00
John Hawthorn
02f1554224
Implement object shapes for T_CLASS and T_MODULE (#6637)
* Avoid RCLASS_IV_TBL in marshal.c
* Avoid RCLASS_IV_TBL for class names
* Avoid RCLASS_IV_TBL for autoload
* Avoid RCLASS_IV_TBL for class variables
* Avoid copying RCLASS_IV_TBL onto ICLASSes
* Use object shapes for Class and Module IVs
2022-10-31 14:05:37 -07:00
Jemma Issroff
a11952dac1 Rename iv_count on shapes to next_iv_index
`iv_count` is a misleading name because when IVs are unset, the new
shape doesn't decrement this value. `next_iv_count` is an accurate, and
more descriptive name.
2022-10-21 14:57:34 -07:00
Aaron Patterson
f0654b1027 More precisely iterate over Object instance variables
Shapes provides us with an (almost) exact count of instance variables.
We only need to check for Qundef when an IV has been "undefined"
Prefer to use ROBJECT_IV_COUNT when iterating IVs
2022-10-15 10:44:10 -07:00
Jemma Issroff
913979bede
Make inline cache reads / writes atomic with object shapes
Prior to this commit, we were reading and writing ivar index and
shape ID in inline caches in two separate instructions when
getting and setting ivars. This meant there was a race condition
with ractors and these caches where one ractor could change
a value in the cache while another was still reading from it.

This commit instead reads and writes shape ID and ivar index to
inline caches atomically so there is no longer a race condition.

Co-Authored-By: Aaron Patterson <tenderlove@ruby-lang.org>
Co-Authored-By: John Hawthorn <john@hawthorn.email>
2022-10-11 08:40:56 -07:00
Jemma Issroff
ad63b668e2
Revert "Revert "This commit implements the Object Shapes technique in CRuby.""
This reverts commit 9a6803c90b.
2022-10-11 08:40:56 -07:00
Aaron Patterson
9a6803c90b
Revert "This commit implements the Object Shapes technique in CRuby."
This reverts commit 68bc9e2e97d12f80df0d113e284864e225f771c2.
2022-09-30 16:01:50 -07:00
Jemma Issroff
d594a5a8bd
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>
2022-09-28 08:26:21 -07:00
Aaron Patterson
06abfa5be6
Revert this until we can figure out WB issues or remove shapes from GC
Revert "* expand tabs. [ci skip]"

This reverts commit 830b5b5c35.

Revert "This commit implements the Object Shapes technique in CRuby."

This reverts commit 9ddfd2ca00.
2022-09-26 16:10:11 -07:00
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