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>
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>
except for bit fields.
I made a risky assumption on leading bit fields and just gave up
non-leading bit fields for now. I'll change it to let C code access bit
fields later.
The reason why this was commented out was because of gperf 3.0 vs 3.1
differences (see [Feature #13883]). Five years passed, I am pretty
confident that we can drop support of old versions here.
Ditto for uniname2ctype_p(), onig_jis_property(), and zonetab().
when -q is given.
One of the RubyCI servers, freebsd12, had a broken git environment:
```
$ git show
fatal: detected dubious ownership in repository at '/usr/home/chkbuild/chkbuild/tmp/build/20220917T123002Z/ruby'
To add an exception for this directory, call:
git config --global --add safe.directory /usr/home/chkbuild/chkbuild/tmp/build/20220917T123002Z/ruby
```
tool/lib/vcs.rb doesn't work normally for that server.
Even for such cases, we'd like to generate a usable revision.h.
So this patch lets revision.h fallback to default VCS.release_date
when VCS::NotFoundError is raised.
* So deprecated methods/constants/functions are dealt with early,
instead of many tests breaking suddenly when removing a deprecated
method/constant/function.
* Follows https://bugs.ruby-lang.org/issues/17591
I want to use more complicated macros with MJIT. For example:
```
# define SHAPE_MASK (((unsigned int)1 << SHAPE_BITS) - 1)
```
This commit adds a simple recursive descent parser that produces an AST
and a small visitor that converts the AST to Ruby.
Aaron Patterson
Nobuyoshi Nakada
Jemma Issroff
Takashi Kokubun
卜部昌平
Hiroshi SHIBATA
Benoit Daloze