RHash isn't a good fit for storing `cdhash` as this force to allow
arbitrary hash types into RHash, which doesn't work with AR tables.
It also cause the cdhash to be larger than needed.
[Bug #21952]
Solves the double-free or use after-free concern with boxes.
Now entries can safely be used for copy-on-write.
Also is likely necessary to make it save to read cvar from
secondary ractors, as allowed since: ab32c0e690b805cdaaf264ad4c3421696c588204
This behave almost exactly as a T_OBJECT, the layout is entirely
compatible.
This aims to solve two problems.
First, it solves the problem of namspaced classes having
a single `shape_id`. Now each namespaced classext
has an object that can hold the namespace specific
shape.
Second, it open the door to later make class instance variable
writes atomics, hence be able to read class variables
without locking the VM.
In the future, in multi-ractor mode, we can do the write
on a copy of the `fields_obj` and then atomically swap it.
Considerations:
- Right now the `RClass` shape_id is always synchronized,
but with namespace we should likely mark classes that have
multiple namespace with a specific shape flag.
This commit splits gc.c into two files:
- gc.c now only contains code not specific to Ruby GC. This includes
code to mark objects (which the GC implementation may choose not to
use) and wrappers for internal APIs that the implementation may need
to use (e.g. locking the VM).
- gc_impl.c now contains the implementation of Ruby's GC. This includes
marking, sweeping, compaction, and statistics. Most importantly,
gc_impl.c only uses public APIs in Ruby and a limited set of functions
exposed in gc.c. This allows us to build gc_impl.c independently of
Ruby and plug Ruby's GC into itself.
Node has not been managed by GC from Ruby 2.5.
Therefore these codes are not needed. If ObjectSpace depends on Node,
it needs to update the file when node type is updated. Delete node
related codes to avoid such update.
All kind of AST nodes use same struct RNode, which has u1, u2, u3 union members
for holding different kind of data.
This has two problems.
1. Low flexibility of data structure
Some nodes, for example NODE_TRUE, don’t use u1, u2, u3. On the other hand,
NODE_OP_ASGN2 needs more than three union members. However they use same
structure definition, need to allocate three union members for NODE_TRUE and
need to separate NODE_OP_ASGN2 into another node.
This change removes the restriction so make it possible to
change data structure by each node type.
2. No compile time check for union member access
It’s developer’s responsibility for using correct member for each node type when it’s union.
This change clarifies which node has which type of fields and enables compile time check.
This commit also changes node_buffer_elem_struct buf management to handle
different size data with alignment.
By this change, syntax error is recovered smaller units.
In the case below, "DEFN :bar" is same level with "CLASS :Foo"
now.
```
module Z
class Foo
foo.
end
def bar
end
end
```
[Feature #19013]
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>
Inside ObjectSpace.reachable_objects_from we keep an internal identhash
in order to de-duplicate reachable objects when wrapping them as
InternalObject. Previously this hash was not hidden, making it possible
to leak references to those internal objects to Ruby if using
ObjectSpace.each_object.
This commit solves this by hiding the hash. To simplify collection of
values, we instead now just use the hash as a set of visited objects,
and collect an Array (not hidden) of values to be returned.
This `NODE` type was used in pre-YARV implementation, to improve
the performance of assignment to dynamic local variable defined at
the innermost scope. It has no longer any actual difference with
`NODE_DASGN`, except for the node dump.
This commit removes T_PAYLOAD since the new VWA implementation no longer
requires T_PAYLOAD types.
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
This reverts commits 48ff7a9f3e47bffb3e4d067a12ba9b936261caa0
and b2e2cf2dedd104acad8610721db5e4d341f135ef because it is causing
crashes in SPARC solaris and i386 debian.
This commit removes T_PAYLOAD since the new VWA implementation no longer
requires T_PAYLOAD types.
Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org>
