The `p->field = rb_gc_location(p->field)` isn't ideal because it means all
references are rewritten on compaction, regardless of whether the referenced
object has moved. This isn't good for caches nor for Copy-on-Write.
`rb_gc_mark_and_move` avoid needless writes, and most of the time allow to
have a single function for both marking and updating references.
Once klass becomes Qundef, it's disconnected and won't be invalidated
when the CME is. So once that happens we must not mark or attempt to
move the cme_ field.
* ZJIT: Implement SingleRactorMode invalidation
* ZJIT: Add macro for compiling jumps
* ZJIT: Fix typo in comment
* YJIT: Fix typo in comment
* ZJIT: Avoid using unexported types in zjit.h
`enum ruby_vminsn_type` is declared in `insns.inc` and is not exported.
Using it in `zjit.h` would cause build errors when the file including it
doesn't include `insns.inc`.
Previously we crashed panicked due to index bounds check running
test_fixnum.rb.
On ARM and in other places in the x86 backend, this isn't a problem
because they inspect the output of instructions which is never replaced.
Symbol last_id was changed to next_id, but it remained to be set to
tNEXT_ID - 1 initially, causing the initial static symbol to overlap with
the last built-in symbol in id.def.
It's not rare for structs to have additional ivars, hence are one
of the most common, if not the most common type in the `gen_fields_tbl`.
This can cause Ractor contention, but even in single ractor mode
means having to do a hash lookup to access the ivars, and increase
GC work.
Instead, unless the struct is perfectly right sized, we can store
a reference to the associated IMEMO/fields object right after the
last struct member.
```
compare-ruby: ruby 3.5.0dev (2025-08-06T12:50:36Z struct-ivar-fields-2 9a30d141a1) +PRISM [arm64-darwin24]
built-ruby: ruby 3.5.0dev (2025-08-06T12:57:59Z struct-ivar-fields-2 2ff3ec237f) +PRISM [arm64-darwin24]
warming up.....
| |compare-ruby|built-ruby|
|:---------------------|-----------:|---------:|
|member_reader | 590.317k| 579.246k|
| | 1.02x| -|
|member_writer | 543.963k| 527.104k|
| | 1.03x| -|
|member_reader_method | 213.540k| 213.004k|
| | 1.00x| -|
|member_writer_method | 192.657k| 191.491k|
| | 1.01x| -|
|ivar_reader | 403.993k| 569.915k|
| | -| 1.41x|
```
Co-Authored-By: Étienne Barrié <etienne.barrie@gmail.com>
ZJIT uses the interpreter to take type profiles of what objects pass through
the code. It stores a compressed record of the history per opcode for the
opcodes we select.
Before this change, we re-used the HIR Type data-structure, a shallow type
lattice, to store historical type information. This was quick for bringup but
is quite lossy as profiles go: we get one bit per built-in type seen, and if we
see a non-built-in type in addition, we end up with BasicObject. Not very
helpful. Additionally, it does not give us any notion of cardinality: how many
of each type did we see?
This change brings with it a much more interesting slice of type history: a
histogram. A Distribution holds a record of the top-N (where N is fixed at Ruby
compile-time) `(Class, ShapeId)` pairs and their counts. It also holds an
*other* count in case we see more than N pairs.
Using this distribution, we can make more informed decisions about when we
should use type information. We can determine if we are strictly monomorphic,
very nearly monomorphic, or something else. Maybe the call-site is polymorphic,
so we should have a polymorphic inline cache. Exciting stuff.
I also plumb this new distribution into the HIR part of the compilation
pipeline.
Currently Prism returns `42` for code like this:
```ruby
42.tap { it = it; p it } # => 42
```
But parse.y returns `nil`:
```ruby
42.tap { it = it; p it } # => nil
```
In parse.y, it on the right-hand side is parsed as a local variable.
In Prism, it was parsed as the implicit block parameter it, which caused this inconsistent behavior.
This change makes the right-hand side it to be parsed as a local variable, aligning with parse.y's behavior.
Bug ticket: https://bugs.ruby-lang.org/issues/21139cf3bbf9d2c
Assuming not all objects are moved during compaction, it
is preferable to avoid rewriting references that haven't moved
as to avoid invalidating potentially shared memory pages.
When compiling with -fsanitize=address on macOS, the deprecation of
sprintf is effective and prevents compiling yjit.c.
More details: https://openradar.appspot.com/FB11761475.
