ZJIT: Upgrade self to HeapBasicObject in normal methods on most classes (#17155)HEADmaster

If the ISEQ we're compiling is a `ISEQ_TYPE_METHOD` and it's defined on a
class that no immediate object's class inherits from (exclude
`BasicObject`, `Object`, `Numeric`, etc), and the allocator is the
default allocator, then we can assume the `self` is heap-allocated.

This lets us skip HeapBasicObject guards for a lot of instance variable
lookups, for example:

```ruby
class C
  def foo = @foo
end
```

Thanks to @jhawthorn for the idea and @tenderlove for convincing me it was reasonable.

0 files changed, 0 insertions, 0 deletions