The old size of `struct RBreak` was 56 bytes (`MRB_NO_BOXING`)
and it's bigger than other object structures. That increase the
size of `RVALUE` thus increase the total amount of memory consumption.
Now the method tables (in classes/modules and caches) keeps C function
pointers without wrapping in `struct RProc` objects. For the sake of
portability, `mrb_method_t` is represented by the struct and union, but
if the most significant bit of the pointer is not used by the platform,
`mrb_method_t` should be packed in `uintptr_t` to reduce memory usage.
`MRB_METHOD_TABLE_INLINE` is turned on by default for linux.
Instead of `irep` links, we added a `upper` link to `struct RProc`.
To make a space for the `upper` link, we moved `target_class` reference.
If a `Proc` does not have `env`, `target_class` is saved in an `union`
shared with `env` (if a `Proc` has env, you can tell it by `MRB_PROC_ENV_P()).
Otherwise `target_class` is referenced from `env->c`. We removed links
in `env` as well.
This change removes 2 members from `mrb_irep` struct, thus saving 2
words per method/proc/block. This also fixes potential memory leaks
due to the circular references caused by a link from `mrb_irep`.
Instead of `irep -> proc` chain, we use `irep -> irep` chain to
avoid GC bugs like #3804. We added `target_class` reference to
`mrb_irep` struct. That means one more word consumption per `irep`.
To enable method cache, define `MRB_METHOD_CACHE` or
`MRB_METHOD_CACHE_SIZE`. The cache size must be power of 2.
The default cache size is 128.
The measurement:
I measured simple benchmarks found in benchmark/ directory. With
method cache enabled, we gained 6-8% performance improvement, with
97-99% cache hit rate.
The change removes several internal instance variables used by
class name management. The variables `__classid__` and `__classpath__`
are no longer available. `__outer__` is used only for unnamed outer
classes/modules (and will be removed after they are named).
[Important note]
Along with this change we removed several public functions.
- mrb_class_outer_module()
- mrb_class_sym()
We believe no one have used those functions, but if you do, please
ask us for the workaround.
It reduces the memory consumption and sometimes improve the
performance as well. For example, the consumed memory size
of `bench/bm_ao_render.rb` is reduced from 1.2GB to 1GB, and
its total execution time become 18.795 sec from 22.229 sec.
Yukihiro "Matz" Matsumoto