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.
The outer class of the class/module definition should be taken from
`MRB_TARGET_CLASS(mrb->c->ci->proc)` not `mrb->c->ci->target_class`
which is the target of constant lookups.
Make `block_given?` to search for the top of the scope first.
The top of the scope means either:
* the top method body
* the enclosing class body
* the top-level
The special case is the method defined by `define_method` with a
block as in #3841. In cases like this, the method body (given by
a block) is not considered as the top of the scope. You need to use
`&block` in the block parameter if you want to know if a block is
given to the method.
This commit also changes the behavior of `MRB_PROC_SCOPE` flag.
Now it is only set if the `proc` is either a class body or a method
body defined in Ruby. It is no longer set for a block that given to
`define_method`.
When `block_given?` is called from a block given to `define_method`
as a method body, the `bidx` may not be within `env` saved closure.
In this case, it causes heap buffer overflow.
Unlike method definition, constant reference should start from
`MRB_PROC_TARGET_CLASS(ci->proc)`, not `ci->target_class`.
In addition, `MRB_PROC_TARGET_CLASS(ci->proc)` is always set.
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`.
Yukihiro "Matz" Matsumoto