ref. #5613.
I mentioned in #5540 that there was no reentrant to the virtual machine, but in fact it was still a possibility at that point.
Also, the variable `ci` needs to be recalculated at the same time.
The number of registers used is reduced.
Also, previously `R6` and` R7` were used, which exceeded the limit of `new_irep.nregs = 6`.
This could cause the VM stack to overrun.
The Difference
Since Ruby1.9, the keyword arguments were emulated by Ruby using the hash
object at the bottom of the arguments. But we have gradually moved toward
keyword arguments separated from normal (positinal) arguments.
At the same time, we value compatibility, so that Ruby3.0 keyword
arguments are somewhat compromise. Basically, keyword arguments are
separated from positional arguments, except when the method does not
take any formal keyword arguments, given keyword arguments (packed
in the hash object) are considered as the last argument.
And we also allow non symbol keys in the keyword arguments. In that
case, those keys are just passed in the `**` hash (or raise
`ArgumentError` for unknown keys).
The Instruction Changes
We have changed `OP_SEND` instruction. `OP_SEND` instruction used to
take 3 operands, the register, the symbol, the number of (positional)
arguments. The meaning of the third operand has been changed. It is now
considered as `n|(nk<<4)`, where `n` is the number of positional
arguments, and `nk` is the number of keyword arguments, both occupies
4 bits in the operand.
The number `15` in both `n` and `nk` means variable sized arguments are
packed in the object. Positional arguments will be packed in the array,
and keyword arguments will be packed in the hash object. That means
arguments more than 14 values are always packed in the object.
Arguments information for other instructions (`OP_SENDB` and `OP_SUPER`)
are also changed. It works as the third operand of `OP_SEND`. the
difference between `OP_SEND` and `OP_SENDB` is just trivial. It assigns
`nil` to the block hidden arguments (right after arguments).
The instruction `OP_SENDV` and `OP_SENDVB` are removed. Those
instructions are replaced by `OP_SEND` and `OP_SENDB` respectively with
the `15` (variable sized) argument information.
Calling Convention
When calling a method, the stack elements shall be in the order of the
receiver of the method, positional arguments, keyword arguments and the
block argument. If the number of positional or keyword arugument (`n` or
`nk`) is zero, corresponding arguments will be empty. So when `n=0` and
`nk=0` the stack layout (from bottom to top) will be:
+-----------------------+
| recv | block (or nil) |
+-----------------------+
The last elements `block` should be explicitly filled before `OP_SEND`
or assigned to `nil` by `OP_SENDB` internally. In other words, the
following have exactly same behavior:
OP_SENDB clears `block` implicitly:
```
OP_SENDB reg sym 0
```
OP_SEND clears `block` implicitly:
```
OP_LOADNIL R2
OP_SEND R2 sym 0
```
When calling a method with only positional arguments (n=0..14) without
keyword arguments, the stack layout will be like following:
+--------------------------------------------+
| recv | arg1 | ... | arg_n | block (or nil) |
+--------------------------------------------+
When calling a method with arguments packed in the array (n=15) which
means argument splat (*) is used in the actual arguments, or more than
14 arguments are passed the stack layout will be like following:
+-------------------------------+
| recv | array | block (or nil) |
+-------------------------------+
The number of the actual arguments is determined by the length of the
argument array.
When keyword arguments are given (nk>0), keyword arguments are passed
between positional arguments and the block argument. For example, when
we pass one positional argument `1` and one keyword argument `a: 2`,
the stack layout will be like:
+------------------------------------+
| recv | 1 | :a | 2 | block (or nil) |
+------------------------------------+
Note that keyword arguments consume `2*nk` elements in the stack when
`nk=0..14` (unpacked).
When calling a method with keyword arguments packed in the hash object
(nk=15) which means keyword argument splat (**) is used or more than
14 keyword arguments in the actual arguments, the stack layout will
be like:
+------------------------------+
| recv | hash | block (or nil) |
+------------------------------+
Note for mruby/c
When mruby/c authors try to support new keyword arguments, they need
to handle the new meaning of the argument information operand. If they
choose not to support keyword arguments in mruby/c, it just raise
error when `nk` (taken by `(c>>4)&0xf`) is not zero. And combine
`OP_SENDV` behavior with `OP_SEND` when `n` is `15`.
If they want to support keyword arguments seriously, contact me at
<matz@ruby.or.jp> or `@yukihiro_matz`. I can help you.
They return the checking argument without modification, so the values
are already there. Maybe we should change the return type to `void` but
keep them unchanged for compatibility.
- Removed the `ARGV` macro.
The current path doesn't go into the mruby VM and there's also no need to separate variables.
- Use common functions to check object types.
- Use `mrb_ensure_string_type()` to check the string instead of `mrb_to_str()`.
This is for consistency with array and hash.
- Use `mrb_ensure_array_type()` to check the array instead of `to_ary()`.
- Use `mrb_ensure_hash_type()` to check the hash instead of `to_hash()`.
- Add and use `ensure_class_type()` to check class and module.
- Changed the argument index type from `mrb_int` to `int`.
Even if it is `int16_t`, it is enough.
`mrb_int` is overkill, especially if `MRB_32BIT` and `MRB_INT64` are defined.
This now works with the `+` modifier that can be added after each specifier.
- `nil` is bypassed.
- The `s` and `z` specifiers are received in C as a `const char *`, so adding a `+` modifier will raise an exception.
- The `a` specifier is received in C as `const mrb_value *`, so adding a `+` modifier will raise an exception.
- The `|`, `*`, `&`, `?` and `:` specifiers with `+` modifier raises an exception.
If `!`/`+` exceeds one for each specifier, an exception will occur in the subsequent processing.
This is the same behavior as before.
The previously used `given` variable will be merged into the `pickarg` pointer variable, which points to the argument currently being processed for each loop.
Previously, the `I` specifier only checked if the object was `MRB_TT_ISTRUCT`.
So it was at risk of getting pointers to different C structs if multiple classes were to use the `MRB_TT_ISTRUCT` instance.
Change this behavior and change the C argument corresponding to the `I` specifier to `(void *, struct RClass)`.
This change is not compatible with the previous mruby.
Please note that if the user uses the previous specifications, `SIGSEGV` may occur or the machine stack may be destroyed.
resolve#5527
- ` mrb_block_given_p()` -- The name comes from CRuby's `rb_block_given_p ()`
At the same time, it applies to `f_instance_eval()` and `f_class_eval()` of `mruby-eval`.
The following methods will be made static.
- `Class#new`
- `Proc#call`
- `Kernel#catch`
Previously, static const RProc could not be registered as a method, but this has been changed to allow it.
The `init_SYMBOLS()` function implicitly defined in `MRB_PRESYM_DEFINE_VAR_AND_INITER()` requires some familiarity when trying to find it from the caller.
By introducing `MRB_PRESYM_INIT_SYMBOLS()`, it is possible to find directly from the identifier.
Instead of including `mruby/presym.h` everywhere, we provided the
fallback `mruby/presym.inc` under `include/mruby` directory, and specify
`-I<build-dir>/include` before `-I<top-dir>/include` in `presym.rake`.
So even when someone drops `-I<build-dir>/include` in compiler options,
it just compiles without failure.
This enhances self-containment.
Previously `mrb_context::stack` had the current call level stack, but now it owns it.
The `mrb_context::stack` field, which is no longer needed, will be removed.
#### Before this patch:
```ruby
__send__ #=> wrong number of arguments
{}.default(1,2) #=> wrong number of arguments
```
#### After this patch:
```ruby
__send__ #=> wrong number of arguments (given 0, expected 1+)
{}.default(1,2) #=> wrong number of arguments (given 2, expected 0..1)
```
dearblue