Highlights are:
- `Integrate the blocks `if (!ci->proc || MRB_PROC_CFUNC_P(ci->proc))` and `if (loc.irep == NULL)`.
- Folding some other conditionals.
- Assertions ensure that procs are not aliases.
When irep->refcnt reaches UINT16_MAX, mrb_irep_incref() raises
exception but the function pack_backtrace_i() is called from
mrb_exc_raise() thus causes the infinite loop problem. So this is a
hack-ish workaround by making irep reference to NULL if refcnt reaches
the maximum count. Probably we will address this issue again to make it
better.
The `MRB_TT_BACKTRACE` object has been added for the purpose.
Previously, "use-after-free" could occur because the reference count in `backtrace_location::irep` was not incremented.
fixed#6160
Since we have stop calling mrb_debug_get_position() in each_backtrace(),
we don't need to craft special function count_backtrace(). We just use
each_backtrace() to count the number of backtraces.
Instead of calling `mrb_debug_get_position` in the `each_backtrace`, we
just keep `irep` and `idx` information in the backtrace_location, and
get the exact position in `mrb_unpack_backtrace` which may not be called
if exceptions are handled in the `rescue` clauses.
- In case of `NoMemoryError` exceptions, the error message is now printed directly.
- Replaced `mrb_p()` used by #4250 with `mrb_print_error()`.
ref. squashed commit f1523d2404
ref. subcommit da7d7f881b
ref. subcommit d9c7b6be6e
Internal functions can only be called from within the library.
Functions listed in `mruby/internal.h` can be called from:
* core (src/*.c)
* gems (mrbgems/**/*.c)
But not from the application linked with `libmruby`.
Since the possible values of the backtrace are limited to `nil`, `RData`, and `RAray`, they are now stored as object pointers.
This change saves memory by eliminating the need to use instance variables for common exceptions.
ref. #2485
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.
- Changed the `mrb_callinfo::pc` field to point to itself.
Previously it indicated the return destination of the previous call level.
`mrb_callinfo::pc` will now hold the address to its own `proc->body.irep->iseq`.
- Removed `mrb_callinfo::err` field.
This is because `mrb_callinfo::pc - 1` is semantically the same as the previous `err`.
- The `pc0` and `pc_save` variables in `mrb_vm_exec()` are no longer needed and have been deleted.
- It removes the argument because `cipush()` doesn't need to save the previous `pc`.
Yukihiro "Matz" Matsumoto