Re: [Tarantool-patches] [PATCH luajit] luajit-gdb: support dualnum mode

[Igor Munkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Max,

I've checked the patch into all long-term branches in tarantool/luajit
and bumped a new version in 1.10, 2.7, 2.8 and master.

On 31.07.21, Maxim Kokryashkin wrote:
> For x86/x64 LJ_DUALNUM mode is disabled. But for some other arches
> (arm or arm64, for example) it is enabled by default. luajit-gdb.py
> displays integers in LJ_DUALNUM mode as nan-s.
> 
> As it turned out, luajit-gdb detects those integers as integers, but
> there was a problem with the dumper function itself. The dumper
> function produces output thinking of any input value as of a double.
> However, in DUALNUM mode, integers and floats are stored differently,
> so the `itype` of a float number must be less than `LJ_TISNUM`, and the
> `itype` of an integer must be `LJ_TISNUM`. With this fact in mind, we
> can easily differentiate one from another.
> 
> But in any mode, lua numbers are stored as doubles on the C side, so it
> takes an ugly cast chain on the Python side to perform the some sort of
> the `reinterpret_cast` because the gdb module doesn't have any
> mechanism to get the address of a symbol.
> 
> Closes tarantool/tarantool#6224
> ---
> Github branch: https://github.com/tarantool/luajit/tree/fckxorg/gh-6224-support-dulanum
> Issue: https://github.com/tarantool/tarantool/issues/6224
> For more info, see line 273 in lj_obj.h
> 
>  src/luajit-gdb.py | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 

<snipped>

> -- 
> 2.32.0
> 

-- 
Best regards,
IM