[Tarantool-patches] [PATCH luajit] Fix string.char() recording with no arguments.

[Igor Munkin]

Sergey,

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

On 20.08.21, Sergey Kaplun wrote:
> From: Mike Pall <mike>
> 
> (cherry picked from commit dfa692b746c9de067857d5fc992a41730be3d99a)
> 
> `string.char()` call without arguments yields an empty string. When JIT
> machinery records the aforementioned call it doesn't handle this case.
> Each recording fast function expects 1 result by default.  Hence, when
> return from this call is recorded the framelink slot is used as a
> result. It is loaded into the corresponding slot as an IR with `IRT_NUM`
> type. It leads to assertion failure in `rec_check_slots()`, when a next
> bytecode is recorded, because type of TValue on the stack (`LJ_STR`)
> isn't the same as IR (and TRef) type.
> 
> This patch handles the case without arguments by the loading of IR with
> empty string reference into the corresponding slot.
> 
> Sergey Kaplun:
> * added the description and the test for the problem
> 
> Resolves tarantool/tarantool#6371
> ---
> 
> Branch: https://github.com/tarantool/luajit/tree/skaplun/gh-6371-string-char-no-arg
> Issue: https://github.com/tarantool/tarantool/issues/6371
> Tarantool branch: https://github.com/tarantool/tarantool/tree/skaplun/gh-6371-string-char-no-arg
> Side note: CI is totally red, but AFAICS it's unrelated with my patch.
> Side note: See also Changelog at the Tarantool branch.
> 
>  src/lj_ffrecord.c                             |  2 ++
>  .../gh-6371-string-char-no-arg.test.lua       | 28 +++++++++++++++++++
>  2 files changed, 30 insertions(+)
>  create mode 100644 test/tarantool-tests/gh-6371-string-char-no-arg.test.lua
> 

<snipped>

> -- 
> 2.31.0
> 

-- 
Best regards,
IM