Re: [Tarantool-patches] [PATCH luajit] Fix predict_next() in parser.

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

Sergey,

I've checked the patchset into all long-term branches in
tarantool/luajit and bumped a new version in master, release/2.11 and
release/2.10.

On 15.08.23, Sergey Kaplun via Tarantool-patches wrote:
> From: Mike Pall <mike>
> 
> Reported by Sergey Kaplun.
> 
> (cherry-picked from commit caf7cbc57c945f7b68871ad72abafb2b6e6fb7f5)
> 
> Assume, we have the following Lua code:
> | local _
> | for _ in (nil):foo() do end
> 
> The first part of the bytecode emitted for it is the following:
> | 0001    KNIL     0   1
> | 0002    MOV      2   1
> | 0003    TGETS    1   1   0  ; "foo"
> | 0004    CALL     1   4   2
> 
> The `0001 KNIL` is a result of merging two `KPRI` instructions: one for
> the local variable, one for the slot with `nil` object. During parsing in
> `predict_next()` the second `MOV` bytecode is examined to set `pairs` or
> `next` local variable. But, as far as it moves `nil` value, that isn't
> an actual variable, so it has no the name this leads to the crash.
> 
> This patch adds the check to be sure that `RD` in the `MOV` bytecode is
> an actual variable.
> 
> Sergey Kaplun:
> * added the description and the test for the problem
> 
> Part of tarantool/tarantool#8825
> ---
> 
> Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-1033-fix-parsing-predict-next
> PR: https://github.com/tarantool/tarantool/pull/8987
> Related issues:
> * https://github.com/LuaJIT/LuaJIT/issues/1033
> * https://github.com/tarantool/tarantool/issues/8825
> 
>  src/lj_parse.c                                |  1 +
>  .../lj-1033-fix-parsing-predict-next.test.lua | 30 +++++++++++++++++++
>  2 files changed, 31 insertions(+)
>  create mode 100644 test/tarantool-tests/lj-1033-fix-parsing-predict-next.test.lua
> 

<snipped>

> -- 
> 2.41.0
> 

-- 
Best regards,
IM