Re: [Tarantool-patches] [PATCH luajit] Fix compilation of getmetatable() for UDTYPE_IO_FILE

[Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

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Branch: 
https://github.com/tarantool/luajit/tree/ligurio/gh-1279-recording-getmetatable

LJ issue: https://github.com/LuaJIT/LuaJIT/issues/1279


On 07.11.2024 13:51, Sergey Bronnikov wrote:
> From: Sergey Bronnikov<sergeyb@tarantool.org>
>
> The patch fixes a problem with recording `getmetatable()`
> for I/O object: recording of `getmetatable` call with a file
> descriptors represented by userdata object `UDTYPE_IO_FILE`
> (like `io.stdout`) leads to violation of assertion in
> `rec_check_slots`.
>
> Note, the problem was fixed upstream in different manner, see
> commit 5141cbc20c43
> ("Fix compiliation of getmetatable() for UDTYPE_IO_FILE.").
> ---
>   src/lj_record.c                               |  2 +-
>   ...-incorrect-recording-getmetatable.test.lua | 21 +++++++++++++++++++
>   2 files changed, 22 insertions(+), 1 deletion(-)
>   create mode 100644 test/tarantool-tests/lj-1279-incorrect-recording-getmetatable.test.lua
>
> diff --git a/src/lj_record.c b/src/lj_record.c
> index cc97bdf9..7181b72a 100644
> --- a/src/lj_record.c
> +++ b/src/lj_record.c
> @@ -990,7 +990,7 @@ int lj_record_mm_lookup(jit_State *J, RecordIndex *ix, MMS mm)
>       int udtype = udataV(&ix->tabv)->udtype;
>       mt = tabref(udataV(&ix->tabv)->metatable);
>       /* The metatables of special userdata objects are treated as immutable. */
> -    if (udtype != UDTYPE_USERDATA) {
> +    if (udtype > UDTYPE_IO_FILE) {
>         cTValue *mo;
>         if (LJ_HASFFI && udtype == UDTYPE_FFI_CLIB) {
>   	/* Specialize to the C library namespace object. */
> diff --git a/test/tarantool-tests/lj-1279-incorrect-recording-getmetatable.test.lua b/test/tarantool-tests/lj-1279-incorrect-recording-getmetatable.test.lua
> new file mode 100644
> index 00000000..8bf22ca7
> --- /dev/null
> +++ b/test/tarantool-tests/lj-1279-incorrect-recording-getmetatable.test.lua
> @@ -0,0 +1,21 @@
> +local tap = require('tap')
> +
> +local test = tap.test('lj-1279-incorrect-recording-getmetatable')
> +test:plan(1)
> +
> +-- A test file to demonstrate an incorrect recording of
> +-- getmetatable() for I/O handlers.
> +--https://github.com/LuaJIT/LuaJIT/issues/1279
> +
> +jit.opt.start("hotloop=1")
> +
> +local obj = io.stdout
> +local getmetatable = getmetatable
> +
> +for _ = 1, 4 do
> +  _ = getmetatable(obj)
> +end
> +
> +test:ok(true, 'getmetatable() recording is correct')
> +
> +test:done(true)

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