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From: Igor Munkin via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Sergey Kaplun <skaplun@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH luajit] Fix bytecode register allocation for comparisons.
Date: Tue, 17 Aug 2021 12:24:11 +0300	[thread overview]
Message-ID: <20210817092410.GE5743@tarantool.org> (raw)
In-Reply-To: <20210719073632.12008-1-skaplun@tarantool.org>


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 19.07.21, Sergey Kaplun wrote:
> From: Mike Pall <mike>
> (cherry picked from commit 2f3f07882fb4ad9c64967d7088461b1ca0a25d3a)
> When LuaJIT is build with LJ_FR2 (GC64), information about frame takes
> two slots -- the first takes the TValue with the function to call, the
> second takes the additional frame information. The recording JIT
> machinery works pretty the same -- the function IR_KGC is loaded in the
> first slot, and the second is set to TREF_FRAME value. This value
> should be rewritten after return from a callee. It is done either by the
> return values either this slot is cleared (set to zero) manually with
> the next bytecode with RA dst mode with the assumption, that the dst RA
> takes the next slot after TREF_FRAME, i.e. an earlier instruction uses
> the smallest possible destination register (see `lj_record_ins()` for
> the details).
> Bytecode allocator swaps operands for ISGT and ISGE comparisons.
> When it happens, the aforementioned rule for registers allocations
> may be violated. When it happens, and this chunk is recording, the slot
> with TREF_FRAME is not rewritten (but the next empty slot after
> TREF_FRAME is) during bytecode recording. This leads to JIT slots
> inconsistency and assertion failure in `rec_check_slots()` during
> recording the next bytecode instruction.
> This patch fixes bytecode register allocation by changing the register
> allocation order in case of ISGT and ISGE bytecodes.
> Sergey Kaplun:
> * added the description and the test for the problem
> Resolves tarantool/tarantool#6227
> ---
> Branch: https://github.com/tarantool/luajit/tree/skaplun/gh-6227-fix-bytecode-allocator-for-comp
> Tarantool branch: https://github.com/tarantool/tarantool/tree/skaplun/gh-6227-fix-bytecode-allocator-for-comp
> Issue: https://github.com/tarantool/tarantool/issues/6227
>  src/lj_parse.c                                |  7 +++-
>  ...ytecode-allocator-for-comparisons.test.lua | 41 +++++++++++++++++++
>  2 files changed, 46 insertions(+), 2 deletions(-)
>  create mode 100644 test/tarantool-tests/gh-6227-bytecode-allocator-for-comparisons.test.lua


> -- 
> 2.31.0

Best regards,

      parent reply	other threads:[~2021-08-17  9:49 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19  7:36 Sergey Kaplun via Tarantool-patches
2021-08-01 10:43 ` Igor Munkin via Tarantool-patches
2021-08-01 17:10   ` Sergey Kaplun via Tarantool-patches
2021-08-16  7:20     ` Igor Munkin via Tarantool-patches
2021-08-16 16:40       ` Sergey Kaplun via Tarantool-patches
2021-08-16 16:27         ` Igor Munkin via Tarantool-patches
2021-08-17  7:36           ` Vitaliia Ioffe via Tarantool-patches
2021-08-10 17:03 ` Sergey Ostanevich via Tarantool-patches
2021-08-16 16:44   ` Sergey Kaplun via Tarantool-patches
2021-08-17  9:24 ` Igor Munkin via Tarantool-patches [this message]

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