Re: [Tarantool-patches] [PATCH luajit v1 1/5] build: introduce option LUAJIT_ENABLE_TABLE_BUMP

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

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Hi, Sergey


thanks for the patch! Please see a question below.

On 22.04.2024 11:49, Sergey Kaplun wrote:
> This option enables table bump optimization if sink optimization is
> enabled. The table bump optimization patches the bytecodes with a table
> allocation on the trace recording if the recorded trace exceeds the size
> of the allocated table. This optimization still has some bugs, so it is
> disabled by default. For more details, see the comment in
> <CMakeLists.txt>.
>
> Needed for tarantool/tarantool#9924
> ---
>   CMakeLists.txt | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
>
> diff --git a/CMakeLists.txt b/CMakeLists.txt
> index 2355ce17..52014296 100644
> --- a/CMakeLists.txt
> +++ b/CMakeLists.txt
> @@ -307,6 +307,23 @@ if(LUAJIT_ENABLE_COVERAGE)
>     include(CodeCoverage)
>   endif()
>   
> +# Enable table bump optimization. This optimization patches the
> +# bytecodes with a table allocation on the trace recording if the
> +# recorded trace exceeds the size of the allocated table.
> +# This optimization still has some bugs, so it is disabled by
> +# default. See also:https://github.com/LuaJIT/LuaJIT/issues/606.
> +option(LUAJIT_ENABLE_TABLE_BUMP "Enable table bump optimization" OFF)
> +if(LUAJIT_ENABLE_TABLE_BUMP)
> +  # Within table bump optimization enabled (and due to our
> +  # modification related to metrics), some offsets in `GG_State`
> +  # stop fit in 12bit immediate. Hence, the build failed due to
> +  # the DASM error (DASM_S_RANGE_I).
> +  if(CMAKE_SYSTEM_PROCESSOR STREQUAL "aarch64")
> +    message(FATAL_ERROR "Table Bump optimization is unsupported for aarch64")

Table optimization works on all architectures supported by LuaJIT except 
aarch64, right?


> +  endif()
> +  AppendFlags(TARGET_C_FLAGS -DLUAJIT_ENABLE_TABLE_BUMP)
> +endif()
> +
>   # --- Main source tree ---------------------------------------------------------
>   
>   add_subdirectory(src)

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