Hi, Sergey,

thanks for the patch! LGTM

Sergey

On 3/2/26 10:52, Sergey Kaplun wrote:
> From: Mike Pall <mike>
>
> Thanks to Sergey Kaplun.
>
> (cherry picked from commit a553b3de243b1ae07bdb21da4bdab77148793f76)
>
> This call returns `true` if the LuaJIT is built in DUALNUM mode, `false`
> otherwise. It may be useful for testing, trace semantics verification
> etc.
>
> All tests where skipconds are relied on the DUALNUM build are updated
> with the use of the `ffi.abi()` instead of previous implementations of
> checks.
>
> Sergey Kaplun:
> * added the description for the feature
>
> Part of tarantool/tarantool#12134
> ---
>   doc/ext_ffi_api.html                                          | 2 ++
>   src/lib_ffi.c                                                 | 3 +++
>   test/tarantool-tests/fix-jit-dump-ir-conv.test.lua            | 4 +++-
>   .../tarantool-tests/lj-1166-error-stitch-oom-ir-buff.test.lua | 3 ++-
>   test/tarantool-tests/lj-859-math-ceil-sign.test.lua           | 3 ++-
>   5 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/doc/ext_ffi_api.html b/doc/ext_ffi_api.html
> index c72191d1..f0a15e7b 100644
> --- a/doc/ext_ffi_api.html
> +++ b/doc/ext_ffi_api.html
> @@ -472,6 +472,8 @@ otherwise. The following parameters are currently defined:
>   <td class="abiparam">uwp</td><td class="abidesc">Universal Windows Platform</td></tr>
>   <tr class="odd">
>   <td class="abiparam">gc64</td><td class="abidesc">64 bit GC references</td></tr>
> +<tr class="odd">
> +<td class="abiparam">dualnum</td><td class="abidesc">Dual-number mode</td></tr>
>   </table>
>   
>   <h3 id="ffi_os"><tt>ffi.os</tt></h3>
> diff --git a/src/lib_ffi.c b/src/lib_ffi.c
> index 7988dab8..ce4813da 100644
> --- a/src/lib_ffi.c
> +++ b/src/lib_ffi.c
> @@ -755,6 +755,9 @@ LJLIB_CF(ffi_abi)	LJLIB_REC(.)
>   #endif
>   #if LJ_GC64
>       "\004gc64"
> +#endif
> +#if LJ_DUALNUM
> +    "\007dualnum"
>   #endif
>     ) >= 0;
>     setboolV(L->top-1, b);
> diff --git a/test/tarantool-tests/fix-jit-dump-ir-conv.test.lua b/test/tarantool-tests/fix-jit-dump-ir-conv.test.lua
> index a2ab8efc..444a3a05 100644
> --- a/test/tarantool-tests/fix-jit-dump-ir-conv.test.lua
> +++ b/test/tarantool-tests/fix-jit-dump-ir-conv.test.lua
> @@ -4,6 +4,8 @@ local test = tap.test('fix-jit-dump-ir-conv'):skipcond({
>     ['Disabled on *BSD due to #4819'] = jit.os == 'BSD',
>   })
>   
> +local ffi = require('ffi')
> +
>   test:plan(2)
>   
>   -- Test file to demonstrate LuaJIT incorrect `jit.dump()` output
> @@ -33,7 +35,7 @@ local traces = jparse.finish()
>   
>   -- Skip tests for DUALNUM mode since it has no conversions (for
>   -- the same cases).
> -local IS_DUALNUM = not traces[1]:has_ir('num SLOAD')
> +local IS_DUALNUM = ffi.abi('dualnum')
>   
>   test:ok(IS_DUALNUM or traces[1]:has_ir('CONV.*int.num index'),
>           'correct dump for index')
> diff --git a/test/tarantool-tests/lj-1166-error-stitch-oom-ir-buff.test.lua b/test/tarantool-tests/lj-1166-error-stitch-oom-ir-buff.test.lua
> index dc21cfbf..00edafbd 100644
> --- a/test/tarantool-tests/lj-1166-error-stitch-oom-ir-buff.test.lua
> +++ b/test/tarantool-tests/lj-1166-error-stitch-oom-ir-buff.test.lua
> @@ -10,10 +10,11 @@ local test = tap.test('lj-1166-error-stitch-oom-ir-buff'):skipcond({
>     ['Disabled on *BSD due to #4819'] = jit.os == 'BSD',
>   })
>   
> +local ffi = require('ffi')
>   local jparse = require('utils').jit.parse
>   local allocinject = require('allocinject')
>   
> -local IS_DUALNUM = tostring(tonumber('-0')) ~= tostring(-0)
> +local IS_DUALNUM = ffi.abi('dualnum')
>   
>   -- XXX: Avoid other traces compilation due to hotcount collisions
>   -- for predictable results.
> diff --git a/test/tarantool-tests/lj-859-math-ceil-sign.test.lua b/test/tarantool-tests/lj-859-math-ceil-sign.test.lua
> index a67de888..6675b5cb 100644
> --- a/test/tarantool-tests/lj-859-math-ceil-sign.test.lua
> +++ b/test/tarantool-tests/lj-859-math-ceil-sign.test.lua
> @@ -1,4 +1,5 @@
>   local tap = require('tap')
> +local ffi = require('ffi')
>   
>   -- Test file to demonstrate the incorrect LuaJIT's behaviour
>   -- for `math.ceil(x)` when argument `x`: -1 < x < -0.5.
> @@ -8,7 +9,7 @@ local test = tap.test('lj-859-math-ceil-sign')
>   
>   test:plan(1)
>   
> -local IS_DUALNUM = tostring(tonumber('-0')) ~= tostring(-0)
> +local IS_DUALNUM = ffi.abi('dualnum')
>   local IS_X86_64 = jit.arch == 'x86' or jit.arch == 'x64'
>   
>   -- Use `tostring()` to compare the sign of the returned value.