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Yup. I wasn't much helpful here.
Is it the case that recursive functions are somehow less possible to optimize with luajit (pulling this off my ass really, so don't trust it).
I've looked at latest luajit (I'm always syncing up to latest), and the "FYI: FastFunc pairs" is the NYIFF code, which I think is only being produced by recff_nyi, and grep on who's doing that reveals this: 

malkia ~/p/luajit $ git grep recff_nyi | grep -vi recff_nyiu
src/buildvm_lib.c:	    "recff_nyi,\n"
src/lj_crecord.h:#define recff_cdata_index	recff_nyi
src/lj_crecord.h:#define recff_cdata_call	recff_nyi
src/lj_crecord.h:#define recff_cdata_arith	recff_nyi
src/lj_crecord.h:#define recff_clib_index	recff_nyi
src/lj_crecord.h:#define recff_ffi_new		recff_nyi
src/lj_crecord.h:#define recff_ffi_string	recff_nyi
src/lj_crecord.h:#define recff_ffi_copy		recff_nyi
src/lj_crecord.h:#define recff_ffi_fill		recff_nyi
src/lj_crecord.h:#define recff_ffi_istype	recff_nyi
src/lj_crecord.h:#define recff_ffi_abi		recff_nyi

these all seems to be only related to FFI stuff.

Now for the blacklisted it seems to be because of the BC_IFUNCF bytecode

void lj_record_ins(jit_State *J) {
.....
  case BC_IFORL:
  case BC_IITERL:
  case BC_ILOOP:
  case BC_IFUNCF:
  case BC_IFUNCV:
    lj_trace_err(J, LJ_TRERR_BLACKL);
    break;
....
}

Seems like IFUNCF stands for Interpretted FUNCtion Fixed args.
I've looked more, but I'm no Mike Pall... I just have a feeling that recursion makes it goes back to interpretter mode.
And it's not hard to turn any recursive code to non-recursive - by simply maintaining alternative stack for the arguments - I might try it out just for fun! 

Cheers!


On 8/26/11 9:31 AM, Alexander Gladysh wrote:

On Fri, Aug 26, 2011 at 20:12, Alexander Gladysh<agladysh@gmail.com>  wrote:

On Sun, Aug 21, 2011 at 05:03, Dimiter "malkia" Stanev<malkia@gmail.com>
  wrote:



Here is a little bit more optimized version.



<...>



For the record, here are the reproducible luamarca benchmark results:
$ KBENCH_INTERPRETERS=luajit2 ./run_benchmark.sh bench/tclone.lua 1e6
Results:
luajit2
-------------------------------------------------------------------
                 name |     rel | abs s / iter = us (1e-6 s) / iter
-------------------------------------------------------------------
              tclone5 |  1.0000 |  20.19 /    1000000 = 20.190000 us
              tclone2 |  1.1620 |  23.46 /    1000000 = 23.460000 us
           lua_nucleo |  1.3150 |  26.55 /    1000000 = 26.550000 us



The code is here:
https://github.com/agladysh/luamarca/blob/master/bench/tclone.lua


...But LJ2 still blacklists the tclone5() trace, so both my original
questions still stand.

The reason for that is probably this:

---- TRACE 1 abort tclone.lua:108 -- NYI: FastFunc pairs

Mike, please, any input?

Thanks,
Alexander.

luamarca$ luajit2 -jv -jdump bench.lua bench/tclone.lua tclone5 1e5
...

---- TRACE 1 start tclone.lua:96
0001  TGETV    3   1   0
0002  ISF          3
0003  JMP      4 =>  0007
0007  ISNEN    2   0      ; 128
0008  JMP      3 =>  0012
0012  TNEW     3   0
0013  UGET     4   1      ; pairs
0014  MOV      5   0
0015  CALL     4   4   2
0000  . FUNCC               ; pairs
---- TRACE 1 abort tclone.lua:108 -- NYI: FastFunc pairs

---- TRACE 1 start tclone.lua:238
0001  UGET     0   0      ; tclone5
0002  UGET     1   1      ; DATA
0003  CALL     0   2   2
0000  . FUNCF    5          ; tclone.lua:129
0001  . UGET     1   0      ; type
0002  . MOV      2   0
0003  . CALL     1   2   2
0000  . . FUNCC               ; type
0004  . ISNES    1   0      ; "table"
0005  . JMP      1 =>  0011
0006  . UGET     1   1      ; impl
0007  . MOV      2   0
0008  . TNEW     3   0
0009  . KSHORT   4   1
0010  . CALLT    1   4
0000  . IFUNCF  14          ; tclone.lua:96
---- TRACE 1 abort tclone.lua:96 -- blacklisted
...