Re: Check results on PowerPC

[Paul Cercueil]

Hi Paulo,

Le ven., août 19 2022 at 09:44:50 -0300, Paulo César Pereira de 
Andrade <paulo.cesar.pereira.de.andrade@gmail.com> a écrit :
> Em sex., 19 de ago. de 2022 às 04:47, Paul Cercueil
> <paul@crapouillou.net> escreveu:
>
>   Hi Paul,
>
> >  >>  I don't know if that's a known thing, but there are several
> >  >> breakages
> >  >>  on PowerPC (PPC32BE):
> >  >
> >  >   What operating system?
> >
> >  Linux, under qemu-user.
> >
> >  >>  FAIL: 3to2
> ...
>
>   Please confirm running:
>
> $ cpp -dM /dev/null | grep _CALL
>
> prints a definition for _CALL_SYSV

I do get _CALL_SYSV set to 1, yes.

>   Maybe it is some different processor that lacks some feature,
> or uses a different abi.
>
>   It might also be a problem with glibc, as it might be an issue
> only with variadic functions, in this case, printf, that might be
> expecting float values in float registers for variadic arguments.
>
>   If yes, please test this reduced test:
>
> """
> .data    32
> dfmt:
> .c    "%1.0f\n"
>
> .code
>     jmpi main
>
> #define def_test_double(a, b, c)        \
>     name test_double_##a##_##b##_##c    \
> test_double_##a##_##b##_##c:            \
>     prolog                    \
>     arg_d $d0                \
>     arg_d $d1                \
>     getarg_d %b $d0                \
>     getarg_d %c $d1                \
>     subr_d %a %b %c                \
>     retr_d %a                \
>     epilog
> #define test_double(a, b, c, x, y)        \
>     prepare                    \
>         pushargi_d x            \
>         pushargi_d y            \
>     finishi test_double_##a##_##b##_##c    \
>     retval_d %f0                \
>     prepare                    \
>         pushargi dfmt            \
>         ellipsis            \
>         pushargr_d %f0            \
>     finishi @printf
>
> def_test_double(f0, f0, f0)
>
>     name main
> main:
>     prolog
>     test_double(f0, f0, f0, 3.0, 2.0)
>     ret
>     epilog
> """
>
> and run it as:
>
> $ cd check
> $ make debug
> ...
> (gdb) break _jit_emit
> (gdb) run test.tst  # << assuming you called the sample file test.tst
> ...
> (gdb) finish
> (gdb) x/48i _jit.code.ptr
>
>   Please copy&paste the output.

So I could not test it with the 'make debug' GDB instance because I'm 
running things in qemu-user, so my host's GDB is for x86_64 while my 
check/lightning binary is ppc.

When I run the test program like this: 'check/lightning check/test.tst'
It just prints '0'.

I believe I'll need to cross-compile GDB to ppc and run it with 
qemu-user.

Cheers,
-Paul

>   You might truncate it as it should be less than 48 instructions.
>
> >  Actually I tested at the lightning-2.1.3 tag now, and these tests 
> > fail
> >  as well.
> >
> >  >   Apparently it is an issue with floating point registers.
> >
> >  I think so too.
> >
> >  Cheers,
> >  -Paul