Re: [Lightning] jit_qdivr_u trashes JIT_R0 on x86_64

[Paulo César Pereira de Andrade]

Em qui, 22 de ago de 2019 às 16:24, Paul Cercueil <address@hidden> escreveu:
[...]
> This is with the latest master. Good job on the RISC-V port btw :)
Thanks :)

[...]
> I call jit_qdiv(reg1, reg2, reg2, reg1)
> (and also jit_qdiv_u with the same arguments). reg1 and reg2 cannot
> represent the same register.

  Ok. I see it can fail on some ports, actually, probably only on x86.
I will add extra tests for these conditions, and fix any register clobbers
that should be being generated.
  Note that by doing the way you described, it might cause lightning to
generate code to get at least one extra temporary depending on registers
input. It might look clean in the lightning input, but may generate
significantly larger code due to moves to/from %rax and %rdx, as well as
spill reloads.

> Thanks,
> -Paul

Thanks!
Paulo