Re: [PATCH 2/2] MPILIB: Deobfuscate mpi_cmp

David Howells
2015-01-09T11:00:39Z

This looks very reasonable. cc'ing Dmitry for his check.

David
---
Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:

> The condition preceding 'return 1;' makes my head hurt. At this point,
> we know that u and v have the same sign; if they are negative, they
> compare opposite to how their absolute values compare (which
> mpihelp_cmp found for us), otherwise cmp itself is the
> answer. Negating cmp is ok since mpihelp_cmp returns {-1,0,1};
> -INT_MIN==INT_MIN won't bite us.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> lib/mpi/mpi-cmp.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/lib/mpi/mpi-cmp.c b/lib/mpi/mpi-cmp.c
> index 3801694240d8..d25e9e96c310 100644
> --- a/lib/mpi/mpi-cmp.c
> +++ b/lib/mpi/mpi-cmp.c
> @@ -61,10 +61,8 @@ int mpi_cmp(MPI u, MPI v)
> if (!usize)
> return 0;
> cmp = mpihelp_cmp(u->d, v->d, usize);
> - if (!cmp)
> - return 0;
> - if ((cmp < 0 ? 1 : 0) == (u->sign ? 1 : 0))
> - return 1;
> - return -1;
> + if (u->sign)
> + return -cmp;
> + return cmp;
> }
> EXPORT_SYMBOL_GPL(mpi_cmp);
> --
> 2.1.3