On Fri, Jul 21, 2017 at 04:09:11PM +0200, Aleksandar Markovic wrote:
> From: Aleksandar Markovic <aleksandar.markovic@xxxxxxxxxx>
>
> Fix the cases of <MADDF|MSUBF>.<D|S> when any of two multiplicands is
> +0 or -0, and the third input is also +0 or -0. Depending on the signs
> of inputs, certain special cases must be handled.
>
> The relevant example:
>
> MADDF.S fd,fs,ft:
> If fs contains +0.0, ft contains -0.0, and fd contains 0.0, fd is
> going to contain +0.0 (without this patch, it used to contain -0.0).
>
Usual fixes/stable comments.
> Signed-off-by: Miodrag Dinic <miodrag.dinic@xxxxxxxxxx>
> Signed-off-by: Goran Ferenc <goran.ferenc@xxxxxxxxxx>
> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@xxxxxxxxxx>
Patch looks correct to me.
Reviewed-by: James Hogan <james.hogan@xxxxxxxxxx>
Cheers
James
> ---
> arch/mips/math-emu/dp_maddf.c | 8 ++++++++
> arch/mips/math-emu/sp_maddf.c | 8 ++++++++
> 2 files changed, 16 insertions(+)
>
> diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c
> index 45f815d..b8b2c17 100644
> --- a/arch/mips/math-emu/dp_maddf.c
> +++ b/arch/mips/math-emu/dp_maddf.c
> @@ -113,6 +113,14 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
> case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
> if (zc == IEEE754_CLASS_INF)
> return ieee754dp_inf(zs);
> + /* Handle cases +0 + (-0) and similar ones. */
> + if (zc == IEEE754_CLASS_ZERO) {
> + if ((!(flags & maddf_negate_product) && (zs == (xs ^ ys))) ||
> + ((flags & maddf_negate_product) && (zs != (xs ^ ys))))
> + return z;
> + else
> + return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
> + }
> /* Multiplication is 0 so just return z */
> return z;
>
> diff --git a/arch/mips/math-emu/sp_maddf.c b/arch/mips/math-emu/sp_maddf.c
> index 76856d7..cb8597b 100644
> --- a/arch/mips/math-emu/sp_maddf.c
> +++ b/arch/mips/math-emu/sp_maddf.c
> @@ -114,6 +114,14 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
> case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
> if (zc == IEEE754_CLASS_INF)
> return ieee754sp_inf(zs);
> + /* Handle cases +0 + (-0) and similar ones. */
> + if (zc == IEEE754_CLASS_ZERO) {
> + if ((!(flags & maddf_negate_product) && (zs == (xs ^ ys))) ||
> + ((flags & maddf_negate_product) && (zs != (xs ^ ys))))
> + return z;
> + else
> + return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD);
> + }
> /* Multiplication is 0 so just return z */
> return z;
>
> --
> 2.7.4
>
Attachment:
signature.asc
Description: Digital signature
