On Tue, 2023-11-28 at 11:29 +0800, Jiahao Xu wrote:
> diff --git a/gcc/config/loongarch/predicates.md
> b/gcc/config/loongarch/predicates.md
> index f7796da10b2..9e9ce58cb53 100644
> --- a/gcc/config/loongarch/predicates.md
> +++ b/gcc/config/loongarch/predicates.md
> @@ -235,6 +235,10 @@ (define_predicate "reg_or_1_operand"
> (ior (match_operand 0 "const_1_operand")
> (match_operand 0 "register_operand")))
>
> +(define_predicate "reg_or_vecotr_1_operand"
"vector" instead of "vecotr".
> + (ior (match_operand 0 "const_vector_1_operand")
> + (match_operand 0 "register_operand")))
> +@opindex mrecip
> +@item -mrecip
> +This option enables use of the reciprocal estimate and reciprocal square
> +root estimate instructions with additional Newton-Raphson steps to increase
> +precision instead of doing a divide or square root and divide for
> +floating-point arguments.
> +These instructions are generated only when
> @option{-funsafe-math-optimizations}
> +is enabled together with @option{-ffinite-math-only} and
> +@option{-fno-trapping-math}.
> +Note that while the throughput of the sequence is higher than the throughput
> of
> +the non-reciprocal instruction, the precision of the sequence can be
> decreased
> +by up to 2 ulp (i.e. the inverse of 1.0 equals 0.99999994).
> +
> +@opindex mrecip=opt
We should document that using these options requires the target CPU to
support the frecipe/frsqrte instructions.
--
Xi Ruoyao <xry...@xry111.site>
School of Aerospace Science and Technology, Xidian University
