Re: [PATCH v2 0/7] target/riscv: NaN-boxing for multiple precison

[Alistair Francis]

On Thu, Jul 23, 2020 at 5:28 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> This is my take on Liu Zhiwei's patch set:
> https://patchew.org/QEMU/20200626205917.4545-1-zhiwei_liu@c-sky.com
>
> This differs from Zhiwei's v1 in:
>
>  * If a helper is involved, the helper does the boxing and unboxing.
>
>  * Which leaves only LDW and FSGN*.S as the only instructions that
>    are expanded inline which need to handle nanboxing.
>
>  * All mention of RVD is dropped vs boxing.  This means that an
>    RVF-only cpu will still generate and check nanboxes into the
>    64-bit cpu_fpu slots.  There should be no way an RVF-only cpu
>    can generate an unboxed cpu_fpu value.
>
>    This choice is made to speed up the common case: RVF+RVD, so
>    that we do not have to check whether RVD is enabled.
>
>  * The translate.c primitives take TCGv values rather than fpu
>    regno, which will make it possible to use them with RVV,
>    since v0.9 does proper nanboxing.
>
>  * I have adjusted the current naming to be float32 specific ("*_s"),
>    to avoid confusion with the float16 data type supported by RVV.

Thanks Richard. As Zhiwei has reviewed all of these I have applied
them to the riscv-to-apply.next tree for 5.2.

Alistair

>
>
> r~
>
>
> LIU Zhiwei (2):
>   target/riscv: Clean up fmv.w.x
>   target/riscv: check before allocating TCG temps
>
> Richard Henderson (5):
>   target/riscv: Generate nanboxed results from fp helpers
>   target/riscv: Generalize gen_nanbox_fpr to gen_nanbox_s
>   target/riscv: Generate nanboxed results from trans_rvf.inc.c
>   target/riscv: Check nanboxed inputs to fp helpers
>   target/riscv: Check nanboxed inputs in trans_rvf.inc.c
>
>  target/riscv/internals.h                |  16 ++++
>  target/riscv/fpu_helper.c               | 102 ++++++++++++++++--------
>  target/riscv/insn_trans/trans_rvd.inc.c |   8 +-
>  target/riscv/insn_trans/trans_rvf.inc.c |  99 ++++++++++++++---------
>  target/riscv/translate.c                |  29 +++++++
>  5 files changed, 178 insertions(+), 76 deletions(-)
>
> --
> 2.25.1
>