From: Frank Chang <frank.chang@sifive.com>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
"Peter Maydell" <peter.maydell@linaro.org>,
"open list:RISC-V" <qemu-riscv@nongnu.org>,
"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>,
"Aurelien Jarno" <aurelien@aurel32.net>
Subject: Re: [PATCH] fpu/softfloat: set invalid excp flag for RISC-V muladd instructions
Date: Tue, 20 Apr 2021 09:18:01 +0800 [thread overview]
Message-ID: <CAE_xrPhW1eE_-yLXd3J4vovCKeq3xtHDXB1Dn5kQe3c5gSgjwA@mail.gmail.com> (raw)
In-Reply-To: <448d86ca-28b0-6523-d84b-4f9e867cf01b@linaro.org>
[-- Attachment #1: Type: text/plain, Size: 1074 bytes --]
On Mon, Apr 19, 2021 at 11:28 PM Richard Henderson <
richard.henderson@linaro.org> wrote:
> On 4/18/21 10:56 PM, frank.chang@sifive.com wrote:
> > +#elif defined(TARGET_RISCV)
> > + /*
> > + * For RISC-V, InvalidOp is set when multiplicands are Inf and zero
> > + * and returns default NaN.
> > + */
> > + if (infzero) {
> > + float_raise(float_flag_invalid, status);
> > + return 3;
> > + }
> > +
> > + if (is_nan(a_cls)) {
> > + return 0;
> > + } else if (is_nan(b_cls)) {
> > + return 1;
> > + } else {
> > + return 2;
> > + }
>
> This second half of the function made me go look into the spec to make
> sure you
> had got that selection right. But RISCV is always in default_nan mode, so
> all
> this is unused (and overridden in pick_nan_muladd).
>
> I think for avoidance of confusion, you should use
>
> if (infzero) {
> float_raise(float_flag_invalid, status);
> }
> return 3; /* default nan */
>
>
> r~
>
Sure, I'll update my patch and resend again.
Thanks
Frank Chang
[-- Attachment #2: Type: text/html, Size: 1666 bytes --]
prev parent reply other threads:[~2021-04-20 1:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-19 5:56 [PATCH] fpu/softfloat: set invalid excp flag for RISC-V muladd instructions frank.chang
2021-04-19 15:28 ` Richard Henderson
2021-04-20 1:18 ` Frank Chang [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAE_xrPhW1eE_-yLXd3J4vovCKeq3xtHDXB1Dn5kQe3c5gSgjwA@mail.gmail.com \
--to=frank.chang@sifive.com \
--cc=alex.bennee@linaro.org \
--cc=aurelien@aurel32.net \
--cc=peter.maydell@linaro.org \
--cc=qemu-devel@nongnu.org \
--cc=qemu-riscv@nongnu.org \
--cc=richard.henderson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).