From: "Junxian Zhu" <zhujunxian@oss.cipunited.com>
To: "Xi Ruoyao" <xry111@xry111.site>, <libc-alpha@sourceware.org>,
<jiaxun.yang@flygoat.com>
Cc: <rongrong@oss.cipunited.com>
Subject: Re: [PATCH 2/2] MIPS: Hard-float rounding instructions support
Date: Thu, 25 Jan 2024 21:58:53 +0800 [thread overview]
Message-ID: <cd381ffb-c515-4068-99f9-b04b7a7057c2@oss.cipunited.com> (raw)
In-Reply-To: <c7d09b8a9bee6380e8579715deca6a5ce375be9e.camel@xry111.site>
在 2023/12/25 18:51, Xi Ruoyao 写道:
> On Mon, 2023-12-25 at 18:35 +0800, Junxian Zhu wrote:
>
> /* snip */
>
>> +/*
>> + * ceil(x)
>> + * Return x rounded toward -inf to integral value
>> + * Method:
>> + * Bit twiddling.
>> + */
>> +
>> +#if ((__mips_fpr == 64) && (__mips_hard_float == 1) && ((__mips == 32 && __mips_isa_rev > 1) || __mips == 64))
>> +#include <sys/regdef.h>
>> +#include <sysdep.h>
>> +#include <libm-alias-double.h>
>> +
>> +ENTRY(__ceil)
>> + .set push
>> + .set noreorder
>> + .set noat
>> +# $f0=ret, $f12=double, a0=int64/int32_h, a1=int32_l, a2=sign, a3=exp
>> +#if __mips == 64
>> + dmfc1 a0, $f12 # assign int64
>> +#else
>> + mfhc1 a0, $f12 # assign int64
>> +#endif
>> + cfc1 t0, $f26
>> + ceil.l.d $f0, $f12
> No, C23 does not allow this function to raise an INEXACT exception, but
> ceil.l.d will do so.
>
> Such optimizations should be performed in GCC which can be controlled by
> the programmer with -std=c23 and/or -f[no-]fp-int-builtin-inexact, not
> in Glibc where we cannot know if the programmer wants to deviate from
> C23.
Recently, I'm still trying to do some optimization for MIPS. I want to
know if I use rounding instructions on MIPS, like |round.l.d|, in
functions with parameters input in FPR and results in GPR, like
|llrint|or |lrint|, will we still face the INEXACT exception and
potentially violate C23?
next prev parent reply other threads:[~2024-01-25 13:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-25 10:35 [PATCH 0/2] Add hard-float rounding instructions support for MIPS architecture Junxian Zhu
2023-12-25 10:35 ` [PATCH 1/2] limb-alias-double.h: Fix missing semicolon Junxian Zhu
2023-12-25 10:35 ` [PATCH 2/2] MIPS: Hard-float rounding instructions support Junxian Zhu
2023-12-25 10:51 ` Xi Ruoyao
2023-12-26 2:37 ` Junxian Zhu
2023-12-26 8:29 ` Xi Ruoyao
2023-12-26 20:12 ` Adhemerval Zanella Netto
2023-12-26 21:50 ` Xi Ruoyao
2023-12-26 22:50 ` Xi Ruoyao
2023-12-27 13:25 ` Adhemerval Zanella Netto
2024-01-02 10:08 ` Junxian Zhu
2024-01-02 9:43 ` Junxian Zhu
2024-01-02 9:57 ` Xi Ruoyao
[not found] ` <5f0f4c83-f6d8-4af3-8cce-e12cd5314da1@oss.cipunited.com>
2024-01-31 9:08 ` Xi Ruoyao
2024-01-25 13:58 ` Junxian Zhu [this message]
2024-01-25 14:37 ` Xi Ruoyao
2023-12-25 12:36 ` YunQiang Su
2023-12-26 2:48 ` Junxian Zhu
2024-01-02 9:51 ` Junxian Zhu
2023-12-29 1:00 ` Joseph Myers
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=cd381ffb-c515-4068-99f9-b04b7a7057c2@oss.cipunited.com \
--to=zhujunxian@oss.cipunited.com \
--cc=jiaxun.yang@flygoat.com \
--cc=libc-alpha@sourceware.org \
--cc=rongrong@oss.cipunited.com \
--cc=xry111@xry111.site \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).