qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: Peter Maydell <peter.maydell@linaro.org>
To: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
Cc: "Richard Henderson" <richard.henderson@linaro.org>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Francisco Iglesias" <frasse.iglesias@gmail.com>,
	"Laurent Vivier" <laurent@vivier.eu>,
	"QEMU Developers" <qemu-devel@nongnu.org>,
	"Andrew Dutcher" <andrew@andrewdutcher.com>,
	bharata@linux.vnet.ibm.com,
	"Aurelien Jarno" <aurelien@aurel32.net>
Subject: Re: [Qemu-devel] [PATCH v2 10/20] fpu/softfloat: define decompose structures
Date: Thu, 18 Jan 2018 15:17:44 +0000	[thread overview]
Message-ID: <CAFEAcA90331Sezm-PwVFrMqP6Fgav0ujJv0Mkt7PAd_9CBrEFA@mail.gmail.com> (raw)
In-Reply-To: <782d052d-f390-1a55-8a73-120753aa1472@amsat.org>

On 18 January 2018 at 14:59, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> My comment was for a previous line:
>
>   uint64_t frac   : 64;
>
> I don't have enough compiler knowledge to be sure how this bitfield is
> interpreted by the compiler. I understood the standard as bitfields are
> for 'unsigned', and for IL32 we have sizeof(unsigned) = 32, so I wonder
> how a :64 bitfield ends (bits >= 32 silently truncated?).

Defining a 64-bit bitfield is a bit pointless (why not just use
uint64_t?) but there's nothing particularly different for IL32P64 here.
The spec says the underlying type is _Bool, signed int, unsigned
into, or an implementation defined type. For QEMU's hosts 'int'
is always 32 bits, so if gcc and clang allow bitfields on a
64-bit type like uint64_t (as an impdef extension) then they
should work on all hosts. (In any case it needs to either work
or give a compiler error, silent truncation isn't an option.)

thanks
-- PMM

  reply	other threads:[~2018-01-18 15:18 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-09 12:22 [Qemu-devel] [PATCH v2 00/20] re-factor softfloat and add fp16 functions Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 01/20] fpu/softfloat: implement float16_squash_input_denormal Alex Bennée
2018-01-12 13:41   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 02/20] include/fpu/softfloat: remove USE_SOFTFLOAT_STRUCT_TYPES Alex Bennée
2018-01-09 12:27   ` Laurent Vivier
2018-01-09 14:12     ` Aurelien Jarno
2018-01-09 14:14       ` Peter Maydell
2018-01-09 14:20         ` Laurent Vivier
2018-01-09 14:43           ` Peter Maydell
2018-01-09 16:45             ` Richard Henderson
2018-01-09 15:25           ` Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 03/20] include/fpu/softfloat: implement float16_abs helper Alex Bennée
2018-01-12 13:42   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 04/20] include/fpu/softfloat: implement float16_chs helper Alex Bennée
2018-01-12 13:43   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 05/20] include/fpu/softfloat: implement float16_set_sign helper Alex Bennée
2018-01-12 13:43   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 06/20] include/fpu/softfloat: add some float16 constants Alex Bennée
2018-01-09 13:27   ` Philippe Mathieu-Daudé
2018-01-09 15:16     ` Alex Bennée
2018-01-12 13:47   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 07/20] fpu/softfloat: propagate signalling NaNs in MINMAX Alex Bennée
2018-01-12 14:04   ` Peter Maydell
2018-01-16 11:31     ` Alex Bennée
2018-01-16 11:53       ` Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 08/20] fpu/softfloat: improve comments on ARM NaN propagation Alex Bennée
2018-01-12 14:07   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 09/20] fpu/softfloat: move the extract functions to the top of the file Alex Bennée
2018-01-12 14:07   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 10/20] fpu/softfloat: define decompose structures Alex Bennée
2018-01-09 17:01   ` Richard Henderson
2018-01-12 14:22   ` Peter Maydell
2018-01-12 16:21   ` Philippe Mathieu-Daudé
2018-01-18 13:08     ` Alex Bennée
2018-01-18 14:26       ` Philippe Mathieu-Daudé
2018-01-18 14:31         ` Peter Maydell
2018-01-18 14:59           ` Philippe Mathieu-Daudé
2018-01-18 15:17             ` Peter Maydell [this message]
2018-01-23 12:00               ` Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 11/20] fpu/softfloat: re-factor add/sub Alex Bennée
2018-01-12 15:57   ` Peter Maydell
2018-01-12 18:30     ` Richard Henderson
2018-01-18 16:43     ` Alex Bennée
2018-01-18 16:47       ` Richard Henderson
2018-01-23 20:05     ` Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 12/20] fpu/softfloat: re-factor mul Alex Bennée
2018-01-09 12:43   ` Philippe Mathieu-Daudé
2018-01-12 16:17   ` Peter Maydell
2018-01-16 10:16     ` Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 13/20] fpu/softfloat: re-factor div Alex Bennée
2018-01-12 16:22   ` Peter Maydell
2018-01-12 18:35     ` Richard Henderson
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 14/20] fpu/softfloat: re-factor muladd Alex Bennée
2018-02-13 15:15   ` Peter Maydell
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 15/20] fpu/softfloat: re-factor round_to_int Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 16/20] fpu/softfloat: re-factor float to int/uint Alex Bennée
2018-01-09 17:12   ` Richard Henderson
2018-01-12 16:36   ` Peter Maydell
2018-01-16 17:06   ` Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 17/20] fpu/softfloat: re-factor int/uint to float Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 18/20] fpu/softfloat: re-factor scalbn Alex Bennée
2018-01-12 16:31   ` Peter Maydell
2018-01-24 12:03     ` Alex Bennée
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 19/20] fpu/softfloat: re-factor minmax Alex Bennée
2018-01-09 17:16   ` Richard Henderson
2018-01-09 12:22 ` [Qemu-devel] [PATCH v2 20/20] fpu/softfloat: re-factor compare Alex Bennée
2018-01-09 17:18   ` Richard Henderson
2018-01-09 13:07 ` [Qemu-devel] [PATCH v2 00/20] re-factor softfloat and add fp16 functions no-reply

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=CAFEAcA90331Sezm-PwVFrMqP6Fgav0ujJv0Mkt7PAd_9CBrEFA@mail.gmail.com \
    --to=peter.maydell@linaro.org \
    --cc=alex.bennee@linaro.org \
    --cc=andrew@andrewdutcher.com \
    --cc=aurelien@aurel32.net \
    --cc=bharata@linux.vnet.ibm.com \
    --cc=f4bug@amsat.org \
    --cc=frasse.iglesias@gmail.com \
    --cc=laurent@vivier.eu \
    --cc=qemu-devel@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).