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
next prev parent 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
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