From: David Laight <David.Laight@ACULAB.COM>
To: 'Joe Perches' <joe@perches.com>,
Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Cc: Mark Brown <broonie@kernel.org>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Matti Vaittinen <mazziesaccount@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v2 01/12] regmap-irq: Convert bool bitfields to unsigned int
Date: Fri, 24 Jun 2022 14:28:55 +0000 [thread overview]
Message-ID: <b9da7e05ce96443cacc1df9b2672eb51@AcuMS.aculab.com> (raw)
In-Reply-To: <ca26910886a765dd7edc4815ef90bedbd0f99a95.camel@perches.com>
From: Joe Perches
> Sent: 24 June 2022 14:45
...
> I'm trying to show that conversions of bool:1->unsigned int:1
> as being trivial are not so trivial after all.
>
> It's fairly common to have code like:
>
> [bool] foo.bar = some_value & SETTING;
>
> where some value is tested for a mask/bit and a non-zero is true.
>
> So conversions of foo.bar from bool:1 to unsigned int:1 are not
> wise unless all possible side effects are known.
I can never decide whether:
bool_c = bool_a & bool_b;
can be compiled to a simple 'and' instruction, or requires a
load of instructions in case bool_a and/or bool_b has a non-zero
value without the bottom bit set.
All other C types are cpu register types - so you know what happens.
IMHO bool is an abomination and should not be used :-)
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-06-24 14:29 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-23 21:14 [PATCH v2 00/12] regmap-irq cleanups and refactoring Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 01/12] regmap-irq: Convert bool bitfields to unsigned int Aidan MacDonald
2022-06-23 21:26 ` Andy Shevchenko
2022-06-24 12:11 ` Mark Brown
2022-06-24 12:46 ` Joe Perches
2022-06-24 12:56 ` Mark Brown
2022-06-24 13:05 ` Aidan MacDonald
2022-06-24 13:45 ` Joe Perches
2022-06-24 14:28 ` David Laight [this message]
2022-06-24 14:31 ` Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 02/12] regmap-irq: Remove unused type_reg_stride field Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 03/12] regmap-irq: Cleanup sizeof(...) use in memory allocation Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 04/12] regmap-irq: Remove an unnecessary restriction on type_in_mask Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 05/12] regmap-irq: Remove inappropriate uses of regmap_irq_update_bits() Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 06/12] regmap-irq: Remove mask_writeonly and regmap_irq_update_bits() Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 07/12] regmap-irq: Refactor checks for status bulk read support Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 08/12] regmap-irq: Introduce config registers for irq types Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 09/12] regmap-irq: Deprecate type registers and virtual registers Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 10/12] regmap-irq: Fix inverted handling of unmask registers Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 11/12] regmap-irq: Add get_irq_reg() callback Aidan MacDonald
2022-07-01 16:33 ` Marek Szyprowski
2022-07-03 11:06 ` Aidan MacDonald
2022-06-23 21:14 ` [PATCH v2 12/12] regmap-irq: Deprecate the not_fixed_stride flag Aidan MacDonald
2022-06-30 17:27 ` [PATCH v2 00/12] regmap-irq cleanups and refactoring Mark Brown
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=b9da7e05ce96443cacc1df9b2672eb51@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=aidanmacdonald.0x0@gmail.com \
--cc=andy.shevchenko@gmail.com \
--cc=broonie@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=joe@perches.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mazziesaccount@gmail.com \
--cc=rafael@kernel.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