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Date:   Tue, 25 Jul 2023 12:00:09 +0300
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Yury Norov <yury.norov@gmail.com>
Cc:     Alexander Potapenko <glider@google.com>, catalin.marinas@arm.com,
        will@kernel.org, pcc@google.com, andreyknvl@gmail.com,
        linux@rasmusvillemoes.dk, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, eugenis@google.com,
        syednwaris@gmail.com, william.gray@linaro.org,
        Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH v4 1/5] lib/bitmap: add bitmap_{set,get}_value()
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References: <20230720173956.3674987-1-glider@google.com>
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On Mon, Jul 24, 2023 at 10:04:34PM -0700, Yury Norov wrote:
> On Mon, Jul 24, 2023 at 11:36:36AM +0300, Andy Shevchenko wrote:
> > On Sat, Jul 22, 2023 at 06:57:23PM -0700, Yury Norov wrote:
> > > On Thu, Jul 20, 2023 at 07:39:52PM +0200, Alexander Potapenko wrote:

...

> > > 'GENMASK(nbits - 1, 0) << offset' looks really silly.
> > 
> > But you followed the thread to get a clue why it's written in this form, right?
> 
> Yes, I did. But I don't expect everyone looking at kernel code would spend
> time recovering discussions that explain why that happened. So, at least it
> would be fine to drop a comment.

See also below.

...

>           w = *map & (end < BITS_PER_LONG ? ~GENMASK(end, start) : BITMAP_LAST_WORD_MASK(start));

This GENMASK() may generate worse code as compiler uses more instructions
instead of simple approach with the above..

...

> bitmap_write                                   -     271    +271
> my_bitmap_write                                -     248    +248
> bitmap_read                                    -     229    +229

my_ -- means your proposal? Do you mean you have it better in size than original one?

-- 
With Best Regards,
Andy Shevchenko