From: Linus Torvalds <torvalds@linuxfoundation.org>
To: David Laight <David.Laight@aculab.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Christoph Hellwig <hch@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Dan Carpenter <dan.carpenter@linaro.org>,
Arnd Bergmann <arnd@kernel.org>,
"Jason@zx2c4.com" <Jason@zx2c4.com>,
"pedro.falcato@gmail.com" <pedro.falcato@gmail.com>,
Mateusz Guzik <mjguzik@gmail.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: Re: [PATCH v2 1/8] minmax: Put all the clamp() definitions together
Date: Sun, 28 Jul 2024 15:22:58 -0700 [thread overview]
Message-ID: <CAHk-=wicdsz3bvy9g7RJ_XvugjxAT0XDitwTQLZmxq40JtHbzg@mail.gmail.com> (raw)
In-Reply-To: <b89b80c7060c43f8a937b8021b4fd7cb@AcuMS.aculab.com>
On Sun, 28 Jul 2024 at 15:14, David Laight <David.Laight@aculab.com> wrote:
>
> Ok, but those can't be used as array sizes or constants.
> So the temporaries don't matter.
No, mut I don't want the insane size explosion from unnecessarily just
forcing it to use min()/max().
> Don't they just work with min() - if not where is the signednes mismatch?
David - this whole discussion is BECAUSE THESE THINGS ARE A TOTAL
DISASTER WHEN USED IN DEEP MACRO EXPANSION.
So no. It does not work - because core macros like HUGETLB_PAGE_ORDER
end up being used deep in the VM layer, and I don't want to see
another stupid multi-ten-kB line just because min() is such a pig.
End result: I'm going to make the rule be that when you do macro
definitions using constants, then "MIN()/MAX()" is preferable simply
because it avoids the insane expansion noise.
Then in normal *code* you should use min() and max(). But not for
things like macro "constants" even if those constants end up being
some computed thing.
Linus
next prev parent reply other threads:[~2024-07-28 22:23 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-28 14:15 [PATCH v2 0/8] minmax: reduce compilation time David Laight
2024-07-28 14:17 ` [PATCH v2 1/8] minmax: Put all the clamp() definitions together David Laight
2024-07-28 17:24 ` Linus Torvalds
2024-07-28 18:11 ` David Laight
2024-07-28 19:55 ` Linus Torvalds
2024-07-28 20:09 ` David Laight
2024-07-28 20:13 ` Linus Torvalds
2024-07-28 20:22 ` David Laight
2024-07-28 20:31 ` Linus Torvalds
2024-07-28 22:13 ` David Laight
2024-07-28 22:22 ` Linus Torvalds [this message]
2024-07-29 8:01 ` David Laight
2024-07-28 21:01 ` Linus Torvalds
2024-07-28 21:53 ` David Laight
2024-07-29 4:15 ` Linus Torvalds
2024-07-29 22:25 ` Arnd Bergmann
2024-07-29 23:21 ` Linus Torvalds
2024-07-30 1:52 ` Linus Torvalds
2024-07-30 3:59 ` Linus Torvalds
2024-07-30 10:10 ` Arnd Bergmann
2024-07-30 14:14 ` Arnd Bergmann
2024-07-30 18:02 ` Linus Torvalds
2024-07-30 19:52 ` Linus Torvalds
2024-07-30 21:47 ` David Laight
2024-07-30 22:44 ` Linus Torvalds
2024-07-30 23:03 ` Linus Torvalds
2024-07-31 8:09 ` David Laight
2024-07-31 10:50 ` Arnd Bergmann
2024-07-31 15:38 ` Linus Torvalds
2024-07-31 15:56 ` David Laight
2024-07-31 16:04 ` Linus Torvalds
2024-12-04 13:15 ` Geert Uytterhoeven
2024-12-04 17:16 ` David Laight
2024-07-30 16:35 ` Linus Torvalds
2024-07-30 16:46 ` Linus Torvalds
2024-07-30 12:03 ` David Laight
2024-07-28 18:23 ` David Laight
2024-07-28 14:18 ` [PATCH v2 2/8] minmax: Use _Static_assert() instead of static_assert() David Laight
2024-07-28 17:51 ` Christophe JAILLET
2024-07-28 18:12 ` David Laight
2024-07-28 14:19 ` [PATCH v2 3/8] compiler.h: Add __if_constexpr(expr, if_const, if_not_const) David Laight
2024-07-28 14:20 ` [PATCH v2 4/8] minmax: Simplify signedness check David Laight
2024-07-28 16:57 ` Linus Torvalds
2024-07-28 18:14 ` David Laight
2024-07-28 20:13 ` David Laight
2024-07-28 14:21 ` [PATCH v2 5/8] minmax: Factor out the zero-extension logic from umin/umax David Laight
2024-07-28 14:22 ` [PATCH v2 6/8] minmax: Optimise _Static_assert() check in clamp() David Laight
2024-07-28 14:23 ` [PATCH v2 7/8] minmax: Use __auto_type David Laight
2024-07-28 16:59 ` Linus Torvalds
2024-07-28 14:24 ` [PATCH v2 8/8] minmax: minmax: Add __types_ok3() and optimise defines with 3 arguments David Laight
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