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From: David Laight <David.Laight@ACULAB.COM>
To: "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>, "'Linus
 Torvalds'" <torvalds@linux-foundation.org>, 'Netdev'
	<netdev@vger.kernel.org>, "'dri-devel@lists.freedesktop.org'"
	<dri-devel@lists.freedesktop.org>
CC: 'Andy Shevchenko' <andriy.shevchenko@linux.intel.com>, 'Andrew Morton'
	<akpm@linux-foundation.org>, "'Matthew Wilcox (Oracle)'"
	<willy@infradead.org>, 'Christoph Hellwig' <hch@infradead.org>, "'Dan
 Carpenter'" <dan.carpenter@linaro.org>, 'Linus Walleij'
	<linus.walleij@linaro.org>, "'David S . Miller'" <davem@davemloft.net>,
	"'linux-btrfs@vger.kernel.org'" <linux-btrfs@vger.kernel.org>, 'Jens Axboe'
	<axboe@kernel.dk>
Subject: RE: [PATCH next 00611] minmax: Remove 'constexpr' check from
 __careful_clamp()
Thread-Topic: [PATCH next 00611] minmax: Remove 'constexpr' check from
 __careful_clamp()
Thread-Index: AdpSIH76BAHML8iRQIeOmBtN5r1qZw==
Date: Sun, 28 Jan 2024 19:30:32 +0000
Message-ID: <f353164c5fe8483399ffc5200f21b970@AcuMS.aculab.com>
References: <0ca26166dd2a4ff5a674b84704ff1517@AcuMS.aculab.com>
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Nothing requires that clamp() return a constant expression.
The logic to do so significantly increases the .i file.
Remove the check and directly expand __clamp_once() from clamp_t()
since the type check can't fail.

Signed-off-by: David Laight <david.laight@aculab.com>
---
 include/linux/minmax.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 111c52a14fe5..5c7fce76abe5 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -141,12 +141,10 @@
 =09=09"clamp() low limit " #lo " greater than high limit " #hi);=09\
 =09__clamp(__val_##uniq, __lo_##uniq, __hi_##uniq); })
=20
-#define __careful_clamp(val, lo, hi, uniq)=09=09=09=09\
-=09__builtin_choose_expr(__is_constexpr((val) - (lo) + (hi)),=09\
-=09=09__clamp(val, lo, hi),=09=09=09=09=09\
-=09=09({ _Static_assert(__types_ok(val, lo), "clamp() 'lo' signedness erro=
r");=09\
-=09=09_Static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error")=
;=09\
-=09=09__clamp_once(val, lo, hi, uniq); }))
+#define __careful_clamp(val, lo, hi, uniq) ({=09=09=09=09=09\
+=09_Static_assert(__types_ok(val, lo), "clamp() 'lo' signedness error");=
=09\
+=09_Static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error");=
=09\
+=09__clamp_once(val, lo, hi, uniq); })
=20
 /**
  * clamp - return a value clamped to a given range with strict typecheckin=
g
@@ -168,7 +166,9 @@
  * This macro does no typechecking and uses temporary variables of type
  * @type to make all the comparisons.
  */
-#define clamp_t(type, val, lo, hi) clamp((type)(val), (type)(lo), (type)(h=
i))
+#define __clamp_t(type, val, lo, hi, uniq) \
+=09__clamp_once((type)(val), (type)(lo), (type)(hi), uniq)
+#define clamp_t(type, val, lo, hi) __clamp_t(type, val, lo, hi, __COUNTER_=
_)
=20
 /**
  * clamp_val - return a value clamped to a given range using val's type
--=20
2.17.1

-
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