netdev - RE: [PATCH next 00611] minmax: Remove 'constexpr' check from __careful

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Date: Sun, 28 Jan 2024 19:30:32 +0000
From: David Laight <David.Laight@...LAB.COM>
To: "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>, "'Linus
 Torvalds'" <torvalds@...ux-foundation.org>, 'Netdev'
	<netdev@...r.kernel.org>, "'dri-devel@...ts.freedesktop.org'"
	<dri-devel@...ts.freedesktop.org>
CC: 'Andy Shevchenko' <andriy.shevchenko@...ux.intel.com>, 'Andrew Morton'
	<akpm@...ux-foundation.org>, "'Matthew Wilcox (Oracle)'"
	<willy@...radead.org>, 'Christoph Hellwig' <hch@...radead.org>, "'Dan
 Carpenter'" <dan.carpenter@...aro.org>, 'Linus Walleij'
	<linus.walleij@...aro.org>, "'David S . Miller'" <davem@...emloft.net>,
	"'linux-btrfs@...r.kernel.org'" <linux-btrfs@...r.kernel.org>, 'Jens Axboe'
	<axboe@...nel.dk>
Subject: RE: [PATCH next 00611] minmax: Remove 'constexpr' check from
 __careful_clamp()

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@...lab.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 @@
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
 	__clamp(__val_##uniq, __lo_##uniq, __hi_##uniq); })
 
-#define __careful_clamp(val, lo, hi, uniq)				\
-	__builtin_choose_expr(__is_constexpr((val) - (lo) + (hi)),	\
-		__clamp(val, lo, hi),					\
-		({ _Static_assert(__types_ok(val, lo), "clamp() 'lo' signedness error");	\
-		_Static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error");	\
-		__clamp_once(val, lo, hi, uniq); }))
+#define __careful_clamp(val, lo, hi, uniq) ({					\
+	_Static_assert(__types_ok(val, lo), "clamp() 'lo' signedness error");	\
+	_Static_assert(__types_ok(val, hi), "clamp() 'hi' signedness error");	\
+	__clamp_once(val, lo, hi, uniq); })
 
 /**
  * clamp - return a value clamped to a given range with strict typechecking
@@ -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)(hi))
+#define __clamp_t(type, val, lo, hi, uniq) \
+	__clamp_once((type)(val), (type)(lo), (type)(hi), uniq)
+#define clamp_t(type, val, lo, hi) __clamp_t(type, val, lo, hi, __COUNTER__)
 
 /**
  * clamp_val - return a value clamped to a given range using val's type
-- 
2.17.1

-
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