From: david.laight.linux@gmail.com
To: Nathan Chancellor <nathan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Yury Norov <yury.norov@gmail.com>,
Lucas De Marchi <lucas.demarchi@intel.com>,
Jani Nikula <jani.nikula@intel.com>,
Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: David Laight <david.laight.linux@gmail.com>
Subject: [PATCH next 01/14] overflow: Reduce expansion of __type_max()
Date: Wed, 21 Jan 2026 14:57:18 +0000 [thread overview]
Message-ID: <20260121145731.3623-2-david.laight.linux@gmail.com> (raw)
In-Reply-To: <20260121145731.3623-1-david.laight.linux@gmail.com>
From: David Laight <david.laight.linux@gmail.com>
Change '(x - 1) + x' to '2 * (x - 1) + 1' to avoid expanding the
non-trivial __type_half_max() twice.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
include/linux/overflow.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index 736f633b2d5f..4f014d55ab25 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -31,7 +31,7 @@
* credit to Christian Biere.
*/
#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
-#define __type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
+#define __type_max(T) ((T)(2 * (__type_half_max(T) - 1) + 1))
#define type_max(t) __type_max(typeof(t))
#define __type_min(T) ((T)((T)-type_max(T)-(T)1))
#define type_min(t) __type_min(typeof(t))
--
2.39.5
next prev parent reply other threads:[~2026-01-21 14:58 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-21 14:57 [PATCH next 00/14] bits: De-bloat expansion of GENMASK() david.laight.linux
2026-01-21 14:57 ` david.laight.linux [this message]
2026-01-21 20:59 ` [PATCH next 01/14] overflow: Reduce expansion of __type_max() Kees Cook
2026-02-02 16:45 ` Yury Norov
2026-01-21 14:57 ` [PATCH next 02/14] kbuild: Add W=c for additional compile time checks david.laight.linux
2026-02-02 18:33 ` Yury Norov
2026-02-02 20:07 ` David Laight
2026-02-03 4:47 ` Nathan Chancellor
2026-02-03 11:14 ` David Laight
2026-02-03 19:41 ` Yury Norov
2026-01-21 14:57 ` [PATCH next 03/14] media: videobuf2-core: Use static_assert() for sanity check david.laight.linux
2026-01-21 14:57 ` [PATCH next 04/14] media: atomisp: " david.laight.linux
2026-01-21 14:57 ` [PATCH next 05/14] ixgbevf: Use C test for PAGE_SIZE > IXGBE_MAX_DATA_PER_TXD david.laight.linux
2026-01-23 15:44 ` Simon Horman
2026-01-21 14:57 ` [PATCH next 06/14] asm-generic: include linux/bits.h not vdso/bits.h david.laight.linux
2026-01-21 14:57 ` [PATCH next 07/14] x86/tlb: " david.laight.linux
2026-01-21 14:57 ` [PATCH next 08/14] bits: simplify GENMASK_TYPE() david.laight.linux
2026-02-08 2:36 ` Yury Norov
2026-02-09 9:42 ` David Laight
2026-01-21 14:57 ` [PATCH next 09/14] bits: Change BIT_U8/16() and GENMASK_U8/16() to have unsigned values david.laight.linux
2026-01-21 14:57 ` [PATCH next 10/14] bits: Fix assmebler expansions of GENMASK_Uxx() and BIT_Uxx() david.laight.linux
2026-02-08 3:31 ` Yury Norov
2026-02-08 11:42 ` David Laight
2026-02-08 21:20 ` Yury Norov
2026-02-08 22:27 ` David Laight
2026-01-21 14:57 ` [PATCH next 11/14] bit: Strengthen compile-time tests in GENMASK() and BIT() david.laight.linux
2026-01-21 18:43 ` Vincent Mailhol
2026-01-21 19:14 ` David Laight
2026-01-22 1:11 ` kernel test robot
2026-01-22 10:25 ` David Laight
2026-01-22 20:10 ` David Laight
2026-01-22 4:41 ` kernel test robot
2026-01-22 10:33 ` David Laight
2026-01-22 14:26 ` Andy Shevchenko
2026-01-22 14:55 ` David Laight
2026-01-23 1:25 ` Philip Li
2026-01-23 8:01 ` Vincent Mailhol
2026-01-23 8:11 ` Andy Shevchenko
2026-01-23 8:20 ` Al Viro
2026-01-23 8:24 ` Andy Shevchenko
2026-01-23 8:32 ` Vincent Mailhol
2026-01-23 8:46 ` Andy Shevchenko
2026-01-23 1:24 ` Philip Li
2026-01-21 14:57 ` [PATCH next 12/14] bits: move the defitions of BIT() and BIT_ULL() back to linux/bits.h david.laight.linux
2026-01-21 15:17 ` Thomas Weißschuh
2026-01-21 19:24 ` David Laight
2026-01-22 7:39 ` Thomas Weißschuh
2026-01-22 0:50 ` kernel test robot
2026-01-22 1:23 ` kernel test robot
2026-01-22 10:30 ` David Laight
2026-02-07 22:40 ` Thomas Gleixner
2026-02-08 4:23 ` Yury Norov
2026-01-21 14:57 ` [PATCH next 13/14] test_bits: Change all the tests to be compile-time tests david.laight.linux
2026-02-08 4:37 ` Yury Norov
2026-02-08 11:32 ` David Laight
2026-01-21 14:57 ` [PATCH next 14/14] test_bits: include some invalid input tests for GENMASK_INPUT_CHECK() david.laight.linux
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