linux-kernel - [PATCH 2/2] MIPS: enable GENERIC_FIND_FIRST

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Message-Id: <20210225135700.1381396-3-yury.norov@gmail.com>
Date:   Thu, 25 Feb 2021 05:57:00 -0800
From:   Yury Norov <yury.norov@...il.com>
To:     Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Alexander Lobakin <alobakin@...me>,
        Alexey Klimov <aklimov@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mips@...r.kernel.org
Cc:     Yury Norov <yury.norov@...il.com>
Subject: [PATCH 2/2] MIPS: enable GENERIC_FIND_FIRST_BIT

From: Alexander Lobakin <alobakin@...me>

MIPS doesn't have architecture-optimized bitsearching functions,
like find_{first,next}_bit() etc.
It's absolutely harmless to enable GENERIC_FIND_FIRST_BIT as this
functionality is not new at all and well-tested. It provides more
optimized code and saves some .text memory (32 R2):

add/remove: 4/1 grow/shrink: 1/53 up/down: 216/-372 (-156)

Users of for_each_set_bit() like hotpath gic_handle_shared_int()
will also benefit from this.

Suggested-by: Yury Norov <yury.norov@...il.com>
Signed-off-by: Alexander Lobakin <alobakin@...me>
Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 arch/mips/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index d89efba3d8a4..164bdd715d4b 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -26,6 +26,7 @@ config MIPS
 	select GENERIC_ATOMIC64 if !64BIT
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
+	select GENERIC_FIND_FIRST_BIT
 	select GENERIC_GETTIMEOFDAY
 	select GENERIC_IOMAP
 	select GENERIC_IRQ_PROBE
-- 
2.25.1