From bceab1431e0789794cbcc8bb71d500a74c8213f2 Mon Sep 17 00:00:00 2001 From: "Russell King (Oracle)" Date: Fri, 29 Jul 2022 16:10:49 +0100 Subject: [PATCH] ARM: findbit: provide more efficient ARMv7 implementation Provide a more efficient ARMv7 implementation to determine the first set bit in the supplied value. Signed-off-by: Russell King (Oracle) --- arch/arm/lib/findbit.S | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm/lib/findbit.S b/arch/arm/lib/findbit.S index 4c584bc4704b8..256e095d490bb 100644 --- a/arch/arm/lib/findbit.S +++ b/arch/arm/lib/findbit.S @@ -170,7 +170,11 @@ ENDPROC(_find_next_bit_be) * One or more bits in the LSB of r3 are assumed to be set. */ .L_found: -#if __LINUX_ARM_ARCH__ >= 5 +#if __LINUX_ARM_ARCH__ >= 7 + rbit r3, r3 @ reverse bits + clz r3, r3 @ count high zero bits + add r0, r2, r3 @ add offset of first set bit +#elif __LINUX_ARM_ARCH__ >= 5 rsb r0, r3, #0 and r3, r3, r0 @ mask out lowest bit set clz r3, r3 @ count high zero bits -- 2.30.2