From 0b0057cc4193c7cd9c0829a440e4901b29ce4ff8 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 11 Feb 2022 09:51:32 +0100 Subject: [PATCH] powerpc/bitops: Force inlining of fls() Building a kernel with CONFIG_CC_OPTIMISE_FOR_SIZE leads to the following functions being copied several times in vmlinux: 31 times __ilog2_u32() 34 times fls() Disassembly follows: c00f476c : c00f476c: 7c 63 00 34 cntlzw r3,r3 c00f4770: 20 63 00 20 subfic r3,r3,32 c00f4774: 4e 80 00 20 blr c00f4778 <__ilog2_u32>: c00f4778: 94 21 ff f0 stwu r1,-16(r1) c00f477c: 7c 08 02 a6 mflr r0 c00f4780: 90 01 00 14 stw r0,20(r1) c00f4784: 4b ff ff e9 bl c00f476c c00f4788: 80 01 00 14 lwz r0,20(r1) c00f478c: 38 63 ff ff addi r3,r3,-1 c00f4790: 7c 08 03 a6 mtlr r0 c00f4794: 38 21 00 10 addi r1,r1,16 c00f4798: 4e 80 00 20 blr When forcing inlining of fls(), we get c0008b80 <__ilog2_u32>: c0008b80: 7c 63 00 34 cntlzw r3,r3 c0008b84: 20 63 00 1f subfic r3,r3,31 c0008b88: 4e 80 00 20 blr vmlinux size gets reduced by 1 kbyte with that change. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/adc9c9d6378f6b5008246ca717993d7870188efb.1644569473.git.christophe.leroy@csgroup.eu --- arch/powerpc/include/asm/bitops.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/bitops.h b/arch/powerpc/include/asm/bitops.h index ea5d27dda8cf..344fba3b16eb 100644 --- a/arch/powerpc/include/asm/bitops.h +++ b/arch/powerpc/include/asm/bitops.h @@ -287,7 +287,7 @@ static inline void arch___clear_bit_unlock(int nr, volatile unsigned long *addr) * fls: find last (most-significant) bit set. * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. */ -static inline int fls(unsigned int x) +static __always_inline int fls(unsigned int x) { int lz; @@ -305,7 +305,7 @@ static inline int fls(unsigned int x) * 32-bit fls calls. */ #ifdef CONFIG_PPC64 -static inline int fls64(__u64 x) +static __always_inline int fls64(__u64 x) { int lz;