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| author |   Christophe Leroy <christophe.leroy@csgroup.eu> | 2022-02-11 09:51:32 +0100 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2022-03-08 22:33:03 +1100 |
| commit | 0b0057cc4193c7cd9c0829a440e4901b29ce4ff8 (patch) | |
| tree | 284a6e964c2b9961fbdc1556dc877785770e48ba /arch/powerpc/include/asm/bitops.h | |
| parent | powerpc: declare unmodified attribute_group usages const (diff) | |
| download | linux-dev-0b0057cc4193c7cd9c0829a440e4901b29ce4ff8.tar.xz linux-dev-0b0057cc4193c7cd9c0829a440e4901b29ce4ff8.zip | |
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 <fls>:
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 <fls>
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 <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/adc9c9d6378f6b5008246ca717993d7870188efb.1644569473.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/include/asm/bitops.h')
| -rw-r--r-- | arch/powerpc/include/asm/bitops.h | 4 |
1 files 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; |