From bc27fb68aaad44dd8f5c34924f05721f0abaeec1 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Thu, 17 Mar 2016 14:22:44 -0700 Subject: include/uapi/linux/byteorder, swab: force inlining of some byteswap operations Sometimes gcc mysteriously doesn't inline very small functions we expect to be inlined. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122 With this .config: http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os, the following functions get deinlined many times. Examples of disassembly: (12 copies, 51 calls): 66 8b 07 mov (%rdi),%ax 55 push %rbp 48 89 e5 mov %rsp,%rbp 86 e0 xchg %ah,%al 5d pop %rbp c3 retq (12 copies, 135 calls): 8b 07 mov (%rdi),%eax 55 push %rbp 48 89 e5 mov %rsp,%rbp 0f c8 bswap %eax 5d pop %rbp c3 retq (2 copies, 20 calls): 48 8b 07 mov (%rdi),%rax 55 push %rbp 48 89 e5 mov %rsp,%rbp 48 0f c8 bswap %rax 5d pop %rbp c3 retq <__swab16p> (16 copies, 146 calls): 55 push %rbp 89 f8 mov %edi,%eax 86 e0 xchg %ah,%al 48 89 e5 mov %rsp,%rbp 5d pop %rbp c3 retq <__swab32p> (43 copies, ~560 calls): 55 push %rbp 89 f8 mov %edi,%eax 0f c8 bswap %eax 48 89 e5 mov %rsp,%rbp 5d pop %rbp c3 retq <__swab64p> (21 copies, 119 calls): 55 push %rbp 48 89 f8 mov %rdi,%rax 48 0f c8 bswap %rax 48 89 e5 mov %rsp,%rbp 5d pop %rbp c3 retq <__swab32s> (6 copies, 47 calls): 8b 07 mov (%rdi),%eax 55 push %rbp 48 89 e5 mov %rsp,%rbp 0f c8 bswap %eax 89 07 mov %eax,(%rdi) 5d pop %rbp c3 retq This patch fixes this via s/inline/__always_inline/. Code size decrease after the patch is ~4.5k: text data bss dec hex filename 92202377 20826112 36417536 149446025 8e85d89 vmlinux 92197848 20826112 36417536 149441496 8e84bd8 vmlinux5_swap_after Signed-off-by: Denys Vlasenko Acked-by: Ingo Molnar Cc: Thomas Graf Cc: Peter Zijlstra Cc: David Rientjes Cc: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/uapi/linux/swab.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'include/uapi/linux/swab.h') diff --git a/include/uapi/linux/swab.h b/include/uapi/linux/swab.h index 0e011eb91b5d..3f10e5317b46 100644 --- a/include/uapi/linux/swab.h +++ b/include/uapi/linux/swab.h @@ -151,7 +151,7 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val) * __swab16p - return a byteswapped 16-bit value from a pointer * @p: pointer to a naturally-aligned 16-bit value */ -static inline __u16 __swab16p(const __u16 *p) +static __always_inline __u16 __swab16p(const __u16 *p) { #ifdef __arch_swab16p return __arch_swab16p(p); @@ -164,7 +164,7 @@ static inline __u16 __swab16p(const __u16 *p) * __swab32p - return a byteswapped 32-bit value from a pointer * @p: pointer to a naturally-aligned 32-bit value */ -static inline __u32 __swab32p(const __u32 *p) +static __always_inline __u32 __swab32p(const __u32 *p) { #ifdef __arch_swab32p return __arch_swab32p(p); @@ -177,7 +177,7 @@ static inline __u32 __swab32p(const __u32 *p) * __swab64p - return a byteswapped 64-bit value from a pointer * @p: pointer to a naturally-aligned 64-bit value */ -static inline __u64 __swab64p(const __u64 *p) +static __always_inline __u64 __swab64p(const __u64 *p) { #ifdef __arch_swab64p return __arch_swab64p(p); @@ -232,7 +232,7 @@ static inline void __swab16s(__u16 *p) * __swab32s - byteswap a 32-bit value in-place * @p: pointer to a naturally-aligned 32-bit value */ -static inline void __swab32s(__u32 *p) +static __always_inline void __swab32s(__u32 *p) { #ifdef __arch_swab32s __arch_swab32s(p); @@ -245,7 +245,7 @@ static inline void __swab32s(__u32 *p) * __swab64s - byteswap a 64-bit value in-place * @p: pointer to a naturally-aligned 64-bit value */ -static inline void __swab64s(__u64 *p) +static __always_inline void __swab64s(__u64 *p) { #ifdef __arch_swab64s __arch_swab64s(p); -- cgit v1.2.3-58-ga151