From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161023AbcBDTpv (ORCPT ); Thu, 4 Feb 2016 14:45:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47435 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966356AbcBDTpt (ORCPT ); Thu, 4 Feb 2016 14:45:49 -0500 From: Denys Vlasenko To: Ingo Molnar Cc: Denys Vlasenko , Thomas Graf , Peter Zijlstra , David Rientjes , Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH] force inlining of unaligned byteswap operations Date: Thu, 4 Feb 2016 20:45:36 +0100 Message-Id: <1454615136-32308-3-git-send-email-dvlasenk@redhat.com> In-Reply-To: <1454615136-32308-1-git-send-email-dvlasenk@redhat.com> References: <1454615136-32308-1-git-send-email-dvlasenk@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: (24 copies, 108 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 (25 copies, 181 calls): 8b 07 mov (%rdi),%eax 55 push %rbp 48 89 e5 mov %rsp,%rbp 0f c8 bswap %eax 5d pop %rbp c3 retq (23 copies, 94 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 (2 copies, 11 calls): 89 f8 mov %edi,%eax 55 push %rbp c1 ef 08 shr $0x8,%edi c1 e0 08 shl $0x8,%eax 09 c7 or %eax,%edi 48 89 e5 mov %rsp,%rbp 66 89 3e mov %di,(%rsi) (8 copies, 43 calls): 55 push %rbp 0f cf bswap %edi 89 3e mov %edi,(%rsi) 48 89 e5 mov %rsp,%rbp 5d pop %rbp c3 retq (26 copies, 157 calls): 55 push %rbp 48 0f cf bswap %rdi 48 89 3e mov %rdi,(%rsi) 48 89 e5 mov %rsp,%rbp 5d pop %rbp c3 retq This patch fixes this via s/inline/__always_inline/. It only affects arches with efficient unaligned access insns, such as x86. (arched which lack such ops do not include linux/unaligned/access_ok.h) Code size decrease after the patch is ~8.5k: text data bss dec hex filename 92197848 20826112 36417536 149441496 8e84bd8 vmlinux 92189231 20826144 36417536 149432911 8e82a4f vmlinux6_unaligned_be_after Signed-off-by: Denys Vlasenko Cc: Ingo Molnar Cc: Thomas Graf Cc: Peter Zijlstra Cc: David Rientjes Cc: Andrew Morton Cc: linux-kernel@vger.kernel.org --- include/linux/unaligned/access_ok.h | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/include/linux/unaligned/access_ok.h b/include/linux/unaligned/access_ok.h index 99c1b4d..33383ca 100644 --- a/include/linux/unaligned/access_ok.h +++ b/include/linux/unaligned/access_ok.h @@ -4,62 +4,62 @@ #include #include -static inline u16 get_unaligned_le16(const void *p) +static __always_inline u16 get_unaligned_le16(const void *p) { return le16_to_cpup((__le16 *)p); } -static inline u32 get_unaligned_le32(const void *p) +static __always_inline u32 get_unaligned_le32(const void *p) { return le32_to_cpup((__le32 *)p); } -static inline u64 get_unaligned_le64(const void *p) +static __always_inline u64 get_unaligned_le64(const void *p) { return le64_to_cpup((__le64 *)p); } -static inline u16 get_unaligned_be16(const void *p) +static __always_inline u16 get_unaligned_be16(const void *p) { return be16_to_cpup((__be16 *)p); } -static inline u32 get_unaligned_be32(const void *p) +static __always_inline u32 get_unaligned_be32(const void *p) { return be32_to_cpup((__be32 *)p); } -static inline u64 get_unaligned_be64(const void *p) +static __always_inline u64 get_unaligned_be64(const void *p) { return be64_to_cpup((__be64 *)p); } -static inline void put_unaligned_le16(u16 val, void *p) +static __always_inline void put_unaligned_le16(u16 val, void *p) { *((__le16 *)p) = cpu_to_le16(val); } -static inline void put_unaligned_le32(u32 val, void *p) +static __always_inline void put_unaligned_le32(u32 val, void *p) { *((__le32 *)p) = cpu_to_le32(val); } -static inline void put_unaligned_le64(u64 val, void *p) +static __always_inline void put_unaligned_le64(u64 val, void *p) { *((__le64 *)p) = cpu_to_le64(val); } -static inline void put_unaligned_be16(u16 val, void *p) +static __always_inline void put_unaligned_be16(u16 val, void *p) { *((__be16 *)p) = cpu_to_be16(val); } -static inline void put_unaligned_be32(u32 val, void *p) +static __always_inline void put_unaligned_be32(u32 val, void *p) { *((__be32 *)p) = cpu_to_be32(val); } -static inline void put_unaligned_be64(u64 val, void *p) +static __always_inline void put_unaligned_be64(u64 val, void *p) { *((__be64 *)p) = cpu_to_be64(val); } -- 1.8.1.4