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Message-Id: <1454615136-32308-2-git-send-email-dvlasenk@redhat.com>
Date: Thu, 4 Feb 2016 20:45:35 +0100
From: Denys Vlasenko <dvlasenk@...hat.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: Denys Vlasenko <dvlasenk@...hat.com>, Thomas Graf <tgraf@...g.ch>,
Peter Zijlstra <peterz@...radead.org>,
David Rientjes <rientjes@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH] 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:
<get_unaligned_be16> (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
<get_unaligned_be32> (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
<get_unaligned_be64> (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 <dvlasenk@...hat.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Graf <tgraf@...g.ch>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org
---
include/uapi/linux/byteorder/big_endian.h | 24 ++++++++++++------------
include/uapi/linux/byteorder/little_endian.h | 24 ++++++++++++------------
include/uapi/linux/swab.h | 10 +++++-----
3 files changed, 29 insertions(+), 29 deletions(-)
diff --git a/include/uapi/linux/byteorder/big_endian.h b/include/uapi/linux/byteorder/big_endian.h
index 6723744..cdab17a 100644
--- a/include/uapi/linux/byteorder/big_endian.h
+++ b/include/uapi/linux/byteorder/big_endian.h
@@ -40,51 +40,51 @@
#define __cpu_to_be16(x) ((__force __be16)(__u16)(x))
#define __be16_to_cpu(x) ((__force __u16)(__be16)(x))
-static inline __le64 __cpu_to_le64p(const __u64 *p)
+static __always_inline __le64 __cpu_to_le64p(const __u64 *p)
{
return (__force __le64)__swab64p(p);
}
-static inline __u64 __le64_to_cpup(const __le64 *p)
+static __always_inline __u64 __le64_to_cpup(const __le64 *p)
{
return __swab64p((__u64 *)p);
}
-static inline __le32 __cpu_to_le32p(const __u32 *p)
+static __always_inline __le32 __cpu_to_le32p(const __u32 *p)
{
return (__force __le32)__swab32p(p);
}
-static inline __u32 __le32_to_cpup(const __le32 *p)
+static __always_inline __u32 __le32_to_cpup(const __le32 *p)
{
return __swab32p((__u32 *)p);
}
-static inline __le16 __cpu_to_le16p(const __u16 *p)
+static __always_inline __le16 __cpu_to_le16p(const __u16 *p)
{
return (__force __le16)__swab16p(p);
}
-static inline __u16 __le16_to_cpup(const __le16 *p)
+static __always_inline __u16 __le16_to_cpup(const __le16 *p)
{
return __swab16p((__u16 *)p);
}
-static inline __be64 __cpu_to_be64p(const __u64 *p)
+static __always_inline __be64 __cpu_to_be64p(const __u64 *p)
{
return (__force __be64)*p;
}
-static inline __u64 __be64_to_cpup(const __be64 *p)
+static __always_inline __u64 __be64_to_cpup(const __be64 *p)
{
return (__force __u64)*p;
}
-static inline __be32 __cpu_to_be32p(const __u32 *p)
+static __always_inline __be32 __cpu_to_be32p(const __u32 *p)
{
return (__force __be32)*p;
}
-static inline __u32 __be32_to_cpup(const __be32 *p)
+static __always_inline __u32 __be32_to_cpup(const __be32 *p)
{
return (__force __u32)*p;
}
-static inline __be16 __cpu_to_be16p(const __u16 *p)
+static __always_inline __be16 __cpu_to_be16p(const __u16 *p)
{
return (__force __be16)*p;
}
-static inline __u16 __be16_to_cpup(const __be16 *p)
+static __always_inline __u16 __be16_to_cpup(const __be16 *p)
{
return (__force __u16)*p;
}
diff --git a/include/uapi/linux/byteorder/little_endian.h b/include/uapi/linux/byteorder/little_endian.h
index d876736..4b93f2b 100644
--- a/include/uapi/linux/byteorder/little_endian.h
+++ b/include/uapi/linux/byteorder/little_endian.h
@@ -40,51 +40,51 @@
#define __cpu_to_be16(x) ((__force __be16)__swab16((x)))
#define __be16_to_cpu(x) __swab16((__force __u16)(__be16)(x))
-static inline __le64 __cpu_to_le64p(const __u64 *p)
+static __always_inline __le64 __cpu_to_le64p(const __u64 *p)
{
return (__force __le64)*p;
}
-static inline __u64 __le64_to_cpup(const __le64 *p)
+static __always_inline __u64 __le64_to_cpup(const __le64 *p)
{
return (__force __u64)*p;
}
-static inline __le32 __cpu_to_le32p(const __u32 *p)
+static __always_inline __le32 __cpu_to_le32p(const __u32 *p)
{
return (__force __le32)*p;
}
-static inline __u32 __le32_to_cpup(const __le32 *p)
+static __always_inline __u32 __le32_to_cpup(const __le32 *p)
{
return (__force __u32)*p;
}
-static inline __le16 __cpu_to_le16p(const __u16 *p)
+static __always_inline __le16 __cpu_to_le16p(const __u16 *p)
{
return (__force __le16)*p;
}
-static inline __u16 __le16_to_cpup(const __le16 *p)
+static __always_inline __u16 __le16_to_cpup(const __le16 *p)
{
return (__force __u16)*p;
}
-static inline __be64 __cpu_to_be64p(const __u64 *p)
+static __always_inline __be64 __cpu_to_be64p(const __u64 *p)
{
return (__force __be64)__swab64p(p);
}
-static inline __u64 __be64_to_cpup(const __be64 *p)
+static __always_inline __u64 __be64_to_cpup(const __be64 *p)
{
return __swab64p((__u64 *)p);
}
-static inline __be32 __cpu_to_be32p(const __u32 *p)
+static __always_inline __be32 __cpu_to_be32p(const __u32 *p)
{
return (__force __be32)__swab32p(p);
}
-static inline __u32 __be32_to_cpup(const __be32 *p)
+static __always_inline __u32 __be32_to_cpup(const __be32 *p)
{
return __swab32p((__u32 *)p);
}
-static inline __be16 __cpu_to_be16p(const __u16 *p)
+static __always_inline __be16 __cpu_to_be16p(const __u16 *p)
{
return (__force __be16)__swab16p(p);
}
-static inline __u16 __be16_to_cpup(const __be16 *p)
+static __always_inline __u16 __be16_to_cpup(const __be16 *p)
{
return __swab16p((__u16 *)p);
}
diff --git a/include/uapi/linux/swab.h b/include/uapi/linux/swab.h
index 0e011eb..3f10e53 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);
--
1.8.1.4
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