diff options
| author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-08-04 17:15:15 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-08-05 10:38:09 +0300 |
| commit | d14edb1648221e59fc9fd47127fcc57bf26d759f (patch) | |
| tree | dbefdae5a56c1936b364580ac4b814a2a926b775 /arch/x86/include | |
| parent | 1a1d48a4a8fde49aedc045d894efe67173d59fe0 (diff) | |
| download | linux-d14edb1648221e59fc9fd47127fcc57bf26d759f.tar.xz | |
x86/hweight: Force inlining of __arch_hweight{32,64}()
With this config:
http://busybox.net/~vda/kernel_config_OPTIMIZE_INLINING_and_Os
gcc-4.7.2 generates many copies of these tiny functions:
__arch_hweight32 (35 copies):
55 push %rbp
e8 66 9b 4a 00 callq __sw_hweight32
48 89 e5 mov %rsp,%rbp
5d pop %rbp
c3 retq
__arch_hweight64 (8 copies):
55 push %rbp
e8 5e c2 8a 00 callq __sw_hweight64
48 89 e5 mov %rsp,%rbp
5d pop %rbp
c3 retq
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
This patch fixes this via s/inline/__always_inline/
To avoid touching 32-bit case where such change was not tested
to be a win, reformat __arch_hweight64() to have completely
disjoint 64-bit and 32-bit implementations. IOW: made #ifdef /
32 bits and 64 bits instead of having #ifdef / #else / #endif
inside a single function body. Only 64-bit __arch_hweight64() is
__always_inline'd.
text data bss dec filename
86971120 17195912 36659200 140826232 vmlinux.before
86970954 17195912 36659200 140826066 vmlinux
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1438697716-28121-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/arch_hweight.h | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/arch/x86/include/asm/arch_hweight.h b/arch/x86/include/asm/arch_hweight.h index 9686c3d9ff73..259a7c1ef709 100644 --- a/arch/x86/include/asm/arch_hweight.h +++ b/arch/x86/include/asm/arch_hweight.h @@ -21,7 +21,7 @@ * ARCH_HWEIGHT_CFLAGS in <arch/x86/Kconfig> for the respective * compiler switches. */ -static inline unsigned int __arch_hweight32(unsigned int w) +static __always_inline unsigned int __arch_hweight32(unsigned int w) { unsigned int res = 0; @@ -42,20 +42,23 @@ static inline unsigned int __arch_hweight8(unsigned int w) return __arch_hweight32(w & 0xff); } +#ifdef CONFIG_X86_32 static inline unsigned long __arch_hweight64(__u64 w) { - unsigned long res = 0; - -#ifdef CONFIG_X86_32 return __arch_hweight32((u32)w) + __arch_hweight32((u32)(w >> 32)); +} #else +static __always_inline unsigned long __arch_hweight64(__u64 w) +{ + unsigned long res = 0; + asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT) : "="REG_OUT (res) : REG_IN (w)); -#endif /* CONFIG_X86_32 */ return res; } +#endif /* CONFIG_X86_32 */ #endif |