Commit-ID: d14edb1648221e59fc9fd47127fcc57bf26d759f
Gitweb: http://git.kernel.org/tip/d14edb1648221e59fc9fd47127fcc57bf26d759f
Author: Denys Vlasenko <[email protected]>
AuthorDate: Tue, 4 Aug 2015 16:15:15 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 5 Aug 2015 09:38:09 +0200
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 <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Thomas Graf <[email protected]>
Cc: [email protected]
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/include/asm/arch_hweight.h | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/arch_hweight.h
b/arch/x86/include/asm/arch_hweight.h
index 9686c3d..259a7c1 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
--
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