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 / #else / #endif blocks contain complete function definitions for 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 hex filename 86971120 17195912 36659200 140826232 864d678 vmlinux.before 86970954 17195912 36659200 140826066 864d5d2 vmlinux Signed-off-by: Denys Vlasenko <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Thomas Graf <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: David Rientjes <[email protected]> Cc: Andrew Morton <[email protected]> Cc: [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 -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
