https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122
--- Comment #6 from Denis Vlasenko <vda.linux at googlemail dot com> --- Got a hold on a machine with gcc version 5.1.1 20150422 (Red Hat 5.1.1-1) Pulled current Linus kernel tree and built it with this config: http://busybox.net/~vda/kernel_config2 Note that "CONFIG_CC_OPTIMIZE_FOR_SIZE is not set", i.e. it's a -O2 build. Selecting duplicate functions still shows a number of tiny uninlined functions: $ nm --size-sort vmlinux | grep -iF ' t ' | uniq -c | grep -v '^ *1 ' | sort -rn 83 000000000000008a t rcu_read_lock_sched_held 48 000000000000001b t sd_driver_init 48 0000000000000012 t sd_driver_exit 48 0000000000000008 t __initcall_sd_driver_init6 47 0000000000000020 t usb_serial_module_init 47 0000000000000012 t usb_serial_module_exit 47 0000000000000008 t __initcall_usb_serial_module_init6 45 0000000000000057 t uni2char 45 0000000000000025 t char2uni 43 000000000000001f t sd_probe 40 000000000000006a t rcu_read_unlock 29 000000000000005a t cpumask_next 27 000000000000007a t rcu_read_lock 27 0000000000000011 t kzalloc 24 0000000000000022 t arch_local_save_flags 23 0000000000000041 t cpumask_check 19 0000000000000017 t phy_module_init 19 0000000000000017 t phy_module_exit 19 0000000000000008 t __initcall_phy_module_init6 18 000000000000006c t spi_write 18 000000000000003f t show_alarm 18 000000000000000b t bitmap_weight 15 0000000000000037 t show_alarms 15 0000000000000014 t init_once 14 0000000000000603 t init_engine 14 0000000000000354 t pcm_trigger 14 000000000000033b t pcm_open 14 00000000000000f8 t stop_transport 14 00000000000000db t pcm_close 14 00000000000000c8 t set_meters_on 14 00000000000000b5 t write_dsp 14 00000000000000b5 t pcm_hw_free 14 0000000000000091 t pcm_pointer 14 0000000000000090 t hw_rule_playback_channels_by_format 14 000000000000008d t send_vector 14 000000000000004f t snd_echo_vumeters_info 14 0000000000000042 t hw_rule_sample_rate 14 000000000000003e t snd_echo_vumeters_switch_put 14 0000000000000034 t audiopipe_free 14 000000000000002b t snd_echo_channels_info_info 14 0000000000000024 t snd_echo_remove 14 000000000000001b t echo_driver_init 14 0000000000000019 t pcm_analog_out_hw_params 14 0000000000000019 t arch_local_irq_restore 14 0000000000000014 t snd_echo_dev_free 14 0000000000000012 t echo_driver_exit 14 0000000000000008 t __initcall_echo_driver_init6 13 0000000000000127 t pcm_analog_out_open 13 0000000000000127 t pcm_analog_in_open 13 0000000000000039 t qdisc_peek_dequeued 13 0000000000000037 t cpumask_check 13 0000000000000022 t arch_local_irq_restore 13 000000000000001c t pcm_analog_in_hw_params 13 0000000000000006 t bcma_host_soc_unregister_driver 12 0000000000000053 t nlmsg_trim ... Such as: ffffffff811a42e0 <kzalloc>: ffffffff811a42e0: 55 push %rbp ffffffff811a42e1: 81 ce 00 80 00 00 or $0x8000,%esi ffffffff811a42e7: 48 89 e5 mov %rsp,%rbp ffffffff811a42ea: e8 f1 92 1a 00 callq <__kmalloc> ffffffff811a42ef: 5d pop %rbp ffffffff811a42f0: c3 retq ffffffff810792d0 <bitmap_weight>: ffffffff810792d0: 55 push %rbp ffffffff810792d1: 48 89 e5 mov %rsp,%rbp ffffffff810792d4: e8 37 a8 b7 00 callq <__bitmap_weight> ffffffff810792d9: 5d pop %rbp ffffffff810792da: c3 retq and even ffffffff88566c9b <bcma_host_soc_unregister_driver>: ffffffff88566c9b: 55 push %rbp ffffffff88566c9c: 48 89 e5 mov %rsp,%rbp ffffffff88566c9f: 5d pop %rbp ffffffff88566ca0: c3 retq This is an *empty function* from drivers/bcma/bcma_private.h:103 uninlined: static inline void __exit bcma_host_soc_unregister_driver(void) { } BTW it doesn't even have any callers in vmlinux. It should have been optimized out.
