fs/btrfs/relocation.o: warning: objtool: update_backref_cache()+0xf8: unreachable instruction

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   fc3abb53250a90ba2150eebd182137c136f4d25a
commit: e9a28dc52af31d8af1883afe08e724a303b3c4eb btrfs: rename tree_entry to rb_simple_node and export it
date:   3 months ago
config: x86_64-randconfig-a006-20200903 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        git checkout e9a28dc52af31d8af1883afe08e724a303b3c4eb
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> fs/btrfs/relocation.o: warning: objtool: update_backref_cache()+0xf8: unreachable instruction

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https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
Description: application/gzip