arch/mips/boot/compressed/bswapsi.c:5:22: warning: no previous prototype for '__bswapsi2'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   de5540965853e514a85d3b775e9049deb85a2ff3
commit: cddc40f5617e53f97ef019d5b29c1bd6cbb031ec mips: always link byteswap helpers into decompressor
date:   6 days ago
config: mips-randconfig-r005-20210711 (attached as .config)
compiler: mips64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cddc40f5617e53f97ef019d5b29c1bd6cbb031ec
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout cddc40f5617e53f97ef019d5b29c1bd6cbb031ec
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 

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

All warnings (new ones prefixed by >>):

>> arch/mips/boot/compressed/bswapsi.c:5:22: warning: no previous prototype for '__bswapsi2' [-Wmissing-prototypes]
       5 | unsigned int notrace __bswapsi2(unsigned int u)
         |                      ^~~~~~~~~~

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
Description: application/gzip