Hi Bill, I love your patch! Perhaps something to improve: [auto build test WARNING on linus/master] [also build test WARNING on v5.11-rc3] [cannot apply to powerpc/next s390/features tip/x86/core next-20210111] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Bill-Wendling/pgo-add-clang-s-Profile-Guided-Optimization-infrastructure/20210112-133315 base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a0d54b4f5b219fb31f0776e9f53aa137e78ae431 config: x86_64-allyesconfig (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/6ab85bae7667afd0aa68c6442b7ca5c369fa1088 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Bill-Wendling/pgo-add-clang-s-Profile-Guided-Optimization-infrastructure/20210112-133315 git checkout 6ab85bae7667afd0aa68c6442b7ca5c369fa1088 # 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 All warnings (new ones prefixed by >>): kernel/pgo/instrument.c:72:6: warning: no previous prototype for '__llvm_profile_instrument_target' [-Wmissing-prototypes] 72 | void __llvm_profile_instrument_target(u64 target_value, void *data, u32 index) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/pgo/instrument.c:135:6: warning: no previous prototype for '__llvm_profile_instrument_range' [-Wmissing-prototypes] 135 | void __llvm_profile_instrument_range(u64 target_value, void *data, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> kernel/pgo/instrument.c:179:6: warning: no previous prototype for '__llvm_profile_instrument_memop' [-Wmissing-prototypes] 179 | void __llvm_profile_instrument_memop(u64 target_value, void *data, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ vim +/__llvm_profile_instrument_memop +179 kernel/pgo/instrument.c 174 175 /* 176 * The target values are partitioned into multiple ranges. The range spec is 177 * defined in compiler-rt/include/profile/InstrProfData.inc. 178 */ > 179 void __llvm_profile_instrument_memop(u64 target_value, void *data, --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org