| Message ID | 20221228-drop-qunused-arguments-v1-0-658cbc8fc592@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Remove clang's -Qunused-arguments from KBUILD_CPPFLAGS | expand |
On Wed, Jan 04, 2023 at 12:54:18PM -0700, Nathan Chancellor wrote: > Hi all, ... > This series has seen my personal test framework, which tests several different > configurations and architectures, with LLVM tip of tree (16.0.0). I have done > defconfig, allmodconfig, and allnoconfig builds for arm, arm64, i386, mips, > powerpc, riscv, s390, and x86_64 with GCC 12.2.0 as well but I am hoping the > rest of the test infrastructure will catch any lurking problems. > > I would like this series to stay together so that there is no opportunity for > breakage so please consider giving acks so that this can be carried via the > kbuild tree. ... > s390/vdso: Drop unused '-s' flag from KBUILD_AFLAGS_64 > s390/vdso: Drop '-shared' from KBUILD_CFLAGS_64 > s390/purgatory: Remove unused '-MD' and unnecessary '-c' flags ... > arch/s390/kernel/vdso64/Makefile | 4 +-- > arch/s390/purgatory/Makefile | 2 +- For the s390 bits: Acked-by: Heiko Carstens <hca@linux.ibm.com>
Hi all, Clang can emit a few different warnings when it encounters a flag that it recognizes but does not support internally. These warnings are elevated to errors within {as,cc}-option via -Werror to catch unsupported flags that should not be added to KBUILD_{A,C}FLAGS; see commit c3f0d0bc5b01 ("kbuild, LLVMLinux: Add -Werror to cc-option to support clang"). If an unsupported flag is unconditionally to KBUILD_{A,C}FLAGS, all subsequent {as,cc}-option will always fail, preventing supported and even potentially necessary flags from getting adding to the tool flags. One would expect these warnings to be visible in the kernel build logs since they are added to KBUILD_{A,C}FLAGS but unfortunately, these warnings are hidden with clang's -Qunused-arguments flag, which is added to KBUILD_CPPFLAGS and used for both compiling and assembling files. Patches 1-4 address the internal inconsistencies of invoking the assembler within kbuild by using KBUILD_AFLAGS consistently and using '-x assembler-with-cpp' over '-x assembler'. This matches how assembly files are built across the kernel and helps avoid problems in situations where macro definitions or warning flags are present in KBUILD_AFLAGS, which cause instances of -Wunused-command-line-argument when the preprocessor is not called to consume them. There were a couple of places in architecture code where this change would break things so those are fixed first. Patches 5-12 clean up warnings that will show up when -Qunused-argument is dropped. I hope none of these are controversial. Patch 13 turns two warnings into errors so that the presence of unused flags cannot be easily ignored. Patch 14 drops -Qunused-argument. This is done last so that it can be easily reverted if need be. This series has seen my personal test framework, which tests several different configurations and architectures, with LLVM tip of tree (16.0.0). I have done defconfig, allmodconfig, and allnoconfig builds for arm, arm64, i386, mips, powerpc, riscv, s390, and x86_64 with GCC 12.2.0 as well but I am hoping the rest of the test infrastructure will catch any lurking problems. I would like this series to stay together so that there is no opportunity for breakage so please consider giving acks so that this can be carried via the kbuild tree. --- Nathan Chancellor (12): MIPS: Always use -Wa,-msoft-float and eliminate GAS_HAS_SET_HARDFLOAT MIPS: Prefer cc-option for additions to cflags powerpc: Remove linker flag from KBUILD_AFLAGS powerpc/vdso: Remove unused '-s' flag from ASFLAGS powerpc/vdso: Improve linker flags powerpc/vdso: Remove an unsupported flag from vgettimeofday-32.o with clang s390/vdso: Drop unused '-s' flag from KBUILD_AFLAGS_64 s390/vdso: Drop '-shared' from KBUILD_CFLAGS_64 s390/purgatory: Remove unused '-MD' and unnecessary '-c' flags drm/amd/display: Do not add '-mhard-float' to dml_ccflags for clang kbuild: Turn a couple more of clang's unused option warnings into errors kbuild: Stop using '-Qunused-arguments' with clang Nick Desaulniers (2): x86/boot/compressed: prefer cc-option for CFLAGS additions kbuild: Update assembler calls to use proper flags and language target Makefile | 1 - arch/mips/Makefile | 13 ++------- arch/mips/include/asm/asmmacro-32.h | 4 +-- arch/mips/include/asm/asmmacro.h | 42 ++++++++++++++--------------- arch/mips/include/asm/fpregdef.h | 14 ---------- arch/mips/include/asm/mipsregs.h | 20 +++----------- arch/mips/kernel/genex.S | 2 +- arch/mips/kernel/r2300_fpu.S | 4 +-- arch/mips/kernel/r4k_fpu.S | 12 ++++----- arch/mips/kvm/fpu.S | 6 ++--- arch/mips/loongson2ef/Platform | 2 +- arch/powerpc/Makefile | 2 +- arch/powerpc/kernel/vdso/Makefile | 25 +++++++++++------ arch/s390/kernel/vdso64/Makefile | 4 +-- arch/s390/purgatory/Makefile | 2 +- arch/x86/boot/compressed/Makefile | 2 +- drivers/gpu/drm/amd/display/dc/dml/Makefile | 3 ++- scripts/Kconfig.include | 2 +- scripts/Makefile.clang | 2 ++ scripts/Makefile.compiler | 8 +++--- scripts/as-version.sh | 2 +- 21 files changed, 74 insertions(+), 98 deletions(-) --- base-commit: 88603b6dc419445847923fcb7fe5080067a30f98 change-id: 20221228-drop-qunused-arguments-0c5c7dae54fb Best regards,