Messages in this thread Patch in this message | | | Date | Wed, 2 Sep 2020 15:59:06 -0700 | Subject | [PATCH v3 2/7] Revert "kbuild: disable clang's default use of -fmerge-all-constants" | From | Nick Desaulniers <> |
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This reverts commit 87e0d4f0f37fb0c8c4aeeac46fff5e957738df79.
-fno-merge-all-constants has been the default since clang-6; the minimum supported version of clang in the kernel is clang-10 (10.0.1).
Suggested-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Reviewed-by: Fangrui Song <maskray@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://reviews.llvm.org/rL329300. Link: https://github.com/ClangBuiltLinux/linux/issues/9 --- Makefile | 9 --------- 1 file changed, 9 deletions(-)
diff --git a/Makefile b/Makefile index 1cfa5029fd2f..e475650c9599 100644 --- a/Makefile +++ b/Makefile @@ -932,15 +932,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning, maybe-uninitialized) # disable invalid "can't wrap" optimizations for signed / pointers KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow) -# clang sets -fmerge-all-constants by default as optimization, but this -# is non-conforming behavior for C and in fact breaks the kernel, so we -# need to disable it here generally. -KBUILD_CFLAGS += $(call cc-option,-fno-merge-all-constants) - -# for gcc -fno-merge-all-constants disables everything, but it is fine -# to have actual conforming behavior enabled. -KBUILD_CFLAGS += $(call cc-option,-fmerge-constants) - # Make sure -fstack-check isn't enabled (like gentoo apparently did) KBUILD_CFLAGS += $(call cc-option,-fno-stack-check,) -- 2.28.0.402.g5ffc5be6b7-goog
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