Re: [PATCH v2 2/7] Revert "kbuild: disable clang's default use of -fmerge-all-constants"
On Tue, Sep 1, 2020 at 2:23 AM Nick Desaulniers wrote: > > This reverts commit 87e0d4f0f37fb0c8c4aeeac46fff5e957738df79. > > This was fixed in clang-6; the minimum supported version of clang in the > kernel is clang-10 (10.0.1). > > Link: https://reviews.llvm.org/rL329300. > Link: https://github.com/ClangBuiltLinux/linux/issues/9 > Suggested-by: Nathan Chancellor > Signed-off-by: Nick Desaulniers Reviewed-by: Sedat Dilek Tested-by: Sedat Dilek - Sedat - > --- > Makefile | 9 - > 1 file changed, 9 deletions(-) > > diff --git a/Makefile b/Makefile > index 37739ee53f27..144ac6a073ff 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 >
Re: [PATCH v2 2/7] Revert "kbuild: disable clang's default use of -fmerge-all-constants"
On 2020-08-31, Nathan Chancellor wrote: On Mon, Aug 31, 2020 at 05:23:21PM -0700, Nick Desaulniers wrote: This reverts commit 87e0d4f0f37fb0c8c4aeeac46fff5e957738df79. This was fixed in clang-6; the minimum supported version of clang in the kernel is clang-10 (10.0.1). Link: https://reviews.llvm.org/rL329300. Link: https://github.com/ClangBuiltLinux/linux/issues/9 Suggested-by: Nathan Chancellor Signed-off-by: Nick Desaulniers Reviewed-by: Nathan Chancellor How about expanding "This was fixed in clang-6" to be -fno-merge-all-constants has been the default since clang-6? (Both gcc|clang -fmerge-all-constants can cause an assertion failure for the example on https://bugs.llvm.org/show_bug.cgi?id=18538 ) Reviewed-by: Fangrui Song --- Makefile | 9 - 1 file changed, 9 deletions(-) diff --git a/Makefile b/Makefile index 37739ee53f27..144ac6a073ff 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 -- You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20200901045516.GA1561318%40ubuntu-n2-xlarge-x86.
Re: [PATCH v2 2/7] Revert "kbuild: disable clang's default use of -fmerge-all-constants"
On Mon, Aug 31, 2020 at 05:23:21PM -0700, Nick Desaulniers wrote: > This reverts commit 87e0d4f0f37fb0c8c4aeeac46fff5e957738df79. > > This was fixed in clang-6; the minimum supported version of clang in the > kernel is clang-10 (10.0.1). > > Link: https://reviews.llvm.org/rL329300. > Link: https://github.com/ClangBuiltLinux/linux/issues/9 > Suggested-by: Nathan Chancellor > Signed-off-by: Nick Desaulniers Reviewed-by: Nathan Chancellor > --- > Makefile | 9 - > 1 file changed, 9 deletions(-) > > diff --git a/Makefile b/Makefile > index 37739ee53f27..144ac6a073ff 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 >
[PATCH v2 2/7] Revert "kbuild: disable clang's default use of -fmerge-all-constants"
This reverts commit 87e0d4f0f37fb0c8c4aeeac46fff5e957738df79. This was fixed in clang-6; the minimum supported version of clang in the kernel is clang-10 (10.0.1). Link: https://reviews.llvm.org/rL329300. Link: https://github.com/ClangBuiltLinux/linux/issues/9 Suggested-by: Nathan Chancellor Signed-off-by: Nick Desaulniers --- Makefile | 9 - 1 file changed, 9 deletions(-) diff --git a/Makefile b/Makefile index 37739ee53f27..144ac6a073ff 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
