> -----Original Message----- > From: Nathan Chancellor <nathan@xxxxxxxxxx> > Sent: Tuesday, December 17, 2024 11:44 AM > To: Brian Cain <bcain@xxxxxxxxxxx>; Andrew Morton <akpm@linux- > foundation.org>; Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Cc: linux-hexagon@xxxxxxxxxxxxxxx; patches@xxxxxxxxxxxxxxx; > llvm@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2] hexagon: Disable constant extender optimization for > LLVM prior to 19.1.0 > > > Hi Linus, > > Could you apply this change [1] directly? Brian has reviewed it and I have > sent this patch twice plus another ping for application [2]. I would > like to stop applying this in our CI and some other people have hit it > as well. Nathan, I'm sorry. You should not have to send these changes to Linus. I should have carried it in my tree and proposed it to Linus. I'll do that, if you don't mind. > [1]: https://lore.kernel.org/all/20241121-hexagon-disable-constant- > expander-pass-v2-1-1a92e9afb0f4@xxxxxxxxxx/ > [2]: https://lore.kernel.org/all/20241001185848.GA562711@thelio-3990X/ > > Cheers, > Nathan > > On Thu, Nov 21, 2024 at 11:22:18AM -0700, Nathan Chancellor wrote: > > The Hexagon-specific constant extender optimization in LLVM may crash on > > Linux kernel code [1], such as fs/bcache/btree_io.c after > > commit 32ed4a620c54 ("bcachefs: Btree path tracepoints") in 6.12: > > > > clang: llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp:745: bool > (anonymous namespace)::HexagonConstExtenders::ExtRoot::operator<(const > HCE::ExtRoot &) const: Assertion `ThisB->getParent() == OtherB->getParent()' > failed. > > Stack dump: > > 0. Program arguments: clang --target=hexagon-linux-musl ... > fs/bcachefs/btree_io.c > > 1. <eof> parser at end of file > > 2. Code generation > > 3. Running pass 'Function Pass Manager' on module > 'fs/bcachefs/btree_io.c'. > > 4. Running pass 'Hexagon constant-extender optimization' on function > '@__btree_node_lock_nopath' > > > > Without assertions enabled, there is just a hang during compilation. > > > > This has been resolved in LLVM main (20.0.0) [2] and backported to LLVM > > 19.1.0 but the kernel supports LLVM 13.0.1 and newer, so disable the > > constant expander optimization using the '-mllvm' option when using a > > toolchain that is not fixed. > > > > Cc: stable@xxxxxxxxxxxxxxx > > Link: https://github.com/llvm/llvm-project/issues/99714 [1] > > Link: https://github.com/llvm/llvm- > project/commit/68df06a0b2998765cb0a41353fcf0919bbf57ddb [2] > > Link: https://github.com/llvm/llvm- > project/commit/2ab8d93061581edad3501561722ebd5632d73892 [3] > > Reviewed-by: Brian Cain <bcain@xxxxxxxxxxx> > > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > --- > > Andrew, can you please take this for 6.13? Our CI continues to hit this. > > > > Changes in v2: > > - Rebase on 6.12 to make sure it is still applicable > > - Name exact bcachefs commit that introduces crash now that it is > > merged > > - Add 'Cc: stable' as this is now visible in a stable release > > - Carry forward Brian's reviewed-by > > - Link to v1: https://lore.kernel.org/r/20240819-hexagon-disable-constant- > expander-pass-v1-1-36a734e9527d@xxxxxxxxxx > > --- > > arch/hexagon/Makefile | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile > > index > 92d005958dfb232d48a4ca843b46262a84a08eb4..ff172cbe5881a074f9d94 > 30c37071992a4c8beac 100644 > > --- a/arch/hexagon/Makefile > > +++ b/arch/hexagon/Makefile > > @@ -32,3 +32,9 @@ KBUILD_LDFLAGS += $(ldflags-y) > > TIR_NAME := r19 > > KBUILD_CFLAGS += -ffixed-$(TIR_NAME) - > DTHREADINFO_REG=$(TIR_NAME) -D__linux__ > > KBUILD_AFLAGS += -DTHREADINFO_REG=$(TIR_NAME) > > + > > +# Disable HexagonConstExtenders pass for LLVM versions prior to 19.1.0 > > +# https://github.com/llvm/llvm-project/issues/99714 > > +ifneq ($(call clang-min-version, 190100),y) > > +KBUILD_CFLAGS += -mllvm -hexagon-cext=false > > +endif > > > > --- > > base-commit: adc218676eef25575469234709c2d87185ca223a > > change-id: 20240802-hexagon-disable-constant-expander-pass- > 8b6b61db6afc > > > > Best regards, > > -- > > Nathan Chancellor <nathan@xxxxxxxxxx> > >
