* [PATCH] hexagon: Disable constant extender optimization for LLVM prior to 19.1.0
@ 2024-08-19 18:16 Nathan Chancellor
2024-10-01 18:58 ` Nathan Chancellor
0 siblings, 1 reply; 3+ messages in thread
From: Nathan Chancellor @ 2024-08-19 18:16 UTC (permalink / raw)
To: Brian Cain, Andrew Morton; +Cc: linux-hexagon, patches, llvm, Nathan Chancellor
The Hexagon-specific constant extender optimization in LLVM may crash on
Linux kernel code [1] (such as with a bcachefs change in -next):
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.
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]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
arch/hexagon/Makefile | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile
index 92d005958dfb..ff172cbe5881 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: 47ac09b91befbb6a235ab620c32af719f8208399
change-id: 20240802-hexagon-disable-constant-expander-pass-8b6b61db6afc
Best regards,
--
Nathan Chancellor <nathan@kernel.org>
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] hexagon: Disable constant extender optimization for LLVM prior to 19.1.0
2024-08-19 18:16 [PATCH] hexagon: Disable constant extender optimization for LLVM prior to 19.1.0 Nathan Chancellor
@ 2024-10-01 18:58 ` Nathan Chancellor
2024-10-01 19:08 ` Brian Cain
0 siblings, 1 reply; 3+ messages in thread
From: Nathan Chancellor @ 2024-10-01 18:58 UTC (permalink / raw)
To: Brian Cain, Andrew Morton; +Cc: linux-hexagon, patches, llvm
Ping? This hang is now happening in 6.12-rc1 in our CI.
On Mon, Aug 19, 2024 at 11:16:10AM -0700, Nathan Chancellor wrote:
> The Hexagon-specific constant extender optimization in LLVM may crash on
> Linux kernel code [1] (such as with a bcachefs change in -next):
>
> 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.
>
> 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]
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> arch/hexagon/Makefile | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile
> index 92d005958dfb..ff172cbe5881 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: 47ac09b91befbb6a235ab620c32af719f8208399
> change-id: 20240802-hexagon-disable-constant-expander-pass-8b6b61db6afc
>
> Best regards,
> --
> Nathan Chancellor <nathan@kernel.org>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: [PATCH] hexagon: Disable constant extender optimization for LLVM prior to 19.1.0
2024-10-01 18:58 ` Nathan Chancellor
@ 2024-10-01 19:08 ` Brian Cain
0 siblings, 0 replies; 3+ messages in thread
From: Brian Cain @ 2024-10-01 19:08 UTC (permalink / raw)
To: Nathan Chancellor, Andrew Morton
Cc: linux-hexagon@vger.kernel.org, patches@lists.linux.dev,
llvm@lists.linux.dev
> -----Original Message-----
> From: Nathan Chancellor <nathan@kernel.org>
> Sent: Tuesday, October 1, 2024 1:59 PM
> To: Brian Cain <bcain@quicinc.com>; Andrew Morton <akpm@linux-
> foundation.org>
> Cc: linux-hexagon@vger.kernel.org; patches@lists.linux.dev;
> llvm@lists.linux.dev
> Subject: Re: [PATCH] hexagon: Disable constant extender optimization for LLVM
> prior to 19.1.0
>
> WARNING: This email originated from outside of Qualcomm. Please be wary of
> any links or attachments, and do not enable macros.
>
> Ping? This hang is now happening in 6.12-rc1 in our CI.
>
> On Mon, Aug 19, 2024 at 11:16:10AM -0700, Nathan Chancellor wrote:
> > The Hexagon-specific constant extender optimization in LLVM may crash on
> > Linux kernel code [1] (such as with a bcachefs change in -next):
> >
> > 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.
> >
> > 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]
> > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> > ---
Reviewed-by: Brian Cain <bcain@quicinc.com>
> > arch/hexagon/Makefile | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile
> > index 92d005958dfb..ff172cbe5881 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: 47ac09b91befbb6a235ab620c32af719f8208399
> > change-id: 20240802-hexagon-disable-constant-expander-pass-8b6b61db6afc
> >
> > Best regards,
> > --
> > Nathan Chancellor <nathan@kernel.org>
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-08-19 18:16 [PATCH] hexagon: Disable constant extender optimization for LLVM prior to 19.1.0 Nathan Chancellor
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