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aef25be35d
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@vger.kernel.org
Link: https://github.com/llvm/llvm-project/issues/99714 [1]
Link: 68df06a0b2 [2]
Link: 2ab8d93061 [3]
Reviewed-by: Brian Cain <bcain@quicinc.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
41 lines
1.3 KiB
Makefile
41 lines
1.3 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# Makefile for the Hexagon arch
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KBUILD_DEFCONFIG = comet_defconfig
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# Do not use GP-relative jumps
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KBUILD_CFLAGS += -G0
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LDFLAGS_vmlinux += -G0
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# Do not use single-byte enums; these will overflow.
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KBUILD_CFLAGS += -fno-short-enums
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# We must use long-calls:
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KBUILD_CFLAGS += -mlong-calls
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# Modules must use either long-calls, or use pic/plt.
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# Use long-calls for now, it's easier. And faster.
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# KBUILD_CFLAGS_MODULE += -fPIC
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# KBUILD_LDFLAGS_MODULE += -shared
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KBUILD_CFLAGS_MODULE += -mlong-calls
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cflags-y += $(call cc-option,-mv${CONFIG_HEXAGON_ARCH_VERSION})
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aflags-y += $(call cc-option,-mv${CONFIG_HEXAGON_ARCH_VERSION})
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ldflags-y += $(call cc-option,-mv${CONFIG_HEXAGON_ARCH_VERSION})
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KBUILD_CFLAGS += $(cflags-y)
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KBUILD_AFLAGS += $(aflags-y)
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KBUILD_LDFLAGS += $(ldflags-y)
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# Thread-info register will be r19. This value is not configureable;
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# it is hard-coded in several files.
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TIR_NAME := r19
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KBUILD_CFLAGS += -ffixed-$(TIR_NAME) -DTHREADINFO_REG=$(TIR_NAME) -D__linux__
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KBUILD_AFLAGS += -DTHREADINFO_REG=$(TIR_NAME)
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# Disable HexagonConstExtenders pass for LLVM versions prior to 19.1.0
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# https://github.com/llvm/llvm-project/issues/99714
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ifneq ($(call clang-min-version, 190100),y)
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KBUILD_CFLAGS += -mllvm -hexagon-cext=false
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endif
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