`./python -m test test_interpreters test_struct` fails with: KeyError: concurrent.interpreters._queues.UNBOUND

[ppigazzini]

Bug report

Bug description:

I routinely use on my Ubuntu machines pyenv and a script to install python versions:

Click to view

 python_ver=3.14.2

# setup pyenv and install latest python
# https://github.com/pyenv/pyenv
# https://github.com/python/pyperformance

if ! command -v pyenv &>/dev/null; then
 # dependencies according to pyenv
 #sudo apt update; sudo apt install -y build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev

 # Workaround missing libmpdec-dev on ubuntu 24.04 (it should be re introduced in ubuntu 26.04):
 # https://launchpad.net/~ondrej/+archive/ubuntu/php
 # https://deb.sury.org/
 sudo add-apt-repository -y ppa:ondrej/php

 # dependencies according to python build doc dropping packages used in CI (ccache, cmake, gdb, inetutils-inetd, lcov, lzma, strace, xvfb)
 # https://devguide.python.org/getting-started/setup-building/index.html#build-dependencies
 # https://github.com/python/cpython/blob/main/.github/workflows/posix-deps-apt.sh
 sudo apt update; sudo apt install -y build-essential pkg-config libb2-dev libbz2-dev libffi-dev libgdbm-dev libgdbm-compat-dev liblzma-dev libncurses5-dev libreadline6-dev libsqlite3-dev libssl-dev lzma-dev tk-dev uuid-dev zlib1g-dev libzstd-dev libmpdec-dev

 pyenv_dir="$HOME/.pyenv"
 git clone https://github.com/pyenv/pyenv.git "$pyenv_dir"

 cat << 'EOF' >> "$HOME/.profile"

# pyenv: keep at the end of the file
export PYENV_ROOT="$HOME/.pyenv"
command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -)"
EOF

 cat << 'EOF' >> "$HOME/.bashrc"

# pyenv: keep at the end of the file
export PYENV_ROOT="$HOME/.pyenv"
command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -)"
EOF

 . "$HOME/.profile"
 pushd "$pyenv_dir" && src/configure && make -C src && popd
 #CC="clang" CXX="clang++" LDFLAGS="${LDFLAGS:+$LDFLAGS }-fuse-ld=lld" PYTHON_CONFIGURE_OPTS="--enable-optimizations --with-lto --with-tail-call-interp --enable-bolt" PYTHON_CFLAGS="-march=native -mtune=native" pyenv install "$python_ver"
 CC="clang" CXX="clang++" LDFLAGS="${LDFLAGS:+$LDFLAGS }-fuse-ld=lld" PYTHON_CONFIGURE_OPTS="--enable-optimizations --with-lto" PYTHON_CFLAGS="-march=native -mtune=native" pyenv install "$python_ver"
 #PYTHON_CONFIGURE_OPTS="--enable-optimizations --with-lto" PYTHON_CFLAGS="-march=native -mtune=native" pyenv install "$python_ver"
 pyenv global "$python_ver"
fi

test_struct fails in python3 -m test with python 3.14.2 (and 3.14.1) with this traceback:

Click to view

0:18:03 load avg: 0.84 [387/491] test_struct
Exception in initializer:
Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
test test_struct failed -- Traceback (most recent call last):
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/test/test_struct.py", line 818, in test_endian_table_init_subinterpreters
 self.assertListEqual(list(results), [None] * 5)
 ~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 639, in result_iterator
 yield _result_or_cancel(fs.pop())
 ~~~~~~~~~~~~~~~~~^^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 311, in _result_or_cancel
 return fut.result(timeout)
 ~~~~~~~~~~^^^^^^^^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 450, in result
 return self.__get_result()
 ~~~~~~~~~~~~~~~~~^^
 File "/home/usr00/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 395, in __get_result
 raise self._exception
concurrent.futures.interpreter.BrokenInterpreterPool: A thread initializer failed, the thread pool is not usable anymore

0:18:04 load avg: 0.84 [387/491/1] test_struct failed (1 error)

Tested on Ubuntu 24.04 (gcc 14.2.0 - clang 21.1.8) and Ubuntu 20.04 (gcc 11.4.0), several CPUs.

python 3.14.0 and 3.13.x, bult in the same way, pass smoothly python3 -m test

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-142414: Unify UNBOUND in Lib/concurrent/interpreters/_queues.py and Lib/concurrent/interpreters/_crossinterp.py. #142515
• gh-142414: Remove singleton design pattern in _crossinterp.py #142553
• gh-142414: Remove singleton design pattern in Lib/concurrent/interpreters/_crossinterp.py. #142577
• gh-142414: Isolate reloading modules in test_interpreters #144096
• gh-142414: Make value, not identity, matter for UNBOUND* objects #145184

[thesamesam]

Given your use of -march=native, I think you need to share what it resolves to.

[ppigazzini]

All these 5 machines have python 3.14.0, at least one version of python 3.13.7 - 3.13.9 - 3.13.11, one machine has 3.6.15 as well. python3 -m test had problems with 3.14.1 (even segmentation fault with clang on 2 machines) and with 3.14.2 test_struct fails for any compiler/CPU.

Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz - Ubuntu 24.04

clang -E - -march=native -###

Ubuntu clang version 21.1.8 (++20251202083326+f68f64eb8130-1~exp1~20251202083450.66)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-21/bin
 (in-process)
 "/usr/lib/llvm-21/bin/clang" "-cc1" "-triple" "x86_64-pc-linux-gnu" "-E" "-disable-free" "-clear-ast-before-backend" "-disable-llvm-verifier" "-discard-value-names" "-main-file-name" "-" "-mrelocation-model" "pic" "-pic-level" "2" "-pic-is-pie" "-mframe-pointer=all" "-fmath-errno" "-ffp-contract=on" "-fno-rounding-math" "-mconstructor-aliases" "-funwind-tables=2" "-target-cpu" "haswell" "-target-feature" "-prfchw" "-target-feature" "-cldemote" "-target-feature" "+avx" "-target-feature" "+aes" "-target-feature" "+sahf" "-target-feature" "+pclmul" "-target-feature" "-xop" "-target-feature" "+crc32" "-target-feature" "-amx-fp8" "-target-feature" "-xsaves" "-target-feature" "-avx512fp16" "-target-feature" "-usermsr" "-target-feature" "-sm4" "-target-feature" "-egpr" "-target-feature" "+sse4.1" "-target-feature" "-avx512ifma" "-target-feature" "+xsave" "-target-feature" "+sse4.2" "-target-feature" "-tsxldtrk" "-target-feature" "-sm3" "-target-feature" "-ptwrite" "-target-feature" "-widekl" "-target-feature" "-movrs" "-target-feature" "+invpcid" "-target-feature" "+64bit" "-target-feature" "-xsavec" "-target-feature" "-avx10.1-512" "-target-feature" "-avx512vpopcntdq" "-target-feature" "+cmov" "-target-feature" "-avx512vp2intersect" "-target-feature" "-avx512cd" "-target-feature" "+movbe" "-target-feature" "-avxvnniint8" "-target-feature" "-ccmp" "-target-feature" "-amx-int8" "-target-feature" "-kl" "-target-feature" "-avx10.1-256" "-target-feature" "-sha512" "-target-feature" "-avxvnni" "-target-feature" "-rtm" "-target-feature" "-adx" "-target-feature" "+avx2" "-target-feature" "-hreset" "-target-feature" "-movdiri" "-target-feature" "-serialize" "-target-feature" "-vpclmulqdq" "-target-feature" "-avx512vl" "-target-feature" "-uintr" "-target-feature" "-cf" "-target-feature" "-clflushopt" "-target-feature" "-raoint" "-target-feature" "-cmpccxadd" "-target-feature" "+bmi" "-target-feature" "-amx-tile" "-target-feature" "+sse" "-target-feature" "-avx10.2-256" "-target-feature" "-gfni" "-target-feature" "-avxvnniint16" "-target-feature" "-amx-fp16" "-target-feature" "-zu" "-target-feature" "-ndd" "-target-feature" "+xsaveopt" "-target-feature" "+rdrnd" "-target-feature" "-avx512f" "-target-feature" "-amx-bf16" "-target-feature" "-avx512bf16" "-target-feature" "-avx512vnni" "-target-feature" "-push2pop2" "-target-feature" "+cx8" "-target-feature" "-avx512bw" "-target-feature" "+sse3" "-target-feature" "-pku" "-target-feature" "-nf" "-target-feature" "-amx-tf32" "-target-feature" "-amx-avx512" "-target-feature" "+fsgsbase" "-target-feature" "-clzero" "-target-feature" "-mwaitx" "-target-feature" "-lwp" "-target-feature" "+lzcnt" "-target-feature" "-sha" "-target-feature" "-movdir64b" "-target-feature" "-ppx" "-target-feature" "-wbnoinvd" "-target-feature" "-enqcmd" "-target-feature" "-amx-transpose" "-target-feature" "-avx10.2-512" "-target-feature" "-avxneconvert" "-target-feature" "-tbm" "-target-feature" "-pconfig" "-target-feature" "-amx-complex" "-target-feature" "+ssse3" "-target-feature" "+cx16" "-target-feature" "+bmi2" "-target-feature" "+fma" "-target-feature" "+popcnt" "-target-feature" "-avxifma" "-target-feature" "+f16c" "-target-feature" "-avx512bitalg" "-target-feature" "-rdpru" "-target-feature" "-clwb" "-target-feature" "+mmx" "-target-feature" "+sse2" "-target-feature" "-rdseed" "-target-feature" "-avx512vbmi2" "-target-feature" "-prefetchi" "-target-feature" "-amx-movrs" "-target-feature" "-rdpid" "-target-feature" "-fma4" "-target-feature" "-avx512vbmi" "-target-feature" "-shstk" "-target-feature" "-vaes" "-target-feature" "-waitpkg" "-target-feature" "-sgx" "-target-feature" "+fxsr" "-target-feature" "-avx512dq" "-target-feature" "-sse4a" "-debugger-tuning=gdb" "-fdebug-compilation-dir=/home/usr00/_gitea/torch-trainer" "-fcoverage-compilation-dir=/home/usr00/_gitea/torch-trainer" "-resource-dir" "/usr/lib/llvm-21/lib/clang/21" "-internal-isystem" "/usr/lib/llvm-21/lib/clang/21/include" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-ferror-limit" "19" "-fmessage-length=120" "-fgnuc-version=4.2.1" "-fskip-odr-check-in-gmf" "-fcolor-diagnostics" "-faddrsig" "-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o" "-" "-x" "c" "-"

gcc -Q -march=native --help=target | grep -v "\[disabled\]"

The following options are target specific:
 -m128bit-long-double [enabled]
 -m64 [enabled]
 -m80387 [enabled]
 -mabi= sysv
 -mabm [enabled]
 -maddress-mode= long
 -maes [enabled]
 -malign-data= compat
 -malign-functions= 0
 -malign-jumps= 0
 -malign-loops= 0
 -malign-stringops [enabled]
 -mapx-features= none
 -march= haswell
 -masm= att
 -mavx [enabled]
 -mavx10.1 -mavx10.1-256
 -mavx2 [enabled]
 -mbmi [enabled]
 -mbmi2 [enabled]
 -mbranch-cost=<0,5> 3
 -mcmodel= [default]
 -mcpu=
 -mcrc32 [enabled]
 -mcx16 [enabled]
 -mdirect-extern-access [enabled]
 -mf16c [enabled]
 -mfancy-math-387 [enabled]
 -mfentry-name=
 -mfentry-section=
 -mfma [enabled]
 -mfp-ret-in-387 [enabled]
 -mfpmath= sse
 -mfsgsbase [enabled]
 -mfunction-return= keep
 -mfused-madd -ffp-contract=fast
 -mfxsr [enabled]
 -mgather -mtune-ctrl=use_gather
 -mglibc [enabled]
 -mhard-float [enabled]
 -mharden-sls= none
 -mhle [enabled]
 -mieee-fp [enabled]
 -mincoming-stack-boundary= 0
 -mindirect-branch= keep
 -minstrument-return= none
 -mintel-syntax -masm=intel
 -mlam= none
 -mlarge-data-threshold=<number> 65536
 -mlong-double-80 [enabled]
 -mlzcnt [enabled]
 -mmemcpy-strategy=
 -mmemset-strategy=
 -mmmx [enabled]
 -mmovbe [enabled]
 -mmove-max= 256
 -mmwait [enabled]
 -mpartial-vector-fp-math [enabled]
 -mpclmul [enabled]
 -mpopcnt [enabled]
 -mprefer-avx128 -mprefer-vector-width=128
 -mprefer-vector-width= none
 -mpreferred-stack-boundary= 0
 -mpush-args [enabled]
 -mrdrnd [enabled]
 -mrecip=
 -mred-zone [enabled]
 -mregparm= 6
 -msahf [enabled]
 -mscatter -mtune-ctrl=use_scatter
 -msse [enabled]
 -msse2 [enabled]
 -msse3 [enabled]
 -msse4 [enabled]
 -msse4.1 [enabled]
 -msse4.2 [enabled]
 -msse5 -mavx
 -mssse3 [enabled]
 -mstack-protector-guard-offset=
 -mstack-protector-guard-reg=
 -mstack-protector-guard-symbol=
 -mstack-protector-guard= tls
 -mstore-max= 256
 -mstringop-strategy= [default]
 -mstv [enabled]
 -mtls-dialect= gnu
 -mtls-direct-seg-refs [enabled]
 -mtune-ctrl=
 -mtune= haswell
 -mveclibabi= [default]
 -mxsave [enabled]
 -mxsaveopt [enabled]

 Known assembler dialects (for use with the -masm= option):
 att intel

 Known ABIs (for use with the -mabi= option):
 ms sysv

 Known code models (for use with the -mcmodel= option):
 32 kernel large medium small

 Valid arguments to -mfpmath=:
 387 387+sse 387,sse both sse sse+387 sse,387

 Known choices for mitigation against straight line speculation with -mharden-sls=:
 all indirect-jmp none return

 Known indirect branch choices (for use with the -mindirect-branch=/-mfunction-return= options):
 keep thunk thunk-extern thunk-inline

 Known choices for return instrumentation with -minstrument-return=:
 call none nop5

 Known data alignment choices (for use with the -malign-data= option):
 abi cacheline compat

 Known vectorization library ABIs (for use with the -mveclibabi= option):
 acml svml

 Known address mode (for use with the -maddress-mode= option):
 long short

 Known preferred register vector length (to use with the -mprefer-vector-width= option):
 128 256 512 none

 Known stack protector guard (for use with the -mstack-protector-guard= option):
 global tls

 Valid arguments to -mstringop-strategy=:
 byte_loop libcall loop rep_4byte rep_8byte rep_byte unrolled_loop vector_loop

 Known TLS dialects (for use with the -mtls-dialect= option):
 gnu gnu2

 Known valid arguments for -march= option:
 i386 i486 i586 pentium lakemont pentium-mmx winchip-c6 winchip2 c3 samuel-2 c3-2 nehemiah c7 esther i686 pentiumpro pentium2 pentium3 pentium3m pentium-m pentium4 pentium4m prescott nocona core2 nehalem corei7 westmere sandybridge corei7-avx ivybridge core-avx-i haswell core-avx2 broadwell skylake skylake-avx512 cannonlake icelake-client rocketlake icelake-server cascadelake tigerlake cooperlake sapphirerapids emeraldrapids alderlake raptorlake meteorlake graniterapids graniterapids-d arrowlake arrowlake-s lunarlake pantherlake bonnell atom silvermont slm goldmont goldmont-plus tremont gracemont sierraforest grandridge clearwaterforest knl knm intel geode k6 k6-2 k6-3 athlon athlon-tbird athlon-4 athlon-xp athlon-mp x86-64 x86-64-v2 x86-64-v3 x86-64-v4 eden-x2 nano nano-1000 nano-2000 nano-3000 nano-x2 eden-x4 nano-x4 lujiazui yongfeng k8 k8-sse3 opteron opteron-sse3 athlon64 athlon64-sse3 athlon-fx amdfam10 barcelona bdver1 bdver2 bdver3 bdver4 znver1 znver2 znver3 znver4 znver5 btver1 btver2 generic native

 Known valid arguments for -mtune= option:
 generic i386 i486 pentium lakemont pentiumpro pentium4 nocona core2 nehalem sandybridge haswell bonnell silvermont goldmont goldmont-plus tremont sierraforest grandridge clearwaterforest knl knm skylake skylake-avx512 cannonlake icelake-client icelake-server cascadelake tigerlake cooperlake sapphirerapids alderlake rocketlake graniterapids graniterapids-d arrowlake arrowlake-s pantherlake intel lujiazui yongfeng geode k6 athlon k8 amdfam10 bdver1 bdver2 bdver3 bdver4 btver1 btver2 znver1 znver2 znver3 znver4 znver5

AMD Ryzen 7 PRO 7840U w/ Radeon 780M Graphics - Ubuntu 24.04

clang -E - -march=native -###

Ubuntu clang version 21.1.8 (++20251202083326+f68f64eb8130-1~exp1~20251202083450.66)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-21/bin
 (in-process)
 "/usr/lib/llvm-21/bin/clang" "-cc1" "-triple" "x86_64-pc-linux-gnu" "-E" "-disable-free" "-clear-ast-before-backend" "-disable-llvm-verifier" "-discard-value-names" "-main-file-name" "-" "-mrelocation-model" "pic" "-pic-level" "2" "-pic-is-pie" "-mframe-pointer=all" "-fmath-errno" "-ffp-contract=on" "-fno-rounding-math" "-mconstructor-aliases" "-funwind-tables=2" "-target-cpu" "znver4" "-target-feature" "+prfchw" "-target-feature" "-cldemote" "-target-feature" "+avx" "-target-feature" "+aes" "-target-feature" "+sahf" "-target-feature" "+pclmul" "-target-feature" "-xop" "-target-feature" "+crc32" "-target-feature" "-amx-fp8" "-target-feature" "+xsaves" "-target-feature" "-avx512fp16" "-target-feature" "-usermsr" "-target-feature" "-sm4" "-target-feature" "-egpr" "-target-feature" "+sse4.1" "-target-feature" "+avx512ifma" "-target-feature" "+xsave" "-target-feature" "+sse4.2" "-target-feature" "-tsxldtrk" "-target-feature" "-sm3" "-target-feature" "-ptwrite" "-target-feature" "-widekl" "-target-feature" "-movrs" "-target-feature" "+invpcid" "-target-feature" "+64bit" "-target-feature" "+xsavec" "-target-feature" "-avx10.1-512" "-target-feature" "+avx512vpopcntdq" "-target-feature" "+cmov" "-target-feature" "-avx512vp2intersect" "-target-feature" "+avx512cd" "-target-feature" "+movbe" "-target-feature" "-avxvnniint8" "-target-feature" "-ccmp" "-target-feature" "-amx-int8" "-target-feature" "-kl" "-target-feature" "-avx10.1-256" "-target-feature" "+evex512" "-target-feature" "-avxvnni" "-target-feature" "-rtm" "-target-feature" "+adx" "-target-feature" "+avx2" "-target-feature" "-hreset" "-target-feature" "-movdiri" "-target-feature" "-serialize" "-target-feature" "-sha512" "-target-feature" "+vpclmulqdq" "-target-feature" "+avx512vl" "-target-feature" "-uintr" "-target-feature" "-cf" "-target-feature" "+clflushopt" "-target-feature" "-raoint" "-target-feature" "-cmpccxadd" "-target-feature" "+bmi" "-target-feature" "-amx-tile" "-target-feature" "+sse" "-target-feature" "-avx10.2-256" "-target-feature" "+gfni" "-target-feature" "-avxvnniint16" "-target-feature" "-amx-fp16" "-target-feature" "-zu" "-target-feature" "-ndd" "-target-feature" "+xsaveopt" "-target-feature" "+rdrnd" "-target-feature" "+avx512f" "-target-feature" "-amx-bf16" "-target-feature" "+avx512bf16" "-target-feature" "+avx512vnni" "-target-feature" "-push2pop2" "-target-feature" "+cx8" "-target-feature" "+avx512bw" "-target-feature" "+sse3" "-target-feature" "-pku" "-target-feature" "-nf" "-target-feature" "-amx-tf32" "-target-feature" "-amx-avx512" "-target-feature" "+fsgsbase" "-target-feature" "+clzero" "-target-feature" "-mwaitx" "-target-feature" "-lwp" "-target-feature" "+lzcnt" "-target-feature" "+sha" "-target-feature" "-movdir64b" "-target-feature" "-ppx" "-target-feature" "-wbnoinvd" "-target-feature" "-enqcmd" "-target-feature" "-amx-transpose" "-target-feature" "-avx10.2-512" "-target-feature" "-avxneconvert" "-target-feature" "-tbm" "-target-feature" "-pconfig" "-target-feature" "-amx-complex" "-target-feature" "+ssse3" "-target-feature" "+cx16" "-target-feature" "+bmi2" "-target-feature" "+fma" "-target-feature" "+popcnt" "-target-feature" "-avxifma" "-target-feature" "+f16c" "-target-feature" "+avx512bitalg" "-target-feature" "-rdpru" "-target-feature" "+clwb" "-target-feature" "+mmx" "-target-feature" "+sse2" "-target-feature" "+rdseed" "-target-feature" "+avx512vbmi2" "-target-feature" "-prefetchi" "-target-feature" "-amx-movrs" "-target-feature" "+rdpid" "-target-feature" "-fma4" "-target-feature" "+avx512vbmi" "-target-feature" "+shstk" "-target-feature" "+vaes" "-target-feature" "-waitpkg" "-target-feature" "-sgx" "-target-feature" "+fxsr" "-target-feature" "+avx512dq" "-target-feature" "+sse4a" "-debugger-tuning=gdb" "-fdebug-compilation-dir=/home/usr00" "-fcoverage-compilation-dir=/home/usr00" "-resource-dir" "/usr/lib/llvm-21/lib/clang/21" "-internal-isystem" "/usr/lib/llvm-21/lib/clang/21/include" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-ferror-limit" "19" "-fmessage-length=120" "-fgnuc-version=4.2.1" "-fskip-odr-check-in-gmf" "-fcolor-diagnostics" "-faddrsig" "-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o" "-" "-x" "c" "-"

gcc -Q -march=native --help=target | grep -v "\[disabled\]"

The following options are target specific:
 -m128bit-long-double [enabled]
 -m64 [enabled]
 -m80387 [enabled]
 -mabi= sysv
 -mabm [enabled]
 -maddress-mode= long
 -madx [enabled]
 -maes [enabled]
 -malign-data= compat
 -malign-functions= 0
 -malign-jumps= 0
 -malign-loops= 0
 -malign-stringops [enabled]
 -mapx-features= none
 -march= znver4
 -masm= att
 -mavx [enabled]
 -mavx10.1 -mavx10.1-256
 -mavx2 [enabled]
 -mavx512bf16 [enabled]
 -mavx512bitalg [enabled]
 -mavx512bw [enabled]
 -mavx512cd [enabled]
 -mavx512dq [enabled]
 -mavx512f [enabled]
 -mavx512ifma [enabled]
 -mavx512vbmi [enabled]
 -mavx512vbmi2 [enabled]
 -mavx512vl [enabled]
 -mavx512vnni [enabled]
 -mavx512vpopcntdq [enabled]
 -mbmi [enabled]
 -mbmi2 [enabled]
 -mbranch-cost=<0,5> 3
 -mclflushopt [enabled]
 -mclwb [enabled]
 -mclzero [enabled]
 -mcmodel= [default]
 -mcpu=
 -mcrc32 [enabled]
 -mcx16 [enabled]
 -mdirect-extern-access [enabled]
 -mevex512 [enabled]
 -mf16c [enabled]
 -mfancy-math-387 [enabled]
 -mfentry-name=
 -mfentry-section=
 -mfma [enabled]
 -mfp-ret-in-387 [enabled]
 -mfpmath= sse
 -mfsgsbase [enabled]
 -mfunction-return= keep
 -mfused-madd -ffp-contract=fast
 -mfxsr [enabled]
 -mgather -mtune-ctrl=use_gather
 -mgfni [enabled]
 -mglibc [enabled]
 -mhard-float [enabled]
 -mharden-sls= none
 -mieee-fp [enabled]
 -mincoming-stack-boundary= 0
 -mindirect-branch= keep
 -minstrument-return= none
 -mintel-syntax -masm=intel
 -mlam= none
 -mlarge-data-threshold=<number> 65536
 -mlong-double-80 [enabled]
 -mlzcnt [enabled]
 -mmemcpy-strategy=
 -mmemset-strategy=
 -mmmx [enabled]
 -mmovbe [enabled]
 -mmove-max= 512
 -mmwait [enabled]
 -mpartial-vector-fp-math [enabled]
 -mpclmul [enabled]
 -mpopcnt [enabled]
 -mprefer-avx128 -mprefer-vector-width=128
 -mprefer-vector-width= none
 -mpreferred-stack-boundary= 0
 -mprfchw [enabled]
 -mpush-args [enabled]
 -mrdpid [enabled]
 -mrdrnd [enabled]
 -mrdseed [enabled]
 -mrecip=
 -mred-zone [enabled]
 -mregparm= 6
 -msahf [enabled]
 -mscatter -mtune-ctrl=use_scatter
 -msha [enabled]
 -mshstk [enabled]
 -msse [enabled]
 -msse2 [enabled]
 -msse3 [enabled]
 -msse4 [enabled]
 -msse4.1 [enabled]
 -msse4.2 [enabled]
 -msse4a [enabled]
 -msse5 -mavx
 -mssse3 [enabled]
 -mstack-protector-guard-offset=
 -mstack-protector-guard-reg=
 -mstack-protector-guard-symbol=
 -mstack-protector-guard= tls
 -mstore-max= 512
 -mstringop-strategy= [default]
 -mstv [enabled]
 -mtls-dialect= gnu
 -mtls-direct-seg-refs [enabled]
 -mtune-ctrl=
 -mtune= znver4
 -mvaes [enabled]
 -mveclibabi= [default]
 -mvpclmulqdq [enabled]
 -mxsave [enabled]
 -mxsavec [enabled]
 -mxsaveopt [enabled]
 -mxsaves [enabled]

 Known assembler dialects (for use with the -masm= option):
 att intel

 Known ABIs (for use with the -mabi= option):
 ms sysv

 Known code models (for use with the -mcmodel= option):
 32 kernel large medium small

 Valid arguments to -mfpmath=:
 387 387+sse 387,sse both sse sse+387 sse,387

 Known choices for mitigation against straight line speculation with -mharden-sls=:
 all indirect-jmp none return

 Known indirect branch choices (for use with the -mindirect-branch=/-mfunction-return= options):
 keep thunk thunk-extern thunk-inline

 Known choices for return instrumentation with -minstrument-return=:
 call none nop5

 Known data alignment choices (for use with the -malign-data= option):
 abi cacheline compat

 Known vectorization library ABIs (for use with the -mveclibabi= option):
 acml svml

 Known address mode (for use with the -maddress-mode= option):
 long short

 Known preferred register vector length (to use with the -mprefer-vector-width= option):
 128 256 512 none

 Known stack protector guard (for use with the -mstack-protector-guard= option):
 global tls

 Valid arguments to -mstringop-strategy=:
 byte_loop libcall loop rep_4byte rep_8byte rep_byte unrolled_loop vector_loop

 Known TLS dialects (for use with the -mtls-dialect= option):
 gnu gnu2

 Known valid arguments for -march= option:
 i386 i486 i586 pentium lakemont pentium-mmx winchip-c6 winchip2 c3 samuel-2 c3-2 nehemiah c7 esther i686 pentiumpro pentium2 pentium3 pentium3m pentium-m pentium4 pentium4m prescott nocona core2 nehalem corei7 westmere sandybridge corei7-avx ivybridge core-avx-i haswell core-avx2 broadwell skylake skylake-avx512 cannonlake icelake-client rocketlake icelake-server cascadelake tigerlake cooperlake sapphirerapids emeraldrapids alderlake raptorlake meteorlake graniterapids graniterapids-d arrowlake arrowlake-s lunarlake pantherlake bonnell atom silvermont slm goldmont goldmont-plus tremont gracemont sierraforest grandridge clearwaterforest knl knm intel geode k6 k6-2 k6-3 athlon athlon-tbird athlon-4 athlon-xp athlon-mp x86-64 x86-64-v2 x86-64-v3 x86-64-v4 eden-x2 nano nano-1000 nano-2000 nano-3000 nano-x2 eden-x4 nano-x4 lujiazui yongfeng k8 k8-sse3 opteron opteron-sse3 athlon64 athlon64-sse3 athlon-fx amdfam10 barcelona bdver1 bdver2 bdver3 bdver4 znver1 znver2 znver3 znver4 znver5 btver1 btver2 generic native

 Known valid arguments for -mtune= option:
 generic i386 i486 pentium lakemont pentiumpro pentium4 nocona core2 nehalem sandybridge haswell bonnell silvermont goldmont goldmont-plus tremont sierraforest grandridge clearwaterforest knl knm skylake skylake-avx512 cannonlake icelake-client icelake-server cascadelake tigerlake cooperlake sapphirerapids alderlake rocketlake graniterapids graniterapids-d arrowlake arrowlake-s pantherlake intel lujiazui yongfeng geode k6 athlon k8 amdfam10 bdver1 bdver2 bdver3 bdver4 btver1 btver2 znver1 znver2 znver3 znver4 znver5

Intel(R) Xeon(R) CPU E3-1245 V2 @ 3.40GHz - Ubuntu 20.04

gcc -Q -march=native --help=target | grep -v "\[disabled\]"

The following options are target specific:
 -m128bit-long-double [enabled]
 -m64 [enabled]
 -m80387 [enabled]
 -mabi= sysv
 -maddress-mode= long
 -maes [enabled]
 -malign-data= compat
 -malign-functions= 0
 -malign-jumps= 0
 -malign-loops= 0
 -malign-stringops [enabled]
 -march= ivybridge
 -masm= att
 -mavx [enabled]
 -mavx256-split-unaligned-load [enabled]
 -mavx256-split-unaligned-store [enabled]
 -mbranch-cost=<0,5> 3
 -mcmodel= [default]
 -mcpu=
 -mcrc32 [enabled]
 -mcx16 [enabled]
 -mf16c [enabled]
 -mfancy-math-387 [enabled]
 -mfentry-name=
 -mfentry-section=
 -mfp-ret-in-387 [enabled]
 -mfpmath= sse
 -mfsgsbase [enabled]
 -mfunction-return= keep
 -mfused-madd -ffp-contract=fast
 -mfxsr [enabled]
 -mglibc [enabled]
 -mhard-float [enabled]
 -mharden-sls= none
 -mieee-fp [enabled]
 -mincoming-stack-boundary= 0
 -mindirect-branch= keep
 -minstrument-return= none
 -mintel-syntax -masm=intel
 -mlarge-data-threshold=<number> 65536
 -mlong-double-80 [enabled]
 -mmemcpy-strategy=
 -mmemset-strategy=
 -mmmx [enabled]
 -mmwait [enabled]
 -mpclmul [enabled]
 -mpopcnt [enabled]
 -mprefer-avx128 -mprefer-vector-width=128
 -mprefer-vector-width= none
 -mpreferred-stack-boundary= 0
 -mpush-args [enabled]
 -mrdrnd [enabled]
 -mrecip=
 -mred-zone [enabled]
 -mregparm= 6
 -msahf [enabled]
 -msse [enabled]
 -msse2 [enabled]
 -msse3 [enabled]
 -msse4 [enabled]
 -msse4.1 [enabled]
 -msse4.2 [enabled]
 -msse5 -mavx
 -mssse3 [enabled]
 -mstack-protector-guard-offset=
 -mstack-protector-guard-reg=
 -mstack-protector-guard-symbol=
 -mstack-protector-guard= tls
 -mstringop-strategy= [default]
 -mstv [enabled]
 -mtls-dialect= gnu
 -mtls-direct-seg-refs [enabled]
 -mtune-ctrl=
 -mtune= ivybridge
 -mveclibabi= [default]
 -mvzeroupper [enabled]
 -mxsave [enabled]
 -mxsaveopt [enabled]

 Known assembler dialects (for use with the -masm= option):
 att intel

 Known ABIs (for use with the -mabi= option):
 ms sysv

 Known code models (for use with the -mcmodel= option):
 32 kernel large medium small

 Valid arguments to -mfpmath=:
 387 387+sse 387,sse both sse sse+387 sse,387

 Known choices for mitigation against straight line speculation with -mharden-s ls=:
 all indirect-jmp none return

 Known indirect branch choices (for use with the -mindirect-branch=/-mfunction- return= options):
 keep thunk thunk-extern thunk-inline

 Known choices for return instrumentation with -minstrument-return=:
 call none nop5

 Known data alignment choices (for use with the -malign-data= option):
 abi cacheline compat

 Known vectorization library ABIs (for use with the -mveclibabi= option):
 acml svml

 Known address mode (for use with the -maddress-mode= option):
 long short

 Known preferred register vector length (to use with the -mprefer-vector-width= option):
 128 256 512 none

 Known stack protector guard (for use with the -mstack-protector-guard= option) :
 global tls

 Valid arguments to -mstringop-strategy=:
 byte_loop libcall loop rep_4byte rep_8byte rep_byte unrolled_loop
 vector_loop

 Known TLS dialects (for use with the -mtls-dialect= option):
 gnu gnu2

 Known valid arguments for -march= option:
 i386 i486 i586 pentium lakemont pentium-mmx winchip-c6 winchip2 c3 samuel-2 c3-2 nehemiah c7 esther i686 pentiumpro pentium2 pentium3 pentium3m pentium-m pe ntium4 pentium4m prescott nocona core2 nehalem corei7 westmere sandybridge corei 7-avx ivybridge core-avx-i haswell core-avx2 broadwell skylake skylake-avx512 ca nnonlake icelake-client rocketlake icelake-server cascadelake tigerlake cooperla ke sapphirerapids alderlake bonnell atom silvermont slm goldmont goldmont-plus t remont knl knm intel geode k6 k6-2 k6-3 athlon athlon-tbird athlon-4 athlon-xp a thlon-mp x86-64 x86-64-v2 x86-64-v3 x86-64-v4 eden-x2 nano nano-1000 nano-2000 n ano-3000 nano-x2 eden-x4 nano-x4 k8 k8-sse3 opteron opteron-sse3 athlon64 athlon 64-sse3 athlon-fx amdfam10 barcelona bdver1 bdver2 bdver3 bdver4 znver1 znver2 z nver3 btver1 btver2 generic native

 Known valid arguments for -mtune= option:
 generic i386 i486 pentium lakemont pentiumpro pentium4 nocona core2 nehalem sandybridge haswell bonnell silvermont goldmont goldmont-plus tremont knl knm sk ylake skylake-avx512 cannonlake icelake-client icelake-server cascadelake tigerl ake cooperlake sapphirerapids alderlake rocketlake intel geode k6 athlon k8 amdf am10 bdver1 bdver2 bdver3 bdver4 btver1 btver2 znver1 znver2 znver3

Intel(R) Xeon(R) E-2234 CPU @ 3.60GHz - Ubuntu 24.04

clang -E - -march=native -###

Ubuntu clang version 21.1.8 (++20251202083326+f68f64eb8130-1~exp1~20251202083450.66)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-21/bin
 (in-process)
 "/usr/lib/llvm-21/bin/clang" "-cc1" "-triple" "x86_64-pc-linux-gnu" "-E" "-disable-free" "-clear-ast-before-backend" "-disable-llvm-verifier" "-discard-value-names" "-main-file-name" "-" "-mrelocation-model" "pic" "-pic-level" "2" "-pic-is-pie" "-mframe-pointer=all" "-fmath-errno" "-ffp-contract=on" "-fno-rounding-math" "-mconstructor-aliases" "-funwind-tables=2" "-target-cpu" "skylake" "-target-feature" "+prfchw" "-target-feature" "-cldemote" "-target-feature" "+avx" "-target-feature" "+aes" "-target-feature" "+sahf" "-target-feature" "+pclmul" "-target-feature" "-xop" "-target-feature" "+crc32" "-target-feature" "-amx-fp8" "-target-feature" "+xsaves" "-target-feature" "-avx512fp16" "-target-feature" "-usermsr" "-target-feature" "-sm4" "-target-feature" "-egpr" "-target-feature" "+sse4.1" "-target-feature" "-avx512ifma" "-target-feature" "+xsave" "-target-feature" "+sse4.2" "-target-feature" "-tsxldtrk" "-target-feature" "-sm3" "-target-feature" "-ptwrite" "-target-feature" "-widekl" "-target-feature" "-movrs" "-target-feature" "+invpcid" "-target-feature" "+64bit" "-target-feature" "+xsavec" "-target-feature" "-avx10.1-512" "-target-feature" "-avx512vpopcntdq" "-target-feature" "+cmov" "-target-feature" "-avx512vp2intersect" "-target-feature" "-avx512cd" "-target-feature" "+movbe" "-target-feature" "-avxvnniint8" "-target-feature" "-ccmp" "-target-feature" "-amx-int8" "-target-feature" "-kl" "-target-feature" "-avx10.1-256" "-target-feature" "-sha512" "-target-feature" "-avxvnni" "-target-feature" "-rtm" "-target-feature" "+adx" "-target-feature" "+avx2" "-target-feature" "-hreset" "-target-feature" "-movdiri" "-target-feature" "-serialize" "-target-feature" "-vpclmulqdq" "-target-feature" "-avx512vl" "-target-feature" "-uintr" "-target-feature" "-cf" "-target-feature" "+clflushopt" "-target-feature" "-raoint" "-target-feature" "-cmpccxadd" "-target-feature" "+bmi" "-target-feature" "-amx-tile" "-target-feature" "+sse" "-target-feature" "-avx10.2-256" "-target-feature" "-gfni" "-target-feature" "-avxvnniint16" "-target-feature" "-amx-fp16" "-target-feature" "-zu" "-target-feature" "-ndd" "-target-feature" "+xsaveopt" "-target-feature" "+rdrnd" "-target-feature" "-avx512f" "-target-feature" "-amx-bf16" "-target-feature" "-avx512bf16" "-target-feature" "-avx512vnni" "-target-feature" "-push2pop2" "-target-feature" "+cx8" "-target-feature" "-avx512bw" "-target-feature" "+sse3" "-target-feature" "-pku" "-target-feature" "-nf" "-target-feature" "-amx-tf32" "-target-feature" "-amx-avx512" "-target-feature" "+fsgsbase" "-target-feature" "-clzero" "-target-feature" "-mwaitx" "-target-feature" "-lwp" "-target-feature" "+lzcnt" "-target-feature" "-sha" "-target-feature" "-movdir64b" "-target-feature" "-ppx" "-target-feature" "-wbnoinvd" "-target-feature" "-enqcmd" "-target-feature" "-amx-transpose" "-target-feature" "-avx10.2-512" "-target-feature" "-avxneconvert" "-target-feature" "-tbm" "-target-feature" "-pconfig" "-target-feature" "-amx-complex" "-target-feature" "+ssse3" "-target-feature" "+cx16" "-target-feature" "+bmi2" "-target-feature" "+fma" "-target-feature" "+popcnt" "-target-feature" "-avxifma" "-target-feature" "+f16c" "-target-feature" "-avx512bitalg" "-target-feature" "-rdpru" "-target-feature" "-clwb" "-target-feature" "+mmx" "-target-feature" "+sse2" "-target-feature" "+rdseed" "-target-feature" "-avx512vbmi2" "-target-feature" "-prefetchi" "-target-feature" "-amx-movrs" "-target-feature" "-rdpid" "-target-feature" "-fma4" "-target-feature" "-avx512vbmi" "-target-feature" "-shstk" "-target-feature" "-vaes" "-target-feature" "-waitpkg" "-target-feature" "-sgx" "-target-feature" "+fxsr" "-target-feature" "-avx512dq" "-target-feature" "-sse4a" "-debugger-tuning=gdb" "-fdebug-compilation-dir=/home/usr00" "-fcoverage-compilation-dir=/home/usr00" "-resource-dir" "/usr/lib/llvm-21/lib/clang/21" "-internal-isystem" "/usr/lib/llvm-21/lib/clang/21/include" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-ferror-limit" "19" "-fmessage-length=237" "-fgnuc-version=4.2.1" "-fskip-odr-check-in-gmf" "-fcolor-diagnostics" "-faddrsig" "-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o" "-" "-x" "c" "-"

gcc -Q -march=native --help=target | grep -v "\[disabled\]"

The following options are target specific:
 -m128bit-long-double [enabled]
 -m64 [enabled]
 -m80387 [enabled]
 -mabi= sysv
 -mabm [enabled]
 -maddress-mode= long
 -madx [enabled]
 -maes [enabled]
 -malign-data= compat
 -malign-functions= 0
 -malign-jumps= 0
 -malign-loops= 0
 -malign-stringops [enabled]
 -mapx-features= none
 -march= skylake
 -masm= att
 -mavx [enabled]
 -mavx10.1 -mavx10.1-256
 -mavx2 [enabled]
 -mbmi [enabled]
 -mbmi2 [enabled]
 -mbranch-cost=<0,5> 3
 -mclflushopt [enabled]
 -mcmodel= [default]
 -mcpu=
 -mcrc32 [enabled]
 -mcx16 [enabled]
 -mdirect-extern-access [enabled]
 -mf16c [enabled]
 -mfancy-math-387 [enabled]
 -mfentry-name=
 -mfentry-section=
 -mfma [enabled]
 -mfp-ret-in-387 [enabled]
 -mfpmath= sse
 -mfsgsbase [enabled]
 -mfunction-return= keep
 -mfused-madd -ffp-contract=fast
 -mfxsr [enabled]
 -mgather -mtune-ctrl=use_gather
 -mglibc [enabled]
 -mhard-float [enabled]
 -mharden-sls= none
 -mhle [enabled]
 -mieee-fp [enabled]
 -mincoming-stack-boundary= 0
 -mindirect-branch= keep
 -minstrument-return= none
 -mintel-syntax -masm=intel
 -mlam= none
 -mlarge-data-threshold=<number> 65536
 -mlong-double-80 [enabled]
 -mlzcnt [enabled]
 -mmemcpy-strategy=
 -mmemset-strategy=
 -mmmx [enabled]
 -mmovbe [enabled]
 -mmove-max= 256
 -mmwait [enabled]
 -mpartial-vector-fp-math [enabled]
 -mpclmul [enabled]
 -mpopcnt [enabled]
 -mprefer-avx128 -mprefer-vector-width=128
 -mprefer-vector-width= none
 -mpreferred-stack-boundary= 0
 -mprfchw [enabled]
 -mpush-args [enabled]
 -mrdrnd [enabled]
 -mrdseed [enabled]
 -mrecip=
 -mred-zone [enabled]
 -mregparm= 6
 -msahf [enabled]
 -mscatter -mtune-ctrl=use_scatter
 -msse [enabled]
 -msse2 [enabled]
 -msse3 [enabled]
 -msse4 [enabled]
 -msse4.1 [enabled]
 -msse4.2 [enabled]
 -msse5 -mavx
 -mssse3 [enabled]
 -mstack-protector-guard-offset=
 -mstack-protector-guard-reg=
 -mstack-protector-guard-symbol=
 -mstack-protector-guard= tls
 -mstore-max= 256
 -mstringop-strategy= [default]
 -mstv [enabled]
 -mtls-dialect= gnu
 -mtls-direct-seg-refs [enabled]
 -mtune-ctrl=
 -mtune= skylake
 -mveclibabi= [default]
 -mxsave [enabled]
 -mxsavec [enabled]
 -mxsaveopt [enabled]
 -mxsaves [enabled]

 Known assembler dialects (for use with the -masm= option):
 att intel

 Known ABIs (for use with the -mabi= option):
 ms sysv

 Known code models (for use with the -mcmodel= option):
 32 kernel large medium small

 Valid arguments to -mfpmath=:
 387 387+sse 387,sse both sse sse+387 sse,387

 Known choices for mitigation against straight line speculation with -mharden-sls=:
 all indirect-jmp none return

 Known indirect branch choices (for use with the -mindirect-branch=/-mfunction-return= options):
 keep thunk thunk-extern thunk-inline

 Known choices for return instrumentation with -minstrument-return=:
 call none nop5

 Known data alignment choices (for use with the -malign-data= option):
 abi cacheline compat

 Known vectorization library ABIs (for use with the -mveclibabi= option):
 acml svml

 Known address mode (for use with the -maddress-mode= option):
 long short

 Known preferred register vector length (to use with the -mprefer-vector-width= option):
 128 256 512 none

 Known stack protector guard (for use with the -mstack-protector-guard= option):
 global tls

 Valid arguments to -mstringop-strategy=:
 byte_loop libcall loop rep_4byte rep_8byte rep_byte unrolled_loop vector_loop

 Known TLS dialects (for use with the -mtls-dialect= option):
 gnu gnu2

 Known valid arguments for -march= option:
 i386 i486 i586 pentium lakemont pentium-mmx winchip-c6 winchip2 c3 samuel-2 c3-2 nehemiah c7 esther i686 pentiumpro pentium2 pentium3 pentium3m pentium-m pentium4 pentium4m prescott nocona core2 nehalem corei7 westmere sandybridge corei7-avx ivybridge core-avx-i haswell core-avx2 broadwell skylake skylake-avx512 cannonlake icelake-client rocketlake icelake-server cascadelake tigerlake cooperlake sapphirerapids emeraldrapids alderlake raptorlake meteorlake graniterapids graniterapids-d arrowlake arrowlake-s lunarlake pantherlake bonnell atom silvermont slm goldmont goldmont-plus tremont gracemont sierraforest grandridge clearwaterforest knl knm intel geode k6 k6-2 k6-3 athlon athlon-tbird athlon-4 athlon-xp athlon-mp x86-64 x86-64-v2 x86-64-v3 x86-64-v4 eden-x2 nano nano-1000 nano-2000 nano-3000 nano-x2 eden-x4 nano-x4 lujiazui yongfeng k8 k8-sse3 opteron opteron-sse3 athlon64 athlon64-sse3 athlon-fx amdfam10 barcelona bdver1 bdver2 bdver3 bdver4 znver1 znver2 znver3 znver4 znver5 btver1 btver2 generic native

 Known valid arguments for -mtune= option:
 generic i386 i486 pentium lakemont pentiumpro pentium4 nocona core2 nehalem sandybridge haswell bonnell silvermont goldmont goldmont-plus tremont sierraforest grandridge clearwaterforest knl knm skylake skylake-avx512 cannonlake icelake-client icelake-server cascadelake tigerlake cooperlake sapphirerapids alderlake rocketlake graniterapids graniterapids-d arrowlake arrowlake-s pantherlake intel lujiazui yongfeng geode k6 athlon k8 amdfam10 bdver1 bdver2 bdver3 bdver4 btver1 btver2 znver1 znver2 znver3 znver4 znver5

Intel(R) Core(TM) i7-3770K CPU @ 3.50GHz - Ubuntu 24.04

clang -E - -march=native -###

Ubuntu clang version 21.1.8 (++20251202083326+f68f64eb8130-1~exp1~20251202083450.66)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-21/bin
 (in-process)
 "/usr/lib/llvm-21/bin/clang" "-cc1" "-triple" "x86_64-pc-linux-gnu" "-E" "-disable-free" "-clear-ast-before-backend" "-disable-llvm-verifier" "-discard-value-names" "-main-file-name" "-" "-mrelocation-model" "pic" "-pic-level" "2" "-pic-is-pie" "-mframe-pointer=all" "-fmath-errno" "-ffp-contract=on" "-fno-rounding-math" "-mconstructor-aliases" "-funwind-tables=2" "-target-cpu" "ivybridge" "-target-feature" "-prfchw" "-target-feature" "-cldemote" "-target-feature" "+avx" "-target-feature" "+aes" "-target-feature" "+sahf" "-target-feature" "+pclmul" "-target-feature" "-xop" "-target-feature" "+crc32" "-target-feature" "-amx-fp8" "-target-feature" "-xsaves" "-target-feature" "-avx512fp16" "-target-feature" "-usermsr" "-target-feature" "-sm4" "-target-feature" "-egpr" "-target-feature" "+sse4.1" "-target-feature" "-avx512ifma" "-target-feature" "+xsave" "-target-feature" "+sse4.2" "-target-feature" "-tsxldtrk" "-target-feature" "-sm3" "-target-feature" "-ptwrite" "-target-feature" "-widekl" "-target-feature" "-movrs" "-target-feature" "-invpcid" "-target-feature" "+64bit" "-target-feature" "-xsavec" "-target-feature" "-avx10.1-512" "-target-feature" "-avx512vpopcntdq" "-target-feature" "+cmov" "-target-feature" "-avx512vp2intersect" "-target-feature" "-avx512cd" "-target-feature" "-movbe" "-target-feature" "-avxvnniint8" "-target-feature" "-ccmp" "-target-feature" "-amx-int8" "-target-feature" "-kl" "-target-feature" "-avx10.1-256" "-target-feature" "-sha512" "-target-feature" "-avxvnni" "-target-feature" "-rtm" "-target-feature" "-adx" "-target-feature" "-avx2" "-target-feature" "-hreset" "-target-feature" "-movdiri" "-target-feature" "-serialize" "-target-feature" "-vpclmulqdq" "-target-feature" "-avx512vl" "-target-feature" "-uintr" "-target-feature" "-cf" "-target-feature" "-clflushopt" "-target-feature" "-raoint" "-target-feature" "-cmpccxadd" "-target-feature" "-bmi" "-target-feature" "-amx-tile" "-target-feature" "+sse" "-target-feature" "-avx10.2-256" "-target-feature" "-gfni" "-target-feature" "-avxvnniint16" "-target-feature" "-amx-fp16" "-target-feature" "-zu" "-target-feature" "-ndd" "-target-feature" "+xsaveopt" "-target-feature" "+rdrnd" "-target-feature" "-avx512f" "-target-feature" "-amx-bf16" "-target-feature" "-avx512bf16" "-target-feature" "-avx512vnni" "-target-feature" "-push2pop2" "-target-feature" "+cx8" "-target-feature" "-avx512bw" "-target-feature" "+sse3" "-target-feature" "-pku" "-target-feature" "-nf" "-target-feature" "-amx-tf32" "-target-feature" "-amx-avx512" "-target-feature" "+fsgsbase" "-target-feature" "-clzero" "-target-feature" "-mwaitx" "-target-feature" "-lwp" "-target-feature" "-lzcnt" "-target-feature" "-sha" "-target-feature" "-movdir64b" "-target-feature" "-ppx" "-target-feature" "-wbnoinvd" "-target-feature" "-enqcmd" "-target-feature" "-amx-transpose" "-target-feature" "-avx10.2-512" "-target-feature" "-avxneconvert" "-target-feature" "-tbm" "-target-feature" "-pconfig" "-target-feature" "-amx-complex" "-target-feature" "+ssse3" "-target-feature" "+cx16" "-target-feature" "-bmi2" "-target-feature" "-fma" "-target-feature" "+popcnt" "-target-feature" "-avxifma" "-target-feature" "+f16c" "-target-feature" "-avx512bitalg" "-target-feature" "-rdpru" "-target-feature" "-clwb" "-target-feature" "+mmx" "-target-feature" "+sse2" "-target-feature" "-rdseed" "-target-feature" "-avx512vbmi2" "-target-feature" "-prefetchi" "-target-feature" "-amx-movrs" "-target-feature" "-rdpid" "-target-feature" "-fma4" "-target-feature" "-avx512vbmi" "-target-feature" "-shstk" "-target-feature" "-vaes" "-target-feature" "-waitpkg" "-target-feature" "-sgx" "-target-feature" "+fxsr" "-target-feature" "-avx512dq" "-target-feature" "-sse4a" "-debugger-tuning=gdb" "-fdebug-compilation-dir=/home/usr00/_rust/guessing_game" "-fcoverage-compilation-dir=/home/usr00/_rust/guessing_game" "-resource-dir" "/usr/lib/llvm-21/lib/clang/21" "-internal-isystem" "/usr/lib/llvm-21/lib/clang/21/include" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-ferror-limit" "19" "-fmessage-length=120" "-fgnuc-version=4.2.1" "-fskip-odr-check-in-gmf" "-fcolor-diagnostics" "-faddrsig" "-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o" "-" "-x" "c" "-"

gcc -Q -march=native --help=target | grep -v "\[disabled\]"

The following options are target specific:
 -m128bit-long-double [enabled]
 -m64 [enabled]
 -m80387 [enabled]
 -mabi= sysv
 -maddress-mode= long
 -maes [enabled]
 -malign-data= compat
 -malign-functions= 0
 -malign-jumps= 0
 -malign-loops= 0
 -malign-stringops [enabled]
 -mapx-features= none
 -march= ivybridge
 -masm= att
 -mavx [enabled]
 -mavx10.1 -mavx10.1-256
 -mavx256-split-unaligned-load [enabled]
 -mavx256-split-unaligned-store [enabled]
 -mbranch-cost=<0,5> 3
 -mcmodel= [default]
 -mcpu=
 -mcrc32 [enabled]
 -mcx16 [enabled]
 -mdirect-extern-access [enabled]
 -mf16c [enabled]
 -mfancy-math-387 [enabled]
 -mfentry-name=
 -mfentry-section=
 -mfp-ret-in-387 [enabled]
 -mfpmath= sse
 -mfsgsbase [enabled]
 -mfunction-return= keep
 -mfused-madd -ffp-contract=fast
 -mfxsr [enabled]
 -mgather -mtune-ctrl=use_gather
 -mglibc [enabled]
 -mhard-float [enabled]
 -mharden-sls= none
 -mieee-fp [enabled]
 -mincoming-stack-boundary= 0
 -mindirect-branch= keep
 -minstrument-return= none
 -mintel-syntax -masm=intel
 -mlam= none
 -mlarge-data-threshold=<number> 65536
 -mlong-double-80 [enabled]
 -mmemcpy-strategy=
 -mmemset-strategy=
 -mmmx [enabled]
 -mmove-max= 256
 -mmwait [enabled]
 -mpartial-vector-fp-math [enabled]
 -mpclmul [enabled]
 -mpopcnt [enabled]
 -mprefer-avx128 -mprefer-vector-width=128
 -mprefer-vector-width= none
 -mpreferred-stack-boundary= 0
 -mpush-args [enabled]
 -mrdrnd [enabled]
 -mrecip=
 -mred-zone [enabled]
 -mregparm= 6
 -msahf [enabled]
 -mscatter -mtune-ctrl=use_scatter
 -msse [enabled]
 -msse2 [enabled]
 -msse3 [enabled]
 -msse4 [enabled]
 -msse4.1 [enabled]
 -msse4.2 [enabled]
 -msse5 -mavx
 -mssse3 [enabled]
 -mstack-protector-guard-offset=
 -mstack-protector-guard-reg=
 -mstack-protector-guard-symbol=
 -mstack-protector-guard= tls
 -mstore-max= 256
 -mstringop-strategy= [default]
 -mstv [enabled]
 -mtls-dialect= gnu
 -mtls-direct-seg-refs [enabled]
 -mtune-ctrl=
 -mtune= ivybridge
 -mveclibabi= [default]
 -mxsave [enabled]
 -mxsaveopt [enabled]

 Known assembler dialects (for use with the -masm= option):
 att intel

 Known ABIs (for use with the -mabi= option):
 ms sysv

 Known code models (for use with the -mcmodel= option):
 32 kernel large medium small

 Valid arguments to -mfpmath=:
 387 387+sse 387,sse both sse sse+387 sse,387

 Known choices for mitigation against straight line speculation with -mharden-sls=:
 all indirect-jmp none return

 Known indirect branch choices (for use with the -mindirect-branch=/-mfunction-return= options):
 keep thunk thunk-extern thunk-inline

 Known choices for return instrumentation with -minstrument-return=:
 call none nop5

 Known data alignment choices (for use with the -malign-data= option):
 abi cacheline compat

 Known vectorization library ABIs (for use with the -mveclibabi= option):
 acml svml

 Known address mode (for use with the -maddress-mode= option):
 long short

 Known preferred register vector length (to use with the -mprefer-vector-width= option):
 128 256 512 none

 Known stack protector guard (for use with the -mstack-protector-guard= option):
 global tls

 Valid arguments to -mstringop-strategy=:
 byte_loop libcall loop rep_4byte rep_8byte rep_byte unrolled_loop vector_loop

 Known TLS dialects (for use with the -mtls-dialect= option):
 gnu gnu2

 Known valid arguments for -march= option:
 i386 i486 i586 pentium lakemont pentium-mmx winchip-c6 winchip2 c3 samuel-2 c3-2 nehemiah c7 esther i686 pentiumpro pentium2 pentium3 pentium3m pentium-m pentium4 pentium4m prescott nocona core2 nehalem corei7 westmere sandybridge corei7-avx ivybridge core-avx-i haswell core-avx2 broadwell skylake skylake-avx512 cannonlake icelake-client rocketlake icelake-server cascadelake tigerlake cooperlake sapphirerapids emeraldrapids alderlake raptorlake meteorlake graniterapids graniterapids-d arrowlake arrowlake-s lunarlake pantherlake bonnell atom silvermont slm goldmont goldmont-plus tremont gracemont sierraforest grandridge clearwaterforest knl knm intel geode k6 k6-2 k6-3 athlon athlon-tbird athlon-4 athlon-xp athlon-mp x86-64 x86-64-v2 x86-64-v3 x86-64-v4 eden-x2 nano nano-1000 nano-2000 nano-3000 nano-x2 eden-x4 nano-x4 lujiazui yongfeng k8 k8-sse3 opteron opteron-sse3 athlon64 athlon64-sse3 athlon-fx amdfam10 barcelona bdver1 bdver2 bdver3 bdver4 znver1 znver2 znver3 znver4 znver5 btver1 btver2 generic native

 Known valid arguments for -mtune= option:
 generic i386 i486 pentium lakemont pentiumpro pentium4 nocona core2 nehalem sandybridge haswell bonnell silvermont goldmont goldmont-plus tremont sierraforest grandridge clearwaterforest knl knm skylake skylake-avx512 cannonlake icelake-client icelake-server cascadelake tigerlake cooperlake sapphirerapids alderlake rocketlake graniterapids graniterapids-d arrowlake arrowlake-s pantherlake intel lujiazui yongfeng geode k6 athlon k8 amdfam10 bdver1 bdver2 bdver3 bdver4 btver1 btver2 znver1 znver2 znver3 znver4 znver5

[vstinner]

The following dependencies are missing from the script:

apt install wget clang lld pkg-config

[ppigazzini]

apt install wget clang lld pkg-config

That is only a snippet of a script that I use once to setup a development environment (pyenv, uv, nvm etc.) in a clean machine/vm.

I install clang versions from llvm with this script:

click to view

#!/bin/bash
# 251010
# add clang ${version} to Ubuntu

update_alternatives() {
 local version=${1}
 local priority=${2}
 local master=${3}
 local slaves=${4}
 local path=${5}
 local cmdln

 cmdln="--verbose --install ${path}${master} ${master} ${path}${master}-${version} ${priority}"
 for slave in ${slaves}; do
 cmdln="${cmdln} --slave ${path}${slave} ${slave} ${path}${slave}-${version}"
 done
 sudo update-alternatives ${cmdln}
}


if [[ ${#} -ne 2 ]]; then
 echo usage: "${0}" clang_version priority
 exit 1
fi

version=${1}
priority=${2}
path="/usr/bin/"

sudo apt update

# download and launch the setup script
curl -sSL https://apt.llvm.org/llvm.sh | sudo bash -s ${version}
# sudo apt install -y bolt-${version}
# curl -sSL https://apt.llvm.org/llvm.sh | sudo bash -s ${version} all

# configure with update-alternatives
master="llvm-config"
# v19
#slaves="asan_symbolize bugpoint clang++ clang clang-cpp clangd count dsymutil FileCheck ld64.lld ld.lld llc lld lldb lldb-argdumper lldb-dap lldb-instr lldb-server lld-link lli lli-child-target llvm-addr2line llvm-ar llvm-as llvm-bcanalyzer llvm-bitcode-strip llvm-cat llvm-cfi-verify llvm-cov llvm-c-test llvm-cvtres llvm-cxxdump llvm-cxxfilt llvm-cxxmap llvm-debuginfo-analyzer llvm-debuginfod llvm-debuginfod-find llvm-diff llvm-dis llvm-dlltool llvm-dwarfdump llvm-dwarfutil llvm-dwp llvm-exegesis llvm-extract llvm-gsymutil llvm-ifs llvm-install-name-tool llvm-jitlink llvm-jitlink-executor llvm-lib llvm-libtool-darwin llvm-link llvm-lipo llvm-lto llvm-lto2 llvm-mc llvm-mca llvm-ml llvm-modextract llvm-mt llvm-nm llvm-objcopy llvm-objdump llvm-opt-report llvm-otool llvm-pdbutil llvm-PerfectShuffle llvm-profdata llvm-profgen llvm-ranlib llvm-rc llvm-readelf llvm-readobj llvm-readtapi llvm-reduce llvm-remarkutil llvm-rtdyld llvm-sim llvm-size llvm-split llvm-stress llvm-strings llvm-strip llvm-symbolizer llvm-tblgen llvm-tli-checker llvm-undname llvm-windres llvm-xray not obj2yaml opt reduce-chunk-list sanstats split-file UnicodeNameMappingGenerator verify-uselistorder wasm-ld yaml2obj yaml-bench"
# v19 with bolt
#slaves="amdgpu-arch analyze-build asan_symbolize bugpoint c-index-test clang++ clang clang-apply-replacements clang-change-namespace clang-check clang-cl clang-cpp clangd clang-doc clang-extdef-mapping clang-include-cleaner clang-include-fixer clang-installapi clang-linker-wrapper clang-move clang-nvlink-wrapper clang-offload-bundler clang-offload-packager clang-pseudo clang-query clang-refactor clang-rename clang-reorder-fields clang-repl clang-scan-deps clang-tblgen count diagtool dsymutil FileCheck find-all-symbols hmaptool hwasan_symbolize intercept-build ld64.lld ld.lld llc lld lldb lldb-argdumper lldb-dap lldb-instr lldb-server lld-link lli lli-child-target llvm-addr2line llvm-ar llvm-as llvm-bcanalyzer llvm-bitcode-strip llvm-bolt llvm-boltdiff llvm-bolt-heatmap llvm-cat llvm-cfi-verify llvm-cov llvm-c-test llvm-cvtres llvm-cxxdump llvm-cxxfilt llvm-cxxmap llvm-debuginfo-analyzer llvm-debuginfod llvm-debuginfod-find llvm-diff llvm-dis llvm-dlltool llvm-dwarfdump llvm-dwarfutil llvm-dwp llvm-exegesis llvm-extract llvm-gsymutil llvm-ifs llvm-install-name-tool llvm-jitlink llvm-jitlink-executor llvm-lib llvm-libtool-darwin llvm-link llvm-lipo llvm-lto llvm-lto2 llvm-mc llvm-mca llvm-ml llvm-modextract llvm-mt llvm-nm llvm-objcopy llvm-objdump llvm-opt-report llvm-otool llvm-pdbutil llvm-PerfectShuffle llvm-profdata llvm-profgen llvm-ranlib llvm-rc llvm-readelf llvm-readobj llvm-readtapi llvm-reduce llvm-remarkutil llvm-rtdyld llvm-sim llvm-size llvm-split llvm-stress llvm-strings llvm-strip llvm-symbolizer llvm-tblgen llvm-tli-checker llvm-undname llvm-windres llvm-xray merge-fdata modularize not nvptx-arch obj2yaml opt perf2bolt pp-trace reduce-chunk-list sancov sanstats scan-build scan-build-py scan-view split-file UnicodeNameMappingGenerator verify-uselistorder wasm-ld yaml2obj yaml-bench"
# v20
#slaves="amdgpu-arch analyze-build asan_symbolize bugpoint c-index-test clang++ clang clang-apply-replacements clang-change-namespace clang-check clang-cl clang-cpp clangd clang-doc clang-extdef-mapping clang-include-cleaner clang-include-fixer clang-installapi clang-linker-wrapper clang-move clang-nvlink-wrapper clang-offload-bundler clang-offload-packager clang-query clang-refactor clang-reorder-fields clang-repl clang-scan-deps clang-sycl-linker clang-tblgen count diagtool dsymutil FileCheck find-all-symbols hmaptool hwasan_symbolize intercept-build ld64.lld ld.lld llc lld lldb lldb-argdumper lldb-dap lldb-instr lldb-server lld-link lli lli-child-target llvm-addr2line llvm-ar llvm-as llvm-bcanalyzer llvm-bitcode-strip llvm-cat llvm-cfi-verify llvm-cgdata llvm-cov llvm-c-test llvm-ctxprof-util llvm-cvtres llvm-cxxdump llvm-cxxfilt llvm-cxxmap llvm-debuginfo-analyzer llvm-debuginfod llvm-debuginfod-find llvm-diff llvm-dis llvm-dlltool llvm-dwarfdump llvm-dwarfutil llvm-dwp llvm-exegesis llvm-extract llvm-gsymutil llvm-ifs llvm-install-name-tool llvm-jitlink llvm-jitlink-executor llvm-lib llvm-libtool-darwin llvm-link llvm-lipo llvm-lto llvm-lto2 llvm-mc llvm-mca llvm-ml llvm-modextract llvm-mt llvm-nm llvm-objcopy llvm-objdump llvm-opt-report llvm-otool llvm-pdbutil llvm-PerfectShuffle llvm-profdata llvm-profgen llvm-ranlib llvm-rc llvm-readelf llvm-readobj llvm-readtapi llvm-reduce llvm-remarkutil llvm-rtdyld llvm-sim llvm-size llvm-split llvm-stress llvm-strings llvm-strip llvm-symbolizer llvm-tblgen llvm-tli-checker llvm-undname llvm-windres llvm-xray modularize not nvptx-arch obj2yaml opt pp-trace reduce-chunk-list sancov sanstats scan-build scan-build-py scan-view split-file UnicodeNameMappingGenerator verify-uselistorder wasm-ld yaml2obj yaml-bench"
# v20 with bolt
#slaves="amdgpu-arch analyze-build asan_symbolize bugpoint c-index-test clang++ clang clang-apply-replacements clang-change-namespace clang-check clang-cl clang-cpp clangd clang-doc clang-extdef-mapping clang-include-cleaner clang-include-fixer clang-installapi clang-linker-wrapper clang-move clang-nvlink-wrapper clang-offload-bundler clang-offload-packager clang-query clang-refactor clang-reorder-fields clang-repl clang-scan-deps clang-sycl-linker clang-tblgen count diagtool dsymutil FileCheck find-all-symbols hmaptool hwasan_symbolize intercept-build ld64.lld ld.lld llc lld lldb lldb-argdumper lldb-dap lldb-instr lldb-server lld-link lli lli-child-target llvm-addr2line llvm-ar llvm-as llvm-bcanalyzer llvm-bitcode-strip llvm-bolt llvm-bolt-binary-analysis llvm-boltdiff llvm-bolt-heatmap llvm-cat llvm-cfi-verify llvm-cgdata llvm-cov llvm-c-test llvm-ctxprof-util llvm-cvtres llvm-cxxdump llvm-cxxfilt llvm-cxxmap llvm-debuginfo-analyzer llvm-debuginfod llvm-debuginfod-find llvm-diff llvm-dis llvm-dlltool llvm-dwarfdump llvm-dwarfutil llvm-dwp llvm-exegesis llvm-extract llvm-gsymutil llvm-ifs llvm-install-name-tool llvm-jitlink llvm-jitlink-executor llvm-lib llvm-libtool-darwin llvm-link llvm-lipo llvm-lto llvm-lto2 llvm-mc llvm-mca llvm-ml llvm-modextract llvm-mt llvm-nm llvm-objcopy llvm-objdump llvm-opt-report llvm-otool llvm-pdbutil llvm-PerfectShuffle llvm-profdata llvm-profgen llvm-ranlib llvm-rc llvm-readelf llvm-readobj llvm-readtapi llvm-reduce llvm-remarkutil llvm-rtdyld llvm-sim llvm-size llvm-split llvm-stress llvm-strings llvm-strip llvm-symbolizer llvm-tblgen llvm-tli-checker llvm-undname llvm-windres llvm-xray merge-fdata modularize not nvptx-arch obj2yaml opt perf2bolt pp-trace reduce-chunk-list sancov sanstats scan-build scan-build-py scan-view split-file UnicodeNameMappingGenerator verify-uselistorder wasm-ld yaml2obj yaml-bench"
# v21
slaves="amdgpu-arch analyze-build asan_symbolize bugpoint c-index-test clang++ clang clang-apply-replacements clang-change-namespace clang-check clang-cl clang-cpp clangd clang-doc clang-extdef-mapping clang-include-cleaner clang-include-fixer clang-installapi clang-linker-wrapper clang-move clang-nvlink-wrapper clang-offload-bundler clang-offload-packager clang-query clang-refactor clang-reorder-fields clang-repl clang-scan-deps clang-sycl-linker clang-tblgen count diagtool dsymutil FileCheck find-all-symbols hmaptool hwasan_symbolize intercept-build ld64.lld ld.lld llc lld lldb lldb-argdumper lldb-dap lldb-instr lldb-server lld-link lli lli-child-target llvm-addr2line llvm-ar llvm-as llvm-bcanalyzer llvm-bitcode-strip llvm-cat llvm-cfi-verify llvm-cgdata llvm-cov llvm-c-test llvm-ctxprof-util llvm-cvtres llvm-cxxdump llvm-cxxfilt llvm-cxxmap llvm-debuginfo-analyzer llvm-debuginfod llvm-debuginfod-find llvm-diff llvm-dis llvm-dlltool llvm-dwarfdump llvm-dwarfutil llvm-dwp llvm-exegesis llvm-extract llvm-gsymutil llvm-ifs llvm-install-name-tool llvm-jitlink llvm-jitlink-executor llvm-lib llvm-libtool-darwin llvm-link llvm-lipo llvm-lto llvm-lto2 llvm-mc llvm-mca llvm-ml llvm-ml64 llvm-modextract llvm-mt llvm-nm llvm-objcopy llvm-objdump llvm-opt-report llvm-otool llvm-pdbutil llvm-PerfectShuffle llvm-profdata llvm-profgen llvm-ranlib llvm-rc llvm-readelf llvm-readobj llvm-readtapi llvm-reduce llvm-remarkutil llvm-rtdyld llvm-sim llvm-size llvm-split llvm-stress llvm-strings llvm-strip llvm-symbolizer llvm-tblgen llvm-test-mustache-spec llvm-tli-checker llvm-undname llvm-windres llvm-xray modularize not nvptx-arch obj2yaml offload-arch opt pp-trace reduce-chunk-list sancov sanstats scan-build scan-build-py scan-view split-file UnicodeNameMappingGenerator verify-uselistorder wasm-ld yaml2obj yaml-bench"
# v21 with bolt
#slaves="amdgpu-arch analyze-build asan_symbolize bugpoint c-index-test clang++ clang clang-apply-replacements clang-change-namespace clang-check clang-cl clang-cpp clangd clang-doc clang-extdef-mapping clang-include-cleaner clang-include-fixer clang-installapi clang-linker-wrapper clang-move clang-nvlink-wrapper clang-offload-bundler clang-offload-packager clang-query clang-refactor clang-reorder-fields clang-repl clang-scan-deps clang-sycl-linker clang-tblgen count diagtool dsymutil FileCheck find-all-symbols hmaptool hwasan_symbolize intercept-build ld64.lld ld.lld llc lld lldb lldb-argdumper lldb-dap lldb-instr lldb-server lld-link lli lli-child-target llvm-addr2line llvm-ar llvm-as llvm-bcanalyzer llvm-bitcode-strip llvm-bolt llvm-bolt-binary-analysis llvm-boltdiff llvm-bolt-heatmap llvm-cat llvm-cfi-verify llvm-cgdata llvm-cov llvm-c-test llvm-ctxprof-util llvm-cvtres llvm-cxxdump llvm-cxxfilt llvm-cxxmap llvm-debuginfo-analyzer llvm-debuginfod llvm-debuginfod-find llvm-diff llvm-dis llvm-dlltool llvm-dwarfdump llvm-dwarfutil llvm-dwp llvm-exegesis llvm-extract llvm-gsymutil llvm-ifs llvm-install-name-tool llvm-jitlink llvm-jitlink-executor llvm-lib llvm-libtool-darwin llvm-link llvm-lipo llvm-lto llvm-lto2 llvm-mc llvm-mca llvm-ml llvm-ml64 llvm-modextract llvm-mt llvm-nm llvm-objcopy llvm-objdump llvm-opt-report llvm-otool llvm-pdbutil llvm-PerfectShuffle llvm-profdata llvm-profgen llvm-ranlib llvm-rc llvm-readelf llvm-readobj llvm-readtapi llvm-reduce llvm-remarkutil llvm-rtdyld llvm-sim llvm-size llvm-split llvm-stress llvm-strings llvm-strip llvm-symbolizer llvm-tblgen llvm-test-mustache-spec llvm-tli-checker llvm-undname llvm-windres llvm-xray merge-fdata modularize not nvptx-arch obj2yaml offload-arch opt perf2bolt pp-trace reduce-chunk-list sancov sanstats scan-build scan-build-py scan-view split-file UnicodeNameMappingGenerator verify-uselistorder wasm-ld yaml2obj yaml-bench"

update_alternatives "${version}" "${priority}" "${master}" "${slaves}" "${path}"

exit

# to uninstall a Clang version
LLVM_VERSION=20
sudo apt purge -y clang-${LLVM_VERSION} lldb-${LLVM_VERSION} lld-${LLVM_VERSION} clangd-${LLVM_VERSION} bolt-${LLVM_VERSION} && sudo apt autoremove -y
sudo update-alternatives --config llvm-config

# to generate the list of slaves on a clean Ubuntu vm
sudo apt update && sudo apt full-upgrade -y && sudo apt autoremove -y && sudo apt autoclean
ls /usr/bin > usr_bin_orig
version=21
curl -sSL https://apt.llvm.org/llvm.sh | sudo bash -s "$version"
# sudo apt install -y bolt-$version
# curl -sSL https://apt.llvm.org/llvm.sh | sudo bash -s "$version" all
ls /usr/bin > usr_bin_new
diff usr_bin_new usr_bin_orig | awk -v ver="$version" '/^< / && !/llvm-config-'"$version"'$/ && /-'"$version"'$/ {gsub("^< ",""); gsub("-" ver "$",""); printf "%s ", $0} END {print ""}' > slaves_llvm
# check if an application is already a master in:
# /var/lib/dpkg/alternatives/

[vstinner]

I failed to reproduce the issue. The pyenv command succeeded with: Installed Python-3.14.2 to /root/.pyenv/versions/3.14.2. The build logs contain 0:01:19 load avg: 3.04 [39/43] test_struct passed.

I ran the commands in a Ubuntu 24.04 container (clang 18.1.3). On my (Fedora) Linux host, /proc/cpuinfo says Intel(R) Core(TM) i7-10850H CPU @ 2.70GHz.

Tested on Ubuntu 24.04 (gcc 14.2.0 - clang 21.1.8) and Ubuntu 20.04 (gcc 11.4.0), several CPUs.

How did you get clang 21 on Ubuntu 24.04? apt only installed clang 18.1.3 for me.

[ppigazzini]

Cross posting, check the script in my previous post to setup clang 21 on Ubuntu.
BTW pyenv builds python 3.14.2 without issues with either clang/gcc, but test_struct fails in python3 -m test with gcc/clang with that traceback.

EDIT: python -m test test_struct runs only the "bad" test.

[ppigazzini]

I built python 3.14.2 in a clean VM Ubuntu 24.04, using default gcc 13.3.0, with this script.

click to view

#!/bin/bash

python_ver=3.14.2

# setup pyenv and install latest python
# https://github.com/pyenv/pyenv
# https://github.com/python/pyperformance

# dependencies according to pyenv
#sudo apt update; sudo apt install -y build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev

# Workaround missing libmpdec-dev on ubuntu 24.04 (it should be re introduced in ubuntu 26.04):
# https://launchpad.net/~ondrej/+archive/ubuntu/php
# https://deb.sury.org/
sudo add-apt-repository -y ppa:ondrej/php

# dependencies according to python build doc dropping packages used in CI (ccache, cmake, gdb, inetutils-inetd, lcov, lzma, strace, xvfb)
# https://devguide.python.org/getting-started/setup-building/index.html#build-dependencies
# https://github.com/python/cpython/blob/main/.github/workflows/posix-deps-apt.sh
sudo apt update; sudo apt install -y build-essential pkg-config libb2-dev libbz2-dev libffi-dev libgdbm-dev libgdbm-compat-dev liblzma-dev libncurses5-dev libreadline6-dev libsqlite3-dev libssl-dev lzma-dev tk-dev uuid-dev zlib1g-dev libzstd-dev libmpdec-dev

pyenv_dir="$HOME/.pyenv"
git clone https://github.com/pyenv/pyenv.git "$pyenv_dir"

cat << 'EOF' >> "$HOME/.profile"

# pyenv: keep at the end of the file
export PYENV_ROOT="$HOME/.pyenv"
command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -)"
EOF

cat << 'EOF' >> "$HOME/.bashrc"

# pyenv: keep at the end of the file
export PYENV_ROOT="$HOME/.pyenv"
command -v pyenv >/dev/null || export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -)"
EOF

. "$HOME/.profile"
pushd "$pyenv_dir" && src/configure && make -C src && popd
PYTHON_CONFIGURE_OPTS="--enable-optimizations --with-lto" PYTHON_CFLAGS="-march=native -mtune=native" pyenv install "$python_ver"

pyenv global "$python_ver"
python3 -m test

Running python3 -m test fails for test_struct

Running python3 -m test test_struct succeed.

I wonder if test_struct finds some leftovers from previous tests...

Downloading Python-3.14.2.tar.xz...
-> https://www.python.org/ftp/python/3.14.2/Python-3.14.2.tar.xz
Installing Python-3.14.2...
Installed Python-3.14.2 to /home/vmuser/.pyenv/versions/3.14.2
Using random seed: 2266171211
0:00:00 load avg: 0.06 Run 491 tests sequentially in a single process
0:00:00 load avg: 0.06 [ 1/491] test.test_asyncio.test_base_events
0:00:01 load avg: 0.14 [ 1/491] test.test_asyncio.test_base_events passed
0:00:01 load avg: 0.14 [ 2/491] test.test_asyncio.test_buffered_proto

...

0:20:19 load avg: 1.96 [490/491/1] test_zoneinfo passed
0:20:19 load avg: 1.96 [491/491/1] test_zstd
0:20:20 load avg: 1.96 [491/491/1] test_zstd passed

== Tests result: FAILURE ==

22 tests skipped:
 test.test_asyncio.test_windows_events
 test.test_asyncio.test_windows_utils test.test_gdb.test_backtrace
 test.test_gdb.test_cfunction test.test_gdb.test_cfunction_full
 test.test_gdb.test_misc test.test_gdb.test_pretty_print
 test_android test_apple test_asdl_parser test_clinic test_devpoll
 test_free_threading test_generated_cases test_kqueue test_launcher
 test_msvcrt test_startfile test_winapi test_winconsoleio
 test_winreg test_wmi

10 tests skipped (resource denied):
 test_curses test_peg_generator test_smtpnet test_socketserver
 test_tkinter test_ttk test_urllib2net test_urllibnet test_winsound
 test_zipfile64

1 test failed:
 test_struct

458 tests OK.

Total duration: 20 min 20 sec
Total tests: run=46,881 skipped=2,243
Total test files: run=481/491 failed=1 skipped=22 resource_denied=10
Result: FAILURE

vmuser@u2404:~$ python3 -m test test_struct
Using random seed: 847363914
0:00:00 load avg: 0.00 Run 1 test sequentially in a single process
0:00:00 load avg: 0.00 [1/1] test_struct
0:00:00 load avg: 0.00 [1/1] test_struct passed

== Tests result: SUCCESS ==

1 test OK.

Total duration: 447 ms
Total tests: run=41
Total test files: run=1/1
Result: SUCCESS

[ppigazzini]

I found the culprit pair of tests.
python3 -m test test_interpreters test_struct

click to view

vmuser@u2404:~$ python3 -m test test_interpreters test_struct
Using random seed: 2256134008
0:00:00 load avg: 0.07 Run 2 tests sequentially in a single process
0:00:00 load avg: 0.07 [1/2] test_interpreters
0:00:09 load avg: 0.21 [1/2] test_interpreters passed
0:00:09 load avg: 0.21 [2/2] test_struct
Exception in initializer:
Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
Exception in initializer:
Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 88, in serialize_unbound
 flag = _UNBOUND_CONSTANT_TO_FLAG[op]
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^
KeyError: concurrent.interpreters._queues.UNBOUND

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/thread.py", line 99, in _worker
 ctx.initialize()
 ~~~~~~~~~~~~~~^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/interpreter.py", line 64, in initialize
 self.results = interpreters.create_queue(maxsize)
 ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 75, in create
 unbound = _serialize_unbound(unbounditems)
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_queues.py", line 56, in _serialize_unbound
 return _crossinterp.serialize_unbound(unbound)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/interpreters/_crossinterp.py", line 90, in serialize_unbound
 raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
NotImplementedError: unsupported unbound replacement op concurrent.interpreters._queues.UNBOUND
test test_struct failed -- Traceback (most recent call last):
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/test/test_struct.py", line 818, in test_endian_table_init_subinterpreters
 self.assertListEqual(list(results), [None] * 5)
 ~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 639, in result_iterator
 yield _result_or_cancel(fs.pop())
 ~~~~~~~~~~~~~~~~~^^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 311, in _result_or_cancel
 return fut.result(timeout)
 ~~~~~~~~~~^^^^^^^^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 450, in result
 return self.__get_result()
 ~~~~~~~~~~~~~~~~~^^
 File "/home/vmuser/.pyenv/versions/3.14.2/lib/python3.14/concurrent/futures/_base.py", line 395, in __get_result
 raise self._exception
concurrent.futures.interpreter.BrokenInterpreterPool: A thread initializer failed, the thread pool is not usable anymore

0:00:09 load avg: 0.21 [2/2/1] test_struct failed (1 error)

== Tests result: FAILURE ==

1 test failed:
 test_struct

1 test OK.

Total duration: 9.6 sec
Total tests: run=211 skipped=8
Total test files: run=2/2 failed=1
Result: FAILURE

For whatever reason crossinterp tries to serialize the UNBOUND sentinel from queue

cpython/Lib/concurrent/interpreters/_crossinterp.py

Lines 72 to 91 in 7f497c3

	UNBOUND = object.__new__(UnboundItem)
	UNBOUND_ERROR = object()
	UNBOUND_REMOVE = object()
	_UNBOUND_CONSTANT_TO_FLAG = {
	UNBOUND_REMOVE: 1,
	UNBOUND_ERROR: 2,
	UNBOUND: 3,
	}
	_UNBOUND_FLAG_TO_CONSTANT = {v: k
	for k, v in _UNBOUND_CONSTANT_TO_FLAG.items()}
	def serialize_unbound(unbound):
	op = unbound
	try:
	flag = _UNBOUND_CONSTANT_TO_FLAG[op]
	except KeyError:
	raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
	return flag,

[ppigazzini]

Script for any recent Ubuntu, to build official python 3.14.2 with gcc, default options, and run the pairs of tests that exposes the bug. Tested working in a clean VM Ubuntu 22.04 - 24.04.

#!/usr/bin/env bash
set -euo pipefail

# ---- Config (overridable via env) ----
PYTHON_VER="${PYTHON_VER:-3.14.2}"
PREFIX="${PREFIX:-$HOME/.local/python-${PYTHON_VER}}"
WORKDIR="${WORKDIR:-$HOME/build-python-${PYTHON_VER}}"
JOBS="${JOBS:-$(nproc)}"
INSTALL_DEPS="${INSTALL_DEPS:-1}" # set to 0 to skip apt

TAR="Python-${PYTHON_VER}.tar.xz"
URL="https://www.python.org/ftp/python/${PYTHON_VER}/${TAR}"

# ---- Functions ----
detect_ubuntu_2404() {
 if [[ -r /etc/os-release ]]; then
 # shellcheck disable=SC1091
 . /etc/os-release
 [[ "${ID:-}" == "ubuntu" && "${VERSION_ID:-}" == "24.04" ]]
 else
 return 1
 fi
}

install_deps() {
 [[ "${INSTALL_DEPS}" -eq 1 ]] || { echo "Skipping apt dependencies."; return 0; }

 echo "Installing build dependencies (requires sudo)..."
 if detect_ubuntu_2404; then
 echo "Detected Ubuntu 24.04 -> enabling ondrej/php PPA for libmpdec-dev"
 sudo add-apt-repository -y ppa:ondrej/php || true
 fi

 sudo apt update
 sudo apt install -y \
 build-essential pkg-config wget ca-certificates xz-utils \
 libssl-dev zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev \
 libncursesw5-dev libncurses5-dev libffi-dev liblzma-dev tk-dev \
 libgdbm-dev libgdbm-compat-dev uuid-dev libzstd-dev libmpdec-dev \
 libxml2-dev libxmlsec1-dev
}

build_python() {
 mkdir -p "${WORKDIR}"
 pushd "${WORKDIR}" >/dev/null

 if [[ ! -f "${TAR}" ]]; then
 echo "Downloading ${TAR}..."
 wget -c "${URL}"
 fi

 rm -rf "Python-${PYTHON_VER}"
 tar -xf "${TAR}"
 cd "Python-${PYTHON_VER}"

 echo "Configuring Python ${PYTHON_VER} with prefix ${PREFIX}"
 ./configure --prefix="${PREFIX}"

 echo "Building with make -j${JOBS}"
 make -j"${JOBS}"

 echo "Installing into ${PREFIX}"
 make install

 popd >/dev/null
}

run_smoke_tests() {
 local py="${PREFIX}/bin/python3"

 export PATH="${PREFIX}/bin:${PATH}"

 echo "Using interpreter: $(${py} -V)"
 echo "Running failing pair: test_interpreters + test_struct"
 "${py}" -m test test_interpreters test_struct
}

# ---- Main ----
echo "Building Python ${PYTHON_VER} into ${PREFIX}"
echo "Workdir: ${WORKDIR}"

install_deps
build_python
run_smoke_tests

[vstinner]

Correction: I am able to reproduce the test_struct failure when running python -m test: when the whole test suite is run sequentially.