Officially add Windows ARM64 to tier 1.5

As per the Tier 1.5 discussion in #10406 (and the open PR to add the definition into the docs in #10548), I'd like to propose we add Windows ARM64 to Tier 1.5 over the next few months.

Windows on ARM64 is becoming more popular, and we've seen several requests for native support:

Initially I think we should add just Python 3.14 support (no free-threading) as a test. I expect most bugs will be either related to word sizes or LLVM linker issues with MCJIT, so once we are happy with it, we can talk about expanding the support to more Python versions.

This was discussed during the maintainer meeting today and no objections to moving forward with this were raised:

https://hackmd.io/vYBWLcuZT7eYj4vDyCzZAw

Hi, just wanted to update this issue to note that we are actively working on this. I don't have a precise ETA yet, because we expect to discover if LLVM (especially MCJIT) has any yet-unknown Windows ARM64 bugs that impact Numba. We're hoping to have something building in GHA, even if not fully working, by the end of the month, and want to ship experimental packages hopefully around the time that Python 3.15 is released.

@seibert

Hi @seibert

Currently, there is one bug in llvmlite on windows ARM64 which is affecting the Unicodesets test cases in Numba. Kindly refer to the following trackers:

Fix invalid fixup errors on Windows ARM64: Fix invalid fixup errors on Windows ARM64 llvmlite#1427
JIT compilation fails with uimm12 fixup error for large UniTuple arguments: JIT compilation fails with uimm12 fixup error for large UniTuple arguments #10619

Thanks

@seibert

Hi @seibert,
Now that the PR fixing the Numba UnicodeSet test failures has been merged, could you share the ETA for the Windows ARM64 releases?

@MugundanMCW

Hi @seibert, Now that the PR fixing the Numba UnicodeSet test failures has been merged, could you share the ETA for the Windows ARM64 releases?

Hello @MugundanMCW,
Release candidates for llvmlite 0.49 and Numba 0.67 are currently being prepared. These releases will include numpy2.5 support and the first Windows ARM64 binaries, both conda packages and wheels.

@swap357

Thanks @swap357 for sharing the ETA

Windows-arm64 wheels are now available with Numba 0.67.0 and llvmlite 0.49.0
https://pypi.org/project/numba/0.67.0/#files
Please test and post any findings.

@swap357

sure @swap357, thanks

I have tried this with python 3.14 and 3.11 on both Windows and WSL, but unfortunately still have the same compilation error. Testing the minimal example from the docs:

from numba import jit
import numpy as np

x = np.arange(100).reshape(10, 10)

@jit
def go_fast(a):
    trace = 0.0
    for i in range(a.shape[0]):
        trace += np.tanh(a[i, i])
    return a + trace

print(go_fast(x))

gives

DefIdx 1 exceeds machine model writes for early-clobber %25:gpr64sp, %26:gpr64 = LDRXpost %4:gpr64sp(tied-def 0), 8 ::(load (s64) from %ir.lsr.iv9)
 (Try with MCSchedModel.CompleteModel set to false)incomplete machine model
UNREACHABLE executed at C:\a\_temp\conda-base\conda-bld\llvmdev_1782178184130\work\llvm\lib\CodeGen\TargetSchedule.cpp:226!

Numba was installed in a clean venv from the wheel.

numba -s from Windows with Python 3.14

__Time Stamp__
Report started (local time)                   : 2026-08-14 10:20:00.170197
UTC start time                                : 2026-08-14 08:20:00.170223
Running time (s)                              : 2.661254

__Hardware Information__
Machine                                       : ARM64
CPU Name                                      : oryon-1
CPU Count                                     : 12
Number of accessible CPUs                     : ?
List of accessible CPUs cores                 : ?
CFS Restrictions (CPUs worth of runtime)      : None

CPU Features                                  : aes bf16 crc dotprod fullfp16 i8mm
                                                jsconv lse rcpc sha2

Memory Total (MB)                             : 59973
Memory Available (MB)                         : 19395

__OS Information__
Platform Name                                 : Windows-11-10.0.26200-SP0
Platform Release                              : 11
OS Name                                       : Windows
OS Version                                    : 10.0.26200
OS Specific Version                           : 11 10.0.26200 SP0 Multiprocessor Free
Libc Version                                  : ?

__Python Information__
Python Compiler                               : MSC v.1944 64 bit (ARM64)
Python Implementation                         : CPython
Python Version                                : 3.14.4
Python Locale                                 : en_AU.cp1252

__Numba Toolchain Versions__
Numba Version                                 : 0.67.0
llvmlite Version                              : 0.49.0

__LLVM Information__
LLVM Version                                  : 22.1.0

__CUDA Information__
CUDA Target Implementation                    : Built-in
CUDA Device Initialized                       : False
CUDA Driver Version                           : ?
CUDA Runtime Version                          : ?
CUDA NVIDIA Bindings Available                : ?
CUDA NVIDIA Bindings In Use                   : ?
CUDA Minor Version Compatibility Available    : ?
CUDA Minor Version Compatibility Needed       : ?
CUDA Minor Version Compatibility In Use       : ?
CUDA Detect Output:
None
CUDA Libraries Test Output:
None

__NumPy Information__
NumPy Version                                 : 2.5.2
NumPy Supported SIMD features                 : ('NEON', 'NEON_FP16', 'NEON_VFPV4', 'ASIMD')
NumPy Supported SIMD dispatch                 : ('ASIMDHP', 'ASIMDDP', 'ASIMDFHM')
NumPy Supported SIMD baseline                 : ('NEON', 'NEON_FP16', 'NEON_VFPV4', 'ASIMD')

__SVML Information__
SVML State, config.USING_SVML                 : False
SVML Library Loaded                           : False
llvmlite Using SVML Patched LLVM              : False
SVML Operational                              : False

__Threading Layer Information__
TBB Threading Layer Available                 : False
+--> Disabled due to Unknown import problem.
OpenMP Threading Layer Available              : True
+-->Vendor: MS
Workqueue Threading Layer Available           : True
+-->Workqueue imported successfully.

__Numba Environment Variable Information__
None found.

__Conda Information__
Conda not available.

__Installed Packages__
Package  Version
-------- -------
llvmlite 0.49.0
numba    0.67.0
numpy    2.5.2
pip      26.2.1

No errors reported.


__Warning log__
Warning (cuda): CUDA driver library cannot be found or no CUDA enabled devices are present.
Exception class: <class 'numba.cuda.cudadrv.error.CudaSupportError'>
Warning: Conda not available.
Warning (psutil): psutil cannot be imported. For more accuracy, consider installing it.

@jasperlittle

Looks like another oryon-specific backend error in LLVM. @jasperlittle if you set the environment variable NUMBA_CPU_NAME="generic", does that work around the issue?

@gmarkall

@gmarkall yup, that works fine on both Windows and WSL

This might be same issue as #10388 and needs this suggested patch #10388 (comment) to llvmdev. I'm working to rebuild llvmdev for next release as part of manylinux image upgrade (numba/llvmlite#1471), can someone open a PR with that patch to llvmdev recipe ? I can review it.

@swap357

Yeah sure @swap357, let me create a PR with this patch

@seibert

@seibert I think with the availability of artifacts for win-arm64 and a mention in the docs:

Wheel packages on the PyPI distribution system and conda packages on the Anaconda dot org distribution system for Python 3.14 only. Support for additional Python versions may be added in the future.

    win-arm64 (Windows on 64-bit ARM)

This can be closed now? Artifacts are available, CI is setup, support is documented.

FYI: since more versions below 3.14 are no supported, here is a PR to update the docs:

#10805

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Officially add Windows ARM64 to tier 1.5 #10549

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Officially add Windows ARM64 to tier 1.5 #10549

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esc commented on Apr 21, 2026

seibert commented on Jun 10, 2026

MugundanMCW commented on Jun 10, 2026

MugundanMCW commented on Jul 22, 2026

swap357 commented on Jul 22, 2026

MugundanMCW commented on Jul 23, 2026

swap357 commented on Aug 12, 2026

MugundanMCW commented on Aug 12, 2026

jasperlittle commented on Aug 14, 2026

gmarkall commented on Aug 14, 2026

jasperlittle commented on Aug 14, 2026

swap357 commented on Aug 14, 2026

MugundanMCW commented on Aug 15, 2026

esc commented on Aug 28, 2026

esc commented on Aug 28, 2026

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