Minimal bug reproduction case in the interaction of ctypes.Union with llvmlite

llvmlite_ctypes_bug.py

"""
# These are the values I see on my system that reproduces the bug:

$ uname -a
Darwin silver-surfer.lan 21.3.0 Darwin Kernel Version 21.3.0: Wed Jan  5 21:37:58 PST 2022; root:xnu-8019.80.24~20/RELEASE_X86_64 x86_64

$ /usr/local/Cellar/llvm@11/11.1.0_4/bin/clang -v
Homebrew clang version 11.1.0
Target: x86_64-apple-darwin21.3.0
Thread model: posix
InstalledDir: /usr/local/Cellar/llvm@11/11.1.0_4/bin

$ python3 -c 'import sys; print(sys.version)'
3.9.10 (main, Jan 15 2022, 11:48:04)
[Clang 13.0.0 (clang-1300.0.29.3)]

$ cat requirements.txt
llvmlite==0.38.0

$ python3 ./llvmlite_ctypes_bug.py
Target triple:
x86_64-apple-darwin21.3.0
Target machine data layout:
e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128
Abort trap: 6
"""

import ctypes

from llvmlite import binding



class MyValueType(ctypes.Union):
    _fields_ = [
        ('a', ctypes.c_int64),
        ('b', ctypes.c_int64),
        ('c', ctypes.c_int64),
        ('d', ctypes.c_int64),
        # Comment out or remove the following line and it works.
        ('e', ctypes.c_int64),
    ]



def main():
    binding.initialize()
    binding.initialize_native_target()
    binding.initialize_native_asmprinter()
    binding.check_jit_execution()

    assembly = """
%struct.MyValue = type { i64 }
define %struct.MyValue @my_function() {
    ret %struct.MyValue { i64 123 }
}
"""
    module_ref = binding.parse_assembly(assembly)
    target = binding.Target.from_default_triple()
    target_machine = target.create_target_machine()
    print(f'Target triple:\n{target.triple}')
    print(f'Target machine data layout:\n{target_machine.target_data}')
    engine = binding.create_mcjit_compiler(module_ref, target_machine)
    engine.finalize_object()

    func_addr = engine.get_function_address('my_function')
    func_type = ctypes.CFUNCTYPE(MyValueType)
    func_ptr = func_type(func_addr)
    result = func_ptr()
    print(result.a)



if __name__ == '__main__':
    main()