Re: [PATCH] tests/tcg: Suppress compiler false-positive warning on sha1.c

["Alex Bennée" <alex.bennee@linaro.org>]

Brian Cain <brian.cain@oss.qualcomm.com> writes:

> On 3/4/2025 6:51 AM, Peter Maydell wrote:
>> On Tue, 4 Mar 2025 at 11:56, Alex Bennée <alex.bennee@linaro.org> wrote:
>>> Peter Maydell <peter.maydell@linaro.org> writes:
>>>> +# GCC versions 12/13/14/15 at least incorrectly complain about
>>>> +# "'SHA1Transform' reading 64 bytes from a region of size 0"; see the gcc bug
>>>> +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106709
>>>> +# Since this is just a standard piece of library code we've borrowed for a
>>>> +# TCG test case, suppress the warning rather than trying to modify the
>>>> +# code to work around the compiler.
>>>> +sha1: CFLAGS+=-Wno-stringop-overread
>>>> +
>>> Sadly this breaks the hexagon compiler:
>>>
>>>    error: unknown warning option '-Wno-stringop-overread' [-Werror,-Wunknown-warning-option]
>>>    Traceback (most recent call last):
>>>      File "/home/alex/lsrc/qemu.git/tests/docker/docker.py", line 683, in <module>
>>>        sys.exit(main())
>>>                 ^^^^^^
>>>      File "/home/alex/lsrc/qemu.git/tests/docker/docker.py", line 679, in main
>>>        return args.cmdobj.run(args, argv)
>>>               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>      File "/home/alex/lsrc/qemu.git/tests/docker/docker.py", line 657, in run
>>>        return Docker().run(cmd, False, quiet=args.quiet,
>>>               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>      File "/home/alex/lsrc/qemu.git/tests/docker/docker.py", line 370, in run
>>>        ret = self._do_check(["run", "--rm", "--label",
>>>              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>      File "/home/alex/lsrc/qemu.git/tests/docker/docker.py", line 247, in _do_check
>>>        return subprocess.check_call(self._command + cmd, **kwargs)
>>>               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>      File "/usr/lib/python3.11/subprocess.py", line 413, in check_call
>>>        raise CalledProcessError(retcode, cmd)
>>>    subprocess.CalledProcessError: Command '['podman', 'run', '--rm', '--label', 'com.qemu.instance.uuid=5bbb7b6ed2ea4377b9b6d646859ec4ea', '--userns=keep-id', '-u', '1000', '-w', '/home/alex/lsrc/qemu.git/builds/all/tests/tcg/hexagon-linux-user', '-v', '/home/alex/lsrc/qemu.git/builds/all/tests/tcg/hexagon-linux-user:/home/alex/lsrc/qemu.git/builds/all/tests/tcg/hexagon-linux-user:rw', '-v', '/home/alex/lsrc/qemu.git:/home/alex/lsrc/qemu.git:ro,z', 'qemu/debian-hexagon-cross', 'hexagon-unknown-linux-musl-clang', '-Wno-incompatible-pointer-types', '-Wno-undefined-internal', '-fno-unroll-loops', '-fno-stack-protector', '-Wall', '-Werror', '-O0', '-g', '-fno-strict-aliasing', '-Wno-stringop-overread', '-mv73', '-O2', '-static', '/home/alex/lsrc/qemu.git/tests/tcg/multiarch/sha1.c', '-o', 'sha1', '-static']' returned non-zero exit status 1.
>>>    filter=--filter=label=com.qemu.instance.uuid=5bbb7b6ed2ea4377b9b6d646859ec4ea
>>>    make[1]: *** [Makefile:122: sha1] Error 1
>>>    make: *** [/home/alex/lsrc/qemu.git/tests/Makefile.include:52: build-tcg-tests-hexagon-linux-user] Error 2
>>>
>>> Is it that new an option?
>> I think it's new-ish (gcc 11?). On the other hand
>
>
> I was going to volunteer to update the toolchain used for hexagon to
> address this.  But unfortunately this warning is still not supported
> in clang 21.
>
> https://github.com/llvm/llvm-project/issues/72455 sounds like it's not
> very likely to arrive any time soon.
>
>
> So "-Wno-unknown-warning-option" does indeed seem like a good workaround.
>
>
>> -Wno-unknown-warning-option is quite old, and would suppress
>> this error. If we do
>>   CFLAGS+=-Wno-unknown-warning-option -Wno-stringop-overread

Workaround is fine for the time being then.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro