Supporting alternative toolchains on Windows

[Dalibor Topic]

On 11.03.2022 18:18, Thomas Stüfe wrote:
> As Dalibor wrote, I would not expect too many performance surprises.
> 
> That said, a more pragmatic approach may be to create a shim layer for
> visual studio compiler and linker, e.g. a fake "cl.exe" and "link.exe" that
> translate VC++ options and paths to whatever toolchain you like. That way
> you don't have to touch the OpenJDK make at all. I know it works in
> principle since I have such a thing in the past, albeit for a different
> product and a different target toolchain.
> 
> I would not be surprised if such a thing exists already. It seems such an
> obvious idea.

For clang there is https://clang.llvm.org/docs/UsersManual.html#clang-cl 
but I have not tried it myself. But then again the linker step might be 
problematic.

cheers,
dalibor topic

> 
> Cheers, Thomas
> 
> On Fri, Mar 11, 2022 at 2:35 PM Julian Waters <tanksherman27 at gmail.com>
> wrote:
> 
>> Darn, seems like it'll be much harder than I expected. Since multiple
>> toolchains are supported for macOS and Linux, I assumed a slight patch
>> would help get it to work on Windows. Looking through the stuff in make
>> though, it appears a lot of the build system implicitly expects the
>> compiler for Windows to always be Visual C++, which doesn't really help
>> that much (Though the fact that we can exclude many versions of gcc, such
>> as Cygwin's and old MinGW binaries helps a lot). The build process for the
>> newer Windows ports of gcc are surprisingly similar to Visual C++ though
>> (Eg rc can be swapped out for windres) so this might hopefully be something
>> I can try exploring in the future (Gonna look a bit harder at make and
>> write what I can find back to this mailing list in the meantime). It'd be
>> interesting if benchmarks of the JVM compiled with different compilers on
>> Windows can be compared side by side on the off chance this becomes a
>> reality though
>>
>> best regards,
>> Julian
>>
>> On Fri, Mar 11, 2022 at 9:16 PM Magnus Ihse Bursie <
>> magnus.ihse.bursie at oracle.com> wrote:
>>
>>> On 2022-03-11 12:55, Julian Waters wrote:
>>>
>>>> Hi all,
>>>>
>>>> How feasible would it be/much effort would it require to support
>>> compiling
>>>> with alternate toolchains on Windows besides Visual C++ (like the
>> Windows
>>>> ports of clang and gcc) if we restrict the allowed toolchains to only
>>> those
>>>> that link against the ucrt? (Toolchains linking against the dated
>> msvcrt
>>>> would present too many issues to work with)
>>>
>>> That'd be a huge undertaking. And any such patch would only be accepted
>>> into the code base if the organization behinded appeared trustworthy in
>>> their long-term commitment to keeping it working.
>>>
>>> /Magnus
>>>
>>>
>>>
>>

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