[libc-dev] [llvm-dev] How about add webassembly/wasi support in llvm-libc.

Siva Chandra via libc-dev libc-dev at lists.llvm.org
Sun Jan 31 21:27:29 PST 2021

On Sun, Jan 31, 2021 at 1:16 AM Ebrahim Byagowi <ebraminio at gmail.com> wrote:

> Okay I am making my way through this somehow, hopefully I can reach to
> somewhere and document the steps so feel free to ignore my last email here.
> Thanks :)


If you still need to ask questions, feel free to do so. Also, if you find
something can be done better, feel free to suggest.

Siva Chandra

> On Sat, Jan 30, 2021 at 8:31 PM Ebrahim Byagowi <ebraminio at gmail.com>
> wrote:
>> Hi Siva,
>> I wonder if you can help me to test this, I have a llvm build setup so
>> having some quick instructions on how to test this even on x86_64 would be
>> nice so maybe I can adopt it with my wasm work.
>> Thanks!
>> On Wed, Sep 23, 2020 at 11:33 PM Siva Chandra <sivachandra at google.com>
>> wrote:
>>> On Wed, Sep 23, 2020 at 12:47 PM Ebrahim Byagowi <ebraminio at gmail.com>
>>> wrote:
>>>> Somehow I wish not all parts of a libc but parts that can be provided
>>>> without a JavaScript wrapper for .wasm can be provided from llvm's libc
>>>> (leaving a stab implementation for the rest like file system). I've put
>>>> together a minimal libc on [1] so using a 26kb .wasm binary file one can
>>>> decode both PNG and JPG using this [2] simple to integrate JavaScript code,
>>>> can be easily ported in other contexts .wasm can be interpreted without
>>>> worrying about a helper. I had to use -nostdlib and -nostdinc in my build
>>>> script but I wished the llvm-libc initiative can make it simpler so I don't
>>>> have to put together a minimal libc for my need.
>>> Such a use case is supported by LLVM libc [*]. One will have set up a
>>> few config files for wasm. See
>>> https://github.com/llvm/llvm-project/blob/master/libc/config/linux/api.td
>>> and
>>> https://github.com/llvm/llvm-project/blob/master/libc/config/linux/x86_64/entrypoints.txt
>>> .
>>> The tricky part would be header files. When you pick only a part of LLVM
>>> libc, where will you get the libc headers from? You can choose to use
>>> headers from the other libc and stick to platform independent and ABI
>>> insensitive parts from LLVM libc.
>>> [*] Since Linux is the only platform we test on currently, there might
>>> be some holes/bugs in LLVM libc's infrastructure that might need to be
>>> plugged/fixed before bringing up LLVM libc for wasm.
>>> Something similar can be achieved in Rust world using --target
>>>> wasm32-unknown-unknown e.g. [3] which I guess can be best lead here
>>>> also in terms what can be in scope of this work.
>>>>  [1]: https://github.com/harfbuzz/harfbuzzjs/tree/edf1d8b/libc
>>>>  [2]:
>>>> https://github.com/harfbuzz/harfbuzzjs/blob/gh-pages/stb-image/index.html
>>>>  [3]: https://github.com/RazrFalcon/ttf-parser/commit/b0cfc67
>>>> On Wed, Sep 23, 2020 at 9:16 PM Siva Chandra via libc-dev <
>>>> libc-dev at lists.llvm.org> wrote:
>>>>> +cc libc-dev
>>>>> On Wed, Sep 23, 2020 at 9:44 AM 罗勇刚(Yonggang Luo) via llvm-dev <
>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>> Cause llvm-libc are in early stage, and we can easily catch up the
>>>>>> support with linux.
>>>>>> After we add wasi support in llvm-lic, we can easily get a usable
>>>>>> llvm-libc across different platform such as linux/windows/macos/android.
>>>>>> don't know if iOS is a target, but these target are very much enough
>>>>> I do not see any technical blockers for the platform independent
>>>>> parts. Of course, work has to be done to set up the build etc.
>>>>> What exactly do you mean by, "we can easily get a usable llvm-libc
>>>>> across different platforms such as linux/windows/macos/android."
>>>>>> --
>>>>>>          此致
>>>>>>>>>>>> 罗勇刚
>>>>>> Yours
>>>>>>     sincerely,
>>>>>> Yonggang Luo
>>>>>> _______________________________________________
>>>>>> LLVM Developers mailing list
>>>>>> llvm-dev at lists.llvm.org
>>>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>> _______________________________________________
>>>>> libc-dev mailing list
>>>>> libc-dev at lists.llvm.org
>>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/libc-dev
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