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

Ebrahim Byagowi via libc-dev libc-dev at lists.llvm.org
Sun Jan 31 01:16:18 PST 2021

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 :)

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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