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

[Siva Chandra via libc-dev]

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
>>> 礼
>>> 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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