Re: [gentoo-musl] [GSoC] musl and x32

[Lei Zhang]

2016-06-02 13:13 GMT+08:00 Anthony G. Basile <blueness@g.o>:
> On 6/1/16 11:35 PM, Lei Zhang wrote:
>>
>> Currently I'm considering introducing a new ABI type "musl" into clang, so
>> we can build a native clang targeting "x86_64-linux-musl". But I notice
>> there's also an ABI type specifically for x32, named "gnux32". Then what
>> about musl on a x32 platform? Should I name it "muslx32" or something? I
>> don't know why x86 and x86_64 can live with the same ABI name, while x32
>> can't...
>
> 1) i tried x32 + musl + gcc and ran into quite a few issues and gave up.
> i don't recall what those issues are right now, but they were basically
> lost of compile time breakage of packages.  since i'm not a big fan of
> x32 i didn't put a lot of effort in and when i saw it was a steep climb,
> i had bigger fish to fry.

musl's FAQ says the support for x32 is still experimental; so the unstability
is kind of expected.

>
> 2) i don't know what you mean by "should i name it muslx32".  what is
> the "it" in your sentence?

I mean the ABI part in a toolchain triplet.

> if its the the toolchain tuple, that should
> not contain the abi name in it because a given toolchain is able to emit
> different abis.  for example gcc on x86_64 architecture can produce
> three abis (if the corresponding libc's are available):  gcc -m32, gcc
> -m64, gcc -mx32

Taking "x86_64-linux-musl" for example, the "musl" is the ABI name and
should be in the triplet, right? Otherwise how do we tell which libc
this toolchain
is using?

You're right a "x86_64-linux-gnu" toolchain should be able to able to produce
x86, x86_64 and x32 executables. That's why I'm confused when seeing
"gnux32" as a separate ABI name. This is a code snippet from clang:

  enum EnvironmentType {
    UnknownEnvironment,

    GNU,
    GNUEABI,
    GNUEABIHF,
    GNUX32,
    CODE16,
    EABI,
    EABIHF,
    Android,

    MSVC,
    Itanium,
    Cygnus,
    AMDOpenCL,
    CoreCLR,
    LastEnvironmentType = CoreCLR
  };

The "Environment" refers to the last part of a triplet.


Lei