llvm dev - May 2016 - Problem on cross-compiling compiler-rt

> On May 5, 2016, at 12:11 PM, Renato Golin <renato.golin at
linaro.org> wrote:
> 
> On 5 May 2016 at 19:33, Chris Bieneman via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> I have a patch out for review now (http://reviews.llvm.org/D19742) that
>> allows building builtins without a full toolchain.
> 
> Nice! Does that also allow you to build multiple targets?
No. The plan is to have compiler-rt support one target per-configuration and to
have LLVM & Clang’s build systems manage configuring compiler-rt for each
target.

I’m still working out the exact details of what that will look like, but I’m
expecting to have CMake take a list of targets probably specified by triple.

-Chris

On 5 May 2016 at 21:08, Chris Bieneman <beanz at apple.com>
wrote:
> No. The plan is to have compiler-rt support one target per-configuration
and to have LLVM & Clang’s build systems manage configuring compiler-rt for
each target.
>
> I’m still working out the exact details of what that will look like, but
I’m expecting to have CMake take a list of targets probably specified by triple.
Sounds great, thanks for that work! And let me know when you have
something, I'd like to test it locally.

cheers,
--renato

That's great. For multi targets compilerrt-rts,   in old llvm 3.5
configuremakefileconfigure/makefile system, it will build multiple libs for each
target on the target list pass to clang building. but since you said compiler-rt
now require sysroot for proper headers, then I don't think multi libs can be
built together any more. However, according to my knowledge, without
compiler-rt, a compiler is not able to full functionally work, if assuming it is
the only compiler runtime lib we have. Clang is designed and able to be built
for multi targets, so it should work with different compiler rt libs when it is
built for multi targets. So from this viewpoint, multi target lib build is
essential to support the multi target clang.
I still do not understanding why including libs using system headers in buildin
libs. And what does exactly compiler rt want to replace? In my opinion, it is
libgcc?

Lei Wang
> 在 2016年5月6日，上午5:53，Renato Golin <renato.golin at linaro.org> 写道：
> 
>> On 5 May 2016 at 21:08, Chris Bieneman <beanz at apple.com>
wrote:
>> No. The plan is to have compiler-rt support one target
per-configuration and to have LLVM & Clang’s build systems manage
configuring compiler-rt for each target.
>> 
>> I’m still working out the exact details of what that will look like,
but I’m expecting to have CMake take a list of targets probably specified by
triple.
> 
> Sounds great, thanks for that work! And let me know when you have
> something, I'd like to test it locally.
> 
> cheers,
> --renato