[llvm-dev] Use of host/target compiler when building compiler-rt

[David Blaikie via llvm-dev]

On Wed, Mar 8, 2017 at 3:52 PM Matthias Braun via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> On Mar 8, 2017, at 3:14 PM, Chris Bieneman via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>
> On Mar 8, 2017, at 3:08 PM, Hal Finkel <hfinkel at anl.gov> wrote:
>
>
> On 03/08/2017 04:55 PM, Chris Bieneman via llvm-dev wrote:
>
> David,
>
> This is an area that has had a lot of development over the last two years.
>
> There are two supported ways in the LLVM build system to build compiler-rt
> with the just-built compiler.
>
> 1) The legacy way is for if compiler-rt is under LLVM/projects. You can
> specify -DLLVM_BUILD_EXTERNAL_COMPILER_RT=On, which will configure
> compiler-rt using the just-built clang after clang is built.
>
>
> Why is this not the default?
>
>
> Two reasons. (1) It is buggy, and nobody fixed the issues because (2) the
> long-term plan is to not support building compiler-rt (or any other runtime
> library) under llvm/projects. The goal is to migrate entirely to
> llvm/runtimes where the support is more complete.
>
>
> From a compiler developers point of view I wanted to stress that we at
> least should keep the option not to do it, as in my experience development
> workflow heavily slows down if you have to wait around for compiler-rt to
> rebuild after every small change you make to the compiler.
>

If that's a valid option, I'd be open to it - it does really slow down the
dev cycle & it's one of the reasons I often end up moving compiler-rt
out/not building it anymore.

I'm not sure if that's an option at the moment - if it is, I'd love to know
how to do that & it might at least unblock my use case anyway, even if
there's still a need for a broader fix.


> Of course I agree that we should switch the default to something that uses
> the just-built compiler so people unaware of these issues get the safe and
> correct thing.
>
> - Matthias
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170309/73fd99fc/attachment.html>