[llvm-dev] [Progress Update] LLVM Runtimes Subdirectory

[Renato Golin via llvm-dev]

Hi Chris,

Your fix made it work, I managed to build all of it to the end. Thanks!


On 27 August 2016 at 00:58, Chris Bieneman <beanz at apple.com> wrote:
> Yes, because it uses the just-built tools, clang is a dependency of the configure step.

Perfect.


> This isn’t explicitly supported yet, but the standard COMPILER_RT_* prefixed options will be passed through.

Right, I'm playing with the flags and not getting anywhere. I tried:

-DCOMPILER_RT_DEFAULT_TARGET_ARCH=
-DCOMPILER_RT_SUPPORTED_ARCH=
-DCOMPILER_RT_BUILTINS_STANDALONE_BUILD=
-DBUILTIN_SUPPORTED_ARCH=

I noticed that RT's builtin-config-ix.cmake only has cross options for
Darwin, would that be the reason?


> The problem is that the top-level CMake doesn’t actually know what targets to generate until after you configure compiler-rt because the capabilities of the compiler you build will impact what targets get generated.

Hum, that sounds like a chicken and egg problem. Maybe some additional
CMake flag to facilitate the cross options of RT's builtin (as we
discussed above) could "assume" the targets directly.

A first implementation would fail later if Clang can't target the arch
you asked (ex. if you removed it from LLVM_TARGETS_TO_BUILD), but an
intersection check on both lists could yield some pre-checks to make
it a cmake error instead.

cheers,
--renato