llvm dev - Apr 2016 - compiler-rt: inconsistant build of i386 support on x86_64

I'm the maintainer of FreeBSD's llvm packages and I'm running into
trouble building compiler-rt in a consistent way.  In particular,
when building on FreeBSD amd64, the x86_64 libraries always build (as
expected), but depending on something about the build environment, i386
libraries are sometimes built.  My knowledge of CMakeFiles has proved
insufficient to either figure out why this might happen or disable this
behavior.

What cmake flag(s) control the targets that are supported?

Thanks,
Brooks
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Hi Brooks,

Sorry for the delayed response.

There actually isn’t a single flag that controls target architectures, it is
driven by a sequence of compiler checks. When you configure compiler-rt and the
i386 architecture doesn’t get configured, you’ll likely have some errors logged
in the CMakeError.log file.

I’m working on some significant re-working of the compiler-rt build system which
will (among other things) make it more explicit what target you’re building for.
Hopefully this will get better in the near future.

Which compiler-rt libraries are you expecting for each architecture?

Thanks,
-Chris
> On Apr 27, 2016, at 1:27 AM, Brooks Davis via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> I'm the maintainer of FreeBSD's llvm packages and I'm running
into
> trouble building compiler-rt in a consistent way.  In particular,
> when building on FreeBSD amd64, the x86_64 libraries always build (as
> expected), but depending on something about the build environment, i386
> libraries are sometimes built.  My knowledge of CMakeFiles has proved
> insufficient to either figure out why this might happen or disable this
> behavior.
> 
> What cmake flag(s) control the targets that are supported?
> 
> Thanks,
> Brooks
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi Chris,

I ended up hacking the CMakeFiles to never check for -m32 support on
x86_64 which allowed me to produce a consistent set of files across our
supported systems.  I concluded that there was no way I could enumerate
all the ways -m32 might be broken and thus decide to add the i386 files
to the packing list so it was best to just never try to build them.

I'd much prefer a system where you asked for a target and either cmake
determined it could build it or failed.  It sounds like that's the
direction you're heading.

Thanks,
Brooks

On Tue, May 03, 2016 at 08:44:05AM -0700, Chris Bieneman
wrote:
> Hi Brooks,
> 
> Sorry for the delayed response.
> 
> There actually isn???t a single flag that controls target architectures, it
is driven by a sequence of compiler checks. When you configure compiler-rt and
the i386 architecture doesn???t get configured, you???ll likely have some errors
logged in the CMakeError.log file.
> 
> I???m working on some significant re-working of the compiler-rt build
system which will (among other things) make it more explicit what target
you???re building for. Hopefully this will get better in the near future.
> 
> Which compiler-rt libraries are you expecting for each architecture?
> 
> Thanks,
> -Chris
> 
> > On Apr 27, 2016, at 1:27 AM, Brooks Davis via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> > 
> > I'm the maintainer of FreeBSD's llvm packages and I'm
running into
> > trouble building compiler-rt in a consistent way.  In particular,
> > when building on FreeBSD amd64, the x86_64 libraries always build (as
> > expected), but depending on something about the build environment,
i386
> > libraries are sometimes built.  My knowledge of CMakeFiles has proved
> > insufficient to either figure out why this might happen or disable
this
> > behavior.
> > 
> > What cmake flag(s) control the targets that are supported?
> > 
> > Thanks,
> > Brooks
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>