llvm dev - May 2016 - llvm-toolchain-3.8 on lower arm targets, specifically Debian armel and Raspbian.

On 17/05/16 18:07, Tim Northover wrote:
> Yes, it looks like we'd need to conditionally compile these functions
> in ARM mode and use the v6 barrier instead of dmb ("mcr p15, #0, r0,
> c7, c10, #5" I believe) to support the ARM1176JZF-S in RPi. You'd
> probably also want the build system to use an explicit -march=armv6 or
> something so you're not at the mercy of how the host compiler was
> configured.
>
> I suspect you're the first person to try and get compiler-rt going for
> pre-v7 hardware, which most of us prefer to pretend never happened
> most of the time.
>    
Thank you very much for your reply.

Can you clarify what exactly compiler-rt is and how important it is to 
the stack as a whole. It seems that llvm-toolchain-3.7 built 
successfully on raspbian without building compiler-rt while 
llvm-toolchain-3.8 built an armv7 compiler-rt (and hence got blocked 
from entering the raspbian repos).

> Can you clarify what exactly compiler-rt is and how important it is to the
> stack as a whole. It seems that llvm-toolchain-3.7 built successfully on
> raspbian without building compiler-rt while llvm-toolchain-3.8 built an
> armv7 compiler-rt (and hence got blocked from entering the raspbian repos).
Compiler-rt is the equivalent of libgcc, and Clang can use the
existing host's libgcc quite happily so it's really not that important
unless you're trying to build a GNU-free environment for whatever
reason.

Cheers.

Tim.

On 17/05/16 22:38, Tim Northover wrote:
> Compiler-rt is the equivalent of libgcc, and Clang can use the
> existing host's libgcc quite happily so it's really not that
important
> unless you're trying to build a GNU-free environment for whatever
> reason.
>    
Thanks

Can you tell me how I would go about telling the cmake buildsystem 
(which is what the Debian packaging currently seems to use) that I want 
it to build without compiler-rt?