[PATCH] D21991: [libunwind][ARM] Improve unwinder stack usage - Make WMMX support optional

[Asiri Rathnayake via cfe-commits]

rmaprath added a comment.

In http://reviews.llvm.org/D21991#474736, @compnerd wrote:

> I don't think that clang nor LLVM have much in terms of support for XScale.  Can we do something more convoluted perhaps?  I like the preprocessor based approach.  However, if the compiler doesn't define it with the correct target, we define it and push it into the CPPFLAGS.  This way, in the future, we can rely on the compiler to do the right thing and eventually lose the cmake magic.


Sounds good to me.

Just to confirm, we keep the cmake option and make it define `__ARM_WMMX` instead of `_LIBUNWIND_ARM_WMMX`? Or did you mean we try to figure it out based on the target? I think the latter would be very complicated; WMMX is not an architectural feature but an extension supported on some processors (like the PXA series: http://www.marvell.com/application-processors/pxa-family/).

WDYT?

Thanks.

/ Asiri


http://reviews.llvm.org/D21991