[PATCH] D19061: [ARM] Add support for the X asm constraint

[Renato Golin via llvm-commits]

rengolin added a comment.

In http://reviews.llvm.org/D19061#401361, @sbaranga wrote:

> It is true that GCC would be more efficient in some cases (one example would be FP constants), but we would still fit into the definition of "no constraint whatsoever" and therefore correct - which is an improvement from the current situation, where we'll simply crash on this constraint.


I agree bad codegen trumps ICE crashes, but James mentioned it "might well break use cases". I'm interested in those...

James, do you have some pointers on the expected usage of this constraint in the wild? The more the merrier!

cheers,
--renato


http://reviews.llvm.org/D19061