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

[James Greenhalgh via llvm-commits]

jgreenhalgh added a comment.

> It'd be good if James could have a final look, but I'm ok with the change.


I think this will be fine. Missing the constants and labels might come back to bite you (I found an example of s390 using the "X" constraint in the kernel [ arch/s390/include/asm/jump_label.h ] to get at a label for hotpatching), but the break is no worse than you have at the moment (and that's s390, I didn't see anything scary in arch/arm or arch/arm64).

If you're happy to be more restrictive than GCC here, then I think think the patch is fine.

Please heavily comment the testcases to reflect that they are not representative of the way the "X" constraint should be used in the real world, and you may want to add further comments to the lowering function to make it clear that it is tighter than neccessary.


http://reviews.llvm.org/D19061