[PATCH] D46009: [AArch64] Custom Lower MULLH{S, U} for v16i8, v8i16, and v4i32

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer added a comment.

Sorry, I needed to get up to speed here, also with this hacker's delight trick. 
I think it would be good if you add some comments to LowerMULH what we are trying to do here.

I think I have some more comments, mainly about the tests:

- you're not checking the magic number (e.g. in the first test "movi  v1.16b, #57"), but I think that is quite relevant here.
- you're only using constant vectors with value 9. I think it would be good to vary here.
- I think you should also define the operands of the smull2 and smull instructions with regexps, and use them.
- nit: some functions still have inconsistent names, e.g. function "umul8xi16" tests "udiv <16 x i8>"


https://reviews.llvm.org/D46009