[PATCH] D49924: [DAGCombiner] transform sub-of-shifted-signbit to add

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri accepted this revision.
lebedev.ri added a comment.
This revision is now accepted and ready to land.

The code+x86 test change looks ok to me.

In aarch64 case, as far as i can tell, the main change is that we avoided having to materialize the immediate in register,
although i'm not sure why we no longer fuse the shift into `Operand2` of `add`/`sub`, commutativity overlook?
https://godbolt.org/g/yAFJS4 - but i don't think i'm comparing them correctly, that syntax is rather alien to me.
So yeah, not sure about aarch64.


https://reviews.llvm.org/D49924