Summary:
We already do it for splat constants, but not just values.
Also, undef cases are mostly non-functional.
The original commit was reverted because
it broke tests for amdgpu backend, which i didn't check.
Now, the backed was updated to recognize these new
patterns, so we are good.
https://bugs.llvm.org/show_bug.cgi?id=37603https://rise4fun.com/Alive/cplX
Reviewers: spatel, craig.topper, mareko, bogner, rampitec, nhaehnle, arsenm
Reviewed By: spatel, rampitec, nhaehnle
Subscribers: wdng, nhaehnle, llvm-commits
Differential Revision: https://reviews.llvm.org/D47980
llvm-svn: 334818
84c11aed10