Summary:
Extend the SI Load/Store optimizer to merge MIMG load instructions. Handle
different flavours of image_load and image_sample instructions.
When the instructions of the same subclass differ only in dmask, merge
them and update dmask accordingly.
Reviewers: nhaehnle
Reviewed By: nhaehnle
Subscribers: arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64911
llvm-svn: 374984