Add llvm.amdgcn.softwqm intrinsic which behaves like llvm.amdgcn.wqm
only if there is other WQM computation in the shader.
Reviewers: nhaehnle, tpr
Reviewed By: nhaehnle
Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, t-tye, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64935
llvm-svn: 367097