[amdgpu] Skip non-instruction values in CF user tracing.
- CF users won't be non-instruction values. Skip them to save the compilation time. It's especially true when there are multiple functions in that module, where, says, a constant may be used in most functions. The current CF user tracing adds significant overhead.
Reviewers: alex-t, rampitec
Subscribers: arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D72174