Okaaay... sorry for the noise, I don't have the _same_ problem.

My problem is not due to a change in either mesa or llvm but cs go as it seems.
I switched to a llvm r251632 (October 29th) and mesa
c6b24448b578c4a8ab031923df3ef1e2d865d5bb (also October 29th) and my problems is
still there.

I'm opening a new bug.