The original commit message for the order files says "It's OK if these files are slightly out of date", and that's true. However, in the 11 months since then, our builds have undergone major changes that affect large numbers of final symbol names, like switching from Frontend to IR PGO, and enabling the new pass manager. I think at this point a refresh wouldn't hurt.
I generated these files by locally creating a "stage 2.5" PGO build that's both
-finstrument-functions-after-inlining, and otherwise following the instructions from bug 1444171. Doing this at the
use stage rather than the
gen stage lets us get around the problem of mixing IR and Frontend instrumentation. It also gets us a more accurate picture of the final optimizations.
I haven't exhaustively run this through Talos. I did some spot checks, most were within noise, Speedometer maaybe gets 0.6%. I don't think this is worth hogging the talos machines for a full run, we can get the results after landing.
If for no other reason, this is worth doing to reduce 8000 lines of warning LNK4037 (order file refers to a nonexistent symbol) in build logs down to about 150.