This reverts commit 43ae4b62b2.
This was intended to be practically NFC in terms of the overall
opt pipeline, but there is experimental data showing that code
changes occurred here:
https://llvm-compile-time-tracker.com/compare.php?from=772aa05452f8ff90a47168e6801cda2acb5a1873&to=43ae4b62b2671cf73e691c0b53324cd39405cd51&stat=size-text