Patch https://reviews.llvm.org/D52697 introduced a regression on certain platforms. (for example on quick-bench: http://quick-bench.com/kguTLHndCQWFuzlxJQT4tJQa_p8)
This patch should fix that regression: http://quick-bench.com/fcV9gaAWPeqB_3-AePOw9H2wxXU
I do not know yet why it behaves like it is.
I do think that these measurements are correct since I've tried multiple variations on quick-bench and didn't stumble into the opposite.
On my machine this regression does not reproduce.
As part of the review, please check that you do not run into this issue on your machine.
Related bug: https://bugs.llvm.org/show_bug.cgi?id=39129