[Timer] Count number of executed instructions on macOS #2350
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In an effort to get performance timers for the Swift parser that are as accurate as possible, I found this PR by Graydon (swiftlang/swift#18658) from a couple years ago, adding a performance metric that counts the number of executed instructions on macOS. According to Graydon (and my intuition), this number is a lot less noisy than the time values.
With this PR, I'm trying to taking the measurements a little bit further by recording them with every LLVM
Timer
. This way, we get the measurement for free in every place that LLVMTimer
s are used (which happens to include measurements for the Swift parser, my original goal).The code is mostly copy-based from either Graydon's PR or other places in
Timer.h/cpp
. I would appreciate a thorough code review, in particular regarding the implications of my changes toCMakeList.txt
.Also: I'm not sure, if
swift/main
is the correct branch to target, please let me know if I should target a different branch.This supersedes #2270 which targeted
apple/main
.