[Timer] Count number of executed instructions on macOS #2270
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In addition to wall time etc. this should allow us to get less noisy values for time measurements.
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@swift-ci Please test |
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Rebased to target |
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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 LLVMTimers 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/mainis the correct branch to target, please let me know if I should target a different branch.