[single-exe] Enable LTO when building corebundle #26697
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Curious to know where the ~20-35ms of startup time went when using LTO. |
| @@ -108,6 +108,8 @@ llvm_link="$(locate_llvm_exec link)" | |||
| [[ $? -eq 0 ]] || { echo "Unable to locate llvm-link"; exit 1; } | |||
| llvm_nm="$(locate_llvm_exec nm)" | |||
| [[ $? -eq 0 ]] || { echo "Unable to locate llvm-nm"; exit 1; } | |||
| llvm_ranlib="$(locate_llvm_exec ranlib)" | |||
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I wonder why is adding the ranlib necessary.
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My surface understanding standing is that llvm-ranlib is intended to handle the clang output when when using the -flto flag, whereas the standard ranlib does not. Really, I just hit errors with using the standard ranlib when trying to do this and looking around online indicated that llvm-ranlib should be used in order to use LTO.
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It was removed in #1363 because openSUSE distro did not have ranlib. If openSUSE is not exercised in the CI, that might be broken.
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@am11 thank you for the info. I had a feeling that it was removed intentionally in the past, but I haven't remembered the reason. We don't build anything on OpenSUSE in our CI.
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I'm honestly not sure where exactly the startup time went (I wasn't really expecting it, but definitely not complaining). I think there were still issues getting dependable traces. |
Using the link-a-thon app, this drops about 25-30ms in total startup (startup + first request) and 0.35MB in the bundled app size.
Without LTO (28.91 MB app):
With LTO (28.56 MB app):