Add back demangling support about inferno HOT 5 CLOSED

on macOS,
sudo flamegraph rg will produce mangled names:

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@king6cong This makes sense. The testing I did before was only for perf since inferno didn't yet support DTrace. Since you're on macOS, it's using DTrace. DTrace tries to demangle the names, but I believe it's demangling Rust names like C++. This sort of works, but not very well. After DTrace does its demangling, the result can't be demangled with the rustc demangler.

One way we could work around this is to pass the -xmangled option to dtrace so the names remain mangled. Then we could change the dtrace collapser to demangle the names. This would give much better results.

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I added support for this in a branch using the symbolic_demangle crate. The problem is perf is already doing a great job demangling function names for me in all of the tests I've tried.

I used perf on some Rust programs to see if I could ever get function names that don't demangle correctly. The only way the names come out mangled is if I explicitly pass --no-demangle to perf script. I wonder why other people are getting different results.

Have you seen mangled Rust names from perf?

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BTW, if I do pass --no-demangle to perf script, my branch's version of inferno-collapse-perf successfully demangles the function names. I could create some tests this way, but I'm wondering why perf's demangling isn't working for some people.

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It could be that those people are using older versions of perf with broken or outdated demangling. Given your experiments, I'm inclined to just close this and leave perf to deal with it. If anyone having this problem could provide some more context, that'd be great!

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