[llvm] [CodeGen] Add EmitCodeGenCallSiteInfo flag (PR #206668)

[Nikita Popov via llvm-commits]

nikic wrote:

After looking in a bit more detail at what this call-site info thing is, I think I'm even more confused about this patch. As far as I can tell, this call-site info is a purely internal thing, it's not something that gets emitted into the artifact, right?

In that case: Why does this need to be enabled with a separate flag? If the machine outliner needs it, why is it not automatically enabled if the machine outliner is enabled?

I could even generalize this question one step and ask: Why is this functionality behind a flag at all? From some quick testing, it looks like enabling it has no compile-time impact -- but there is some max-rss impact: https://llvm-compile-time-tracker.com/compare.php?from=cdd1900816f625eb1f38a6e755c49ccadec56209&to=313783ca510a364250398e266f2faad22093a8db&stat=max-rss I guess that's my answer. (Though I don't know if it *needs* to use that much memory, I haven't checked the implementation.)

https://github.com/llvm/llvm-project/pull/206668