f3f28323ad
introduces the data access profile format as a payload inside
[memprof](https://llvm.org/docs/InstrProfileFormat.html#memprof-profile-data),
and the MemProfUse pass reads the memprof payload.
This change extends the MemProfUse pass to read the data access profiles
to annotate global variables' section prefix.
1. If there are samples for a global variable, it's annotated as hot.
2. If a global variable is seen in the profiled binary file but doesn't
have access samples, it's annotated as unlikely.
Introduce an option `annotate-static-data-prefix` to flag-gate the
global-variable annotation path, and make it false by default.
https://github.com/llvm/llvm-project/pull/155337 is the (WIP) draft
change to "reconcile" two sources of hotness.
Now that readMemProf calls two helper functions handleAllocSite and
handleCallSite, we can simplify the control flow. We don't need to
use "continue" anymore.
Continuing the effort to refactor readMemProf, this patch introduces
handlCallSite to handle, well, call sites.
Moving the code requires taking CallSiteEntry and CallSiteEntryHash
out of readMemProf.
We could simplify some code, but I'm keeping this patch very simple to
facilitate the review process. For example, we could simplify the
control flow near the end of readMemProf, but we can address that
later.
This patch creates a helper function named handleAllocSite to handle
the allocation site. It makes readMemProf a little bit shorter.
I'm planning to move the code to handle call sites in a subsequent
patch. Doing so in this patch would make this patch a lot longer
because we need to move other things like CallSiteEntry and
CallSiteEntryHash.
Most of the recent development on the MemProfiler has been on the Use part. The instrumentation has been quite stable for a while. As the complexity of the use grows (with undrifting, diagnostics etc) I figured it would be good to separate these two implementations.
