llvm dev - Jul 2020 - Preserving terminator-instruction metadata in the LoopExtraction pass

Hello,

I've been working recently with the loop extraction pass in LLVM8.0 and
LLVM's profile instrumentation metadata.
Just wanted to ask if there is a quick way to preserve Terminator Instruction
profile weight metadata on extracted loops. I'm aware that
IPO/LoopExtractor.cpp uses utils/CodeExtractor.cpp to extract a subset of basic
blocks from a function and that it seems to be creating a new function and
definitely the profiling info is being lost in that step.

Can anyone more experienced with the loop extraction pass provide some feedback
on how to preserve per basic-block metadata work nicely with Code Extraction? My
intuition so far is that the BasicBlocks set named "Blocks" removes
and adds new basic blocks in severSplitPHINodes in CodeExtractor.cpp and then
those blocks are used in moveCodeToFunction and I'm still working on saving
the metadata from the old blocks into the new ones but since I'm having a
hard time understanding "severSplitPHINodes" any info about whether
this would be the right way to preserve profiling info or if I'm overlooking
something obvious.

Thanks a lot,
Iulian