Hello.

I've got a patch candidate that leverages partial linking for a couple of selected object files.

I'm sending make all-host- jX results for my machine:

before: 3m18s (user 32m52s)
https://gist.githubusercontent.com/marxin/223890df4d8d8e490b6b2918b77dacad/raw/1dd5eae5001295ba0230a689f7edc67284c9b742/gcc-all-host.svg

after: 2m57m (user 35m)
https://gist.githubusercontent.com/marxin/223890df4d8d8e490b6b2918b77dacad/raw/d659b2187cf622167841efbbe6bc93cb33855fa9/gcc-all-host-partial-lto.svg

One can utilize it with:
make -j16 all-host PARTIAL_LTO=1

@Segher, Andrew: Can you please measure time improvement for your slow bootstrap?
One can also tweak --param=lto-partitions=16 param value.

Thoughts?
Thanks,
Martin