[Gold] Skip linking when output file is newer than all inputs?

[Niklas Hambüchen]

Hi,

I'm working on speeding up some builds and looking around the
--incremental options, I came across the following question:

Is it possible to skip linking altogether when an existing output
executable is newer than all inputs?

I have seen mtime checks in the code, but when I re-run gold
--incremental multiple times, it still runs for around 500 ms, so it
does perform some work, and afterwards the mtime on the output
executable is updated.

I am new to linker internals; would you mind giving me a short
explanation on what is being done here?

Thanks you (and thanks for gold)
Niklas