Well done Google. But there is still problem with EDA tool license... Is there any replacement for Cadence Virtuoso tool for chip design?
The efabless people that the talk mentions a bunch of times are using a fully open-source design flow but I think it's a bit hacky (as in, a bunch of command line tools from various open source projects, some of which may be unmaintained judging by the commit logs). They seem to have successfully fabricated a RISC-V based SoC with it though, which is crazy cool.
As somebody with a decent amount of FPGA experience, having a go at setting this software up and seeing if I can get anything to synthesise and through place and route is something I've been intending to have a play with, but I haven't had the spare time.
It uses yosis for synthesis and a few other tools for the rest of the process, and is called Qflow - http://opencircuitdesign.com/qflow/index.html
Now, how do you generate these layouts? It depends on what you are doing. If more on the experimental side of things, writing scripts to generate structures is fine, as long as these conform to the fab-provided design rules. Technically, that's still what everyone is doing at the industrial level, except the scripts -- often written in tcl -- are provided by the fab.
Now if you have some FPGA experience, you are probably interested in logic synthesis tools. There are a few ones, I've seen some academic with their own place-and-route stage, for instance. https://open-src-soc.org/program.html#T-CHAPUT does that, I think.
The slides linked above outline one of the possible ways to do this: leverage chisel ( https://www.chisel-lang.org/) and the FIRRTL intermediate representation for RTL description. A few tools can ingest the output and try to come up with a layout. Hammer (https://github.com/ucb-bar/hammer) is such a tool, but I don't think that PDK is available with it just yet. To be honest, I don't think commercial tools are that advanced, and it would be fairly doable to catch up.
There is some interesting work in this field, but since fabbing is expensive, it tends to be more within the academic community than the free software one. I'd look for papers, not on Github, though that's slowly changing.
The chip design world is a slow beast to turn around: everything in the fabrication process is optimized to maximize yield, hence very little leeway is allowed: "If it ain't broken, don't fix it" is the motto, for good reason: if changing humidity levels 0.2% can make a fab lose millions; they won't try to use new and experimental software.
I'm watching this space, notably with Verilog alternatives such as Migen. The open source community starts to embrace FPGA, wich is already great. I wish more manufacturers opened up their bitstream, so maybe we need an open FPGA? Though this free fabbing offer would be a great fit for Wi-Fi chips, I think. I wonder if People at openwifi (https://github.com/open-sdr/openwifi) are interested?
I hope that gives a few interesting pointers to whoever reads this :)