QuickLogic (EOS S3) do actively contribute to the open stack (to support their own FPGA series) themselves.

https://www.crowdsupply.com/quicklogic/quickfeather

OTOH, while not actively contributing, Lattice (iCE40, ECP5) are aware and do tolerate the open stack.

They reversed some new terms of use recently (stating it was a mistake), when the community realized they had added some clauses against reverse engineering and made a lot of noise about it. It means they are aware of the positive effect the open stack has provided from a marketing standpoint.

AFAIK, none.

Recently Lattice updated their licensing forbidding reverse engineering, but changed their mind once the community complained.

Also, a while back, lattice added support to something that was already implemented on the open source tools, but with a different name -- thus, code that worked on open source don't work on the official tool. (I'm not sure if this was "fixed").

The open source tools have been create by hard work of many hackers. If you want to know more, watch this 35C3 talk [1] where MathiasL describes how they reverse engineered the Artix-7 bitstream.

Last time I checked, Symbflow [2] only supported Lattices FPGAs and Artix-7 (smallest fpga from Xilinx 7-series). Both are quite small FPGAs.

[1] https://www.youtube.com/watch?v=Y1Wwa8csFjk [2] https://symbiflow.github.io/

Probably Lattice, although considering the field that's not saying much. But they at least removed a license term on their software that some of the FOSS toolchain developers complained about.

FPGA tools allow a lot of customization if you need it, what difference will it make if they are fully opensource? FPGA chip design isn't opensource anyway

The vendors tools are notoriously buggy, don't conform to the HDL standard and lacks support to inference of some functional block (cascade DSPs and FIFOs for example).

Some FPGAs features are only available on yearly paid subscription. Also, the license is very restrictive, publishing benchmarking is not allowed, therefore, there is no public information on how to chose a computer to have faster synthesis.

Other than solving those issues, an open source framework enable the researches to search for newer place and route algorithms; enables new HDL languages to target the actual hardware instead of using verilog as intermediate language.

Well you can say the same thing about computers. But if computers were as closed as some FPGA offerings, then we wouldn't have had Linux and its ecosystem of open/free tools, for instance.