[Yosys] init

[sjkelly]

This adds support for building Yosys, the open source synthesis suite for FPGAs and ASICs.

[giordano]

GCC 10 is a bit too much, especially for a C++ program

[sjkelly]

Should I drop that line all together?

[sjkelly]

hmm the make CONFIG=${CC} is not handled by the Yosys makefile. They are expecting gcc but cc is passed. Should this be patched or is there a mechanism to do this here?

[giordano]

0d27f38 (#3435) 🙂

[giordano]

Actually we already have ABC, but of course here they use a fork...

[sjkelly]

Was about to say. Should we package YosysABC separate?

[giordano]

Would you be OK with skipping ABC at the moment? At least to see whether it'd succeed without it, they're all choking there

[sjkelly]

The diff doesn't look like it should affect, and we can use the in-tree ABC. most (all?) of the yosys ABC changes are related to WASM support: berkeley-abc/abc@master...YosysHQ:yosys-experimental

[sjkelly]

Please do whatever experiments you like. I am following along and learning.

[sjkelly]

Suggested change

	make CONFIG=${CONFIG} PREFIX=${prefix} -j${nproc}
	make CONFIG=${CONFIG} PREFIX=${prefix} LINK_ABC=1 -j${nproc}

[giordano]

I'd like to try

Suggested change

	make CONFIG=${CONFIG} PREFIX=${prefix} -j${nproc}
	make CONFIG=${CONFIG} PREFIX=${prefix} ENABLE_ABC=0 -j${nproc}

to completely disable ABC, and see what happens, if you're OK

[sjkelly]

FYI Nix builds with separate ABC. I cribbed from there: https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/compilers/yosys/default.nix

[sjkelly]

with 3177fcd

I get:

[22:40:16] /opt/i686-linux-gnu/bin/i686-linux-gnu-ld: passes/techmap/abc.o: unrecognized relocation (0x2b) in section `.text'
[22:40:16] /opt/i686-linux-gnu/bin/i686-linux-gnu-ld: final link failed: Bad value
[22:40:16] clang-12: error: linker command failed with exit code 1 (use -v to see invocation)

on most all platforms. I am setting preferred_gcc_version=v"8" per troubleshooting.md.