Integrate yosys-slang

[povik]

Add yosys-slang as a submodule and provide SYNTH_USE_SLANG option.

Changes from #2875 (now superseded):

• new VERILOG_DEFINES variable piped into both yosys-slang and Yosys frontend
• split RTLIL_FILE from VERILOG_FILES
• updated yosys-slang with build system changes
• convert all Ibex configs

I've tested with @jeffng-or's cva6 config from #2939

[povik]

Marking this as do not merge pending the resolution of povik/yosys-slang#120 which breaks build_openroad.sh --local

EDIT: resolved

[oharboe]

non-sequitor:

Longer term I'd like to see builds moved to bazel where there's no need to add submodules, just specify version and URLs + any patches of dependencies in MODULE.bazel.

[povik]

Because we've reordered commands in the synthesis script, the change impacts non-slang designs too. mock-array fails with the following. Should I package a reproducer?

asap7 mock-array (base)
 Last log file 5_1_grt.log
 Found 2 errors in the logs.
     [ERROR DRT-0073] No access point for ces_1_0/io_ins_left[10].
     [ERROR DRT-0073] No access point for ces_0_0/io_ins_left[10].

[oharboe]

Because we've reordered commands in the synthesis script, the change impacts non-slang designs too. mock-array fails with the following. Should I package a reproducer?

asap7 mock-array (base)
 Last log file 5_1_grt.log
 Found 2 errors in the logs.
     [ERROR DRT-0073] No access point for ces_1_0/io_ins_left[10].
     [ERROR DRT-0073] No access point for ces_0_0/io_ins_left[10].

My thinking is that this is already reported The-OpenROAD-Project/OpenROAD#6991

[povik]

Thanks, looks to be the same issue

[oharboe]

Not too many comments...

How about leaving src/ibex unmodified and adding a src/ibex_sv?

Those really are different test cases and it could be interesting to do an A/B comparison in the future.

[povik]

What's there to test? I don't want to support sv2v processed sources when I'm already aware of the drawbacks of that method, and it's the motivation behind yosys-slang existence. I'll let @maliberty make the call.

[oharboe]

I see. I would consider using a new folder name as it is not a new version of the same, but something completely new.

[povik]

To report here's how Ibex QoR is impacted by the switch (base: sv2v+read_verilog/test: yosys-slang)

asap7

ihp-sg13g2

nangate45

gf180

sky130hd

sky130hs

[povik]

I would consider using a new folder name as it is not a new version of the same, but something completely new.

It should be the same design in the same version with a changed flow (instead of sv2v+read_verilog we do read_slang). In any case we can put the sources into a new folder.

[jeffng-or]

@povik, we might have talked about this a while back, but I can't remember. But, can we change the flow variable SYNTH_USE_SLANG to something that could be used for both yosys-slang and Verific? In other words, something like SYNTH_SV_FRONTEND which could be yosys-slang or verific (can default to yosys-slang).

[povik]

@jeffng-or Definitely. Let me make the change

[maliberty]

I see. I would consider using a new folder name as it is not a new version of the same, but something completely new.

Is this truly something new or just the same thing in sv instead of v? I won't hold up this PR but I am unclear if this rename was needed.

[povik]

Hooray! Now we can enable asap7/cva6 in the CI. I'm not sure about the steps required.

[maliberty]

What is the runtime for asap7/cva6?

[povik]

Jeff reported 50 minutes for the full flow

[jeffng-or]

Nice! A few post-merge notes:

1. I noticed that if you build_openroad.sh twice, the following slang files get re-compiled:

[ 94%] Building CXX object src/CMakeFiles/yosys-slang.dir/abort_helpers.cc.o
[ 94%] Building CXX object src/CMakeFiles/yosys-slang.dir/async_pattern.cc.o
[ 95%] Building CXX object src/CMakeFiles/yosys-slang.dir/blackboxes.cc.o
[ 96%] Building CXX object src/CMakeFiles/yosys-slang.dir/builder.cc.o
[ 97%] Building CXX object src/CMakeFiles/yosys-slang.dir/diag.cc.o
[ 98%] Building CXX object src/CMakeFiles/yosys-slang.dir/naming.cc.o
[ 99%] Building CXX object src/CMakeFiles/yosys-slang.dir/slang_frontend.cc.o

2. nangate45/mempool_group run time is ~1h45m
3. asap7/cva6 run time is ~54m
4. I'll work with the DevOps team to get both enabled in CI

[povik]

1. I noticed that if you build_openroad.sh twice, the following slang files get re-compiled:

I confirm seeing the same on my end. I'll take a look.

[povik]

The cause is Yosys headers getting updated so yosys-slang sees it needs to recompile all the .cc which depend on them. This should be fixable inside Yosys by adjusting the install script.