Switching from Synlig to Yosys-Slang #3181

loglav03 · 2025-07-03T19:24:36Z

Description

Replaced Synlig/Surelog with the Yosys-Slang plugin for Yosys for reading SystemVerilog.

Yosys-Slang is installed by default in the build system and depends on Yosys. To use Yosys-Slang as the parser instead of the default Yosys parser, add the '-parser slang' option at the end of your 'run_vtr_flow.py <circuit> <arch>' or add it to the script parameters in the config file for regression test suites.

Yosys-Slang can be used to parse both verilog and SystemVerilog but may require specific syntax when parsing with verilog.

If you disable the cmake param "-DWITH_PARMYS" you should also disable the "-DSLANG_SYSTEMVERILOG" param as well to avoid cmake errors.

Related Issue

Motivation and Context

Synlig has a lot of overhead when building with the vtr build system leading to issues when building in CI and sometimes locally. Synlig is also poorly maintained. Yosys-Slang has significantly less overhead, can easily be implemented as a plugin for yosys, and is regularly maintained.

How Has This Been Tested?

Has been tested with the vtr_reg_system_verilog tests [PASSED]

Types of changes

[ x] Bug fix (change which fixes an issue)
New feature (change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

[ x] My change requires a change to the documentation
[ x] I have updated the documentation accordingly
[ x] I have added tests to cover my changes
[ x] All new and existing tests passed

…stall with vtr when enabled with the cmake parameter -DSLANG_SYSTEMVERILOG=ON

…ultiple .sv files instead of single flattened .sv files (with the exception of the f4pga_pulse_width_led test since it uses .v files instead of .sv)

…ssion Test

…oaded in when not enabled.

…ts in test.yml

…log with yosys-slang

loglav03 · 2025-07-08T20:23:36Z

@petergrossmann21 - I ran tests with yosys-slang enabled on the benchmarks you listed in this PR #2885. Some of these benchmarks made it through the entire flow and passed while others failed at read_slang in Yosys or failed at the VPR stage. There are also many other benchmarks not in the list that also failed with yosys-slang. Whenever you're available Peter I'll need help with HDL file cleanup for this.

Passing VPR Benchmarks:

blob_merge
diffeq1
diffeq2
single_ff
single_wire

Failing VPR Benchmarks:

and_latch
arm_core
boundtop
ch_intrinisics
multiclock_output_and_latch
multiclock_reader_writer
multiclock_separate_and_latch
stereovision3

I have not tried koios yet since the benchmarks take a long time to run, but I'm sure I will see similar results.

…ng in synthesis.tcl to another .tcl (slang_filelist.tcl) to make synthesis.tcl more readable

…system. Updated golden results for SystemVerilog reg tests

AlexandreSinger

HI @loglav03 thank you so much for this PR! The CI test you added is exactly what I had in mind. Great job!

Some comments below.

.github/workflows/test.yml

CMakeLists.txt

libs/EXTERNAL/CMakeLists.txt

AlexandreSinger · 2025-07-10T20:53:19Z

libs/EXTERNAL/CMakeLists.txt

-
-            # Ensure dependencies like Yosys are built first
-            DEPENDS yosys  # Ensure submodule sync runs before synlig build
+            BUILD_COMMAND ${CMAKE_COMMAND} --build ${SLANG_BUILD_DIR} -- -j${PROCESSOR_COUNT}


"-j${PROCESSOR_COUNT}" should not be set here. The number of threads is enhereted by the make that creates it. I think this should not be here. This can have some odd affects. This is what is causing this warning:

It actually uses -j1 if I remove the "-j${PROCESSOR_COUNT}". I get this when I remove it:
gmake[4]: warning: jobserver unavailable: using -j1. Add '+' to parent make rule.

AlexandreSinger · 2025-07-10T20:54:32Z

libs/EXTERNAL/CMakeLists.txt

+            SOURCE_DIR ${SLANG_SRC_DIR}
+            BINARY_DIR ${SLANG_BUILD_DIR}
+
+            #Disabling UndrivenPass in slang_frontend.cc


Could you add some more comments here as to why we need to patch slang. Is this something that we can bring back to the slang master? Or is there something integral to VTR that causes problems?

I currently have it patching slang to disable the UndrivenPass because it was failing benchmarks due to unsupported synchronous rules in vtr_primitives.v and wouldn't let me run any benchmark with read_slang without disabling that pass.

I believe Peter is working on this in his work to clean up benchmarks to be compatible with read_slang. So if that ends up being fixed, I'll probably be able to remove the patch step for slang. I think we can leave this in for now just so the CI is able to pass the SystemVerilog reg test.

libs/EXTERNAL/patch_slang.cmake

vtr_flow/tasks/regression_tests/vtr_reg_system_verilog/task_list.txt

… off

…ated golden results

AlexandreSinger

Thank you for resolving my prior comments! I appreciate it. This PR is looking very close to being able to be merged. I just have two final comments:

First, regarding the "-j" issue. When you remove it, it was asking you to prefix your call to the make subprocess with "+". So that would look like BUILD_COMMAND +${CMAKE_COMMAND} .... This should enable the job server of our CMake to communicate with the sub-cmake that you are calling. I wonder if this is the cause of the multiple builds we are seeing for the Yosys build? May be worth looking into. But for this PR, can you please remove the -j... option and prepend the build command with +. I want to avoid confusing warnings from showing up to users of VTR.

Second, thank you for adding back the koios SV regression test. It is actually very common to forget this. I actually made a CI test to check for this type of thing automatically. I only have it run on currently run test suites. Can you please add vtr_reg_system_verilog to this config file:

vtr-verilog-to-routing/dev/vtr_test_suite_verifier/test_suites_info.json

Lines 14 to 17 in a8e0002

    
           { 
        
               "name": "vtr_reg_valgrind_small", 
        
               "ignored_tasks": [] 
        
           },

I do not think you need to mark any tests as ignored, so you can just copy the entry for vtr_reg_valgrind_small

…stem_verilog to vtr test suite verifier

…ocation

loglav03 · 2025-07-14T16:51:48Z

@AlexandreSinger All comments should be resolved now! Simply adding a + to the build_command for slang didn't work so I had to find a workaround for it. It should be inheriting threads properly now without emitting a warning.

AlexandreSinger

LGTM

loglav03 and others added 5 commits June 26, 2025 17:38

Added in yosys-slang as a submodule and configured it to build and in…

4f8abac

…stall with vtr when enabled with the cmake parameter -DSLANG_SYSTEMVERILOG=ON

Set up yosys-slang to be used as a frontend for Yosys

efb1d87

Fully implemented yosys-slang as a plugin for yosys

90e180b

Updating configs for vtr_reg_system_verilog tests. They now read in m…

c1c2a5d

…ultiple .sv files instead of single flattened .sv files (with the exception of the f4pga_pulse_width_led test since it uses .v files instead of .sv)

Merge branch 'master' into synlig_to_yosys_slang

7c4c868

github-actions bot added lang-cpp C/C++ code build Build system lang-python Python code lang-make CMake/Make code external_libs labels Jul 3, 2025

Adding SystemVerilog reg test to CI

0152c36

github-actions bot added the infra Project Infrastructure label Jul 3, 2025

loglav03 added 10 commits July 3, 2025 17:31

Trying to fix issue with install dependencies for SystemVerilog Regre…

f7ae912

…ssion Test

Fixing regression test run failures due to yosys-slang plugin being l…

81b7ee4

…oaded in when not enabled.

Fixing code format in python script (python.cc) and resolving conflic…

ce26e71

…ts in test.yml

Further resolving conflicts with test.yml

d2ffe14

Further resolving conflicts with test.yml

172758b

Merge branch 'master' into synlig_to_yosys_slang

0b1d2c0

Fixing line format errors in parmys.cc

9b51cbc

Further fixing line format/length errors in parmys.cc

8d8d683

Further fixing line format/length errors in parmys.cc

2d107fb

Updating parser documentation for run_vtr_flow to replace synlig/sure…

3cf1050

…log with yosys-slang

github-actions bot added the docs Documentation label Jul 7, 2025

loglav03 added 6 commits July 8, 2025 17:24

Cleaning up some code in synthesis.tcl

3fbe39f

Further cleaning up code and adding some comments

56b7a7d

Split the file extension checking and filelist building for yosys sla…

9383300

…ng in synthesis.tcl to another .tcl (slang_filelist.tcl) to make synthesis.tcl more readable

Removed commented out cmake option for SYNLING_SYSTEMVERILOG

b842759

Added SystemVerilog CI test. Enabled yosys-slang by default in build …

1d7a5cb

…system. Updated golden results for SystemVerilog reg tests

Disabling yosys-slang whenever parmys is disabled.

7f6749c

loglav03 marked this pull request as ready for review July 10, 2025 20:31

loglav03 requested review from AlexandreSinger and amirarjmand93 July 10, 2025 20:32

AlexandreSinger requested changes Jul 10, 2025

View reviewed changes

petergrossmann21 mentioned this pull request Jul 10, 2025

Resolve slang errors in VTR benchmarks #3195

Open

7 tasks

loglav03 changed the title ~~[WIP] Switching from Synlig to Yosys-Slang~~ Switching from Synlig to Yosys-Slang Jul 11, 2025

loglav03 added 6 commits July 11, 2025 10:45

Cleaned up compilation handling for yosys-slang when parmys is turned…

ff0795c

… off

Suppressing warnings in yosys-slang and yosys

a4090df

Attempting to further suppress warnings for yosys-slang build

09d5e6f

Attempting to further suppress warnings for yosys-slang build

787af05

Added header explanation to patch_slang.cmake

341a972

Added koios_sv/deepfreeze.style1.sv to vtr_reg_system_verilog and cre…

0cda1bf

…ated golden results

AlexandreSinger requested changes Jul 11, 2025

View reviewed changes

loglav03 added 3 commits July 14, 2025 11:58

Fixed enherited threads issue with yosys-slang build

6d7abd0

Attempting to suppress warnings for slang again, and added vtr_reg_sy…

3bcef9a

…stem_verilog to vtr test suite verifier

Fixed build issue with yosys-slang not installing plugin in correct l…

ddd28fa

…ocation

loglav03 added 7 commits July 14, 2025 14:17

Further attempting to suppress build warnings for yosys-slang

88d2b5c

Further attempting to suppress build warnings for yosys-slang

d447f4a

Further attempting to suppress build warnings for yosys-slang

42c7d0e

Further attempting to suppress build warnings for yosys-slang

dfe45d2

Further attempting to suppress build warnings for yosys-slang

5c78ad6

Removing unused variable for yosys-slang build

ceb49e1

Turning LOG_BUILD off for yosys-slang build to avoid cmake errors

52431fb

AlexandreSinger approved these changes Jul 14, 2025

View reviewed changes

Merge branch 'master' into synlig_to_yosys_slang

3b2c0a8

AlexandreSinger mentioned this pull request Jul 14, 2025

[CI] Added System Verilog Regression Tests to GitHub Runners #2885

Closed

AlexandreSinger merged commit 3ad299e into master Jul 14, 2025
30 checks passed

AlexandreSinger deleted the synlig_to_yosys_slang branch July 14, 2025 21:24

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Switching from Synlig to Yosys-Slang #3181

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loglav03 commented Jul 3, 2025 •

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Switching from Synlig to Yosys-Slang #3181

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Description

Related Issue

Motivation and Context

How Has This Been Tested?

Types of changes

Checklist:

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