OSS CAD suite apparently distributing stale (broken) build

[Slaats7]

Hi,

I am fairly new to Yosys, so far I have only read Verilog files. Now I would like to read SystemVerilog files with this plugin. However I cannot get a basic example like the fifo below to be read. I wonder if anyone could help or point me in some direction.

yosys> debug read_slang ../rtl/design/test/fifo.v --top fifo -D DEBUG

1. Executing SLANG frontend.
Adding clk (Variable)
Adding rst (Variable)
Adding wrdata_i (Variable)
Adding wr_i (Variable)
Adding rddata_o (Variable)
Adding rd_i (Variable)
Adding s_mem_flat (Variable)
Adding s_wr_ptr (Variable)
Adding s_rd_ptr (Variable)
ERROR: Exception: vector::_M_range_check: __n (which is 0) >= this->size() (which is 0)

The file does compile in the slang explorer: https://sv-lang.com/explore/

fifo.v:

module fifo (
    input logic clk,
    input logic rst,
    input logic [7:0] wrdata_i,
    input logic wr_i,
    output logic [7:0] rddata_o,
    input logic rd_i
);

    logic [127:0] s_mem_flat; // DEPTH=16, WIDTH=8
    logic [3:0] s_wr_ptr, s_rd_ptr; // PTR_WIDTH=4

    always_ff @(posedge clk or negedge rst) begin
        if (!rst) begin
            s_mem_flat <= '0;
        end else if (wr_i) begin
            s_mem_flat[(s_wr_ptr * 8) +: 8] <= wrdata_i;
        end
    end

    always_ff @(posedge clk) begin
        if (rd_i) begin
            rddata_o <= s_mem_flat[(s_rd_ptr * 8) +: 8];
        end
    end
endmodule

Is there something we should be doing different? Any help would be great. Thanks in advance.

[povik]

No, this is a clear bug in the plugin. Thanks for reporting

[povik]

So far I haven't been able to reproduce, your example reads OK for me locally. Can you share how have you obtained the slang plugin, and what platform you are running on?

[Slaats7]

I am using the OSS CAD Suite (oss-cad-suite-linux-x64-20241223.tgz) and running on Linux Mint 22.

[povik]

I tried enabling libc++ assertions on macOS but couldn't reproduce still. I will see about reproducing on Linux.

[Slaats7]

What version of Yosys are you using? I have built Yosys and this plugin from source and now the example reads OK. I did need to use an older version of Yosys (0.43+11).

[povik]

That’s a good clue. I am testing against a recentish version (I don’t have the number at hand)

[povik]

I am using the OSS CAD Suite (oss-cad-suite-linux-x64-20241223.tgz) and running on Linux Mint 22.

The CAD suite should had a nightly version of Yosys, so that's in conflict with this issue only showing on older Yosys.

[Slaats7]

I am using the OSS CAD Suite (oss-cad-suite-linux-x64-20241223.tgz) and running on Linux Mint 22.

The CAD suite should had a nightly version of Yosys, so that's in conflict with this issue only showing on older Yosys.

I don't understand your comment. The CAD suite contained Yosys 0.48+45. When building from source, I had to downgrade Yosys to version 0.43+11.

[povik]

OK, thanks for the clarification

[Slaats7]

Idk if its related, but building the plugin with a newer version of Yosys (0.48+45) does not work for me. Building with the older version (0.43+11) works fine and can read the example.

$ make -j$(nproc)

    CXX build/abort_helpers.o

    CXX build/async_pattern.o

    CXX build/blackboxes.o

    CXX build/builder.o

    CXX build/slang_frontend.o

    CXX build/naming.o

In file included from src/builder.cc:7:

src/slang_frontend.h:173:60: error: ‘hash_ptr_ops’ is not a member of ‘Yosys’; did you mean ‘hash_ops’?

  173 |         Yosys::dict<const ast::Scope*, std::string, Yosys::hash_ptr_ops> scopes_remap;

      |                                                            ^~~~~~~~~~~~

      |                                                            hash_ops

src/slang_frontend.h:173:72: error: template argument 3 is invalid

  173 |         Yosys::dict<const ast::Scope*, std::string, Yosys::hash_ptr_ops> scopes_remap;

      |                                                                        ^

src/slang_frontend.h:173:16: error: ‘<expression error>’ in namespace ‘Yosys’ does not name a type

  173 |         Yosys::dict<const ast::Scope*, std::string, Yosys::hash_ptr_ops> scopes_remap;

      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[povik]

That shouldn't be related (it's due to an API change from YosysHQ/yosys#4524)

[povik]

Err, I missed your point about this being the same Yosys version as the CAD suite. How come it builds for the CAD suite, I wonder?

[povik]

Idk if its related, but building the plugin with a newer version of Yosys (0.48+45) does not work for me.

So this turned out to be spot on. The last successful build of yosys-slang within CAD suite is

https://github.com/YosysHQ/oss-cad-suite-build/actions/runs/12385464988/job/34571757331

and it's been failing ever since, e.g.

https://github.com/YosysHQ/oss-cad-suite-build/actions/runs/12541062019/job/34969099348

I guess that means the CAD suite packages a stale version of the plugin, which is the likely cause of the original error.

[Slaats7]

Why should this problem be limited to just the CAD suite? Doesn't this mean that the plugin can't be built with Yosys versions that have this API change?

That shouldn't be related (it's due to an API change from YosysHQ/yosys#4524)

Therefore it will only work with older Yosys versions and the suite builds fail because they use a version with that API change?

[povik]

Yes, there are two issues: (1) the plugin needs to be updated for the API change (a trivial change) and (2) OSS CAD suite distributes stale builds if the build fails

[povik]

I pushed a2e91d4 which might do the trick

[Slaats7]

That did not work

/usr/local/share/yosys/include/kernel/hashlib.h:848:36: error: ‘const struct Yosys::hashlib::hash_ptr_ops’ has no member named ‘hash’
  848 |                         hash = ops.hash(key).yield() % (unsigned int)(hashtable.size());
      |                                ~~~~^~~~

[dpetrisko]

Hi, also running into this (directed here from searching the error :)). Just curious, is the intention for yosys-slang master to build with yosys master or is there some other versioning matrix I should follow for compatibility?

[povik]

It should build and work fine with the last few yosys releases, including the latest. I think I will document this and make the CI validate it. Building with yosys master is a moving target so I can't assure it.

[povik]

Building with yosys master is a moving target so I can't assure it.

This is fundamentally at odds with the nightly releasing of OSS CAD suite so something for the Yosys team to discuss.

[povik]

Second attempt at fixing the build against pre-release Yosys in 1b19302

[Slaats7]

That did the trick. The plugin builds successful within the CAD suite:
https://github.com/YosysHQ/oss-cad-suite-build/actions/runs/12566168170/job/35031269381

[povik]

I hope this is fixed. We can re-open if there's an issue still.