Dual port RAM ghdl-yosys-plugin yosys assertion error

[JulianKemmerer]

Description I am hitting this assertion and erroring out https://github.com/YosysHQ/yosys/blob/41b34a19353dbbe00aa08f3561e25e0bfa4c84d2/kernel/mem.cc#L473C5-L473C33

if ((port.transparency_mask[j] || port.collision_x_mask[j]) && !wport.removed) {
                log_assert(port.clk_enable);

This is when trying to convert some VHDL->Verilog (using ghdl plugin front end) I think it has to do with how the HDL describes a dual port ram? (does successfully map to Xilinx BRAMs)

Expected behaviour No assertion error.

How to reproduce?

cd ram_error
bash top/convert_to_verilog.sh

convert_to_verilog.sh:

/usr/local/bin/ghdl -i --std=08 -frelaxed `cat vhdl_files.txt`
/usr/local/bin/ghdl -m --std=08 -frelaxed top 
/usr/local/bin/yosys -g -m ghdl  -p "ghdl --std=08 -frelaxed top;  write_verilog top.v"

output snippet:

./main.c/the_ram/the_ram_0CLK_b45f1687.vhd:31:19:warning: type of a shared variable must be a protected type [-Wshared]
  shared variable the_ram : ram_t := (others => (others => '0')); 
                  ^
...

-- Running command `ghdl --std=08 -frelaxed top;  write_verilog top.v' --

1. Executing GHDL.
./main.c/the_ram/the_ram_0CLK_b45f1687.vhd:31:19:note: found RAM "the_ram", width: 8 bits, depth: 19200
  shared variable the_ram : ram_t := (others => (others => '0')); 
                  ^
Importing module top.
Importing module main_0clk_88c0218f.
Importing module the_ram_0clk_b45f1687.

2. Executing Verilog backend.

2.1. Executing BMUXMAP pass.

2.2. Executing DEMUXMAP pass.
ERROR: Assert `port.clk_enable' failed in kernel/mem.cc:473.

Context GHDL 4.0.0-dev (3.0.0.r448.g2245a7fd1) [Dunoon edition]

Yosys 0.32+76 (git sha1 73cb4977b, clang 10.0.0-4ubuntu1 -fPIC -Os)

Yosys dev said this is an issue with how GHDL is emitting the RAM... :shrug:

Does this have to do with the relaxed-to-warning shared variable must be a protected type error?

Thanks for your time

ram_error.zip

[tgingold]

I will investigate, but if you simply need to convert from vhdl to verilog, you don't need yosys. You can simply do:

ghdl synth --out=verilog FILES -e

[JulianKemmerer]

Thank you for considering looking into this.

I did indeed forget that GHDL alone can convert to Verilog! I will absolutely try this :fist_raised: However, I feel like I once heard that the path through Yosys is generally 'better' for producing verilog - without details on what that means? I suppose we'll see :nerd_face: