VHPI: Not able to map type (vhpiSubtypeDeclK) 1079 to object

[bohrax]

When using nvc together with cocotb I get this error when using ports/signals with e.g. natural or positive datatypes. It works when declaring them as integers. Not sure if the problem lies within nvc or cocotb, or if it is expected at all?

nvc version 1.18.0 and cocotb 1.9.2 on Ubuntu 20.04 amd64.

------------------------------------------------------------------------------------------------------------------------------------------------------------------- Captured log call -------------------------------------------------------------------------------------------------------------------------------------------------------------------
INFO     cocotb:simulator.py:295 Running command: nvc --work=module -L /home/bohre/workspace/fpga/core/cocotb/nvc_test_tb/sim_build/test_module -a /home/bohre/workspace/fpga/core/cocotb/nvc_test_tb/module.vhd
INFO     cocotb:simulator.py:295 Running command: nvc --work=module -L /home/bohre/workspace/fpga/core/cocotb/nvc_test_tb/sim_build/test_module -e module
INFO     cocotb:simulator.py:295 Running command: nvc --work=module -L /home/bohre/workspace/fpga/core/cocotb/nvc_test_tb/sim_build/test_module --stderr=error -r module --load /home/bohre/workspace/fpga/core/venv_192/python3/lib/python3.8/site-packages/cocotb/libs/libcocotbvhpi_nvc.so --wave=module.fst
INFO     cocotb:simulator.py:266 ** Note: loading VHPI plugin /home/bohre/workspace/fpga/core/venv_192/python3/lib/python3.8/site-packages/cocotb/libs/libcocotbvhpi_nvc.so
INFO     cocotb:simulator.py:266      -.--ns INFO     gpi                                ..mbed/gpi_embed.cpp:108  in set_program_name_in_venv        Using Python virtual environment interpreter at /home/bohre/workspace/fpga/core/venv/python3/bin/python
INFO     cocotb:simulator.py:266      -.--ns INFO     gpi                                ../gpi/GpiCommon.cpp:101  in gpi_print_registered_impl       VHPI registered
INFO     cocotb:simulator.py:266      0.00ns INFO     cocotb                             Running on nvc version 1.18.0
INFO     cocotb:simulator.py:266      0.00ns INFO     cocotb                             Running tests with cocotb v1.9.2 from /home/bohre/workspace/fpga/core/venv/python3/lib/python3.8/site-packages/cocotb
INFO     cocotb:simulator.py:266      0.00ns INFO     cocotb                             Seeding Python random module with 1759301748
INFO     cocotb:simulator.py:266      0.00ns INFO     cocotb.regression                  Found test test_module.minimal
INFO     cocotb:simulator.py:266      0.00ns INFO     cocotb.regression                  running minimal (1/1)
INFO     cocotb:simulator.py:266      0.00ns ERROR    gpi                                VHPI: Not able to map type (vhpiSubtypeDeclK) 1079 to object
INFO     cocotb:simulator.py:266      0.00ns INFO     cocotb.regression                  minimal failed
INFO     cocotb:simulator.py:266                                                         Traceback (most recent call last):
INFO     cocotb:simulator.py:266                                                           File "/home/bohre/workspace/fpga/core/cocotb/nvc_test_tb/test_module.py", line 29, in minimal
INFO     cocotb:simulator.py:266                                                             dut.di.value = 1
INFO     cocotb:simulator.py:266                                                           File "/home/bohre/workspace/fpga/core/venv/python3/lib/python3.8/site-packages/cocotb/handle.py", line 370, in __getattr__
INFO     cocotb:simulator.py:266                                                             raise AttributeError(f"{self._name} contains no object named {name}")
INFO     cocotb:simulator.py:266                                                         AttributeError: MODULE contains no object named di
INFO     cocotb:simulator.py:266      0.00ns INFO     cocotb.regression                  **************************************************************************************
INFO     cocotb:simulator.py:266                                                         ** TEST                          STATUS  SIM TIME (ns)  REAL TIME (s)  RATIO (ns/s) **
INFO     cocotb:simulator.py:266                                                         **************************************************************************************
INFO     cocotb:simulator.py:266                                                         ** test_module.minimal            FAIL           0.00           0.00          0.00  **
INFO     cocotb:simulator.py:266                                                         **************************************************************************************
INFO     cocotb:simulator.py:266                                                         ** TESTS=1 PASS=0 FAIL=1 SKIP=0                  0.00           0.06          0.00  **
INFO     cocotb:simulator.py:266                                                         **************************************************************************************
INFO     cocotb:simulator.py:266 
INFO     cocotb:simulator.py:266 ** Note: 1fs+0: VHPI plugin requested end of simulation
ERROR    cocotb:simulator.py:217 Failed: test_module::minimal

The vhdl code:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;


entity module is
    port (
        clk:    in std_logic;
        reset:  in std_logic;
        di:     in natural range 0 to 1;
        do:     out natural range 0 to 1
    );
end entity module;


architecture rtl of module is
begin
    process (clk)
    begin
        if rising_edge(clk) then
            if reset = '1' then
                do <= 0;
            else
                do <= di;
            end if;
        end if;
    end process;
end architecture rtl;

The cocotb testbench:

import cocotb
import cocotb.clock
import cocotb.triggers
import pytest

testcases = [
    "minimal",
]


@pytest.mark.parametrize("testcase", testcases)
def test_module(cocotb_runner, testcase):
    cocotb_runner.vhdl_sources = [
        'module.vhd',
    ]
    cocotb_runner.testcase = testcase
    cocotb_runner.run()


@cocotb.test()
async def minimal(dut):
    c = cocotb.clock.Clock(dut.clk, 10, 'ns')
    cocotb.start_soon(c.start())

    dut.reset.value = 1
    await cocotb.triggers.RisingEdge(dut.clk)
    dut.reset.value = 0

    dut.di.value = 1
    await cocotb.triggers.RisingEdge(dut.clk)
    await cocotb.triggers.FallingEdge(dut.clk)

    assert dut.do.value == 1

[nickg]

This seems like a bug: vhpi_get(vhpiBaseType, ..) returns the wrong thing when you have a subtype like natural with an additional constraint.

[bohrax]

Thanks! In that case I'll let the cocotb people know that the cause is most likely on the nvc side. Would you like me to create an issue from this conversation?

[nickg]

Should be fixed in 14f8f7c

[bohrax]

Excellent! Can confirm that this solves the issue.