Use of blocking assignments in always_ff block

DSIM is reporting the use of blocking assignments within an always_ff block in file riscv_tracer.sv. I do not see this warning with xrun, but inspection shows it to be a real item. Details below:

URL: https://github.com/openhwgroup/cv32e40p Branch: master Hash: de826243 Path: rtl/riscv_tracer.sv, lines 744..750.

  // cycle counter
  always_ff @(posedge clk, negedge rst_n)
  begin
    if (rst_n == 1'b0)
      cycles = 0;
    else
      cycles = cycles + 1;
  end

To Reproduce:

Run the comp rule (clones the RTL, compiles, and quits).

$ git clone https://github.com/openhwgroup/core-v-verif
$ cd core-v-verif/cv32/sim/uvmt_cv32
$ make SIMULATOR=dsim comp