vsc.model.solve_failure.SolveFailure: solve failure [randomly] in riscv-dv

[kkmonk]

• run cmd: python3 run.py --simulator=pyflow --test riscv_rand_instr_test -v
• yaml:

- test: riscv_rand_instr_test
  description: >
    Random instruction stress test
  iterations: 1
  gen_test: riscv_instr_base_test
  gen_opts: >
    +instr_cnt=100
    +no_data_page=1
    +num_of_sub_program=0
    +bare_program_mode=1
    +directed_instr_0=riscv_load_store_rand_instr_stream,50
    +directed_instr_1=riscv_load_store_hazard_instr_stream,50
    +directed_instr_2=riscv_int_numeric_corner_stream,50
    +directed_instr_3=riscv_single_load_store_instr_stream,20
    +directed_instr_4=riscv_jal_instr,20
    +directed_instr_5=riscv_load_store_stress_instr_stream,20
  rtl_test: core_base_test

• stack info

Thu, 24 Feb 2022 16:59:05 lib.py:131   DEBUG    Traceback (most recent call last):
  File "/home/xuelai/riscv-dv/pygen/pygen_src/test/riscv_instr_base_test.py", line 38, in run
    self.run_phase(1)
  File "/home/xuelai/riscv-dv/pygen/pygen_src/test/riscv_instr_base_test.py", line 66, in run_phase
    self.asm.gen_program()
  File "/home/xuelai/riscv-dv/pygen/pygen_src/riscv_asm_program_gen.py", line 105, in gen_program
    self.generate_directed_instr_stream(hart=hart,
  File "/home/xuelai/riscv-dv/pygen/pygen_src/riscv_asm_program_gen.py", line 1131, in generate_directed_instr_stream
    new_instr_stream.randomize()
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/rand_obj.py", line 171, in randomize
    raise e
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/rand_obj.py", line 162, in randomize
    Randomizer.do_randomize(
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/model/randomizer.py", line 607, in do_randomize
    fm.post_randomize()
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/model/field_composite_model.py", line 148, in post_randomize
    self.rand_if.do_post_randomize()
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/rand_obj.py", line 291, in do_post_randomize
    self.post_randomize()
  File "/home/xuelai/riscv-dv/pygen/pygen_src/riscv_load_store_instr_lib.py", line 117, in post_randomize
    self.add_mixed_instr(self.num_mixed_instr)
  File "/home/xuelai/riscv-dv/pygen/pygen_src/riscv_directed_instr_lib.py", line 89, in add_mixed_instr
    instr = self.randomize_instr(instr)
  File "/home/xuelai/riscv-dv/pygen/pygen_src/riscv_instr_stream.py", line 239, in randomize_instr
    instr = self.randomize_gpr(instr)
  File "/home/xuelai/riscv-dv/pygen/pygen_src/riscv_instr_stream.py", line 263, in randomize_gpr
    instr.rs1 != cfg.reserved_regs[i]
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/rand_obj.py", line 271, in __exit__
    raise e
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/rand_obj.py", line 261, in __exit__
    Randomizer.do_randomize(
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/model/randomizer.py", line 597, in do_randomize
    r.randomize(ri, bounds_v.bound_m)
  File "/home/xuelai/riscv-dv/dv_env/lib/python3.8/site-packages/vsc/model/randomizer.py", line 211, in randomize
    raise SolveFailure(
vsc.model.solve_failure.SolveFailure: solve failure
Problem Set: 2 constraints
  <unknown>:
    if ((instr_name == 242)) {
    (rd == 2);
}
  <unknown>:
    if (has_rd) {
    (rd != reserved_rd.reserved_rd[0]);
}

Problem Set: 2 constraints
  <unknown>:
    if ((instr_name == 242)) {
    (rd == 2);
}
  <unknown>:
    if (has_rd) {
    (rd != reserved_rd.reserved_rd[0]);
}

related code:

instr_name == 242 occurs everytime ,but I don't know where it comes from.