Bug of pso technique. ValueError: min() arg is an empty sequence

[gloaming2dawn]

I am using PSO_GA_Bandit to find a good pass sequence for perlin.c in llvm-test-suite (test-suite/SingleSource/Benchmarks/Misc/perlin.c). I am using llvm 10.0.1.

To get a statistical results, I run the tuner for one hundred of times (I set --test-limit=1000), the error occurred:
Traceback (most recent call last):
File "/nobackup/scjzh/codesize/Tuner_Codesize.py", line 194, in
FlagsTuner.main(args,Oz_compile_time,Oz_codesize,O0_codesize)
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/measurement/interface.py", line 301, in main
return TuningRunMain(cls(args, *pargs, **kwargs), args).main()
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/tuningrunmain.py", line 201, in main
self.search_driver.main()
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/driver.py", line 272, in main
if self.run_generation_techniques() > 0:
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/driver.py", line 172, in run_generation_techniques
dr = self.root_technique.desired_result()
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/metatechniques.py", line 43, in desired_result
dr = technique.desired_result()
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/technique.py", line 93, in desired_result
cfg = self.desired_configuration()
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/technique.py", line 201, in desired_configuration
return next(self.gen)
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/technique.py", line 255, in call_main_generator
p = next(subgen)
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/pso.py", line 45, in main_generator
if objective.lt(config(particle.position), config(particle.best)):
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/objective.py", line 75, in lt
return self.compare(a, b) < 0
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/objective.py", line 62, in compare
return self.config_compare(a, b)
File "/home/home02/scjzh/.local/lib/python3.9/site-packages/opentuner/search/objective.py", line 176, in config_compare
return cmp(min(list(map(_.time, self.driver.results_query(config=config1)))),
ValueError: min() arg is an empty sequence

This error is accidental. If you run the tuner only once, everything is ok. But if you run many times, error may occur.
I have attached perlin.bc (unoptimized IR of perlin.c), sequence_Oz_llvm10.txt (passes I used) and the tuner.

tuner.zip