Running test case from JDK-8253353 shows that a lot (around 400) of nested irreducible loops were created after JDK-8240576 fix.

Before JDK-8240576 I see next loops from TraceLoopOpts with only 2 IRREDUCIBLE outer loops:

Loop: N0/N0 has_call has_sfpt
  Loop: N6764/N6752 IRREDUCIBLE has_call
    Loop: N2317/N3581 IRREDUCIBLE sfpts={ 4042 5697 }
    Loop: N6785/N4367 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5860 }
    Loop: N6794/N4380 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5674 }
    Loop: N6803/N4566 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5687 }
    Loop: N6812/N4577 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5971 }
    Loop: N6821/N4722 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 6047 }

After that fix there is very long nested list of IRREDUCIBLE loops:

Loop: N0/N0 has_call has_sfpt
  Loop: N6752/N3584 IRREDUCIBLE has_call
    Loop: N6764/N3585 IRREDUCIBLE has_call
      Loop: N6776/N3586 IRREDUCIBLE has_call
        Loop: N6788/N3587 IRREDUCIBLE has_call
          Loop: N6800/N3588 IRREDUCIBLE has_call
            Loop: N6812/N3589 IRREDUCIBLE has_call
              Loop: N6824/N3590 IRREDUCIBLE has_call
                Loop: N6836/N3591 IRREDUCIBLE has_call
....
    Loop: N10592/N3581 IRREDUCIBLE
      Loop: N10604/N3580 sfpts={ 4042 5697 }
        Loop: N10614/N4367 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5860 }
        Loop: N10623/N4380 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5674 }
        Loop: N10632/N4566 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5687 }
        Loop: N10641/N4577 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 5971 }
        Loop: N10650/N4722 limit_check profile_predicated predicated counted [int,int),+1 (-1 iters) has_call has_sfpt sfpts={ 6047 }