D::S also uses AvARRAY, AvALLOC and AvARYLEN.

use strict;
use warnings;

use Devel::Peek qw( Dump );

use Inline C => <<'__EOI__';
void call_AvMAX(AV* av)    { AvMAX(av);    }
void call_AvARRAY(AV* av)  { AvARRAY(av);  }
void call_AvALLOC(AV* av)  { AvALLOC(av);  }
void call_AvARYLEN(AV* av) { AvARYLEN(av); }
__EOI__

my @a = qw( a b c );  print("After init:\n");        Dump(\@a, 1);
call_AvMAX(\@a);      print("\nAfter AvMAX:\n");     Dump(\@a, 1);
call_AvARRAY(\@a);    print("\nAfter AvARRAY:\n");   Dump(\@a, 1);
call_AvALLOC(\@a);    print("\nAfter AvALLOC:\n");   Dump(\@a, 1);
call_AvARYLEN(\@a);   print("\nAfter AvARYLEN:\n");  Dump(\@a, 1);
[download]

After init:
SV = RV(0x238c18) at 0x238c0c
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x182a68c
  SV = PVAV(0x2399f4) at 0x182a68c
    REFCNT = 2
    FLAGS = (PADMY)
    ARRAY = 0x1824504
    FILL = 2
    MAX = 3
    ARYLEN = 0x0
    FLAGS = (REAL)

After AvMAX:
SV = RV(0x238c18) at 0x238c0c
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x182a68c
  SV = PVAV(0x2399f4) at 0x182a68c
    REFCNT = 2
    FLAGS = (PADMY)
    ARRAY = 0x1824504
    FILL = 2
    MAX = 3
    ARYLEN = 0x0
    FLAGS = (REAL)

After AvARRAY:
SV = RV(0x238c18) at 0x238c0c
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x182a68c
  SV = PVAV(0x2399f4) at 0x182a68c
    REFCNT = 2
    FLAGS = (PADMY)
    ARRAY = 0x1824504
    FILL = 2
    MAX = 3
    ARYLEN = 0x0
    FLAGS = (REAL)

After AvALLOC:
SV = RV(0x238c18) at 0x238c0c
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x182a68c
  SV = PVAV(0x2399f4) at 0x182a68c
    REFCNT = 2
    FLAGS = (PADMY)
    ARRAY = 0x1824504
    FILL = 2
    MAX = 3
    ARYLEN = 0x0
    FLAGS = (REAL)

After AvARYLEN:
SV = RV(0x238c18) at 0x238c0c
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x182a68c
  SV = PVAV(0x2399f4) at 0x182a68c
    REFCNT = 2
    FLAGS = (PADMY,RMG)
    MAGIC = 0x23fdbc
      MG_VIRTUAL = &PL_vtbl_arylen_p
      MG_TYPE = PERL_MAGIC_arylen_p(@)
      MG_FLAGS = 0x02
        REFCOUNTED
    ARRAY = 0x1824504
    FILL = 2
    MAX = 3
    ARYLEN = 0x0
    FLAGS = (REAL)
[download]

So AvARYLEN is the culprit. In 5.10.1, AvARYLEN is defined as

#define AvARYLEN(av)    (*Perl_av_arylen_p(aTHX_ MUTABLE_AV(av)))
[download]

Sounds familiar.