This simple program: for $k (sort { length $ENV{$b} <=> length $ENV{$a} } keys %ENV) { print "$k=$ENV{$k}\n"; } Under B::Bytecode, produces correct results, then SEGVs Under B::C, produces correct results, then exits correctly. Under B::CC, produces no results, but goes into recursive doom in the sort, eventually SEGVing for lack of memory in stack death. --tom #0 0x4015825e in tcgetattr () #1 0x40158535 in tcgetattr () #2 0x40158d6b in malloc () #3 0x40061e50 in Perl_safemalloc () #4 0x40076cd3 in S_more_xpv () #5 0x40076c7c in S_new_xpv () #6 0x400775f1 in L273 () #7 0x4007adfd in Perl_sv_setpvn () #8 0x4007ddd6 in Perl_newSVpvn () #9 0x4006d160 in Perl_hv_iterkeysv () #10 0x400aa655 in Perl_do_kv () #11 0x4008926c in Perl_pp_keys () #12 0x69e0 in pp_main () at /tmp/sort.p.c:1152 #13 0x4006f719 in Perl_runops_standard () #14 0x4009b6bd in sortcv () #15 0x4009ae99 in S_qsortsv () #16 0x40093590 in Perl_pp_sort () #17 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #18 0x4006f719 in Perl_runops_standard () #19 0x4009b6bd in sortcv () #20 0x4009ae99 in S_qsortsv () #21 0x40093590 in Perl_pp_sort () #22 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #23 0x4006f719 in Perl_runops_standard () #24 0x4009b6bd in sortcv () #25 0x4009ae99 in S_qsortsv () #26 0x40093590 in Perl_pp_sort () #27 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #28 0x4006f719 in Perl_runops_standard () #29 0x4009b6bd in sortcv () #30 0x4009ae99 in S_qsortsv () #31 0x40093590 in Perl_pp_sort () #32 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #33 0x4006f719 in Perl_runops_standard () #34 0x4009b6bd in sortcv () #35 0x4009ae99 in S_qsortsv () #36 0x40093590 in Perl_pp_sort () #37 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #38 0x4006f719 in Perl_runops_standard () #39 0x4009b6bd in sortcv () #40 0x4009ae99 in S_qsortsv () #41 0x40093590 in Perl_pp_sort () #42 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #43 0x4006f719 in Perl_runops_standard () #44 0x4009b6bd in sortcv () #45 0x4009ae99 in S_qsortsv () #46 0x40093590 in Perl_pp_sort () #47 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #48 0x4006f719 in Perl_runops_standard () #49 0x4009b6bd in sortcv () #50 0x4009ae99 in S_qsortsv () #51 0x40093590 in Perl_pp_sort () #52 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #53 0x4006f719 in Perl_runops_standard () #54 0x4009b6bd in sortcv () #55 0x4009ae99 in S_qsortsv () #56 0x40093590 in Perl_pp_sort () #57 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #58 0x4006f719 in Perl_runops_standard () #59 0x4009b6bd in sortcv () #60 0x4009ae99 in S_qsortsv () #61 0x40093590 in Perl_pp_sort () #62 0x6a0f in pp_main () at /tmp/sort.p.c:1155 #63 0x4006f719 in Perl_runops_standard () [the following 25000 identical stackframes deleted]