[Bug bootstrap/44469] [4.5/4.6 Regression] internal compiler error: in fixup_reorder_chain, at cfglayout.c:797
--- Comment #3 from jakub at gcc dot gnu dot org 2010-06-09 13:55 --- There are more issues: 1) cleanup_barriers seems to do weird things with these empty bbs from __builtin_unreachable (), I guess it shouldn't reorder anything if prev is a LABEL_P 2) the reason why this compiles fine on x86_64 seems to be in different bb reordering. On arm the empty bb is reordered after the condjump, which means its label is deleted by /* Remove code labels no longer used. */ in try_optimize_cfg and then the block is trivially empty. On x86_64 we don't ICE, but generate useless code: movl(%rdi), %eax testl %eax, %eax je .L2 cmpl$1, %eax jne .L3 movq%rdi, %rsi .L2: xorl%eax, %eax cmpb$0, (%rsi) sete%al ret .L3: .cfi_endproc I'd say we shouldn't try to delete just trivially_empty_bb_p's, but also ones that before the bb note also have labels and after it nothing or only DEBUG_INSNs, but we should delete only if we actually succeed adjusting the jump insn at the end of the earlier block. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44469
[Bug bootstrap/44469] [4.5/4.6 Regression] internal compiler error: in fixup_reorder_chain, at cfglayout.c:797
--- Comment #2 from jakub at gcc dot gnu dot org 2010-06-09 12:51 --- I guess for empty bbs with no successor where the predecessor ends in an conditional jump without side-effects try_optimize_cfg can't do just delete_basic_block, but needs to call some function to actually adjust the conditional jump into unconditional. Perhaps try_redirect_by_replacing_jump or something similar. -- jakub at gcc dot gnu dot org changed: What|Removed |Added CC||hubicka at gcc dot gnu dot ||org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44469
[Bug bootstrap/44469] [4.5/4.6 Regression] internal compiler error: in fixup_reorder_chain, at cfglayout.c:797
-- rguenth at gcc dot gnu dot org changed: What|Removed |Added Target Milestone|--- |4.5.1 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44469
[Bug bootstrap/44469] [4.5/4.6 Regression] internal compiler error: in fixup_reorder_chain, at cfglayout.c:797
--- Comment #1 from siarhei dot siamashka at gmail dot com 2010-06-08 14:45 --- Created an attachment (id=20868) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20868&action=view) testcase.i -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44469
