http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56131
--- Comment #14 from vries at gcc dot gnu.org 2013-02-22 10:30:06 UTC --- Steven, thanks for the comments. > Nothing even trying to look at the CFG after freeing it, so the looks at > BLOCK_FOR_INSN in delete_insn are non-sense. AFAIU now from http://gcc.gnu.org/onlinedocs/gccint/Maintaining-the-CFG.html#Maintaining-the-CFG, BLOCK_FOR_INSN == NULL shows whether the CFG has been freed or not, so I'd say it makes sense to test for equality of BLOCK_FOR_INSN when non-NULL. > Looking for the basic block > anywhere at all at this point makes no sense, If I understand you correctly with 'this point' you mean 'after the CFG has been freed'? > basic block contents and > boundaries are not maintained and may be scrambled enough to make even > the basic block notes unreliable. OK. I've added a comment in insn-notes.def in the patch below to make that more explicit. > Also, "If the label is not marked with a bb, assume it's the same bb" > is wrong if the label is a marker for a constant pool or a jump table. OK, fixed in patch below. Does this patch address all your concerns? ... Index: gcc/insn-notes.def =================================================================== --- gcc/insn-notes.def (revision 195874) +++ gcc/insn-notes.def (working copy) @@ -70,7 +70,9 @@ INSN_NOTE (CALL_ARG_LOCATION) /* Record the struct for the following basic block. Uses NOTE_BASIC_BLOCK. FIXME: Redundant with the basic block pointer - now included in every insn. */ + now included in every insn. NOTE: If there's no CFG anymore, in other words, + if BLOCK_FOR_INSN () == NULL, NOTE_BASIC_BLOCK cannot be considered reliable + anymore. */ INSN_NOTE (BASIC_BLOCK) /* Mark the inflection point in the instruction stream where we switch Index: gcc/cfgrtl.c =================================================================== --- gcc/cfgrtl.c (revision 195874) +++ gcc/cfgrtl.c (working copy) @@ -135,7 +135,7 @@ delete_insn (rtx insn) if (! can_delete_label_p (insn)) { const char *name = LABEL_NAME (insn); - basic_block bb, label_bb = BLOCK_FOR_INSN (insn); + basic_block bb = BLOCK_FOR_INSN (insn); rtx bb_note = NEXT_INSN (insn); really_delete = false; @@ -144,15 +144,13 @@ delete_insn (rtx insn) NOTE_DELETED_LABEL_NAME (insn) = name; /* If the note following the label starts a basic block, and the - label is a member of the same basic block, interchange the two. - If the label is not marked with a bb, assume it's the same bb. */ + label is a member of the same basic block, interchange the two. */ if (bb_note != NULL_RTX && NOTE_INSN_BASIC_BLOCK_P (bb_note) - && (label_bb == NOTE_BASIC_BLOCK (bb_note) - || label_bb == NULL)) + && bb != NULL + && bb == BLOCK_FOR_INSN (bb_note)) { reorder_insns_nobb (insn, insn, bb_note); - bb = NOTE_BASIC_BLOCK (bb_note); BB_HEAD (bb) = bb_note; if (BB_END (bb) == bb_note) BB_END (bb) = insn; ...
