Message ID | 510FF01D.5040309@mentor.com |
---|---|
State | New |
Headers | show |
> The problem is that in delete_insn, while deleting an undeletable label (in > other words, transforming a label into a INSN_NOTE_DELETED_LABEL): > - we try to find the bb of a NOTE_INSN_BASIC_BLOCK following the label using > BLOCK_FOR_INSN (which is NULL) instead of NOTE_BASIC_BLOCK (which is not > NULL), and > - we don't handle the case that we find a NULL pointer for that bb > gracefully. Can the NOTE_BASIC_BLOCK of a NOTE_INSN_BASIC_BLOCK really be NULL? > This comment in insn-notes.def tells us that the bb info could be in either > of the two: > ... > /* Record the struct for the following basic block. Uses > NOTE_BASIC_BLOCK. FIXME: Redundant with the basic block pointer > now included in every insn. */ > INSN_NOTE (BASIC_BLOCK) > ... > > The patch fixes the problems by: > - using NOTE_BASIC_BLOCK to find the bb of NOTE_INSN_BASIC_BLOCK, and > - explicitly handling the cases that the bb of either the label or the note > is NULL. I don't think that we need to handle the very last case. > 2013-02-04 Tom de Vries <tom@codesourcery.com> > > PR rtl-optimization/56131 > * cfgrtl.c (delete_insn): Use NOTE_BASIC_BLOCK instead of BLOCK_FOR_INSN > to get the bb of a NOTE_INSN_BASIC_BLOCK. Handle the case that the bb > of the label is NULL. Add comment. OK on principle, but remove the handling of the NULL NOTE_BASIC_BLOCK and keep everything in a single condition.
Index: gcc/cfgrtl.c =================================================================== --- gcc/cfgrtl.c (revision 195240) +++ 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 = BLOCK_FOR_INSN (insn); + basic_block bb = NULL, label_bb = BLOCK_FOR_INSN (insn); rtx bb_note = NEXT_INSN (insn); really_delete = false; @@ -143,8 +143,16 @@ delete_insn (rtx insn) NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL; NOTE_DELETED_LABEL_NAME (insn) = name; - if (bb_note != NULL_RTX && NOTE_INSN_BASIC_BLOCK_P (bb_note) - && BLOCK_FOR_INSN (bb_note) == bb) + if (bb_note != NULL_RTX + && NOTE_INSN_BASIC_BLOCK_P (bb_note)) + bb = NOTE_BASIC_BLOCK (bb_note); + + /* 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. */ + if (bb != NULL + && (bb == label_bb + || label_bb == NULL)) { reorder_insns_nobb (insn, insn, bb_note); BB_HEAD (bb) = bb_note;