Eric,
This patch fixes PR56131.
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.
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.
Bootstrapped and reg-tested by Mikael Pettersson on both x86_64-linux and
sparc64-linux.
OK for trunk?
Thanks,
- Tom
2013-02-04 Tom de Vries <t...@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.
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;
