[Bug tree-optimization/39204] [4.4 Regression] ICE in compute_attic

[rguenth at gcc dot gnu dot org]

------- Comment #8 from rguenth at gcc dot gnu dot org  2009-02-17 13:11 -------
The change that the UID variations cause is ordering of two PHI-nodes which
result in

 Value numbers:
-line_37 = line_18
+line_18 = line_37

from

<bb 7>:
  # line_23 = PHI <line_37(9), 0B(6)>
  # line_32 = PHI <line_18(9), line_29(6)>

<bb 9>:
  # line_37 = PHI <line_23(17), line_14(19)>
  # line_18 = PHI <line_23(17), line_14(19)>

during compute_antic we endlessly set changed to true in

  /* !old->expressions can happen when we deferred a block.  */
  if (!old->expressions || !bitmap_set_equal (old, ANTIC_IN (block)))
    {
      changed = true;
      SET_BIT (changed_blocks, block->index);
      FOR_EACH_EDGE (e, ei, block->preds)
        SET_BIT (changed_blocks, e->src->index);

only.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dberlin at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39204