[Bug rtl-optimization/43360] [4.3/4.4/4.5 Regression] possible wrong code bug

["ebotcazou at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #7 from ebotcazou at gcc dot gnu dot org  2010-03-14 21:40 -------
> So, the solution is to teach loop2_invariant to also look into REG_EQUAL notes
> if the insn is _really_ invariant or eventually clear REG_EQUAL notes when
> insn is moved out of the loop.

Both should already happen though, see move_invariant_reg:

      /* If there is a REG_EQUAL note on the insn we just moved, and
         insn is in a basic block that is not always executed, the note
         may no longer be valid after we move the insn.
         Note that uses in REG_EQUAL notes are taken into account in
         the computation of invariants.  Hence it is safe to retain the
         note even if the note contains register references.  */
      if (! inv->always_executed
          && (note = find_reg_note (inv->insn, REG_EQUAL, NULL_RTX)))
        remove_note (inv->insn, note);

so there is apparently a flaw somewhere.


-- 

ebotcazou at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43360