[Bug middle-end/17503] quadratic behaviour in invalid_mode_change_p

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2004-09-20 21:41 -------
"Huge"?  Ok, so the thing's now at the top of the profile, but it still only uses
four (4) seconds of cpu time, so fixing it isn't going to help *that* much.  I've
reduced the severity of the pr.

I suspect that you can only see this effect at -O0 with Truely Large synthetic
functions, as seen in insn-attrtab.c.  So I am caring only a little at the moment.

Note that the "regression" comes not from the stack slot sharing per-se, but 
actually honoring use_register_for_decl, which is true for scalar temporaries.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|critical                    |normal
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-09-20 21:41:01
               date|                            |
            Summary|[4.0 Regression] Huge       |quadratic behaviour in
                   |performance regression in   |invalid_mode_change_p
                   |invalid_mode_change_p       |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17503