[Bug rtl-optimization/15566] Cross-compile ppc64 compile never finishes

["giovannibajo at libero dot it" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From giovannibajo at libero dot it  2004-05-23 03:23 -------
Confirmed by TM.

The problem appears to be in CSE (log is slightly edited for readability):

[04:43] <tm3> it keeps calling delete_reg_equiv(regno = 122)
[04:43] <tm3> delete_reg_equiv thinks the equivalence is invalid, so it punts 
and just returns
[04:43] <tm3> and it keeps getting called over and over again
[04:44] <pinskia> Law added flush_hash_table in http://gcc.gnu.org/ml/gcc-
patches/1999-04n/msg00240.html
[04:53] <tm3> yah, it looks like flush_hash_table is trying to clear the 
equivalences for reg 22? and going into an infinite loop
[04:54] <tm3> no...hash entry 22
[04:59] <DannyB> the algorithm for memory equivalances is O(n^2)
[05:00] <DannyB> so it just flushes every x insns to keep it fast
[05:02] <DannyB> " /* If we have processed 1,000 insns, flush the hash table to
[05:02] <DannyB>    avoid extreme quadratic behavior."

So, it looks like the underlying algorithm should be fixed instead.

TM: can you please provide the preprocessed testcase that shows this bug? Also, 
which branch did you bootstrap to confirm this?


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |giovannibajo at libero dot
                   |                            |it, tm_gccmail at kloo dot
                   |                            |net, law at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|c                           |rtl-optimization
     Ever Confirmed|                            |1
           Keywords|                            |compile-time-hog
      Known to fail|                            |3.4.0
   Last reconfirmed|0000-00-00 00:00:00         |2004-05-23 03:23:10
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15566