[Bug tree-optimization/18595] New: IV-OPTS is slow (and does not scale)

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

Using the program in PR 10060, to generate 1000 and 2000, I see that "IV OPT" goes from:
 tree iv optimization  :   1.79 (14%) usr   0.15 ( 5%) sys   2.60 (13%) wall
to
 tree iv optimization  :   6.92 (13%) usr   0.29 ( 5%) sys   7.30 (12%) wall

which looks like PHI iv opt does not scale O(n).

This is not as importran as PR 18594 though (which is the same testcase).

-- 
           Summary: IV-OPTS is slow (and does not scale)
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: minor
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18595