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