[Bug middle-end/54146] Very slow compile at -O1 (expand vars)

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54146

--- Comment #3 from Steven Bosscher <steven at gcc dot gnu.org> 2012-07-31 
20:33:56 UTC ---
Time is spent in add_scope_conflicts() in this loop:

  FOR_EACH_BB (bb)
    add_scope_conflicts_1 (bb, work, true);