[Bug tree-optimization/54146] Very slow compile with attribute((flatten))

[steven at gcc dot gnu.org]

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

--- Comment #21 from Steven Bosscher <steven at gcc dot gnu.org> 2012-08-06 
15:36:04 UTC ---
(In reply to comment #20)

Yay, it's always nice to be right the first time when diagnosing a problem.

The tree loop optimizers spend 285s out of 1360s total compile time (with my
flatten hack and ifcvt patch applied) in compute_global_livein. That's 21% of
the total compile time.

I have a few ideas for how to fix this.