[Bug tree-optimization/26830] [4.1/4.2 Regression] Insane amount of compile-time / memory needed at -O1 and above

[rguenth at gcc dot gnu dot org]

------- Comment #8 from rguenth at gcc dot gnu dot org  2006-03-23 22:09 -------
With structure aliasing on, we create 22326 SFTs for the
CShadingContext::execute function.  Aliasing completely breaks down then:

execute: Total number of aliased vops: 18901314
execute: Total number of aliased vops after grouping: 4421064

Referenced variables in execute: 80934

This all results in lots of basic blocks with hundreds of PHI nodes with
hundreds of incoming edges in alias1.  This is insane!  Like

  # SFT.14821_22241 = PHI <SFT.14821_41418(2), ... , SFT.14821_22241(9627)>;
(that line is 20000 characters long!  Which makes roughly 1000 phi arguments!)

and there are 8800 such PHI_EXPRs for just one basic block!


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26830