[Bug optimization/2692] excessive compile time with optimization

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2004-01-15 01:16 -------
Current state on mainline, at least for x86 at -O2, is that we spend lots
of time in flow doing dead store elimination,

 life analysis         :  60.94 (76%) usr   0.00 ( 0%) sys  61.02 (75%) wall
 TOTAL                 :  80.58             0.39            81.01

If I tweek flow.c to not do *any* store elimination at all, I can pull
the total down to ~75 seconds.  I don't see anything easy to do to even
bridge the gap between these two times at this late stage of 3.4.

On tree-ssa branch, we do significantly better.

 TOTAL                 :  18.08             0.51            18.57

This with the original C++ test case.  If I crop the std::dcomplex parts
and use the _Complex support in C, then I get

 TOTAL                 :   5.85             0.17             6.01

Clearly there's work to do yet in unraveling the abstraction, but either
compilation time is acceptable, so I'm going to suspend this PR as fixed
pending merge to mainline.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |SUSPENDED
   Target Milestone|---                         |tree-ssa


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=2692