[Bug tree-optimization/17100] Missed opportunity for value range optimization

[nathan at gcc dot gnu dot org]

------- Additional Comments From nathan at gcc dot gnu dot org  2004-10-12 10:34 -------
I think this is an artifact of the design of the current value range
propagation.  That's not really range propagation by comparison result CSEing. 
The loop exit is i < 10, and the next comparison is i == 15.  We can propagate
the 'i < 10' result
and deduce that i == 15 must be false.  The later i == -5 can't be determined
from the result of i < 10.

I suspect this will be much easier to fix with a proper SSA VRP pass.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17100