[Bug rtl-optimization/19097] [3.4/4.0/4.1/4.2 regression] Quadratic behavior with many sets for the same register in gcse CPROP

[steven at gcc dot gnu dot org]

------- Comment #30 from steven at gcc dot gnu dot org  2006-01-08 16:08 -------
Other than VRP taking so much time for GCC 4.1, there are no surprises in the
timings I just added in comment #29 for GCC 4.0 and GCC 4.1.

Computing dominance frontiers is just not a linear operation (especially not
for a function with this many of them :-).  "CPROP 1", "CPROP 2", and "bypass
jumps" are all the same algorithm (const/copy propagation in gcse.c) which also
has known non-linear algorithms for strange test cases like the one for this
bug report.

If only VRP wouldn't suck up so much time here, I would call this one FIXED...


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19097