[Bug tree-optimization/18595] [4.0 Regression] IV-OPTS is O(N^3)

[belyshev at depni dot sinp dot msu dot ru]

------- Additional Comments From belyshev at depni dot sinp dot msu dot ru  2004-12-22 23:40 -------
It seems that extra O(N) factor comes from high memory usage. For smaller N
(0..30) compiler behaves like O(2) and for larger (> 50) like O(2.5 .. 3).

gnuplot> fit [0:30] A*x**k+B "data" via A,k,B
[snip]
Final set of parameters            Asymptotic Standard Error
=======================            ==========================

A               = 0.000465461      +/- 2.625e-05    (5.64%)
k               = 1.90612          +/- 0.01652      (0.8667%)
B               = 0.0328722        +/- 0.0007677    (2.335%)

gnuplot> fit [50:175] A*x**k+B "data" via A,k,B
[snip]
Final set of parameters            Asymptotic Standard Error
=======================            ==========================

A               = 4.76329e-06      +/- 3.493e-07    (7.332%)
k               = 3.0033           +/- 0.01405      (0.4678%)
B               = 0.392746         +/- 0.02972      (7.567%)

For N=175 memory usage on my machine exceedes 600 MB

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2004-11-25 11:16:30         |2004-12-22 23:40:41
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18595