------- Additional Comments From belyshev at lubercy dot com 2004-11-25 11:16 ------- use this awk script to generate testcase (first arg is number of loops): ---------------------------------------------------------------------------------------- BEGIN { ORS="" print "int f ()\n{\tint " for (j = 0; j < ARGV [1]; j++) print "j" j ", " print "a;\n\ta = 0;\n" print "\tfor (j0 = 0; j0 < 2; j0 ++)\n" for (j = 1; j < ARGV [1]; j++) print "\tfor (j" j " = j" j-1 "; j" j " < 2; j" j" ++)\n" print "\ta += " for (j = 0; j < ARGV [1]-1; j++) print "j" j " + " print "j" j ";\n\treturn a;\n}\n" } ----------------------------------------------------------------------------------------
N loops Time, s 5 0.05 10 0.17 15 0.38 20 1.14 25 2.81 30 4.68 35 7.52 40 13.6 45 21.8 50 25.6 55 33.9 -- What |Removed |Added ---------------------------------------------------------------------------- Severity|minor |normal Status|UNCONFIRMED |NEW Ever Confirmed| |1 Keywords| |memory-hog Known to fail| |4.0.0 Last reconfirmed|0000-00-00 00:00:00 |2004-11-25 11:16:30 date| | Summary|IV-OPTS is slow (and does |[4.0 Regression] IV-OPTS is |not scale) |O(N^3) Target Milestone|--- |4.0.0 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18595