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[Bug fortran/19925] Implied do-loop in an initialization expression is broken
- From: "dominiq at lps dot ens dot fr" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 1 Feb 2008 15:31:49 -0000
- Subject: [Bug fortran/19925] Implied do-loop in an initialization expression is broken
- References: <bug-19925-8446@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #20 from dominiq at lps dot ens dot fr 2008-02-01 15:31 -------
With the patch in comment #18, on a Core2Duo 2.16Ghz I get:
5000 0.54 secs
10000 1.82
20000 6.74
40000 36.5
60000 206
65535 258
65536 68 <-- Error: Initialization expression didn't reduce (1)
80000 149 Ditto
100000 281 Ditto
So the threshold seems to be 2**16. While the timings in comment #18 seem more
or less cubic in n, on the Core2duo, they start more or less quadratic in n up
to 20000, then grow up much faster with n, as if they were the addition of one
quadratic behavior and one cubic (or faster) with prefactors depending on the
processor.
Note that the patch in #18, is not needed below some value of n: n=10000 pass
on unpatched ppc.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19925