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[Bug tree-optimization/19701] [4.0 regression] Way too many IVs
- From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 30 Jan 2005 01:55:56 -0000
- Subject: [Bug tree-optimization/19701] [4.0 regression] Way too many IVs
- References: <20050130004850.19701.falk@debian.org>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-01-30 01:55 -------
(In reply to comment #4)
> Also happens on x86-64, but not on x86.
Well the IV selection on x86 is not good either.
*(long long unsigned int *) d.18 = 0;
D.1187 = (long long unsigned int *) ivtmp.4 + (long long unsigned int *) d;
*(D.1187 + 8B) = 0;
...
ivtmp.4 = ivtmp.4 + 64B;
if ((int) ((unsigned int) w - (unsigned int) ivtmp.4) > 63) goto <L10>; else goto <L2>;
Notice how we use ivtmp.4 for "d+8". And then we do w - ivtmp.4 when ivtmp.4 should go from w and
go down like what it is in the source. So we select the same IVs as in the source.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19701