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23667: Recent performance regression
- From: Paolo Carlini <pcarlini at suse dot de>
- To: gcc at gcc dot gnu dot org
- Cc: "Joseph S. Myers" <joseph at codesourcery dot com>
- Date: Fri, 02 Sep 2005 18:57:42 +0200
- Subject: 23667: Recent performance regression
Hi,
this is just an heads-up: PR libstdc++/23667 is about a time-out, on
slower machines of tr1/6_containers/unordered/hashtable/23465.cc.
However, If I use together with the library an up to date compiler
(either mainline or 4_0-branch), I'm able to appreciate the horrible
slow-down of the generated code (1-2 orders of magnitude!) also on
x86-linux. I believe a recent correct-ness fix introduced an unintented
pessimization.
In order to avoid seeing a spurious correctness regression in the logs
(the testcase is in the correctness library testsuite, not in the
performance one), I simplified the testcase, thus made it much faster,
but now I see that the underlying issue is generic and very serious: in,
say, 3-4 days, I will revert the change in case the slow-down will be
still present.
Thanks,
Paolo.