[Bug libstdc++/58440] New: There seems to be a major performance regression in std::sort performance

[jmbnyc at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58440

            Bug ID: 58440
           Summary: There seems to be a major performance regression in
                    std::sort performance
           Product: gcc
           Version: 4.6.2
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jmbnyc at gmail dot com

Created attachment 30828
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30828&action=edit
cpp file the illustrates bug

The attached simple program illustrates a major performance degradation. I
first noticed this in gcc 4.7.2. I tried to figure out if the was the compiler
or the std library and was able to get 2 systems with same CPU but different
gcc versions to illustrate the problem also exists in 4.6. It might exist in
4.5 but I could not test that combination.

Here are my results:

Intel(R) Xeon(R) CPU           X5680  @ 3.33GHz

GCC 4.4.3
-bash-3.2$ g++ -O3 bug.cpp -o sort
-bash-3.2$ ./sort
elapsed: 12.970126

GCC 4.6.2
-bash-3.2$ g++ -O3 bug.cpp -o sort
-bash-3.2$ ./sort
elapsed: 77.040297