[Bug libstdc++/32907] New: Inefficent operator== in std::string and std::list

["chris at bubblescope dot net" <gcc-bugzilla at gcc dot gnu dot org>]

This is picked up from http://gcc.gnu.org/ml/gcc/2007-07/msg00681.html ,
apologises if it has already been dealt with.

Both std::string and std::list do not compare lengths before comparing elements
in operator==. In std::string this increases the chances of quitting early and
produces a small improvement even for equal length strings. For std::list this
produces a much larger gain. I believe the operator== for list should simply be
replaced implementation used for all the other containers:

{ return (__x.size() == __y.size()
              && std::equal(__x.begin(), __x.end(), __y.begin())); }

Which is efficent as list has a O(1) size.


-- 
           Summary: Inefficent operator== in std::string and std::list
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: chris at bubblescope dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32907