[Bug target/47440] New: Use LCM for vzeroupper optimization

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47440

           Summary: Use LCM for vzeroupper optimization
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hjl.tools@gmail.com


From:

http://gcc.gnu.org/ml/gcc-patches/2010-12/msg01923.html
http://gcc.gnu.org/ml/gcc-patches/2011-01/msg00967.html

LCM infrastructure (see lcm.c) is suggested for placing vzerouppers at
optimum points.  Targeting 4.7.