[Bug rtl-optimization/52000] New: cross-jumping drops MEM attributes even when it makes no changes to the code

["rsandifo at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52000

             Bug #: 52000
           Summary: cross-jumping drops MEM attributes even when it makes
                    no changes to the code
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: rsandifo@gcc.gnu.org


flow_find_cross_jump calls merge_memattrs for each pair of
instructions that it was thinking of merging, regardless of
whether the merge takes place.  This can cause mem attributes
to be dropped unnecessarily.  See:

    http://gcc.gnu.org/ml/gcc/2012-01/msg00015.html

for more discussion and context.