[Bug optimization/14863] New: [3.4 regression] unit-at-a-time causes miscompilation

["rguenth at tat dot physik dot uni-tuebingen dot de" <gcc-bugzilla at gcc dot gnu dot org>]

The bctest3 POOMA testcase gets miscompiled by
g++ (GCC) 3.4.0 20040319 (prerelease)
and newer and was fine with
g++ (GCC) 3.4.0 20040302 (prerelease)
and before.

I'm using an unincluded testcase because of libstdc++ compilation issues of
older releases and because using the .ii causes older releases to fail, too.
So this may be a libstdc++ issue (or just bad luck interaction).

Using -O on the testcase makes it pass, using -O -funit-at-a-time makes it
segfault with the exact failure depending on argv[0] length.  Unit at a time may
be just triggering the failure of some optimization pass due to changed inlining
heuristics, but I wasn't able to find an optimization switch that triggers it.

Delta is currently minimizing the large testcase.

-- 
           Summary: [3.4 regression] unit-at-a-time causes miscompilation
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at tat dot physik dot uni-tuebingen dot de
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14863