[Bug fortran/50875] New: O3 and -march=native lead to internal compiler error: in find_reloads

["holyjoly at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50875

             Bug #: 50875
           Summary: O3 and -march=native lead to internal compiler error:
                    in find_reloads
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: holyjoly@gmail.com


Created attachment 25618
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25618
Stripped down test case.

It appears that for certain combinations of array allocations, conditionals and
loops, gfortran 4.6 and 4.7 give :
"internal compiler error: in find_reloads, at reload.c:4067",
but only when paired with -O3 and -march=native.

Tried compiling against 4.6.1 and 4.7.0 20111010 (experimental) [trunk revision
179769]. It works against 4.4.6 and 4.5.4.

I tried on two Sandy-Bridge systems, an i7 with Scientific Linux and an i5 with
Ubuntu 11.10 and Mac OS X (Only tried 4.6 on this platform), which all gave the
same behaviour.

I have attached a completely stripped down test case (doesn't do anything
meaningful) which works against 4.5 and 4.4 but not later versions for the
described flags. The output of this when compiled against the earlier versions
is:
 (-6.6689347635125245, -3.4315183934768561)
(-0.21071909368227187,-0.21353560926074711)
 (-2.3118973846843422, -1.1895930430719770)
(-3.7929436862808936,-3.8436409666934486).
NB. spaces stripped out.

For the moment, I am working around this by compiling the offending module with
-O2, which works.

Hope this helps, if you need any more information, please ask.

Regards,
Joly.