[Bug bootstrap/54128] New: GCC does not bootstrap on little endian mips due to mis-compare on tree-data-ref.c

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54128

             Bug #: 54128
           Summary: GCC does not bootstrap on little endian mips due to
                    mis-compare on tree-data-ref.c
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: sje@gcc.gnu.org


A bootstrap using the latest GCC fails on a little endian MIPS system due to a
compare failure.

make[3]: Leaving directory `/home2/sje/gcc_native/obj-native/gcc'
Comparing stages 2 and 3
warning: gcc/cc1plus-checksum.o differs
warning: gcc/cc1-checksum.o differs
Bootstrap comparison failure!
gcc/tree-data-ref.o differs
make[2]: *** [compare] Error 1

It looks like someone else saw this on a debian box and submitted a debian
bug, http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=634881, but their fix
was to workaround it by using -gtoggle for both the stage 2 and stage 3 builds.
It is -gtoggle that is causing the difference.  Comparing the two objects I see
a small code gen difference in  "analyze_subscript_affine".  I have attached
the preprocessed version of that source file to this bug report.  Compiling it
with C++ and "-g -O2 -fno-exceptions -fno-rtti -fno-common" in one case and
adding -gtoggle in the second case should show the codegen difference.  You may
need -EL if using a mips GCC that does not generated little-endian by default.