[Bug bootstrap/47044] New: bootstrap comparison failure when -O2 defaults on -fgraphite-identity

["howarth at nitro dot med.uc.edu" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47044

           Summary: bootstrap comparison failure when -O2 defaults on
                    -fgraphite-identity
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: howarth@nitro.med.uc.edu


On x86_64-apple-darwin10 at r168176 with...

Index: gcc/opts.c
===================================================================
--- gcc/opts.c    (revision 168176)
+++ gcc/opts.c    (working copy)
@@ -458,6 +458,9 @@
     { OPT_LEVELS_1_PLUS, OPT_fcombine_stack_adjustments, NULL, 1 },

     /* -O2 optimizations.  */
+#ifdef HAVE_cloog
+    { OPT_LEVELS_2_PLUS, OPT_fgraphite_identity, NULL, 1 },
+#endif
     { OPT_LEVELS_2_PLUS, OPT_finline_small_functions, NULL, 1 },
     { OPT_LEVELS_2_PLUS, OPT_findirect_inlining, NULL, 1 },
     { OPT_LEVELS_2_PLUS, OPT_fpartial_inlining, NULL, 1 },

applied to default on -fgraphite-identity at -O2, a bootstrap comparison
failure occurs...


Comparing stages 2 and 3
warning: gcc/cc1-checksum.o differs
warning: gcc/cc1obj-checksum.o differs
warning: gcc/cc1objplus-checksum.o differs
warning: gcc/cc1plus-checksum.o differs
Bootstrap comparison failure!
gcc/alias.o differs
gcc/attribs.o differs
gcc/bb-reorder.o differs
gcc/bitmap.o differs
gcc/bt-load.o differs
gcc/build/genattrtab.o differs
gcc/build/genautomata.o differs
gcc/build/genflags.o differs
gcc/build/gengenrtl.o differs
gcc/build/gengtype-lex.o differs
gcc/build/gengtype-state.o differs
...

This problem did not occur at r167670.
http://gcc.gnu.org/ml/gcc-testresults/2010-12/msg00852.html

../gcc-4.6-20101222/configure --prefix=/sw --prefix=/sw/lib/gcc4.6
--mandir=/sw/share/man --infodir=/sw/lib/gcc4.6/info
--enable-languages=c,c++,fortran,objc,obj-c++,java --with-gmp=/sw
--with-libiconv-prefix=/sw --with-ppl=/sw --with-cloog=/sw --with-mpc=/sw
--with-system-zlib --x-includes=/usr/X11R6/include --x-libraries=/usr/X11R6/lib
--program-suffix=-fsf-4.6 --enable-checking=yes --enable-cloog-backend=isl
--enable-build-with-cxx