[Bug bootstrap/59951] New: bootstrap comparison failure with -O3 for a week

[dcb314 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59951

            Bug ID: 59951
           Summary: bootstrap comparison failure with -O3 for a week
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com

With revision 207121, dated today 20140126, I tried a bootstrap
build with BOOT_CFLAGS="-g -O3". 

It went wrong in the following way

Comparing stages 2 and 3
warning: gcc/cc1-checksum.o differs
warning: gcc/cc1plus-checksum.o differs
Bootstrap comparison failure!
gcc/bitmap.o differs
gcc/fortran/decl.o differs
gcc/bt-load.o differs
libiberty/pic/md5.o differs
libiberty/md5.o differs
make[2]: *** [compare] Error 1
make[2]: Leaving directory `/home/dcb/gcc/working'
make[1]: *** [stage3-bubble] Error 2
make[1]: Leaving directory `/home/dcb/gcc/working'
make: *** [bootstrap] Error 2

real    75m53.471s
user    142m19.580s
sys    6m42.084s
Sun 26 Jan 21:02:51 GMT 2014

configure line is

../src/trunk/configure --prefix=/home/dcb/gcc/results --enable-checking=yes 
        --enable-languages=c,c++,fortran --disable-werror

Machine type is x86_64.

This also went wrong last Wednesday, 20140122 and last Sunday 20140119