[Bug bootstrap/56927] 4.7.2 build ICEs when built with 4.8.0 and --disable-bootstrap

[segher at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56927

--- Comment #1 from Segher Boessenkool <segher at gcc dot gnu.org> 2013-04-11 19:25:05 UTC ---
Forgot to mention...  I debugged this a little; it happens during
the build of the 32-bit libgcc, and gdb says

Program received signal SIGSEGV, Segmentation fault.
build_conflict_bit_table ()
    at /home/segher/src/gcc-4.7.2/gcc/ira-conflicts.c:178
178                   ira_allocno_t live_a = OBJECT_ALLOCNO (live_obj);
(gdb) bt
#0  build_conflict_bit_table ()
    at /home/segher/src/gcc-4.7.2/gcc/ira-conflicts.c:178
#1  ira_build_conflicts ()
    at /home/segher/src/gcc-4.7.2/gcc/ira-conflicts.c:856
#2  0x000000000067eccf in ira_build ()
    at /home/segher/src/gcc-4.7.2/gcc/ira-build.c:3101
#3  0x0000000000679177 in ira (f=<optimized out>)
    at /home/segher/src/gcc-4.7.2/gcc/ira.c:3626
#4  rest_of_handle_ira () at /home/segher/src/gcc-4.7.2/gcc/ira.c:3798
[...]

(gdb) p live_obj
$1 = (ira_object_t) 0x0