ICE at -O1 and -02. Target specific error message at -O0. But even that would be more helpful if it told what the actual limit was.
$ avr-rtems4.10-gcc -mmcu=avr25 -O2 j.c -c ../../../../../rtems/cpukit/telnetd/des.c: In function 'des_init': ../../../../../rtems/cpukit/telnetd/des.c:274: internal compiler error: in tree_low_cst, at tree.c:4976 Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. $ avr-rtems4.10-gcc -mmcu=avr25 -O0 j.c -c ../../../../../rtems/cpukit/telnetd/des.c:87: error: size of variable 'des_f' is too large -- Summary: ICE in tree_low_cst, at tree.c:4976 Product: gcc Version: 4.3.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: joel at gcc dot gnu dot org GCC target triplet: avr-rtems4.10 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39184