https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108657
--- Comment #13 from David Binderman <dcb314 at hotmail dot com> --- I tried adding flag 1 to the run of the two binaries. Here is the bash history: 1003 gcc bug880.c 1004 ./a.out > /tmp/0 1005 ~/gcc/results/bin/gcc -w -O3 -ftrivial-auto-var-init=zero bug880.c -o b.out 1006 ./b.out > /tmp/1 1007 diff /tmp/0 /tmp/1 1008 ./a.out 1 > /tmp/0 1009 ./b.out 1 > /tmp/1 1010 diff /tmp/0 /tmp/1 and got this: 4,12c4,12 < ...checksum after hashing g_78 : 42AE7A83 < ...checksum after hashing g_86 : EA4E5BB < ...checksum after hashing g_87 : 829B71B1 < ...checksum after hashing g_93 : 454CD723 < ...checksum after hashing g_105 : 589C9AA7 < ...checksum after hashing g_111 : D1C885DD < ...checksum after hashing g_132 : A790B35F < ...checksum after hashing g_133 : A9573918 < ...checksum after hashing g_134[i] : 9B3BD0DE --- > ...checksum after hashing g_78 : 8E047A1D > ...checksum after hashing g_86 : A0CC742A > ...checksum after hashing g_87 : 3BE1496 > ...checksum after hashing g_93 : B496D289 > ...checksum after hashing g_105 : F7D808E0 > ...checksum after hashing g_111 : EC796901 > ...checksum after hashing g_132 : BA05A088 > ...checksum after hashing g_133 : 2662148D > ...checksum after hashing g_134[i] : 3530834A So someplace in g_78 looks to be the culprit.