$ cat >hoge.c
int main()
{
        int LOVE=0;
        while(1){LOVE++;}
}
$ gcc -O0 -S hoge.c; cp hoge.s hoge.s0 ; gcc -O1 -S hoge.c ; diff -c hoge.s{0,}
*** hoge.s0     2011-06-16 05:21:00.188942015 +0900
--- hoge.s      2011-06-16 05:21:00.204941785 +0900
***************
*** 5,14 ****
  main:
        pushl   %ebp
        movl    %esp, %ebp
-       subl    $16, %esp
-       movl    $0, -4(%ebp)
  .L2:
-       addl    $1, -4(%ebp)
        jmp     .L2
        .size   main, .-main
        .ident  "GCC: (Ubuntu/Linaro 4.5.2-8ubuntu4) 4.5.2"
--- 5,11 ----

MCE 0
HARDWARE ERROR. This is *NOT* a software problem!
Please contact your hardware vendor
CPU 1 BANK 8 TSC 25fa59bc557218 [at 2926 Mhz 42 days 6:48:3 uptime (unreliable)]
MISC 8e02082000000186 ADDR 1082baf00
MCG status:
MCi status:
Error overflow
MCi_MISC register valid
MCi_ADDR register valid
MCA: MEMORY CONTROLLER RD_CHANNELunspecified_ERR
Transaction: Memory read error
STATUS cc0001800001009f MCGSTATUS 0