转自:http://blog.****.net/cws1214/article/details/12023093
when linux gdb debug, print a variable, such as i, by command p i;
The gdb output value optimized out.
The solution for the problem is off the compile optimation option -Ox, x note digital, such 2, 3, 4 etc
The better way is that changing -Ox to -O0.
The -O0 denotes there is no optimization. It will avoid gdb mislead source code line issue.