#version 450
layout(location =0 ) in int c;
layout(location =0 ) out int o;
void main() {
int i = 0;
o = 1;
do {
o = 2;
return;
o = 3;
} while(i++ < 5);
// All this is a dead merge block.
o = 4;
if (c==4) {
o = 100;
} else {
o = 200;
}
o = 300;