Problems when compiling premap.c with -O1/-O2/-O3

[darealshinji]

Compiling Game/src/premap.c with -O1/-O2/-O3 enabled will cause the game to crash when I start a new game. I'm using gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) on Ubuntu 14.04 and the DN3D shareware version.