You could do some tricks with GCC like not specifying arguments in your MOV instructions and let GCC use the optimal registers it calculates during compiling. P

You could do some tricks with GCC like not specifying arguments in your MOV instructions and let GCC use the optimal registers it calculates during compiling. Practical consequence was that instead of doing some default MOV AX, [something] then MOV BX, [something], then e.g. MUL BX, you could have avoided the first two operations as GCC would chain them together properly without the need to fill in values; so by inlining such code you'd get very very close to hand-written assembly language without additional overhead, speeding up your 3D engine significantly.