Changes

* '''smaller''': less memory usage may be important for embedded computers used within other devices.

* '''smaller''': less memory usage may be important for embedded computers used within other devices.

* '''low power''': less power consumption may be important for battery-powered computers (e.g. laptops).

* '''low power''': less power consumption may be important for battery-powered computers (e.g. laptops).

Note that it is often only possible to optimise for a single criterion, since such optimisation may well make other criteria worse; it has been accepted for decades that many programs have a space/time trade-off so that reducing space will increase time and vice versa.

Note that it is often only possible to optimise for a single criterion, since such optimisation may well make other criteria worse; it has been accepted for decades that many programs have a space/time trade-off so that reducing memory usage will increase execution time and vice versa.

 

The bulk of the machine-independent optimisation takes place after the intermediate code is generated, effectively by re-arranging and modifying this code. Some machine-dependent optimisation may take place during register allocation. The bulk of the machine-dependent optimisation takes place during the generation of assembly language; this often includes extensive peep-hole optimisation to replace a group of assembler instructions by some shorter or simpler group.

==References==

==References==