Code optimization techniques for micro-code compilers

With the ever expanding volume of system functions directly implemented in microcode and the growth of microprocessor applications, it has become necessary to design high level language compilers for these machines to achieve high programming productivity. However, because of the very low level architecture of many of these machines, compilers that generate efficient code for these machines have not been produced. An optimizing compiler, called PL/MP, has been designed which is capable of supporting a variety of microprocessors such as the Motorola M6800 as well as machines like the IBM 370 model 145, and several microprocessors designed and used internally at IBM.1 PL/MP uses a set of novel, machine dependent, and the more conventional high level, machine independent optimization techniques to achieve high object code quality. Experimental results have indicated that the machine dependent optimizations playa very significant role in enhancing the quality of the object code produced by the compiler. The most effective of these optimizations are