Loop quasi-invariance code motion

Loop optimization plays an important role in compiler optimization and prog ram transformation. Many sophisticated techniques such as loop-invariance c ode motion, loop restructuring and loop fusion have been developed. This pa per introduces a novel technique called loop quasi-invariance code motion. It is a generalization of standard loop-invariance code motion, but based o n loop quasi-invariance analysis. Loop quasi-invariance is similar iu stand ard loop-invariance but allows for a finite number of iterations before com putations in a loop become invariant. In this paper we define the notion of loop quasi-invariance, present an algorithm for statically computing the o ptimal unfolding length in While-programs and give a transformation method. Our method carl increase the accuracy of program analyses and improve the efficiency of programs by making loops smaller and faster. Our technique is well-suited as supporting transformation in compilers, partial evaluators, and other program transformers.