The static single assignment form (SSA form) is becoming popular as an intermediate representation in compilers.
In the SSA form, the definition of each variable textually appears only once in the program by using a hypothetical function called a $?phi$-function.
Because these functions are nonexecutable, it is necessary to delete the
$?phi$-function and return the SSA form to the normal form before code generation.  This conversion is called SSA back-translation.
Two major algorithms exist for SSA back-translation.  One is the method by Briggs et al., the other is the method by Sreedhar et al.
To date, there has been almost no research that compares these SSA back- translation algorithms.
In this paper, we clarify the merits and demerits of these algorithms.
We also propose an improvement of Briggs' algorithm.
We then compare the three methods through experiments using the SPEC benchmarks.
Our experiments have shown that Sreedhar's method is the most favorable.
The efficiency of its object code is better than that from Briggs's method, by a few percent in general, up to a maximum of 28%.
The experiments have also clarified several characteristic features of these methods.