Ensure that functions take four or fewer arguments if each argument is a word or less in size. In C++, ensure that nonstatic member functions take three or fewer arguments because of the implicit this pointer argument that is usually passed in R0.

Ensure that a function does a significant amount of work if it requires more than four arguments, so that the cost of passing the stacked arguments is outweighed.

Put related arguments in a structure, and pass a pointer to the structure in any function call. This reduces the number of parameters and increases readability.

Minimize the number of long long parameters, because these take two argument words that have to be aligned on an even register index.

Minimize the number of double parameters when using software floating-point.

Avoid functions with a variable number of parameters. Functions taking a variable number of arguments effectively pass all their arguments on the stack.