Editing Stack machine (section)

=== Temporary / local values ===
Some in the industry believe that stack machines execute more [[data cache]] cycles for temporary values and local variables than do register machines.<ref name="Hennessy-Patterson"/>

On stack machines, temporary values often get spilled into memory, whereas on machines with many registers these temps usually remain in registers. (However, these values often need to be spilled into "activation frames" at the end of a procedure's definition, basic block, or at the very least, into a memory buffer during interrupt processing). Values spilled to memory add more cache cycles. This spilling effect depends on the number of hidden registers used to buffer top-of-stack values, upon the frequency of nested procedure calls, and upon host computer interrupt processing rates.

On register machines using optimizing compilers, it is very common for the most-used local variables to remain in registers rather than in stack frame memory cells. This eliminates most data cache cycles for reading and writing those values. The development of "stack scheduling" for performing [[live-variable analysis]], and thus retaining key variables on the stack for extended periods, helps this concern.<ref name="Koopman_1994" /><ref name="Bailey_2000" /><ref name="Shannon-Bailey_2006" />

On the other hand, register machines must spill many of their registers to memory across nested procedure calls. The decision of which registers to spill, and when, is made statically at compile time rather than on the dynamic depth of the calls. This can lead to more data cache traffic than in an advanced stack machine implementation.