registers vs stacks

language-agnostic vm-implementation stack-based
Jason Baker picture Jason Baker · Oct 2, 2008 · Viewed 27.5k times · Source

What exactly are the advantages and disadvantages to using a register-based virtual machine versus using a stack-based virtual machine?

To me, it would seem as though a register based machine would be more straight-forward to program and more efficient. So why is it that the JVM, the CLR, and the Python VM are all stack-based?

Answer

Ferruccio picture Ferruccio · Oct 2, 2008

Implemented in hardware, a register-based machine is going to be more efficient simply because there are fewer accesses to the slower RAM. In software, however, even a register based architecture will most likely have the "registers" in RAM. A stack based machine is going to be just as efficient in that case.

In addition a stack-based VM is going to make it a lot easier to write compilers. You don't have to deal with register allocation strategies. You have, essentially, an unlimited number of registers to work with.

Update: I wrote this answer assuming an interpreted VM. It may not hold true for a JIT compiled VM. I ran across this paper which seems to indicate that a JIT compiled VM may be more efficient using a register architecture.

Related questions

What and where are the stack and heap?

Programming language books explain that value types are created on the stack, and reference types are created on the heap, without explaining what these two things are. I haven't read a clear explanation of this. I understand what a stack …

Read More
What is dependency injection?

There have been several questions already posted with specific questions about dependency injection, such as when to use it and what frameworks are there for it. However, What is dependency injection and when/why should or shouldn't it be used?

Read More
Regex to match only letters

How can I write a regex that matches only letters?

Read More