Java's Virtual Machine and CLR

submited by

Style Pass

2024-05-09 02:30:16

Communities for your favorite technologies. Explore all Collectives

Ask questions, find answers and collaborate at work with Stack Overflow for Teams. Explore Teams

As a sort of follow up to the question called Differences between MSIL and Java bytecode?, what is the (major) differences or similarity in how the Java Virtual Machine works versus how the .NET Framework Common Language Runtime (CLR) works?

For one thing, they're both stack-based VM's, with no notion of "registers" like we're used to seeing in a modern CPU like the x86 or PowerPC. The evaluation of all expressions ((1 + 1) / 2) is performed by pushing operands onto the "stack" and then popping those operands off the stack whenever an instruction (add, divide, etc) needs to consume those operands. Each instruction pushes its results back onto the stack.

It's a convenient way to implement a virtual machine, because pretty much every CPU in the world has a stack, but the number of registers is often different (and some registers are special-purpose, and each instruction expects its operands in different registers, etc).