Platform reference#

The virtual machine described as a specification, not as a program. Which instructions exist, what each one does, how arguments are passed and how the file it executes is laid out.

• Instruction set
• Registers
• Calling convention
• The .velb format
• The .vela archive
• VM syscalls

Why this is not in Compiler Internals#

The virtual machine might look like the internal detail par excellence. But the split in this documentation is not by topic, it is by the kind of claim, and these pages are normative: they describe a contract any implementation would have to honour.

The difference shows best with an example. That an instruction takes its operands in a given order is part of the contract, and a file compiled years ago has to keep running. Whether the interpreter dispatches those instructions with a jump table or a switch is invisible from outside, and so it lives in Compiler Internals.

If somebody ever writes another implementation of VestaVM, this section is what they would write it against.