A stack-based virtual machine for executing smart contracts, created using Axia's vmgen.
FireVM provides a strict superset of the functionality offered by Ethereum's EVM. This means that all contracts which can be executed on the Ethereum blockchain can be executed on any chain using FireVM (although a translation mechanism is necessary).
FireVM employs several strategies designed to minimise the size of the bytecode which must be stored on-chain.
EVM parameters are padded to 32 bytes, such that a boolean is stored as 0x0000000000000001 or 0x0000000000000000. This is unnecessarily wasteful.
FireVM stores the size of each parameter as a prefix, such that the representation of the boolean above is 0x0101 - one size byte and then one value byte. This assumes a size byte of length 1, but the size byte can modified by altering the first byte of the contract:
01 | size of size byte 01 | size of parameter 01 | actual parameter
While this does introduce some overhead, it is limited to one byte, with this constant addition being quickly overwhelmed as the contract grows larger.
This means that for a size parameter of length n, we have the following formula to calculate the reduction :
reduction := 32 - lengthInBytes - nSee SPEC.md for full details.