Solidity IR-based Codegen Changes

In mainline Ethereum Solidity, the compiler has transitioned from a direct stack-based lowering engine to an intermediate representation (Yul) based codegen pipeline.

Neo DevPack for Solidity Pipeline

💡 NeoVM Difference

Neo DevPack for Solidity uses its own custom Intermediate Representation (IR), which is specifically designed for the stack-based, non-linear architecture of the Neo Virtual Machine.

Because NeoVM relies heavily on high-level StackItem objects (Array, Map, ByteArray) rather than linear byte manipulation, standard Yul cannot be cleanly compiled to Neo.

Instead, Neo DevPack for Solidity's compilation pipeline works as follows:

1. Frontend: Parses standard Solidity 0.8.x syntax into an AST using solang-parser.
2. Semantic Analysis: Builds a fully resolved type graph and validates EVM constraints.
3. Neo IR Generation: Lowers the AST into Neo DevPack for Solidity IR, mapping EVM concepts (like mappings or struct memory) into Neo operations (like SHA256 key derivation or NEWARRAY).
4. Optimization: Performs dataflow analysis, constant folding, and dead code elimination on the Neo IR.
5. NeoVM Bytecode Generation: Emits final Neo N3 opcodes (JMP, CALL, SYSCALL, etc.).

This custom pipeline is why Neo DevPack for Solidity is able to bypass EVM's 256-bit packing limitations and offer seamless large-integer and array-based struct manipulations at runtime.