WASM 2.0

The specification of WebAssembly validation is purely declarative. It describes the constraints that must be met by a module or instruction sequence to be valid. This section sketches the skeleton of a sound and complete algorithm for effectively validating code, i.e., sequences of instructions. (Other aspects of validation are straightforward to implement.) In fact, the algorithm is expressed over the flat sequence of opcodes as occurring in the binary format, and performs only a single pass over it. Consequently, it can be integrated directly into a decoder. The algorithm is expressed in typed pseudo code whose semantics is intended to be self-explanatory. Data Structures Types are representable as an enumeration. type val_type = I32 | I64 | F32 | F64 | V128 | Funcref | Externref func is_num ( t : val_type | Unknown) : bool = return t = I32 || t = I64 || t = F32 || t = F64 || t = Unknown func is_vec ( t : val_type | Unknown) : bool = return t = V128 || t = Unknown func is_ref ( ... Read full article.