I'm hoping someone brings WASM to MCUs with a HAL interface like WASI does for OS platform functionality. As far as I can tell, the byte code is simple and easy to write an interpreter for, with a lot of practically useful features like static memory blocks declared ahead of time that make it conducive to MCUs. It should even be possible to write test harnesses with simulators for each architecture that gives a precise prediction for how many cycles a given block of WASM will take in an interpreter so that timing for interrupt handlers, tasks, etc can all be worked out in simulation without even touching the hardware.
If a given block of WASM isn't performant enough in the interpreter, then drop it to compiled code and expose it to the rest of the WASM - at least then only a small fraction of your code requires a painful firmware upgrade, the rest can be updated in a user defined section of ROM. It would be great to have a compiler/linker combo that could use annotations to configure which parts of the firmware should be compiled and which should be interpreted. With inlining or even just AST substitution (replace global vars with register access), it should provide all of the low level access necessary while still allowing for high level Arduiono style libraries
If a given block of WASM isn't performant enough in the interpreter, then drop it to compiled code and expose it to the rest of the WASM - at least then only a small fraction of your code requires a painful firmware upgrade, the rest can be updated in a user defined section of ROM. It would be great to have a compiler/linker combo that could use annotations to configure which parts of the firmware should be compiled and which should be interpreted. With inlining or even just AST substitution (replace global vars with register access), it should provide all of the low level access necessary while still allowing for high level Arduiono style libraries