webasm.md 1.4KB
Summarise Contribution & Motivation
- Web is becoming mature and now requires more complex applications to run on it
- Javascript is currently only built in language
- Javascript is not well equipped to deal with these applications or be a compile target
- WebAssembly is a low level bytecode for the web
- Aims to provide safe, low overhead execution
- Better solution than plugins for safety
- Better than asm.js for consistent performance
Methodology
- Defines modules for each binary and therefore allows imports
- Defines functions, not first class and not nested, call stack not exposed
- Instructions based in a stack machine, for compactness
- Only defines 4 types, integers and IEEE floating points
- Has global and local variables
- Memories defined by modules with little endianness, disjoint from code space and stack so programs can only mess up their own environment
- Does not offer simple jumps, has structured control flow, gives single pass validation/compilation/SSA
- Can do JIT and validation in single pass
- Transmitted over wire in binary form, streaming compilation possible due to layout
Critical Assessment
- Improves on native client by being available on all browsers as it is not compact and still requires knowledge of underlying system
- Traps are not handled but need JS intervention
- Still missing features for higher level languages
- A compile target for the web with safety by design should prevent many exploits -