Goal

It is possible to instrument Wasm kernels to avoid kernels accidentally deviating from PVM semantics.

Breakdown

• Gas budget per checkpoint check
• Stack depth checks
• No or Predictable Floating-point check
• Observing consumed gas (e.g. through Host Function available in instrumented mode only)
• Handle non O(1) instructions - Memory - Copy - Set - Table - Copy - Set - Others

Strategy

• Not part of PVM - no need to tickify
• Add unsafe host functions to ref interpreter (for testing infra) - Write function : instr -> instr - Group O(1) instructions (eliminates some branch points but maybe not all)

Design document

https://www.notion.so/trilitech/WASM-Rollup-0d2a996db2d8484fb87615bf5a96914d