Alex Beregszaszi

Non-determinism with division by zero

13

Source: https://webassembly.github.io/spec/core/_download/WebAssembly.pdf pp48: idiv_u𝑁 (𝑖1, 𝑖2) • If 𝑖2 is 0, then the result is undefined. idiv_s𝑁 (𝑖1, 𝑖2) • If 𝑗2 is 0, then the result is undefined. •...

Propose an ewasm subset for precompiles on the main chain

4

The only features ewasm would need to expose are: - `useGas` - calldata access (`calldatacopy`/`calldatasize`) - `return` / `revert` This could be a way to get wasm VMs implemented and...

Ensure that memory expansion (grow_memory) aborts on failure

5

While the [metering "spec"](https://github.com/ewasm/design/blob/master/metering.md#increasing-memory) calls for prepending `grow_memory` with a gas check, the `grow_memory` opcode can still return a failure when enough gas is present, but not enough memory is...

[Primea](https://github.com/primea) has introduced a generic buffer API where each buffer is referred to by an index and helpers exists to query the size and retrieve the buffer. We could consider...

Atomic metering

9

This is a discussion we had with @wanderer at Devcon3. This is an attempt to determine upper bounds in metering. In short the proposal is that functions can be annotated...

Supporting smaller memory pages

23

This came up as a discussion at Devcon 4. I think the problem was mentioned by @poemm. Wasm has a fixed memory page size of 64kb of which a single...

See also https://github.com/ewasm/design/tree/move for a solution.

Ref: https://github.com/WebAssembly/design/blob/master/Nondeterminism.md Should clearly explain how do we handle these cases. In short: Out of that list only two things affect ewasm: - NaN on arithmetic operations. This only affects...

Strict argument handling of log()

8

`log` has a `numberOfTopics` argument and four topic offsets. Depending on the value of `numberOfTopics` (0 to 4) the offsets are used or not. Should the interface ensure that any...

Review if the reason for disallowing the start function still exists

3

Disallowing the [start function](https://github.com/ewasm/design/blob/master/contract_interface.md#start-function) and using a `main` function was decided based on a limitation in the Wasm Javascript API. I think it is time to review this limitation and...