[js-api] Monitoring the execution of Wasm

Functions defined in embedding section provide abstraction of Wasm's mechanics to embedders. However, I found a case in JS API specification that breaks this abstraction: monitoring the execution of Wasm. I'm curious whether these are inevitable or intentional.

Abstraction over the mechanics of Wasm execution is achieved by the embedding function func_invoke. As shown in Fig. 1, it takes a function address, invokes the corresponding function, and returns the result. By using this function, the embedder does not need to understand how execution of Wasm is performed.

Fig. 1: Embedding function func_invoke

However, there is an algorithm that must run immediately after a WebAssembly memory.grow instruction executes, which requires monitoring the Wasm execution context. Not only that, this algorithm inspects the value at the top of the stack (line 1) and accesses the current frame (line 1.1-1.3). These steps even require knowledge of the composition of the Wasm state and direct access to its internal structures.

These requirements significantly breaks the abstraction layer established by func_invoke. Could the algorithm be reformulated in a way that preserves this abstraction?

Fig.2: JS API algorithm which is performed "immediately after a WebAssembly memory.grow instruction executes"

Start with the embedding section's func_invoke definition and the JS API algorithm that runs after memory.grow, following the linked specification steps and the two figures. Determine whether the algorithm can preserve the embedding abstraction, and document a resolved specification direction or reformulation.