Welcome to better optimised op calls! Currently opSync is called with parameters of every type and count. This most definitely makes the call megamorphic. Additionally, it seems that spread params leads to V8 not being able to optimise the calls quite as well (apparently Fast Calls cannot be used with spread params).
Monomorphising op calls should lead to some improved performance. Now that unwrapping of sync ops results is done on Rust side, this is pretty simple:
```
opSync("op_foo", param1, param2);
// -> turns to
ops.op_foo(param1, param2);
```
This means sync op calls are now just directly calling the native binding function. When V8 Fast API Calls are enabled, this will enable those to be called on the optimised path.
Monomorphising async ops likely requires using callbacks and is left as an exercise to the reader.
`handleWasmStreaming` is the function that provides the binding with
the `fetch` API needed for `WebAssembly.instantiateStreaming()` and
`WebAssembly.compileStreaming()`. When I implemented it in #11200, I
thought V8 was calling these functions with the argument of the
`WebAssembly` streaming functions, without doing any resolving, and so
`handleWasmStreaming` awaits for the parameter to resolve. However,
as discovered in
https://github.com/denoland/deno/issues/13917#issuecomment-1065805565,
V8 does in fact resolve the parameter if it's a promise (and handles
rejections arising from that).
This change removes the `async` IIFE inside `handleWasmStreaming`,
letting initial errors be handled synchronously (which will however
not throw synchronously from the `WebAssembly` namespace functions).
Awaiting is still necessary for reading the bytes of the response,
though, and so there is an `async` IIFE for that.
When an exception is thrown during the processing of streaming WebAssembly,
`op_wasm_streaming_abort` is called. This op calls into V8, which synchronously
rejects the promise and calls into the promise rejection handler, if applicable.
But calling an op borrows the isolate's `JsRuntimeState` for the duration of the
op, which means it is borrowed when V8 calls into `promise_reject_callback`,
which tries to borrow it again, panicking.
This change changes `op_wasm_streaming_abort` from an op to a binding
(`Deno.core.abortWasmStreaming`). Although that binding must borrow the
`JsRuntimeState` in order to access the `WasmStreamingResource` stored in the
`OpTable`, it also takes ownership of that `WasmStreamingResource` instance,
which means it can drop any borrows of the `JsRuntimeState` before calling into
V8.
