Missing emcc --help documentation on emcc flags that affect wasm codegen?

I was looking for the flag to enable bulk memory operations in emcc, but took a bit of work to find it.

There is also the `-mnontrapping-fptoint` flag that one can pass to `emcc`, that does not seem to be documented in `emcc --help`.

Finally stumbled to https://clang.llvm.org/docs/ClangCommandLineReference.html#webassembly that lists all(?) the flags, but does not explain them.

Would it make sense to collect all these specific flags under `emcc --help`, or some other page, along with an explainer, which browser and shell versions adopted support for them and when, and e.g. a link to the spec?