Disable import/export name mangling in -O3 builds

[allsey87]

I am working with a custom runtime and would like to disable the name mangling in the generated runtime, i.e., the renaming of imports/exports inside the WebAssembly module to a, b, c, etc. While STANDALONE_WASM sounds ideal for this use case, unfortunately it is nowhere near ready for more complicated applications that need runtime support for Pthreads and Asyncify. Is there a hack or a workaround to disable this name mangling so that the module imports/exports have deterministic names?

Version of emscripten/emsdk:

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.0.1 (5ebe1d4)
clang version 14.0.0 (https://github.com/llvm/llvm-project d98dfb2baabb647a6ac4c4f4399999cfc44433db)
Target: wasm32-unknown-emscripten
Thread model: posix

[allsey87]

There is an option in one of the Binaryen tools wasm-emscripten-finalize.cpp on line 60 that could be relevant. Also this issue is marked as relevant in the code: WebAssembly/binaryen#3043.

[kripken]

You can build at -O2 instead of -O3 to disable that optimization.

[sbc100]

We did have another request to explicitly disable this minification from @eyebrowsoffire.. should we consider making this separately configurable?

[kripken]

I guess that would mean moving MINIFY_WASM_IMPORTS_AND_EXPORTS from an internal setting to an external one (plus some minor changes in emcc.py). I wouldn't be opposed, but it is a new public setting. Is -O2 not good enough, @eyebrowsoffire ?