RuntimeError when encoding to UASTC with WASM

[javagl]

Description

• Windows Version 10.0
• Clone the current state (this commit at the time of writing this)
• Clone the current emsdk (this commit at the time of writing this)
• Use LLVM version 12.0.0 (if that matters)
• Run the emsdk_env.bat to set up the PATH
• Compile the encoder, as described in the webgl/encoder/README.md
  The result will be the basis_encoder.js and wasm files, attached here for reference:
  basis_encoder-build.zip
• Serve the /webgl directory with a local server
• Visit http://localhost:..../encode_test/
• Select the UASTC check box
• Hit 'Encode!'

The console shows

basis_encoder.wasm:0x36da2 Uncaught RuntimeError: memory access out of bounds
    at basis_encoder.wasm:0x36da2
    at basis_encoder.wasm:0x282a3
    at basis_encoder.wasm:0x14223
    at basis_encoder.wasm:0xb0c
    at basis_encoder.wasm:0xd7983
    at basis_encoder.wasm:0xd72a5
    at ClassHandle.BasisFile$getFileDesc [as getFileDesc] (eval at newFunc (basis_encoder.js:8:81985), <anonymous>:8:10)
    at dumpBasisFileDesc ((index):160:33)
    at dataLoaded ((index):230:3)
    at PNGDataLoaded ((index):471:3)

This happens on Chrome 116.0 and FireFox 117.0, and the same error appears when using the build output in Node.js, so it seems to be a general issue.

Possible solution

After a bunch of trial and error, I stumbled over emscripten-core/emscripten#19268 (comment) , and after changing the LINK_FLAGS in the CMakeLists.txt to include the STACK_SIZE like this...

LINK_FLAGS "--bind -s ALLOW_MEMORY_GROWTH=1 -O3 -s ASSERTIONS=0 -s INITIAL_MEMORY=299958272 -s MALLOC=emmalloc -s MODULARIZE=1 -s EXPORT_NAME=BASIS -s STACK_SIZE=10MB")

... the problem no longer appears.

If others confirm that this makes sense (or add details, like which other size than 10MB might be more appropriate), I can create a corresponding PR.

[richgel999]

Hmm - that's a lot of stack, and this didn't happen before in my testing. I will investigate this. Thanks for the filing the issue.