WASM: Future Prospects

[Shaikh-Ubaid]

• We are currently building lfortran to wasm in debug type.
  • As previously discussed, ideally it should be in release type (for speed). dev.lfortran.org: use Release build #1240
• Currently, the runtime library is not supported at dev.lfortran.org (WASM: Support runtime library #643, WASM: Fix import functions bug #657)
• CI: Testing NodeJS version compare fix/make-robust
  • The statement string(COMPARE GREATER_EQUAL "${WASM_EXEC_VERSION}" "v16.0.0" IS_NODE_ABOVE_16) in integration_tests/CMakeLists.txt can/might return wrong/undesired result when the node version is between (around) v2.0.0 to <= v9.x.x.
• Add Bitwise operators
• Use passes (ImpliedDoLoop and others) for arrays (Support arrays / numpy in WASM lcompilers/lpython#1483)
  • This could hopefully support operations involving arrays.
• Verify preamble in wasm decoding (WAT: verify preamble #631)
  • During wasm to wat conversion, we currently skip the first eight bytes of wasm (as they contain the magic number and wasm version). Ideally, we should check/verify these eight bytes and return/exit with an error.
• Auto-generating wasm_to_wat.h using script
• Pass wasm_bytes stream from C++ to JavaScript using Heap. That is Heap Method for accessing uint8_t* wasm_bytes.
  • To pass bytes from lfortran.wasm to the JavaScript frontend for execution, we construct a string from the bytes (since, few attempts to pass bytes directly did not succeed, where as passing strings was successful).
• The current wasm_to_wat.cpp might/can parse wasm with sections in any (random) order. WASM: give an error message if sections are in wrong order lcompilers/lpython#1486
  • As per the wasm docs, it seems that the different sections in wasm should/must appear as per the increasing order of their section ids (I guess, custom sections might be an exception). We should possibly try to generate error if the sections in the wasm are not in proper/expected order.
• Use/Provide WASI Environment for executing generated wasm (Ensure the WASM output is compatible with wasmtime + WASI lcompilers/lpython#1461)
• Support C runtime library in the LLVM based WASM Backend. WASM: Runtime Library lcompilers/lpython#1413
• WASM: RuntimeError: memory access out of bounds (WASM: RuntimeError: memory access out of bounds #658).

[Shaikh-Ubaid]

Related: #589

[certik]

Closing in favor of lcompilers/lpython#1485. All items are either fixed, or we created issues for them (in either LPython or LFortran) and are tracking it in 1485.