Undefined symbols __stack_high and __stack_low

[willcohen]

Now that nix has LLVM 15 available, I'm trying to get emscripten to 3.1.30. Nix emscripten precompiles all of libc etc in all variants for caching, which causes the build to fail due to #18057 (see log below). Do you have a sense of if I need to somehow additionally provide __stack_high and __stack_low to emcc accordingly, or does this mean that nix needs to fix its LLVM environment more generally? Per the PR, it seems like this was supposed to be a behind-the-scenes change.

cache:INFO:  - ok
cache:INFO: generating system library: sysroot/lib/wasm32-emscripten/lto/libcompiler_rt.a... (this will be cached in "/nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/libcompiler_rt.a" for subsequent builds)
system_libs:INFO: compiled 175 inputs
cache:INFO:  - ok
cache:INFO: generating system library: sysroot/lib/wasm32-emscripten/lto/libc++-noexcept.a... (this will be cached in "/nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/libc++-noexcept.a" for subsequent builds)
system_libs:INFO: compiled 48 inputs
cache:INFO:  - ok
cache:INFO: generating system library: sysroot/lib/wasm32-emscripten/lto/libc++abi-debug-noexcept.a... (this will be cached in "/nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/libc++abi-debug-noexcept.a" for subsequent builds)
system_libs:INFO: compiled 16 inputs
cache:INFO:  - ok
cache:INFO: generating system library: sysroot/lib/wasm32-emscripten/lto/libsockets.a... (this will be cached in "/nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/libsockets.a" for subsequent builds)
system_libs:INFO: compiled 21 inputs
cache:INFO:  - ok
cache:INFO: generating system asset: symbol_lists/f8cec6923d2e3e34f6340a748a3754531fdda931.txt... (this will be cached in "/nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/symbol_lists/f8cec6923d2e3e34f6340a748a3754531fdda931.txt" for subsequent builds)
cache:INFO: generating system asset: sysroot/lib/wasm32-emscripten/struct_info.json... (this will be cached in "/nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/struct_info.json" for subsequent builds)
cache:INFO:  - ok
cache:INFO:  - ok
wasm-ld: error: /nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/libcompiler_rt.a(stack_limits.o): undefined symbol: __stack_high
wasm-ld: error: /nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/libcompiler_rt.a(stack_limits.o): undefined symbol: __stack_low
emcc: error: '/nix/store/9r7fl3yf66ygmc072laxnbjdv20jrmss-emscripten-llvm-3.1.30/bin/wasm-ld -o a.out.wasm /private/tmp/nix-build-emscripten-3.1.30.drv-0/emscripten_temp_hlqdi0xn/test_0.o -L/nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto /nix/store/xrwl9qs67178cwrszilavssx32dxkwbh-emscripten-3.1.30/share/emscripten/cache/sysroot/lib/wasm32-emscripten/lto/crt1.o -lGL -lal -lhtml5 -lstandalonewasm -lstubs-debug -lc-debug -ldlmalloc -lcompiler_rt -lc++-noexcept -lc++abi-debug-noexcept -lsockets -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --allow-undefined-file=/private/tmp/nix-build-emscripten-3.1.30.drv-0/tmpl6h6wlk7.undefined --strip-debug --export-if-defined=__start_em_asm --export-if-defined=__stop_em_asm --export-if-defined=__start_em_lib_deps --export-if-defined=__stop_em_lib_deps --export-if-defined=__start_em_js --export-if-defined=__stop_em_js --export=emscripten_stack_get_end --export=emscripten_stack_get_free --export=emscripten_stack_get_base --export=emscripten_stack_get_current --export=emscripten_stack_init --export=stackSave --export=stackRestore --export=stackAlloc --export=__errno_location --export-table -z stack-size=65536 --initial-memory=16777216 --max-memory=16777216 --stack-first' failed (returned 1)

[sbc100]

The version of emscripten you are using does require a version of llvm that includes that patch: (https://reviews.llvm.org/D135910). I assume that patch is not part of LLVM 15?

More generally, emscripten is not designed to be used with a the stable releases of llvm, but instead with llvm tip-of-tree. We do all our testing against tip-of-tree, we release our emsdk binaries build from tip-of-tree, and we often depend on tip-of-tree features like this.

If you are interesting in getting things working with stable llvm releases you might want to follow this issue: #11362

[sbc100]

BTW, llvm 16 is the current stable release I think.

[willcohen]

Right, of course. Sorry for the confusion. I saw the bump to LLVM 17 on 3.1.31's release notes and assumed that 3.1.30 could still work with 15, but I didn't actually check that the LLVM commit mentioned in the PR required 16 as well. Many thanks!