fatal error: error in backend: Cannot use EM_ASM* alongside setjmp/longjmp

[kungfooman]

I recently updated emscripten and suddenly my projects stops working with this error:

fatal error: error in backend: Cannot use EM_ASM* alongside setjmp/longjmp in Com_Frame. Please consider using EM_JS, or move the EM_ASM into another function.

My version is:

Those are equivalent to installing/activating the following:
         2.0.14             INSTALLED
         2.0.14-fastcomp

All recent (non-legacy) installable versions are:
         2.0.14    INSTALLED
         2.0.13

The function in question does not even contain a EM_ASM and everything worked before. Is there any fix for this?

Full error:

fatal error: error in backend: Cannot use EM_ASM* alongside setjmp/longjmp in Com_Frame. Please consider using EM_JS, or      move the EM_ASM into another function.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: C:/emsdk-2.0.14/upstream/bin\\clang++.exe -DEMSCRIPTEN -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -Xclang -iwithsysroot/include/SDL -target wasm32-unknown-emscripten -D__EMSCRIPTEN_major__=2 -D__EMSCRIPTEN_minor__=0 -D__EMSCRIPTEN_tiny__=14 -D_LIBCPP_ABI_VERSION=2 -Dunix -D__unix -D__unix__ -flegacy-pass-manager -Werror=implicit-function-declaration --sysroot=C:\\emsdk-2.0.14\\upstream\\emscripten\\cache\\sysroot -Xclang -iwithsysroot/include\\compat -I. -std=c++14 -DCLIENT=1 -DSERVER=1 -O2 -c common.cpp -o build/libwebgame/common.cpp.obj
1.      <eof> parser at end of file
2.      Code generation
3.      Running pass 'WebAssembly Lower Emscripten Exceptions' on module 'common.cpp'.
 #0 0x00007ffb45a3d759 (C:\WINDOWS\System32\KERNELBASE.dll+0x2d759)
 #1 0x00007ff6853ca0ea (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x5fa0ea)
 #2 0x00007ff68541281a (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x64281a)
 #3 0x00007ff684dd7e7e (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x7e7e)
 #4 0x00007ff6853cb42d (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x5fb42d)
 #5 0x00007ff685b94694 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0xdc4694)
 #6 0x00007ff685b90df6 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0xdc0df6)
 #7 0x00007ff684ffc02d (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x22c02d)
 #8 0x00007ff686218c35 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x1448c35)
 #9 0x00007ff68660ca4a (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x183ca4a)
#10 0x00007ff68783e303 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x2a6e303)
#11 0x00007ff686563675 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x1793675)
#12 0x00007ff68554a493 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x77a493)
#13 0x00007ff6855f32c5 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x8232c5)
#14 0x00007ff684dd7bac (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x7bac)
#15 0x00007ff684dd47c4 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x47c4)
#16 0x00007ff68631c546 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x154c546)
#17 0x00007ff6853c9f33 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x5f9f33)
#18 0x00007ff68631c1d2 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x154c1d2)
#19 0x00007ff685509a38 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x739a38)
#20 0x00007ff685509f1b (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x739f1b)
#21 0x00007ff685522246 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x752246)
#22 0x00007ff684dd4004 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x4004)
#23 0x00007ff68838f8c8 (C:\emsdk-2.0.14\upstream\bin\clang++.exe+0x35bf8c8)
#24 0x00007ffb47cd7034 (C:\WINDOWS\System32\KERNEL32.DLL+0x17034)
#25 0x00007ffb4831d0d1 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x4d0d1)
emcc: error: 'C:/emsdk-2.0.14/upstream/bin\clang++.exe -DEMSCRIPTEN -fignore-exceptions -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -Xclang -iwithsysroot/include/SDL -target wasm32-unknown-emscripten -D__EMSCRIPTEN_major__=2 -D__EMSCRIPTEN_minor__=0 -D__EMSCRIPTEN_tiny__=14 -D_LIBCPP_ABI_VERSION=2 -Dunix -D__unix -D__unix__ -flegacy-pass-manager -Werror=implicit-function-declaration --sysroot=C:\emsdk-2.0.14\upstream\emscripten\cache\sysroot -Xclang -iwithsysroot/include\compat -I. -std=c++14 -DCLIENT=1 -DSERVER=1 -O2 -c common.cpp -o build/libwebgame/common.cpp.obj' failed (1)
ERROR: CMD: emcc   -I.  -std=c++14  -DCLIENT=1   -DSERVER=1  -O2 -o build/libwebgame/common.cpp.obj -c common.cpp

[kripken]

This may change depending on optimizations, for example, if LLVM inlines a function with EM_ASM into a function with setjmp, or vice versa. Checking that function Com_Frame, maybe you can see why this happens, and adding __attribute__((noinline)) can help work around it.

[kungfooman]

Wow, thanks a lot @kripken !

I boiled it down to this code:

int Sys_Milliseconds ()
{
    int             sys_curtime = 0;    
    static qboolean initialized = qfalse;
    int ticks = 0;
#ifdef EMSCRIPTEN
    ticks = EM_ASM_INT({  
        return _SDL_GetTicks();
    }, 123);
#else
    //ticks = callback_getticks();
    //ticks = SDL_GetTicks();
#endif
    if (!initialized) {
        sys_timeBase = ticks;
        initialized = qtrue;
    }
    sys_curtime = ticks - sys_timeBase;
    //if (callback_getticks)
    //    sys_curtime = callback_getticks() * 10;
    //printf("milliseconds=%d\n", sys_curtime);
    return sys_curtime;
    //return imguidata.global_ticks;
}

CCALL void Com_Frame() {
    if ( setjmp (abortframe) ) {
        return;            // an ERR_DROP was thrown
    }
    Sys_Milliseconds();
}

When I write __attribute__((noinline)) in front of int Sys_Milliseconds () it works again 🙏

[stale]

This issue has been automatically marked as stale because there has been no activity in the past year. It will be closed automatically if no further activity occurs in the next 30 days. Feel free to re-open at any time if this issue is still relevant.