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Add some comments regarding __c_longjmp. NFC #21442

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Merged
sbc100 merged 2 commits into from
Feb 27, 2024
Merged

Add some comments regarding __c_longjmp. NFC #21442

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Add some comments regarding __c_longjmp. NFC
sbc100 Feb 27, 2024
422d7d4
Update system/lib/compiler-rt/emscripten_setjmp.c
sbc100 Feb 27, 2024
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6 changes: 5 additions & 1 deletion system/lib/compiler-rt/emscripten_setjmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -81,13 +81,17 @@ struct __WasmLongjmpArgs {

thread_local struct __WasmLongjmpArgs __wasm_longjmp_args;

// llvm uses `1` for the __c_longjmp tag.
// See https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/CodeGen/WasmEHFuncInfo.h
#define C_LONGJMP 1

// Wasm EH allows us to throw and catch multiple values, but that requires
// multivalue support in the toolchain, whch is not reliable at the time.
// TODO Consider switching to throwing two values at the same time later.
void __wasm_longjmp(void *env, int val) {
__wasm_longjmp_args.env = env;
__wasm_longjmp_args.val = val;
__builtin_wasm_throw(1, &__wasm_longjmp_args);
__builtin_wasm_throw(C_LONGJMP, &__wasm_longjmp_args);
}

#endif