On x64, Clang/LLVM doesn't generate the correct scope table for exceptions thrown in the same frame #10
Description
On x64, clang/llvm (version 13.0.1) doesn't seem to generate the correct scope table for the following example
VOID Test() {
__try {
asm { "ud2" }
} __except (EXCEPTION_EXECUTE_HANDLER) {
DbgPrint("Caught exception");
}
}
The scope table for the unwind data of Test() is empty (it should have one entry corresponding to the __try block). However the following is OK:
VOID ExceptionalFunction() {
asm { "ud2" }
}
VOID Test() {
__try {
ExceptionalFunction();
} __except (EXCEPTION_EXECUTE_HANDLER) {
DbgPrint("Caught exception");
}
}
Clang correctly generates the scope table for Test() (it has one entry which points to the __try block with the exception filter EXCEPTION_EXECUTE_HANDLER).
Clang/LLVM documentation claims that LLVM does not model asynchronous exceptions so it is currently impossible to catch an asynchronous exception generated in the same frame as the catching __try (x86 uses frame-based SEH instead of table based exception handling so it is OK). Our code is correct (after fixing a bug in the ReactOS code RtlpUnwindInternal --- the leaf function case didn't update the context record correctly) and can correct catch and unwind the second example above.