Wasm EH: "Delegate destination should be in scope" error

[kripken]

Pulled from #13485 (comment) so we don't forget, this is a fuzzer testcase that hits a clang assertion on Delegate destination should be in scope,

clang++: /b/s/w/ir/cache/builder/emscripten-releases/llvm-project/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp:1553: unsigned int (anonymous namespace)::WebAssemblyCFGStackify::getDelegateDepth(const SmallVectorImpl<(anonymous namespace)::WebAssemblyCFGStackify::EndMarkerInfo> &, const llvm::MachineBasicBlock *): Assertion `Depth < Stack.size() && "Delegate destination should be in scope"' failed.

#include <stdio.h> // avoid iostream C++ code, just test libc++abi, not libc++
#include <stdint.h>

extern void refuel();
extern void checkRecursion();
extern bool getBoolean();

void func_0() {
  try {
    if (getBoolean()) {
      throw 0;
    } else {
      try {
        try {
          if (getBoolean()) {
          }
        } catch(...) {
        }
      } catch(...) {
      }
    }
  } catch(...) {
  }
}

int main() {
  // func_0
  puts("calling func_0");
  refuel();
  try {
    func_0();
  } catch(...) {
    puts("main caught from func_0");
  }
  return 0;
}

STR: emcc -c a.cpp -fwasm-exceptions

[kripken]

I managed to generate a significantly smaller testcase:

struct Class {
  Class();
  ~Class();
};

int main() {
  Class instance1, instance2;
  try {
    throw 0;
  } catch(int) {
  }
}

cc @aheejin

(edit: same STR as above)

[kripken]

The original testcase is fixed, but I can see this assertion on latest tot (0fcee855ada6358c4fe6e8c2a7f291c54cde4876) with other ones. Here is a reduced one:

#include <stdio.h> // avoid iostream C++ code, just test libc++abi, not libc++
#include <stdint.h>

extern bool getBoolean();

struct Class {
  Class();
  ~Class();
};

int main() {
  Class instance1;
  try {
    puts("log(2)");
  } catch (int32_t) {
    try {
      throw 0;
    } catch (int32_t) {
    }
    if (getBoolean()) {
      try {
        throw 0;
      } catch (int32_t) {
      }
    }
  }
}

(STR: ./em++ a.cpp -c -fwasm-exceptions on #13485