Emscripten miscompile with -fwasm-exception, -O0, and tls access in handler

[paradust7]

Version of emscripten/emsdk:
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 6.0.4 (fe5be6a)
clang version 24.0.0git (https:/github.com/llvm/llvm-project c050c487e9edb97ef44f53cb29fe1d8bcddb8f76)
Target: wasm32-unknown-emscripten
Thread model: posix

Reproducer

// em++ -O0 -pthread -fwasm-exceptions repro.cc -o repro.js
// node repro.js

#include <cstdio>

struct Wrapped {
  int x;
  Wrapped();
};

Wrapped::Wrapped() : x(42) {}

thread_local Wrapped tlsobj;

struct MyErr { int code; };

__attribute__((noinline)) void do_throw() {
  static volatile int always = 1;
  if (always)
    throw MyErr{7};
}

void do_catch() {
  try {
    do_throw();
  } catch (MyErr &e) {
    tlsobj.x += e.code;
    std::printf("caught, tls now %d\n", tlsobj.x);
  }
}

int main() {
  do_catch();
  std::printf("survived: %d\n", tlsobj.x);
  return 0;
}

Output

$ em++ -O0 -pthread -fwasm-exceptions repro.cc -o repro.js
$ node repro.js
wasm://wasm/0008214e:1


RuntimeError: unreachable
    at wasm://wasm/0008214e:wasm-function[28]:0xd8f
    at wasm://wasm/0008214e:wasm-function[30]:0xde1
    at wasm://wasm/0008214e:wasm-function[32]:0xe63
    at /home/ltuser/ehproblem/repro.js:876:12
    at callMain (/home/ltuser/ehproblem/repro.js:2711:15)
    at run (/home/ltuser/ehproblem/repro.js:2764:22)
    at /home/ltuser/ehproblem/repro.js:2806:25

Node.js v24.18.0