Consider this small C++ program:

=== begin ===


struct kk {
  kk() = default;
  int x = 1, y = 2, z = 3;
  ~kk() {}
};

namespace a {

  static thread_local kk v1;
  thread_local kk v2;

  void f(int x) {
    v1.x = v2.y = x;
  }

  int g() {
    return v1.x + v2.y;
  }


}


int main() {
  return 0;
}


=== end ===

Compiling and linking it with -pthread -O3 -g, gcc and clang, I can examine both a::v1 and a::v2 on x86_64 with these commands:

(gdb) start
(gdb) p a::v1
(gdb) p a::v2

However, on aarch64, I get

(gdb) p a::v1
$1 = <optimized out>
(gdb) p a::v2
$2 = {x = 1, y = 2, z = 3}


a::v1 is not optimized out, and the problem remains when I add a function that returns a reference to a::v1 (thus forcing the compiler to retain the structure in memory).

In a more complicated project, I get a different error for static thread-locals - the type is lost though the address is still visible to gdb.


Since both g++ and clang++ yield the same result, I assume the problem is with gdb.