LLVM optimization of repeated calls to const function not working when present inside basic blocks only

Question

I learned about __attribute__((const)) that allows LLVM to emit only single call when same function called with identical arguments. But I noticed that it appears to work at the scope of the basic block rather than a function.

I.e. if calls are looking something like this:

int main()
{
  var i = func(1);
  do_something_with(i);

  var y = func(1);
  do_something_with(y);
}

LLVM will make only single call to func(1).

But if instead it will look something like this:

int main(int z, int w)
{
  if (z == 1)
  {
    var i = func(1);
    do_something_with(i);
  }

  if (w == 1)
  {
    var y = func(1);
    do_something_with(y);
  }
}

LLVM will emit two separate calls to func(1) in -Oz optimization mode.

Interestingly, if I add another call to func(1) right before if block, it will fallback to making a single call.

My goal is to get LLVM to generate code in the case #2 above with a single call to func(1). I.e. I want LLVM to move func(1) to the level above if blocks.

Here is interactive example of what I am talking about - https://godbolt.org/z/8Yovo8o6a - notice how two calls to fetch cnt() is made, while only one to fetch cnt2().

Is there some kind of instructions re-ordering optimization available that can accomplish that without inserting dummy call to the "top level scope" of the function?