Question about function splitting

[Hanke Zhang <hkzhang455@gmail.com>]

Hi, I have some questions about the strategy and behavior of function
splitting in gcc, like the following code:

int glob;
void f() {
  if (glob) {
    printf("short path\n");
    return;
  }
  // do lots of expensive things
  // ...
}

I hope it can be broken down like below, so that the whole function
can perhaps be inlined, which is more efficient.

int glob;
void f() {
  if (glob) {
    printf("short path\n");
    return;
  }
  f_part();
}

void f_part() {
  // do lots of expensive things
  // ...
}


But on the contrary, gcc splits it like these, which not only does not
bring any benefits, but may increase the time consumption, because the
function call itself is a more resource-intensive thing.

int glob;
void f() {
  if (glob) {
    f_part();
    return;
  }
  // do lots of expensive things
  // ...
}

void f_part() {
  printf("short path\n"); // just do this????
}

Are there any options I can offer to gcc to change this behavior? Or
do I need to make some changes in ipa-split.cc?