What does “sibling calls” mean?

Question

On GCC manual,

-foptimize-sibling-calls

Optimize sibling and tail recursive calls.

I kn

Answer 1

It must be something like this:

int ispair(int n) { return n == 0 ? 1 : isodd(n-1); }
int isodd(int n) { return n == 0 ? 0 : ispair(n-1); }

In general, if the function call is the last sentence, then it can be replaced by a jump.

void x() { ......; y(); }

In this case y() can be replaced by a jump (or an inline function) instead of using a standard function call.