In this recipe, we will see how sibling call optimization works in LLVM. Sibling call optimization can be looked at as an optimized tail call, the only constraint being that the functions should share a similar function signature, that is, matching return types and matching function arguments.

$ cat sibcall.ll
declare i32 @bar(i32, i32)

define i32 @foo(i32 %a, i32 %b, i32 %c) {
  entry:
    %0 = tail call i32 @bar(i32 %a, i32 %b)
  ret i32 %0
}