Does Arduino support tail call elimination?

Question

I was wondering if the standard Arduino environment support tail call elimination... Does anyone know something about it?

That's like asking "does a PC support tail call elimination?" - You're asking about the wrong component. You should be asking about a specific compiler. — Damien_The_Unbeliever, Nov 09 '12 at 18:54
@Damien_The_Unbeliever: he is asking about the *standard Arduino environment* which probably implicitly refers to a precise compiler. — Basile Starynkevitch, Nov 09 '12 at 19:12

Dmitry Grigoryev · Answer 1 · 2020-10-04T12:15:54.580

Tail call elimination is indeed supported and enabled by default in Arduino IDE. This is quite standard for micro-controller world where debug aids like proper stack frames are sacrificed for memory efficiency.

Here's a test:

const int RAM_SIZE_IN_BYTES = 2048;

void f(int i) {
  Serial.println(i);
  if(i == 0) return;
  else f(i-1);
}

void setup() {
  Serial.begin(9600);
  f(RAM_SIZE_IN_BYTES);
}

void loop() {
}

This code prints numbers from 2048 to 0 to the console using a recursive function, which (without tail call optimization) requires more nested calls than available RAM bytes.

score 0 · Answer 2 · answered Nov 09 '12 at 18:41

Most C compilers don't support tail call elimination. (that notion is not in the C standard).

Some recent C compilers may support it (only when optimizing strongly), in very limited cases. In particular, GCC (a recent version like 4.6 or 4.7).

You could try a simple C function and compile it and look at the generated assembly.

Does Arduino support tail call elimination?

2 Answers2