// This is the amount of bytes that need to be left on the stack before increasing the size. // It must be at least as large as the stack required by any code that does not call // `ensure_sufficient_stack`. const RED_ZONE: usize = 100 * 1024; // 100k // Only the first stack that is pushed, grows exponentially (2^n * STACK_PER_RECURSION) from then // on. This flag has performance relevant characteristics. Don't set it too high. const STACK_PER_RECURSION: usize = 1 * 1024 * 1024; // 1MB /// Grows the stack on demand to prevent stack overflow. Call this in strategic locations /// to "break up" recursive calls. E.g. almost any call to `visit_expr` or equivalent can benefit /// from this. /// /// Should not be sprinkled around carelessly, as it causes a little bit of overhead. #[inline] pub fn ensure_sufficient_stack(f: impl FnOnce() -> R) -> R { stacker::maybe_grow(RED_ZONE, STACK_PER_RECURSION, f) }