Will It Optimize? (2010)
On (1) recursion elimination ...<p>Tail-recursions are the exact equivalent of loops.<p>We've lost sight of what "recursion" means. There's a difference between recursive functions and recursive <i>algorithms</i>, which need by definition a stack and there are lots of such problems that can't be optimized to run in constant space. Whether that stack is the call stack, or a manually managed stack (within a loop or a tail-recursion), that doesn't matter, what matters is that the space requirements are definitely not constant.<p>It's nice that the GCC compiler can optimize that Fibonacci sample. However you're not getting a guarantee that it can optimize every function that is optimizable. I'm also pretty sure that the compiler is extremely limited in what it can do here. And that is dangerous, as running in constant space is often a matter of correctness, not one of optimization. I would rather have the compiler err on me if it sees non-tail recursive calls, rather than try to be smart sometimes.