Comment by Someone
20 hours ago
But the compiler assumes the function will make forward progress. If the function does that, it will return, so why doesn’t the compiler emit a function epilogue?
20 hours ago
But the compiler assumes the function will make forward progress. If the function does that, it will return, so why doesn’t the compiler emit a function epilogue?
Because there is an infinite loop that makes the epilogue unreachable, so it is safe for the compiler to remove it!
Sure, that optimization interacts badly with the optimization that removes the infinite loop. But half the point of UB is to avoid needing to deal with such interactions, because they are defined out of existence.
The compiler can assume that the function will return, but it can also statically deduce that the function cannot return. That's a contradiction, so the compiler deduces that the function is simply UB when called, i.e. no need to emit an epilogue. It's the logical principle of explosion in compiler format, basically.