You actually don't need the frame pointer to unwind the stack. DWARF frame info allows the compiler to specify tables that describe the stack layout at every pr

You actually don't need the frame pointer to unwind the stack. DWARF frame info allows the compiler to specify tables that describe the stack layout at every program point, and this can be used to perform unwinding. Another reason why exceptions aren't zero-cost in practice is that compilers need to model the exceptional control-flow, and they usualy don't do a great job in this situation and miss a lot of potential optimizations.