gistfile1.txt

        # We return below with a ret $8.  We will return to a single
        # return instruction, which will return to the caller of our
        # caller.  We let the unwinder skip that single return
        # instruction, and just return to the real caller.

        # Here CFA points just past the return address on the stack,
        # e.g., on function entry it is %esp + 4.  Later we will
        # change it to %ebp + 8, as set by .cfi_def_cfa_register and
        # .cfi_def_cfa_offset above.  The stack looks like this:
        #       CFA + 12:       stack pointer after two returns
        #       CFA + 8:        return address of morestack caller's caller
        #       CFA + 4:        size of parameters
        #       CFA:            new stack frame size
        #       CFA - 4:        return address of this function
        #       CFA - 8:        previous value of %ebp; %ebp points here                                                                                       
        # We want to set %esp to the stack pointer after the double
        # return, which is CFA + 12.
        .cfi_offset 8, 8                # New PC stored at CFA + 8
        .cfi_escape 0x15, 4, 0x7d       # DW_CFA_val_offset_sf, %esp, 12/-4
                                        # i.e., next %esp is CFA + 12

        # Set up a normal backtrace.
        pushl   %ebp
        .cfi_def_cfa_offset 8
        .cfi_offset %ebp, -8
        movl    %esp,%ebp
        .cfi_def_cfa_register %ebp