setjmp: read the manual

[jim at ism780b.UUCP]

>I am afraid I don't follow Sun's logic.  All that is required is to
>unravel the call stack frames by following the back-pointers.  The
>VAX built-in support for this stuff is not used on any UNIXes I am
>familiar with.  When someone does a longjmp the odds are very good
>that it is not in the inside of a tight loop, so the extra time
>taken to unwind the stack frame to fix up clobbered registers should
>not be an efficiency issue, unless your call frames have a variable
>amount of information and no internal clue about how much.

The VAX built-in stuff used is the indication on the stack of which register
variables were saved.

-- Jim Balter, INTERACTIVE Systems (ima!jim)