🚀 go-pugleaf

mjhostet@slayer.mit.edu (Mat Hostetter) writes:
>In article <1992Feb21.023817.17703@athena.mit.edu> mjhostet@slayer.mit.edu (Mat  
>Hostetter) writes:
>> I saw in the GNU status report that "C has been extended to support
>> nested functions, nonlocal gotos, and taking the address of a label."
>> Will there be any way to have an array of label-pointers and dispatch to the
>> one I want?  (eg, "goto label_array[x]".)  (I basically need a switch that  
>does  
>> no bounds checking, for a really speed-intensive loop.)
>Judging from the email I've gotten, apparently I was too concise. I *KNOW* gcc
>(sometimes) makes a dispatch table internally.  However, it makes sure that
>the index into that table (based on the switch #) references something in that
>table.  This is how it skips case's not explicitly handled by the switch and  
>higher than the highest case number.  This is perfectly reasonable behavior.
>However, in my situation can guarantee that the X in the switch (X) will
>always be handled by some case statement, so I don't want the internal bounds
>check.  Unfortunately, I've been unable to coerce gcc into avoiding the check.

A better approach would be something on the order of

#pragma nocheck
	switch(x) {
	case ...

I have used a compiler which has a command-line flag to tell it that switches
need not perform bounds checking, but a #pragma to do it with statement scope
instead of file scope would be better.  Also, it leaves your code looking more
like ANSI C instead of MUTANT C.