🚀 go-pugleaf

In article <651@mcgill-vision.UUCP> mouse@mcgill-vision.UUCP writes:

>>> The method used has a large effect on whether setjmp/longjmp can put
>>> the correct values back into register variables (SYSVID says they
>>> may be unpredictable :-(.
>> Sad, but true.
>
>WHAT?!?!  I can't see any reason that longjmp can't get the registers
>back - if it can't restore them easily on that architecture then just
>have setjmp save them in the jmp_buf!  What's the problem?  This will
>make longjmp basically useless, especially in the face of compilers
>that optimize non-"register" variables into registers!

jmp_buf env;

main(){
	register int i;
	int j;
	i = j = 1;
	if(setjmp(env)){
		printf( "i==%d, j==%d\n", i, j );
		exit(0);
	}
	i = j = 2;
	func();
}

func(){
	longjmp( env, 1 );
}

The above program should ideally report that i=2. Certainly it will say
that j is 2. If i is saved in the jmp_buf, and restored by longjmp,
then i will be reported as 1.
-- 
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Greg Smith     University of Toronto      UUCP: ..utzoo!utcsri!greg
Have vAX, will hack...