Re: [Intel-gfx] [PATCH 1/3] treewide: Lift switch variables out of switches

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Jan 23, 2019 at 04:17:30PM +0200, Jani Nikula wrote:
> Can't have:
> 
> 	switch (i) {
> 		int j;
> 	case 0:
>         	/* ... */
> 	}
> 
> because it can't be turned into:
> 
> 	switch (i) {
> 		int j = 0; /* not valid C */
> 	case 0:
>         	/* ... */
> 	}
> 
> but can have e.g.:
> 
> 	switch (i) {
> 	case 0:
> 		{
> 			int j = 0;
> 	        	/* ... */
> 		}
> 	}
> 
> I think Kees' approach of moving such variable declarations to the
> enclosing block scope is better than adding another nesting block.

Another nesting level would be bad, but I think this is OK:

	switch (i) {
	case 0: {
		int j = 0;
        	/* ... */
	}
	case 1: {
		void *p = q;
		/* ... */
	}
	}

I can imagine Kees' patch might have a bad effect on stack consumption,
unless GCC can be relied on to be smart enough to notice the
non-overlapping liveness of the vriables and use the same stack slots
for both.



[Index of Archives]     [Linux&nblp;USB Development]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite Secrets]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux