How are case statements laid out?

Richard Henderson rth@redhat.com
Tue Dec 4 10:00:00 GMT 2001


On Tue, Dec 04, 2001 at 10:11:22AM -0500, Peter Barada wrote:
> Do you have an example?

Well, the easiest example is 

	gcc -O2 -S -fno-reorder-blocks z.c

	int foo(int i)
	{
	  if (i < 0)
	    {
	    label:
	      return -1;
	    }

	  switch (i)
	    {
	    case 0:
	      return 0;
	    case 1:
	      return 1;
	    case 2:
	      return 2;
	    case 3:
	      return 3;
	    case 4:
	      return 4;
	    case 5:
	      goto label;
	    }
	  return 6;
	}

as the goto will be folded into the table jump directly.

But apart from that -freorder-blocks will rearrange everything
as it sees fit.


r~



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