Sun 4.1 cc's -O is broken on Sun 3's for levels greater than 1

[Arthur David Olson]

Here's an excerpt from a bug report that's gone off to Sun.

Description:

  The SunOS 4.1 C compiler's optimizer is broken on Sun 3's for optimization
  levels above 1.

Repeat-By:

  Note the different output below when compiling with different flags.

	Script started on Sat May 26 18:48:20 1990
	elsie$ uname -a
	SunOS elsie 4.1 1 sun3
	elsie$ cat try.c
	#include "stdio.h"

	cgf2(x)
	{
		int	dir, step, steps;

		(void) printf("%d\n", x);
		steps = (x == 50) ? 2 : 0;
		dir = -1;
		for (step = steps; step > 0; --step)
			cgf2(x + dir * step);
	}

	main()
	{
		cgf2(50);
	}
	elsie$ cc try.c
	elsie$ a.out
	50
	48
	49
	elsie$ cc -g try.c
	elsie$ a.out
	50
	48
	49
	elsie$ cc -O1 try.c
	elsie$ a.out
	50
	48
	49
	elsie$ cc -O2 try.c
	elsie$ a.out
	50
	48
	elsie$ cc -O try.c
	elsie$ a.out
	50
	48
	elsie$ exit

	script done on Sat May 26 18:49:05 1990

Workaround:
	Don't use optimization levels greater than one.

Arthur David Olson   ado at alw.nih.gov   ADO is a trademark of Ampex.