Re: Compilers and RCU readers: Once more unto the breach!

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Wed, May 20, 2015 at 02:18:37PM +0100, David Howells wrote:
> Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
> 
> > > Additionally, what about the following code?
> > > 
> > >   char *x = y ? z : z;
> > > 
> > > Does that extend a dependency chain from z to x? If so, I can imagine a
> > > CPU breaking that in practice.
> > 
> > I am not seeing this.  I would expect the compiler to optimize to
> > something like this:
> > 
> > 	char *x = z;
> 
> Why?  What if y has a potential side-effect (say it makes a function call)?

I was thinking of "y" as a simple variable, but if it is something more
complex, then the compiler could do this, right?

	char *x;

	y;
	x = z;

							Thanx, Paul