On 20/05/15 15:03, Paul E. McKenney wrote:
On Wed, May 20, 2015 at 02:44:30PM +0100, Ramana Radhakrishnan wrote:
On 20/05/15 14:37, David Howells wrote:
Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
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;
Yeah. I presume it has to maintain the ordering, though.
The scheduler for e.g. is free to reorder if it can prove there is
no dependence (or indeed side-effects for y) between insns produced
for y and `x = z'.
So for example, if y is independent of z, the compiler can do the
following:
char *x;
x = z;
y;
But the dependency ordering is still maintained from z to x, so this
is not a problem.
Well, reads if any of x (assuming x was initialized elsewhere) would
need to happen before x got assigned to z.
I understood the original "maintain the ordering" as between the
statements `x = z' and `y'.
Or am I missing something subtle here?
No, it sounds like we are on the same page here.
regards
Ramana
Thanx, Paul
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