On Tue, Oct 20, 2015 at 9:10 PM, Jason Merrill <ja...@redhat.com> wrote:
> I made this change on the delayed folding branch and then noticed that it
> broke pointer-arith-10.c, which you added to the testsuite. The patch
> changes the -original dump from
>
> return (char *) ((sizetype) p + (sizetype) i);
>
> to
>
> return (char *) i + (sizetype) p;
>
> It's not clear to me why the former should be preferred. Any thoughts?
We probably regressed for the former and the dump-scanning just didn't
notice. We wanted to check for
return p + (sizetype) i;
at least GCC 4.4.7 produces that and 4.5.2 regressed.
Some time ago we had a folding that explicitely swapped pointer-ness
of an integer op like the testcase was supposed to test. But I remember
I removed this because it's incorrect (pointer arithmetic is more constrained
than unsigned integer arithmetic):
2009-01-16 Richard Guenther <rguent...@suse.de>
PR tree-optimization/38835
PR middle-end/36227
* fold-const.c (fold_binary): Remove PTR + INT -> (INT)(PTR p+ INT)
and INT + PTR -> (INT)(PTR p+ INT) folding.
* tree-ssa-address.c (create_mem_ref): Properly use POINTER_PLUS_EXPR.
so I think the testcase should be simply removed.
Richard.
> Jason
>
