On Mon, 7 Oct 2019, Aldy Hernandez wrote:
On 10/4/19 2:09 PM, Jeff Law wrote:
You're right. Easier to refer to the before/after directly. Sometimes
diffs just suck.
OK
jeff
In testing this patch in isolation from the non-zero canonicalization patch,
I found one regression due to the fact that:
a) As discussed, two non-zero representations currently exist for unsigned
ranges.
b) ipa-prop.c has it's own hacked up value_range structure (ipa_vr) which
doesn't use any API. Since there is no agreed upon non-zero, range-ops can
sometimes (correctly) create an unsigned [1,MAX], and ipa-prop.c is
open-coding the check for a pointer non-zero to ~[0,0]. This seems like a
latent bug.
I really have no idea, nor do I care (*), what we do with ipa-prop's lack of
API. For now, I have implemented ipa_vr::nonzero_p(), and used it. When we
agree on the non-zero normalization we can adjust this method if necessary.
+bool
+ipa_vr::nonzero_p (tree expr_type) const
+{
+ if (type == VR_ANTI_RANGE && wi::eq_p (min, 0) && wi::eq_p (max, 0))
+ return true;
+
+ unsigned prec = TYPE_PRECISION (expr_type);
+ return (type == VR_RANGE
+ && wi::eq_p (min, wi::one (prec))
+ && wi::eq_p (max, wi::max_value (prec, TYPE_SIGN (expr_type))));
+}
...
else if (POINTER_TYPE_P (TREE_TYPE (ddef))
- && vr[i].type == VR_ANTI_RANGE
- && wi::eq_p (vr[i].min, 0)
- && wi::eq_p (vr[i].max, 0))
+ && vr[i].nonzero_p (TREE_TYPE (ddef)))
Attached is the final adjusted patch I have committed to trunk.
I wonder why we would ever want to ask "is this interval the one that
misses exactly the value 0" instead of "does this interval contain the
value 0". I naively believe there shouldn't even be any API for the first
question. Or if pointers really only have 2 possible intervals (besides
varying and undefined), aka [0,0] and ~[0,0], using intervals seems like
overkill for them...
--
Marc Glisse
