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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/101750] [12 regression]
 g++.dg/vect/pr99149.cc fails on aarch64 since r12-2523
Date: Wed, 04 Aug 2021 07:37:29 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101750

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 4 Aug 2021, tnfchris at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101750
>=20
> --- Comment #5 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
> And yes the same semantics apply to 'i', but if I read it right the patch=
 in=20
> r12-2523 is tracking variables that are read but never written to. So 'i'
> escaped the same issue because it's written to somewhere.

I don't think we employ any of those C++ specific analyses, but I also=20
didn't try to track down what exactly happens.  The following
doesn't reproduce it:

int f;
struct X {
  int *q;
  int *r;
} n;
void foo (struct X *p)
{
  p->r[f] =3D p->q[0] + p->r[f];
}
void bar ()
{
  foo (&n);
}

Maybe 'n' becomes local because its type is local.  Indeed, that
seems to happen.  So maybe just give the class a name.=