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From: "hubicka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/110379] New: Unnecessary copies after early opts
Date: Fri, 23 Jun 2023 17:07:32 +0000
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X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 13.1.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110379

            Bug ID: 110379
           Summary: Unnecessary copies after early opts
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hubicka at gcc dot gnu.org
  Target Milestone: ---

Following testcase:
class a=20
{
        public:
        int b;
};
void foo (class a *);
class b: public a
{
        int test();
};
int b::test()
{
        foo (this);
        return 0;
}

produces:
int b::test (struct b * const this)
{
  struct a * _1;

  <bb 2> [local count: 1073741824]:
  _1 =3D &this_2(D)->D.2773;
  foo (_1);
  return 0;
}

I think it is equivalent to


int b::test (struct b * const this)
{
  <bb 2> [local count: 1073741824]:
  foo (this);
  return 0;
}

Which would save statement and confuse less ipa-sra and ipa-prop.=