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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/114552] [13/14 Regression] wrong code at -O1 and
 above on x86_64-linux-gnu
Date: Mon, 01 Apr 2024 20:36:09 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords: needs-bisection, wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 13.3
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: target_milestone cf_reconfirmed_on short_desc
 component bug_status cf_gcctarget keywords everconfirmed
Message-ID: <bug-114552-4-9vJiDdH69Y@http.gcc.gnu.org/bugzilla/>
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114552

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |13.3
   Last reconfirmed|                            |2024-04-01
            Summary|wrong code at -O1 and above |[13/14 Regression] wrong
                   |on x86_64-linux-gnu         |code at -O1 and above on
                   |                            |x86_64-linux-gnu
          Component|tree-optimization           |middle-end
             Status|UNCONFIRMED                 |NEW
             Target|                            |x86_64-linux-gnu
           Keywords|                            |needs-bisection, wrong-code
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Better reduced testcase, removing the pragma and putting the packed on the
struct that is causing the issue:
```
struct a {
  short b;
  int c;
}__attribute__((packed));
struct d {
  struct a b;
  int e;
};
static const struct d k =3D {{1,0},0};
[[gnu::noinline]]
void p() { asm("":::"memory"); }
[[gnu::noinline]]
void q(struct a n) {
  p();
}
int main() {
  q(k.b);
  return 0;
}
```

The bug is in the middle-end expanding the call `q(k.b);` such that k.b is =
on
the stack but it messes up and uses the wrong size or something.=