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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/101474] SRA sometimes produces worse code
 with inline functions (seen with -fipa-icf sometimes)
Date: Fri, 16 Jul 2021 16:42:08 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101474

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|-fipa-icf generates worse   |SRA sometimes produces
                   |code for identical function |worse code with inline
                   |                            |functions (seen with
                   |                            |-fipa-icf sometimes)
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-07-16
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This worse code generation has nothing to do with -fipa-icf really as shown=
 by:
struct t {
    char x;
    int y;
};

void fn1(struct t *p, struct t v)
{
    *p =3D v;
}

void fn3(struct t *p, struct t v)
{
 fn1(p, v);
}

------ CUT ----
What is happening is SRA decides it is best to do a full scalar replacement=
 for
the v that is inlined into fn3 (from fn1).=