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From: "christophm30 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug rtl-optimization/105314] [12 Regression] ifcvt regression in
 noce_try_store_flag_mask
Date: Mon, 25 Apr 2022 22:40:17 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105314

--- Comment #6 from Christoph M=C3=BCllner <christophm30 at gmail dot com> =
---
The proposed fix is triggering an invalid transformation.

The pattern we need to transform is:
  Convert "if (test) x =3D 0;" to "x &=3D -(test =3D=3D 0);"

If there is an else branch, we can't apply the transformation.

Error case:
"""
long func2 (long a, long b, long c)  // should not be optimized
{
    if (c)
        a =3D 0;
    else
        a =3D 5;
    return a;
}
"""

With the patch this gets compiled to:
0000000000000006 <func2>:
   6:   00163513                seqz    a0,a2
   a:   40a00533                neg     a0,a0
   e:   8915                    andi    a0,a0,5
  10:   8082                    ret=