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From: "rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/95084] [11/12 Regression] code sinking
 prevents if-conversion
Date: Mon, 31 Jan 2022 15:24:36 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95084

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|code sinking prevents       |[11/12 Regression] code
                   |if-conversion               |sinking prevents
                   |                            |if-conversion
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2022-01-31
             Status|UNCONFIRMED                 |NEW
                 CC|                            |rsandifo at gcc dot gnu.org

--- Comment #1 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.or=
g> ---
Yeah.  I'm seeing this as a GCC 11/12 regression on:

float f(float *x, float *y) {
  float res =3D 0;
  for (int i =3D 0; i < 100; ++i) {
    float next =3D __builtin_sqrtf (y[i]);
    res +=3D x[i] < 100 ? x[i] : next;
  }
  return res;
}

which is cut down from HACCmk.  Previously we could vectorise
the loop for Advanced SIMD at -Ofast, whereas now we require
-Ofast -fno-tree-sink.  (SVE can vectorise it both ways due
to predicated loads.)=