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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/96167] fails to detect ROL pattern in simple
 case, but succeeds when operand goes through memcpy
Date: Fri, 04 Aug 2023 22:26:22 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96167

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |12.1.0
      Known to fail|                            |10.5.0

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
For x86_64, this was fixed in GCC 11+ at -O3 and for GCC 12+ for -O2 by the
vectorizer.

But I think we could do better at the code generation at the gimple level.
We have:
  vect__4.7_8 =3D MEM <vector(2) int> [(int &)x_1(D)];
  vect_tmp_3.8_9 =3D VEC_PERM_EXPR <vect__4.7_8, vect__4.7_8, { 1, 0 }>;
  MEM <vector(2) int> [(int &)x_1(D)] =3D vect_tmp_3.8_9;

Which could just be:
tmp =3D MEM<long>[(int&)x_1(D)];
tmp =3D tmp ror 32;
MEM<long>[(int&)x_1(D)] =3D tmp;=