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From: "christophe.leroy at csgroup dot eu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/94395] Powerpc suboptimal 64-bit constant generation
 near large values with few bits set
Date: Fri, 11 Feb 2022 13:50:31 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94395

Christophe Leroy <christophe.leroy at csgroup dot eu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |christophe.leroy at csgrou=
p dot eu

--- Comment #2 from Christophe Leroy <christophe.leroy at csgroup dot eu> -=
--
Problem still present with GCC 11.2

Linux kernel has a huge amount of sequences like:

  b4:   3d 20 fc ff     lis     r9,-769
  b8:   61 29 ff ff     ori     r9,r9,65535
  bc:   79 29 07 c6     rldicr  r9,r9,32,31
  c0:   65 29 ff ff     oris    r9,r9,65535
  c4:   61 29 ff ff     ori     r9,r9,65535
  c8:   7d 3d 03 a6     mtamr   r9

Could instead be:

  li      r9, -769
  rotldi  r9, r9, 48=