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From: "gabravier at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/95235] New: Failure to properly optimize out register
 use in bit-twiddling code
Date: Wed, 20 May 2020 09:32:58 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 11.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95235

            Bug ID: 95235
           Summary: Failure to properly optimize out register use in
                    bit-twiddling code
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

int f(int a, int b)
{
    return ((a & 1) !=3D 0) !=3D (b !=3D 0);
}

With -O3, GCC outputs this :

f(int, int):
  test esi, esi
  setne al
  xor edi, eax
  mov eax, edi
  and eax, 1
  ret

GCC should be able of outputting this instead :

f(int, int):
  test esi, esi
  setne al
  xor eax, edi
  and eax, 1
  ret

But it does not do so.=