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From: "blubban at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/115423] New: Inlined strcmp optimizes poorly
Date: Tue, 11 Jun 2024 00:08:26 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115423

            Bug ID: 115423
           Summary: Inlined strcmp optimizes poorly
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: blubban at gmail dot com
  Target Milestone: ---

bool g(const char* c) {
    return __builtin_strcmp(c, ".") =3D=3D 0 ||
           __builtin_strcmp(c, "..") =3D=3D 0;
}
bool h(const char* c) {
    return (c[0] =3D=3D '.' && c[1] =3D=3D '\0') ||
           (c[0] =3D=3D '.' && c[1] =3D=3D '.' && c[2] =3D=3D '\0');
}


Compile with -O2.


Expected result: Same output from both.

Actual: The former results in a mess that, among other inefficiencies, loads
c[0] twice.


Online reproducer: https://godbolt.org/z/E4vEshvcM


(I don't know if this is an RTL or tree optimizer issue, I just guessed. Fe=
el
free to move it if it's wrong.)=