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From: "652023330028 at smail dot nju.edu.cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/115011] New: [14/15 Regression] Missed
 optimization: (bool) (f ? 1: t) ==> 1 when bool t = (0 >= f) + x;
Date: Thu, 09 May 2024 12:59:09 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115011

            Bug ID: 115011
           Summary: [14/15 Regression] Missed optimization: (bool) (f ? 1:
                    t) =3D=3D> 1 when bool t =3D (0 >=3D f) + x;
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: 652023330028 at smail dot nju.edu.cn
  Target Milestone: ---

Hello, we noticed that the code below can be optimized as stated in the tit=
le,
but gcc -O3 seems to have missed it.


Reduced code:
https://godbolt.org/z/xE6GEEn7j

bool x;
bool fn3(unsigned long long int f) {
    bool t =3D (0 >=3D f) + x;
    return f ? 1: t;
}

GCC -O3:
fn3(unsigned long long):
        movzx   eax, BYTE PTR x[rip]
        cmp     rdi, 1
        adc     eax, 0
        test    eax, eax
        setne   al
        test    rdi, rdi
        setne   dl
        or      eax, edx
        ret

Expected code (GCC-13.2):
fn3(unsigned long long):
        mov     eax, 1
        ret

Thank you very much for your time and effort! We look forward to hearing fr=
om
you.=