[Bug tree-optimization/115202] New: [14/15 Regression] Missed optimization: std::min(f ? (unsigned short)m : a, ~0)

["652023330028 at smail dot nju.edu.cn" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115202

            Bug ID: 115202
           Summary: [14/15 Regression] Missed optimization: std::min(f ?
                    (unsigned short)m : a, ~0)
           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 to be independent of
'm', but gcc -O3 seems to have missed it.

https://godbolt.org/z/a6MoofoYK

unsigned short m;
#include <algorithm>
unsigned short func(int a, int f) {
    return std::min(f ? m : a, ~0);
}

GCC-trunk -O3:
func(int, int):
        movzx   eax, WORD PTR m[rip]
        test    esi, esi
        mov     edx, -1
        cmove   eax, edi
        test    eax, eax
        cmovns  eax, edx
        ret


Expected code (gcc-13.2):
func(int, int):
        mov     eax, edi
        test    edi, edi
        jns     .L4
        test    esi, esi
        jne     .L4
        ret
.L4:
        mov     eax, 65535
        ret

If we did it correctly, it's caused by
https://github.com/gcc-mirror/gcc/commit/7b34cacc5735385e7e2855d7c0a6fad60ef4a99b

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