[Bug rtl-optimization/109527] New: redundant register assignment

[vanyacpp at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109527

            Bug ID: 109527
           Summary: redundant register assignment
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vanyacpp at gmail dot com
  Target Milestone: ---

On this function

short test(short* a)
{
    *a = 1;
    return *a;
}


latest gcc -O2 generates:

test(short*):
        mov     eax, 1
        mov     WORD PTR [rdi], ax
        mov     eax, 1
        ret

I believe the second assignment to eax is redundant and can be removed:

test(short*):
        mov     eax, 1
        mov     WORD PTR [rdi], ax
        ret