Optimization for pure vs. const function

Question

The source code I use in this post, is also available here: https://gcc.godbolt.org/z/dGvxnv

Given this C source code:

int pure_f(int a, int b) __attribute__((pure));

int const_f(int a, int b) __attribute__((const));

int my_f(int a, int b) {
    int x = pure_f(a, b);
    if (a > 0) {
        return x;
    }
    return a;
}

If this is compiled with gcc with -O3, I would expect that the evaluation of pure_f(a, b) is moved into the if. But it is not done:

my_f(int, int):
        push    r12
        mov     r12d, edi
        call    pure_f(int, int)
        test    r12d, r12d
        cmovg   r12d, eax
        mov     eax, r12d
        pop     r12
        ret

On the other side, if const_f is called instead of pure_f, it is moved into the if:

my_f(int, int):
        test    edi, edi
        jg      .L4
        mov     eax, edi
        ret
.L4:
        jmp     const_f(int, int)

Why isn't this optimization applied for a pure function? From my understanding, this should also be possible and it seems to be beneficial.

-- EDIT --

GCC bug report (see comments): https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97307