Code demonstrating that branchless programming isn't always useful

branchless.c

int apply_feedback_if(int level, int feedback, int deviation) {
    if (deviation < 0) {
        return level + feedback;
    } else {
        return level - feedback;
    }
}

int apply_feedback_ternary(int level, int feedback, int deviation) {
    return deviation < 0 ? level + feedback : level - feedback;
}

int apply_feedback_unconditional(int level, int feedback, int deviation) {
    int add_subtract = -1 - 2 * (deviation >> (8 * sizeof(int) - 1));
    return level + add_subtract * feedback;
}

branchless_arm64.asm

// -Og

apply_feedback_if_Og:
        tbnz    w2, #31, .L4
        sub     w0, w0, w1
.L1:
        ret
.L4:
        add     w0, w0, w1
        b       .L1
apply_feedback_ternary_Og:
        tbnz    w2, #31, .L8
        sub     w0, w0, w1
.L5:
        ret
.L8:
        add     w0, w0, w1
        b       .L5
apply_feedback_unconditional_Og:
        asr     w2, w2, 31
        mvn     w2, w2, lsl 1
        madd    w0, w2, w1, w0
        ret


// -O1

apply_feedback_if_O1:
        add     w3, w0, w1
        sub     w0, w0, w1
        cmp     w2, 0
        csel    w0, w0, w3, ge
        ret
apply_feedback_ternary_O1:
        add     w3, w0, w1
        sub     w0, w0, w1
        cmp     w2, 0
        csel    w0, w0, w3, ge
        ret
apply_feedback_unconditional_O1:
        asr     w2, w2, 31
        mvn     w2, w2, lsl 1
        madd    w0, w2, w1, w0
        ret

branchless_x86-64.asm

# -Og

apply_feedback_if_Og:
        testl   %edx, %edx
        js      .L4
        movl    %edi, %eax
        subl    %esi, %eax
        ret
.L4:
        leal    (%rdi,%rsi), %eax
        ret
apply_feedback_ternary_Og:
        testl   %edx, %edx
        js      .L8
        movl    %edi, %eax
        subl    %esi, %eax
        ret
.L8:
        leal    (%rdi,%rsi), %eax
        ret
apply_feedback_unconditional_Og:
        sarl    $31, %edx
        leal    (%rdx,%rdx), %eax
        notl    %eax
        imull   %esi, %eax
        addl    %edi, %eax
        ret


# -O1

apply_feedback_if_O1:
        leal    (%rdi,%rsi), %eax
        subl    %esi, %edi
        testl   %edx, %edx
        cmovns  %edi, %eax
        ret
apply_feedback_ternary_O1:
        leal    (%rdi,%rsi), %eax
        subl    %esi, %edi
        testl   %edx, %edx
        cmovns  %edi, %eax
        ret
apply_feedback_unconditional_O1:
        sarl    $31, %edx
        leal    (%rdx,%rdx), %eax
        notl    %eax
        imull   %esi, %eax
        addl    %edi, %eax
        ret