[Bug tree-optimization/88398] vectorization failure for a small loop to do byte comparison

[wilco at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88398

--- Comment #20 from Wilco <wilco at gcc dot gnu.org> ---
I see Kyrill added some examples that show LLVM knows how to unroll loops:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88760

This kind of thing is much worse than a trailing loop, both for branch
prediction and codesize:

        ands    x12, x11, 7
        beq     .L70
        cmp     x12, 1
        beq     .L55
        cmp     x12, 2
        beq     .L57
        cmp     x12, 3
        beq     .L59
        cmp     x12, 4
        beq     .L61
        cmp     x12, 5
        beq     .L63
        cmp     x12, 6
        bne     .L72