[Bug tree-optimization/96075] [8/9 Regression] bogus alignment for negative step grouped access

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96075

--- Comment #10 from Martin Liška <marxin at gcc dot gnu.org> ---
Likely started with r8-568-gf9f69dd651b2f103.

after:

.L7:
        movapd  y+8176(%rax), %xmm0
        movq    %rax, %rdx
        subq    $16, %rax
        negq    %rdx
        cmpq    $-8192, %rax
        unpcklpd        %xmm0, %xmm0
        movaps  %xmm0, x(%rdx)
        jne     .L7
        xorl    %edx, %edx
        .p2align 4,,10
        .p2align 3

before:

        movapd  (%rax), %xmm0
        addq    $16, %rdx
        leaq    -16(%rax), %rcx
        unpcklpd        %xmm0, %xmm0
        movaps  %xmm0, -16(%rdx)
        cmpq    $y, %rax
        jne     .L11
        xorl    %edx, %edx
        .p2align 4,,10
        .p2align 3