[Bug tree-optimization/100173] telecom/viterb00data_1 has 16.92% regression compared O2 -ftree-vectorize -fvect-cost-model=very-cheap to O2 on CLX/ICX, 9% regression on znver3

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100173

--- Comment #7 from Drea Pinski <pinskia at gcc dot gnu.org> ---
I have a patch to add simple TARGET_MEM_REF support.
Which gives now:
```
.L4:
        movzwl  (%r9), %esi
        movzwl  -62(%rax), %edi
        addq    $2, %r9
        xorl    %r8d, %r8d
        movzwl  2(%rax), %ecx
        subl    %esi, %edi
        addl    %esi, %ecx
        cmpw    %cx, %di
        cmovge  %r10, %r8
        cmovge  %edi, %ecx
        movzwl  (%rax,%r8), %edi
        movw    %cx, 2(%rdx)
        leal    (%rdi,%rdi), %ecx
        movw    %cx, (%rdx)
        movzwl  -62(%rax), %edi
        movzwl  2(%rax), %ecx
        addl    %esi, %edi
        subl    %esi, %ecx
        xorl    %esi, %esi
        cmpw    %cx, %di
        cmovge  %r10, %rsi
        cmovge  %edi, %ecx
        addq    $8, %rdx
        addq    $4, %rax
        movzwl  -4(%rax,%rsi), %esi
        movw    %cx, -2(%rdx)
        leal    1(%rsi,%rsi), %ecx
        movw    %cx, -4(%rdx)
        cmpq    %rdx, %r11
        jne     .L4
```

That is no branches.
And it is similar to what LLVM gets at -O2.

Note a simple testcase like:
```
int f(int a, int *b, int *d, int *c)
{
    for(int i = 0; i < 1024; i++)
    {
      int t;
      int t1;
      if (b[i] > d[i]) {
        t1 = b[i];
        t = c[i];
      }
      else {
        t1 = d[i];
        t = c[i+2];
      }
      b[i] = t+t1;
    }
}
````
is supported. even if the target_mem_ref is more complex :).