[Bug target/113180] New: MIPS: bitops on an long long struct uses ins instead dins

["syq at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113180

            Bug ID: 113180
           Summary: MIPS: bitops on an long long struct uses ins instead
                    dins
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: syq at gcc dot gnu.org
  Target Milestone: ---

```
struct yy {
        int x:32;
        int a:12;
        int b:12;
        int c:4;
        int d:4;
};

struct yy xx (struct yy a, long long b) {
        a.d = b;
        return a;
}
```

One DINS is enough for this ops, while currently the result is:

```
        dsra    $2,$4,32
        daddiu  $sp,$sp,-32
        ins     $2,$5,28,4
        sd      $4,16($sp)
        sw      $2,20($sp)
        ld      $3,16($sp)
        move    $2,$0
        sll     $4,$3,0
        dext    $4,$4,0,32
        dins    $2,$4,0,32
        dsrl    $3,$3,32
        dins    $2,$3,32,32
        jr      $31
        daddiu  $sp,$sp,32
```