[Bug target/113179] New: MIPS

[syq at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113179

            Bug ID: 113179
           Summary: MIPS
           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 xx {
        int a:4;
        int b:24;
        int c:3;
        int d:1;
};

void xx (struct xx *a, long long b) {
        a->d = b;
}
```

When this code is built on -mabi=64, it generates asm like this:

```
        lw      $2,0($4)
        ins     $2,$5,31,1
        jr      $31
        sw      $2,0($4)
```

Since the argument B is `long long`, we cannot be sure that it is well
sign-extended, while INS asks for it:

```
If either GPR rs or GPR rt does not contain sign-extended 32-bit values (bits
63..31 equal), then the result of the operation is UNPREDICTABLE.
```