[Issue 22656] New: SSE2 instructions have inconsistent layouts in the disassembler output

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22656

          Issue ID: 22656
           Summary: SSE2 instructions have inconsistent layouts in the
                    disassembler output
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Keywords: backend
          Severity: minor
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: maxhaton at gmail.com

I have listed this as SSE2 instructions however there may be more affected (it
could be the prefix in general rather than these particular instructions).

```
extern(C)
void blah()
{
    asm {
        naked;
        xor EAX, EAX;
        jmp [RIP];
        cvttpd2dq XMM0, XMM1;
        movq [RAX], XMM0;
    }
}
```
Yields
```
blah:
0000:   31 C0                   xor     EAX,EAX
0002:   48 FF 25 00 00 00 00    jmp     qword ptr [00h][RIP]
0009:66         0F E6 C1                cvttpd2dq       XMM0,XMM1
000d:66         0F D6 00                movq    [RAX],XMM0
```

The latter two instructions are not displayed properly.

>From llvm's objdump we get:
```
0000000000000000 blah:
       0: 31 c0                         xor     eax, eax
       2: 48 ff 25 00 00 00 00          jmp     qword ptr [rip]
       9: 66 0f e6 c1                   cvttpd2dq       xmm0, xmm1
       d: 66 0f d6 00                   movq    qword ptr [rax], xmm0
      11: 00 00                         add     byte ptr [rax], al
      13: 00                            <unknown>
```

>From GNU:
```
0000000000000000 <blah>:
   0:   31 c0                   xor    eax,eax
   2:   48 ff 25 00 00 00 00    rex.W jmp QWORD PTR [rip+0x0]        # 9
<blah+0x9>
   9:   66 0f e6 c1             cvttpd2dq xmm0,xmm1
   d:   66 0f d6 00             movq   QWORD PTR [rax],xmm0
  11:   00 00                   add    BYTE PTR [rax],al
```

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