Delphi 10.4.1 sees the XMM0-XMM7 register but complains about XMM8 and more, why?

Question

Delphi

asm
//  .NOFRAME

  movdqu XMM7, dqword ptr [CV]
  movdqu XMM8, dqword ptr [CV + 16]
  movdqu XMM9, dqword ptr [CV + 32]

  pxor XMM2, XMM2

  //bStep -> rdx
  cvtsd2ss XMM13, qword ptr [bStep]
  cvtsd2ss XMM0, qword ptr [bStep + 8]
  cvtsd2ss XMM1, qword ptr [bStep + 16]

Answer 1

Everything after XMM7 is for x64. Wiki.
Switch the application to the assembly under x64, or better wrap the desired piece of code in acc. condition:

{$IFDEF CPUX86}
  asm
    // ...
  end;
  {$ENDIF CPUX86}
  {$IFDEF CPUX64}
  asm
    // ...
  end;
{$ENDIF CPUX64}