...variables
  // code

  // cleanup/return
  mov sp, bp
  ret
[/code]

 Technically alloca simply returns the current...

...the prelude and the prologue:

int pmovmskb2(byte16 v)
{
    asm
    {
        naked;
        pmovmskb EAX, XMM0;
        ret;
    }
}

...EAX, XMM0;
                    mov RSP, RBP;
                    pop RBP;
                    ret;
                }

Looks like the SIMD param is passed...

...movdqa XMM0, dword ptr[RBP-0x10];
        pmovmskb EAX, XMM0;
        mov RSP, RBP;
        pop RBP;
        ret;
    }
}

...EAX, XMM0;
        mov RSP, RBP;
        pop RBP;
        ret;
    }
}

Note that there is maybe a DMD...

...sometimes a few other register restores */
leave;
ret;


`leave` btw is the same as `mov...

...things, but it seems to be the `ret;`.

This doesn't segfault:
----
int pmovmskb(byte16...

...asm
    {
        movdqa XMM0, v;
        pmovmskb EAX, XMM0;
        ret;
    }
}
void main()
{
    byte16 a = [-1, 0, -1...

...it is like a hack (&ret[0, 0, 0])[0 .. ret.elementsCount]).

Have you made...

...mov rsp, rbp
000000000044C957h  pop rbp
000000000044C958h  ret
;-------------------------------------

;------- SUB 000000000044C960h -------
; NAMED: tupNo
000000000044C960h  sub rsp...