#include <stdio.h>

typedef struct {
  char *val;
  int len;
  int cap;
} str_t;

// str_t __attribute__ ((noinline)) test(str_t data) {

str_t __declspec(noinline) test(str_t data) {
  data.val++;
  data.len++;
  data.cap++;
  return data;
}

int main()
{
  str_t data = {0};

  data = test(data);

  printf("%p %d %d", data.val, data.len, data.cap );
  return 0;
}

xorps       xmm0,xmm0  
movdqa      xmmword ptr [rsp+20h],xmm0  

typedef union {
    __m128i m;
    struct {
      char *val;
      int  len;
      int cap;
    } v;
} str_t;

        mov     QWORD PTR [rsp-16], 0
        lea     rdx, [rdi+1]
        lea     eax, [rsi+1]
        sar     rsi, 32
        mov     QWORD PTR [rsp-24], rdx
        vmovdqa xmm1, XMMWORD PTR [rsp-24]
        add     esi, 1
        vpinsrd xmm0, xmm1, eax, 2
        vpinsrd xmm2, xmm0, esi, 3
        vmovaps XMMWORD PTR [rsp-24], xmm2
        mov     rax, QWORD PTR [rsp-24]
        mov     rdx, QWORD PTR [rsp-16]
        ret