[Bug target/113882] New: V4SF->V4HI could be implemented using V4SF->V4SI and then truncation to V4HI

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113882

            Bug ID: 113882
           Summary: V4SF->V4HI could be implemented using V4SF->V4SI and
                    then truncation to V4HI
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64

Take:
```
void f(short *a, float *b)
{
        a[0] = b[0];
        a[1] = b[1];
        a[2] = b[2];
        a[3] = b[3];
}

void f1(float *a, short *b)
{
        a[0] = b[0];
        a[1] = b[1];
        a[2] = b[2];
        a[3] = b[3];
}
```
GCC can SLP f1 (which does V4SF->V4HI) but not f1.
LLVM can though:
```
f:
        ldr     q0, [x1]
        fcvtzs  v0.4s, v0.4s
        xtn     v0.4h, v0.4s
        str     d0, [x0]
        ret
```