dedf014901
```llvm
define <16 x i8> @scalar_to_16xi8(i8 %val) {
%ret = insertelement <16 x i8> undef, i8 %val, i32 0
ret <16 x i8> %ret
}
```
before
```asm
addi.d $sp, $sp, -16
st.b $a0, $sp, 0
vld $vr0, $sp, 0
addi.d $sp, $sp, 16
ret
```
after
```asm
vinsgr2vr.b $vr0, $a0, 0
ret
```
---------
Co-authored-by: Lu Weining <luweining@loongson.cn>