This patch depends on D89846.
We have the patterns to fold 2 RLWINMs in ppc-mi-peephole, while some RLWINM will be generated after RA, for example rGc4690b007743. If the RLWINM generated after RA followed by another RLWINM, we expect to perform the optimization after RA, too.
Besides, RLWINM and ANDI_rec can also be folded.
Following is a scenario in C code
```
int tmp = vec_test_swdiv(x,y);
if (((__builtin_rotateleft32(tmp, 62)) & (1)) != 0){
...
}
```
`clang -c t.c -O3` generates the sequence:
```
xvtdivdp cr0,vs34,vs35
mfocrf r3,128
rlwinm r3,r3,4,28,31 --->generated in POST-RA
andi. r3,r3,4
```
This patch will fold it to:
```
xvtdivdp cr0,vs34,vs35
mfocrf r3,128
rlwinm. r3,r3,3,31,31
```