This patch is regression fix patch, not an optimization patch.
Since trunk GCC generates redundant vsetvl than GCC-13.
This is the case:
bb 2:
def a2 (vsetvl a2, zero)
bb 3:
use a2
bb 4:
use a2 (vle)
before this patch:
bb 2:
vsetvl a2 zero
bb 3:
vsetvl zero, zero ----> should be eliminated.
bb 4:
vle.v
The root cause is we didn't set bb 3 as transparent since the incorrect codes.
bb 3 didn't modify "a2" just use it, the VSETVL status from bb 2 can be available to bb 3 and bb 4:
bb 2 -> bb 3 -> bb4.
Another regression fix is anticipation calculation:
bb 4:
use a5 (sub)
use a5 (vle)
The vle VSETVL status should be considered as anticipated as long as both sub and vle a5 def are coming from same def.