[VE][NFC] Change cast to dyn_cast

[kaz7]

Summary

We used cast where we should use dyn_cast. So, change it this time.
Old code cause problems if I implement brind instruction and compile
openmp using new compiler.

[simoll]

No need for review here. You can commit this as is.

[dblaikie]

Can you add a test case for this change?

If this change is not testable (eg: if all "Addr" that can reach this code are ConstantSDNodes) then it may be more suitable to remove the conditional and leave the cast in until code is committed that makes this live - that way we can be sure test coverage is added when the code is added.

[kaz7]

@dblaikie, Thank you for suggestion. I'll try to make it tonight.

llvm/lib/Target/VE/VEISelDAGToDAG.cpp

bool VEDAGToDAGISel::selectADDRzii(SDValue Addr, SDValue &Base, SDValue &Index,
   if (dyn_cast<FrameIndexSDNode>(Addr)) {
     return false;
   }
   if (Addr.getOpcode() == ISD::TargetExternalSymbol ||
       Addr.getOpcode() == ISD::TargetGlobalAddress ||
       Addr.getOpcode() == ISD::TargetGlobalTLSAddress)
     return false; // direct calls.
 
-  if (ConstantSDNode *CN = cast<ConstantSDNode>(Addr)) {
+  if (auto *CN = dyn_cast<ConstantSDNode>(Addr)) {
     if (isInt<32>(CN->getSExtValue())) {
       Base = CurDAG->getTargetConstant(0, SDLoc(Addr), MVT::i32);
       Index = CurDAG->getTargetConstant(0, SDLoc(Addr), MVT::i32);
       Offset =
           CurDAG->getTargetConstant(CN->getZExtValue(), SDLoc(Addr), MVT::i32);
       return true;
     }
   }